Brain correlates of automatic visual change detection.

PubMed

Cléry, H; Andersson, F; Fonlupt, P; Gomot, M

2013-07-15

A number of studies support the presence of visual automatic detection of change, but little is known about the brain generators involved in such processing and about the modulation of brain activity according to the salience of the stimulus. The study presented here was designed to locate the brain activity elicited by unattended visual deviant and novel stimuli using fMRI. Seventeen adult participants were presented with a passive visual oddball sequence while performing a concurrent visual task. Variations in BOLD signal were observed in the modality-specific sensory cortex, but also in non-specific areas involved in preattentional processing of changing events. A degree-of-deviance effect was observed, since novel stimuli elicited more activity in the sensory occipital regions and at the medial frontal site than small changes. These findings could be compared to those obtained in the auditory modality and might suggest a "general" change detection process operating in several sensory modalities. Copyright © 2013 Elsevier Inc. All rights reserved.

Early auditory change detection implicitly facilitated by ignored concurrent visual change during a Braille reading task.

PubMed

Aoyama, Atsushi; Haruyama, Tomohiro; Kuriki, Shinya

2013-09-01

Unconscious monitoring of multimodal stimulus changes enables humans to effectively sense the external environment. Such automatic change detection is thought to be reflected in auditory and visual mismatch negativity (MMN) and mismatch negativity fields (MMFs). These are event-related potentials and magnetic fields, respectively, evoked by deviant stimuli within a sequence of standard stimuli, and both are typically studied during irrelevant visual tasks that cause the stimuli to be ignored. Due to the sensitivity of MMN/MMF to potential effects of explicit attention to vision, however, it is unclear whether multisensory co-occurring changes can purely facilitate early sensory change detection reciprocally across modalities. We adopted a tactile task involving the reading of Braille patterns as a neutral ignore condition, while measuring magnetoencephalographic responses to concurrent audiovisual stimuli that were infrequently deviated either in auditory, visual, or audiovisual dimensions; 1000-Hz standard tones were switched to 1050-Hz deviant tones and/or two-by-two standard check patterns displayed on both sides of visual fields were switched to deviant reversed patterns. The check patterns were set to be faint enough so that the reversals could be easily ignored even during Braille reading. While visual MMFs were virtually undetectable even for visual and audiovisual deviants, significant auditory MMFs were observed for auditory and audiovisual deviants, originating from bilateral supratemporal auditory areas. Notably, auditory MMFs were significantly enhanced for audiovisual deviants from about 100 ms post-stimulus, as compared with the summation responses for auditory and visual deviants or for each of the unisensory deviants recorded in separate sessions. Evidenced by high tactile task performance with unawareness of visual changes, we conclude that Braille reading can successfully suppress explicit attention and that simultaneous multisensory changes can implicitly strengthen automatic change detection from an early stage in a cross-sensory manner, at least in the vision to audition direction.

Decoding Reveals Plasticity in V3A as a Result of Motion Perceptual Learning

PubMed Central

Shibata, Kazuhisa; Chang, Li-Hung; Kim, Dongho; Náñez, José E.; Kamitani, Yukiyasu; Watanabe, Takeo; Sasaki, Yuka

2012-01-01

Visual perceptual learning (VPL) is defined as visual performance improvement after visual experiences. VPL is often highly specific for a visual feature presented during training. Such specificity is observed in behavioral tuning function changes with the highest improvement centered on the trained feature and was originally thought to be evidence for changes in the early visual system associated with VPL. However, results of neurophysiological studies have been highly controversial concerning whether the plasticity underlying VPL occurs within the visual cortex. The controversy may be partially due to the lack of observation of neural tuning function changes in multiple visual areas in association with VPL. Here using human subjects we systematically compared behavioral tuning function changes after global motion detection training with decoded tuning function changes for 8 visual areas using pattern classification analysis on functional magnetic resonance imaging (fMRI) signals. We found that the behavioral tuning function changes were extremely highly correlated to decoded tuning function changes only in V3A, which is known to be highly responsive to global motion with human subjects. We conclude that VPL of a global motion detection task involves plasticity in a specific visual cortical area. PMID:22952849

The Role of Attention in the Maintenance of Feature Bindings in Visual Short-term Memory

ERIC Educational Resources Information Center

Johnson, Jeffrey S.; Hollingworth, Andrew; Luck, Steven J.

2008-01-01

This study examined the role of attention in maintaining feature bindings in visual short-term memory. In a change-detection paradigm, participants attempted to detect changes in the colors and orientations of multiple objects; the changes consisted of new feature values in a feature-memory condition and changes in how existing feature values were…

Neural correlates of change detection and change blindness in a working memory task.

PubMed

Pessoa, Luiz; Ungerleider, Leslie G

2004-05-01

Detecting changes in an ever-changing environment is highly advantageous, and this ability may be critical for survival. In the present study, we investigated the neural substrates of change detection in the context of a visual working memory task. Subjects maintained a sample visual stimulus in short-term memory for 6 s, and were asked to indicate whether a subsequent, test stimulus matched or did not match the original sample. To study change detection largely uncontaminated by attentional state, we compared correct change and correct no-change trials at test. Our results revealed that correctly detecting a change was associated with activation of a network comprising parietal and frontal brain regions, as well as activation of the pulvinar, cerebellum, and inferior temporal gyrus. Moreover, incorrectly reporting a change when none occurred led to a very similar pattern of activations. Finally, few regions were differentially activated by trials in which a change occurred but subjects failed to detect it (change blindness). Thus, brain activation was correlated with a subject's report of a change, instead of correlated with the physical change per se. We propose that frontal and parietal regions, possibly assisted by the cerebellum and the pulvinar, might be involved in controlling the deployment of attention to the location of a change, thereby allowing further processing of the visual stimulus. Visual processing areas, such as the inferior temporal gyrus, may be the recipients of top-down feedback from fronto-parietal regions that control the reactive deployment of attention, and thus exhibit increased activation when a change is reported (irrespective of whether it occurred or not). Whereas reporting that a change occurred, be it correctly or incorrectly, was associated with strong activation in fronto-parietal sites, change blindness appears to involve very limited territories.

The Comparison of Visual Working Memory Representations with Perceptual Inputs

PubMed Central

Hyun, Joo-seok; Woodman, Geoffrey F.; Vogel, Edward K.; Hollingworth, Andrew

2008-01-01

The human visual system can notice differences between memories of previous visual inputs and perceptions of new visual inputs, but the comparison process that detects these differences has not been well characterized. This study tests the hypothesis that differences between the memory of a stimulus array and the perception of a new array are detected in a manner that is analogous to the detection of simple features in visual search tasks. That is, just as the presence of a task-relevant feature in visual search can be detected in parallel, triggering a rapid shift of attention to the object containing the feature, the presence of a memory-percept difference along a task-relevant dimension can be detected in parallel, triggering a rapid shift of attention to the changed object. Supporting evidence was obtained in a series of experiments that examined manual reaction times, saccadic reaction times, and event-related potential latencies. However, these experiments also demonstrated that a slow, limited-capacity process must occur before the observer can make a manual change-detection response. PMID:19653755

False predictions about the detectability of visual changes: the role of beliefs about attention, memory, and the continuity of attended objects in causing change blindness blindness.

PubMed

Levin, Daniel T; Drivdahl, Sarah B; Momen, Nausheen; Beck, Melissa R

2002-12-01

Recently, a number of experiments have emphasized the degree to which subjects fail to detect large changes in visual scenes. This finding, referred to as "change blindness," is often considered surprising because many people have the intuition that such changes should be easy to detect. documented this intuition by showing that the majority of subjects believe they would notice changes that are actually very rarely detected. Thus subjects exhibit a metacognitive error we refer to as "change blindness blindness." Here, we test whether CBB is caused by a misestimation of the perceptual experience associated with visual changes and show that it persists even when the pre- and postchange views are separated by long delays. In addition, subjects overestimate their change detection ability both when the relevant changes are illustrated by still pictures, and when they are illustrated using videos showing the changes occurring in real time. We conclude that CBB is a robust phenomenon that cannot be accounted for by failure to understand the specific perceptual experience associated with a change. Copyright 2002 Elsevier Science (USA)

Qualitative Contrast between Knowledge-Limited Mixed-State and Variable-Resources Models of Visual Change Detection

ERIC Educational Resources Information Center

Nosofsky, Robert M.; Donkin, Chris

2016-01-01

We report an experiment designed to provide a qualitative contrast between knowledge-limited versions of mixed-state and variable-resources (VR) models of visual change detection. The key data pattern is that observers often respond "same" on big-change trials, while simultaneously being able to discriminate between same and small-change…

Two visual systems in monitoring of dynamic traffic: effects of visual disruption.

PubMed

Zheng, Xianjun Sam; McConkie, George W

2010-05-01

Studies from neurophysiology and neuropsychology provide support for two separate object- and location-based visual systems, ventral and dorsal. In the driving context, a study was conducted using a change detection paradigm to explore drivers' ability to monitor the dynamic traffic flow, and the effects of visual disruption on these two visual systems. While driving, a discrete change, such as vehicle location, color, or identity, was occasionally made in one of the vehicles on the road ahead of the driver. Experiment results show that without visual disruption, all changes were detected very well; yet, these equally perceivable changes were disrupted differently by a brief blank display (150 ms): the detection of location changes was especially reduced. The disruption effects were also bigger for the parked vehicle compared to the moving ones. The findings support the different roles for two visual systems in monitoring the dynamic traffic: the "where", dorsal system, tracks vehicle spatiotemporal information on perceptual level, encoding information in a coarse and transient manner; whereas the "what", ventral system, monitors vehicles' featural information, encoding information more accurately and robustly. Both systems work together contributing to the driver's situation awareness of traffic. Benefits and limitations of using the driving simulation are also discussed. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Posterior parietal cortex mediates encoding and maintenance processes in change blindness.

PubMed

Tseng, Philip; Hsu, Tzu-Yu; Muggleton, Neil G; Tzeng, Ovid J L; Hung, Daisy L; Juan, Chi-Hung

2010-03-01

It is commonly accepted that right posterior parietal cortex (PPC) plays an important role in updating spatial representations, directing visuospatial attention, and planning actions. However, recent studies suggest that right PPC may also be involved in processes that are more closely associated with our visual awareness as its activation level positively correlates with successful conscious change detection (Beck, D.M., Rees, G., Frith, C.D., & Lavie, N. (2001). Neural correlates of change detection and change blindness. Nature Neuroscience, 4, 645-650.). Furthermore, disruption of its activity increases the occurrences of change blindness, thus suggesting a causal role for right PPC in change detection (Beck, D.M., Muggleton, N., Walsh, V., & Lavie, N. (2006). Right parietal cortex plays a critical role in change blindness. Cerebral Cortex, 16, 712-717.). In the context of a 1-shot change detection paradigm, we applied transcranial magnetic stimulation (TMS) during different time intervals to elucidate the temporally precise involvement of PPC in change detection. While subjects attempted to detect changes between two image sets separated by a brief time interval, TMS was applied either during the presentation of picture 1 when subjects were encoding and maintaining information into visual short-term memory, or picture 2 when subjects were retrieving information relating to picture 1 and comparing it to picture 2. Our results show that change blindness occurred more often when TMS was applied during the viewing of picture 1, which implies that right PPC plays a crucial role in the processes of encoding and maintaining information in visual short-term memory. In addition, since our stimuli did not involve changes in spatial locations, our findings also support previous studies suggesting that PPC may be involved in the processes of encoding non-spatial visual information (Todd, J.J. & Marois, R. (2004). Capacity limit of visual short-term memory in human posterior parietal cortex. Nature, 428, 751-754.). Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Recent Visual Experience Shapes Visual Processing in Rats through Stimulus-Specific Adaptation and Response Enhancement.

PubMed

Vinken, Kasper; Vogels, Rufin; Op de Beeck, Hans

2017-03-20

From an ecological point of view, it is generally suggested that the main goal of vision in rats and mice is navigation and (aerial) predator evasion [1-3]. The latter requires fast and accurate detection of a change in the visual environment. An outstanding question is whether there are mechanisms in the rodent visual system that would support and facilitate visual change detection. An experimental protocol frequently used to investigate change detection in humans is the oddball paradigm, in which a rare, unexpected stimulus is presented in a train of stimulus repetitions [4]. A popular "predictive coding" theory of cortical responses states that neural responses should decrease for expected sensory input and increase for unexpected input [5, 6]. Despite evidence for response suppression and enhancement in noninvasive scalp recordings in humans with this paradigm [7, 8], it has proven challenging to observe both phenomena in invasive action potential recordings in other animals [9-11]. During a visual oddball experiment, we recorded multi-unit spiking activity in rat primary visual cortex (V1) and latero-intermediate area (LI), which is a higher area of the rodent ventral visual stream. In rat V1, there was only evidence for response suppression related to stimulus-specific adaptation, and not for response enhancement. However, higher up in area LI, spiking activity showed clear surprise-based response enhancement in addition to stimulus-specific adaptation. These results show that neural responses along the rat ventral visual stream become increasingly sensitive to changes in the visual environment, suggesting a system specialized in the detection of unexpected events. Copyright © 2017 Elsevier Ltd. All rights reserved.

A new type of change blindness: smooth, isoluminant color changes are monitored on a coarse spatial scale.

PubMed

Goddard, Erin; Clifford, Colin W G

2013-04-22

Attending selectively to changes in our visual environment may help filter less important, unchanging information within a scene. Here, we demonstrate that color changes can go unnoticed even when they occur throughout an otherwise static image. The novelty of this demonstration is that it does not rely upon masking by a visual disruption or stimulus motion, nor does it require the change to be very gradual and restricted to a small section of the image. Using a two-interval, forced-choice change-detection task and an odd-one-out localization task, we showed that subjects were slowest to respond and least accurate (implying that change was hardest to detect) when the color changes were isoluminant, smoothly varying, and asynchronous with one another. This profound change blindness offers new constraints for theories of visual change detection, implying that, in the absence of transient signals, changes in color are typically monitored at a coarse spatial scale.

Object memory and change detection: dissociation as a function of visual and conceptual similarity.

PubMed

Yeh, Yei-Yu; Yang, Cheng-Ta

2008-01-01

People often fail to detect a change between two visual scenes, a phenomenon referred to as change blindness. This study investigates how a post-change object's similarity to the pre-change object influences memory of the pre-change object and affects change detection. The results of Experiment 1 showed that similarity lowered detection sensitivity but did not affect the speed of identifying the pre-change object, suggesting that similarity between the pre- and post-change objects does not degrade the pre-change representation. Identification speed for the pre-change object was faster than naming the new object regardless of detection accuracy. Similarity also decreased detection sensitivity in Experiment 2 but improved the recognition of the pre-change object under both correct detection and detection failure. The similarity effect on recognition was greatly reduced when 20% of each pre-change stimulus was masked by random dots in Experiment 3. Together the results suggest that the level of pre-change representation under detection failure is equivalent to the level under correct detection and that the pre-change representation is almost complete. Similarity lowers detection sensitivity but improves explicit access in recognition. Dissociation arises between recognition and change detection as the two judgments rely on the match-to-mismatch signal and mismatch-to-match signal, respectively.

Accessing long-term memory representations during visual change detection.

PubMed

Beck, Melissa R; van Lamsweerde, Amanda E

2011-04-01

In visual change detection tasks, providing a cue to the change location concurrent with the test image (post-cue) can improve performance, suggesting that, without a cue, not all encoded representations are automatically accessed. Our studies examined the possibility that post-cues can encourage the retrieval of representations stored in long-term memory (LTM). Participants detected changes in images composed of familiar objects. Performance was better when the cue directed attention to the post-change object. Supporting the role of LTM in the cue effect, the effect was similar regardless of whether the cue was presented during the inter-stimulus interval, concurrent with the onset of the test image, or after the onset of the test image. Furthermore, the post-cue effect and LTM performance were similarly influenced by encoding time. These findings demonstrate that monitoring the visual world for changes does not automatically engage LTM retrieval.

Visual-Spatial Attention Aids the Maintenance of Object Representations in Visual Working Memory

PubMed Central

Williams, Melonie; Pouget, Pierre; Boucher, Leanne; Woodman, Geoffrey F.

2013-01-01

Theories have proposed that the maintenance of object representations in visual working memory is aided by a spatial rehearsal mechanism. In this study, we used two different approaches to test the hypothesis that overt and covert visual-spatial attention mechanisms contribute to the maintenance of object representations in visual working memory. First, we tracked observers’ eye movements while remembering a variable number of objects during change-detection tasks. We observed that during the blank retention interval, participants spontaneously shifted gaze to the locations that the objects had occupied in the memory array. Next, we hypothesized that if attention mechanisms contribute to the maintenance of object representations, then drawing attention away from the object locations during the retention interval would impair object memory during these change-detection tasks. Supporting this prediction, we found that attending to the fixation point in anticipation of a brief probe stimulus during the retention interval reduced change-detection accuracy even on the trials in which no probe occurred. These findings support models of working memory in which visual-spatial selection mechanisms contribute to the maintenance of object representations. PMID:23371773

Proactive Interference Does Not Meaningfully Distort Visual Working Memory Capacity Estimates in the Canonical Change Detection Task

PubMed Central

Lin, Po-Han; Luck, Steven J.

2012-01-01

The change detection task has become a standard method for estimating the storage capacity of visual working memory. Most researchers assume that this task isolates the properties of an active short-term storage system that can be dissociated from long-term memory systems. However, long-term memory storage may influence performance on this task. In particular, memory traces from previous trials may create proactive interference that sometimes leads to errors, thereby reducing estimated capacity. Consequently, the capacity of visual working memory may be higher than is usually thought, and correlations between capacity and other measures of cognition may reflect individual differences in proactive interference rather than individual differences in the capacity of the short-term storage system. Indeed, previous research has shown that change detection performance can be influenced by proactive interference under some conditions. The purpose of the present study was to determine whether the canonical version of the change detection task – in which the to-be-remembered information consists of simple, briefly presented features – is influenced by proactive interference. Two experiments were conducted using methods that ordinarily produce substantial evidence of proactive interference, but no proactive interference was observed. Thus, the canonical version of the change detection task can be used to assess visual working memory capacity with no meaningful influence of proactive interference. PMID:22403556

Proactive interference does not meaningfully distort visual working memory capacity estimates in the canonical change detection task.

PubMed

Lin, Po-Han; Luck, Steven J

2012-01-01

The change detection task has become a standard method for estimating the storage capacity of visual working memory. Most researchers assume that this task isolates the properties of an active short-term storage system that can be dissociated from long-term memory systems. However, long-term memory storage may influence performance on this task. In particular, memory traces from previous trials may create proactive interference that sometimes leads to errors, thereby reducing estimated capacity. Consequently, the capacity of visual working memory may be higher than is usually thought, and correlations between capacity and other measures of cognition may reflect individual differences in proactive interference rather than individual differences in the capacity of the short-term storage system. Indeed, previous research has shown that change detection performance can be influenced by proactive interference under some conditions. The purpose of the present study was to determine whether the canonical version of the change detection task - in which the to-be-remembered information consists of simple, briefly presented features - is influenced by proactive interference. Two experiments were conducted using methods that ordinarily produce substantial evidence of proactive interference, but no proactive interference was observed. Thus, the canonical version of the change detection task can be used to assess visual working memory capacity with no meaningful influence of proactive interference.

Minimum viewing angle for visually guided ground speed control in bumblebees.

PubMed

Baird, Emily; Kornfeldt, Torill; Dacke, Marie

2010-05-01

To control flight, flying insects extract information from the pattern of visual motion generated during flight, known as optic flow. To regulate their ground speed, insects such as honeybees and Drosophila hold the rate of optic flow in the axial direction (front-to-back) constant. A consequence of this strategy is that its performance varies with the minimum viewing angle (the deviation from the frontal direction of the longitudinal axis of the insect) at which changes in axial optic flow are detected. The greater this angle, the later changes in the rate of optic flow, caused by changes in the density of the environment, will be detected. The aim of the present study is to examine the mechanisms of ground speed control in bumblebees and to identify the extent of the visual range over which optic flow for ground speed control is measured. Bumblebees were trained to fly through an experimental tunnel consisting of parallel vertical walls. Flights were recorded when (1) the distance between the tunnel walls was either 15 or 30 cm, (2) the visual texture on the tunnel walls provided either strong or weak optic flow cues and (3) the distance between the walls changed abruptly halfway along the tunnel's length. The results reveal that bumblebees regulate ground speed using optic flow cues and that changes in the rate of optic flow are detected at a minimum viewing angle of 23-30 deg., with a visual field that extends to approximately 155 deg. By measuring optic flow over a visual field that has a low minimum viewing angle, bumblebees are able to detect and respond to changes in the proximity of the environment well before they are encountered.

The Relationship Between Online Visual Representation of a Scene and Long-Term Scene Memory

ERIC Educational Resources Information Center

Hollingworth, Andrew

2005-01-01

In 3 experiments the author investigated the relationship between the online visual representation of natural scenes and long-term visual memory. In a change detection task, a target object either changed or remained the same from an initial image of a natural scene to a test image. Two types of changes were possible: rotation in depth, or…

Detecting glaucomatous change in visual fields: Analysis with an optimization framework.

PubMed

Yousefi, Siamak; Goldbaum, Michael H; Varnousfaderani, Ehsan S; Belghith, Akram; Jung, Tzyy-Ping; Medeiros, Felipe A; Zangwill, Linda M; Weinreb, Robert N; Liebmann, Jeffrey M; Girkin, Christopher A; Bowd, Christopher

2015-12-01

Detecting glaucomatous progression is an important aspect of glaucoma management. The assessment of longitudinal series of visual fields, measured using Standard Automated Perimetry (SAP), is considered the reference standard for this effort. We seek efficient techniques for determining progression from longitudinal visual fields by formulating the problem as an optimization framework, learned from a population of glaucoma data. The longitudinal data from each patient's eye were used in a convex optimization framework to find a vector that is representative of the progression direction of the sample population, as a whole. Post-hoc analysis of longitudinal visual fields across the derived vector led to optimal progression (change) detection. The proposed method was compared to recently described progression detection methods and to linear regression of instrument-defined global indices, and showed slightly higher sensitivities at the highest specificities than other methods (a clinically desirable result). The proposed approach is simpler, faster, and more efficient for detecting glaucomatous changes, compared to our previously proposed machine learning-based methods, although it provides somewhat less information. This approach has potential application in glaucoma clinics for patient monitoring and in research centers for classification of study participants. Copyright © 2015 Elsevier Inc. All rights reserved.

Testing visual short-term memory of pigeons (Columba livia) and a rhesus monkey (Macaca mulatta) with a location change detection task.

PubMed

Leising, Kenneth J; Elmore, L Caitlin; Rivera, Jacquelyne J; Magnotti, John F; Katz, Jeffrey S; Wright, Anthony A

2013-09-01

Change detection is commonly used to assess capacity (number of objects) of human visual short-term memory (VSTM). Comparisons with the performance of non-human animals completing similar tasks have shown similarities and differences in object-based VSTM, which is only one aspect ("what") of memory. Another important aspect of memory, which has received less attention, is spatial short-term memory for "where" an object is in space. In this article, we show for the first time that a monkey and pigeons can be accurately trained to identify location changes, much as humans do, in change detection tasks similar to those used to test object capacity of VSTM. The subject's task was to identify (touch/peck) an item that changed location across a brief delay. Both the monkey and pigeons showed transfer to delays longer than the training delay, to greater and smaller distance changes than in training, and to novel colors. These results are the first to demonstrate location-change detection in any non-human species and encourage comparative investigations into the nature of spatial and visual short-term memory.

The fate of object memory traces under change detection and change blindness.

PubMed

Busch, Niko A

2013-07-03

Observers often fail to detect substantial changes in a visual scene. This so-called change blindness is often taken as evidence that visual representations are sparse and volatile. This notion rests on the assumption that the failure to detect a change implies that representations of the changing objects are lost all together. However, recent evidence suggests that under change blindness, object memory representations may be formed and stored, but not retrieved. This study investigated the fate of object memory representations when changes go unnoticed. Participants were presented with scenes consisting of real world objects, one of which changed on each trial, while recording event-related potentials (ERPs). Participants were first asked to localize where the change had occurred. In an additional recognition task, participants then discriminated old objects, either from the pre-change or the post-change scene, from entirely new objects. Neural traces of object memories were studied by comparing ERPs for old and novel objects. Participants performed poorly in the detection task and often failed to recognize objects from the scene, especially pre-change objects. However, a robust old/novel effect was observed in the ERP, even when participants were change blind and did not recognize the old object. This implicit memory trace was found both for pre-change and post-change objects. These findings suggest that object memories are stored even under change blindness. Thus, visual representations may not be as sparse and volatile as previously thought. Rather, change blindness may point to a failure to retrieve and use these representations for change detection. Copyright © 2013 Elsevier B.V. All rights reserved.

Frequency doubling technology perimetry for detection of visual field progression in glaucoma: a pointwise linear regression analysis.

PubMed

Liu, Shu; Yu, Marco; Weinreb, Robert N; Lai, Gilda; Lam, Dennis Shun-Chiu; Leung, Christopher Kai-Shun

2014-05-02

We compared the detection of visual field progression and its rate of change between standard automated perimetry (SAP) and Matrix frequency doubling technology perimetry (FDTP) in glaucoma. We followed prospectively 217 eyes (179 glaucoma and 38 normal eyes) for SAP and FDTP testing at 4-month intervals for ≥36 months. Pointwise linear regression analysis was performed. A test location was considered progressing when the rate of change of visual sensitivity was ≤-1 dB/y for nonedge and ≤-2 dB/y for edge locations. Three criteria were used to define progression in an eye: ≥3 adjacent nonedge test locations (conservative), any three locations (moderate), and any two locations (liberal) progressed. The rate of change of visual sensitivity was calculated with linear mixed models. Of the 217 eyes, 6.1% and 3.9% progressed with the conservative criteria, 14.5% and 5.6% of eyes progressed with the moderate criteria, and 20.1% and 11.7% of eyes progressed with the liberal criteria by FDTP and SAP, respectively. Taking all test locations into consideration (total, 54 × 179 locations), FDTP detected more progressing locations (176) than SAP (103, P < 0.001). The rate of change of visual field mean deviation (MD) was significantly faster for FDTP (all with P < 0.001). No eyes showed progression in the normal group using the conservative and the moderate criteria. With a faster rate of change of visual sensitivity, FDTP detected more progressing eyes than SAP at a comparable level of specificity. Frequency doubling technology perimetry can provide a useful alternative to monitor glaucoma progression.

Visual assessment of brain magnetic resonance imaging detects injury to cognitive regulatory sites in patients with heart failure.

PubMed

Pan, Alan; Kumar, Rajesh; Macey, Paul M; Fonarow, Gregg C; Harper, Ronald M; Woo, Mary A

2013-02-01

Heart failure (HF) patients exhibit depression and executive function impairments that contribute to HF mortality. Using specialized magnetic resonance imaging (MRI) analysis procedures, brain changes appear in areas regulating these functions (mammillary bodies, hippocampi, and frontal cortex). However, specialized MRI procedures are not part of standard clinical assessment for HF (which is usually a visual evaluation), and it is unclear whether visual MRI examination can detect changes in these structures. Using brain MRI, we visually examined the mammillary bodies and frontal cortex for global and hippocampi for global and regional tissue changes in 17 HF and 50 control subjects. Significantly global changes emerged in the right mammillary body (HF 1.18 ± 1.13 vs control 0.52 ± 0.74; P = .024), right hippocampus (HF 1.53 ± 0.94 vs control 0.80 ± 0.86; P = .005), and left frontal cortex (HF 1.76 ± 1.03 vs control 1.24 ± 0.77; P = .034). Comparison of the visual method with specialized MRI techniques corroborates right hippocampal and left frontal cortical, but not mammillary body, tissue changes. Visual examination of brain MRI can detect damage in HF in areas regulating depression and executive function, including the right hippocampus and left frontal cortex. Visual MRI assessment in HF may facilitate evaluation of injury to these structures and the assessment of the impact of potential treatments for this damage. Copyright © 2013 Elsevier Inc. All rights reserved.

Visual cortex in aging and Alzheimer's disease: changes in visual field maps and population receptive fields

PubMed Central

Brewer, Alyssa A.; Barton, Brian

2012-01-01

Although several studies have suggested that cortical alterations underlie such age-related visual deficits as decreased acuity, little is known about what changes actually occur in visual cortex during healthy aging. Two recent studies showed changes in primary visual cortex (V1) during normal aging; however, no studies have characterized the effects of aging on visual cortex beyond V1, important measurements both for understanding the aging process and for comparison to changes in age-related diseases. Similarly, there is almost no information about changes in visual cortex in Alzheimer's disease (AD), the most common form of dementia. Because visual deficits are often reported as one of the first symptoms of AD, measurements of such changes in the visual cortex of AD patients might improve our understanding of how the visual system is affected by neurodegeneration as well as aid early detection, accurate diagnosis and timely treatment of AD. Here we use fMRI to first compare the visual field map (VFM) organization and population receptive fields (pRFs) between young adults and healthy aging subjects for occipital VFMs V1, V2, V3, and hV4. Healthy aging subjects do not show major VFM organizational deficits, but do have reduced surface area and increased pRF sizes in the foveal representations of V1, V2, and hV4 relative to healthy young control subjects. These measurements are consistent with behavioral deficits seen in healthy aging. We then demonstrate the feasibility and first characterization of these measurements in two patients with mild AD, which reveal potential changes in visual cortex as part of the pathophysiology of AD. Our data aid in our understanding of the changes in the visual processing pathways in normal aging and provide the foundation for future research into earlier and more definitive detection of AD. PMID:24570669

Communal visual histories to detect environmental change in northern areas: Examples of emerging North American and Eurasian practices.

PubMed

Mustonen, Tero

2015-12-01

This article explores the pioneering potential of communal visual-optic histories which are recorded, painted, documented, or otherwise expressed. These materials provide collective meanings of an image or visual material within a specific cultural group. They potentially provide a new method for monitoring and documenting changes to ecosystem health and species distribution, which can effectively inform society and decision makers of Arctic change. These visual histories can be positioned in a continuum that extends from rock art to digital photography. They find their expressions in forms ranging from images to the oral recording of knowledge and operate on a given cultural context. For monitoring efforts in the changing boreal zone and Arctic, a respectful engagement with visual histories can reveal emerging aspects of change. The examples from North America and case studies from Eurasia in this article include Inuit sea ice observations, Yu'pik visual traditions of masks, fish die-offs in a sub-boreal catchment area, permafrost melt in the Siberian tundra and early, first detection of a scarabaeid beetle outbreak, a Southern species in the Skolt Sámi area. The pros and cons of using these histories and their reliability are reviewed.

The Objective Identification and Quantification of Interstitial Lung Abnormalities in Smokers.

PubMed

Ash, Samuel Y; Harmouche, Rola; Ross, James C; Diaz, Alejandro A; Hunninghake, Gary M; Putman, Rachel K; Onieva, Jorge; Martinez, Fernando J; Choi, Augustine M; Lynch, David A; Hatabu, Hiroto; Rosas, Ivan O; Estepar, Raul San Jose; Washko, George R

2017-08-01

Previous investigation suggests that visually detected interstitial changes in the lung parenchyma of smokers are highly clinically relevant and predict outcomes, including death. Visual subjective analysis to detect these changes is time-consuming, insensitive to subtle changes, and requires training to enhance reproducibility. Objective detection of such changes could provide a method of disease identification without these limitations. The goal of this study was to develop and test a fully automated image processing tool to objectively identify radiographic features associated with interstitial abnormalities in the computed tomography scans of a large cohort of smokers. An automated tool that uses local histogram analysis combined with distance from the pleural surface was used to detect radiographic features consistent with interstitial lung abnormalities in computed tomography scans from 2257 individuals from the Genetic Epidemiology of COPD study, a longitudinal observational study of smokers. The sensitivity and specificity of this tool was determined based on its ability to detect the visually identified presence of these abnormalities. The tool had a sensitivity of 87.8% and a specificity of 57.5% for the detection of interstitial lung abnormalities, with a c-statistic of 0.82, and was 100% sensitive and 56.7% specific for the detection of the visual subtype of interstitial abnormalities called fibrotic parenchymal abnormalities, with a c-statistic of 0.89. In smokers, a fully automated image processing tool is able to identify those individuals who have interstitial lung abnormalities with moderate sensitivity and specificity. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

The Development of Change Blindness: Children's Attentional Priorities whilst Viewing Naturalistic Scenes

ERIC Educational Resources Information Center

Fletcher-Watson, S.; Collis, J. M.; Findlay, J. M.; Leekam, S. R.

2009-01-01

Change blindness describes the surprising difficulty of detecting large changes in visual scenes when changes occur during a visual disruption. In order to study the developmental course of this phenomenon, a modified version of the flicker paradigm, based on Rensink, O'Regan & Clark (1997), was given to three groups of children aged 6-12 years…

Nonexplicit change detection in complex dynamic settings: what eye movements reveal.

PubMed

Vachon, François; Vallières, Benoît R; Jones, Dylan M; Tremblay, Sébastien

2012-12-01

We employed a computer-controlled command-and-control (C2) simulation and recorded eye movements to examine the extent and nature of the inability to detect critical changes in dynamic displays when change detection is implicit (i.e., requires no explicit report) to the operator's task. Change blindness-the failure to notice significant changes to a visual scene-may have dire consequences on performance in C2 and surveillance operations. Participants performed a radar-based risk-assessment task involving multiple subtasks. Although participants were not required to explicitly report critical changes to the operational display, change detection was critical in informing decision making. Participants' eye movements were used as an index of visual attention across the display. Nonfixated (i.e., unattended) changes were more likely to be missed than were fixated (i.e., attended) changes, supporting the idea that focused attention is necessary for conscious change detection. The finding of significant pupil dilation for changes undetected but fixated suggests that attended changes can nonetheless be missed because of a failure of attentional processes. Change blindness in complex dynamic displays takes the form of failures in establishing task-appropriate patterns of attentional allocation. These findings have implications in the design of change-detection support tools for dynamic displays and work procedure in C2 and surveillance.

Selective maintenance in visual working memory does not require sustained visual attention.

PubMed

Hollingworth, Andrew; Maxcey-Richard, Ashleigh M

2013-08-01

In four experiments, we tested whether sustained visual attention is required for the selective maintenance of objects in visual working memory (VWM). Participants performed a color change-detection task. During the retention interval, a valid cue indicated the item that would be tested. Change-detection performance was higher in the valid-cue condition than in a neutral-cue control condition. To probe the role of visual attention in the cuing effect, on half of the trials, a difficult search task was inserted after the cue, precluding sustained attention on the cued item. The addition of the search task produced no observable decrement in the magnitude of the cuing effect. In a complementary test, search efficiency was not impaired by simultaneously prioritizing an object for retention in VWM. The results demonstrate that selective maintenance in VWM can be dissociated from the locus of visual attention. 2013 APA, all rights reserved

Vision restoration through extrastriate stimulation in patients with visual field defects: a double-blind and randomized experimental study.

PubMed

Jobke, Sandra; Kasten, Erich; Sabel, Bernhard A

2009-01-01

. Vision restoration therapy (VRT) to treat visual field defects used single-point visual stimulation in areas of residual vision up to now. The question arises if the efficiency of restoration can be increased when the entire region of blindness is trained by a visual stimulus aimed at activating extrastriate pathways (extrastriate VRT). . In this crossover study, 18 patients with visual field defects with prior VRT experience were treated with 2 training paradigms. Group 1 (n = 8) first used extrastriate VRT followed by conventional standard VRT. Group 2 (n = 10) trained in reverse order. Visual field size was assessed with computer-based perimetry and subjective vision with the National Eye Institute Visual Function Questionnaire (NEI-VFQ). . In group 1, stimulus detection in high-resolution perimetry (HRP) improved by 5.9% (P < .01) after extrastriate VRT. After the second training period (standard VRT), detection further improved by 1.8% (P = .093). In group 2, detection performance improved after standard VRT by 2.9% (P < .05) and after extrastriate VRT by 2.9% (P < .05). Detection performance increased twice as much after extrastriate VRT (4.2%) than after standard VRT (2.4%; P < .05). All changes in fixation performance were unrelated to detection improvements. NEI-VFQ did not show any significant changes. . Greater improvement after extrastriate VRT is interpreted as an activation of extrastriate pathways by massive "spiral-like" stimulation. These pathways bypass the damaged visual cortex, stimulating extrastriate cortical regions, and are thought to be involved in blindsight.

Supporting dynamic change detection: using the right tool for the task.

PubMed

Vallières, Benoît R; Hodgetts, Helen M; Vachon, François; Tremblay, Sébastien

2016-01-01

Detecting task-relevant changes in a visual scene is necessary for successfully monitoring and managing dynamic command and control situations. Change blindness-the failure to notice visual changes-is an important source of human error. Change History EXplicit (CHEX) is a tool developed to aid change detection and maintain situation awareness; and in the current study we test the generality of its ability to facilitate the detection of changes when this subtask is embedded within a broader dynamic decision-making task. A multitasking air-warfare simulation required participants to perform radar-based subtasks, for which change detection was a necessary aspect of the higher-order goal of protecting one's own ship. In this task, however, CHEX rendered the operator even more vulnerable to attentional failures in change detection and increased perceived workload. Such support was only effective when participants performed a change detection task without concurrent subtasks. Results are interpreted in terms of the NSEEV model of attention behavior (Steelman, McCarley, & Wickens, Hum. Factors 53:142-153, 2011; J. Exp. Psychol. Appl. 19:403-419, 2013), and suggest that decision aids for use in multitasking contexts must be designed to fit within the available workload capacity of the user so that they may truly augment cognition.

An eye tracking investigation of color-location binding in infants' visual short-term memory.

PubMed

Oakes, Lisa M; Baumgartner, Heidi A; Kanjlia, Shipra; Luck, Steven J

2017-01-01

Two experiments examined 8- and 10-month-old infants' ( N = 71) binding of object identity (color) and location information in visual short-term memory (VSTM) using a one-shot change detection task . Building on previous work using the simultaneous streams change detection task, we confirmed that 8- and 10-month-old infants are sensitive to changes in binding between identity and location in VSTM. Further, we demonstrated that infants recognize specifically what changed in these events. Thus, infants' VSTM for binding is robust and can be observed in different procedures and with different stimuli.

Change Deafness and the Organizational Properties of Sounds

ERIC Educational Resources Information Center

Gregg, Melissa K.; Samuel, Arthur G.

2008-01-01

Change blindness, or the failure to detect (often large) changes to visual scenes, has been demonstrated in a variety of different situations. Failures to detect auditory changes are far less studied, and thus little is known about the nature of change deafness. Five experiments were conducted to explore the processes involved in change deafness…

Familiarity Enhances Visual Working Memory for Faces

ERIC Educational Resources Information Center

Jackson, Margaret C.; Raymond, Jane E.

2008-01-01

Although it is intuitive that familiarity with complex visual objects should aid their preservation in visual working memory (WM), empirical evidence for this is lacking. This study used a conventional change-detection procedure to assess visual WM for unfamiliar and famous faces in healthy adults. Across experiments, faces were upright or…

Contingent capture of involuntary visual spatial attention does not differ between normally hearing children and proficient cochlear implant users.

PubMed

Kamke, Marc R; Van Luyn, Jeanette; Constantinescu, Gabriella; Harris, Jill

2014-01-01

Evidence suggests that deafness-induced changes in visual perception, cognition and attention may compensate for a hearing loss. Such alterations, however, may also negatively influence adaptation to a cochlear implant. This study investigated whether involuntary attentional capture by salient visual stimuli is altered in children who use a cochlear implant. Thirteen experienced implant users (aged 8-16 years) and age-matched normally hearing children were presented with a rapid sequence of simultaneous visual and auditory events. Participants were tasked with detecting numbers presented in a specified color and identifying a change in the tonal frequency whilst ignoring irrelevant visual distractors. Compared to visual distractors that did not possess the target-defining characteristic, target-colored distractors were associated with a decrement in visual performance (response time and accuracy), demonstrating a contingent capture of involuntary attention. Visual distractors did not, however, impair auditory task performance. Importantly, detection performance for the visual and auditory targets did not differ between the groups. These results suggest that proficient cochlear implant users demonstrate normal capture of visuospatial attention by stimuli that match top-down control settings.

Changes in Women’s Facial Skin Color over the Ovulatory Cycle are Not Detectable by the Human Visual System

PubMed Central

Burriss, Robert P.; Troscianko, Jolyon; Lovell, P. George; Fulford, Anthony J. C.; Stevens, Martin; Quigley, Rachael; Payne, Jenny; Saxton, Tamsin K.; Rowland, Hannah M.

2015-01-01

Human ovulation is not advertised, as it is in several primate species, by conspicuous sexual swellings. However, there is increasing evidence that the attractiveness of women’s body odor, voice, and facial appearance peak during the fertile phase of their ovulatory cycle. Cycle effects on facial attractiveness may be underpinned by changes in facial skin color, but it is not clear if skin color varies cyclically in humans or if any changes are detectable. To test these questions we photographed women daily for at least one cycle. Changes in facial skin redness and luminance were then quantified by mapping the digital images to human long, medium, and shortwave visual receptors. We find cyclic variation in skin redness, but not luminance. Redness decreases rapidly after menstrual onset, increases in the days before ovulation, and remains high through the luteal phase. However, we also show that this variation is unlikely to be detectable by the human visual system. We conclude that changes in skin color are not responsible for the effects of the ovulatory cycle on women’s attractiveness. PMID:26134671

Changes in Women's Facial Skin Color over the Ovulatory Cycle are Not Detectable by the Human Visual System.

PubMed

Burriss, Robert P; Troscianko, Jolyon; Lovell, P George; Fulford, Anthony J C; Stevens, Martin; Quigley, Rachael; Payne, Jenny; Saxton, Tamsin K; Rowland, Hannah M

2015-01-01

Human ovulation is not advertised, as it is in several primate species, by conspicuous sexual swellings. However, there is increasing evidence that the attractiveness of women's body odor, voice, and facial appearance peak during the fertile phase of their ovulatory cycle. Cycle effects on facial attractiveness may be underpinned by changes in facial skin color, but it is not clear if skin color varies cyclically in humans or if any changes are detectable. To test these questions we photographed women daily for at least one cycle. Changes in facial skin redness and luminance were then quantified by mapping the digital images to human long, medium, and shortwave visual receptors. We find cyclic variation in skin redness, but not luminance. Redness decreases rapidly after menstrual onset, increases in the days before ovulation, and remains high through the luteal phase. However, we also show that this variation is unlikely to be detectable by the human visual system. We conclude that changes in skin color are not responsible for the effects of the ovulatory cycle on women's attractiveness.

Visual search for changes in scenes creates long-term, incidental memory traces.

PubMed

Utochkin, Igor S; Wolfe, Jeremy M

2018-05-01

Humans are very good at remembering large numbers of scenes over substantial periods of time. But how good are they at remembering changes to scenes? In this study, we tested scene memory and change detection two weeks after initial scene learning. In Experiments 1-3, scenes were learned incidentally during visual search for change. In Experiment 4, observers explicitly memorized scenes. At test, after two weeks observers were asked to discriminate old from new scenes, to recall a change that they had detected in the study phase, or to detect a newly introduced change in the memorization experiment. Next, they performed a change detection task, usually looking for the same change as in the study period. Scene recognition memory was found to be similar in all experiments, regardless of the study task. In Experiment 1, more difficult change detection produced better scene memory. Experiments 2 and 3 supported a "depth-of-processing" account for the effects of initial search and change detection on incidental memory for scenes. Of most interest, change detection was faster during the test phase than during the study phase, even when the observer had no explicit memory of having found that change previously. This result was replicated in two of our three change detection experiments. We conclude that scenes can be encoded incidentally as well as explicitly and that changes in those scenes can leave measurable traces even if they are not explicitly recalled.

Thermographic visualization of the superficial vein and extravasation using the temperature gradient produced by the injected materials

NASA Astrophysics Data System (ADS)

Nakamura, Katsumasa; Sasaki, Tomonari; Ohga, Saiji; Yoshitake, Tadamasa; Terashima, Kotaro; Asai, Kaori; Matsumoto, Keiji; Shinoto, Makoto; Shioyama, Yoshiyuki; Nishie, Akihoro; Honda, Hiroshi

2014-11-01

There are few effective methods to detect or prevent the extravasation of injected materials such as chemotherapeutic agents and radiographic contrast materials. To investigate whether a thermographic camera could visualize the superficial vein and extravasation using the temperature gradient produced by the injected materials, an infrared thermographic camera with a high resolution of 0.04 °C was used. At the room temperature of 26 °C, thermal images and the time course of the temperature changes of a paraffin phantom embedded with rubber tubes (diameter 3.2 mm, wall thickness 0.8 mm) were evaluated after the tubes were filled with water at 15 °C or 25 °C. The rubber tubes were embedded at depths of 0 mm, 1.5 mm, and 3.0 mm from the surface of the phantom. Temperature changes were visualized in the areas of the phantom where the tubes were embedded. In general, changes were more clearly detected when greater temperature differences between the phantom and the water and shallower tube locations were employed. The temperature changes of the surface of a volunteer's arm were also examined after a bolus injection of physiological saline into the dorsal hand vein or the subcutaneous space. The injection of 5 ml room-temperature (26 °C) saline into the dorsal hand vein enabled the visualization of the vein. When 3 ml of room-temperature saline was injected through the vein into the subcutaneous space, extravasation was detected without any visualization of the vein. The subtraction image before and after the injection clearly showed the temperature changes induced by the saline. Thermography may thus be useful as a monitoring system to detect extravasation of the injected materials.

Effects of divided attention and operating room noise on perception of pulse oximeter pitch changes: a laboratory study.

PubMed

Stevenson, Ryan A; Schlesinger, Joseph J; Wallace, Mark T

2013-02-01

Anesthesiology requires performing visually oriented procedures while monitoring auditory information about a patient's vital signs. A concern in operating room environments is the amount of competing information and the effects that divided attention has on patient monitoring, such as detecting auditory changes in arterial oxygen saturation via pulse oximetry. The authors measured the impact of visual attentional load and auditory background noise on the ability of anesthesia residents to monitor the pulse oximeter auditory display in a laboratory setting. Accuracies and response times were recorded reflecting anesthesiologists' abilities to detect changes in oxygen saturation across three levels of visual attention in quiet and with noise. Results show that visual attentional load substantially affects the ability to detect changes in oxygen saturation concentrations conveyed by auditory cues signaling 99 and 98% saturation. These effects are compounded by auditory noise, up to a 17% decline in performance. These deficits are seen in the ability to accurately detect a change in oxygen saturation and in speed of response. Most anesthesia accidents are initiated by small errors that cascade into serious events. Lack of monitor vigilance and inattention are two of the more commonly cited factors. Reducing such errors is thus a priority for improving patient safety. Specifically, efforts to reduce distractors and decrease background noise should be considered during induction and emergence, periods of especially high risk, when anesthesiologists has to attend to many tasks and are thus susceptible to error.

Detecting gradual visual changes in colour and brightness agnosia: a double dissociation.

PubMed

Nijboer, Tanja C W; te Pas, Susan F; van der Smagt, Maarten J

2011-03-09

Two patients, one with colour agnosia and one with brightness agnosia, performed a task that required the detection of gradual temporal changes in colour and brightness. The results for these patients, who showed anaverage or an above-average performance on several tasks designed to test low-level colour and luminance (contrast) perception in the spatial domain, yielded a double dissociation; the brightness agnosic patient was within the normal range for the coloured stimuli, but much slower to detect brightness differences, whereas the colour agnosic patient was within the normal range for the achromatic stimuli, but much slower for the coloured stimuli. These results suggest that a modality-specific impairment in the detection of gradual temporal changes might be related to, if not underlie, the phenomenon of visual agnosia.

Metacognitive monitoring and control in visual change detection: Implications for situation awareness and cognitive control

PubMed Central

McAnally, Ken I.; Morris, Adam P.; Best, Christopher

2017-01-01

Metacognitive monitoring and control of situation awareness (SA) are important for a range of safety-critical roles (e.g., air traffic control, military command and control). We examined the factors affecting these processes using a visual change detection task that included representative tactical displays. SA was assessed by asking novice observers to detect changes to a tactical display. Metacognitive monitoring was assessed by asking observers to estimate the probability that they would correctly detect a change, either after study of the display and before the change (judgement of learning; JOL) or after the change and detection response (judgement of performance; JOP). In Experiment 1, observers failed to detect some changes to the display, indicating imperfect SA, but JOPs were reasonably well calibrated to objective performance. Experiment 2 examined JOLs and JOPs in two task contexts: with study-time limits imposed by the task or with self-pacing to meet specified performance targets. JOPs were well calibrated in both conditions as were JOLs for high performance targets. In summary, observers had limited SA, but good insight about their performance and learning for high performance targets and allocated study time appropriately. PMID:28915244

Changes in the Capacity of Visual Working Memory in 5- to 10-Year-Olds

ERIC Educational Resources Information Center

Riggs, Kevin J.; McTaggart, James; Simpson, Andrew; Freeman, Richard P. J.

2006-01-01

Using the Luck and Vogel change detection paradigm, we sought to investigate the capacity of visual working memory in 5-, 7-, and 10-year-olds. We found that performance on the task improved significantly with age and also obtained evidence that the capacity of visual working memory approximately doubles between 5 and 10 years of age, where it…

A visual stethoscope to detect the position of the tracheal tube.

PubMed

Kato, Hiromi; Suzuki, Akira; Nakajima, Yoshiki; Makino, Hiroshi; Sanjo, Yoshimitsu; Nakai, Takayoshi; Shiraishi, Yoshito; Katoh, Takasumi; Sato, Shigehito

2009-12-01

Advancing a tracheal tube into the bronchus produces unilateral breath sounds. We created a Visual Stethoscope that allows real-time fast Fourier transformation of the sound signal and 3-dimensional (frequency-amplitude-time) color rendering of the results on a personal computer with simultaneous processing of 2 individual sound signals. The aim of this study was to evaluate whether the Visual Stethoscope can detect bronchial intubation in comparison with auscultation. After induction of general anesthesia, the trachea was intubated with a tracheal tube. The distance from the incisors to the carina was measured using a fiberoptic bronchoscope. While the anesthesiologist advanced the tracheal tube from the trachea to the bronchus, another anesthesiologist auscultated breath sounds to detect changes of the breath sounds and/or disappearance of bilateral breath sounds for every 1 cm that the tracheal tube was advanced. Two precordial stethoscopes placed at the left and right sides of the chest were used to record breath sounds simultaneously. Subsequently, at a later date, we randomly entered the recorded breath sounds into the Visual Stethoscope. The same anesthesiologist observed the visualized breath sounds on the personal computer screen processed by the Visual Stethoscope to examine changes of breath sounds and/or disappearance of bilateral breath sound. We compared the decision made based on auscultation with that made based on the results of the visualized breath sounds using the Visual Stethoscope. Thirty patients were enrolled in the study. When irregular breath sounds were auscultated, the tip of the tracheal tube was located at 0.6 +/- 1.2 cm on the bronchial side of the carina. Using the Visual Stethoscope, when there were any changes of the shape of the visualized breath sound, the tube was located at 0.4 +/- 0.8 cm on the tracheal side of the carina (P < 0.01). When unilateral breath sounds were auscultated, the tube was located at 2.6 +/- 1.2 cm on the bronchial side of the carina. The tube was also located at 2.3 +/- 1.0 cm on the bronchial side of the carina when a unilateral shape of visualized breath sounds was obtained using the Visual Stethoscope (not significant). During advancement of the tracheal tube, alterations of the shape of the visualized breath sounds using the Visual Stethoscope appeared before the changes of the breath sounds were detected by auscultation. Bilateral breath sounds disappeared when the tip of the tracheal tube was advanced beyond the carina in both groups.

Reduced change blindness suggests enhanced attention to detail in individuals with autism.

PubMed

Smith, Hayley; Milne, Elizabeth

2009-03-01

The phenomenon of change blindness illustrates that a limited number of items within the visual scene are attended to at any one time. It has been suggested that individuals with autism focus attention on less contextually relevant aspects of the visual scene, show superior perceptual discrimination and notice details which are often ignored by typical observers. In this study we investigated change blindness in autism by asking participants to detect continuity errors deliberately introduced into a short film. Whether the continuity errors involved central/marginal or social/non-social aspects of the visual scene was varied. Thirty adolescent participants, 15 with autistic spectrum disorder (ASD) and 15 typically developing (TD) controls participated. The participants with ASD detected significantly more errors than the TD participants. Both groups identified more errors involving central rather than marginal aspects of the scene, although this effect was larger in the TD participants. There was no difference in the number of social or non-social errors detected by either group of participants. In line with previous data suggesting an abnormally broad attentional spotlight and enhanced perceptual function in individuals with ASD, the results of this study suggest enhanced awareness of the visual scene in ASD. The results of this study could reflect superior top-down control of visual search in autism, enhanced perceptual function, or inefficient filtering of visual information in ASD.

Randomized trial of the ForeseeHome monitoring device for early detection of neovascular age-related macular degeneration. The HOme Monitoring of the Eye (HOME) study design - HOME Study report number 1.

PubMed

Chew, Emily Y; Clemons, Traci E; Bressler, Susan B; Elman, Michael J; Danis, Ronald P; Domalpally, Amitha; Heier, Jeffrey S; Kim, Judy E; Garfinkel, Richard A

2014-03-01

To evaluate the effects of a home-monitoring device with tele-monitoring compared with standard care in detection of progression to choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD), the leading cause of blindness in the US. Participants, aged 55 to 90 years, at high risk of developing CNV associated with AMD were recruited to the HOme Monitoring of Eye (HOME) Study, an unmasked, multi-center, randomized trial of the ForeseeHome (FH) device plus standard care vs. standard care alone. The FH device utilizes preferential hyperacuity perimetry and tele-monitoring to detect changes in vision function associated with development of CNV, potentially prior to symptom and visual acuity loss. After establishing baseline measurements, subsequent changes on follow-up are detected by the device, causing the monitoring center to alert the clinical center to recall participants for an exam. Standard care consists of instructions for self-monitoring visual changes with subsequent self-report to the clinical center. The primary objective of this study is to determine whether home monitoring plus standard care in comparison with standard care alone, results in earlier detection of incident CNV with better present visual acuity. The primary outcome is the decline in visual acuity at CNV diagnosis from baseline. Detection of CNV prior to substantial vision loss is critical as vision outcome following anti-angiogenic therapy is dependent on the visual acuity at initiation of treatment. HOME Study is the first large scale study to test the use of home tele-monitoring system in the management of AMD patients. Published by Elsevier Inc.

Implicit Binding of Facial Features During Change Blindness

PubMed Central

Lyyra, Pessi; Mäkelä, Hanna; Hietanen, Jari K.; Astikainen, Piia

2014-01-01

Change blindness refers to the inability to detect visual changes if introduced together with an eye-movement, blink, flash of light, or with distracting stimuli. Evidence of implicit detection of changed visual features during change blindness has been reported in a number of studies using both behavioral and neurophysiological measurements. However, it is not known whether implicit detection occurs only at the level of single features or whether complex organizations of features can be implicitly detected as well. We tested this in adult humans using intact and scrambled versions of schematic faces as stimuli in a change blindness paradigm while recording event-related potentials (ERPs). An enlargement of the face-sensitive N170 ERP component was observed at the right temporal electrode site to changes from scrambled to intact faces, even if the participants were not consciously able to report such changes (change blindness). Similarly, the disintegration of an intact face to scrambled features resulted in attenuated N170 responses during change blindness. Other ERP deflections were modulated by changes, but unlike the N170 component, they were indifferent to the direction of the change. The bidirectional modulation of the N170 component during change blindness suggests that implicit change detection can also occur at the level of complex features in the case of facial stimuli. PMID:24498165

Implicit binding of facial features during change blindness.

PubMed

Lyyra, Pessi; Mäkelä, Hanna; Hietanen, Jari K; Astikainen, Piia

2014-01-01

Change blindness refers to the inability to detect visual changes if introduced together with an eye-movement, blink, flash of light, or with distracting stimuli. Evidence of implicit detection of changed visual features during change blindness has been reported in a number of studies using both behavioral and neurophysiological measurements. However, it is not known whether implicit detection occurs only at the level of single features or whether complex organizations of features can be implicitly detected as well. We tested this in adult humans using intact and scrambled versions of schematic faces as stimuli in a change blindness paradigm while recording event-related potentials (ERPs). An enlargement of the face-sensitive N170 ERP component was observed at the right temporal electrode site to changes from scrambled to intact faces, even if the participants were not consciously able to report such changes (change blindness). Similarly, the disintegration of an intact face to scrambled features resulted in attenuated N170 responses during change blindness. Other ERP deflections were modulated by changes, but unlike the N170 component, they were indifferent to the direction of the change. The bidirectional modulation of the N170 component during change blindness suggests that implicit change detection can also occur at the level of complex features in the case of facial stimuli.

Drivers' and non-drivers' performance in a change detection task with static driving scenes: is there a benefit of experience?

PubMed

Zhao, Nan; Chen, Wenfeng; Xuan, Yuming; Mehler, Bruce; Reimer, Bryan; Fu, Xiaolan

2014-01-01

The 'looked-but-failed-to-see' phenomenon is crucial to driving safety. Previous research utilising change detection tasks related to driving has reported inconsistent effects of driver experience on the ability to detect changes in static driving scenes. Reviewing these conflicting results, we suggest that drivers' increased ability to detect changes will only appear when the task requires a pattern of visual attention distribution typical of actual driving. By adding a distant fixation point on the road image, we developed a modified change blindness paradigm and measured detection performance of drivers and non-drivers. Drivers performed better than non-drivers only in scenes with a fixation point. Furthermore, experience effect interacted with the location of the change and the relevance of the change to driving. These results suggest that learning associated with driving experience reflects increased skill in the efficient distribution of visual attention across both the central focus area and peripheral objects. This article provides an explanation for the previously conflicting reports of driving experience effects in change detection tasks. We observed a measurable benefit of experience in static driving scenes, using a modified change blindness paradigm. These results have translational opportunities for picture-based training and testing tools to improve driver skill.

Effects of VDT workstation lighting conditions on operator visual workload.

PubMed

Lin, Chiuhsiang Joe; Feng, Wen-Yang; Chao, Chin-Jung; Tseng, Feng-Yi

2008-04-01

Industrial lighting covers a wide range of different characteristics of working interiors and work tasks. This study investigated the effects of illumination on visual workload in visual display terminal (VDT) workstation. Ten college students (5 males and 5 females) were recruited as participants to perform VDT signal detection tasks. A randomized block design was utilized with four light colors (red, blue, green and white), two ambient illumination levels (20 lux and 340 lux), with the subject as the block. The dependent variables were the change of critical fusion frequency (CFF), visual acuity, reaction time of targets detection, error rates, and rating scores in a subjective questionnaire. The study results showed that both visual acuity and the subjective visual fatigue were significantly affected by the color of light. The illumination had significant effect on CFF threshold change and reaction time. Subjects prefer to perform VDT task under blue and white lights than green and red. Based on these findings, the study discusses and suggests ways of color lighting and ambient illumination to promote operators' visual performance and prevent visual fatigue effectively.

Selective Maintenance in Visual Working Memory Does Not Require Sustained Visual Attention

PubMed Central

Hollingworth, Andrew; Maxcey-Richard, Ashleigh M.

2012-01-01

In four experiments, we tested whether sustained visual attention is required for the selective maintenance of objects in VWM. Participants performed a color change-detection task. During the retention interval, a valid cue indicated the item that would be tested. Change detection performance was higher in the valid-cue condition than in a neutral-cue control condition. To probe the role of visual attention in the cuing effect, on half of the trials, a difficult search task was inserted after the cue, precluding sustained attention on the cued item. The addition of the search task produced no observable decrement in the magnitude of the cuing effect. In a complementary test, search efficiency was not impaired by simultaneously prioritizing an object for retention in VWM. The results demonstrate that selective maintenance in VWM can be dissociated from the locus of visual attention. PMID:23067118

Rendering visual events as sounds: Spatial attention capture by auditory augmented reality.

PubMed

Stone, Scott A; Tata, Matthew S

2017-01-01

Many salient visual events tend to coincide with auditory events, such as seeing and hearing a car pass by. Information from the visual and auditory senses can be used to create a stable percept of the stimulus. Having access to related coincident visual and auditory information can help for spatial tasks such as localization. However not all visual information has analogous auditory percepts, such as viewing a computer monitor. Here, we describe a system capable of detecting and augmenting visual salient events into localizable auditory events. The system uses a neuromorphic camera (DAVIS 240B) to detect logarithmic changes of brightness intensity in the scene, which can be interpreted as salient visual events. Participants were blindfolded and asked to use the device to detect new objects in the scene, as well as determine direction of motion for a moving visual object. Results suggest the system is robust enough to allow for the simple detection of new salient stimuli, as well accurately encoding direction of visual motion. Future successes are probable as neuromorphic devices are likely to become faster and smaller in the future, making this system much more feasible.

Rendering visual events as sounds: Spatial attention capture by auditory augmented reality

PubMed Central

Tata, Matthew S.

2017-01-01

Many salient visual events tend to coincide with auditory events, such as seeing and hearing a car pass by. Information from the visual and auditory senses can be used to create a stable percept of the stimulus. Having access to related coincident visual and auditory information can help for spatial tasks such as localization. However not all visual information has analogous auditory percepts, such as viewing a computer monitor. Here, we describe a system capable of detecting and augmenting visual salient events into localizable auditory events. The system uses a neuromorphic camera (DAVIS 240B) to detect logarithmic changes of brightness intensity in the scene, which can be interpreted as salient visual events. Participants were blindfolded and asked to use the device to detect new objects in the scene, as well as determine direction of motion for a moving visual object. Results suggest the system is robust enough to allow for the simple detection of new salient stimuli, as well accurately encoding direction of visual motion. Future successes are probable as neuromorphic devices are likely to become faster and smaller in the future, making this system much more feasible. PMID:28792518

Object form discontinuity facilitates displacement discrimination across saccades.

PubMed

Demeyer, Maarten; De Graef, Peter; Wagemans, Johan; Verfaillie, Karl

2010-06-01

Stimulus displacements coinciding with a saccadic eye movement are poorly detected by human observers. In recent years, converging evidence has shown that this phenomenon does not result from poor transsaccadic retention of presaccadic stimulus position information, but from the visual system's efforts to spatially align presaccadic and postsaccadic perception on the basis of visual landmarks. It is known that this process can be disrupted, and transsaccadic displacement detection performance can be improved, by briefly blanking the stimulus display during and immediately after the saccade. In the present study, we investigated whether this improvement could also follow from a discontinuity in the task-irrelevant form of the displaced stimulus. We observed this to be the case: Subjects more accurately identified the direction of intrasaccadic displacements when the displaced stimulus simultaneously changed form, compared to conditions without a form change. However, larger improvements were still observed under blanking conditions. In a second experiment, we show that facilitation induced by form changes and blanks can combine. We conclude that a strong assumption of visual stability underlies the suppression of transsaccadic change detection performance, the rejection of which generalizes from stimulus form to stimulus position.

Feature binding in visual short-term memory is unaffected by task-irrelevant changes of location, shape, and color.

PubMed

Logie, Robert H; Brockmole, James R; Jaswal, Snehlata

2011-01-01

Three experiments used a change detection paradigm across a range of study-test intervals to address the respective contributions of location, shape, and color to the formation of bindings of features in sensory memory and visual short-term memory (VSTM). In Experiment 1, location was designated task irrelevant and was randomized between study and test displays. The task was to detect changes in the bindings between shape and color. In Experiments 2 and 3, shape and color, respectively, were task irrelevant and randomized, with bindings tested between location and color (Experiment 2) and location and shape (Experiment 3). At shorter study-test intervals, randomizing location was most disruptive, followed by shape and then color. At longer intervals, randomizing any task-irrelevant feature had no impact on change detection for bindings between features, and location had no special role. Results suggest that location is crucial for initial perceptual binding but loses that special status once representations are formed in VSTM, which operates according to different principles, than do visual attention and perception.

Do Experts and Novices Direct Attention Differently in Examining Physics Diagrams? A Study of Change Detection Using the Flicker Technique

ERIC Educational Resources Information Center

Morphew, Jason W.; Mestre, Jose P.; Ross, Brian H.; Strand, Natalie E.

2015-01-01

It is known that experts identify or perceive meaningful patterns in visual stimuli related to their domain of expertise. This study explores the speed with which experts and novices detect changes in physics diagrams. Since change detection depends on where individuals direct their attention, differences in the speed with which experts and…

The trait of sensory processing sensitivity and neural responses to changes in visual scenes

PubMed Central

Xu, Xiaomeng; Aron, Arthur; Aron, Elaine; Cao, Guikang; Feng, Tingyong; Weng, Xuchu

2011-01-01

This exploratory study examined the extent to which individual differences in sensory processing sensitivity (SPS), a temperament/personality trait characterized by social, emotional and physical sensitivity, are associated with neural response in visual areas in response to subtle changes in visual scenes. Sixteen participants completed the Highly Sensitive Person questionnaire, a standard measure of SPS. Subsequently, they were tested on a change detection task while undergoing functional magnetic resonance imaging (fMRI). SPS was associated with significantly greater activation in brain areas involved in high-order visual processing (i.e. right claustrum, left occipitotemporal, bilateral temporal and medial and posterior parietal regions) as well as in the right cerebellum, when detecting minor (vs major) changes in stimuli. These findings remained strong and significant after controlling for neuroticism and introversion, traits that are often correlated with SPS. These results provide the first evidence of neural differences associated with SPS, the first direct support for the sensory aspect of this trait that has been studied primarily for its social and affective implications, and preliminary evidence for heightened sensory processing in individuals high in SPS. PMID:20203139

Effects of visual attention on chromatic and achromatic detection sensitivities.

PubMed

Uchikawa, Keiji; Sato, Masayuki; Kuwamura, Keiko

2014-05-01

Visual attention has a significant effect on various visual functions, such as response time, detection and discrimination sensitivity, and color appearance. It has been suggested that visual attention may affect visual functions in the early visual pathways. In this study we examined selective effects of visual attention on sensitivities of the chromatic and achromatic pathways to clarify whether visual attention modifies responses in the early visual system. We used a dual task paradigm in which the observer detected a peripheral test stimulus presented at 4 deg eccentricities while the observer concurrently carried out an attention task in the central visual field. In experiment 1, it was confirmed that peripheral spectral sensitivities were reduced more for short and long wavelengths than for middle wavelengths with the central attention task so that the spectral sensitivity function changed its shape by visual attention. This indicated that visual attention affected the chromatic response more strongly than the achromatic response. In experiment 2 it was obtained that the detection thresholds increased in greater degrees in the red-green and yellow-blue chromatic directions than in the white-black achromatic direction in the dual task condition. In experiment 3 we showed that the peripheral threshold elevations depended on the combination of color-directions of the central and peripheral stimuli. Since the chromatic and achromatic responses were separately processed in the early visual pathways, the present results provided additional evidence that visual attention affects responses in the early visual pathways.

Toward unsupervised outbreak detection through visual perception of new patterns

PubMed Central

Lévy, Pierre P; Valleron, Alain-Jacques

2009-01-01

Background Statistical algorithms are routinely used to detect outbreaks of well-defined syndromes, such as influenza-like illness. These methods cannot be applied to the detection of emerging diseases for which no preexisting information is available. This paper presents a method aimed at facilitating the detection of outbreaks, when there is no a priori knowledge of the clinical presentation of cases. Methods The method uses a visual representation of the symptoms and diseases coded during a patient consultation according to the International Classification of Primary Care 2nd version (ICPC-2). The surveillance data are transformed into color-coded cells, ranging from white to red, reflecting the increasing frequency of observed signs. They are placed in a graphic reference frame mimicking body anatomy. Simple visual observation of color-change patterns over time, concerning a single code or a combination of codes, enables detection in the setting of interest. Results The method is demonstrated through retrospective analyses of two data sets: description of the patients referred to the hospital by their general practitioners (GPs) participating in the French Sentinel Network and description of patients directly consulting at a hospital emergency department (HED). Informative image color-change alert patterns emerged in both cases: the health consequences of the August 2003 heat wave were visualized with GPs' data (but passed unnoticed with conventional surveillance systems), and the flu epidemics, which are routinely detected by standard statistical techniques, were recognized visually with HED data. Conclusion Using human visual pattern-recognition capacities to detect the onset of unexpected health events implies a convenient image representation of epidemiological surveillance and well-trained "epidemiology watchers". Once these two conditions are met, one could imagine that the epidemiology watchers could signal epidemiological alerts, based on "image walls" presenting the local, regional and/or national surveillance patterns, with specialized field epidemiologists assigned to validate the signals detected. PMID:19515246

Attentional Capture of Objects Referred to by Spoken Language

ERIC Educational Resources Information Center

Salverda, Anne Pier; Altmann, Gerry T. M.

2011-01-01

Participants saw a small number of objects in a visual display and performed a visual detection or visual-discrimination task in the context of task-irrelevant spoken distractors. In each experiment, a visual cue was presented 400 ms after the onset of a spoken word. In experiments 1 and 2, the cue was an isoluminant color change and participants…

Enhanced visual performance in obsessive compulsive personality disorder.

PubMed

Ansari, Zohreh; Fadardi, Javad Salehi

2016-12-01

Visual performance is considered as commanding modality in human perception. We tested whether Obsessive-compulsive personality disorder (OCPD) people do differently in visual performance tasks than people without OCPD. One hundred ten students of Ferdowsi University of Mashhad and non-student participants were tested by Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II), among whom 18 (mean age = 29.55; SD = 5.26; 84% female) met the criteria for OCPD classification; controls were 20 persons (mean age = 27.85; SD = 5.26; female = 84%), who did not met the OCPD criteria. Both groups were tested on a modified Flicker task for two dimensions of visual performance (i.e., visual acuity: detecting the location of change, complexity, and size; and visual contrast sensitivity). The OCPD group had responded more accurately on pairs related to size, complexity, and contrast, but spent more time to detect a change on pairs related to complexity and contrast. The OCPD individuals seem to have more accurate visual performance than non-OCPD controls. The findings support the relationship between personality characteristics and visual performance within the framework of top-down processing model. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Color categories affect pre-attentive color perception.

PubMed

Clifford, Alexandra; Holmes, Amanda; Davies, Ian R L; Franklin, Anna

2010-10-01

Categorical perception (CP) of color is the faster and/or more accurate discrimination of colors from different categories than equivalently spaced colors from the same category. Here, we investigate whether color CP at early stages of chromatic processing is independent of top-down modulation from attention. A visual oddball task was employed where frequent and infrequent colored stimuli were either same- or different-category, with chromatic differences equated across conditions. Stimuli were presented peripheral to a central distractor task to elicit an event-related potential (ERP) known as the visual mismatch negativity (vMMN). The vMMN is an index of automatic and pre-attentive visual change detection arising from generating loci in visual cortices. The results revealed a greater vMMN for different-category than same-category change detection when stimuli appeared in the lower visual field, and an absence of attention-related ERP components. The findings provide the first clear evidence for an automatic and pre-attentive categorical code for color. Copyright © 2010 Elsevier B.V. All rights reserved.

Use of optical coherence tomography to evaluate visual acuity and visual field changes in dengue fever.

PubMed

Rhee, Taek Kwan; Han, Jung Il

2014-02-01

Dengue fever is a viral disease that is transmitted by mosquitoes and affects humans. In rare cases, dengue fever can cause visual impairment, which usually occurs within 1 month after contracting dengue fever and ranges from mild blurring of vision to severe blindness. Visual impairment due to dengue fever can be detected through angiography, retinography, optical coherence tomography (OCT) imaging, electroretinography, event electroencephalography (visually evoked potentials), and visual field analysis. The purpose of this study is to report changes in the eye captured using fluorescein angiography, indocyanine green, and OCT in 3 cases of dengue fever visual impairment associated with consistent visual symptoms and similar retinochoroidopathic changes. The OCT results of the three patients with dengue fever showed thinning of the outer retinal layer and disruption of the inner segment/outer segment (IS/OS) junction. While thinning of the retina outer layer is an irreversible process, disruption of IS/OS junction is reported to be reversible. Follow-up examination of individuals with dengue fever and associated visual impairment should involve the use of OCT to evaluate visual acuity and visual field changes in patients with acute choroidal ischemia.

Dissociable loss of the representations in visual short-term memory.

PubMed

Li, Jie

2016-01-01

The present study investigated in what manner the information in visual short-term memory (VSTM) is lost. Participants memorized four items, one of which was given higher priority later by a retro-cue. Then participants were required to detect a possible change, which could be either a large or small change, occurred to one of the items. The results showed that the detection performance for the small change of the uncued items was poorer than the cued item, yet large change that occurred to all four memory items could be detected perfectly, indicating that the uncued representations lost some detailed information yet still had some basic features retained in VSTM. The present study suggests that after being encoded into VSTM, the information is not lost in an object-based manner; rather, features of an item are still dissociable, so that they can be lost separately.

Remembering Complex Objects in Visual Working Memory: Do Capacity Limits Restrict Objects or Features?

PubMed Central

Hardman, Kyle; Cowan, Nelson

2014-01-01

Visual working memory stores stimuli from our environment as representations that can be accessed by high-level control processes. This study addresses a longstanding debate in the literature about whether storage limits in visual working memory include a limit to the complexity of discrete items. We examined the issue with a number of change-detection experiments that used complex stimuli which possessed multiple features per stimulus item. We manipulated the number of relevant features of the stimulus objects in order to vary feature load. In all of our experiments, we found that increased feature load led to a reduction in change-detection accuracy. However, we found that feature load alone could not account for the results, but that a consideration of the number of relevant objects was also required. This study supports capacity limits for both feature and object storage in visual working memory. PMID:25089739

Exogenous Attention Influences Visual Short-Term Memory in Infants

ERIC Educational Resources Information Center

Ross-Sheehy, Shannon; Oakes, Lisa M.; Luck, Steven J.

2011-01-01

Two experiments examined the hypothesis that developing visual attentional mechanisms influence infants' Visual Short-Term Memory (VSTM) in the context of multiple items. Five- and 10-month-old infants (N = 76) received a change detection task in which arrays of three differently colored squares appeared and disappeared. On each trial one square…

Color is processed less efficiently than orientation in change detection but more efficiently in visual search.

PubMed

Huang, Liqiang

2015-05-01

Basic visual features (e.g., color, orientation) are assumed to be processed in the same general way across different visual tasks. Here, a significant deviation from this assumption was predicted on the basis of the analysis of stimulus spatial structure, as characterized by the Boolean-map notion. If a task requires memorizing the orientations of a set of bars, then the map consisting of those bars can be readily used to hold the overall structure in memory and will thus be especially useful. If the task requires visual search for a target, then the map, which contains only an overall structure, will be of little use. Supporting these predictions, the present study demonstrated that in comparison to stimulus colors, bar orientations were processed more efficiently in change-detection tasks but less efficiently in visual search tasks (Cohen's d = 4.24). In addition to offering support for the role of the Boolean map in conscious access, the present work also throws doubts on the generality of processing visual features. © The Author(s) 2015.

Eyes Matched to the Prize: The State of Matched Filters in Insect Visual Circuits.

PubMed

Kohn, Jessica R; Heath, Sarah L; Behnia, Rudy

2018-01-01

Confronted with an ever-changing visual landscape, animals must be able to detect relevant stimuli and translate this information into behavioral output. A visual scene contains an abundance of information: to interpret the entirety of it would be uneconomical. To optimally perform this task, neural mechanisms exist to enhance the detection of important features of the sensory environment while simultaneously filtering out irrelevant information. This can be accomplished by using a circuit design that implements specific "matched filters" that are tuned to relevant stimuli. Following this rule, the well-characterized visual systems of insects have evolved to streamline feature extraction on both a structural and functional level. Here, we review examples of specialized visual microcircuits for vital behaviors across insect species, including feature detection, escape, and estimation of self-motion. Additionally, we discuss how these microcircuits are modulated to weigh relevant input with respect to different internal and behavioral states.

A matter of time: improvement of visual temporal processing during training-induced restoration of light detection performance

PubMed Central

Poggel, Dorothe A.; Treutwein, Bernhard; Sabel, Bernhard A.; Strasburger, Hans

2015-01-01

The issue of how basic sensory and temporal processing are related is still unresolved. We studied temporal processing, as assessed by simple visual reaction times (RT) and double-pulse resolution (DPR), in patients with partial vision loss after visual pathway lesions and investigated whether vision restoration training (VRT), a training program designed to improve light detection performance, would also affect temporal processing. Perimetric and campimetric visual field tests as well as maps of DPR thresholds and RT were acquired before and after a 3 months training period with VRT. Patient performance was compared to that of age-matched healthy subjects. Intact visual field size increased during training. Averaged across the entire visual field, DPR remained constant while RT improved slightly. However, in transition zones between the blind and intact areas (areas of residual vision) where patients had shown between 20 and 80% of stimulus detection probability in pre-training visual field tests, both DPR and RT improved markedly. The magnitude of improvement depended on the defect depth (or degree of intactness) of the respective region at baseline. Inter-individual training outcome variability was very high, with some patients showing little change and others showing performance approaching that of healthy controls. Training-induced improvement of light detection in patients with visual field loss thus generalized to dynamic visual functions. The findings suggest that similar neural mechanisms may underlie the impairment and subsequent training-induced functional recovery of both light detection and temporal processing. PMID:25717307

Augmenting Amyloid PET Interpretations With Quantitative Information Improves Consistency of Early Amyloid Detection.

PubMed

Harn, Nicholas R; Hunt, Suzanne L; Hill, Jacqueline; Vidoni, Eric; Perry, Mark; Burns, Jeffrey M

2017-08-01

Establishing reliable methods for interpreting elevated cerebral amyloid-β plaque on PET scans is increasingly important for radiologists, as availability of PET imaging in clinical practice increases. We examined a 3-step method to detect plaque in cognitively normal older adults, focusing on the additive value of quantitative information during the PET scan interpretation process. Fifty-five F-florbetapir PET scans were evaluated by 3 experienced raters. Scans were first visually interpreted as having "elevated" or "nonelevated" plaque burden ("Visual Read"). Images were then processed using a standardized quantitative analysis software (MIMneuro) to generate whole brain and region of interest SUV ratios. This "Quantitative Read" was considered elevated if at least 2 of 6 regions of interest had an SUV ratio of more than 1.1. The final interpretation combined both visual and quantitative data together ("VisQ Read"). Cohen kappa values were assessed as a measure of interpretation agreement. Plaque was elevated in 25.5% to 29.1% of the 165 total Visual Reads. Interrater agreement was strong (kappa = 0.73-0.82) and consistent with reported values. Quantitative Reads were elevated in 45.5% of participants. Final VisQ Reads changed from initial Visual Reads in 16 interpretations (9.7%), with most changing from "nonelevated" Visual Reads to "elevated." These changed interpretations demonstrated lower plaque quantification than those initially read as "elevated" that remained unchanged. Interrater variability improved for VisQ Reads with the addition of quantitative information (kappa = 0.88-0.96). Inclusion of quantitative information increases consistency of PET scan interpretations for early detection of cerebral amyloid-β plaque accumulation.

The role of convexity in perception of symmetry and in visual short-term memory.

PubMed

Bertamini, Marco; Helmy, Mai Salah; Hulleman, Johan

2013-01-01

Visual perception of shape is affected by coding of local convexities and concavities. For instance, a recent study reported that deviations from symmetry carried by convexities were easier to detect than deviations carried by concavities. We removed some confounds and extended this work from a detection of reflection of a contour (i.e., bilateral symmetry), to a detection of repetition of a contour (i.e., translational symmetry). We tested whether any convexity advantage is specific to bilateral symmetry in a two-interval (Experiment 1) and a single-interval (Experiment 2) detection task. In both, we found a convexity advantage only for repetition. When we removed the need to choose which region of the contour to monitor (Experiment 3) the effect disappeared. In a second series of studies, we again used shapes with multiple convex or concave features. Participants performed a change detection task in which only one of the features could change. We did not find any evidence that convexities are special in visual short-term memory, when the to-be-remembered features only changed shape (Experiment 4), when they changed shape and changed from concave to convex and vice versa (Experiment 5), or when these conditions were mixed (Experiment 6). We did find a small advantage for coding convexity as well as concavity over an isolated (and thus ambiguous) contour. The latter is consistent with the known effect of closure on processing of shape. We conclude that convexity plays a role in many perceptual tasks but that it does not have a basic encoding advantage over concavity.

Colorimetric Detection Of Substances In Liquids And Gases

NASA Technical Reports Server (NTRS)

Harris, J. Milton; Mcgill, R. Andrew; Paley, Mark S.

1992-01-01

Thin polymer films containing solvatochromic dyes used as sensing elements to detect substances dissolved in liquids and gases. Dyes do not react with liquids in which dissolved, but do respond to changes in chemical compositions by changing color. Concentration determined visually by comparison of color with predetermined standard chart, or spectrophotometrically.

Visual Analysis for Detection and Quantification of Pseudomonas cichorii Disease Severity in Tomato Plants.

PubMed

Rajendran, Dhinesh Kumar; Park, Eunsoo; Nagendran, Rajalingam; Hung, Nguyen Bao; Cho, Byoung-Kwan; Kim, Kyung-Hwan; Lee, Yong Hoon

2016-08-01

Pathogen infection in plants induces complex responses ranging from gene expression to metabolic processes in infected plants. In spite of many studies on biotic stress-related changes in host plants, little is known about the metabolic and phenotypic responses of the host plants to Pseudomonas cichorii infection based on image-based analysis. To investigate alterations in tomato plants according to disease severity, we inoculated plants with different cell densities of P. cichorii using dipping and syringe infiltration methods. High-dose inocula (≥ 10(6) cfu/ml) induced evident necrotic lesions within one day that corresponded to bacterial growth in the infected tissues. Among the chlorophyll fluorescence parameters analyzed, changes in quantum yield of PSII (ΦPSII) and non-photochemical quenching (NPQ) preceded the appearance of visible symptoms, but maximum quantum efficiency of PSII (Fv/Fm) was altered well after symptom development. Visible/near infrared and chlorophyll fluorescence hyperspectral images detected changes before symptom appearance at low-density inoculation. The results of this study indicate that the P. cichorii infection severity can be detected by chlorophyll fluorescence assay and hyperspectral images prior to the onset of visible symptoms, indicating the feasibility of early detection of diseases. However, to detect disease development by hyperspectral imaging, more detailed protocols and analyses are necessary. Taken together, change in chlorophyll fluorescence is a good parameter for early detection of P. cichorii infection in tomato plants. In addition, image-based visualization of infection severity before visual damage appearance will contribute to effective management of plant diseases.

Iconic memory requires attention

PubMed Central

Persuh, Marjan; Genzer, Boris; Melara, Robert D.

2012-01-01

Two experiments investigated whether attention plays a role in iconic memory, employing either a change detection paradigm (Experiment 1) or a partial-report paradigm (Experiment 2). In each experiment, attention was taxed during initial display presentation, focusing the manipulation on consolidation of information into iconic memory, prior to transfer into working memory. Observers were able to maintain high levels of performance (accuracy of change detection or categorization) even when concurrently performing an easy visual search task (low load). However, when the concurrent search was made difficult (high load), observers' performance dropped to almost chance levels, while search accuracy held at single-task levels. The effects of attentional load remained the same across paradigms. The results suggest that, without attention, participants consolidate in iconic memory only gross representations of the visual scene, information too impoverished for successful detection of perceptual change or categorization of features. PMID:22586389

Iconic memory requires attention.

PubMed

Persuh, Marjan; Genzer, Boris; Melara, Robert D

2012-01-01

Two experiments investigated whether attention plays a role in iconic memory, employing either a change detection paradigm (Experiment 1) or a partial-report paradigm (Experiment 2). In each experiment, attention was taxed during initial display presentation, focusing the manipulation on consolidation of information into iconic memory, prior to transfer into working memory. Observers were able to maintain high levels of performance (accuracy of change detection or categorization) even when concurrently performing an easy visual search task (low load). However, when the concurrent search was made difficult (high load), observers' performance dropped to almost chance levels, while search accuracy held at single-task levels. The effects of attentional load remained the same across paradigms. The results suggest that, without attention, participants consolidate in iconic memory only gross representations of the visual scene, information too impoverished for successful detection of perceptual change or categorization of features.

Spatial Probability Dynamically Modulates Visual Target Detection in Chickens

PubMed Central

Sridharan, Devarajan; Ramamurthy, Deepa L.; Knudsen, Eric I.

2013-01-01

The natural world contains a rich and ever-changing landscape of sensory information. To survive, an organism must be able to flexibly and rapidly locate the most relevant sources of information at any time. Humans and non-human primates exploit regularities in the spatial distribution of relevant stimuli (targets) to improve detection at locations of high target probability. Is the ability to flexibly modify behavior based on visual experience unique to primates? Chickens (Gallus domesticus) were trained on a multiple alternative Go/NoGo task to detect a small, briefly-flashed dot (target) in each of the quadrants of the visual field. When targets were presented with equal probability (25%) in each quadrant, chickens exhibited a distinct advantage for detecting targets at lower, relative to upper, hemifield locations. Increasing the probability of presentation in the upper hemifield locations (to 80%) dramatically improved detection performance at these locations to be on par with lower hemifield performance. Finally, detection performance in the upper hemifield changed on a rapid timescale, improving with successive target detections, and declining with successive detections at the diagonally opposite location in the lower hemifield. These data indicate the action of a process that in chickens, as in primates, flexibly and dynamically modulates detection performance based on the spatial probabilities of sensory stimuli as well as on recent performance history. PMID:23734188

Perceptual learning increases the strength of the earliest signals in visual cortex.

PubMed

Bao, Min; Yang, Lin; Rios, Cristina; He, Bin; Engel, Stephen A

2010-11-10

Training improves performance on most visual tasks. Such perceptual learning can modify how information is read out from, and represented in, later visual areas, but effects on early visual cortex are controversial. In particular, it remains unknown whether learning can reshape neural response properties in early visual areas independent from feedback arising in later cortical areas. Here, we tested whether learning can modify feedforward signals in early visual cortex as measured by the human electroencephalogram. Fourteen subjects were trained for >24 d to detect a diagonal grating pattern in one quadrant of the visual field. Training improved performance, reducing the contrast needed for reliable detection, and also reliably increased the amplitude of the earliest component of the visual evoked potential, the C1. Control orientations and locations showed smaller effects of training. Because the C1 arises rapidly and has a source in early visual cortex, our results suggest that learning can increase early visual area response through local receptive field changes without feedback from later areas.

Detection of emetic activity in the cat by monitoring venous pressure and audio signals

NASA Technical Reports Server (NTRS)

Nagahara, A.; Fox, Robert A.; Daunton, Nancy G.; Elfar, S.

1991-01-01

To investigate the use of audio signals as a simple, noninvasive measure of emetic activity, the relationship between the somatic events and sounds associated with retching and vomiting was studied. Thoracic venous pressure obtained from an implanted external jugular catheter was shown to provide a precise measure of the somatic events associated with retching and vomiting. Changes in thoracic venous pressure monitored through an indwelling external jugular catheter with audio signals, obtained from a microphone located above the animal in a test chamber, were compared. In addition, two independent observers visually monitored emetic episodes. Retching and vomiting were induced by injection of xylazine (0.66mg/kg s.c.), or by motion. A unique audio signal at a frequency of approximately 250 Hz is produced at the time of the negative thoracic venous pressure change associated with retching. Sounds with higher frequencies (around 2500 Hz) occur in conjunction with the positive pressure changes associated with vomiting. These specific signals could be discriminated reliably by individuals reviewing the audio recordings of the sessions. Retching and those emetic episodes associated with positive venous pressure changes were detected accurately by audio monitoring, with 90 percent of retches and 100 percent of emetic episodes correctly identified. Retching was detected more accurately (p is less than .05) by audio monitoring than by direct visual observation. However, with visual observation a few incidents in which stomach contents were expelled in the absence of positive pressure changes or detectable sounds were identified. These data suggest that in emetic situations, the expulsion of stomach contents may be accomplished by more than one neuromuscular system and that audio signals can be used to detect emetic episodes associated with thoracic venous pressure changes.

Changes in Visual/Spatial and Analytic Strategy Use in Organic Chemistry with the Development of Expertise

ERIC Educational Resources Information Center

Vlacholia, Maria; Vosniadou, Stella; Roussos, Petros; Salta, Katerina; Kazi, Smaragda; Sigalas, Michael; Tzougraki, Chryssa

2017-01-01

We present two studies that investigated the adoption of visual/spatial and analytic strategies by individuals at different levels of expertise in the area of organic chemistry, using the Visual Analytic Chemistry Task (VACT). The VACT allows the direct detection of analytic strategy use without drawing inferences about underlying mental…

[Visual representation of natural scenes in flicker changes].

PubMed

Nakashima, Ryoichi; Yokosawa, Kazuhiko

2010-08-01

Coherence theory in scene perception (Rensink, 2002) assumes the retention of volatile object representations on which attention is not focused. On the other hand, visual memory theory in scene perception (Hollingworth & Henderson, 2002) assumes that robust object representations are retained. In this study, we hypothesized that the difference between these two theories is derived from the difference of the experimental tasks that they are based on. In order to verify this hypothesis, we examined the properties of visual representation by using a change detection and memory task in a flicker paradigm. We measured the representations when participants were instructed to search for a change in a scene, and compared them with the intentional memory representations. The visual representations were retained in visual long-term memory even in the flicker paradigm, and were as robust as the intentional memory representations. However, the results indicate that the representations are unavailable for explicitly localizing a scene change, but are available for answering the recognition test. This suggests that coherence theory and visual memory theory are compatible.

The role of visual attention in predicting driving impairment in older adults.

PubMed

Hoffman, Lesa; McDowd, Joan M; Atchley, Paul; Dubinsky, Richard

2005-12-01

This study evaluated the role of visual attention (as measured by the DriverScan change detection task and the Useful Field of View Test [UFOV]) in the prediction of driving impairment in 155 adults between the ages of 63 and 87. In contrast to previous research, participants were not oversampled for visual impairment or history of automobile accidents. Although a history of automobile accidents within the past 3 years could not be predicted using any variable, driving performance in a low-fidelity simulator could be significantly predicted by performance in the change detection task and by the divided and selection attention subtests of the UFOV in structural equation models. The sensitivity and specificity of each measure in identifying at-risk drivers were also evaluated with receiver operating characteristic curves.

Color-Change Detection Activity in the Primate Superior Colliculus.

PubMed

Herman, James P; Krauzlis, Richard J

2017-01-01

The primate superior colliculus (SC) is a midbrain structure that participates in the control of spatial attention. Previous studies examining the role of the SC in attention have mostly used luminance-based visual features (e.g., motion, contrast) as the stimuli and saccadic eye movements as the behavioral response, both of which are known to modulate the activity of SC neurons. To explore the limits of the SC's involvement in the control of spatial attention, we recorded SC neuronal activity during a task using color, a visual feature dimension not traditionally associated with the SC, and required monkeys to detect threshold-level changes in the saturation of a cued stimulus by releasing a joystick during maintained fixation. Using this color-based spatial attention task, we found substantial cue-related modulation in all categories of visually responsive neurons in the intermediate layers of the SC. Notably, near-threshold changes in color saturation, both increases and decreases, evoked phasic bursts of activity with magnitudes as large as those evoked by stimulus onset. This change-detection activity had two distinctive features: activity for hits was larger than for misses, and the timing of change-detection activity accounted for 67% of joystick release latency, even though it preceded the release by at least 200 ms. We conclude that during attention tasks, SC activity denotes the behavioral relevance of the stimulus regardless of feature dimension and that phasic event-related SC activity is suitable to guide the selection of manual responses as well as saccadic eye movements.

Making the invisible visible: verbal but not visual cues enhance visual detection.

PubMed

Lupyan, Gary; Spivey, Michael J

2010-07-07

Can hearing a word change what one sees? Although visual sensitivity is known to be enhanced by attending to the location of the target, perceptual enhancements of following cues to the identity of an object have been difficult to find. Here, we show that perceptual sensitivity is enhanced by verbal, but not visual cues. Participants completed an object detection task in which they made an object-presence or -absence decision to briefly-presented letters. Hearing the letter name prior to the detection task increased perceptual sensitivity (d'). A visual cue in the form of a preview of the to-be-detected letter did not. Follow-up experiments found that the auditory cuing effect was specific to validly cued stimuli. The magnitude of the cuing effect positively correlated with an individual measure of vividness of mental imagery; introducing uncertainty into the position of the stimulus did not reduce the magnitude of the cuing effect, but eliminated the correlation with mental imagery. Hearing a word made otherwise invisible objects visible. Interestingly, seeing a preview of the target stimulus did not similarly enhance detection of the target. These results are compatible with an account in which auditory verbal labels modulate lower-level visual processing. The findings show that a verbal cue in the form of hearing a word can influence even the most elementary visual processing and inform our understanding of how language affects perception.

Direction of Auditory Pitch-Change Influences Visual Search for Slope From Graphs.

PubMed

Parrott, Stacey; Guzman-Martinez, Emmanuel; Orte, Laura; Grabowecky, Marcia; Huntington, Mark D; Suzuki, Satoru

2015-01-01

Linear trend (slope) is important information conveyed by graphs. We investigated how sounds influenced slope detection in a visual search paradigm. Four bar graphs or scatter plots were presented on each trial. Participants looked for a positive-slope or a negative-slope target (in blocked trials), and responded to targets in a go or no-go fashion. For example, in a positive-slope-target block, the target graph displayed a positive slope while other graphs displayed negative slopes (a go trial), or all graphs displayed negative slopes (a no-go trial). When an ascending or descending sound was presented concurrently, ascending sounds slowed detection of negative-slope targets whereas descending sounds slowed detection of positive-slope targets. The sounds had no effect when they immediately preceded the visual search displays, suggesting that the results were due to crossmodal interaction rather than priming. The sounds also had no effect when targets were words describing slopes, such as "positive," "negative," "increasing," or "decreasing," suggesting that the results were unlikely due to semantic-level interactions. Manipulations of spatiotemporal similarity between sounds and graphs had little effect. These results suggest that ascending and descending sounds influence visual search for slope based on a general association between the direction of auditory pitch-change and visual linear trend.

Peptide-activated gold nanoparticles for selective visual sensing of virus

NASA Astrophysics Data System (ADS)

Sajjanar, Basavaraj; Kakodia, Bhuvna; Bisht, Deepika; Saxena, Shikha; Singh, Arvind Kumar; Joshi, Vinay; Tiwari, Ashok Kumar; Kumar, Satish

2015-05-01

In this study, we report peptide-gold nanoparticles (AuNP)-based visual sensor for viruses. Citrate-stabilized AuNP (20 ± 1.9 nm) were functionalized with strong sulfur-gold interface using cysteinylated virus-specific peptide. Peptide-Cys-AuNP formed complexes with the viruses which made them to aggregate. The aggregation can be observed with naked eye and also with UV-Vis spectrophotometer as a color change from bright red to purple. The test allows for fast and selective detection of specific viruses. Spectroscopic measurements showed high linear correlation ( R 2 = 0.995) between the changes in optical density ratio (OD610/OD520) with the different concentrations of virus. The new method was compared with the hemagglutinating (HA) test for Newcastle disease virus (NDV). The results indicated that peptide-Cys-AuNP was more sensitive and can visually detect minimum number of virus particles present in the biological samples. The limit of detection for the NDV was 0.125 HA units of the virus. The method allows for selective detection and quantification of the NDV, and requires no isolation of viral RNA and PCR experiments. This strategy may be utilized for detection of other important human and animal viral pathogens.

Conscious visual memory with minimal attention.

PubMed

Pinto, Yair; Vandenbroucke, Annelinde R; Otten, Marte; Sligte, Ilja G; Seth, Anil K; Lamme, Victor A F

2017-02-01

Is conscious visual perception limited to the locations that a person attends? The remarkable phenomenon of change blindness, which shows that people miss nearly all unattended changes in a visual scene, suggests the answer is yes. However, change blindness is found after visual interference (a mask or a new scene), so that subjects have to rely on working memory (WM), which has limited capacity, to detect the change. Before such interference, however, a much larger capacity store, called fragile memory (FM), which is easily overwritten by newly presented visual information, is present. Whether these different stores depend equally on spatial attention is central to the debate on the role of attention in conscious vision. In 2 experiments, we found that minimizing spatial attention almost entirely erases visual WM, as expected. Critically, FM remains largely intact. Moreover, minimally attended FM responses yield accurate metacognition, suggesting that conscious memory persists with limited spatial attention. Together, our findings help resolve the fundamental issue of how attention affects perception: Both visual consciousness and memory can be supported by only minimal attention. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

An introduction to DARC technology.

PubMed

Ahmad, Syed Shoeb

2017-01-01

Glaucoma is a multi-factorial neurodegenerative disorder. The common denominator in all types of glaucomas is retinal ganglion cell death through apoptosis. However, this cellular demise in glaucoma is detected late by structural or functional analyses. There can be a 10-year delay prior to the appearance of visual field defects and pre-perimetric glaucoma is an issue still being addressed. However, a new cutting-edge technology called detection of apoptosing retinal cells (DARC) is being developed. This technique is capable of non-invasive, real-time visualization of apoptotic changes at the cellular level. It can detect glaucomatous cell damage at a very early stage, at the moment apoptosis starts, and thus management can be initiated even prior to development of visual field changes. In future, this technique will also be able to provide conclusive evidence of the effectiveness of treatment protocol and the need for any modifications which may be required. This article aims to provide a concise review of DARC technology.

An efficient probe for rapid detection of cyanide in water at parts per billion levels and naked-eye detection of endogenous cyanide.

PubMed

Kumari, Namita; Jha, Satadru; Bhattacharya, Santanu

2014-03-01

A new molecular probe based on an oxidized bis-indolyl skeleton has been developed for rapid and sensitive visual detection of cyanide ions in water and also for the detection of endogenously bound cyanide. The probe allows the "naked-eye" detection of cyanide ions in water with a visual color change from red to yellow (Δλmax =80 nm) with the immediate addition of the probe. It shows high selectivity towards the cyanide ion without any interference from other anions. The detection of cyanide by the probe is ratiometric, thus making the detection quantitative. A Michael-type addition reaction of the probe with the cyanide ion takes place during this chemodosimetric process. In water, the detection limit was found to be at the parts per million level, which improved drastically when a neutral micellar medium was employed, and it showed a parts-per-billion-level detection, which is even 25-fold lower than the permitted limits of cyanide in water. The probe could also efficiently detect the endogenously bound cyanide in cassava (a staple food) with a clear visual color change without requiring any sample pretreatment and/or any special reaction conditions such as pH or temperature. Thus the probe could serve as a practical naked-eye probe for "in-field" experiments without requiring any sophisticated instruments. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Audio-Visual Integration in a Redundant Target Paradigm: A Comparison between Rhesus Macaque and Man

PubMed Central

Bremen, Peter; Massoudi, Rooholla; Van Wanrooij, Marc M.; Van Opstal, A. J.

2017-01-01

The mechanisms underlying multi-sensory interactions are still poorly understood despite considerable progress made since the first neurophysiological recordings of multi-sensory neurons. While the majority of single-cell neurophysiology has been performed in anesthetized or passive-awake laboratory animals, the vast majority of behavioral data stems from studies with human subjects. Interpretation of neurophysiological data implicitly assumes that laboratory animals exhibit perceptual phenomena comparable or identical to those observed in human subjects. To explicitly test this underlying assumption, we here characterized how two rhesus macaques and four humans detect changes in intensity of auditory, visual, and audio-visual stimuli. These intensity changes consisted of a gradual envelope modulation for the sound, and a luminance step for the LED. Subjects had to detect any perceived intensity change as fast as possible. By comparing the monkeys' results with those obtained from the human subjects we found that (1) unimodal reaction times differed across modality, acoustic modulation frequency, and species, (2) the largest facilitation of reaction times with the audio-visual stimuli was observed when stimulus onset asynchronies were such that the unimodal reactions would occur at the same time (response, rather than physical synchrony), and (3) the largest audio-visual reaction-time facilitation was observed when unimodal auditory stimuli were difficult to detect, i.e., at slow unimodal reaction times. We conclude that despite marked unimodal heterogeneity, similar multisensory rules applied to both species. Single-cell neurophysiology in the rhesus macaque may therefore yield valuable insights into the mechanisms governing audio-visual integration that may be informative of the processes taking place in the human brain. PMID:29238295

Audio-Visual Integration in a Redundant Target Paradigm: A Comparison between Rhesus Macaque and Man.

PubMed

Bremen, Peter; Massoudi, Rooholla; Van Wanrooij, Marc M; Van Opstal, A J

2017-01-01

The mechanisms underlying multi-sensory interactions are still poorly understood despite considerable progress made since the first neurophysiological recordings of multi-sensory neurons. While the majority of single-cell neurophysiology has been performed in anesthetized or passive-awake laboratory animals, the vast majority of behavioral data stems from studies with human subjects. Interpretation of neurophysiological data implicitly assumes that laboratory animals exhibit perceptual phenomena comparable or identical to those observed in human subjects. To explicitly test this underlying assumption, we here characterized how two rhesus macaques and four humans detect changes in intensity of auditory, visual, and audio-visual stimuli. These intensity changes consisted of a gradual envelope modulation for the sound, and a luminance step for the LED. Subjects had to detect any perceived intensity change as fast as possible. By comparing the monkeys' results with those obtained from the human subjects we found that (1) unimodal reaction times differed across modality, acoustic modulation frequency, and species, (2) the largest facilitation of reaction times with the audio-visual stimuli was observed when stimulus onset asynchronies were such that the unimodal reactions would occur at the same time (response, rather than physical synchrony), and (3) the largest audio-visual reaction-time facilitation was observed when unimodal auditory stimuli were difficult to detect, i.e., at slow unimodal reaction times. We conclude that despite marked unimodal heterogeneity, similar multisensory rules applied to both species. Single-cell neurophysiology in the rhesus macaque may therefore yield valuable insights into the mechanisms governing audio-visual integration that may be informative of the processes taking place in the human brain.

The development of real-time stability supports visual working memory performance: Young children's feature binding can be improved through perceptual structure.

PubMed

Simmering, Vanessa R; Wood, Chelsey M

2017-08-01

Working memory is a basic cognitive process that predicts higher-level skills. A central question in theories of working memory development is the generality of the mechanisms proposed to explain improvements in performance. Prior theories have been closely tied to particular tasks and/or age groups, limiting their generalizability. The cognitive dynamics theory of visual working memory development has been proposed to overcome this limitation. From this perspective, developmental improvements arise through the coordination of cognitive processes to meet demands of different behavioral tasks. This notion is described as real-time stability, and can be probed through experiments that assess how changing task demands impact children's performance. The current studies test this account by probing visual working memory for colors and shapes in a change detection task that compares detection of changes to new features versus swaps in color-shape binding. In Experiment 1, 3- to 4-year-old children showed impairments specific to binding swaps, as predicted by decreased real-time stability early in development; 5- to 6-year-old children showed a slight advantage on binding swaps, but 7- to 8-year-old children and adults showed no difference across trial types. Experiment 2 tested the proposed explanation of young children's binding impairment through added perceptual structure, which supported the stability and precision of feature localization in memory-a process key to detecting binding swaps. This additional structure improved young children's binding swap detection, but not new-feature detection or adults' performance. These results provide further evidence for the cognitive dynamics and real-time stability explanation of visual working memory development. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Literature and Product Review of Visual Analytics for Maritime Awareness

DTIC Science & Technology

2009-10-28

the user’s knowledge and experience. • Riveiro et al [107] provide a useful discussion of the cognitive process of anomaly detection based on...changes over time can be seen visually. • Wilkinson et al [140] suggests that we need visual analytics for three principal purposes: checking raw data...Predictions within the Current Plot • Yue et al [146] describe an AI blackboard-based agent that leverages interactive visualization and mixed

Event-Related Potentials Elicited by Pre-Attentive Emotional Changes in Temporal Context

PubMed Central

Fujimura, Tomomi; Okanoya, Kazuo

2013-01-01

The ability to detect emotional change in the environment is essential for adaptive behavior. The current study investigated whether event-related potentials (ERPs) can reflect emotional change in a visual sequence. To assess pre-attentive processing, we examined visual mismatch negativity (vMMN): the negative potentials elicited by a deviant (infrequent) stimulus embedded in a sequence of standard (frequent) stimuli. Participants in two experiments pre-attentively viewed visual sequences of Japanese kanji with different emotional connotations while ERPs were recorded. The visual sequence in Experiment 1 consisted of neutral standards and two types of emotional deviants with a strong and weak intensity. Although the results indicated that strongly emotional deviants elicited more occipital negativity than neutral standards, it was unclear whether these negativities were derived from emotional deviation in the sequence or from the emotional significance of the deviants themselves. In Experiment 2, the two identical emotional deviants were presented against different emotional standards. One type of deviants was emotionally incongruent with the standard and the other type of deviants was emotionally congruent with the standard. The results indicated that occipital negativities elicited by deviants resulted from perceptual changes in a visual sequence at a latency of 100–200 ms and from emotional changes at latencies of 200–260 ms. Contrary to the results of the ERP experiment, reaction times to deviants showed no effect of emotional context; negative stimuli were consistently detected more rapidly than were positive stimuli. Taken together, the results suggest that brain signals can reflect emotional change in a temporal context. PMID:23671693

Event-related potentials elicited by pre-attentive emotional changes in temporal context.

PubMed

Fujimura, Tomomi; Okanoya, Kazuo

2013-01-01

The ability to detect emotional change in the environment is essential for adaptive behavior. The current study investigated whether event-related potentials (ERPs) can reflect emotional change in a visual sequence. To assess pre-attentive processing, we examined visual mismatch negativity (vMMN): the negative potentials elicited by a deviant (infrequent) stimulus embedded in a sequence of standard (frequent) stimuli. Participants in two experiments pre-attentively viewed visual sequences of Japanese kanji with different emotional connotations while ERPs were recorded. The visual sequence in Experiment 1 consisted of neutral standards and two types of emotional deviants with a strong and weak intensity. Although the results indicated that strongly emotional deviants elicited more occipital negativity than neutral standards, it was unclear whether these negativities were derived from emotional deviation in the sequence or from the emotional significance of the deviants themselves. In Experiment 2, the two identical emotional deviants were presented against different emotional standards. One type of deviants was emotionally incongruent with the standard and the other type of deviants was emotionally congruent with the standard. The results indicated that occipital negativities elicited by deviants resulted from perceptual changes in a visual sequence at a latency of 100-200 ms and from emotional changes at latencies of 200-260 ms. Contrary to the results of the ERP experiment, reaction times to deviants showed no effect of emotional context; negative stimuli were consistently detected more rapidly than were positive stimuli. Taken together, the results suggest that brain signals can reflect emotional change in a temporal context.

Dimension-based attention in visual short-term memory.

PubMed

Pilling, Michael; Barrett, Doug J K

2016-07-01

We investigated how dimension-based attention influences visual short-term memory (VSTM). This was done through examining the effects of cueing a feature dimension in two perceptual comparison tasks (change detection and sameness detection). In both tasks, a memory array and a test array consisting of a number of colored shapes were presented successively, interleaved by a blank interstimulus interval (ISI). In Experiment 1 (change detection), the critical event was a feature change in one item across the memory and test arrays. In Experiment 2 (sameness detection), the critical event was the absence of a feature change in one item across the two arrays. Auditory cues indicated the feature dimension (color or shape) of the critical event with 80 % validity; the cues were presented either prior to the memory array, during the ISI, or simultaneously with the test array. In Experiment 1, the cue validity influenced sensitivity only when the cue was given at the earliest position; in Experiment 2, the cue validity influenced sensitivity at all three cue positions. We attributed the greater effectiveness of top-down guidance by cues in the sameness detection task to the more active nature of the comparison process required to detect sameness events (Hyun, Woodman, Vogel, Hollingworth, & Luck, Journal of Experimental Psychology: Human Perception and Performance, 35; 1140-1160, 2009).

Remembering complex objects in visual working memory: do capacity limits restrict objects or features?

PubMed

Hardman, Kyle O; Cowan, Nelson

2015-03-01

Visual working memory stores stimuli from our environment as representations that can be accessed by high-level control processes. This study addresses a longstanding debate in the literature about whether storage limits in visual working memory include a limit to the complexity of discrete items. We examined the issue with a number of change-detection experiments that used complex stimuli that possessed multiple features per stimulus item. We manipulated the number of relevant features of the stimulus objects in order to vary feature load. In all of our experiments, we found that increased feature load led to a reduction in change-detection accuracy. However, we found that feature load alone could not account for the results but that a consideration of the number of relevant objects was also required. This study supports capacity limits for both feature and object storage in visual working memory. PsycINFO Database Record (c) 2015 APA, all rights reserved.

[Eyeball structure changes in high myopic patients and their significance for forensic assessment].

PubMed

Liu, Yi-Chang; Xia, Wen-Tao; Zhou, Xing-Tao; Liu, Rui-Jue; Bian, Shi-Zhong; Ying, Chong-Liang; Zhu, Guang-You

2008-10-01

There are irreversible eyeball structural changes in high myopic patients. These changes include axial length, corneal radius, anterior chamber depth, fundus degeneration, macula thickness, etc. There is a close relationship between the damage degree of visual function and these changes. The incidence of complications, such as vitreous opacity, posterior vitreous detachment, cataract, glaucoma, posterior staphyloma and retina detachment, is also highly related to the myopia diopter. More and more researches have indicated that the myopia diopter and the level of visual function are affected by multiple factors. It is promising to detect all of these changes by different kinds of methods, and to assess visual function through these changes. By clarifying these changes, it is also useful to distinguish traumatic damage from disease to provide evidence for forensic assessment of eye injuries.

The effects of stereo disparity on the behavioural and electrophysiological correlates of perception of audio-visual motion in depth.

PubMed

Harrison, Neil R; Witheridge, Sian; Makin, Alexis; Wuerger, Sophie M; Pegna, Alan J; Meyer, Georg F

2015-11-01

Motion is represented by low-level signals, such as size-expansion in vision or loudness changes in the auditory modality. The visual and auditory signals from the same object or event may be integrated and facilitate detection. We explored behavioural and electrophysiological correlates of congruent and incongruent audio-visual depth motion in conditions where auditory level changes, visual expansion, and visual disparity cues were manipulated. In Experiment 1 participants discriminated auditory motion direction whilst viewing looming or receding, 2D or 3D, visual stimuli. Responses were faster and more accurate for congruent than for incongruent audio-visual cues, and the congruency effect (i.e., difference between incongruent and congruent conditions) was larger for visual 3D cues compared to 2D cues. In Experiment 2, event-related potentials (ERPs) were collected during presentation of the 2D and 3D, looming and receding, audio-visual stimuli, while participants detected an infrequent deviant sound. Our main finding was that audio-visual congruity was affected by retinal disparity at an early processing stage (135-160ms) over occipito-parietal scalp. Topographic analyses suggested that similar brain networks were activated for the 2D and 3D congruity effects, but that cortical responses were stronger in the 3D condition. Differences between congruent and incongruent conditions were observed between 140-200ms, 220-280ms, and 350-500ms after stimulus onset. Copyright © 2015 Elsevier Ltd. All rights reserved.

Recent advances in targeted endoscopic imaging: Early detection of gastrointestinal neoplasms

PubMed Central

Kwon, Yong-Soo; Cho, Young-Seok; Yoon, Tae-Jong; Kim, Ho-Shik; Choi, Myung-Gyu

2012-01-01

Molecular imaging has emerged as a new discipline in gastrointestinal endoscopy. This technology encompasses modalities that can visualize disease-specific morphological or functional tissue changes based on the molecular signature of individual cells. Molecular imaging has several advantages including minimal damage to tissues, repetitive visualization, and utility for conducting quantitative analyses. Advancements in basic science coupled with endoscopy have made early detection of gastrointestinal cancer possible. Molecular imaging during gastrointestinal endoscopy requires the development of safe biomarkers and exogenous probes to detect molecular changes in cells with high specificity anda high signal-to-background ratio. Additionally, a high-resolution endoscope with an accurate wide-field viewing capability must be developed. Targeted endoscopic imaging is expected to improve early diagnosis and individual therapy of gastrointestinal cancer. PMID:22442742

Making the Invisible Visible: Verbal but Not Visual Cues Enhance Visual Detection

PubMed Central

Lupyan, Gary; Spivey, Michael J.

2010-01-01

Background Can hearing a word change what one sees? Although visual sensitivity is known to be enhanced by attending to the location of the target, perceptual enhancements of following cues to the identity of an object have been difficult to find. Here, we show that perceptual sensitivity is enhanced by verbal, but not visual cues. Methodology/Principal Findings Participants completed an object detection task in which they made an object-presence or -absence decision to briefly-presented letters. Hearing the letter name prior to the detection task increased perceptual sensitivity (d′). A visual cue in the form of a preview of the to-be-detected letter did not. Follow-up experiments found that the auditory cuing effect was specific to validly cued stimuli. The magnitude of the cuing effect positively correlated with an individual measure of vividness of mental imagery; introducing uncertainty into the position of the stimulus did not reduce the magnitude of the cuing effect, but eliminated the correlation with mental imagery. Conclusions/Significance Hearing a word made otherwise invisible objects visible. Interestingly, seeing a preview of the target stimulus did not similarly enhance detection of the target. These results are compatible with an account in which auditory verbal labels modulate lower-level visual processing. The findings show that a verbal cue in the form of hearing a word can influence even the most elementary visual processing and inform our understanding of how language affects perception. PMID:20628646

Boosting pitch encoding with audiovisual interactions in congenital amusia.

PubMed

Albouy, Philippe; Lévêque, Yohana; Hyde, Krista L; Bouchet, Patrick; Tillmann, Barbara; Caclin, Anne

2015-01-01

The combination of information across senses can enhance perception, as revealed for example by decreased reaction times or improved stimulus detection. Interestingly, these facilitatory effects have been shown to be maximal when responses to unisensory modalities are weak. The present study investigated whether audiovisual facilitation can be observed in congenital amusia, a music-specific disorder primarily ascribed to impairments of pitch processing. Amusic individuals and their matched controls performed two tasks. In Task 1, they were required to detect auditory, visual, or audiovisual stimuli as rapidly as possible. In Task 2, they were required to detect as accurately and as rapidly as possible a pitch change within an otherwise monotonic 5-tone sequence that was presented either only auditorily (A condition), or simultaneously with a temporally congruent, but otherwise uninformative visual stimulus (AV condition). Results of Task 1 showed that amusics exhibit typical auditory and visual detection, and typical audiovisual integration capacities: both amusics and controls exhibited shorter response times for audiovisual stimuli than for either auditory stimuli or visual stimuli. Results of Task 2 revealed that both groups benefited from simultaneous uninformative visual stimuli to detect pitch changes: accuracy was higher and response times shorter in the AV condition than in the A condition. The audiovisual improvements of response times were observed for different pitch interval sizes depending on the group. These results suggest that both typical listeners and amusic individuals can benefit from multisensory integration to improve their pitch processing abilities and that this benefit varies as a function of task difficulty. These findings constitute the first step towards the perspective to exploit multisensory paradigms to reduce pitch-related deficits in congenital amusia, notably by suggesting that audiovisual paradigms are effective in an appropriate range of unimodal performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Detection of changes in gene regulatory patterns, elicited by perturbations of the Hsp90 molecular chaperone complex, by visualizing multiple experiments with an animation

PubMed Central

2011-01-01

Background To make sense out of gene expression profiles, such analyses must be pushed beyond the mere listing of affected genes. For example, if a group of genes persistently display similar changes in expression levels under particular experimental conditions, and the proteins encoded by these genes interact and function in the same cellular compartments, this could be taken as very strong indicators for co-regulated protein complexes. One of the key requirements is having appropriate tools to detect such regulatory patterns. Results We have analyzed the global adaptations in gene expression patterns in the budding yeast when the Hsp90 molecular chaperone complex is perturbed either pharmacologically or genetically. We integrated these results with publicly accessible expression, protein-protein interaction and intracellular localization data. But most importantly, all experimental conditions were simultaneously and dynamically visualized with an animation. This critically facilitated the detection of patterns of gene expression changes that suggested underlying regulatory networks that a standard analysis by pairwise comparison and clustering could not have revealed. Conclusions The results of the animation-assisted detection of changes in gene regulatory patterns make predictions about the potential roles of Hsp90 and its co-chaperone p23 in regulating whole sets of genes. The simultaneous dynamic visualization of microarray experiments, represented in networks built by integrating one's own experimental with publicly accessible data, represents a powerful discovery tool that allows the generation of new interpretations and hypotheses. PMID:21672238

Liquid-to-gel transition for visual and tactile detection of biological analytes.

PubMed

Fedotova, Tatiana A; Kolpashchikov, Dmitry M

2017-11-23

So far all visual and instrument-free methods have been based on a color change. However, colorimetric assays cannot be used by blind or color-blind people. Here we introduce a liquid-to-gel transition as a general output platform. The signal output (a piece of gel) can be unambiguously distinguished from liquid both visually and by touch. This approach promises to contribute to the development of an accessible environment for visually impaired persons.

Interrupted Visual Searches Reveal Volatile Search Memory

ERIC Educational Resources Information Center

Shen, Y. Jeremy; Jiang, Yuhong V.

2006-01-01

This study investigated memory from interrupted visual searches. Participants conducted a change detection search task on polygons overlaid on scenes. Search was interrupted by various disruptions, including unfilled delay, passive viewing of other scenes, and additional search on new displays. Results showed that performance was unaffected by…

Spatial and temporal coherence in perceptual binding

PubMed Central

Blake, Randolph; Yang, Yuede

1997-01-01

Component visual features of objects are registered by distributed patterns of activity among neurons comprising multiple pathways and visual areas. How these distributed patterns of activity give rise to unified representations of objects remains unresolved, although one recent, controversial view posits temporal coherence of neural activity as a binding agent. Motivated by the possible role of temporal coherence in feature binding, we devised a novel psychophysical task that requires the detection of temporal coherence among features comprising complex visual images. Results show that human observers can more easily detect synchronized patterns of temporal contrast modulation within hybrid visual images composed of two components when those components are drawn from the same original picture. Evidently, time-varying changes within spatially coherent features produce more salient neural signals. PMID:9192701

Age-Related Changes in Temporal Allocation of Visual Attention: Evidence from the Rapid Serial Visual Presentation (RSVP) Paradigm

ERIC Educational Resources Information Center

Berger, Carole; Valdois, Sylviane; Lallier, Marie; Donnadieu, Sophie

2015-01-01

The present study explored the temporal allocation of attention in groups of 8-year-old children, 10-year-old children, and adults performing a rapid serial visual presentation task. In a dual-condition task, participants had to detect a briefly presented target (T2) after identifying an initial target (T1) embedded in a random series of…

Metal-enhanced fluorescence/visual bimodal platform for multiplexed ultrasensitive detection of microRNA with reusable paper analytical devices.

PubMed

Liang, Linlin; Lan, Feifei; Yin, Xuemei; Ge, Shenguang; Yu, Jinghua; Yan, Mei

2017-09-15

Convenient biosensor for simultaneous multi-analyte detection was increasingly required in biological analysis. A novel flower-like silver (FLS)-enhanced fluorescence/visual bimodal platform for the ultrasensitive detection of multiple miRNAs was successfully constructed for the first time based on the principle of multi-channel microfluidic paper-based analytical devices (µPADs). Fluorophore-functionalized DNA 1 (DNA 1 -N-CDs) was combined with FLS, which was hybridized with quencher-carrying strand (DNA 2 -CeO 2 ) to form FLS-enhanced fluorescence biosensor. Upon the addition of the target miRNA, the fluorescent intensity of DNA 1 -N-CDs within the proximity of the FLS was strengthened. The disengaged DNA/CeO 2 complex could result in color change after joining H 2 O 2 , leading to real-time visual detection of miRNA firstly. If necessary, then the fluorescence method was applied for a accurate determination. In this strategy, the growth of FLS in µPADs not only reduced the background fluorescence but also provided an enrichment of "hot spots" for surface enhanced fluorescence detection of miRNAs. Results also showed versatility of the FLS in the enhancement of sensitivity and selectivity of the miRNA biosensor. Remarkably, this biosensor could detect as low as 0.03fM miRNA210 and 0.06fM miRNA21. Interestingly, the proposed biosensor also possessed good capability of recycling in three cycles upon change of the supplementation of DNA 2 -CeO 2 and visual substitutive device. This method opened new opportunities for further studies of miRNA related bioprocesses and will provide a new instrument for simultaneous detection of multiple low-level biomarkers. Copyright © 2017 Elsevier B.V. All rights reserved.

2,3,7,8-TCDD effects on visual structure and function in swim-up rainbow trout

USGS Publications Warehouse

Carvalho, Paulo S. M.

2004-01-01

An understanding of mechanisms of contaminant effects across levels of biological organization is essential in ecotoxicology if we are to generate predictive models for population-level effects. We applied a suite of biochemical, histological, and behavioral end points related to visual structure and function and foraging behavior to evaluate effects of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) on swim-up rainbow trout. We detected a dose-dependent decrease in densities of retinal ganglion cells (RGC), key retinal neurons that link the eye with the brain. These changes resulted in corresponding deficits in visual/motor function including reductions in visual acuity and in scotopic and photopic thresholds due to TCDD. The loss of RGCs suggests an increase in convergence of synapses from photoreceptors to RGCs as a cellular mechanism for the visual deficits. Dose-dependent increases in immunohistochemical detection of CYP1A protein in the vasculature of the brain and eye choroid was proportional with decreased ganglion cell densities in the retina. TCDD-induced AHR-regulated effects on these tissues might be involved in the detected decrease in ganglion cell densities. Prey capture rate decreased after TCDD exposure only at the highest treatment groups evaluated. Collectively, these results show that TCDD causes biochemical and structural changes in the eye and brain of rainbow trout that are associated with behavioral deficits leading to decreased individual fitness.

Optical defocus: differential effects on size and contrast letter recognition thresholds.

PubMed

Rabin, J

1994-02-01

To determine if optical defocus produces a greater reduction in visual acuity or small-letter contrast sensitivity. Letter charts were used to measure visual acuity and small-letter contrast sensitivity (20/25 Snellen equivalent) as a function of optical defocus. Letter size (acuity) and contrast (contrast sensitivity) were varied in equal logarithmic steps to make the task the same for the two types of measurement. Both visual acuity and contrast sensitivity declined with optical defocus, but the effect was far greater in the contrast domain. However, measurement variability also was greater for contrast sensitivity. After correction for this variability, measurement in the contrast domain still proved to be a more sensitive (1.75x) index of optical defocus. Small-letter contrast sensitivity is a powerful technique for detecting subtle amounts of optical defocus. This adjunctive approach may be useful when there are small changes in resolution that are not detected by standard measures of visual acuity. Potential applications include evaluating the course of vision in refractive surgery, classification of cataracts, detection of corneal or macular edema, and detection of visual loss in the aging eye. Evaluation of candidates for occupations requiring unique visual abilities also may be enhanced by measuring resolution in the contrast domain.

Colorimetric detection of cholesterol based on enzyme modified gold nanoparticles

NASA Astrophysics Data System (ADS)

Nirala, Narsingh R.; Saxena, Preeti S.; Srivastava, Anchal

2018-02-01

We develop a simple colorimetric method for determination of free cholesterol in aqueous solution based on functionalized gold nanoparticles with cholesterol oxidase. Functionalized gold nanoparticles interact with free cholesterol to produce H2O2 in proportion to the level of cholesterol visually is being detected. The quenching in optical properties and agglomeration of functionalized gold nanoparticles play a key role in cholesterol sensing due to the electron accepting property of H2O2. While the lower ranges of cholesterol (lower detection limit i.e. 0.2 mg/dL) can be effectively detected using fluorescence study, the absorption study attests evident visual color change which becomes effective for detection of higher ranges of cholesterol (lower detection limit i.e. 19 mg/dL). The shades of red gradually change to blue/purple as the level of cholesterol detected (as evident at 100 mg/dL) using unaided eye without the use of expensive instruments. The potential of the proposed method to be applied in the field is shown by the proposed cholesterol measuring color wheel.

Visual acuity loss and OCT changes as initial signs of leukaemia

PubMed Central

Ortiz, Jose M; Ruiz-Moreno, Jose M; Pozo-Martos, Paola; Montero, Javier A

2010-01-01

AIM To report two cases where decreased visual acuity was the first symptom of leukaemia and optical coherence tomography (OCT) allowed identification and localization of the retinal lesions. METHODS Retrospective, interventional, case reports. RESULTS One case of lymphoblastic acute leukaemia and chronic lymphoid leukaemia were diagnosed following decreased visual acuity. OCT showed macular serous detachment in the first case. The second case presented hypo fluorescent retinal infiltrates which appeared as hyper reflective lesions by OCT. Retinal changes disappeared and visual acuity was recovered following complete remission of the neoplasm. CONCLUSION OCT is a valuable, non invasive diagnostic tool permitting detection, localization and follow-up of ocular dissemination of neoplasms. PMID:22553573

Prestimulus EEG Power Predicts Conscious Awareness But Not Objective Visual Performance

PubMed Central

Veniero, Domenica

2017-01-01

Abstract Prestimulus oscillatory neural activity has been linked to perceptual outcomes during performance of psychophysical detection and discrimination tasks. Specifically, the power and phase of low frequency oscillations have been found to predict whether an upcoming weak visual target will be detected or not. However, the mechanisms by which baseline oscillatory activity influences perception remain unclear. Recent studies suggest that the frequently reported negative relationship between α power and stimulus detection may be explained by changes in detection criterion (i.e., increased target present responses regardless of whether the target was present/absent) driven by the state of neural excitability, rather than changes in visual sensitivity (i.e., more veridical percepts). Here, we recorded EEG while human participants performed a luminance discrimination task on perithreshold stimuli in combination with single-trial ratings of perceptual awareness. Our aim was to investigate whether the power and/or phase of prestimulus oscillatory activity predict discrimination accuracy and/or perceptual awareness on a trial-by-trial basis. Prestimulus power (3–28 Hz) was inversely related to perceptual awareness ratings (i.e., higher ratings in states of low prestimulus power/high excitability) but did not predict discrimination accuracy. In contrast, prestimulus oscillatory phase did not predict awareness ratings or accuracy in any frequency band. These results provide evidence that prestimulus α power influences the level of subjective awareness of threshold visual stimuli but does not influence visual sensitivity when a decision has to be made regarding stimulus features. Hence, we find a clear dissociation between the influence of ongoing neural activity on conscious awareness and objective performance. PMID:29255794

Visual detection of nucleic acids based on Mie scattering and the magnetophoretic effect.

PubMed

Zhao, Zichen; Chen, Shan; Ho, John Kin Lim; Chieng, Ching-Chang; Chen, Ting-Hsuan

2015-12-07

Visual detection of nucleic acid biomarkers is a simple and convenient approach to point-of-care applications. However, issues of sensitivity and the handling of complex bio-fluids have posed challenges. Here we report on a visual method detecting nucleic acids using Mie scattering of polystyrene microparticles and the magnetophoretic effect. Magnetic microparticles (MMPs) and polystyrene microparticles (PMPs) were surface-functionalised with oligonucleotide probes, which can hybridise with target oligonucleotides in juxtaposition and lead to the formation of MMPs-targets-PMPs sandwich structures. Using an externally applied magnetic field, the magnetophoretic effect attracts the sandwich structure to the sidewall, which reduces the suspended PMPs and leads to a change in the light transmission via the Mie scattering. Based on the high extinction coefficient of the Mie scattering (∼3 orders of magnitude greater than that of the commonly used gold nanoparticles), our results showed the limit of detection to be 4 pM using a UV-Vis spectrometer or 10 pM by direct visual inspection. Meanwhile, we also demonstrated that this method is compatible with multiplex assays and detection in complex bio-fluids, such as whole blood or a pool of nucleic acids, without purification in advance. With a simplified operation procedure, low instrumentation requirement, high sensitivity and compatibility with complex bio-fluids, this method provides an ideal solution for visual detection of nucleic acids in resource-limited settings.

The Vividness of Happiness in Dynamic Facial Displays of Emotion

PubMed Central

Becker, D. Vaughn; Neel, Rebecca; Srinivasan, Narayanan; Neufeld, Samantha; Kumar, Devpriya; Fouse, Shannon

2012-01-01

Rapid identification of facial expressions can profoundly affect social interactions, yet most research to date has focused on static rather than dynamic expressions. In four experiments, we show that when a non-expressive face becomes expressive, happiness is detected more rapidly anger. When the change occurs peripheral to the focus of attention, however, dynamic anger is better detected when it appears in the left visual field (LVF), whereas dynamic happiness is better detected in the right visual field (RVF), consistent with hemispheric differences in the processing of approach- and avoidance-relevant stimuli. The central advantage for happiness is nevertheless the more robust effect, persisting even when information of either high or low spatial frequency is eliminated. Indeed, a survey of past research on the visual search for emotional expressions finds better support for a happiness detection advantage, and the explanation may lie in the coevolution of the signal and the receiver. PMID:22247755

Is visual activation associated with changes in cerebral high-energy phosphate levels?

PubMed

van de Bank, Bart L; Maas, Marnix C; Bains, Lauren J; Heerschap, Arend; Scheenen, Tom W J

2018-03-23

Phosphorus magnetic resonance spectroscopy ( 31 P MRS) has been employed before to assess phosphocreatine (PCr) and other high-energy phosphates in the visual cortex during visual stimulation with inconsistent results. We performed functional 31 P MRS imaging in the visual cortex and control regions during a visual stimulation paradigm at an unprecedented sensitivity, exploiting a dedicated RF coil design at a 7 T MR system. Visual stimulation in a 3 min 24 s on-off paradigm in eight young healthy adults generated a clear BOLD effect with traditional 1 H functional MRI in the visual cortex (average z score 9.9 ± 0.2). However, no significant event-related changes in any of the 31 P metabolite concentrations, linewidths (7.9 ± 1.8 vs 7.8 ± 1.9 Hz) or tissue pH (7.07 ± 0.13 vs 7.06 ± 0.07) were detectable. Overall, our study of 31 P MRSI in 15 cm 3 voxels had a detection threshold for changes in PCr, Pi and γ-ATP between stimulation and rest of 5, 17 and 10%, respectively. In individual subjects, the mean coefficients of variance for PCr and Pi levels of control voxels were 6 ± 3 and 19 ± 8% (three time point average of 3 min 24 s). Altogether this indicates that energy supply for neuronal activation at this temporal resolution does not drain global PCr resources.

Recognition intent and visual word recognition.

PubMed

Wang, Man-Ying; Ching, Chi-Le

2009-03-01

This study adopted a change detection task to investigate whether and how recognition intent affects the construction of orthographic representation in visual word recognition. Chinese readers (Experiment 1-1) and nonreaders (Experiment 1-2) detected color changes in radical components of Chinese characters. Explicit recognition demand was imposed in Experiment 2 by an additional recognition task. When the recognition was implicit, a bias favoring the radical location informative of character identity was found in Chinese readers (Experiment 1-1), but not nonreaders (Experiment 1-2). With explicit recognition demands, the effect of radical location interacted with radical function and word frequency (Experiment 2). An estimate of identification performance under implicit recognition was derived in Experiment 3. These findings reflect the joint influence of recognition intent and orthographic regularity in shaping readers' orthographic representation. The implication for the role of visual attention in word recognition was also discussed.

Faces Do Not Capture Special Attention in Children with Autism Spectrum Disorder: A Change Blindness Study

ERIC Educational Resources Information Center

Kikuchi, Yukiko; Senju, Atsushi; Tojo, Yoshikuni; Osanai, Hiroo; Hasegawa, Toshikazu

2009-01-01

Two experiments investigated attention of children with autism spectrum disorder (ASD) to faces and objects. In both experiments, children (7- to 15-year-olds) detected the difference between 2 visual scenes. Results in Experiment 1 revealed that typically developing children (n = 16) detected the change in faces faster than in objects, whereas…

Cest Analysis: Automated Change Detection from Very-High Remote Sensing Images

NASA Astrophysics Data System (ADS)

Ehlers, M.; Klonus, S.; Jarmer, T.; Sofina, N.; Michel, U.; Reinartz, P.; Sirmacek, B.

2012-08-01

A fast detection, visualization and assessment of change in areas of crisis or catastrophes are important requirements for coordination and planning of help. Through the availability of new satellites and/or airborne sensors with very high spatial resolutions (e.g., WorldView, GeoEye) new remote sensing data are available for a better detection, delineation and visualization of change. For automated change detection, a large number of algorithms has been proposed and developed. From previous studies, however, it is evident that to-date no single algorithm has the potential for being a reliable change detector for all possible scenarios. This paper introduces the Combined Edge Segment Texture (CEST) analysis, a decision-tree based cooperative suite of algorithms for automated change detection that is especially designed for the generation of new satellites with very high spatial resolution. The method incorporates frequency based filtering, texture analysis, and image segmentation techniques. For the frequency analysis, different band pass filters can be applied to identify the relevant frequency information for change detection. After transforming the multitemporal images via a fast Fourier transform (FFT) and applying the most suitable band pass filter, different methods are available to extract changed structures: differencing and correlation in the frequency domain and correlation and edge detection in the spatial domain. Best results are obtained using edge extraction. For the texture analysis, different 'Haralick' parameters can be calculated (e.g., energy, correlation, contrast, inverse distance moment) with 'energy' so far providing the most accurate results. These algorithms are combined with a prior segmentation of the image data as well as with morphological operations for a final binary change result. A rule-based combination (CEST) of the change algorithms is applied to calculate the probability of change for a particular location. CEST was tested with high-resolution satellite images of the crisis areas of Darfur (Sudan). CEST results are compared with a number of standard algorithms for automated change detection such as image difference, image ratioe, principal component analysis, delta cue technique and post classification change detection. The new combined method shows superior results averaging between 45% and 15% improvement in accuracy.

Driver Distraction Using Visual-Based Sensors and Algorithms.

PubMed

Fernández, Alberto; Usamentiaga, Rubén; Carús, Juan Luis; Casado, Rubén

2016-10-28

Driver distraction, defined as the diversion of attention away from activities critical for safe driving toward a competing activity, is increasingly recognized as a significant source of injuries and fatalities on the roadway. Additionally, the trend towards increasing the use of in-vehicle information systems is critical because they induce visual, biomechanical and cognitive distraction and may affect driving performance in qualitatively different ways. Non-intrusive methods are strongly preferred for monitoring distraction, and vision-based systems have appeared to be attractive for both drivers and researchers. Biomechanical, visual and cognitive distractions are the most commonly detected types in video-based algorithms. Many distraction detection systems only use a single visual cue and therefore, they may be easily disturbed when occlusion or illumination changes appear. Moreover, the combination of these visual cues is a key and challenging aspect in the development of robust distraction detection systems. These visual cues can be extracted mainly by using face monitoring systems but they should be completed with more visual cues (e.g., hands or body information) or even, distraction detection from specific actions (e.g., phone usage). Additionally, these algorithms should be included in an embedded device or system inside a car. This is not a trivial task and several requirements must be taken into account: reliability, real-time performance, low cost, small size, low power consumption, flexibility and short time-to-market. The key points for the development and implementation of sensors to carry out the detection of distraction will also be reviewed. This paper shows a review of the role of computer vision technology applied to the development of monitoring systems to detect distraction. Some key points considered as both future work and challenges ahead yet to be solved will also be addressed.

Driver Distraction Using Visual-Based Sensors and Algorithms

PubMed Central

Fernández, Alberto; Usamentiaga, Rubén; Carús, Juan Luis; Casado, Rubén

2016-01-01

Driver distraction, defined as the diversion of attention away from activities critical for safe driving toward a competing activity, is increasingly recognized as a significant source of injuries and fatalities on the roadway. Additionally, the trend towards increasing the use of in-vehicle information systems is critical because they induce visual, biomechanical and cognitive distraction and may affect driving performance in qualitatively different ways. Non-intrusive methods are strongly preferred for monitoring distraction, and vision-based systems have appeared to be attractive for both drivers and researchers. Biomechanical, visual and cognitive distractions are the most commonly detected types in video-based algorithms. Many distraction detection systems only use a single visual cue and therefore, they may be easily disturbed when occlusion or illumination changes appear. Moreover, the combination of these visual cues is a key and challenging aspect in the development of robust distraction detection systems. These visual cues can be extracted mainly by using face monitoring systems but they should be completed with more visual cues (e.g., hands or body information) or even, distraction detection from specific actions (e.g., phone usage). Additionally, these algorithms should be included in an embedded device or system inside a car. This is not a trivial task and several requirements must be taken into account: reliability, real-time performance, low cost, small size, low power consumption, flexibility and short time-to-market. The key points for the development and implementation of sensors to carry out the detection of distraction will also be reviewed. This paper shows a review of the role of computer vision technology applied to the development of monitoring systems to detect distraction. Some key points considered as both future work and challenges ahead yet to be solved will also be addressed. PMID:27801822

Personality and attention: Levels of neuroticism and extraversion can predict attentional performance during a change detection task.

PubMed

Hahn, Sowon; Buttaccio, Daniel R; Hahn, Jungwon; Lee, Taehun

2015-01-01

The present study demonstrates that levels of extraversion and neuroticism can predict attentional performance during a change detection task. After completing a change detection task built on the flicker paradigm, participants were assessed for personality traits using the Revised Eysenck Personality Questionnaire (EPQ-R). Multiple regression analyses revealed that higher levels of extraversion predict increased change detection accuracies, while higher levels of neuroticism predict decreased change detection accuracies. In addition, neurotic individuals exhibited decreased sensitivity A' and increased fixation dwell times. Hierarchical regression analyses further revealed that eye movement measures mediate the relationship between neuroticism and change detection accuracies. Based on the current results, we propose that neuroticism is associated with decreased attentional control over the visual field, presumably due to decreased attentional disengagement. Extraversion can predict increased attentional performance, but the effect is smaller than the relationship between neuroticism and attention.

Classification of change detection and change blindness from near-infrared spectroscopy signals

NASA Astrophysics Data System (ADS)

Tanaka, Hirokazu; Katura, Takusige

2011-08-01

Using a machine-learning classification algorithm applied to near-infrared spectroscopy (NIRS) signals, we classify a success (change detection) or a failure (change blindness) in detecting visual changes for a change-detection task. Five subjects perform a change-detection task, and their brain activities are continuously monitored. A support-vector-machine algorithm is applied to classify the change-detection and change-blindness trials, and correct classification probability of 70-90% is obtained for four subjects. Two types of temporal shapes in classification probabilities are found: one exhibiting a maximum value after the task is completed (postdictive type), and another exhibiting a maximum value during the task (predictive type). As for the postdictive type, the classification probability begins to increase immediately after the task completion and reaches its maximum in about the time scale of neuronal hemodynamic response, reflecting a subjective report of change detection. As for the predictive type, the classification probability shows an increase at the task initiation and is maximal while subjects are performing the task, predicting the task performance in detecting a change. We conclude that decoding change detection and change blindness from NIRS signal is possible and argue some future applications toward brain-machine interfaces.

Incidental learning of probability information is differentially affected by the type of visual working memory representation.

PubMed

van Lamsweerde, Amanda E; Beck, Melissa R

2015-12-01

In this study, we investigated whether the ability to learn probability information is affected by the type of representation held in visual working memory. Across 4 experiments, participants detected changes to displays of coloured shapes. While participants detected changes in 1 dimension (e.g., colour), a feature from a second, nonchanging dimension (e.g., shape) predicted which object was most likely to change. In Experiments 1 and 3, items could be grouped by similarity in the changing dimension across items (e.g., colours and shapes were repeated in the display), while in Experiments 2 and 4 items could not be grouped by similarity (all features were unique). Probability information from the predictive dimension was learned and used to increase performance, but only when all of the features within a display were unique (Experiments 2 and 4). When it was possible to group by feature similarity in the changing dimension (e.g., 2 blue objects appeared within an array), participants were unable to learn probability information and use it to improve performance (Experiments 1 and 3). The results suggest that probability information can be learned in a dimension that is not explicitly task-relevant, but only when the probability information is represented with the changing dimension in visual working memory. (c) 2015 APA, all rights reserved).

The Attentional Boost Effect: Transient increases in attention to one task enhance performance in a second task.

PubMed

Swallow, Khena M; Jiang, Yuhong V

2010-04-01

Recent work on event perception suggests that perceptual processing increases when events change. An important question is how such changes influence the way other information is processed, particularly during dual-task performance. In this study, participants monitored a long series of distractor items for an occasional target as they simultaneously encoded unrelated background scenes. The appearance of an occasional target could have two opposite effects on the secondary task: It could draw attention away from the second task, or, as a change in the ongoing event, it could improve secondary task performance. Results were consistent with the second possibility. Memory for scenes presented simultaneously with the targets was better than memory for scenes that preceded or followed the targets. This effect was observed when the primary detection task involved visual feature oddball detection, auditory oddball detection, and visual color-shape conjunction detection. It was eliminated when the detection task was omitted, and when it required an arbitrary response mapping. The appearance of occasional, task-relevant events appears to trigger a temporal orienting response that facilitates processing of concurrently attended information (Attentional Boost Effect). Copyright 2009 Elsevier B.V. All rights reserved.

The Attentional Boost Effect: Transient Increases in Attention to One Task Enhance Performance in a Second Task

PubMed Central

Swallow, Khena M.; Jiang, Yuhong V.

2009-01-01

Recent work on event perception suggests that perceptual processing increases when events change. An important question is how such changes influence the way other information is processed, particularly during dual-task performance. In this study, participants monitored a long series of distractor items for an occasional target as they simultaneously encoded unrelated background scenes. The appearance of an occasional target could have two opposite effects on the secondary task: It could draw attention away from the second task, or, as a change in the ongoing event, it could improve secondary task performance. Results were consistent with the second possibility. Memory for scenes presented simultaneously with the targets was better than memory for scenes that preceded or followed the targets. This effect was observed when the primary detection task involved visual feature oddball detection, auditory oddball detection, and visual color-shape conjunction detection. It was eliminated when the detection task was omitted, and when it required an arbitrary response mapping. The appearance of occasional, task-relevant events appears to trigger a temporal orienting response that facilitates processing of concurrently attended information (Attentional Boost Effect). PMID:20080232

Automatic Processing of Changes in Facial Emotions in Dysphoria: A Magnetoencephalography Study.

PubMed

Xu, Qianru; Ruohonen, Elisa M; Ye, Chaoxiong; Li, Xueqiao; Kreegipuu, Kairi; Stefanics, Gabor; Luo, Wenbo; Astikainen, Piia

2018-01-01

It is not known to what extent the automatic encoding and change detection of peripherally presented facial emotion is altered in dysphoria. The negative bias in automatic face processing in particular has rarely been studied. We used magnetoencephalography (MEG) to record automatic brain responses to happy and sad faces in dysphoric (Beck's Depression Inventory ≥ 13) and control participants. Stimuli were presented in a passive oddball condition, which allowed potential negative bias in dysphoria at different stages of face processing (M100, M170, and M300) and alterations of change detection (visual mismatch negativity, vMMN) to be investigated. The magnetic counterpart of the vMMN was elicited at all stages of face processing, indexing automatic deviance detection in facial emotions. The M170 amplitude was modulated by emotion, response amplitudes being larger for sad faces than happy faces. Group differences were found for the M300, and they were indexed by two different interaction effects. At the left occipital region of interest, the dysphoric group had larger amplitudes for sad than happy deviant faces, reflecting negative bias in deviance detection, which was not found in the control group. On the other hand, the dysphoric group showed no vMMN to changes in facial emotions, while the vMMN was observed in the control group at the right occipital region of interest. Our results indicate that there is a negative bias in automatic visual deviance detection, but also a general change detection deficit in dysphoria.

Using Morphed Images to Study Visual Detection of Cutaneous Melanoma Symptom Evolution

ERIC Educational Resources Information Center

Dalianis, Elizabeth A.; Critchfield, Thomas S.; Howard, Niki L.; Jordan, J. Scott; Derenne, Adam

2011-01-01

Early detection attenuates otherwise high mortality from the skin cancer melanoma, and although major melanoma symptoms are well defined, little is known about how individuals detect them. Previous research has focused on identifying static stimuli as symptomatic vs. asymptomatic, whereas under natural conditions it is "changes" in skin lesions…

Correlation between language function and the left arcuate fasciculus detected by diffusion tensor imaging tractography after brain tumor surgery.

PubMed

Hayashi, Yutaka; Kinoshita, Masashi; Nakada, Mitsutoshi; Hamada, Jun-ichiro

2012-11-01

Disturbance of the arcuate fasciculus in the dominant hemisphere is thought to be associated with language-processing disorders, including conduction aphasia. Although the arcuate fasciculus can be visualized in vivo with diffusion tensor imaging (DTI) tractography, its involvement in functional processes associated with language has not been shown dynamically using DTI tractography. In the present study, to clarify the participation of the arcuate fasciculus in language functions, postoperative changes in the arcuate fasciculus detected by DTI tractography were evaluated chronologically in relation to postoperative changes in language function after brain tumor surgery. Preoperative and postoperative arcuate fasciculus area and language function were examined in 7 right-handed patients with a brain tumor in the left hemisphere located in proximity to part of the arcuate fasciculus. The arcuate fasciculus was depicted, and its area was calculated using DTI tractography. Language functions were measured using the Western Aphasia Battery (WAB). After tumor resection, visualization of the arcuate fasciculus was increased in 5 of the 7 patients, and the total WAB score improved in 6 of the 7 patients. The relative ratio of postoperative visualized area of the arcuate fasciculus to preoperative visualized area of the arcuate fasciculus was increased in association with an improvement in postoperative language function (p = 0.0039). The role of the left arcuate fasciculus in language functions can be evaluated chronologically in vivo by DTI tractography after brain tumor surgery. Because increased postoperative visualization of the fasciculus was significantly associated with postoperative improvement in language functions, the arcuate fasciculus may play an important role in language function, as previously thought. In addition, postoperative changes in the arcuate fasciculus detected by DTI tractography could represent a predicting factor for postoperative language-dependent functional outcomes in patients with brain tumor.

Highly sensitive on-site detection of glucose in human urine with naked eye based on enzymatic-like reaction mediated etching of gold nanorods.

PubMed

Zhang, Zhiyang; Chen, Zhaopeng; Cheng, Fangbin; Zhang, Yaowen; Chen, Lingxin

2017-03-15

Based on enzymatic-like reaction mediated etching of gold nanorods (GNRs), an ultrasensitive visual method was developed for on-site detection of urine glucose. With the catalysis of MoO 4 2 - , GNRs were efficiently etched by H 2 O 2 which was generated by glucose-glucose oxidase enzymatic reaction. The etching of GNRs lead to a blue-shift of logitudinal localized surface plasmon resonance of GNRs, accompanied by an obvious color change from blue to red. The peak-shift and the color change can be used for detection of glucose by the spectrophotometer and the naked eyes. Under optimal condition, an excellent sensitivity toward glucose is obtained with a detection limit of 0.1μM and a visual detection limit of 3μM in buffer solution. Benefiting from the high sensitivity, the successful colorimetric detection of glucose in original urine samples was achieved, which indicates the practical applicability to the on-site determination of urine glucose. Copyright © 2016 Elsevier B.V. All rights reserved.

Change detection and change blindness in pigeons (Columba livia).

PubMed

Herbranson, Walter T; Trinh, Yvan T; Xi, Patricia M; Arand, Mark P; Barker, Michael S K; Pratt, Theodore H

2014-05-01

Change blindness is a phenomenon in which even obvious details in a visual scene change without being noticed. Although change blindness has been studied extensively in humans, we do not yet know if it is a phenomenon that also occurs in other animals. Thus, investigation of change blindness in a nonhuman species may prove to be valuable by beginning to provide some insight into its ultimate causes. Pigeons learned a change detection task in which pecks to the location of a change in a sequence of stimulus displays were reinforced. They were worse at detecting changes if the stimulus displays were separated by a brief interstimulus interval, during which the display was blank, and this primary result matches the general pattern seen in previous studies of change blindness in humans. A second experiment attempted to identify specific stimulus characteristics that most reliably produced a failure to detect changes. Change detection was more difficult when interstimulus intervals were longer and when the change was iterated fewer times. ©2014 APA, all rights reserved.

Individual differences in rate of encoding predict estimates of visual short-term memory capacity (K).

PubMed

Jannati, Ali; McDonald, John J; Di Lollo, Vincent

2015-06-01

The capacity of visual short-term memory (VSTM) is commonly estimated by K scores obtained with a change-detection task. Contrary to common belief, K may be influenced not only by capacity but also by the rate at which stimuli are encoded into VSTM. Experiment 1 showed that, contrary to earlier conclusions, estimates of VSTM capacity obtained with a change-detection task are constrained by temporal limitations. In Experiment 2, we used change-detection and backward-masking tasks to obtain separate within-subject estimates of K and of rate of encoding, respectively. A median split based on rate of encoding revealed significantly higher K estimates for fast encoders. Moreover, a significant correlation was found between K and the estimated rate of encoding. The present findings raise the prospect that the reported relationships between K and such cognitive concepts as fluid intelligence may be mediated not only by VSTM capacity but also by rate of encoding. (c) 2015 APA, all rights reserved).

Retinal and Optic Nerve Degeneration in Patients with Multiple Sclerosis Followed up for 5 Years.

PubMed

Garcia-Martin, Elena; Ara, Jose R; Martin, Jesus; Almarcegui, Carmen; Dolz, Isabel; Vilades, Elisa; Gil-Arribas, Laura; Fernandez, Francisco J; Polo, Vicente; Larrosa, Jose M; Pablo, Luis E; Satue, Maria

2017-05-01

To quantify retinal nerve fiber layer (RNFL) changes in patients with multiple sclerosis (MS) and healthy controls with a 5-year follow-up and to analyze correlations between disability progression and RNFL degeneration. Observational and longitudinal study. One hundred patients with relapsing-remitting MS and 50 healthy controls. All participants underwent a complete ophthalmic and electrophysiologic exploration and were re-evaluated annually for 5 years. Visual acuity (Snellen chart), color vision (Ishihara pseudoisochromatic plates), visual field examination, optical coherence tomography (OCT), scanning laser polarimetry (SLP), and visual evoked potentials. Expanded Disability Status Scale (EDSS) scores, disease duration, treatments, prior optic neuritis episodes, and quality of life (QOL; based on the 54-item Multiple Sclerosis Quality of Life Scale score). Optical coherence tomography (OCT) revealed changes in all RNFL thicknesses in both groups. In the MS group, changes were detected in average thickness and in the mean deviation using the GDx-VCC nerve fiber analyzer (Laser Diagnostic Technologies, San Diego, CA) and in the P100 latency of visual evoked potentials; no changes were detected in visual acuity, color vision, or visual fields. Optical coherence tomography showed greater differences in the inferior and temporal RNFL thicknesses in both groups. In MS patients only, OCT revealed a moderate correlation between the increase in EDSS and temporal and superior RNFL thinning. Temporal RNFL thinning based on OCT results was correlated moderately with decreased QOL. Multiple sclerosis patients exhibit a progressive axonal loss in the optic nerve fiber layer. Retinal nerve fiber layer thinning based on OCT results is a useful marker for assessing MS progression and correlates with increased disability and reduced QOL. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Deficits in visual working-memory capacity and general cognition in African Americans with psychosis.

PubMed

Mathias, Samuel R; Knowles, Emma E M; Barrett, Jennifer; Beetham, Tamara; Leach, Olivia; Buccheri, Sebastiano; Aberizk, Katrina; Blangero, John; Poldrack, Russell A; Glahn, David C

2018-03-01

On average, patients with psychosis perform worse than controls on visual change-detection tasks, implying that psychosis is associated with reduced capacity of visual working memory (WM). In the present study, 79 patients diagnosed with various psychotic disorders and 166 controls, all African Americans, completed a change-detection task and several other neurocognitive measures. The aims of the study were to (1) determine whether we could observe a between-group difference in performance on the change-detection task in this sample; (2) establish whether such a difference could be specifically attributed to reduced WM capacity (k); and (3) estimate k in the context of the general cognitive deficit in psychosis. Consistent with previous studies, patients performed worse than controls on the change-detection task, on average. Bayesian hierarchical cognitive modeling of the data suggested that this between-group difference was driven by reduced k in patients, rather than differences in other psychologically meaningful model parameters (guessing behavior and lapse rate). Using the same modeling framework, we estimated the effect of psychosis on k while controlling for general intellectual ability (g, obtained from the other neurocognitive measures). The results suggested that reduced k in patients was stronger than predicted by the between-group difference in g. Moreover, a mediation analysis suggested that the relationship between psychosis and g (i.e., the general cognitive deficit) was mediated by k. The results were consistent with the idea that reduced k is a specific deficit in psychosis, which contributes to the general cognitive deficit. Copyright © 2017 Elsevier B.V. All rights reserved.

Age and Visual Information Processing.

ERIC Educational Resources Information Center

Gummerman, Kent; And Others

This paper reports on three studies concerned with aspects of human visual information processing. Study I was an effort to measure the duration of iconic storage using a partial report method in children ranging in age from 6 to 13 years. Study II was designed to detect age related changes in the rate of processing (perceptually encoding) letters…

The Development of Visual Working Memory Capacity during Early Childhood

ERIC Educational Resources Information Center

Simmering, Vanessa R.

2012-01-01

The change detection task has been used in dozens of studies with adults to measure visual working memory capacity. Two studies have recently tested children in this task, suggesting a gradual increase in capacity from 5 years to adulthood. These results contrast with findings from an infant looking paradigm suggesting that capacity reaches…

A Psychophysical Test of the Visual Pathway of Children with Autism

ERIC Educational Resources Information Center

Sanchez-Marin, Francisco J.; Padilla-Medina, Jose A.

2008-01-01

Signal detection psychophysical experiments were conducted to investigate the visual path of children with autism. Computer generated images with Gaussian noise were used. Simple signals, still and in motion were embedded in the background noise. The computer monitor was linearized to properly display the contrast changes. To our knowledge, this…

Effective communication of risks to young adults: using message framing and visual aids to increase condom use and STD screening.

PubMed

Garcia-Retamero, Rocio; Cokely, Edward T

2011-09-01

Sexually Transmitted Diseases (STDs)-including HIV/AIDS-are among the most common infectious diseases in young adults. How can we effectively promote prevention and detection of STDs in this high risk population? In a two-phase longitudinal experiment we examined the effects of a brief risk awareness intervention (i.e., a sexual health information brochure) in a large sample of sexually active young adults (n = 744). We assessed the influence of gain- and loss-framed messages, and visual aids, on affective reactions, risk perceptions, attitudes, behavioral intentions, and reported behaviors relating to the prevention and detection of STDs. Results indicate that gain-framed messages induced greater adherence for prevention behaviors (e.g., condom use), whereas loss-framed messages were more effective in promoting illness-detecting behaviors (e.g., making an appointment with a doctor to discuss about STD screening). The influence of the framed messages on prevention and detection of STDs was mediated by changes in participants' attitudes toward the health behaviors along with changes in their behavioral intentions. Moreover, when visual aids were added to the health information, both the gain- and loss-framed messages became equally and highly effective in promoting health behaviors. These results converge with other data indicating that well-constructed visual aids are often among the most highly effective, transparent, fast, memorable, and ethically desirable means of risk communication. Theoretical, economic, and public policy implications of these results are discussed. (c) 2011 APA, all rights reserved.

A platform for proactive, risk-based slope asset management, phase II.

DOT National Transportation Integrated Search

2015-03-01

The lidar visualization technique developed by this project enables highway managers to understand changes in slope characteristics : along highways. This change detection and analysis can be the basis of informed decisions for slope inspection and r...

A platform for proactive, risk-based slope asset management, phase II.

DOT National Transportation Integrated Search

2015-08-01

The lidar visualization technique developed by this project enables highway managers to understand changes : in slope characteristics along highways. This change detection and analysis can be the basis of informed : decisions for slope inspection and...

Endogenous modulation of human visual cortex activity improves perception at twilight.

PubMed

Cordani, Lorenzo; Tagliazucchi, Enzo; Vetter, Céline; Hassemer, Christian; Roenneberg, Till; Stehle, Jörg H; Kell, Christian A

2018-04-10

Perception, particularly in the visual domain, is drastically influenced by rhythmic changes in ambient lighting conditions. Anticipation of daylight changes by the circadian system is critical for survival. However, the neural bases of time-of-day-dependent modulation in human perception are not yet understood. We used fMRI to study brain dynamics during resting-state and close-to-threshold visual perception repeatedly at six times of the day. Here we report that resting-state signal variance drops endogenously at times coinciding with dawn and dusk, notably in sensory cortices only. In parallel, perception-related signal variance in visual cortices decreases and correlates negatively with detection performance, identifying an anticipatory mechanism that compensates for the deteriorated visual signal quality at dawn and dusk. Generally, our findings imply that decreases in spontaneous neural activity improve close-to-threshold perception.

The Tölz Temporal Topography Study: mapping the visual field across the life span. Part I: the topography of light detection and temporal-information processing.

PubMed

Poggel, Dorothe A; Treutwein, Bernhard; Calmanti, Claudia; Strasburger, Hans

2012-08-01

Temporal performance parameters vary across the visual field. Their topographical distributions relative to each other and relative to basic visual performance measures and their relative change over the life span are unknown. Our goal was to characterize the topography and age-related change of temporal performance. We acquired visual field maps in 95 healthy participants (age: 10-90 years): perimetric thresholds, double-pulse resolution (DPR), reaction times (RTs), and letter contrast thresholds. DPR and perimetric thresholds increased with eccentricity and age; the periphery showed a more pronounced age-related increase than the center. RT increased only slightly and uniformly with eccentricity. It remained almost constant up to the age of 60, a marked change occurring only above 80. Overall, age was a poor predictor of functionality. Performance decline could be explained only in part by the aging of the retina and optic media. In Part II, we therefore examine higher visual and cognitive functions.

Proactive interference from items previously stored in visual working memory.

PubMed

Makovski, Tal; Jiang, Yuhong V

2008-01-01

This study investigates the fate of information that was previously stored in visual working memory but that is no longer needed. Previous research has found inconsistent results, with some showing effective release of irrelevant information and others showing proactive interference. Using change detection tasks of colors or shapes, we show that participants tend to falsely classify a changed item as "no change" if it matches one of the memory items on the preceding trial. The interference is spatially specific: Memory for the preceding trial interferes more if it matches the feature value and the location of a test item than if it does not. Interference results from retaining information in visual working memory, since it is absent when items on the preceding trials are passively viewed, or are attended but not memorized. We conclude that people cannot fully eliminate unwanted visual information from current working memory tasks.

Threat as a feature in visual semantic object memory.

PubMed

Calley, Clifford S; Motes, Michael A; Chiang, H-Sheng; Buhl, Virginia; Spence, Jeffrey S; Abdi, Hervé; Anand, Raksha; Maguire, Mandy; Estevez, Leonardo; Briggs, Richard; Freeman, Thomas; Kraut, Michael A; Hart, John

2013-08-01

Threatening stimuli have been found to modulate visual processes related to perception and attention. The present functional magnetic resonance imaging (fMRI) study investigated whether threat modulates visual object recognition of man-made and naturally occurring categories of stimuli. Compared with nonthreatening pictures, threatening pictures of real items elicited larger fMRI BOLD signal changes in medial visual cortices extending inferiorly into the temporo-occipital (TO) "what" pathways. This region elicited greater signal changes for threatening items compared to nonthreatening from both the natural-occurring and man-made stimulus supraordinate categories, demonstrating a featural component to these visual processing areas. Two additional loci of signal changes within more lateral inferior TO areas (bilateral BA18 and 19 as well as the right ventral temporal lobe) were detected for a category-feature interaction, with stronger responses to man-made (category) threatening (feature) stimuli than to natural threats. The findings are discussed in terms of visual recognition of processing efficiently or rapidly groups of items that confer an advantage for survival. Copyright © 2012 Wiley Periodicals, Inc.

Consciousness of the first order in blindsight

PubMed Central

Sahraie, Arash; Hibbard, Paul B.; Trevethan, Ceri T.; Ritchie, Kay L.; Weiskrantz, Lawrence

2010-01-01

At suprathreshold levels, detection and awareness of visual stimuli are typically synonymous in nonclinical populations. But following postgeniculate lesions, some patients may perform above chance in forced-choice detection paradigms, while reporting not to see the visual events presented within their blind field. This phenomenon, termed “blindsight,” is intriguing because it demonstrates a dissociation between detection and perception. It is possible, however, for a blindsight patient to have some “feeling” of the occurrence of an event without seeing per se. This is termed blindsight type II to distinguish it from the type I, defined as discrimination capability in the total absence of any acknowledged awareness. Here we report on a well-studied patient, D.B., whose blindsight capabilities have been previously documented. We have found that D.B. is capable of detecting visual patterns defined by changes in luminance (first-order gratings) and those defined by contrast modulation of textured patterns (textured gratings; second-order stimuli) while being aware of the former but reporting no awareness of the latter. We have systematically investigated the parameters that could lead to visual awareness of the patterns and show that mechanisms underlying the subjective reports of visual awareness rely primarily on low spatial frequency, first-order spatial components of the image. PMID:21078979

Visual reaction time for chromaticity changes at constant luminance in different color representation systems

NASA Astrophysics Data System (ADS)

Jimenezdel Barco, L.; Jimenez, J. R.; Rubino, M.; Diaz, J. A.

1996-09-01

The results obtained by different authors show that when a color stimulus changes in both luminance and chromaticity, the visual reaction time (VRT) of an observer in detecting this chromatic change depends on nothing more than the luminance change and is regulated by Pieron's law. In the present work, we evaluate the VRT needed by an observer to detect the chromaticity difference between an adapting and variable stimulus. For this, we have used the experimental method of hue substitution, which allows us to maintain the luminance channel constant and thereby study the temporal response to changes only in chromaticity. The experiments were carried out with a CRT color monitor and the experimental results are expressed in different color-representation systems. The systems UCS-CIE 1964 (U*, V*, W*) and CIELUV show good correlations between the VRT and the chromaticity difference expressed in these systems, adjusting the VRT to an expression following Pieron's law: VRT-VRTon=k( Delta E)- beta .

Associations among visual acuity and vision- and health-related quality of life among patients in the multicenter uveitis steroid treatment trial.

PubMed

Frick, Kevin D; Drye, Lea T; Kempen, John H; Dunn, James P; Holland, Gary N; Latkany, Paul; Rao, Narsing A; Sen, H Nida; Sugar, Elizabeth A; Thorne, Jennifer E; Wang, Robert C; Holbrook, Janet T

2012-03-01

To evaluate the associations between visual acuity and self-reported visual function; visual acuity and health-related quality of life (QoL) metrics; a summary measure of self-reported visual function and health-related QoL; and individual domains of self-reported visual function and health-related QoL in patients with uveitis. Best-corrected visual acuity, vision-related functioning as assessed by the NEI VFQ-25, and health-related QoL as assessed by the SF-36 and EuroQoL EQ-5D questionnaires were obtained at enrollment in a clinical trial of uveitis treatments. Multivariate regression and Spearman correlations were used to evaluate associations between visual acuity, vision-related function, and health-related QoL. Among the 255 patients, median visual acuity in the better-seeing eyes was 20/25, the vision-related function score indicated impairment (median, 60), and health-related QoL scores were within the normal population range. Better visual acuity was predictive of higher visual function scores (P ≤ 0.001), a higher SF-36 physical component score, and a higher EQ-5D health utility score (P < 0.001). The vision-specific function score was predictive of all general health-related QoL (P < 0.001). The correlations between visual function score and general quality of life measures were moderate (ρ = 0.29-0.52). The vision-related function score correlated positively with visual acuity and moderately positively with general QoL measures. Cost-utility analyses relying on changes in generic healthy utility measures will be more likely to detect changes when there are clinically meaningful changes in vision-related function, rather than when there are only changes in visual acuity. (ClinicalTrials.gov number, NCT00132691.).

Grasp Preparation Improves Change Detection for Congruent Objects

ERIC Educational Resources Information Center

Symes, Ed; Tucker, Mike; Ellis, Rob; Vainio, Lari; Ottoboni, Giovanni

2008-01-01

A series of experiments provided converging support for the hypothesis that action preparation biases selective attention to action-congruent object features. When visual transients are masked in so-called "change-blindness scenes," viewers are blind to substantial changes between 2 otherwise identical pictures that flick back and forth. The…

Change Blindness Phenomena for Virtual Reality Display Systems.

PubMed

Steinicke, Frank; Bruder, Gerd; Hinrichs, Klaus; Willemsen, Pete

2011-09-01

In visual perception, change blindness describes the phenomenon that persons viewing a visual scene may apparently fail to detect significant changes in that scene. These phenomena have been observed in both computer-generated imagery and real-world scenes. Several studies have demonstrated that change blindness effects occur primarily during visual disruptions such as blinks or saccadic eye movements. However, until now the influence of stereoscopic vision on change blindness has not been studied thoroughly in the context of visual perception research. In this paper, we introduce change blindness techniques for stereoscopic virtual reality (VR) systems, providing the ability to substantially modify a virtual scene in a manner that is difficult for observers to perceive. We evaluate techniques for semiimmersive VR systems, i.e., a passive and active stereoscopic projection system as well as an immersive VR system, i.e., a head-mounted display, and compare the results to those of monoscopic viewing conditions. For stereoscopic viewing conditions, we found that change blindness phenomena occur with the same magnitude as in monoscopic viewing conditions. Furthermore, we have evaluated the potential of the presented techniques for allowing abrupt, and yet significant, changes of a stereoscopically displayed virtual reality environment.

Stimulus-dependent modulation of visual neglect in a touch-screen cancellation task.

PubMed

Keller, Ingo; Volkening, Katharina; Garbacenkaite, Ruta

2015-05-01

Patients with left-sided neglect frequently show omissions and repetitive behavior on cancellation tests. Using a touch-screen-based cancellation task, we tested how visual feedback and distracters influence the number of omissions and perseverations. Eighteen patients with left-sided visual neglect and 18 healthy controls performed four different cancellation tasks on an iPad touch screen: no feedback (the display did not change during the task), visual feedback (touched targets changed their color from black to green), visual feedback with distracters (20 distracters were evenly embedded in the display; detected targets changed their color from black to green), vanishing targets (touched targets disappeared from the screen). Except for the condition with vanishing targets, neglect patients had significantly more omissions and perseverations than healthy controls in the remaining three subtests. Both conditions providing feedback by changing the target color showed the highest number of omissions. Erasure of targets nearly diminished omissions completely. The highest rate of perseverations was observed in the no-feedback condition. The implementation of distracters led to a moderate number of perseverations. Visual feedback without distracters and vanishing targets abolished perseverations nearly completely. Visual feedback and the presence of distracters aggravated hemispatial neglect. This finding is compatible with impaired disengagement from the ipsilesional side as an important factor of visual neglect. Improvement of cancellation behavior with vanishing targets could have therapeutic implications. (c) 2015 APA, all rights reserved).

Changes in connectivity of the posterior default network node during visual processing in mild cognitive impairment: staged decline between normal aging and Alzheimer's disease.

PubMed

Krajcovicova, Lenka; Barton, Marek; Elfmarkova-Nemcova, Nela; Mikl, Michal; Marecek, Radek; Rektorova, Irena

2017-12-01

Visual processing difficulties are often present in Alzheimer's disease (AD), even in its pre-dementia phase (i.e. in mild cognitive impairment, MCI). The default mode network (DMN) modulates the brain connectivity depending on the specific cognitive demand, including visual processes. The aim of the present study was to analyze specific changes in connectivity of the posterior DMN node (i.e. the posterior cingulate cortex and precuneus, PCC/P) associated with visual processing in 17 MCI patients and 15 AD patients as compared to 18 healthy controls (HC) using functional magnetic resonance imaging. We used psychophysiological interaction (PPI) analysis to detect specific alterations in PCC connectivity associated with visual processing while controlling for brain atrophy. In the HC group, we observed physiological changes in PCC connectivity in ventral visual stream areas and with PCC/P during the visual task, reflecting the successful involvement of these regions in visual processing. In the MCI group, the PCC connectivity changes were disturbed and remained significant only with the anterior precuneus. In between-group comparison, we observed significant PPI effects in the right superior temporal gyrus in both MCI and AD as compared to HC. This change in connectivity may reflect ineffective "compensatory" mechanism present in the early pre-dementia stages of AD or abnormal modulation of brain connectivity due to the disease pathology. With the disease progression, these changes become more evident but less efficient in terms of compensation. This approach can separate the MCI from HC with 77% sensitivity and 89% specificity.

A Probabilistic Model of Visual Working Memory: Incorporating Higher Order Regularities into Working Memory Capacity Estimates

ERIC Educational Resources Information Center

Brady, Timothy F.; Tenenbaum, Joshua B.

2013-01-01

When remembering a real-world scene, people encode both detailed information about specific objects and higher order information like the overall gist of the scene. However, formal models of change detection, like those used to estimate visual working memory capacity, assume observers encode only a simple memory representation that includes no…

The Development of Visual Short-Term Memory for Multifeature Items during Middle childhood

ERIC Educational Resources Information Center

Riggs, Kevin J.; Simpson, Andrew; Potts, Thomas

2011-01-01

Visual short-term memory (VSTM) research suggests that the adult capacity is limited to three or four multifeature object representations. Despite evidence supporting a developmental increase in capacity, it remains unclear what the unit of capacity is in children. The current study employed the change detection paradigm to investigate both the…

Binding Objects to Locations: The Relationship between Object Files and Visual Working Memory

ERIC Educational Resources Information Center

Hollingworth, Andrew; Rasmussen, Ian P.

2010-01-01

The relationship between object files and visual working memory (VWM) was investigated in a new paradigm combining features of traditional VWM experiments (color change detection) and object-file experiments (memory for the properties of moving objects). Object-file theory was found to account for a key component of object-position binding in VWM:…

Optical temperature sensor using thermochromic semiconductors

DOEpatents

Kronberg, James W.

1996-01-01

An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually or by utilizing an optical fiber and an electrical sensing circuit.

Optical temperature sensor using thermochromic semiconductors

DOEpatents

Kronberg, James W.

1998-01-01

An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually using a sensor chip and an accompanying color card.

Optical temperature sensor using thermochromic semiconductors

DOEpatents

Kronberg, J.W.

1998-06-30

An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually using a sensor chip and an accompanying color card. 8 figs.

Neuroimaging Evidence for 2 Types of Plasticity in Association with Visual Perceptual Learning.

PubMed

Shibata, Kazuhisa; Sasaki, Yuka; Kawato, Mitsuo; Watanabe, Takeo

2016-09-01

Visual perceptual learning (VPL) is long-term performance improvement as a result of perceptual experience. It is unclear whether VPL is associated with refinement in representations of the trained feature (feature-based plasticity), improvement in processing of the trained task (task-based plasticity), or both. Here, we provide empirical evidence that VPL of motion detection is associated with both types of plasticity which occur predominantly in different brain areas. Before and after training on a motion detection task, subjects' neural responses to the trained motion stimuli were measured using functional magnetic resonance imaging. In V3A, significant response changes after training were observed specifically to the trained motion stimulus but independently of whether subjects performed the trained task. This suggests that the response changes in V3A represent feature-based plasticity in VPL of motion detection. In V1 and the intraparietal sulcus, significant response changes were found only when subjects performed the trained task on the trained motion stimulus. This suggests that the response changes in these areas reflect task-based plasticity. These results collectively suggest that VPL of motion detection is associated with the 2 types of plasticity, which occur in different areas and therefore have separate mechanisms at least to some degree. © The Author 2016. Published by Oxford University Press.

Removing own-limb visual input using mixed reality (MR) produces a "telescoping" illusion in healthy individuals.

PubMed

Thøgersen, Mikkel; Hansen, John; Arendt-Nielsen, Lars; Flor, Herta; Petrini, Laura

2018-07-16

The purpose of the present study was to assess changes in body perception when visual feedback was removed from the hand and arm with the purpose of resembling the visual deprivation arising from amputation. The illusion was created by removing the visual feedback from the participants' own left forearm using a mixed reality (MR) and green screen environment. Thirty healthy persons (15 female) participated in the study. Each subject experienced two MR conditions, one with and one without visual feedback from the left hand, and a baseline condition with normal vision of the limb (no MR). Body perception was assessed using proprioceptive drift, questionnaires on body perception, and thermal sensitivity measures (cold, warm, heat pain and cold pain detection thresholds). The proprioceptive drift showed a significant shift of the tip of the index finger (p<0.001) towards the elbow in the illusion condition (mean drift: -3.71 cm). Self-report showed a significant decrease in ownership (p<0.001), shift in perceptual distortions, (e.g. "It feels as if my lower arm has become shorter") (p=0.025), and changes in sensations of the hand (tingling, tickling) (p=0.025). A significant decrease was also observed in cold detection threshold (p<0.001), i.e. the detection threshold was cooler than for the control conditions. The proprioceptive drift together with the self-reported questionnaire showed that the participants felt a proximal retraction of their limb, resembling the telescoping experienced by phantom limb patients. The study highlights the influence of missing visual feedback and its possible contribution to phantom limb phenomena. Copyright © 2018 Elsevier B.V. All rights reserved.

Visual encoding and fixation target selection in free viewing: presaccadic brain potentials

PubMed Central

Nikolaev, Andrey R.; Jurica, Peter; Nakatani, Chie; Plomp, Gijs; van Leeuwen, Cees

2013-01-01

In scrutinizing a scene, the eyes alternate between fixations and saccades. During a fixation, two component processes can be distinguished: visual encoding and selection of the next fixation target. We aimed to distinguish the neural correlates of these processes in the electrical brain activity prior to a saccade onset. Participants viewed color photographs of natural scenes, in preparation for a change detection task. Then, for each participant and each scene we computed an image heat map, with temperature representing the duration and density of fixations. The temperature difference between the start and end points of saccades was taken as a measure of the expected task-relevance of the information concentrated in specific regions of a scene. Visual encoding was evaluated according to whether subsequent change was correctly detected. Saccades with larger temperature difference were more likely to be followed by correct detection than ones with smaller temperature differences. The amplitude of presaccadic activity over anterior brain areas was larger for correct detection than for detection failure. This difference was observed for short “scrutinizing” but not for long “explorative” saccades, suggesting that presaccadic activity reflects top-down saccade guidance. Thus, successful encoding requires local scanning of scene regions which are expected to be task-relevant. Next, we evaluated fixation target selection. Saccades “moving up” in temperature were preceded by presaccadic activity of higher amplitude than those “moving down”. This finding suggests that presaccadic activity reflects attention deployed to the following fixation location. Our findings illustrate how presaccadic activity can elucidate concurrent brain processes related to the immediate goal of planning the next saccade and the larger-scale goal of constructing a robust representation of the visual scene. PMID:23818877

Multisensory integration of speech sounds with letters vs. visual speech: only visual speech induces the mismatch negativity.

PubMed

Stekelenburg, Jeroen J; Keetels, Mirjam; Vroomen, Jean

2018-05-01

Numerous studies have demonstrated that the vision of lip movements can alter the perception of auditory speech syllables (McGurk effect). While there is ample evidence for integration of text and auditory speech, there are only a few studies on the orthographic equivalent of the McGurk effect. Here, we examined whether written text, like visual speech, can induce an illusory change in the perception of speech sounds on both the behavioural and neural levels. In a sound categorization task, we found that both text and visual speech changed the identity of speech sounds from an /aba/-/ada/ continuum, but the size of this audiovisual effect was considerably smaller for text than visual speech. To examine at which level in the information processing hierarchy these multisensory interactions occur, we recorded electroencephalography in an audiovisual mismatch negativity (MMN, a component of the event-related potential reflecting preattentive auditory change detection) paradigm in which deviant text or visual speech was used to induce an illusory change in a sequence of ambiguous sounds halfway between /aba/ and /ada/. We found that only deviant visual speech induced an MMN, but not deviant text, which induced a late P3-like positive potential. These results demonstrate that text has much weaker effects on sound processing than visual speech does, possibly because text has different biological roots than visual speech. © 2018 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

The role of auditory transient and deviance processing in distraction of task performance: a combined behavioral and event-related brain potential study

PubMed Central

Berti, Stefan

2013-01-01

Distraction of goal-oriented performance by a sudden change in the auditory environment is an everyday life experience. Different types of changes can be distracting, including a sudden onset of a transient sound and a slight deviation of otherwise regular auditory background stimulation. With regard to deviance detection, it is assumed that slight changes in a continuous sequence of auditory stimuli are detected by a predictive coding mechanisms and it has been demonstrated that this mechanism is capable of distracting ongoing task performance. In contrast, it is open whether transient detection—which does not rely on predictive coding mechanisms—can trigger behavioral distraction, too. In the present study, the effect of rare auditory changes on visual task performance is tested in an auditory-visual cross-modal distraction paradigm. The rare changes are either embedded within a continuous standard stimulation (triggering deviance detection) or are presented within an otherwise silent situation (triggering transient detection). In the event-related brain potentials, deviants elicited the mismatch negativity (MMN) while transients elicited an enhanced N1 component, mirroring pre-attentive change detection in both conditions but on the basis of different neuro-cognitive processes. These sensory components are followed by attention related ERP components including the P3a and the reorienting negativity (RON). This demonstrates that both types of changes trigger switches of attention. Finally, distraction of task performance is observable, too, but the impact of deviants is higher compared to transients. These findings suggest different routes of distraction allowing for the automatic processing of a wide range of potentially relevant changes in the environment as a pre-requisite for adaptive behavior. PMID:23874278

Pigeons (Columba livia) show change blindness in a color-change detection task.

PubMed

Herbranson, Walter T; Jeffers, Jacob S

2017-07-01

Change blindness is a phenomenon whereby changes to a stimulus are more likely go unnoticed under certain circumstances. Pigeons learned a change detection task, in which they observed sequential stimulus displays consisting of individual colors back-projected onto three response keys. The color of one response key changed during each sequence and pecks to the key that displayed the change were reinforced. Pigeons showed a change blindness effect, in that change detection accuracy was worse when there was an inter-stimulus interval interrupting the transition between consecutive stimulus displays. Birds successfully transferred to stimulus displays involving novel colors, indicating that pigeons learned a general change detection rule. Furthermore, analysis of responses to specific color combinations showed that pigeons could detect changes involving both spectral and non-spectral colors and that accuracy was better for changes involving greater differences in wavelength. These results build upon previous investigations of change blindness in both humans and pigeons and suggest that change blindness may be a general consequence of selective visual attention relevant to multiple species and stimulus dimensions.

Just one look: Direct gaze briefly disrupts visual working memory.

PubMed

Wang, J Jessica; Apperly, Ian A

2017-04-01

Direct gaze is a salient social cue that affords rapid detection. A body of research suggests that direct gaze enhances performance on memory tasks (e.g., Hood, Macrae, Cole-Davies, & Dias, Developmental Science, 1, 67-71, 2003). Nonetheless, other studies highlight the disruptive effect direct gaze has on concurrent cognitive processes (e.g., Conty, Gimmig, Belletier, George, & Huguet, Cognition, 115(1), 133-139, 2010). This discrepancy raises questions about the effects direct gaze may have on concurrent memory tasks. We addressed this topic by employing a change detection paradigm, where participants retained information about the color of small sets of agents. Experiment 1 revealed that, despite the irrelevance of the agents' eye gaze to the memory task at hand, participants were worse at detecting changes when the agents looked directly at them compared to when the agents looked away. Experiment 2 showed that the disruptive effect was relatively short-lived. Prolonged presentation of direct gaze led to recovery from the initial disruption, rather than a sustained disruption on change detection performance. The present study provides the first evidence that direct gaze impairs visual working memory with a rapidly-developing yet short-lived effect even when there is no need to attend to agents' gaze.

Detecting changes in real-world objects: The relationship between visual long-term memory and change blindness.

PubMed

Brady, Timothy F; Konkle, Talia; Oliva, Aude; Alvarez, George A

2009-01-01

A large body of literature has shown that observers often fail to notice significant changes in visual scenes, even when these changes happen right in front of their eyes. For instance, people often fail to notice if their conversation partner is switched to another person, or if large background objects suddenly disappear.1,2 These 'change blindness' studies have led to the inference that the amount of information we remember about each item in a visual scene may be quite low.1 However, in recent work we have demonstrated that long-term memory is capable of storing a massive number of visual objects with significant detail about each item.3 In the present paper we attempt to reconcile these findings by demonstrating that observers do not experience 'change blindness' with the real world objects used in our previous experiment if they are given sufficient time to encode each item. The results reported here suggest that one of the major causes of change blindness for real-world objects is a lack of encoding time or attention to each object (see also refs. 4 and 5).

[Topographic mapping of retinal function with a scanning laser ophthalmoscope and multifocal electroretinography using short M-sequences].

PubMed

Rudolph, G; Bechmann, M; Berninger, T; Kutschbach, E; Held, U; Tornow, R P; Kalpadakis, P; Zol'nikova, I V; Shamshinova, A M

2001-01-01

A new method of multifocal electroretinography making use of scanning laser ophthalmoscope with a wavelength of 630 nm (SLO-m-ERG), evoking short spatial visual stimuli on the retina, is proposed. Algorithm of presenting the visual stimuli and analysis of distribution of local electroretinograms on the surface of the retina is based on short m-sequences. Mathematical cross correlation analysis shows a three-dimensional distribution of bioelectrical activity of the retina in the central visual field. In normal subjects the cone bioelectrical activity is the maximum in the macular area (corresponding to the density of cone distribution) and absent in the blind spot. The method detects the slightest pathological changes in the retina under control of the site of stimulation and ophthalmoscopic picture of the fundus oculi. The site of the pathological process correlates with the topography of changes in bioelectrical activity of the examined retinal area in diseases of the macular area and pigmented retinitis detectable by ophthalmoscopy.

Two-dimensional hidden semantic information model for target saliency detection and eyetracking identification

NASA Astrophysics Data System (ADS)

Wan, Weibing; Yuan, Lingfeng; Zhao, Qunfei; Fang, Tao

2018-01-01

Saliency detection has been applied to the target acquisition case. This paper proposes a two-dimensional hidden Markov model (2D-HMM) that exploits the hidden semantic information of an image to detect its salient regions. A spatial pyramid histogram of oriented gradient descriptors is used to extract features. After encoding the image by a learned dictionary, the 2D-Viterbi algorithm is applied to infer the saliency map. This model can predict fixation of the targets and further creates robust and effective depictions of the targets' change in posture and viewpoint. To validate the model with a human visual search mechanism, two eyetrack experiments are employed to train our model directly from eye movement data. The results show that our model achieves better performance than visual attention. Moreover, it indicates the plausibility of utilizing visual track data to identify targets.

Near-infrared spectroscopy of the visual cortex in unilateral optic neuritis.

PubMed

Miki, Atsushi; Nakajima, Takashi; Takagi, Mineo; Usui, Tomoaki; Abe, Haruki; Liu, Chia-Shang J; Liu, Grant T

2005-02-01

To examine the occipital-lobe activation of patients with optic neuritis using near-infrared spectroscopy. Experimental study. NIRS was performed on five patients with acute unilateral optic neuritis during monocular visual stimulation. As controls, six normal subjects were also tested in the same manner. In the patients with optic neuritis, the changes in the hemoglobin concentrations (oxyhemoglobin, deoxyhemoglobin, and total hemoglobin) in the occipital lobe were found to be markedly reduced when the clinically affected eyes were stimulated compared with the fellow eyes. The response induced by the stimulation of the affected eye was decreased, even when the patient's visual acuity improved to 20/20 in the recovery phase. There was no difference in the concentration changes between the two eyes in the control subjects. NIRS may be useful in detecting visual dysfunction objectively and noninvasively in patients with visual disturbance, especially when used at the bedside.

High-frequency Ultrasound Imaging of Mouse Cervical Lymph Nodes.

PubMed

Walk, Elyse L; McLaughlin, Sarah L; Weed, Scott A

2015-07-25

High-frequency ultrasound (HFUS) is widely employed as a non-invasive method for imaging internal anatomic structures in experimental small animal systems. HFUS has the ability to detect structures as small as 30 µm, a property that has been utilized for visualizing superficial lymph nodes in rodents in brightness (B)-mode. Combining power Doppler with B-mode imaging allows for measuring circulatory blood flow within lymph nodes and other organs. While HFUS has been utilized for lymph node imaging in a number of mouse  model systems, a detailed protocol describing HFUS imaging and characterization of the cervical lymph nodes in mice has not been reported. Here, we show that HFUS can be adapted to detect and characterize cervical lymph nodes in mice. Combined B-mode and power Doppler imaging can be used to detect increases in blood flow in immunologically-enlarged cervical nodes. We also describe the use of B-mode imaging to conduct fine needle biopsies of cervical lymph nodes to retrieve lymph tissue for histological  analysis. Finally, software-aided steps are described to calculate changes in lymph node volume and to visualize changes in lymph node morphology following image reconstruction. The ability to visually monitor changes in cervical lymph node biology over time provides a simple and powerful technique for the non-invasive monitoring of cervical lymph node alterations in preclinical mouse models of oral cavity disease.

Semi-quantitative visual detection of loop mediated isothermal amplification (LAMP)-generated DNA by distance-based measurement on a paper device.

PubMed

Hongwarittorrn, Irin; Chaichanawongsaroj, Nuntaree; Laiwattanapaisal, Wanida

2017-12-01

A distance-based paper analytical device (dPAD) for loop mediated isothermal amplification (LAMP) detection based on distance measurement was proposed. This approach relied on visual detection by the length of colour developed on the dPAD with reference to semi-quantitative determination of the initial amount of genomic DNA. In this communication, E. coli DNA was chosen as a template DNA for LAMP reaction. In accordance with the principle, the dPAD was immobilized by polyethylenimine (PEI), which is a strong cationic polymer, in the hydrophilic channel of the paper device. Hydroxynaphthol blue (HNB), a colourimetric indicator for monitoring the change of magnesium ion concentration in the LAMP reaction, was used to react with the immobilized PEI. The positive charges of PEI react with the negative charges of free HNB in the LAMP reaction, producing a blue colour deposit on the paper device. Consequently, the apparently visual distance appeared within 5min and length of distance correlated to the amount of DNA in the sample. The distance-based PAD for the visual detection of the LAMP reaction could quantify the initial concentration of genomic DNA as low as 4.14 × 10 3 copiesµL -1 . This distance-based visual semi-quantitative platform is suitable for choice of LAMP detection method, particular in resource-limited settings because of the advantages of low cost, simple fabrication and operation, disposability and portable detection of the dPAD device. Copyright © 2017 Elsevier B.V. All rights reserved.

Temporal and Spatial Predictability of an Irrelevant Event Differently Affect Detection and Memory of Items in a Visual Sequence

PubMed Central

Ohyama, Junji; Watanabe, Katsumi

2016-01-01

We examined how the temporal and spatial predictability of a task-irrelevant visual event affects the detection and memory of a visual item embedded in a continuously changing sequence. Participants observed 11 sequentially presented letters, during which a task-irrelevant visual event was either present or absent. Predictabilities of spatial location and temporal position of the event were controlled in 2 × 2 conditions. In the spatially predictable conditions, the event occurred at the same location within the stimulus sequence or at another location, while, in the spatially unpredictable conditions, it occurred at random locations. In the temporally predictable conditions, the event timing was fixed relative to the order of the letters, while in the temporally unpredictable condition; it could not be predicted from the letter order. Participants performed a working memory task and a target detection reaction time (RT) task. Memory accuracy was higher for a letter simultaneously presented at the same location as the event in the temporally unpredictable conditions, irrespective of the spatial predictability of the event. On the other hand, the detection RTs were only faster for a letter simultaneously presented at the same location as the event when the event was both temporally and spatially predictable. Thus, to facilitate ongoing detection processes, an event must be predictable both in space and time, while memory processes are enhanced by temporally unpredictable (i.e., surprising) events. Evidently, temporal predictability has differential effects on detection and memory of a visual item embedded in a sequence of images. PMID:26869966

Temporal and Spatial Predictability of an Irrelevant Event Differently Affect Detection and Memory of Items in a Visual Sequence.

PubMed

Ohyama, Junji; Watanabe, Katsumi

2016-01-01

We examined how the temporal and spatial predictability of a task-irrelevant visual event affects the detection and memory of a visual item embedded in a continuously changing sequence. Participants observed 11 sequentially presented letters, during which a task-irrelevant visual event was either present or absent. Predictabilities of spatial location and temporal position of the event were controlled in 2 × 2 conditions. In the spatially predictable conditions, the event occurred at the same location within the stimulus sequence or at another location, while, in the spatially unpredictable conditions, it occurred at random locations. In the temporally predictable conditions, the event timing was fixed relative to the order of the letters, while in the temporally unpredictable condition; it could not be predicted from the letter order. Participants performed a working memory task and a target detection reaction time (RT) task. Memory accuracy was higher for a letter simultaneously presented at the same location as the event in the temporally unpredictable conditions, irrespective of the spatial predictability of the event. On the other hand, the detection RTs were only faster for a letter simultaneously presented at the same location as the event when the event was both temporally and spatially predictable. Thus, to facilitate ongoing detection processes, an event must be predictable both in space and time, while memory processes are enhanced by temporally unpredictable (i.e., surprising) events. Evidently, temporal predictability has differential effects on detection and memory of a visual item embedded in a sequence of images.

Fluid leak indicator

NASA Technical Reports Server (NTRS)

Anderson, G. E.; Loo, S. (Inventor)

1985-01-01

A fluid leak indicator for detecting and indicating leaks in visually inaccessible fluid tubing joints, such as those obstructed by insulation includes a bag system and a wicking system surrounding or wrapping the joints under the visual obstructing material. Leaking fluid is collected in the bag or on the wicking material where it is conducted along the wicking material to a visily accessible capturing transparent indicator bulb for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb.

Applying the metro map to software development management

NASA Astrophysics Data System (ADS)

Aguirregoitia, Amaia; Dolado, J. Javier; Presedo, Concepción

2010-01-01

This paper presents MetroMap, a new graphical representation model for controlling and managing the software development process. Metromap uses metaphors and visual representation techniques to explore several key indicators in order to support problem detection and resolution. The resulting visualization addresses diverse management tasks, such as tracking of deviations from the plan, analysis of patterns of failure detection and correction, overall assessment of change management policies, and estimation of product quality. The proposed visualization uses a metaphor with a metro map along with various interactive techniques to represent information concerning the software development process and to deal efficiently with multivariate visual queries. Finally, the paper shows the implementation of the tool in JavaFX with data of a real project and the results of testing the tool with the aforementioned data and users attempting several information retrieval tasks. The conclusion shows the results of analyzing user response time and efficiency using the MetroMap visualization system. The utility of the tool was positively evaluated.

The Benefit of Surface Uniformity for Encoding Boundary Features in Visual Working Memory

ERIC Educational Resources Information Center

Kim, Sung-Ho; Kim, Jung-Oh

2011-01-01

Using a change detection paradigm, the present study examined an object-based encoding benefit in visual working memory (VWM) for two boundary features (two orientations in Experiments 1-2 and two shapes in Experiments 3-4) assigned to a single object. Participants remembered more boundary features when they were conjoined into a single object of…

The reliability and stability of visual working memory capacity.

PubMed

Xu, Z; Adam, K C S; Fang, X; Vogel, E K

2018-04-01

Because of the central role of working memory capacity in cognition, many studies have used short measures of working memory capacity to examine its relationship to other domains. Here, we measured the reliability and stability of visual working memory capacity, measured using a single-probe change detection task. In Experiment 1, the participants (N = 135) completed a large number of trials of a change detection task (540 in total, 180 each of set sizes 4, 6, and 8). With large numbers of both trials and participants, reliability estimates were high (α > .9). We then used an iterative down-sampling procedure to create a look-up table for expected reliability in experiments with small sample sizes. In Experiment 2, the participants (N = 79) completed 31 sessions of single-probe change detection. The first 30 sessions took place over 30 consecutive days, and the last session took place 30 days later. This unprecedented number of sessions allowed us to examine the effects of practice on stability and internal reliability. Even after much practice, individual differences were stable over time (average between-session r = .76).

Estimated capacity of object files in visual short-term memory is not improved by retrieval cueing.

PubMed

Saiki, Jun; Miyatsuji, Hirofumi

2009-03-23

Visual short-term memory (VSTM) has been claimed to maintain three to five feature-bound object representations. Some results showing smaller capacity estimates for feature binding memory have been interpreted as the effects of interference in memory retrieval. However, change-detection tasks may not properly evaluate complex feature-bound representations such as triple conjunctions in VSTM. To understand the general type of feature-bound object representation, evaluation of triple conjunctions is critical. To test whether interference occurs in memory retrieval for complete object file representations in a VSTM task, we cued retrieval in novel paradigms that directly evaluate the memory for triple conjunctions, in comparison with a simple change-detection task. In our multiple object permanence tracking displays, observers monitored for a switch in feature combination between objects during an occlusion period, and we found that a retrieval cue provided no benefit with the triple conjunction tasks, but significant facilitation with the change-detection task, suggesting that low capacity estimates of object file memory in VSTM reflect a limit on maintenance, not retrieval.

Optical temperature sensor using thermochromic semiconductors

DOEpatents

Kronberg, J.W.

1996-08-20

An optical temperature measuring device utilizes thermochromic semiconductors which vary in color in response to changes in temperature. The thermochromic material is sealed in a glass matrix which allows the temperature sensor to detect high temperatures without breakdown. Cuprous oxide and cadmium sulfide are among the semiconductor materials which provide the best results. The changes in color may be detected visually or by utilizing an optical fiber and an electrical sensing circuit. 7 figs.

Quantifying changes in lens biomechanical properties due to cold cataract with optical coherence elastography

NASA Astrophysics Data System (ADS)

Zhang, Hongqiu; Wu, Chen; Singh, Manmohan; Larin, Kirill V.

2018-02-01

Cataract is the most prevalent cause of visual impairment worldwide. Cataracts can be formed due to trauma, radiation, drug abuse, or low temperatures. Thus, early detection of cataract can be immensely helpful for preserving visual acuity by ensuring that the appropriate therapeutic procedures are performed at earlier stages of disease onset and progression. In this work, we utilized a phase-sensitive optical coherence elastography (OCE) system to quantify changes in biomechanical properties of porcine lenses in vitro with induced cold cataracts. The results show significant increase in lens Young's modulus due to formation of the cold cataract (from 35 kPa to 60 kPa). These results show that OCE can assess lenticular biomechanical properties and may be useful for detecting and, potentially, characterizing cataracts.

Detecting and reacting to change: the effect of exposure to narrow categorizations.

PubMed

Chakravarti, Amitav; Fang, Christina; Shapira, Zur

2011-11-01

The ability to detect a change, to accurately assess the magnitude of the change, and to react to that change in a commensurate fashion are of critical importance in many decision domains. Thus, it is important to understand the factors that systematically affect people's reactions to change. In this article we document a novel effect: decision makers' reactions to a change (e.g., a visual change, a technology change) were systematically affected by the type of categorizations they encountered in an unrelated prior task (e.g., the response categories associated with a survey question). We found that prior exposure to narrow, as opposed to broad, categorizations improved decision makers' ability to detect change and led to stronger reactions to a given change. These differential reactions occurred because the prior categorizations, even though unrelated, altered the extent to which the subsequently presented change was perceived as either a relatively large change or a relatively small one.

Aerial estimation of the size of gull breeding colonies

USGS Publications Warehouse

Kadlec, J.A.; Drury, W.H.

1968-01-01

Counts on photographs and visual estimates of the numbers of territorial gulls are usually reliable indicators of the number of gull nests, but single visual estimates are not adequate to measure the number of nests in individual colonies. To properly interpret gull counts requires that several islands with known numbers of nests be photographed to establish the ratio of gulls to nests applicable for a given local census. Visual estimates are adequate to determine total breeding gull numbers by regions. Neither visual estimates nor photography will reliably detect annual changes of less than about 2.5 percent.

Audiovisual Rehabilitation in Hemianopia: A Model-Based Theoretical Investigation

PubMed Central

Magosso, Elisa; Cuppini, Cristiano; Bertini, Caterina

2017-01-01

Hemianopic patients exhibit visual detection improvement in the blind field when audiovisual stimuli are given in spatiotemporally coincidence. Beyond this “online” multisensory improvement, there is evidence of long-lasting, “offline” effects induced by audiovisual training: patients show improved visual detection and orientation after they were trained to detect and saccade toward visual targets given in spatiotemporal proximity with auditory stimuli. These effects are ascribed to the Superior Colliculus (SC), which is spared in these patients and plays a pivotal role in audiovisual integration and oculomotor behavior. Recently, we developed a neural network model of audiovisual cortico-collicular loops, including interconnected areas representing the retina, striate and extrastriate visual cortices, auditory cortex, and SC. The network simulated unilateral V1 lesion with possible spared tissue and reproduced “online” effects. Here, we extend the previous network to shed light on circuits, plastic mechanisms, and synaptic reorganization that can mediate the training effects and functionally implement visual rehabilitation. The network is enriched by the oculomotor SC-brainstem route, and Hebbian mechanisms of synaptic plasticity, and is used to test different training paradigms (audiovisual/visual stimulation in eye-movements/fixed-eyes condition) on simulated patients. Results predict different training effects and associate them to synaptic changes in specific circuits. Thanks to the SC multisensory enhancement, the audiovisual training is able to effectively strengthen the retina-SC route, which in turn can foster reinforcement of the SC-brainstem route (this occurs only in eye-movements condition) and reinforcement of the SC-extrastriate route (this occurs in presence of survived V1 tissue, regardless of eye condition). The retina-SC-brainstem circuit may mediate compensatory effects: the model assumes that reinforcement of this circuit can translate visual stimuli into short-latency saccades, possibly moving the stimuli into visual detection regions. The retina-SC-extrastriate circuit is related to restitutive effects: visual stimuli can directly elicit visual detection with no need for eye movements. Model predictions and assumptions are critically discussed in view of existing behavioral and neurophysiological data, forecasting that other oculomotor compensatory mechanisms, beyond short-latency saccades, are likely involved, and stimulating future experimental and theoretical investigations. PMID:29326578

Audiovisual Rehabilitation in Hemianopia: A Model-Based Theoretical Investigation.

PubMed

Magosso, Elisa; Cuppini, Cristiano; Bertini, Caterina

2017-01-01

Hemianopic patients exhibit visual detection improvement in the blind field when audiovisual stimuli are given in spatiotemporally coincidence. Beyond this "online" multisensory improvement, there is evidence of long-lasting, "offline" effects induced by audiovisual training: patients show improved visual detection and orientation after they were trained to detect and saccade toward visual targets given in spatiotemporal proximity with auditory stimuli. These effects are ascribed to the Superior Colliculus (SC), which is spared in these patients and plays a pivotal role in audiovisual integration and oculomotor behavior. Recently, we developed a neural network model of audiovisual cortico-collicular loops, including interconnected areas representing the retina, striate and extrastriate visual cortices, auditory cortex, and SC. The network simulated unilateral V1 lesion with possible spared tissue and reproduced "online" effects. Here, we extend the previous network to shed light on circuits, plastic mechanisms, and synaptic reorganization that can mediate the training effects and functionally implement visual rehabilitation. The network is enriched by the oculomotor SC-brainstem route, and Hebbian mechanisms of synaptic plasticity, and is used to test different training paradigms (audiovisual/visual stimulation in eye-movements/fixed-eyes condition) on simulated patients. Results predict different training effects and associate them to synaptic changes in specific circuits. Thanks to the SC multisensory enhancement, the audiovisual training is able to effectively strengthen the retina-SC route, which in turn can foster reinforcement of the SC-brainstem route (this occurs only in eye-movements condition) and reinforcement of the SC-extrastriate route (this occurs in presence of survived V1 tissue, regardless of eye condition). The retina-SC-brainstem circuit may mediate compensatory effects: the model assumes that reinforcement of this circuit can translate visual stimuli into short-latency saccades, possibly moving the stimuli into visual detection regions. The retina-SC-extrastriate circuit is related to restitutive effects: visual stimuli can directly elicit visual detection with no need for eye movements. Model predictions and assumptions are critically discussed in view of existing behavioral and neurophysiological data, forecasting that other oculomotor compensatory mechanisms, beyond short-latency saccades, are likely involved, and stimulating future experimental and theoretical investigations.

Change Detection Algorithms for Surveillance in Visual IoT: A Comparative Study

NASA Astrophysics Data System (ADS)

Akram, Beenish Ayesha; Zafar, Amna; Akbar, Ali Hammad; Wajid, Bilal; Chaudhry, Shafique Ahmad

2018-01-01

The VIoT (Visual Internet of Things) connects virtual information world with real world objects using sensors and pervasive computing. For video surveillance in VIoT, ChD (Change Detection) is a critical component. ChD algorithms identify regions of change in multiple images of the same scene recorded at different time intervals for video surveillance. This paper presents performance comparison of histogram thresholding and classification ChD algorithms using quantitative measures for video surveillance in VIoT based on salient features of datasets. The thresholding algorithms Otsu, Kapur, Rosin and classification methods k-means, EM (Expectation Maximization) were simulated in MATLAB using diverse datasets. For performance evaluation, the quantitative measures used include OSR (Overall Success Rate), YC (Yule's Coefficient) and JC (Jaccard's Coefficient), execution time and memory consumption. Experimental results showed that Kapur's algorithm performed better for both indoor and outdoor environments with illumination changes, shadowing and medium to fast moving objects. However, it reflected degraded performance for small object size with minor changes. Otsu algorithm showed better results for indoor environments with slow to medium changes and nomadic object mobility. k-means showed good results in indoor environment with small object size producing slow change, no shadowing and scarce illumination changes.

Eccentricity mapping of the human visual cortex to evaluate temporal dynamics of functional T1ρ mapping.

PubMed

Heo, Hye-Young; Wemmie, John A; Johnson, Casey P; Thedens, Daniel R; Magnotta, Vincent A

2015-07-01

Recent experiments suggest that T1 relaxation in the rotating frame (T(1ρ)) is sensitive to metabolism and can detect localized activity-dependent changes in the human visual cortex. Current functional magnetic resonance imaging (fMRI) methods have poor temporal resolution due to delays in the hemodynamic response resulting from neurovascular coupling. Because T(1ρ) is sensitive to factors that can be derived from tissue metabolism, such as pH and glucose concentration via proton exchange, we hypothesized that activity-evoked T(1ρ) changes in visual cortex may occur before the hemodynamic response measured by blood oxygenation level-dependent (BOLD) and arterial spin labeling (ASL) contrast. To test this hypothesis, functional imaging was performed using T(1ρ), BOLD, and ASL in human participants viewing an expanding ring stimulus. We calculated eccentricity phase maps across the occipital cortex for each functional signal and compared the temporal dynamics of T(1ρ) versus BOLD and ASL. The results suggest that T(1ρ) changes precede changes in the two blood flow-dependent measures. These observations indicate that T(1ρ) detects a signal distinct from traditional fMRI contrast methods. In addition, these findings support previous evidence that T(1ρ) is sensitive to factors other than blood flow, volume, or oxygenation. Furthermore, they suggest that tissue metabolism may be driving activity-evoked T(1ρ) changes.

Task demands determine comparison strategy in whole probe change detection.

PubMed

Udale, Rob; Farrell, Simon; Kent, Chris

2018-05-01

Detecting a change in our visual world requires a process that compares the external environment (test display) with the contents of memory (study display). We addressed the question of whether people strategically adapt the comparison process in response to different decision loads. Study displays of 3 colored items were presented, followed by 'whole-display' probes containing 3 colored shapes. Participants were asked to decide whether any probed items contained a new feature. In Experiments 1-4, irrelevant changes to the probed item's locations or feature bindings influenced memory performance, suggesting that participants employed a comparison process that relied on spatial locations. This finding occurred irrespective of whether participants were asked to decide about the whole display, or only a single cued item within the display. In Experiment 5, when the base-rate of changes in the nonprobed items increased (increasing the incentive to use the cue effectively), participants were not influenced by irrelevant changes in location or feature bindings. In addition, we observed individual differences in the use of spatial cues. These results suggest that participants can flexibly switch between spatial and nonspatial comparison strategies, depending on interactions between individual differences and task demand factors. These findings have implications for models of visual working memory that assume that the comparison between study and test obligatorily relies on accessing visual features via their binding to location. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Visual Distractors Disrupt Audiovisual Integration Regardless of Stimulus Complexity

PubMed Central

Gibney, Kyla D.; Aligbe, Enimielen; Eggleston, Brady A.; Nunes, Sarah R.; Kerkhoff, Willa G.; Dean, Cassandra L.; Kwakye, Leslie D.

2017-01-01

The intricate relationship between multisensory integration and attention has been extensively researched in the multisensory field; however, the necessity of attention for the binding of multisensory stimuli remains contested. In the current study, we investigated whether diverting attention from well-known multisensory tasks would disrupt integration and whether the complexity of the stimulus and task modulated this interaction. A secondary objective of this study was to investigate individual differences in the interaction of attention and multisensory integration. Participants completed a simple audiovisual speeded detection task and McGurk task under various perceptual load conditions: no load (multisensory task while visual distractors present), low load (multisensory task while detecting the presence of a yellow letter in the visual distractors), and high load (multisensory task while detecting the presence of a number in the visual distractors). Consistent with prior studies, we found that increased perceptual load led to decreased reports of the McGurk illusion, thus confirming the necessity of attention for the integration of speech stimuli. Although increased perceptual load led to longer response times for all stimuli in the speeded detection task, participants responded faster on multisensory trials than unisensory trials. However, the increase in multisensory response times violated the race model for no and low perceptual load conditions only. Additionally, a geometric measure of Miller’s inequality showed a decrease in multisensory integration for the speeded detection task with increasing perceptual load. Surprisingly, we found diverging changes in multisensory integration with increasing load for participants who did not show integration for the no load condition: no changes in integration for the McGurk task with increasing load but increases in integration for the detection task. The results of this study indicate that attention plays a crucial role in multisensory integration for both highly complex and simple multisensory tasks and that attention may interact differently with multisensory processing in individuals who do not strongly integrate multisensory information. PMID:28163675

Visual Distractors Disrupt Audiovisual Integration Regardless of Stimulus Complexity.

PubMed

Gibney, Kyla D; Aligbe, Enimielen; Eggleston, Brady A; Nunes, Sarah R; Kerkhoff, Willa G; Dean, Cassandra L; Kwakye, Leslie D

2017-01-01

The intricate relationship between multisensory integration and attention has been extensively researched in the multisensory field; however, the necessity of attention for the binding of multisensory stimuli remains contested. In the current study, we investigated whether diverting attention from well-known multisensory tasks would disrupt integration and whether the complexity of the stimulus and task modulated this interaction. A secondary objective of this study was to investigate individual differences in the interaction of attention and multisensory integration. Participants completed a simple audiovisual speeded detection task and McGurk task under various perceptual load conditions: no load (multisensory task while visual distractors present), low load (multisensory task while detecting the presence of a yellow letter in the visual distractors), and high load (multisensory task while detecting the presence of a number in the visual distractors). Consistent with prior studies, we found that increased perceptual load led to decreased reports of the McGurk illusion, thus confirming the necessity of attention for the integration of speech stimuli. Although increased perceptual load led to longer response times for all stimuli in the speeded detection task, participants responded faster on multisensory trials than unisensory trials. However, the increase in multisensory response times violated the race model for no and low perceptual load conditions only. Additionally, a geometric measure of Miller's inequality showed a decrease in multisensory integration for the speeded detection task with increasing perceptual load. Surprisingly, we found diverging changes in multisensory integration with increasing load for participants who did not show integration for the no load condition: no changes in integration for the McGurk task with increasing load but increases in integration for the detection task. The results of this study indicate that attention plays a crucial role in multisensory integration for both highly complex and simple multisensory tasks and that attention may interact differently with multisensory processing in individuals who do not strongly integrate multisensory information.

Visual Search Elicits the Electrophysiological Marker of Visual Working Memory

PubMed Central

Emrich, Stephen M.; Al-Aidroos, Naseem; Pratt, Jay; Ferber, Susanne

2009-01-01

Background Although limited in capacity, visual working memory (VWM) plays an important role in many aspects of visually-guided behavior. Recent experiments have demonstrated an electrophysiological marker of VWM encoding and maintenance, the contralateral delay activity (CDA), which has been shown in multiple tasks that have both explicit and implicit memory demands. Here, we investigate whether the CDA is evident during visual search, a thoroughly-researched task that is a hallmark of visual attention but has no explicit memory requirements. Methodology/Principal Findings The results demonstrate that the CDA is present during a lateralized search task, and that it is similar in amplitude to the CDA observed in a change-detection task, but peaks slightly later. The changes in CDA amplitude during search were strongly correlated with VWM capacity, as well as with search efficiency. These results were paralleled by behavioral findings showing a strong correlation between VWM capacity and search efficiency. Conclusions/Significance We conclude that the activity observed during visual search was generated by the same neural resources that subserve VWM, and that this activity reflects the maintenance of previously searched distractors. PMID:19956663

The effect of pit and fissure sealants on the detection of occlusal caries in vitro.

PubMed

Manton, D J; Messer, L B

2007-03-01

To compare, in vitro, the effect of placing opaque (OPS) and clear fluorescing (CFS) pit and fissure sealants (PFS) on the detection of occlusal caries (OCD). Occlusal surfaces of 67 extracted molars were examined under standardised conditions by 6 final year undergraduate dental students, using visual, bitewing radiography, transillumination (FOTI), laser fluorescence (LF) and tactile methods of caries detection. The teeth were then assigned randomly to two groups for PFS placement: OPS and CFS; then the OCD methods were repeated. Caries presence/absence was determined histologically on serial sections examined under stereo-microscopy (10x). Before PFS placement the sensitivity and specificity for the OCD methods were: visual: 68%, 71%; radiographic: 15%, 95%; FOTI: 36%, 93%; LF: 49%, 83% and tactile: 39%, 67%, respectively. After placement of OPS, the sensitivity of LF (20%) and visual (13%) methods decreased and specificity increased (93%, 98% respectively). Placement of CFS resulted in minor changes in sensitivity and specificity. Correlation (Spearman's Rho coefficients) between OCD methods and histological intra-dentinal caries for pre- PFS, OPS, and CFS were: visual: 0.38, 0.34, 0.33; FOTI: 0.42, 0.35, 0.43; and LF: 0.41, 0.30, and 0.45 respectively. The sensitivity of all OCD methods was low, as well as their correlation to the histological gold standard. Placing OPS further decreased the sensitivity of LF and visual methods, whereas placing CFS had little effect on all OCD methods. It is recommended that tactile detection of occlusal caries should be discontinued, and the probe used only to clean the pits and fissures gently for more accurate visual detection, or prior to pit and fissure sealant placement. Further research into the development of an affordable, robust, accurate and easy to use method for OCD is required.

High visual working memory capacity in trait social anxiety.

PubMed

Moriya, Jun; Sugiura, Yoshinori

2012-01-01

Working memory capacity is one of the most important cognitive functions influencing individual traits, such as attentional control, fluid intelligence, and also psychopathological traits. Previous research suggests that anxiety is associated with impaired cognitive function, and studies have shown low verbal working memory capacity in individuals with high trait anxiety. However, the relationship between trait anxiety and visual working memory capacity is still unclear. Considering that people allocate visual attention more widely to detect danger under threat, visual working memory capacity might be higher in anxious people. In the present study, we show that visual working memory capacity increases as trait social anxiety increases by using a change detection task. When the demand to inhibit distractors increased, however, high visual working memory capacity diminished in individuals with social anxiety, and instead, impaired filtering of distractors was predicted by trait social anxiety. State anxiety was not correlated with visual working memory capacity. These results indicate that socially anxious people could potentially hold a large amount of information in working memory. However, because of an impaired cognitive function, they could not inhibit goal-irrelevant distractors and their performance decreased under highly demanding conditions.

A new metric for detecting change in slowly evolving brain tumors: validation in meningioma patients.

PubMed

Pohl, Kilian M; Konukoglu, Ender; Novellas, Sebastian; Ayache, Nicholas; Fedorov, Andriy; Talos, Ion-Florin; Golby, Alexandra; Wells, William M; Kikinis, Ron; Black, Peter M

2011-03-01

Change detection is a critical component in the diagnosis and monitoring of many slowly evolving pathologies. This article describes a semiautomatic monitoring approach using longitudinal medical images. We test the method on brain scans of patients with meningioma, which experts have found difficult to monitor because the tumor evolution is very slow and may be obscured by artifacts related to image acquisition. We describe a semiautomatic procedure targeted toward identifying difficult-to-detect changes in brain tumor imaging. The tool combines input from a medical expert with state-of-the-art technology. The software is easy to calibrate and, in less than 5 minutes, returns the total volume of tumor change in mm. We test the method on postgadolinium, T1-weighted magnetic resonance images of 10 patients with meningioma and compare our results with experts' findings. We also perform benchmark testing with synthetic data. Our experiments indicated that experts' visual inspections are not sensitive enough to detect subtle growth. Measurements based on experts' manual segmentations were highly accurate but also labor intensive. The accuracy of our approach was comparable to the experts' results. However, our approach required far less user input and generated more consistent measurements. The sensitivity of experts' visual inspection is often too low to detect subtle growth of meningiomas from longitudinal scans. Measurements based on experts' segmentation are highly accurate but generally too labor intensive for standard clinical settings. We described an alternative metric that provides accurate and robust measurements of subtle tumor changes while requiring a minimal amount of user input.

Netgram: Visualizing Communities in Evolving Networks

PubMed Central

Mall, Raghvendra; Langone, Rocco; Suykens, Johan A. K.

2015-01-01

Real-world complex networks are dynamic in nature and change over time. The change is usually observed in the interactions within the network over time. Complex networks exhibit community like structures. A key feature of the dynamics of complex networks is the evolution of communities over time. Several methods have been proposed to detect and track the evolution of these groups over time. However, there is no generic tool which visualizes all the aspects of group evolution in dynamic networks including birth, death, splitting, merging, expansion, shrinkage and continuation of groups. In this paper, we propose Netgram: a tool for visualizing evolution of communities in time-evolving graphs. Netgram maintains evolution of communities over 2 consecutive time-stamps in tables which are used to create a query database using the sql outer-join operation. It uses a line-based visualization technique which adheres to certain design principles and aesthetic guidelines. Netgram uses a greedy solution to order the initial community information provided by the evolutionary clustering technique such that we have fewer line cross-overs in the visualization. This makes it easier to track the progress of individual communities in time evolving graphs. Netgram is a generic toolkit which can be used with any evolutionary community detection algorithm as illustrated in our experiments. We use Netgram for visualization of topic evolution in the NIPS conference over a period of 11 years and observe the emergence and merging of several disciplines in the field of information processing systems. PMID:26356538

Multichannel optical mapping: investigation of depth information

NASA Astrophysics Data System (ADS)

Sase, Ichiro; Eda, Hideo; Seiyama, Akitoshi; Tanabe, Hiroki C.; Takatsuki, Akira; Yanagida, Toshio

2001-06-01

Near infrared (NIR) light has become a powerful tool for non-invasive imaging of human brain activity. Many systems have been developed to capture the changes in regional brain blood flow and hemoglobin oxygenation, which occur in the human cortex in response to neural activity. We have developed a multi-channel reflectance imaging system, which can be used as a `mapping device' and also as a `multi-channel spectrophotometer'. In the present study, we visualized changes in the hemodynamics of the human occipital region in multiple ways. (1) Stimulating left and right primary visual cortex independently by showing sector shaped checkerboards sequentially over the contralateral visual field, resulted in corresponding changes in the hemodynamics observed by `mapping' measurement. (2) Simultaneous measurement of functional-MRI and NIR (changes in total hemoglobin) during visual stimulation showed good spatial and temporal correlation with each other. (3) Placing multiple channels densely over the occipital region demonstrated spatial patterns more precisely, and depth information was also acquired by placing each pair of illumination and detection fibers at various distances. These results indicate that optical method can provide data for 3D analysis of human brain functions.

Helicopter pilot estimation of self-altitude in a degraded visual environment

NASA Astrophysics Data System (ADS)

Crowley, John S.; Haworth, Loran A.; Szoboszlay, Zoltan P.; Lee, Alan G.

2000-06-01

The effect of night vision devices and degraded visual imagery on self-attitude perception is unknown. Thirteen Army aviators with normal vision flew five flights under various visual conditions in a modified AH-1 (Cobra) helicopter. Subjects estimated their altitude or flew to specified altitudes while flying a series of maneuvers. The results showed that subjects were better at detecting and controlling changes in altitude than they were at flying to or naming a specific altitude. In cruise flight and descent, the subjects tended to fly above the desired altitude, an error in the safe direction. While hovering, the direction of error was less predictable. In the low-level cruise flight scenario tested in this study, altitude perception was affected more by changes in image resolution than by changes in FOV or ocularity.

Selection for Social Signalling Drives the Evolution of Chameleon Colour Change

PubMed Central

Stuart-Fox, Devi; Moussalli, Adnan

2008-01-01

Rapid colour change is a remarkable natural phenomenon that has evolved in several vertebrate and invertebrate lineages. The two principal explanations for the evolution of this adaptive strategy are (1) natural selection for crypsis (camouflage) against a range of different backgrounds and (2) selection for conspicuous social signals that maximise detectability to conspecifics, yet minimise exposure to predators because they are only briefly displayed. Here we show that evolutionary shifts in capacity for colour change in southern African dwarf chameleons (Bradypodion spp.) are associated with increasingly conspicuous signals used in male contests and courtship. To the chameleon visual system, species showing the most dramatic colour change display social signals that contrast most against the environmental background and amongst adjacent body regions. We found no evidence for the crypsis hypothesis, a finding reinforced by visual models of how both chameleons and their avian predators perceive chameleon colour variation. Instead, our results suggest that selection for conspicuous social signals drives the evolution of colour change in this system, supporting the view that transitory display traits should be under strong selection for signal detectability. PMID:18232740

Close similarity between spatiotemporal frequency tunings of human cortical responses and involuntary manual following responses to visual motion.

PubMed

Amano, Kaoru; Kimura, Toshitaka; Nishida, Shin'ya; Takeda, Tsunehiro; Gomi, Hiroaki

2009-02-01

Human brain uses visual motion inputs not only for generating subjective sensation of motion but also for directly guiding involuntary actions. For instance, during arm reaching, a large-field visual motion is quickly and involuntarily transformed into a manual response in the direction of visual motion (manual following response, MFR). Previous attempts to correlate motion-evoked cortical activities, revealed by brain imaging techniques, with conscious motion perception have resulted only in partial success. In contrast, here we show a surprising degree of similarity between the MFR and the population neural activity measured by magnetoencephalography (MEG). We measured the MFR and MEG induced by the same motion onset of a large-field sinusoidal drifting grating with changing the spatiotemporal frequency of the grating. The initial transient phase of these two responses had very similar spatiotemporal tunings. Specifically, both the MEG and MFR amplitudes increased as the spatial frequency was decreased to, at most, 0.05 c/deg, or as the temporal frequency was increased to, at least, 10 Hz. We also found in peak latency a quantitative agreement (approximately 100-150 ms) and correlated changes against spatiotemporal frequency changes between MEG and MFR. In comparison with these two responses, conscious visual motion detection is known to be most sensitive (i.e., have the lowest detection threshold) at higher spatial frequencies and have longer and more variable response latencies. Our results suggest a close relationship between the properties of involuntary motor responses and motion-evoked cortical activity as reflected by the MEG.

Reading performance after vision rehabilitation of subjects with homonymous visual field defects.

PubMed

Gall, Carolin; Sabel, Bernhard A

2012-12-01

To examine whether increased visual functioning after vision-restoration training (VRT) coincides with improved reading abilities. Prospective noncontrolled open-label trial. Controlled laboratory setting for all diagnostic procedures that were conducted before and after 6 months of home-based VRT with telemedicine support. Eleven subjects who had experienced a posterior-parietal stroke and have homonymous visual field defects. Six months of VRT (1 hour daily repeated light stimulation in the partially damaged visual field). VRT outcome measures were the number of detected light stimuli in eye-tracker controlled high-resolution perimetry and the spared visual field within the affected hemifield up to the relative and absolute defect visual field border (square degrees). Enlargements of spared visual field within the affected hemifield were correlated with changes of reading speed after VRT. After VRT, the number of detected light stimuli increased by 5.02 ± 4.31% (mean ± SD; P = .03). The spared visual field up to the relative defect visual field border increased from 18.09 ± 32.35 square degrees before to 137.40 ± 53.32 after VRT (P = .006), as well as for the absolute defect visual field border from 36.95 ± 33.77 square degrees before VRT to 152.02 ± 49.70 after VRT (P = .005). Reading speed increased from 108.95 ± 33.95 words per minute before VRT to 122.26 ± 30.35 after VRT (P = .017), which significantly correlated with increased spared visual field up to the relative defect visual field border (r = 0.73, P = .016). Measures of eye movement variability did not correlate with VRT outcome. VRT improved visual fields in parafoveal areas, which are most relevant for reading. This finding cannot be explained by changes in eye movement behavior. Because of a significant association between improvements of parafoveal vision and reading speed, we propose that patients with homonymous visual field defects who have reading deficits may benefit from visual stimulation by training. Copyright © 2012 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Natural history of drusenoid pigment epithelial detachment in age-related macular degeneration: Age-Related Eye Disease Study Report No. 28.

PubMed

Cukras, Catherine; Agrón, Elvira; Klein, Michael L; Ferris, Frederick L; Chew, Emily Y; Gensler, Gary; Wong, Wai T

2010-03-01

To describe the natural history of eyes with drusenoid pigment epithelial detachments (DPEDs) associated with age-related macular degeneration (AMD). Multicenter, clinic-based, prospective cohort study. Among 4757 participants enrolled in the Age-Related Eye Disease Study (AREDS), 255 were identified as having DPED in at least 1 eye and having 5 or more years of follow-up after the initial detection of the DPED. Baseline and annual fundus photographs were evaluated for the evolution of the fundus features and the development of advanced AMD in the forms of central geographic atrophy (CGA) or neovascular (NV) AMD. Kaplan-Meier analyses of progression to advanced AMD and of moderate vision loss (> or =15 letters compared with baseline) were performed. Rate of progression to advanced AMD and change in visual acuity from baseline (in terms of mean letters lost and proportion losing > or =15 letters). A total of 311 eyes (from 255 participants) with DPED were followed for a median follow-up time of 8 years subsequent to the initial detection of a DPED. Of the 282 eyes that did not have advanced AMD at baseline, advanced AMD developed within 5 years in 119 eyes (42%) (19% progressing to CGA and 23% progressing to NV-AMD). In the remaining eyes that did not develop advanced AMD (n=163), progressive fundus changes, typified by the development of calcified drusen and pigmentary changes, were detected. Visual decline was prominent among study eyes, with approximately 40% of all eyes decreasing in visual acuity by > or =15 letters at 5 years follow-up. Mean visual acuity decreased from 76 letters ( approximately 20/30) at baseline to 61 letters ( approximately 20/60) at 5 years. Five-year decreases in mean visual acuity averaged 26 letters for eyes progressing to advanced AMD and 8 letters for non-progressing eyes. The natural history of eyes containing DPED is characterized by a high rate of progression to both CGA and NV-AMD. Among eyes not progressing to advanced AMD, progressive development of pigmentary changes and calcified drusen were observed. Decline of visual acuity is a common outcome, with or without progression to advanced forms of AMD. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Eye Movements and Visual Memory for Scenes

DTIC Science & Technology

2005-01-01

Scene memory research has demonstrated that the memory representation of a semantically inconsistent object in a scene is more detailed and/or complete... memory during scene viewing, then changes to semantically inconsistent objects (which should be represented more com- pletely) should be detected more... semantic description. Due to the surprise nature of the visual memory test, any learning that occurred during the search portion of the experiment was

Cell-assembly coding in several memory processes.

PubMed

Sakurai, Y

1998-01-01

The present paper discusses why the cell assembly, i.e., an ensemble population of neurons with flexible functional connections, is a tenable view of the basic code for information processes in the brain. The main properties indicating the reality of cell-assembly coding are neurons overlaps among different assemblies and connection dynamics within and among the assemblies. The former can be detected as multiple functions of individual neurons in processing different kinds of information. Individual neurons appear to be involved in multiple information processes. The latter can be detected as changes of functional synaptic connections in processing different kinds of information. Correlations of activity among some of the recorded neurons appear to change in multiple information processes. Recent experiments have compared several different memory processes (tasks) and detected these two main properties, indicating cell-assembly coding of memory in the working brain. The first experiment compared different types of processing of identical stimuli, i.e., working memory and reference memory of auditory stimuli. The second experiment compared identical processes of different types of stimuli, i.e., discriminations of simple auditory, simple visual, and configural auditory-visual stimuli. The third experiment compared identical processes of different types of stimuli with or without temporal processing of stimuli, i.e., discriminations of elemental auditory, configural auditory-visual, and sequential auditory-visual stimuli. Some possible features of the cell-assembly coding, especially "dual coding" by individual neurons and cell assemblies, are discussed for future experimental approaches. Copyright 1998 Academic Press.

Molecular magnetic resonance imaging of atherosclerotic vessel wall disease.

PubMed

Nörenberg, Dominik; Ebersberger, Hans U; Diederichs, Gerd; Hamm, Bernd; Botnar, René M; Makowski, Marcus R

2016-03-01

Molecular imaging aims to improve the identification and characterization of pathological processes in vivo by visualizing the underlying biological mechanisms. Molecular imaging techniques are increasingly used to assess vascular inflammation, remodeling, cell migration, angioneogenesis and apoptosis. In cardiovascular diseases, molecular magnetic resonance imaging (MRI) offers new insights into the in vivo biology of pathological vessel wall processes of the coronary and carotid arteries and the aorta. This includes detection of early vascular changes preceding plaque development, visualization of unstable plaques and assessment of response to therapy. The current review focuses on recent developments in the field of molecular MRI to characterise different stages of atherosclerotic vessel wall disease. A variety of molecular MR-probes have been developed to improve the non-invasive detection and characterization of atherosclerotic plaques. Specifically targeted molecular probes allow for the visualization of key biological steps in the cascade leading to the development of arterial vessel wall lesions. Early detection of processes which lead to the development of atherosclerosis and the identification of vulnerable atherosclerotic plaques may enable the early assessment of response to therapy, improve therapy planning, foster the prevention of cardiovascular events and may open the door for the development of patient-specific treatment strategies. Targeted MR-probes allow the characterization of atherosclerosis on a molecular level. Molecular MRI can identify in vivo markers for the differentiation of stable and unstable plaques. Visualization of early molecular changes has the potential to improve patient-individualized risk-assessment.

Short-term memory stores organized by information domain.

PubMed

Noyce, Abigail L; Cestero, Nishmar; Shinn-Cunningham, Barbara G; Somers, David C

2016-04-01

Vision and audition have complementary affinities, with vision excelling in spatial resolution and audition excelling in temporal resolution. Here, we investigated the relationships among the visual and auditory modalities and spatial and temporal short-term memory (STM) using change detection tasks. We created short sequences of visual or auditory items, such that each item within a sequence arose at a unique spatial location at a unique time. On each trial, two successive sequences were presented; subjects attended to either space (the sequence of locations) or time (the sequence of inter item intervals) and reported whether the patterns of locations or intervals were identical. Each subject completed blocks of unimodal trials (both sequences presented in the same modality) and crossmodal trials (Sequence 1 visual, Sequence 2 auditory, or vice versa) for both spatial and temporal tasks. We found a strong interaction between modality and task: Spatial performance was best on unimodal visual trials, whereas temporal performance was best on unimodal auditory trials. The order of modalities on crossmodal trials also mattered, suggesting that perceptual fidelity at encoding is critical to STM. Critically, no cost was attributable to crossmodal comparison: In both tasks, performance on crossmodal trials was as good as or better than on the weaker unimodal trials. STM representations of space and time can guide change detection in either the visual or the auditory modality, suggesting that the temporal or spatial organization of STM may supersede sensory-specific organization.

A parallel spatiotemporal saliency and discriminative online learning method for visual target tracking in aerial videos.

PubMed

Aghamohammadi, Amirhossein; Ang, Mei Choo; A Sundararajan, Elankovan; Weng, Ng Kok; Mogharrebi, Marzieh; Banihashem, Seyed Yashar

2018-01-01

Visual tracking in aerial videos is a challenging task in computer vision and remote sensing technologies due to appearance variation difficulties. Appearance variations are caused by camera and target motion, low resolution noisy images, scale changes, and pose variations. Various approaches have been proposed to deal with appearance variation difficulties in aerial videos, and amongst these methods, the spatiotemporal saliency detection approach reported promising results in the context of moving target detection. However, it is not accurate for moving target detection when visual tracking is performed under appearance variations. In this study, a visual tracking method is proposed based on spatiotemporal saliency and discriminative online learning methods to deal with appearance variations difficulties. Temporal saliency is used to represent moving target regions, and it was extracted based on the frame difference with Sauvola local adaptive thresholding algorithms. The spatial saliency is used to represent the target appearance details in candidate moving regions. SLIC superpixel segmentation, color, and moment features can be used to compute feature uniqueness and spatial compactness of saliency measurements to detect spatial saliency. It is a time consuming process, which prompted the development of a parallel algorithm to optimize and distribute the saliency detection processes that are loaded into the multi-processors. Spatiotemporal saliency is then obtained by combining the temporal and spatial saliencies to represent moving targets. Finally, a discriminative online learning algorithm was applied to generate a sample model based on spatiotemporal saliency. This sample model is then incrementally updated to detect the target in appearance variation conditions. Experiments conducted on the VIVID dataset demonstrated that the proposed visual tracking method is effective and is computationally efficient compared to state-of-the-art methods.

A parallel spatiotemporal saliency and discriminative online learning method for visual target tracking in aerial videos

PubMed Central

2018-01-01

Visual tracking in aerial videos is a challenging task in computer vision and remote sensing technologies due to appearance variation difficulties. Appearance variations are caused by camera and target motion, low resolution noisy images, scale changes, and pose variations. Various approaches have been proposed to deal with appearance variation difficulties in aerial videos, and amongst these methods, the spatiotemporal saliency detection approach reported promising results in the context of moving target detection. However, it is not accurate for moving target detection when visual tracking is performed under appearance variations. In this study, a visual tracking method is proposed based on spatiotemporal saliency and discriminative online learning methods to deal with appearance variations difficulties. Temporal saliency is used to represent moving target regions, and it was extracted based on the frame difference with Sauvola local adaptive thresholding algorithms. The spatial saliency is used to represent the target appearance details in candidate moving regions. SLIC superpixel segmentation, color, and moment features can be used to compute feature uniqueness and spatial compactness of saliency measurements to detect spatial saliency. It is a time consuming process, which prompted the development of a parallel algorithm to optimize and distribute the saliency detection processes that are loaded into the multi-processors. Spatiotemporal saliency is then obtained by combining the temporal and spatial saliencies to represent moving targets. Finally, a discriminative online learning algorithm was applied to generate a sample model based on spatiotemporal saliency. This sample model is then incrementally updated to detect the target in appearance variation conditions. Experiments conducted on the VIVID dataset demonstrated that the proposed visual tracking method is effective and is computationally efficient compared to state-of-the-art methods. PMID:29438421

Motivation enhances visual working memory capacity through the modulation of central cognitive processes.

PubMed

Sanada, Motoyuki; Ikeda, Koki; Kimura, Kenta; Hasegawa, Toshikazu

2013-09-01

Motivation is well known to enhance working memory (WM) capacity, but the mechanism underlying this effect remains unclear. The WM process can be divided into encoding, maintenance, and retrieval, and in a change detection visual WM paradigm, the encoding and retrieval processes can be subdivided into perceptual and central processing. To clarify which of these segments are most influenced by motivation, we measured ERPs in a change detection task with differential monetary rewards. The results showed that the enhancement of WM capacity under high motivation was accompanied by modulations of late central components but not those reflecting attentional control on perceptual inputs across all stages of WM. We conclude that the "state-dependent" shift of motivation impacted the central, rather than the perceptual functions in order to achieve better behavioral performances. Copyright © 2013 Society for Psychophysiological Research.

Fluid leak indicator

NASA Technical Reports Server (NTRS)

Anderson, George E. (Inventor); Loo, Shu (Inventor)

1989-01-01

A fluid leak indicator (30) for detecting and indicating leaks in visually inaccessible fluid tubing joints (20, 21), such as those obstructed by insulation (24), includes a bag system (25) and a wicking system (30) surrounding or wrapping the joints (20, 21) under the visual obstructing material (24). Leaking fluid is collected in the bag (25) or on the wicking material (34) where it is conducted along the wicking material (34) to a visibly accessible capturing transparent indicator bulb (35) for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb (35).

Principal visual word discovery for automatic license plate detection.

PubMed

Zhou, Wengang; Li, Houqiang; Lu, Yijuan; Tian, Qi

2012-09-01

License plates detection is widely considered a solved problem, with many systems already in operation. However, the existing algorithms or systems work well only under some controlled conditions. There are still many challenges for license plate detection in an open environment, such as various observation angles, background clutter, scale changes, multiple plates, uneven illumination, and so on. In this paper, we propose a novel scheme to automatically locate license plates by principal visual word (PVW), discovery and local feature matching. Observing that characters in different license plates are duplicates of each other, we bring in the idea of using the bag-of-words (BoW) model popularly applied in partial-duplicate image search. Unlike the classic BoW model, for each plate character, we automatically discover the PVW characterized with geometric context. Given a new image, the license plates are extracted by matching local features with PVW. Besides license plate detection, our approach can also be extended to the detection of logos and trademarks. Due to the invariance virtue of scale-invariant feature transform feature, our method can adaptively deal with various changes in the license plates, such as rotation, scaling, illumination, etc. Promising results of the proposed approach are demonstrated with an experimental study in license plate detection.

The reliability and internal consistency of one-shot and flicker change detection for measuring individual differences in visual working memory capacity.

PubMed

Pailian, Hrag; Halberda, Justin

2015-04-01

We investigated the psychometric properties of the one-shot change detection task for estimating visual working memory (VWM) storage capacity-and also introduced and tested an alternative flicker change detection task for estimating these limits. In three experiments, we found that the one-shot whole-display task returns estimates of VWM storage capacity (K) that are unreliable across set sizes-suggesting that the whole-display task is measuring different things at different set sizes. In two additional experiments, we found that the one-shot single-probe variant shows improvements in the reliability and consistency of K estimates. In another additional experiment, we found that a one-shot whole-display-with-click task (requiring target localization) also showed improvements in reliability and consistency. The latter results suggest that the one-shot task can return reliable and consistent estimates of VWM storage capacity (K), and they highlight the possibility that the requirement to localize the changed target is what engenders this enhancement. Through a final series of four experiments, we introduced and tested an alternative flicker change detection method that also requires the observer to localize the changing target and that generates, from response times, an estimate of VWM storage capacity (K). We found that estimates of K from the flicker task correlated with estimates from the traditional one-shot task and also had high reliability and consistency. We highlight the flicker method's ability to estimate executive functions as well as VWM storage capacity, and discuss the potential for measuring multiple abilities with the one-shot and flicker tasks.

Rapid Processing of a Global Feature in the ON Visual Pathways of Behaving Monkeys.

PubMed

Huang, Jun; Yang, Yan; Zhou, Ke; Zhao, Xudong; Zhou, Quan; Zhu, Hong; Yang, Yingshan; Zhang, Chunming; Zhou, Yifeng; Zhou, Wu

2017-01-01

Visual objects are recognized by their features. Whereas, some features are based on simple components (i.e., local features, such as orientation of line segments), some features are based on the whole object (i.e., global features, such as an object having a hole in it). Over the past five decades, behavioral, physiological, anatomical, and computational studies have established a general model of vision, which starts from extracting local features in the lower visual pathways followed by a feature integration process that extracts global features in the higher visual pathways. This local-to-global model is successful in providing a unified account for a vast sets of perception experiments, but it fails to account for a set of experiments showing human visual systems' superior sensitivity to global features. Understanding the neural mechanisms underlying the "global-first" process will offer critical insights into new models of vision. The goal of the present study was to establish a non-human primate model of rapid processing of global features for elucidating the neural mechanisms underlying differential processing of global and local features. Monkeys were trained to make a saccade to a target in the black background, which was different from the distractors (white circle) in color (e.g., red circle target), local features (e.g., white square target), a global feature (e.g., white ring with a hole target) or their combinations (e.g., red square target). Contrary to the predictions of the prevailing local-to-global model, we found that (1) detecting a distinction or a change in the global feature was faster than detecting a distinction or a change in color or local features; (2) detecting a distinction in color was facilitated by a distinction in the global feature, but not in the local features; and (3) detecting the hole was interfered by the local features of the hole (e.g., white ring with a squared hole). These results suggest that monkey ON visual systems have a subsystem that is more sensitive to distinctions in the global feature than local features. They also provide the behavioral constraints for identifying the underlying neural substrates.

Visual search and emotion: how children with autism spectrum disorders scan emotional scenes.

PubMed

Maccari, Lisa; Pasini, Augusto; Caroli, Emanuela; Rosa, Caterina; Marotta, Andrea; Martella, Diana; Fuentes, Luis J; Casagrande, Maria

2014-11-01

This study assessed visual search abilities, tested through the flicker task, in children diagnosed with autism spectrum disorders (ASDs). Twenty-two children diagnosed with ASD and 22 matched typically developing (TD) children were told to detect changes in objects of central interest or objects of marginal interest (MI) embedded in either emotion-laden (positive or negative) or neutral real-world pictures. The results showed that emotion-laden pictures equally interfered with performance of both ASD and TD children, slowing down reaction times compared with neutral pictures. Children with ASD were faster than TD children, particularly in detecting changes in MI objects, the most difficult condition. However, their performance was less accurate than performance of TD children just when the pictures were negative. These findings suggest that children with ASD have better visual search abilities than TD children only when the search is particularly difficult and requires strong serial search strategies. The emotional-social impairment that is usually considered as a typical feature of ASD seems to be limited to processing of negative emotional information.

Cholinergic Modulation of Frontoparietal Cortical Network Dynamics Supporting Supramodal Attention.

PubMed

Ljubojevic, Vladimir; Luu, Paul; Gill, Patrick Robert; Beckett, Lee-Anne; Takehara-Nishiuchi, Kaori; De Rosa, Eve

2018-04-18

A critical function of attention is to support a state of readiness to enhance stimulus detection, independent of stimulus modality. The nucleus basalis magnocellularis (NBM) is the major source of the neurochemical acetylcholine (ACh) for frontoparietal cortical networks thought to support attention. We examined a potential supramodal role of ACh in a frontoparietal cortical attentional network supporting target detection. We recorded local field potentials (LFPs) in the prelimbic frontal cortex (PFC) and the posterior parietal cortex (PPC) to assess whether ACh contributed to a state of readiness to alert rats to an impending presentation of visual or olfactory targets in one of five locations. Twenty male Long-Evans rats underwent training and then lesions of the NBM using the selective cholinergic immunotoxin 192 IgG-saporin (0.3 μg/μl; ACh-NBM-lesion) to reduce cholinergic afferentation of the cortical mantle. Postsurgery, ACh-NBM-lesioned rats had less correct responses and more omissions than sham-lesioned rats, which changed parametrically as we increased the attentional demands of the task with decreased target duration. This parametric deficit was found equally for both sensory targets. Accurate detection of visual and olfactory targets was associated specifically with increased LFP coherence, in the beta range, between the PFC and PPC, and with increased beta power in the PPC before the target's appearance in sham-lesioned rats. Readiness-associated changes in brain activity and visual and olfactory target detection were attenuated in the ACh-NBM-lesioned group. Accordingly, ACh may support supramodal attention via modulating activity in a frontoparietal cortical network, orchestrating a state of readiness to enhance target detection. SIGNIFICANCE STATEMENT We examined whether the neurochemical acetylcholine (ACh) contributes to a state of readiness for target detection, by engaging frontoparietal cortical attentional networks independent of modality. We show that ACh supported alerting attention to an impending presentation of either visual or olfactory targets. Using local field potentials, enhanced stimulus detection was associated with an anticipatory increase in power in the beta oscillation range before the target's appearance within the posterior parietal cortex (PPC) as well as increased synchrony, also in beta, between the prefrontal cortex and PPC. These readiness-associated changes in brain activity and behavior were attenuated in rats with reduced cortical ACh. Thus, ACh may act, in a supramodal manner, to prepare frontoparietal cortical attentional networks for target detection. Copyright © 2018 the authors 0270-6474/18/383988-18$15.00/0.

Aversive learning shapes neuronal orientation tuning in human visual cortex.

PubMed

McTeague, Lisa M; Gruss, L Forest; Keil, Andreas

2015-07-28

The responses of sensory cortical neurons are shaped by experience. As a result perceptual biases evolve, selectively facilitating the detection and identification of sensory events that are relevant for adaptive behaviour. Here we examine the involvement of human visual cortex in the formation of learned perceptual biases. We use classical aversive conditioning to associate one out of a series of oriented gratings with a noxious sound stimulus. After as few as two grating-sound pairings, visual cortical responses to the sound-paired grating show selective amplification. Furthermore, as learning progresses, responses to the orientations with greatest similarity to the sound-paired grating are increasingly suppressed, suggesting inhibitory interactions between orientation-selective neuronal populations. Changes in cortical connectivity between occipital and fronto-temporal regions mirror the changes in visuo-cortical response amplitudes. These findings suggest that short-term behaviourally driven retuning of human visual cortical neurons involves distal top-down projections as well as local inhibitory interactions.

High sensitivity, loop-mediated isothermal amplification combined with colorimetric gold-nanoparticle probes for visual detection of high risk human papillomavirus genotypes 16 and 18.

PubMed

Kumvongpin, Ratchanida; Jearanaikool, Patcharee; Wilailuckana, Chotechana; Sae-Ung, Nattaya; Prasongdee, Prinya; Daduang, Sakda; Wongsena, Metee; Boonsiri, Patcharee; Kiatpathomchai, Wansika; Swangvaree, Sukumarn Sanersak; Sandee, Alisa; Daduang, Jureerut

2016-08-01

High-risk human papillomavirus (HR-HPV) causes cervical cancer. HPV16 and HPV18 are the most prevalent strains of the virus reported in women worldwide. Loop-mediated isothermal amplification (LAMP) is an alternative method for DNA detection under isothermal conditions. However, it results in a turbid amplified product which is not easily detected by the naked eye. This study aimed to develop an improved technique by using gold nanoparticles (AuNPs) attached to a single-stranded DNA probe for the detection of HPV16 and HPV18. Detection of the LAMP product by AuNP color change was compared with detection by visual turbidity. The optimal conditions for this new LAMP-AuNP assay were an incubation time of 20min and a temperature of 65°C. After LAMP amplification was complete, its products were hybridized with the AuNP probe for 5min and then detected by the addition of magnesium salt. The color changed from red to blue as a result of aggregation of the AuNP probe under high ionic strength conditions produced by the addition of the salt. The sensitivity of the LAMP-AuNP assay was greater than the LAMP turbidity assay by up to 10-fold for both HPV genotypes. The LAMP-AuNP assay showed higher sensitivity and ease of visualization than did the LAMP turbidity for the detection of HPV16 and HPV18. Additionally, AuNP-HPV16 and AuNP-HPV18 probes were stable for over 1year. The combination of LAMP and the AuNP-probe colorimetric assay offers a simple, rapid and highly sensitive alternative diagnostic tool for the detection of HPV16 and HPV18 in district hospitals or field studies. Copyright © 2016 Elsevier B.V. All rights reserved.

How low can you go? Changing the resolution of novel complex objects in visual working memory according to task demands

PubMed Central

Allon, Ayala S.; Balaban, Halely; Luria, Roy

2014-01-01

In three experiments we manipulated the resolution of novel complex objects in visual working memory (WM) by changing task demands. Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli. We used the contralateral delay activity as an electrophysiological marker to directly track the deployment of visual WM resources while participants preformed a change-detection task. Across three experiments we presented the same novel complex items but changed the task demands. In Experiment 1 we induced a medium resolution task by using change trials in which a random polygon changed to a different type of polygon and replicated previous findings showing that novel complex objects are represented with higher resolution relative to simple familiar objects. In Experiment 2 we induced a low resolution task that required distinguishing between polygons and other types of stimulus categories, but we failed in finding a corresponding decrease in the resolution of the represented item. Finally, in Experiment 3 we induced a high resolution task that required discriminating between highly similar polygons with somewhat different contours. This time, we observed an increase in the item’s resolution. Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM. These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms. PMID:24734026

Color-Changing Sensors for Detecting the Presence of Hypergolic Fuels

NASA Technical Reports Server (NTRS)

Roberson, Luke; Captain, Janine; Santiago-Maldonado, Edgardo; Starr, Stanley; DeVor, Robert

2013-01-01

Hypergolic fuel sensors were designed to incorporate novel chemochromic pigments into substrates for use in various methods of leak detection. There are several embodiments to this invention that would provide specific visual indication of hypergols used during and after transfer. The ability to incorporate these pigments into various polymer matrices provides a unique opportunity to manufacture nearly any type of sensor shape that is required. The vibrant color change from yellow to black instantaneously shows the worker the presence of hypergols in the area.

Relative saliency in change signals affects perceptual comparison and decision processes in change detection.

PubMed

Yang, Cheng-Ta

2011-12-01

Change detection requires perceptual comparison and decision processes on different features of multiattribute objects. How relative salience between two feature-changes influences the processes has not been addressed. This study used the systems factorial technology to investigate the processes when detecting changes in a Gabor patch with visual inputs from orientation and spatial frequency channels. Two feature-changes were equally salient in Experiment 1, but a frequency-change was more salient than an orientation-change in Experiment 2. Results showed that all four observers adopted parallel self-terminating processing with limited- to unlimited-capacity processing in Experiment 1. In Experiment 2, one observer used parallel self-terminating processing with unlimited-capacity processing, and the others adopted serial self-terminating processing with limited- to unlimited-capacity processing to detect changes. Postexperimental interview revealed that subjective utility of feature information underlay the adoption of a decision strategy. These results highlight that observers alter decision strategies in change detection depending on the relative saliency in change signals, with relative saliency being determined by both physical salience and subjective weight of feature information. When relative salience exists, individual differences in the process characteristics emerge.

Witnessing the first sign of retinitis pigmentosa onset in the allegedly normal eye of a case of unilateral RP: a 30-year follow-up.

PubMed

Gauvin, Mathieu; Chakor, Hadi; Koenekoop, Robert K; Little, John M; Lina, Jean-Marc; Lachapelle, Pierre

2016-06-01

A patient initially presented with constricted visual field, attenuated retinal vasculature, pigmentary clumping and reduced ERG in OS only, suggestive of unilateral retinitis pigmentosa (RP). This patient was subsequently seen on eight occasions (over three decades), and, with time, the initially normal eye (OD) gradually showed signs of RP-like degeneration. The purpose of this study was to evaluate which clinical modality (visual field, funduscopy or electroretinography) could have first predicted this fate. At each time points, data obtained from our patient were compared to normative data using Z tests. At initial visit, all tests were significantly (p < 0.05) altered in OS and normal in OD. Visual field and retinal vessel diameter in OD reduced gradually to reach statistical significance at the 5th visit and 6th visit (21 and 22 years after the first examination, respectively). In OD, the amplitude of the scotopic and photopic ERGs reduced gradually and was significantly smaller than normal at the 2nd visit (after 11 years) and 3rd visit (after 18 years), respectively. When the photopic ERG was analyzed using the discrete wavelet transform (DWT), we were able to detect a significant change at the 2nd visit (after 11 years) instead of the 3rd visit (18 years). Our study allowed us to witness the earliest manifestation of an RP disease process. The ERG was the first test to detect significant RP changes. A significantly earlier detection of ERG anomalies was obtained when the DWT was used, demonstrating its advantage for early detection of ERG changes.

Do experts and novices direct attention differently in examining physics diagrams? A study of change detection using the flicker technique

NASA Astrophysics Data System (ADS)

Morphew, Jason W.; Mestre, Jose P.; Ross, Brian H.; Strand, Natalie E.

2015-12-01

It is known that experts identify or perceive meaningful patterns in visual stimuli related to their domain of expertise. This study explores the speed with which experts and novices detect changes in physics diagrams. Since change detection depends on where individuals direct their attention, differences in the speed with which experts and novices detect changes to diagrams would suggest differences in attention allocation between experts and novices. We present data from an experiment using the "flicker technique," in which both physics experts and physics novices viewed nearly identical pairs of diagrams that are representative of typical introductory physics situations. The two diagrams in each pair contain a subtle difference that either does or does not change the underlying physics depicted in the diagram. Findings indicate that experts are faster at detecting physics-relevant changes than physics-irrelevant changes; however, there is no difference in response time for novices, suggesting that expertise guides attention for experts when inspecting physics diagrams. We discuss the cognitive implications of our findings.

Improved In vivo Assessment of Pulmonary Fibrosis in Mice using X-Ray Dark-Field Radiography

NASA Astrophysics Data System (ADS)

Yaroshenko, Andre; Hellbach, Katharina; Yildirim, Ali Önder; Conlon, Thomas M.; Fernandez, Isis Enlil; Bech, Martin; Velroyen, Astrid; Meinel, Felix G.; Auweter, Sigrid; Reiser, Maximilian; Eickelberg, Oliver; Pfeiffer, Franz

2015-12-01

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease with a median life expectancy of 4-5 years after initial diagnosis. Early diagnosis and accurate monitoring of IPF are limited by a lack of sensitive imaging techniques that are able to visualize early fibrotic changes at the epithelial-mesenchymal interface. Here, we report a new x-ray imaging approach that directly visualizes the air-tissue interfaces in mice in vivo. This imaging method is based on the detection of small-angle x-ray scattering that occurs at the air-tissue interfaces in the lung. Small-angle scattering is detected with a Talbot-Lau interferometer, which provides the so-called x-ray dark-field signal. Using this imaging modality, we demonstrate-for the first time-the quantification of early pathogenic changes and their correlation with histological changes, as assessed by stereological morphometry. The presented radiography method is significantly more sensitive in detecting morphological changes compared with conventional x-ray imaging, and exhibits a significantly lower radiation dose than conventional x-ray CT. As a result of the improved imaging sensitivity, this new imaging modality could be used in future to reduce the number of animals required for pulmonary research studies.

BioMon: A Google Earth Based Continuous Biomass Monitoring System (Demo Paper)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vatsavai, Raju

2009-01-01

We demonstrate a Google Earth based novel visualization system for continuous monitoring of biomass at regional and global scales. This system is integrated with a back-end spatiotemporal data mining system that continuously detects changes using high temporal resolution MODIS images. In addition to the visualization, we demonstrate novel query features of the system that provides insights into the current conditions of the landscape.

Visual working memory capacity for color is independent of representation resolution.

PubMed

Ye, Chaoxiong; Zhang, Lingcong; Liu, Taosheng; Li, Hong; Liu, Qiang

2014-01-01

The relationship between visual working memory (VWM) capacity and resolution of representation have been extensively investigated. Several recent ERP studies using orientation (or arrow) stimuli suggest that there is an inverse relationship between VWM capacity and representation resolution. However, different results have been obtained in studies using color stimuli. This could be due to important differences in the experimental paradigms used in previous studies. We examined whether the same relationship between capacity and resolution holds for color information. Participants performed a color change detection task while their electroencephalography was recorded. We manipulated representation resolution by asking participants to detect either a salient change (low-resolution) or a subtle change (high-resolution) in color. We used an ERP component known as contralateral delay activity (CDA) to index the amount of information maintained in VWM. The result demonstrated the same pattern for both low- and high-resolution conditions, with no difference between conditions. This result suggests that VWM always represents a fixed number of approximately 3-4 colors regardless of the resolution of representation.

Familiarity enhances visual working memory for faces.

PubMed

Jackson, Margaret C; Raymond, Jane E

2008-06-01

Although it is intuitive that familiarity with complex visual objects should aid their preservation in visual working memory (WM), empirical evidence for this is lacking. This study used a conventional change-detection procedure to assess visual WM for unfamiliar and famous faces in healthy adults. Across experiments, faces were upright or inverted and a low- or high-load concurrent verbal WM task was administered to suppress contribution from verbal WM. Even with a high verbal memory load, visual WM performance was significantly better and capacity estimated as significantly greater for famous versus unfamiliar faces. Face inversion abolished this effect. Thus, neither strategic, explicit support from verbal WM nor low-level feature processing easily accounts for the observed benefit of high familiarity for visual WM. These results demonstrate that storage of items in visual WM can be enhanced if robust visual representations of them already exist in long-term memory.

Highly selective and rapidly responsive fluorescent probe for hydrogen sulfide detection in wine.

PubMed

Wang, Hao; Wang, Jialin; Yang, Shaoxiang; Tian, Hongyu; Liu, Yongguo; Sun, Baoguo

2018-08-15

A new fluorescent probe 6-(2, 4-dinitrophenoxy)-2-naphthonitrile (probe 1) was designed and synthesized for the selective detection of hydrogen sulfide (H 2 S). The addition of H 2 S to a solution of probe 1 resulted in a marked fluorescence turn-on alongside a visual color change from colorless to light yellow. Importantly, this distinct color response indicated that probe 1 could be used as a visual sensor for H 2 S. Moreover, probe 1 was successfully used as a signal tool to determine the H 2 S levels in beer and red wine. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Reaction-Based Novel Fluorescent Probe for Detection of Hydrogen Sulfide and Its Application in Wine.

PubMed

Wang, Hao; Wang, Jialin; Yang, Shaoxiang; Tian, Hongyu; Sun, Baoguo; Liu, Yongguo

2018-01-01

A new reaction-based fluorescent probe 6-cyanonaphthalen-2-yl-2,4- dinitrobenzenesulfonate (probe 1) was designed and synthesized for detection of hydrogen sulfide (H 2 S). The addition of H 2 S to a solution of probe 1 resulted in a marked fluorescence increased accompanied by a visual color change from colorless to yellow. Importantly, this distinct color response indicates that probe 1 could be used as a visual tool for detection of H 2 S. H 2 S can be detected quantitatively in the concentration range 0 to 25 μM and the detection limit was 30 nM. Moreover, probe 1 was successfully used as a sensor to determine H 2 S levels in red wine and beer. Fluorescent probe 1 could be employed as a visible sensor for H 2 S. Probe 1 could be used to detect H 2 S quantitatively in food simple. © 2017 Institute of Food Technologists®.

Detection Progress of Selected Drugs in TLC

PubMed Central

Pyka, Alina

2014-01-01

This entry describes applications of known indicators and dyes as new visualizing reagents and various visualizing systems as well as photocatalytic reactions and bioautography method for the detection of bioactive compounds including drugs and compounds isolated from herbal extracts. Broadening index, detection index, characteristics of densitometric band, modified contrast index, limit of detection, densitometric visualizing index, and linearity range of detected compounds were used for the evaluation of visualizing effects of applied visualizing reagents. It was shown that visualizing effect depends on the chemical structure of the visualizing reagent, the structure of the substance detected, and the chromatographic adsorbent applied. The usefulness of densitometry to direct detection of some drugs was also shown. Quoted papers indicate the detection progress of selected drugs investigated by thin-layer chromatography (TLC). PMID:24551853

Foliar fungi of Betula pendula: impact of tree species mixtures and assessment methods

PubMed Central

Nguyen, Diem; Boberg, Johanna; Cleary, Michelle; Bruelheide, Helge; Hönig, Lydia; Koricheva, Julia; Stenlid, Jan

2017-01-01

Foliar fungi of silver birch (Betula pendula) in an experimental Finnish forest were investigated across a gradient of tree species richness using molecular high-throughput sequencing and visual macroscopic assessment. We hypothesized that the molecular approach detects more fungal taxa than visual assessment, and that there is a relationship among the most common fungal taxa detected by both techniques. Furthermore, we hypothesized that the fungal community composition, diversity, and distribution patterns are affected by changes in tree diversity. Sequencing revealed greater diversity of fungi on birch leaves than the visual assessment method. One species showed a linear relationship between the methods. Species-specific variation in fungal community composition could be partially explained by tree diversity, though overall fungal diversity was not affected by tree diversity. Analysis of specific fungal taxa indicated tree diversity effects at the local neighbourhood scale, where the proportion of birch among neighbouring trees varied, but not at the plot scale. In conclusion, both methods may be used to determine tree diversity effects on the foliar fungal community. However, high-throughput sequencing provided higher resolution of the fungal community, while the visual macroscopic assessment detected functionally active fungal species. PMID:28150710

A Temporal Same-Object Advantage in the Tunnel Effect: Facilitated Change Detection for Persisting Objects

ERIC Educational Resources Information Center

Flombaum, Jonathan I.; Scholl, Brian J.

2006-01-01

Meaningful visual experience requires computations that identify objects as the same persisting individuals over time, motion, occlusion, and featural change. This article explores these computations in the tunnel effect: When an object moves behind an occluder, and then an object later emerges following a consistent trajectory, observers…

Subtle changes in the landmark panorama disrupt visual navigation in a nocturnal bull ant

PubMed Central

2017-01-01

The ability of ants to navigate when the visual landmark information is altered has often been tested by creating large and artificial discrepancies in their visual environment. Here, we had an opportunity to slightly modify the natural visual environment around the nest of the nocturnal bull ant Myrmecia pyriformis. We achieved this by felling three dead trees, two located along the typical route followed by the foragers of that particular nest and one in a direction perpendicular to their foraging direction. An image difference analysis showed that the change in the overall panorama following the removal of these trees was relatively little. We filmed the behaviour of ants close to the nest and tracked their entire paths, both before and after the trees were removed. We found that immediately after the trees were removed, ants walked slower and were less directed. Their foraging success decreased and they looked around more, including turning back to look towards the nest. We document how their behaviour changed over subsequent nights and discuss how the ants may detect and respond to a modified visual environment in the evening twilight period. This article is part of the themed issue ‘Vision in dim light’. PMID:28193813

Exogenous attention influences visual short-term memory in infants.

PubMed

Ross-Sheehy, Shannon; Oakes, Lisa M; Luck, Steven J

2011-05-01

Two experiments examined the hypothesis that developing visual attentional mechanisms influence infants' Visual Short-Term Memory (VSTM) in the context of multiple items. Five- and 10-month-old infants (N = 76) received a change detection task in which arrays of three differently colored squares appeared and disappeared. On each trial one square changed color and one square was cued; sometimes the cued item was the changing item, and sometimes the changing item was not the cued item. Ten-month-old infants exhibited enhanced memory for the cued item when the cue was a spatial pre-cue (Experiment 1) and 5-month-old infants exhibited enhanced memory for the cued item when the cue was relative motion (Experiment 2). These results demonstrate for the first time that infants younger than 6 months can encode information in VSTM about individual items in multiple-object arrays, and that attention-directing cues influence both perceptual and VSTM encoding of stimuli in infants as in adults.

Neural mechanism for sensing fast motion in dim light.

PubMed

Li, Ran; Wang, Yi

2013-11-07

Luminance is a fundamental property of visual scenes. A population of neurons in primary visual cortex (V1) is sensitive to uniform luminance. In natural vision, however, the retinal image often changes rapidly. Consequently the luminance signals visual cells receive are transiently varying. How V1 neurons respond to such luminance changes is unknown. By applying large static uniform stimuli or grating stimuli altering at 25 Hz that resemble the rapid luminance changes in the environment, we show that approximately 40% V1 cells responded to rapid luminance changes of uniform stimuli. Most of them strongly preferred luminance decrements. Importantly, when tested with drifting gratings, the preferred speeds of these cells were significantly higher than cells responsive to static grating stimuli but not to uniform stimuli. This responsiveness can be accounted for by the preferences for low spatial frequencies and high temporal frequencies. These luminance-sensitive cells subserve the detection of fast motion under the conditions of dim illumination.

Eye movements and attention: The role of pre-saccadic shifts of attention in perception, memory and the control of saccades

PubMed Central

Gersch, Timothy M.; Schnitzer, Brian S.; Dosher, Barbara A.; Kowler, Eileen

2012-01-01

Saccadic eye movements and perceptual attention work in a coordinated fashion to allow selection of the objects, features or regions with the greatest momentary need for limited visual processing resources. This study investigates perceptual characteristics of pre-saccadic shifts of attention during a sequence of saccades using the visual manipulations employed to study mechanisms of attention during maintained fixation. The first part of this paper reviews studies of the connections between saccades and attention, and their significance for both saccadic control and perception. The second part presents three experiments that examine the effects of pre-saccadic shifts of attention on vision during sequences of saccades. Perceptual enhancements at the saccadic goal location relative to non-goal locations were found across a range of stimulus contrasts, with either perceptual discrimination or detection tasks, with either single or multiple perceptual targets, and regardless of the presence of external noise. The results show that the preparation of saccades can evoke a variety of attentional effects, including attentionally-mediated changes in the strength of perceptual representations, selection of targets for encoding in visual memory, exclusion of external noise, or changes in the levels of internal visual noise. The visual changes evoked by saccadic planning make it possible for the visual system to effectively use saccadic eye movements to explore the visual environment. PMID:22809798

Attending to unrelated targets boosts short-term memory for color arrays.

PubMed

Makovski, Tal; Swallow, Khena M; Jiang, Yuhong V

2011-05-01

Detecting a target typically impairs performance in a second, unrelated task. It has been recently reported however, that detecting a target in a stream of distractors can enhance long-term memory of faces and scenes that were presented concurrently with the target (the attentional boost effect). In this study we ask whether target detection also enhances performance in a visual short-term memory task, where capacity limits are severe. Participants performed two tasks at once: a one shot, color change detection task and a letter-detection task. In Experiment 1, a central letter appeared at the same time as 3 or 5 color patches (memory display). Participants encoded the colors and pressed the spacebar if the letter was a T (target). After a short retention interval, a probe display of color patches appeared. Performance on the change detection task was enhanced when a target, rather than a distractor, appeared with the memory display. This effect was not modulated by memory load or the frequency of trials in which a target appeared. However, there was no enhancement when the target appeared at the same time as the probe display (Experiment 2a) or during the memory retention interval (Experiment 2b). Together these results suggest that detecting a target facilitates the encoding of unrelated information into visual short-term memory. Copyright © 2010 Elsevier Ltd. All rights reserved.

Comparison of hoop-net trapping and visual surveys to monitor abundance of the Rio Grande cooter (Pseudemys gorzugi).

PubMed

Mali, Ivana; Duarte, Adam; Forstner, Michael R J

2018-01-01

Abundance estimates play an important part in the regulatory and conservation decision-making process. It is important to correct monitoring data for imperfect detection when using these data to track spatial and temporal variation in abundance, especially in the case of rare and elusive species. This paper presents the first attempt to estimate abundance of the Rio Grande cooter ( Pseudemys gorzugi ) while explicitly considering the detection process. Specifically, in 2016 we monitored this rare species at two sites along the Black River, New Mexico via traditional baited hoop-net traps and less invasive visual surveys to evaluate the efficacy of these two sampling designs. We fitted the Huggins closed-capture estimator to estimate capture probabilities using the trap data and distance sampling models to estimate detection probabilities using the visual survey data. We found that only the visual survey with the highest number of observed turtles resulted in similar abundance estimates to those estimated using the trap data. However, the estimates of abundance from the remaining visual survey data were highly variable and often underestimated abundance relative to the estimates from the trap data. We suspect this pattern is related to changes in the basking behavior of the species and, thus, the availability of turtles to be detected even though all visual surveys were conducted when environmental conditions were similar. Regardless, we found that riverine habitat conditions limited our ability to properly conduct visual surveys at one site. Collectively, this suggests visual surveys may not be an effective sample design for this species in this river system. When analyzing the trap data, we found capture probabilities to be highly variable across sites and between age classes and that recapture probabilities were much lower than initial capture probabilities, highlighting the importance of accounting for detectability when monitoring this species. Although baited hoop-net traps seem to be an effective sampling design, it is important to note that this method required a relatively high trap effort to reliably estimate abundance. This information will be useful when developing a larger-scale, long-term monitoring program for this species of concern.

Establishing upper limits on neuronal activity-evoked pH changes with APT-CEST MRI at 7 T.

PubMed

Khlebnikov, Vitaliy; Siero, Jeroen C W; Bhogal, Alex A; Luijten, Peter R; Klomp, Dennis W J; Hoogduin, Hans

2018-07-01

To detect neuronal activity-evoked pH changes by amide proton transfer-chemical exchange saturation transfer (APT-CEST) MRI at 7 T. Three healthy subjects participated in the study. A low-power 3-dimensional APT-CEST sequence was optimized through the Bloch-McConnell equations. pH sensitivity of the sequence was estimated both in phantoms and in vivo. The feasibility of pH-functional MRI was tested in Bloch-McConnell-simulated data using the optimized sequence. In healthy subjects, the visual stimuli were used to evoke transient pH changes in the visual cortex, and a 3-dimensional APT-CEST volume was acquired at the pH-sensitive frequency offset of 3.5 ppm every 12.6 s. In theory, a three-component general linear model was capable of separating the effects of blood oxygenation level-dependent contrast and pH. The Bloch-McConnell equations indicated that a change in pH of 0.03 should be measurable at the experimentally determined temporal signal-to-noise ratio of 108. However, only a blood oxygenation level-dependent effect in the visual cortex could be discerned during the visual stimuli experiments performed in the healthy subjects. The results of this study suggest that if indeed there are any transient brain pH changes in response to visual stimuli, those are under 0.03 units pH change, which is extremely difficult to detect using the existent techniques. Magn Reson Med 80:126-136, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

[The role of sustained attention in shift-contingent change blindness].

PubMed

Nakashima, Ryoichi; Yokosawa, Kazuhiko

2015-02-01

Previous studies of change blindness have examined the effect of temporal factors (e.g., blank duration) on attention in change detection. This study examined the effect of spatial factors (i.e., whether the locations of original and changed objects are the same or different) on attention in change detection, using a shift-contingent change blindness task. We used a flicker paradigm in which the location of a to-be-judged target image was manipulated (shift, no-shift). In shift conditions, the image of an array of objects was spatially shifted so that all objects appeared in new locations; in no-shift conditions, all object images of an array appeared at the same location. The presence of visual stimuli (dots) in the blank display between the two images was.manipulated (dot, no-dot) under the assumption that abrupt onsets of these stimuli would capture attention. Results indicated that change detection performance was improved by exogenous attentional capture in the shift condition. Thus, we suggest that attention can play an important role in change detection during shift-contingent change blindness.

Multi-chamber nucleic acid amplification and detection device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dugan, Lawrence

A nucleic acid amplification and detection device includes an amplification cartridge with a plurality of reaction chambers for containing an amplification reagent and a visual detection reagent, and a plurality of optically transparent view ports for viewing inside the reaction chambers. The cartridge also includes a sample receiving port which is adapted to receive a fluid sample and fluidically connected to distribute the fluid sample to the reaction chamber, and in one embodiment, a plunger is carried by the cartridge for occluding fluidic communication to the reaction chambers. The device also includes a heating apparatus having a heating element whichmore » is activated by controller to generate heat when a trigger event is detected. The heating apparatus includes a cartridge-mounting section which positioned a cartridge in thermal communication with the heating element so that visual changes to the contents of the reaction chambers are viewable through the view ports.« less

A novel reaction-based fluorescent probe for the detection of cysteine in milk and water samples.

PubMed

Wang, Jialin; Wang, Hao; Hao, Yanfeng; Yang, Shaoxiang; Tian, Hongyu; Sun, Baoguo; Liu, Yongguo

2018-10-01

A novel fluorescent probe 3'-hydroxy-3-oxo-3H-spiro [isobenzofuran-1,9'-xanthene]-6'-yl-2,4-dinitrobenzenesulfonate (probe 1) was designed and synthesized as a visual sensor for the detection of cysteine levels in milk and water samples. The addition of cysteine to the solution of probe 1 resulted in an increase in fluorescence intensity and color change, from light yellow to yellow-green. The distinct color response indicated that probe 1 could be used as a visual sensor for cysteine. Cysteine can be detected quantitatively at concentrations between 0 and 400 μM and the detection limit of the fluorescence response to the probe was 6.5 μM. This suggests that probe 1 could be used as a signaling tool to determine the cysteine levels in samples, such as milk and water. Copyright © 2018 Elsevier Ltd. All rights reserved.

The footprints of visual attention in the Posner cueing paradigm revealed by classification images

NASA Technical Reports Server (NTRS)

Eckstein, Miguel P.; Shimozaki, Steven S.; Abbey, Craig K.

2002-01-01

In the Posner cueing paradigm, observers' performance in detecting a target is typically better in trials in which the target is present at the cued location than in trials in which the target appears at the uncued location. This effect can be explained in terms of a Bayesian observer where visual attention simply weights the information differently at the cued (attended) and uncued (unattended) locations without a change in the quality of processing at each location. Alternatively, it could also be explained in terms of visual attention changing the shape of the perceptual filter at the cued location. In this study, we use the classification image technique to compare the human perceptual filters at the cued and uncued locations in a contrast discrimination task. We did not find statistically significant differences between the shapes of the inferred perceptual filters across the two locations, nor did the observed differences account for the measured cueing effects in human observers. Instead, we found a difference in the magnitude of the classification images, supporting the idea that visual attention changes the weighting of information at the cued and uncued location, but does not change the quality of processing at each individual location.

Strand Displacement Amplification Reaction on Quantum Dot-Encoded Silica Bead for Visual Detection of Multiplex MicroRNAs.

PubMed

Qu, Xiaojun; Jin, Haojun; Liu, Yuqian; Sun, Qingjiang

2018-03-06

The combination of microbead array, isothermal amplification, and molecular signaling enables the continuous development of next-generation molecular diagnostic techniques. Herein we reported the implementation of nicking endonuclease-assisted strand displacement amplification reaction on quantum dots-encoded microbead (Qbead), and demonstrated its feasibility for multiplexed miRNA assay in real sample. The Qbead featured with well-defined core-shell superstructure with dual-colored quantum dots loaded in silica core and shell, respectively, exhibiting remarkably high optical encoding stability. Specially designed stem-loop-structured probes were immobilized onto the Qbead for specific target recognition and amplification. In the presence of low abundance of miRNA target, the target triggered exponential amplification, producing a large quantity of stem-G-quadruplexes, which could be selectively signaled by a fluorescent G-quadruplex intercalator. In one-step operation, the Qbead-based isothermal amplification and signaling generated emissive "core-shell-satellite" superstructure, changing the Qbead emission-color. The target abundance-dependent emission-color changes of the Qbead allowed direct, visual detection of specific miRNA target. This visualization method achieved limit of detection at the subfemtomolar level with a linear dynamic range of 4.5 logs, and point-mutation discrimination capability for precise miRNA analyses. The array of three encoded Qbeads could simultaneously quantify three miRNA biomarkers in ∼500 human hepatoma carcinoma cells. With the advancements in ease of operation, multiplexing, and visualization capabilities, the isothermal amplification-on-Qbead assay could potentially enable the development of point-of-care diagnostics.

Robotic Attention Processing And Its Application To Visual Guidance

NASA Astrophysics Data System (ADS)

Barth, Matthew; Inoue, Hirochika

1988-03-01

This paper describes a method of real-time visual attention processing for robots performing visual guidance. This robot attention processing is based on a novel vision processor, the multi-window vision system that was developed at the University of Tokyo. The multi-window vision system is unique in that it only processes visual information inside local area windows. These local area windows are quite flexible in their ability to move anywhere on the visual screen, change their size and shape, and alter their pixel sampling rate. By using these windows for specific attention tasks, it is possible to perform high speed attention processing. The primary attention skills of detecting motion, tracking an object, and interpreting an image are all performed at high speed on the multi-window vision system. A basic robotic attention scheme using the attention skills was developed. The attention skills involved detection and tracking of salient visual features. The tracking and motion information thus obtained was utilized in producing the response to the visual stimulus. The response of the attention scheme was quick enough to be applicable to the real-time vision processing tasks of playing a video 'pong' game, and later using an automobile driving simulator. By detecting the motion of a 'ball' on a video screen and then tracking the movement, the attention scheme was able to control a 'paddle' in order to keep the ball in play. The response was faster than that of a human's, allowing the attention scheme to play the video game at higher speeds. Further, in the application to the driving simulator, the attention scheme was able to control both direction and velocity of a simulated vehicle following a lead car. These two applications show the potential of local visual processing in its use for robotic attention processing.

Visual short-term memory capacity for simple and complex objects.

PubMed

Luria, Roy; Sessa, Paola; Gotler, Alex; Jolicoeur, Pierre; Dell'Acqua, Roberto

2010-03-01

Does the capacity of visual short-term memory (VSTM) depend on the complexity of the objects represented in memory? Although some previous findings indicated lower capacity for more complex stimuli, other results suggest that complexity effects arise during retrieval (due to errors in the comparison process with what is in memory) that is not related to storage limitations of VSTM, per se. We used ERPs to track neuronal activity specifically related to retention in VSTM by measuring the sustained posterior contralateral negativity during a change detection task (which required detecting if an item was changed between a memory and a test array). The sustained posterior contralateral negativity, during the retention interval, was larger for complex objects than for simple objects, suggesting that neurons mediating VSTM needed to work harder to maintain more complex objects. This, in turn, is consistent with the view that VSTM capacity depends on complexity.

Efficacy of Intravitreal Anti-vascular Endothelial Growth Factor or Steroid Injection in Diabetic Macular Edema According to Fluid Turbidity in Optical Coherence Tomography

PubMed Central

Lee, Kyungmin; Chung, Heeyoung; Park, Youngsuk

2014-01-01

Purpose To determine if short term effects of intravitreal anti-vascular endothelial growth factor or steroid injection are correlated with fluid turbidity, as detected by spectral domain optical coherence tomography (SD-OCT) in diabetic macular edema (DME) patients. Methods A total of 583 medical records were reviewed and 104 cases were enrolled. Sixty eyes received a single intravitreal bevacizumab injection (IVB) on the first attack of DME and 44 eyes received triamcinolone acetonide treatment (IVTA). Intraretinal fluid turbidity in DME patients was estimated with initialintravitreal SD-OCT and analyzed with color histograms from a Photoshop program. Central macular thickness and visual acuity using a logarithm from the minimum angle of resolution chart, were assessed at the initial period and 2 months after injections. Results Visual acuity and central macular thickness improved after injections in both groups. In the IVB group, visual acuity and central macular thickness changed less as the intraretinal fluid became more turbid. In the IVTA group, visual acuity underwent less change while central macular thickness had a greater reduction (r = -0.675, p = 0.001) as the intraretinal fluid was more turbid. Conclusions IVB and IVTA injections were effective in reducing central macular thickness and improving visual acuity in DME patients. Further, fluid turbidity, which was detected by SD-OCT may be one of the indexes that highlight the influence of the steroid-dependent pathogenetic mechanism. PMID:25120338

Efficacy of intravitreal anti-vascular endothelial growth factor or steroid injection in diabetic macular edema according to fluid turbidity in optical coherence tomography.

PubMed

Lee, Kyungmin; Chung, Heeyoung; Park, Youngsuk; Sohn, Joonhong

2014-08-01

To determine if short term effects of intravitreal anti-vascular endothelial growth factor or steroid injection are correlated with fluid turbidity, as detected by spectral domain optical coherence tomography (SD-OCT) in diabetic macular edema (DME) patients. A total of 583 medical records were reviewed and 104 cases were enrolled. Sixty eyes received a single intravitreal bevacizumab injection (IVB) on the first attack of DME and 44 eyes received triamcinolone acetonide treatment (IVTA). Intraretinal fluid turbidity in DME patients was estimated with initial intravitreal SD-OCT and analyzed with color histograms from a Photoshop program. Central macular thickness and visual acuity using a logarithm from the minimum angle of resolution chart, were assessed at the initial period and 2 months after injections. Visual acuity and central macular thickness improved after injections in both groups. In the IVB group, visual acuity and central macular thickness changed less as the intraretinal fluid became more turbid. In the IVTA group, visual acuity underwent less change while central macular thickness had a greater reduction (r = -0.675, p = 0.001) as the intraretinal fluid was more turbid. IVB and IVTA injections were effective in reducing central macular thickness and improving visual acuity in DME patients. Further, fluid turbidity, which was detected by SD-OCT may be one of the indexes that highlight the influence of the steroid-dependent pathogenetic mechanism.

Deception Detection in Multicultural Coalitions: Foundations for a Cognitive Model

DTIC Science & Technology

2011-06-01

and spontaneous vs. deliberate and contrived facial expression of emotions , symmetry, leakage through microexpressions, hand postures, dynamic...sequences of visually detectable cues , such as facial muscle-group coordination and correlations expressed as changes in facial expressions and face...concert, whereas facial expressions of deceivers emphasize a few cues that arise more randomly and chaotically [15]. A smile without the use of

Contextual remapping in visual search after predictable target-location changes.

PubMed

Conci, Markus; Sun, Luning; Müller, Hermann J

2011-07-01

Invariant spatial context can facilitate visual search. For instance, detection of a target is faster if it is presented within a repeatedly encountered, as compared to a novel, layout of nontargets, demonstrating a role of contextual learning for attentional guidance ('contextual cueing'). Here, we investigated how context-based learning adapts to target location (and identity) changes. Three experiments were performed in which, in an initial learning phase, observers learned to associate a given context with a given target location. A subsequent test phase then introduced identity and/or location changes to the target. The results showed that contextual cueing could not compensate for target changes that were not 'predictable' (i.e. learnable). However, for predictable changes, contextual cueing remained effective even immediately after the change. These findings demonstrate that contextual cueing is adaptive to predictable target location changes. Under these conditions, learned contextual associations can be effectively 'remapped' to accommodate new task requirements.

Can Probability Maps of Swept-Source Optical Coherence Tomography Predict Visual Field Changes in Preperimetric Glaucoma?

PubMed

Lee, Won June; Kim, Young Kook; Jeoung, Jin Wook; Park, Ki Ho

2017-12-01

To determine the usefulness of swept-source optical coherence tomography (SS-OCT) probability maps in detecting locations with significant reduction in visual field (VF) sensitivity or predicting future VF changes, in patients with classically defined preperimetric glaucoma (PPG). Of 43 PPG patients, 43 eyes were followed-up on every 6 months for at least 2 years were analyzed in this longitudinal study. The patients underwent wide-field SS-OCT scanning and standard automated perimetry (SAP) at the time of enrollment. With this wide-scan protocol, probability maps originating from the corresponding thickness map and overlapped with SAP VF test points could be generated. We evaluated the vulnerable VF points with SS-OCT probability maps as well as the prevalence of locations with significant VF reduction or subsequent VF changes observed in the corresponding damaged areas of the probability maps. The vulnerable VF points were shown in superior and inferior arcuate patterns near the central fixation. In 19 of 43 PPG eyes (44.2%), significant reduction in baseline VF was detected within the areas of structural change on the SS-OCT probability maps. In 16 of 43 PPG eyes (37.2%), subsequent VF changes within the areas of SS-OCT probability map change were observed over the course of the follow-up. Structural changes on SS-OCT probability maps could detect or predict VF changes using SAP, in a considerable number of PPG eyes. Careful comparison of probability maps with SAP results could be useful in diagnosing and monitoring PPG patients in the clinical setting.

Faces do not capture special attention in children with autism spectrum disorder: a change blindness study.

PubMed

Kikuchi, Yukiko; Senju, Atsushi; Tojo, Yoshikuni; Osanai, Hiroo; Hasegawa, Toshikazu

2009-01-01

Two experiments investigated attention of children with autism spectrum disorder (ASD) to faces and objects. In both experiments, children (7- to 15-year-olds) detected the difference between 2 visual scenes. Results in Experiment 1 revealed that typically developing children (n = 16) detected the change in faces faster than in objects, whereas children with ASD (n = 16) were equally fast in detecting changes in faces and objects. These results were replicated in Experiment 2 (n = 16 in children with ASD and 22 in typically developing children), which does not require face recognition skill. Results suggest that children with ASD lack an attentional bias toward others' faces, which could contribute to their atypical social orienting.

Colorimetric detection of Cucumber green mottle mosaic virus using unmodified gold nanoparticles as colorimetric probes.

PubMed

Wang, Lin; Liu, Zhanmin; Xia, Xueying; Yang, Cuiyun; Huang, Junyi; Wan, Sibao

2017-05-01

Cucumber green mottle mosaic virus (CGMMV)causes a severe mosaic symptom of watermelon and cucumber, and can be transmitted via infected cucumber seeds, leaves and soil. It remains a challenge to detect this virus to prevent its introduction and infection and spread in fields. For this purpose, a simple and sensitive label-free colorimetric detection method for CGMMV has been developed with unmodified gold nanoparticles (AuNPs) as colorimetric probes. The method is based on the finding that the presence of RT-PCR target products of CGMMV and species-specific probes results in color change of AuNPs from red to blue after NaCl induction. Normally, species-specific probes attach to the surface of AuNPs and thereby increasing their resistance to NaCl-induced aggregation. The concentration of sodium, probes in the reaction system and evaluation of specificity and sensitivity of a novel assay, visual detection of Cucumber green mottle mosaic virus using unmodified AuNPs has been carried out with simple preparation of samples in our study. Through this assay, as low as 30pg/μL of CGMMV RNA was thus detected visually, by the naked eye, without the need for any sophisticated, expensive instrumentation and biochemical reagents. The specificity was 100% and exhibited good reproducibility in our assays. The results note that this assay is highly species-specific, simple, low-cost, and visual for easy detection of CGMMV in plant tissues. Therefore, visual assay is a potentially useful tool for middle or small-scales corporations and entry-exit inspection and quarantine bureau to detect CGMMV in cucumber seeds or plant tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

Polymer Vesicle Sensor for Visual and Sensitive Detection of SO2 in Water.

PubMed

Huang, Tong; Hou, Zhilin; Xu, Qingsong; Huang, Lei; Li, Chuanlong; Zhou, Yongfeng

2017-01-10

This study reports the first polymer vesicle sensor for the visual detection of SO 2 and its derivatives in water. A strong binding ability between tertiary alkanolamines and SO 2 has been used as the driving force for the detection by the graft of tertiary amine alcohol (TAA) groups onto an amphiphilic hyperbranched multiarm polymer, which can self-assemble into vesicles with enriched TAA groups on the surface. The polymer vesicles will undergo proton exchange with cresol red (CR) to produce CR-immobilized vesicles (CR@vesicles). Subsequently, through competitive binding with the TAA groups between CR and SO 2 or HSO 3 - , the CR@vesicles (purple) can quickly change into SO 2 @vesicles (colorless) with the release of protonated CR (yellow). Such a fast purple to yellow transition in the solution allows the visual detection of SO 2 or its derivatives in water by the naked eye. A visual test paper for SO 2 gas has also been demonstrated by the adsorption of CR@vesicles onto paper. Meanwhile, the detection limit of CR@vesicles for HSO 3 - is approximately 25 nM, which is improved by approximately 30 times when compared with that of small molecule-based sensors with a similar structure (0.83 μM). Such an enhanced detection sensitivity should be related to the enrichment of TAA groups as well as the CR in CR@vesicles. In addition, the CR@vesicle sensors also show selectivity and specificity for the detection of SO 2 or HSO 3 - among anions such as F - , Br - , Cl - , SO 4 2- , NO 2 - , C 2 O 4 2- , S 2 O 3 2- , SCN - , AcO - , SO 3 2- , S 2- , and HCO 3 - .

The Effect of Local Orientation Change on the Detection of Contours Defined by Constant Curvature: Psychophysics and Image Statistics.

PubMed

Khuu, Sieu K; Cham, Joey; Hayes, Anthony

2016-01-01

In the present study, we investigated the detection of contours defined by constant curvature and the statistics of curved contours in natural scenes. In Experiment 1, we examined the degree to which human sensitivity to contours is affected by changing the curvature angle and disrupting contour curvature continuity by varying the orientation of end elements. We find that (1) changing the angle of contour curvature decreased detection performance, while (2) end elements oriented in the direction (i.e., clockwise) of curvature facilitated contour detection regardless of the curvature angle of the contour. In Experiment 2 we further established that the relative effect of end-element orientation on contour detection was not only dependent on their orientation (collinear or cocircular), but also their spatial separation from the contour, and whether the contour shape was curved or not (i.e., C-shaped or S-shaped). Increasing the spatial separation of end-elements reduced contour detection performance regardless of their orientation or the contour shape. However, at small separations, cocircular end-elements facilitated the detection of C-shaped contours, but not S-shaped contours. The opposite result was observed for collinear end-elements, which improved the detection of S- shaped, but not C-shaped contours. These dissociative results confirmed that the visual system specifically codes contour curvature, but the association of contour elements occurs locally. Finally, we undertook an analysis of natural images that mapped contours with a constant angular change and determined the frequency of occurrence of end elements with different orientations. Analogous to our behavioral data, this image analysis revealed that the mapped end elements of constantly curved contours are likely to be oriented clockwise to the angle of curvature. Our findings indicate that the visual system is selectively sensitive to contours defined by constant curvature and that this might reflect the properties of curved contours in natural images.

Detecting target changes in multiple object tracking with peripheral vision: More pronounced eccentricity effects for changes in form than in motion.

PubMed

Vater, Christian; Kredel, Ralf; Hossner, Ernst-Joachim

2017-05-01

In the current study, dual-task performance is examined with multiple-object tracking as a primary task and target-change detection as a secondary task. The to-be-detected target changes in conditions of either change type (form vs. motion; Experiment 1) or change salience (stop vs. slowdown; Experiment 2), with changes occurring at either near (5°-10°) or far (15°-20°) eccentricities (Experiments 1 and 2). The aim of the study was to test whether changes can be detected solely with peripheral vision. By controlling for saccades and computing gaze distances, we could show that participants used peripheral vision to monitor the targets and, additionally, to perceive changes at both near and far eccentricities. Noticeably, gaze behavior was not affected by the actual target change. Detection rates as well as response times generally varied as a function of change condition and eccentricity, with faster detections for motion changes and near changes. However, in contrast to the effects found for motion changes, sharp declines in detection rates and increased response times were observed for form changes as a function of the eccentricities. This result can be ascribed to properties of the visual system, namely to the limited spatial acuity in the periphery and the comparably receptive motion sensitivity of peripheral vision. These findings show that peripheral vision is functional for simultaneous target monitoring and target-change detection as saccadic information suppression can be avoided and covert attention can be optimally distributed to all targets. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Smart photonic coating as a new visualization technique of strain deformation of metal plates

NASA Astrophysics Data System (ADS)

Fudouzi, Hiroshi; Sawada, Tsutomu; Tanaka, Yoshikazu; Ario, Ichiro; Hyakutake, Tsuyoshi; Nishizaki, Itaru

2012-04-01

We will present a simple and low cost method to visualize local strain distribution in deformed aluminum plates. In this study, aluminum plates were coated with opal photonic crystal film with tunable structural color. The photonic crystal films consist of a silicone elastomer that contains an array of submicron polystyrene colloidal particles. When the aluminum sheets were stretched, the change in the spacing of the colloidal particles in the opal film alters the color of the film. This approach could be useful as a new strain gauge having a visual indicator to detect mechanical deformation.

Changing scenes: memory for naturalistic events following change blindness.

PubMed

Mäntylä, Timo; Sundström, Anna

2004-11-01

Research on scene perception indicates that viewers often fail to detect large changes to scene regions when these changes occur during a visual disruption such as a saccade or a movie cut. In two experiments, we examined whether this relative inability to detect changes would produce systematic biases in event memory. In Experiment 1, participants decided whether two successively presented images were the same or different, followed by a memory task, in which they recalled the content of the viewed scene. In Experiment 2, participants viewed a short video, in which an actor carried out a series of daily activities, and central scenes' attributes were changed during a movie cut. A high degree of change blindness was observed in both experiments, and these effects were related to scene complexity (Experiment 1) and level of retrieval support (Experiment 2). Most important, participants reported the changed, rather than the initial, event attributes following a failure in change detection. These findings suggest that attentional limitations during encoding contribute to biases in episodic memory.

Feature-Based Change Detection Reveals Inconsistent Individual Differences in Visual Working Memory Capacity.

PubMed

Ambrose, Joseph P; Wijeakumar, Sobanawartiny; Buss, Aaron T; Spencer, John P

2016-01-01

Visual working memory (VWM) is a key cognitive system that enables people to hold visual information in mind after a stimulus has been removed and compare past and present to detect changes that have occurred. VWM is severely capacity limited to around 3-4 items, although there are robust individual differences in this limit. Importantly, these individual differences are evident in neural measures of VWM capacity. Here, we capitalized on recent work showing that capacity is lower for more complex stimulus dimension. In particular, we asked whether individual differences in capacity remain consistent if capacity is shifted by a more demanding task, and, further, whether the correspondence between behavioral and neural measures holds across a shift in VWM capacity. Participants completed a change detection (CD) task with simple colors and complex shapes in an fMRI experiment. As expected, capacity was significantly lower for the shape dimension. Moreover, there were robust individual differences in behavioral estimates of VWM capacity across dimensions. Similarly, participants with a stronger BOLD response for color also showed a strong neural response for shape within the lateral occipital cortex, intraparietal sulcus (IPS), and superior IPS. Although there were robust individual differences in the behavioral and neural measures, we found little evidence of systematic brain-behavior correlations across feature dimensions. This suggests that behavioral and neural measures of capacity provide different views onto the processes that underlie VWM and CD. Recent theoretical approaches that attempt to bridge between behavioral and neural measures are well positioned to address these findings in future work.

Automated UAV-based mapping for airborne reconnaissance and video exploitation

NASA Astrophysics Data System (ADS)

Se, Stephen; Firoozfam, Pezhman; Goldstein, Norman; Wu, Linda; Dutkiewicz, Melanie; Pace, Paul; Naud, J. L. Pierre

2009-05-01

Airborne surveillance and reconnaissance are essential for successful military missions. Such capabilities are critical for force protection, situational awareness, mission planning, damage assessment and others. UAVs gather huge amount of video data but it is extremely labour-intensive for operators to analyse hours and hours of received data. At MDA, we have developed a suite of tools towards automated video exploitation including calibration, visualization, change detection and 3D reconstruction. The on-going work is to improve the robustness of these tools and automate the process as much as possible. Our calibration tool extracts and matches tie-points in the video frames incrementally to recover the camera calibration and poses, which are then refined by bundle adjustment. Our visualization tool stabilizes the video, expands its field-of-view and creates a geo-referenced mosaic from the video frames. It is important to identify anomalies in a scene, which may include detecting any improvised explosive devices (IED). However, it is tedious and difficult to compare video clips to look for differences manually. Our change detection tool allows the user to load two video clips taken from two passes at different times and flags any changes between them. 3D models are useful for situational awareness, as it is easier to understand the scene by visualizing it in 3D. Our 3D reconstruction tool creates calibrated photo-realistic 3D models from video clips taken from different viewpoints, using both semi-automated and automated approaches. The resulting 3D models also allow distance measurements and line-of- sight analysis.

Detection of Post-Therapeutic Effects in Breast Carcinoma Using Hard X-Ray Index of Refraction Computed Tomography - A Feasibility Study.

PubMed

Grandl, Susanne; Sztrókay-Gaul, Anikó; Mittone, Alberto; Gasilov, Sergey; Brun, Emmanuel; Bravin, Alberto; Mayr, Doris; Auweter, Sigrid D; Hellerhoff, Karin; Reiser, Maximilian; Coan, Paola

2016-01-01

Neoadjuvant chemotherapy is the state-of-the-art treatment in advanced breast cancer. A correct visualization of the post-therapeutic tumor size is of high prognostic relevance. X-ray phase-contrast computed tomography (PC-CT) has been shown to provide improved soft-tissue contrast at a resolution formerly restricted to histopathology, at low doses. This study aimed at assessing ex-vivo the potential use of PC-CT for visualizing the effects of neoadjuvant chemotherapy on breast carcinoma. The analysis was performed on two ex-vivo formalin-fixed mastectomy samples containing an invasive carcinoma removed from two patients treated with neoadjuvant chemotherapy. Images were matched with corresponding histological slices. The visibility of typical post-therapeutic tissue changes was assessed and compared to results obtained with conventional clinical imaging modalities. PC-CT depicted the different tissue types with an excellent correlation to histopathology. Post-therapeutic tissue changes were correctly visualized and the residual tumor mass could be detected. PC-CT outperformed clinical imaging modalities in the detection of chemotherapy-induced tissue alterations including post-therapeutic tumor size. PC-CT might become a unique diagnostic tool in the prediction of tumor response to neoadjuvant chemotherapy. PC-CT might be used to assist during histopathological diagnosis, offering a high-resolution and high-contrast virtual histological tool for the accurate delineation of tumor boundaries.

Control system of hexacopter using color histogram footprint and convolutional neural network

NASA Astrophysics Data System (ADS)

Ruliputra, R. N.; Darma, S.

2017-07-01

The development of unmanned aerial vehicles (UAV) has been growing rapidly in recent years. The use of logic thinking which is implemented into the program algorithms is needed to make a smart system. By using visual input from a camera, UAV is able to fly autonomously by detecting a target. However, some weaknesses arose as usage in the outdoor environment might change the target's color intensity. Color histogram footprint overcomes the problem because it divides color intensity into separate bins that make the detection tolerant to the slight change of color intensity. Template matching compare its detection result with a template of the reference image to determine the target position and use it to position the vehicle in the middle of the target with visual feedback control based on Proportional-Integral-Derivative (PID) controller. Color histogram footprint method localizes the target by calculating the back projection of its histogram. It has an average success rate of 77 % from a distance of 1 meter. It can position itself in the middle of the target by using visual feedback control with an average positioning time of 73 seconds. After the hexacopter is in the middle of the target, Convolutional Neural Networks (CNN) classifies a number contained in the target image to determine a task depending on the classified number, either landing, yawing, or return to launch. The recognition result shows an optimum success rate of 99.2 %.

[The relationship between eyeball structure and visual acuity in high myopia].

PubMed

Liu, Yi-Chang; Xia, Wen-Tao; Zhu, Guang-You; Zhou, Xing-Tao; Fan, Li-Hua; Liu, Rui-Jue; Chen, Jie-Min

2010-06-01

To explore the relationship between eyeball structure and visual acuity in high myopia. Totally, 152 people (283 eyeballs) with different levels of myopia were tested for visual acuity, axial length, and fundus. All cases were classified according to diopter, axial length, and fundus. The relationships between diopter, axial length, fundus and visual acuity were studied. The mathematical models were established for visual acuity and eyeball structure markers. The visual acuity showed a moderate correlation with fundus class, comus, axial length and diopter ([r] > 0.4, P < 0.000 1). The visual acuity in people with the axial length longer than 30.00 mm, diopter above -20.00 D and fundus in 4th class were mostly below 0.5. The mathematical models were established by visual acuity and eyeball structure markers. The visual acuity should decline with axial length extension, diopter deepening and pathological deterioration of fundus. To detect the structure changes by combining different kinds of objective methods can help to assess and to judge the vision in high myopia.

Learning to Link Visual Contours

PubMed Central

Li, Wu; Piëch, Valentin; Gilbert, Charles D.

2008-01-01

SUMMARY In complex visual scenes, linking related contour elements is important for object recognition. This process, thought to be stimulus driven and hard wired, has substrates in primary visual cortex (V1). Here, however, we find contour integration in V1 to depend strongly on perceptual learning and top-down influences that are specific to contour detection. In naive monkeys the information about contours embedded in complex backgrounds is absent in V1 neuronal responses, and is independent of the locus of spatial attention. Training animals to find embedded contours induces strong contour-related responses specific to the trained retinotopic region. These responses are most robust when animals perform the contour detection task, but disappear under anesthesia. Our findings suggest that top-down influences dynamically adapt neural circuits according to specific perceptual tasks. This may serve as a general neuronal mechanism of perceptual learning, and reflect top-down mediated changes in cortical states. PMID:18255036

Qualitative similarities in the visual short-term memory of pigeons and people.

PubMed

Gibson, Brett; Wasserman, Edward; Luck, Steven J

2011-10-01

Visual short-term memory plays a key role in guiding behavior, and individual differences in visual short-term memory capacity are strongly predictive of higher cognitive abilities. To provide a broader evolutionary context for understanding this memory system, we directly compared the behavior of pigeons and humans on a change detection task. Although pigeons had a lower storage capacity and a higher lapse rate than humans, both species stored multiple items in short-term memory and conformed to the same basic performance model. Thus, despite their very different evolutionary histories and neural architectures, pigeons and humans have functionally similar visual short-term memory systems, suggesting that the functional properties of visual short-term memory are subject to similar selective pressures across these distant species.

Spectral Reflectance of Duckweed (Lemna Gibba L.) Fronds Exposed to Ethylene Glycol

NASA Technical Reports Server (NTRS)

Dong, Weijin; Carter, Gregory A.; Barber, John T.

2001-01-01

When duckweed (Lemna Gibba L.) fronds are exposed to ethylene glycol (EG) anatomy is altered, allowing an increase in water uptake that causes a darkening of frond appearance. Spectroradiometry was used to quantify changes in frond reflectance that occurred throughout the 400-850 nm spectrum under various EG concentrations and exposure times. The threshold concentration of EG at which a reflectance change could be detected was between 35 and 40 mM, approximately the same as by visual observation. EG-induced changes in frond reflectance were maximum at concentrations of 50 mM or greater. Reflectance changes were detectable within 24h of exposure to 100 mM EG,2-3 days prior to changes in frond appearance. The spectroradiometry of duckweed may serve as a rapid and sensitive technique for detection of ecosystem exposure to EG and perhaps other stress agents.

Prefrontal Neuronal Responses during Audiovisual Mnemonic Processing

PubMed Central

Hwang, Jaewon

2015-01-01

During communication we combine auditory and visual information. Neurophysiological research in nonhuman primates has shown that single neurons in ventrolateral prefrontal cortex (VLPFC) exhibit multisensory responses to faces and vocalizations presented simultaneously. However, whether VLPFC is also involved in maintaining those communication stimuli in working memory or combining stored information across different modalities is unknown, although its human homolog, the inferior frontal gyrus, is known to be important in integrating verbal information from auditory and visual working memory. To address this question, we recorded from VLPFC while rhesus macaques (Macaca mulatta) performed an audiovisual working memory task. Unlike traditional match-to-sample/nonmatch-to-sample paradigms, which use unimodal memoranda, our nonmatch-to-sample task used dynamic movies consisting of both facial gestures and the accompanying vocalizations. For the nonmatch conditions, a change in the auditory component (vocalization), the visual component (face), or both components was detected. Our results show that VLPFC neurons are activated by stimulus and task factors: while some neurons simply responded to a particular face or a vocalization regardless of the task period, others exhibited activity patterns typically related to working memory such as sustained delay activity and match enhancement/suppression. In addition, we found neurons that detected the component change during the nonmatch period. Interestingly, some of these neurons were sensitive to the change of both components and therefore combined information from auditory and visual working memory. These results suggest that VLPFC is not only involved in the perceptual processing of faces and vocalizations but also in their mnemonic processing. PMID:25609614

Changes of Visual Pathway and Brain Connectivity in Glaucoma: A Systematic Review

PubMed Central

Nuzzi, Raffaele; Dallorto, Laura; Rolle, Teresa

2018-01-01

Background: Glaucoma is a leading cause of irreversible blindness worldwide. The increasing interest in the involvement of the cortical visual pathway in glaucomatous patients is due to the implications in recent therapies, such as neuroprotection and neuroregeneration. Objective: In this review, we outline the current understanding of brain structural, functional, and metabolic changes detected with the modern techniques of neuroimaging in glaucomatous subjects. Methods: We screened MEDLINE, EMBASE, CINAHL, CENTRAL, LILACS, Trip Database, and NICE for original contributions published until 31 October 2017. Studies with at least six patients affected by any type of glaucoma were considered. We included studies using the following neuroimaging techniques: functional Magnetic Resonance Imaging (fMRI), resting-state fMRI (rs-fMRI), magnetic resonance spectroscopy (MRS), voxel- based Morphometry (VBM), surface-based Morphometry (SBM), diffusion tensor MRI (DTI). Results: Over a total of 1,901 studies, 56 case series with a total of 2,381 patients were included. Evidence of neurodegenerative process in glaucomatous patients was found both within and beyond the visual system. Structural alterations in visual cortex (mainly reduced cortex thickness and volume) have been demonstrated with SBM and VBM; these changes were not limited to primary visual cortex but also involved association visual areas. Other brain regions, associated with visual function, demonstrated a certain grade of increased or decreased gray matter volume. Functional and metabolic abnormalities resulted within primary visual cortex in all studies with fMRI and MRS. Studies with rs-fMRI found disrupted connectivity between the primary and higher visual cortex and between visual cortex and associative visual areas in the task-free state of glaucomatous patients. Conclusions: This review contributes to the better understanding of brain abnormalities in glaucoma. It may stimulate further speculation about brain plasticity at a later age and therapeutic strategies, such as the prevention of cortical degeneration in patients with glaucoma. Structural, functional, and metabolic neuroimaging methods provided evidence of changes throughout the visual pathway in glaucomatous patients. Other brain areas, not directly involved in the processing of visual information, also showed alterations. PMID:29896087

Sensitivity of the lane change test as a measure of in-vehicle system demand.

PubMed

Young, Kristie L; Lenné, Michael G; Williamson, Amy R

2011-05-01

The Lane Change Test (LCT) is one of the growing number of methods developed to quantify driving performance degradation brought about by the use of in-vehicle devices. Beyond its validity and reliability, for such a test to be of practical use, it must also be sensitive to the varied demands of individual tasks. The current study evaluated the ability of several recent LCT lateral control and event detection parameters to discriminate between visual-manual and cognitive surrogate In-Vehicle Information System tasks with different levels of demand. Twenty-seven participants (mean age 24.4 years) completed a PC version of the LCT while performing visual search and math problem solving tasks. A number of the lateral control metrics were found to be sensitive to task differences, but the event detection metrics were less able to discriminate between tasks. The mean deviation and lane excursion measures were able to distinguish between the visual and cognitive tasks, but were less sensitive to the different levels of task demand. The other LCT metrics examined were less sensitive to task differences. A major factor influencing the sensitivity of at least some of the LCT metrics could be the type of lane change instructions given to participants. The provision of clear and explicit lane change instructions and further refinement of its metrics will be essential for increasing the utility of the LCT as an evaluation tool. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Common and Innovative Visuals: A sparsity modeling framework for video.

PubMed

Abdolhosseini Moghadam, Abdolreza; Kumar, Mrityunjay; Radha, Hayder

2014-05-02

Efficient video representation models are critical for many video analysis and processing tasks. In this paper, we present a framework based on the concept of finding the sparsest solution to model video frames. To model the spatio-temporal information, frames from one scene are decomposed into two components: (i) a common frame, which describes the visual information common to all the frames in the scene/segment, and (ii) a set of innovative frames, which depicts the dynamic behaviour of the scene. The proposed approach exploits and builds on recent results in the field of compressed sensing to jointly estimate the common frame and the innovative frames for each video segment. We refer to the proposed modeling framework by CIV (Common and Innovative Visuals). We show how the proposed model can be utilized to find scene change boundaries and extend CIV to videos from multiple scenes. Furthermore, the proposed model is robust to noise and can be used for various video processing applications without relying on motion estimation and detection or image segmentation. Results for object tracking, video editing (object removal, inpainting) and scene change detection are presented to demonstrate the efficiency and the performance of the proposed model.

Ghosting reduction method for color anaglyphs

NASA Astrophysics Data System (ADS)

Chang, An Jin; Kim, Hye Jin; Choi, Jae Wan; Yu, Ki Yun

2008-02-01

Anaglyph is the simplest and the most economical method for 3D visualization. However, anaglyph has several drawbacks such as loss of color or visual discomfort, e.g., region merging and the ghosting effect. In particular, the ghosting effect, which is caused by green penetrating to the left eye, brings on a slight headache, dizziness and vertigo. Therefore, ghosting effects have to be reduced to improve the visual quality and make viewing of the anaglyph comfortable. Since red lightness is increased by penetration by green, the lightness of the red band has to be compensated for. In this paper, a simple deghosting method is proposed using the red lightness difference of the left and right images. We detected a ghosting area with the criterion, which was calculated from the statistics of the difference image, and then the red lightness of the anaglyph was changed to be brighter or darker according to the degree of the difference. The amount of change of red lightness was determined empirically. These adjustments simultaneously reduced the ghosting effect and preserved the color lightness within the non-ghosting area. The proposed deghosting method works well, and the goal of this paper was to detect the ghosting area automatically and to reduce the ghosting.

Assessment of an Onboard EO Sensor to Enable Detect-and-Sense Capability for UAVs Operating in a Cluttered Environment

DTIC Science & Technology

2017-09-01

via visual sensors onboard the UAV. Both the hardware and software architecture design are discussed at length. Then, a series of tests that were...visual sensors onboard the UAV. Both the hardware and software architecture design are discussed at length. Then, a series of tests that were conducted...and representing the change in time . (1) Horn and Schunck (1981) further simplified this equation by taking the Taylor series

Touch influences perceived gloss

PubMed Central

Adams, Wendy J.; Kerrigan, Iona S.; Graf, Erich W.

2016-01-01

Identifying an object’s material properties supports recognition and action planning: we grasp objects according to how heavy, hard or slippery we expect them to be. Visual cues to material qualities such as gloss have recently received attention, but how they interact with haptic (touch) information has been largely overlooked. Here, we show that touch modulates gloss perception: objects that feel slippery are perceived as glossier (more shiny).Participants explored virtual objects that varied in look and feel. A discrimination paradigm (Experiment 1) revealed that observers integrate visual gloss with haptic information. Observers could easily detect an increase in glossiness when it was paired with a decrease in friction. In contrast, increased glossiness coupled with decreased slipperiness produced a small perceptual change: the visual and haptic changes counteracted each other. Subjective ratings (Experiment 2) reflected a similar interaction – slippery objects were rated as glossier and vice versa. The sensory system treats visual gloss and haptic friction as correlated cues to surface material. Although friction is not a perfect predictor of gloss, the visual system appears to know and use a probabilistic relationship between these variables to bias perception – a sensible strategy given the ambiguity of visual clues to gloss. PMID:26915492

Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

PubMed Central

Authié, Colas N.; Berthoz, Alain; Sahel, José-Alain; Safran, Avinoam B.

2017-01-01

In retinitis pigmentosa (RP), loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present), of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures. PMID:28798674

Age-related changes in visual exploratory behavior in a natural scene setting

PubMed Central

Hamel, Johanna; De Beukelaer, Sophie; Kraft, Antje; Ohl, Sven; Audebert, Heinrich J.; Brandt, Stephan A.

2013-01-01

Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view). To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age, and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game-experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media. PMID:23801970

Metacognitive Confidence Increases with, but Does Not Determine, Visual Perceptual Learning.

PubMed

Zizlsperger, Leopold; Kümmel, Florian; Haarmeier, Thomas

2016-01-01

While perceptual learning increases objective sensitivity, the effects on the constant interaction of the process of perception and its metacognitive evaluation have been rarely investigated. Visual perception has been described as a process of probabilistic inference featuring metacognitive evaluations of choice certainty. For visual motion perception in healthy, naive human subjects here we show that perceptual sensitivity and confidence in it increased with training. The metacognitive sensitivity-estimated from certainty ratings by a bias-free signal detection theoretic approach-in contrast, did not. Concomitant 3Hz transcranial alternating current stimulation (tACS) was applied in compliance with previous findings on effective high-low cross-frequency coupling subserving signal detection. While perceptual accuracy and confidence in it improved with training, there were no statistically significant tACS effects. Neither metacognitive sensitivity in distinguishing between their own correct and incorrect stimulus classifications, nor decision confidence itself determined the subjects' visual perceptual learning. Improvements of objective performance and the metacognitive confidence in it were rather determined by the perceptual sensitivity at the outset of the experiment. Post-decision certainty in visual perceptual learning was neither independent of objective performance, nor requisite for changes in sensitivity, but rather covaried with objective performance. The exact functional role of metacognitive confidence in human visual perception has yet to be determined.

Detection of Functional Change Using Cluster Trend Analysis in Glaucoma.

PubMed

Gardiner, Stuart K; Mansberger, Steven L; Demirel, Shaban

2017-05-01

Global analyses using mean deviation (MD) assess visual field progression, but can miss localized changes. Pointwise analyses are more sensitive to localized progression, but more variable so require confirmation. This study assessed whether cluster trend analysis, averaging information across subsets of locations, could improve progression detection. A total of 133 test-retest eyes were tested 7 to 10 times. Rates of change and P values were calculated for possible re-orderings of these series to generate global analysis ("MD worsening faster than x dB/y with P < y"), pointwise and cluster analyses ("n locations [or clusters] worsening faster than x dB/y with P < y") with specificity exactly 95%. These criteria were applied to 505 eyes tested over a mean of 10.5 years, to find how soon each detected "deterioration," and compared using survival models. This was repeated including two subsequent visual fields to determine whether "deterioration" was confirmed. The best global criterion detected deterioration in 25% of eyes in 5.0 years (95% confidence interval [CI], 4.7-5.3 years), compared with 4.8 years (95% CI, 4.2-5.1) for the best cluster analysis criterion, and 4.1 years (95% CI, 4.0-4.5) for the best pointwise criterion. However, for pointwise analysis, only 38% of these changes were confirmed, compared with 61% for clusters and 76% for MD. The time until 25% of eyes showed subsequently confirmed deterioration was 6.3 years (95% CI, 6.0-7.2) for global, 6.3 years (95% CI, 6.0-7.0) for pointwise, and 6.0 years (95% CI, 5.3-6.6) for cluster analyses. Although the specificity is still suboptimal, cluster trend analysis detects subsequently confirmed deterioration sooner than either global or pointwise analyses.

The multiple disguises of spiders: web colour and decorations, body colour and movement

PubMed Central

Théry, Marc; Casas, Jérôme

2008-01-01

Diverse functions have been assigned to the visual appearance of webs, spiders and web decorations, including prey attraction, predator deterrence and camouflage. Here, we review the pertinent literature, focusing on potential camouflage and mimicry. Webs are often difficult to detect in a heterogeneous visual environment. Static and dynamic web distortions are used to escape visual detection by prey, although particular silk may also attract prey. Recent work using physiological models of vision taking into account visual environments rarely supports the hypothesis of spider camouflage by decorations, but most often the prey attraction and predator confusion hypotheses. Similarly, visual modelling shows that spider coloration is effective in attracting prey but not in conveying camouflage. Camouflage through colour change might be used by particular crab spiders to hide from predator or prey on flowers of different coloration. However, results obtained on a non-cryptic crab spider suggest that an alternative function of pigmentation may be to avoid UV photodamage through the transparent cuticle. Numerous species are clearly efficient locomotory mimics of ants, particularly in the eyes of their predators. We close our paper by highlighting gaps in our knowledge. PMID:18990672

Neural basis of forward flight control and landing in honeybees.

PubMed

Ibbotson, M R; Hung, Y-S; Meffin, H; Boeddeker, N; Srinivasan, M V

2017-11-06

The impressive repertoire of honeybee visually guided behaviors, and their ability to learn has made them an important tool for elucidating the visual basis of behavior. Like other insects, bees perform optomotor course correction to optic flow, a response that is dependent on the spatial structure of the visual environment. However, bees can also distinguish the speed of image motion during forward flight and landing, as well as estimate flight distances (odometry), irrespective of the visual scene. The neural pathways underlying these abilities are unknown. Here we report on a cluster of descending neurons (DNIIIs) that are shown to have the directional tuning properties necessary for detecting image motion during forward flight and landing on vertical surfaces. They have stable firing rates during prolonged periods of stimulation and respond to a wide range of image speeds, making them suitable to detect image flow during flight behaviors. While their responses are not strictly speed tuned, the shape and amplitudes of their speed tuning functions are resistant to large changes in spatial frequency. These cells are prime candidates not only for the control of flight speed and landing, but also the basis of a neural 'front end' of the honeybee's visual odometer.

Altering attentional control settings causes persistent biases of visual attention.

PubMed

Knight, Helen C; Smith, Daniel T; Knight, David C; Ellison, Amanda

2016-01-01

Attentional control settings have an important role in guiding visual behaviour. Previous work within cognitive psychology has found that the deployment of general attentional control settings can be modulated by training. However, research has not yet established whether long-term modifications of one particular type of attentional control setting can be induced. To address this, we investigated persistent alterations to feature search mode, also known as an attentional bias, towards an arbitrary stimulus in healthy participants. Subjects were biased towards the colour green by an information sheet. Attentional bias was assessed using a change detection task. After an interval of either 1 or 2 weeks, participants were then retested on the same change detection task, tested on a different change detection task where colour was irrelevant, or were biased towards an alternative colour. One experiment included trials in which the distractor stimuli (but never the target stimuli) were green. The key finding was that green stimuli in the second task attracted attention, despite this impairing task performance. Furthermore, inducing a second attentional bias did not override the initial bias toward green objects. The attentional bias also persisted for at least two weeks. It is argued that this persistent attentional bias is mediated by a chronic change to participants' attentional control settings, which is aided by long-term representations involving contextual cueing. We speculate that similar changes to attentional control settings and continuous cueing may relate to attentional biases observed in psychopathologies. Targeting these biases may be a productive approach to treatment.

Visual perception of fatigued lifting actions.

PubMed

Fischer, Steven L; Albert, Wayne J; McGarry, Tim

2012-12-01

Fatigue-related changes in lifting kinematics may expose workers to undue injury risks. Early detection of accumulating fatigue offers the prospect of intervention strategies to mitigate such fatigue-related risks. In a first step towards this objective, this study investigated whether fatigue detection was accessible to visual perception and, if so, what was the key visual information required for successful fatigue discrimination. Eighteen participants were tasked with identifying fatigued lifts when viewing 24 trials presented using both video and point-light representations. Each trial comprised a pair of lifting actions containing a fresh and a fatigued lift from the same individual presented in counter-balanced sequence. Confidence intervals demonstrated that the frequency of correct responses for both sexes exceeded chance expectations (50%) for both video (68%±12%) and point-light representations (67%±10%), demonstrating that fatigued lifting kinematics are open to visual perception. There were no significant differences between sexes or viewing condition, the latter result indicating kinematic dynamics as providing sufficient information for successful fatigue discrimination. Moreover, results from single viewer investigation reported fatigue detection (75%) from point-light information describing only the kinematics of the box lifted. These preliminary findings may have important workplace applications if fatigue discrimination rates can be improved upon through future research. Copyright © 2012 Elsevier B.V. All rights reserved.

Developmental plasticity in vision and behavior may help guppies overcome increased turbidity.

PubMed

Ehlman, Sean M; Sandkam, Benjamin A; Breden, Felix; Sih, Andrew

2015-12-01

Increasing turbidity in streams and rivers near human activity is cause for environmental concern, as the ability of aquatic organisms to use visual information declines. To investigate how some organisms might be able to developmentally compensate for increasing turbidity, we reared guppies (Poecilia reticulata) in either clear or turbid water. We assessed the effects of developmental treatments on adult behavior and aspects of the visual system by testing fish from both developmental treatments in turbid and clear water. We found a strong interactive effect of rearing and assay conditions: fish reared in clear water tended to decrease activity in turbid water, whereas fish reared in turbid water tended to increase activity in turbid water. Guppies from all treatments decreased activity when exposed to a predator. To measure plasticity in the visual system, we quantified treatment differences in opsin gene expression of individuals. We detected a shift from mid-wave-sensitive opsins to long wave-sensitive opsins for guppies reared in turbid water. Since long-wavelength sensitivity is important in motion detection, this shift likely allows guppies to salvage motion-detecting abilities when visual information is obscured in turbid water. Our results demonstrate the importance of developmental plasticity in responses of organisms to rapidly changing environments.

Beyond the real world: attention debates in auditory mismatch negativity.

PubMed

Chung, Kyungmi; Park, Jin Young

2018-04-11

The aim of this study was to address the potential for the auditory mismatch negativity (aMMN) to be used in applied event-related potential (ERP) studies by determining whether the aMMN would be an attention-dependent ERP component and could be differently modulated across visual tasks or virtual reality (VR) stimuli with different visual properties and visual complexity levels. A total of 80 participants, aged 19-36 years, were assigned to either a reading-task (21 men and 19 women) or a VR-task (22 men and 18 women) group. Two visual-task groups of healthy young adults were matched in age, sex, and handedness. All participants were instructed to focus only on the given visual tasks and ignore auditory change detection. While participants in the reading-task group read text slides, those in the VR-task group viewed three 360° VR videos in a random order and rated how visually complex the given virtual environment was immediately after each VR video ended. Inconsistent with the finding of a partial significant difference in perceived visual complexity in terms of brightness of virtual environments, both visual properties of distance and brightness showed no significant differences in the modulation of aMMN amplitudes. A further analysis was carried out to compare elicited aMMN amplitudes of a typical MMN task and an applied VR task. No significant difference in the aMMN amplitudes was found across the two groups who completed visual tasks with different visual-task demands. In conclusion, the aMMN is a reliable ERP marker of preattentive cognitive processing for auditory deviance detection.

Historical photometric evidence for volatile migration on Triton

NASA Technical Reports Server (NTRS)

Buratti, Bonnie J.; Goguen, Jay D.; Gibson, James; Mosher, Joel

1994-01-01

Analysis of CCD images of Triton obtained with the 1.5-m telescope on Palomar Mountain shows that in the time period surrounding the Voyager 2 encounter with the satellite (1985-1990), no changes in the satellite's visual albedo or color occurred. The published observations of Triton in the 0.35- to 0.60-micrometer spectral region obtained between 1950 and 1990 were reanalyzed to detect historical variability in both its albedo and visual color. Analysis of the photometry indicates that there is little, if any, change in Triton's visual geometric albedo. This result is consistent with the albedo pattern observed by Voyager and the change in sub-Earth latitude. Two distinct types of color changes are evident: a significant secular increase in the blue region of the visual spectrum since at least the 1950s, and the reported dramatic reddening of Triton's spectrum in the late 1970s. The latter change can be explained only by a short-lived geological phenomenon. Triton's changing pole orientation with respect to a terrestrial observer cannot explain the secular color changes. These changes imply volatile transport on a global scale on Triton's surface during the past 4 decades. We present two models which show that either removal of a red volatile from Triton's polar cap or deposition of a blue volatile in the equatorial regions can explain the secular color changes. A third possibility is that the changes are the result of the alpha-beta phase transition of nitrogen and subsequent fracturing of the polar cap region (N. S. Duxbury and R. H. Brown (1993).

Human visual system-based smoking event detection

NASA Astrophysics Data System (ADS)

Odetallah, Amjad D.; Agaian, Sos S.

2012-06-01

Human action (e.g. smoking, eating, and phoning) analysis is an important task in various application domains like video surveillance, video retrieval, human-computer interaction systems, and so on. Smoke detection is a crucial task in many video surveillance applications and could have a great impact to raise the level of safety of urban areas, public parks, airplanes, hospitals, schools and others. The detection task is challenging since there is no prior knowledge about the object's shape, texture and color. In addition, its visual features will change under different lighting and weather conditions. This paper presents a new scheme of a system for detecting human smoking events, or small smoke, in a sequence of images. In developed system, motion detection and background subtraction are combined with motion-region-saving, skin-based image segmentation, and smoke-based image segmentation to capture potential smoke regions which are further analyzed to decide on the occurrence of smoking events. Experimental results show the effectiveness of the proposed approach. As well, the developed method is capable of detecting the small smoking events of uncertain actions with various cigarette sizes, colors, and shapes.

Obstacle Detection in Indoor Environment for Visually Impaired Using Mobile Camera

NASA Astrophysics Data System (ADS)

Rahman, Samiur; Ullah, Sana; Ullah, Sehat

2018-01-01

Obstacle detection can improve the mobility as well as the safety of visually impaired people. In this paper, we present a system using mobile camera for visually impaired people. The proposed algorithm works in indoor environment and it uses a very simple technique of using few pre-stored floor images. In indoor environment all unique floor types are considered and a single image is stored for each unique floor type. These floor images are considered as reference images. The algorithm acquires an input image frame and then a region of interest is selected and is scanned for obstacle using pre-stored floor images. The algorithm compares the present frame and the next frame and compute mean square error of the two frames. If mean square error is less than a threshold value α then it means that there is no obstacle in the next frame. If mean square error is greater than α then there are two possibilities; either there is an obstacle or the floor type is changed. In order to check if the floor is changed, the algorithm computes mean square error of next frame and all stored floor types. If minimum of mean square error is less than a threshold value α then flour is changed otherwise there exist an obstacle. The proposed algorithm works in real-time and 96% accuracy has been achieved.

To See or Not to See: Investigating Detectability of Ganges River Dolphins Using a Combined Visual-Acoustic Survey

PubMed Central

Richman, Nadia I.; Gibbons, James M.; Turvey, Samuel T.; Akamatsu, Tomonari; Ahmed, Benazir; Mahabub, Emile; Smith, Brian D.; Jones, Julia P. G.

2014-01-01

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring. PMID:24805782

To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.

PubMed

Richman, Nadia I; Gibbons, James M; Turvey, Samuel T; Akamatsu, Tomonari; Ahmed, Benazir; Mahabub, Emile; Smith, Brian D; Jones, Julia P G

2014-01-01

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring.

Age-Related Changes in the Ability to Switch between Temporal and Spatial Attention.

PubMed

Callaghan, Eleanor; Holland, Carol; Kessler, Klaus

2017-01-01

Background : Identifying age-related changes in cognition that contribute towards reduced driving performance is important for the development of interventions to improve older adults' driving and prolong the time that they can continue to drive. While driving, one is often required to switch from attending to events changing in time, to distribute attention spatially. Although there is extensive research into both spatial attention and temporal attention and how these change with age, the literature on switching between these modalities of attention is limited within any age group. Methods : Age groups (21-30, 40-49, 50-59, 60-69 and 70+ years) were compared on their ability to switch between detecting a target in a rapid serial visual presentation (RSVP) stream and detecting a target in a visual search display. To manipulate the cost of switching, the target in the RSVP stream was either the first item in the stream (Target 1st), towards the end of the stream (Target Mid), or absent from the stream (Distractor Only). Visual search response times and accuracy were recorded. Target 1st trials behaved as no-switch trials, as attending to the remaining stream was not necessary. Target Mid and Distractor Only trials behaved as switch trials, as attending to the stream to the end was required. Results : Visual search response times (RTs) were longer on "Target Mid" and "Distractor Only" trials in comparison to "Target 1st" trials, reflecting switch-costs. Larger switch-costs were found in both the 40-49 and 60-69 years group in comparison to the 21-30 years group when switching from the Target Mid condition. Discussion : Findings warrant further exploration as to whether there are age-related changes in the ability to switch between these modalities of attention while driving. If older adults display poor performance when switching between temporal and spatial attention while driving, then the development of an intervention to preserve and improve this ability would be beneficial.

Intraoperative adaptation and visualization of preoperative risk analyses for oncologic liver surgery

NASA Astrophysics Data System (ADS)

Hansen, Christian; Schlichting, Stefan; Zidowitz, Stephan; Köhn, Alexander; Hindennach, Milo; Kleemann, Markus; Peitgen, Heinz-Otto

2008-03-01

Tumor resections from the liver are complex surgical interventions. With recent planning software, risk analyses based on individual liver anatomy can be carried out preoperatively. However, additional tumors within the liver are frequently detected during oncological interventions using intraoperative ultrasound. These tumors are not visible in preoperative data and their existence may require changes to the resection strategy. We propose a novel method that allows an intraoperative risk analysis adaptation by merging newly detected tumors with a preoperative risk analysis. To determine the exact positions and sizes of these tumors we make use of a navigated ultrasound-system. A fast communication protocol enables our application to exchange crucial data with this navigation system during an intervention. A further motivation for our work is to improve the visual presentation of a moving ultrasound plane within a complex 3D planning model including vascular systems, tumors, and organ surfaces. In case the ultrasound plane is located inside the liver, occlusion of the ultrasound plane by the planning model is an inevitable problem for the applied visualization technique. Our system allows the surgeon to focus on the ultrasound image while perceiving context-relevant planning information. To improve orientation ability and distance perception, we include additional depth cues by applying new illustrative visualization algorithms. Preliminary evaluations confirm that in case of intraoperatively detected tumors a risk analysis adaptation is beneficial for precise liver surgery. Our new GPU-based visualization approach provides the surgeon with a simultaneous visualization of planning models and navigated 2D ultrasound data while minimizing occlusion problems.

Dimension- and space-based intertrial effects in visual pop-out search: modulation by task demands for focal-attentional processing.

PubMed

Krummenacher, Joseph; Müller, Hermann J; Zehetleitner, Michael; Geyer, Thomas

2009-03-01

Two experiments compared reaction times (RTs) in visual search for singleton feature targets defined, variably across trials, in either the color or the orientation dimension. Experiment 1 required observers to simply discern target presence versus absence (simple-detection task); Experiment 2 required them to respond to a detection-irrelevant form attribute of the target (compound-search task). Experiment 1 revealed a marked dimensional intertrial effect of 34 ms for an target defined in a changed versus a repeated dimension, and an intertrial target distance effect, with an 4-ms increase in RTs (per unit of distance) as the separation of the current relative to the preceding target increased. Conversely, in Experiment 2, the dimension change effect was markedly reduced (11 ms), while the intertrial target distance effect was markedly increased (11 ms per unit of distance). The results suggest that dimension change/repetition effects are modulated by the amount of attentional focusing required by the task, with space-based attention altering the integration of dimension-specific feature contrast signals at the level of the overall-saliency map.

Selective and reusable iron(II)-based molecular sensor for the vapor-phase detection of alcohols.

PubMed

Naik, Anil D; Robeyns, Koen; Meunier, Christophe F; Léonard, Alexandre F; Rotaru, Aurelian; Tinant, Bernard; Filinchuk, Yaroslav; Su, Bao Lian; Garcia, Yann

2014-02-03

A mononuclear iron(II) neutral complex (1) is screened for sensing abilities for a wide spectrum of chemicals and to evaluate the response function toward physical perturbation like temperature and mechanical stress. Interestingly, 1 precisely detects methanol among an alcohol series. The sensing process is visually detectable, fatigue-resistant, highly selective, and reusable. The sensing ability is attributed to molecular sieving and subsequent spin-state change of iron centers, after a crystal-to-crystal transformation.

Compressive sampling by artificial neural networks for video

NASA Astrophysics Data System (ADS)

Szu, Harold; Hsu, Charles; Jenkins, Jeffrey; Reinhardt, Kitt

2011-06-01

We describe a smart surveillance strategy for handling novelty changes. Current sensors seem to keep all, redundant or not. The Human Visual System's Hubel-Wiesel (wavelet) edge detection mechanism pays attention to changes in movement, which naturally produce organized sparseness because a stagnant edge is not reported to the brain's visual cortex by retinal neurons. Sparseness is defined as an ordered set of ones (movement or not) relative to zeros that could be pseudo-orthogonal among themselves; then suited for fault tolerant storage and retrieval by means of Associative Memory (AM). The firing is sparse at the change locations. Unlike purely random sparse masks adopted in medical Compressive Sensing, these organized ones have an additional benefit of using the image changes to make retrievable graphical indexes. We coined this organized sparseness as Compressive Sampling; sensing but skipping over redundancy without altering the original image. Thus, we turn illustrate with video the survival tactics which animals that roam the Earth use daily. They acquire nothing but the space-time changes that are important to satisfy specific prey-predator relationships. We have noticed a similarity between the mathematical Compressive Sensing and this biological mechanism used for survival. We have designed a hardware implementation of the Human Visual System's Compressive Sampling scheme. To speed up further, our mixedsignal circuit design of frame differencing is built in on-chip processing hardware. A CMOS trans-conductance amplifier is designed here to generate a linear current output using a pair of differential input voltages from 2 photon detectors for change detection---one for the previous value and the other the subsequent value, ("write" synaptic weight by Hebbian outer products; "read" by inner product & pt. NL threshold) to localize and track the threat targets.

Periodic leg movements during sleep and cerebral hemodynamic changes detected by NIRS.

PubMed

Pizza, Fabio; Biallas, Martin; Wolf, Martin; Valko, Philipp O; Bassetti, Claudio L

2009-07-01

Periodic leg movements during sleep (PLMS) have been shown to be associated with changes in autonomic and hemispheric activities. Near infrared spectroscopy (NIRS) assesses hemodynamic changes linked to hemispheric/cortical activity. We applied NIRS to test whether cerebral hemodynamic alterations accompany PLMS. Three PLMS patients underwent nocturnal polysomnography coupled with cerebral NIRS. EEG correlates of PLMS were scored and NIRS data were analysed for the identification of correspondent hemodynamic changes. PLMS were constantly associated with cerebral hemodynamic fluctuations that showed greater amplitude when associated to changes in EEG and were present also in absence of any visually detectable arousal or A phase in the EEG. This is the first study documenting cerebral hemodynamic changes linked to PLMS. The clinical relevance of these observations remains to be determined.

Developmental Test of Visual-Motor Integration (VMI): An Effective Outcome Measure for Handwriting Interventions for Kindergarten, First-Grade, and Second-Grade Students?

PubMed

Pfeiffer, Beth; Moskowitz, Beverly; Paoletti, Andrew; Brusilovskiy, Eugene; Zylstra, Sheryl Eckberg; Murray, Tammy

2015-01-01

We determined whether a widely used assessment of visual-motor skills, the Beery-Buktenica Developmental Test of Visual-Motor Integration (VMI), is appropriate for use as an outcome measure for handwriting interventions. A two-group pretest-posttest design was used with 207 kindergarten, first-grade, and second-grade students. Two well-established handwriting measures and the VMI were administered pre- and postintervention. The intervention group participated in the Size Matters Handwriting Program for 40 sessions, and the control group received standard instruction. Paired and independent-samples t tests were used to analyze group differences. The intervention group demonstrated significant improvements on the handwriting measures, with change scores having mostly large effect sizes. We found no significant difference in change scores on the VMI, t(202)=1.19, p=.23. Results of this study suggest that the VMI may not detect changes in handwriting related to occupational therapy intervention. Copyright © 2015 by the American Occupational Therapy Association, Inc.

Early changes in coronary artery wall structure detected by microcomputed tomography in experimental hypercholesterolemia.

PubMed

Zhu, Xiang-Yang; Bentley, Michael D; Chade, Alejandro R; Ritman, Erik L; Lerman, Amir; Lerman, Lilach O

2007-09-01

Changes in the structure of the artery wall commence shortly after exposure to cardiovascular risk factors, such as hypercholesterolemia (HC), but may be difficult to detect. The ability to study vascular wall structure could be helpful in evaluation of the factors that instigate atherosclerosis and its pathomechanisms. The present study tested the hypothesis that early morphological changes in coronary arteries of hypercholesterolemic (HC) pigs can be detected using the novel X-ray contrast agent OsO(4) and three-dimensional micro-computed tomography (CT). Two groups of pigs were studied after they were fed a normal or an HC (2% cholesterol) diet for 12 wk. Hearts were harvested, coronary arteries were injected with 1% OsO(4) solution, and cardiac samples (6-mum-thick) were scanned by micro-CT. Layers of the epicardial coronary artery wall, early lesions, and perivascular OsO(4) accumulation were determined. Leakage of OsO(4) from myocardial microvessels was used to assess vascular permeability, which was correlated with immunoreactivity of vascular endothelial growth factor in corresponding histological cross sections. OsO(4) enhanced the visualization of coronary artery wall layers and facilitated detection of early lesions in HC in longitudinal tomographic sections of vascular segments. Increased density of perivascular OsO(4) in HC was correlated with increased vascular endothelial growth factor expression and suggested increased microvascular permeability. The use of OsO(4) as a contrast agent in micro-CT allows three-dimensional visualization of coronary artery wall structure, early lesion formation, and changes in vascular permeability. Therefore, this technique can be a useful tool in atherosclerosis research.

Rapid Change Detection Algorithm for Disaster Management

NASA Astrophysics Data System (ADS)

Michel, U.; Thunig, H.; Ehlers, M.; Reinartz, P.

2012-07-01

This paper focuses on change detection applications in areas where catastrophic events took place which resulted in rapid destruction especially of manmade objects. Standard methods for automated change detection prove not to be sufficient; therefore a new method was developed and tested. The presented method allows a fast detection and visualization of change in areas of crisis or catastrophes. While often new methods of remote sensing are developed without user oriented aspects, organizations and authorities are not able to use these methods because of absence of remote sensing know how. Therefore a semi-automated procedure was developed. Within a transferable framework, the developed algorithm can be implemented for a set of remote sensing data among different investigation areas. Several case studies are the base for the retrieved results. Within a coarse dividing into statistical parts and the segmentation in meaningful objects, the framework is able to deal with different types of change. By means of an elaborated Temporal Change Index (TCI) only panchromatic datasets are used to extract areas which are destroyed, areas which were not affected and in addition areas where rebuilding has already started.

Turbidity interferes with foraging success of visual but not chemosensory predators

PubMed Central

Smee, Delbert L.

2015-01-01

Predation can significantly affect prey populations and communities, but predator effects can be attenuated when abiotic conditions interfere with foraging activities. In estuarine communities, turbidity can affect species richness and abundance and is changing in many areas because of coastal development. Many fish species are less efficient foragers in turbid waters, and previous research revealed that in elevated turbidity, fish are less abundant whereas crabs and shrimp are more abundant. We hypothesized that turbidity altered predatory interactions in estuaries by interfering with visually-foraging predators and prey but not with organisms relying on chemoreception. We measured the effects of turbidity on the predation rates of two model predators: a visual predator (pinfish, Lagodon rhomboides) and a chemosensory predator (blue crabs, Callinectes sapidus) in clear and turbid water (0 and ∼100 nephelometric turbidity units). Feeding assays were conducted with two prey items, mud crabs (Panopeus spp.) that rely heavily on chemoreception to detect predators, and brown shrimp (Farfantepenaus aztecus) that use both chemical and visual cues for predator detection. Because turbidity reduced pinfish foraging on both mud crabs and shrimp, the changes in predation rates are likely driven by turbidity attenuating fish foraging ability and not by affecting prey vulnerability to fish consumers. Blue crab foraging was unaffected by turbidity, and blue crabs were able to successfully consume nearly all mud crab and shrimp prey. Turbidity can influence predator–prey interactions by reducing the feeding efficiency of visual predators, providing a competitive advantage to chemosensory predators, and altering top-down control in food webs. PMID:26401444

Turbidity interferes with foraging success of visual but not chemosensory predators.

PubMed

Lunt, Jessica; Smee, Delbert L

2015-01-01

Predation can significantly affect prey populations and communities, but predator effects can be attenuated when abiotic conditions interfere with foraging activities. In estuarine communities, turbidity can affect species richness and abundance and is changing in many areas because of coastal development. Many fish species are less efficient foragers in turbid waters, and previous research revealed that in elevated turbidity, fish are less abundant whereas crabs and shrimp are more abundant. We hypothesized that turbidity altered predatory interactions in estuaries by interfering with visually-foraging predators and prey but not with organisms relying on chemoreception. We measured the effects of turbidity on the predation rates of two model predators: a visual predator (pinfish, Lagodon rhomboides) and a chemosensory predator (blue crabs, Callinectes sapidus) in clear and turbid water (0 and ∼100 nephelometric turbidity units). Feeding assays were conducted with two prey items, mud crabs (Panopeus spp.) that rely heavily on chemoreception to detect predators, and brown shrimp (Farfantepenaus aztecus) that use both chemical and visual cues for predator detection. Because turbidity reduced pinfish foraging on both mud crabs and shrimp, the changes in predation rates are likely driven by turbidity attenuating fish foraging ability and not by affecting prey vulnerability to fish consumers. Blue crab foraging was unaffected by turbidity, and blue crabs were able to successfully consume nearly all mud crab and shrimp prey. Turbidity can influence predator-prey interactions by reducing the feeding efficiency of visual predators, providing a competitive advantage to chemosensory predators, and altering top-down control in food webs.

Activity-dependent regulation of NMDAR1 immunoreactivity in the developing visual cortex.

PubMed

Catalano, S M; Chang, C K; Shatz, C J

1997-11-01

NMDA receptors have been implicated in activity-dependent synaptic plasticity in the developing visual cortex. We examined the distribution of immunocytochemically detectable NMDAR1 in visual cortex of cats and ferrets from late embryonic ages to adulthood. Cortical neurons are initially highly immunostained. This level declines gradually over development, with the notable exception of cortical layers 2/3, where levels of NMDAR1 immunostaining remain high into adulthood. Within layer 4, the decline in NMDAR1 immunostaining to adult levels coincides with the completion of ocular dominance column formation and the end of the critical period for layer 4. To determine whether NMDAR1 immunoreactivity is regulated by retinal activity, animals were dark-reared or retinal activity was completely blocked in one eye with tetrodotoxin (TTX). Dark-rearing does not cause detectable changes in NMDAR1 immunoreactivity. However, 2 weeks of monocular TTX administration decreases NMDAR1 immunoreactivity in layer 4 of the columns of the blocked eye. Thus, high levels of NMDAR1 immunostaining within the visual cortex are temporally correlated with ocular dominance column formation and developmental plasticity; the persistence of staining in layers 2/3 also correlates with the physiological plasticity present in these layers in the adult. In addition, visual experience is not required for the developmental changes in the laminar pattern of NMDAR1 levels, but the presence of high levels of NMDAR1 in layer 4 during the critical period does require retinal activity. These observations are consistent with a central role for NMDA receptors in promoting and ultimately limiting synaptic rearrangements in the developing neocortex.

Probe Scanning Support System by a Parallel Mechanism for Robotic Echography

NASA Astrophysics Data System (ADS)

Aoki, Yusuke; Kaneko, Kenta; Oyamada, Masami; Takachi, Yuuki; Masuda, Kohji

We propose a probe scanning support system based on force/visual servoing control for robotic echography. First, we have designed and formulated its inverse kinematics the construction of mechanism. Next, we have developed a scanning method of the ultrasound probe on body surface to construct visual servo system based on acquired echogram by the standalone medical robot to move the ultrasound probe on patient abdomen in three-dimension. The visual servo system detects local change of brightness in time series echogram, which is stabilized the position of the probe by conventional force servo system in the robot, to compensate not only periodical respiration motion but also body motion. Then we integrated control method of the visual servo with the force servo as a hybrid control in both of position and force. To confirm the ability to apply for actual abdomen, we experimented the total system to follow the gallbladder as a moving target to keep its position in the echogram by minimizing variation of reaction force on abdomen. As the result, the system has a potential to be applied to automatic detection of human internal organ.

Evaluation of hemifield sector analysis protocol in multifocal visual evoked potential objective perimetry for the diagnosis and early detection of glaucomatous field defects.

PubMed

Mousa, Mohammad F; Cubbidge, Robert P; Al-Mansouri, Fatima; Bener, Abdulbari

2014-02-01

Multifocal visual evoked potential (mfVEP) is a newly introduced method used for objective visual field assessment. Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard automated perimetry (SAP) visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma. Three groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey field analyzer (HFA) test 24-2 and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the hemifield sector analysis (HSA) protocol. Analysis of the HFA was done using the standard grading system. Analysis of mfVEP results showed that there was a statistically significant difference between the three groups in the mean signal to noise ratio (ANOVA test, p < 0.001 with a 95% confidence interval). The difference between superior and inferior hemispheres in all subjects were statistically significant in the glaucoma patient group in all 11 sectors (t-test, p < 0.001), partially significant in 5 / 11 (t-test, p < 0.01), and no statistical difference in most sectors of the normal group (1 / 11 sectors was significant, t-test, p < 0.9). Sensitivity and specificity of the HSA protocol in detecting glaucoma was 97% and 86%, respectively, and for glaucoma suspect patients the values were 89% and 79%, respectively. The new HSA protocol used in the mfVEP testing can be applied to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss.

Evaluation of Hemifield Sector Analysis Protocol in Multifocal Visual Evoked Potential Objective Perimetry for the Diagnosis and Early Detection of Glaucomatous Field Defects

PubMed Central

Mousa, Mohammad F.; Cubbidge, Robert P.; Al-Mansouri, Fatima

2014-01-01

Purpose Multifocal visual evoked potential (mfVEP) is a newly introduced method used for objective visual field assessment. Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard automated perimetry (SAP) visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma. Methods Three groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey field analyzer (HFA) test 24-2 and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the hemifield sector analysis (HSA) protocol. Analysis of the HFA was done using the standard grading system. Results Analysis of mfVEP results showed that there was a statistically significant difference between the three groups in the mean signal to noise ratio (ANOVA test, p < 0.001 with a 95% confidence interval). The difference between superior and inferior hemispheres in all subjects were statistically significant in the glaucoma patient group in all 11 sectors (t-test, p < 0.001), partially significant in 5 / 11 (t-test, p < 0.01), and no statistical difference in most sectors of the normal group (1 / 11 sectors was significant, t-test, p < 0.9). Sensitivity and specificity of the HSA protocol in detecting glaucoma was 97% and 86%, respectively, and for glaucoma suspect patients the values were 89% and 79%, respectively. Conclusions The new HSA protocol used in the mfVEP testing can be applied to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss. PMID:24511212

Visual Analytics approach for Lightning data analysis and cell nowcasting

NASA Astrophysics Data System (ADS)

Peters, Stefan; Meng, Liqiu; Betz, Hans-Dieter

2013-04-01

Thunderstorms and their ground effects, such as flash floods, hail, lightning, strong wind and tornadoes, are responsible for most weather damages (Bonelli & Marcacci 2008). Thus to understand, identify, track and predict lightning cells is essential. An important aspect for decision makers is an appropriate visualization of weather analysis results including the representation of dynamic lightning cells. This work focuses on the visual analysis of lightning data and lightning cell nowcasting which aim to detect and understanding spatial-temporal patterns of moving thunderstorms. Lightnings are described by 3D coordinates and the exact occurrence time of lightnings. The three-dimensionally resolved total lightning data used in our experiment are provided by the European lightning detection network LINET (Betz et al. 2009). In all previous works, lightning point data, detected lightning cells and derived cell tracks are visualized in 2D. Lightning cells are either displayed as 2D convex hulls with or without the underlying lightning point data. Due to recent improvements of lightning data detection and accuracy, there is a growing demand on multidimensional and interactive visualization in particular for decision makers. In a first step lightning cells are identified and tracked. Then an interactive graphic user interface (GUI) is developed to investigate the dynamics of the lightning cells: e.g. changes of cell density, location, extension as well as merging and splitting behavior in 3D over time. In particular a space time cube approach is highlighted along with statistical analysis. Furthermore a lightning cell nowcasting is conducted and visualized. The idea thereby is to predict the following cell features for the next 10-60 minutes including location, centre, extension, density, area, volume, lifetime and cell feature probabilities. The main focus will be set to a suitable interactive visualization of the predicted featured within the GUI. The developed visual exploring tool for the purpose of supporting decision making is investigated for two determined user groups: lightning experts and interested lay public. Betz HD, Schmidt K, Oettinger WP (2009) LINET - An International VLF/LF Lightning Detection Network in Europe. In: Betz HD, Schumann U, Laroche P (eds) Lightning: Principles, Instruments and Applications. Springer Netherlands, Dordrecht, pp 115-140 Bonelli P, Marcacci P (2008) Thunderstorm nowcasting by means of lightning and radar data: algorithms and applications in northern Italy. Nat. Hazards Earth Syst. Sci 8(5):1187-1198

Fluorescent probes sensitive to changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during atherosclerosis

NASA Astrophysics Data System (ADS)

Posokhov, Yevgen

2016-09-01

Environment-sensitive fluorescent probes were used for the spectroscopic visualization of pathological changes in human platelet membranes during cerebral atherosclerosis. It has been estimated that the ratiometric probes 2-(2‧-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazole and 2-phenyl-phenanthr[9,10]oxazole can detect changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during the disease.

Thin-plate spline (TPS) graphical analysis of the mandible on cephalometric radiographs.

PubMed

Chang, H P; Liu, P H; Chang, H F; Chang, C H

2002-03-01

We describe two cases of Class III malocclusion with and without orthodontic treatment. A thin-plate spline (TPS) analysis of lateral cephalometric radiographs was used to visualize transformations of the mandible. The actual sites of mandibular skeletal change are not detectable with conventional cephalometric analysis. These case analyses indicate that specific patterns of mandibular transformation are associated with Class III malocclusion with or without orthopaedic therapy, and visualization of these deformations is feasible using TPS graphical analysis.

The Efficiency of a Visual Skills Training Program on Visual Search Performance

PubMed Central

Krzepota, Justyna; Zwierko, Teresa; Puchalska-Niedbał, Lidia; Markiewicz, Mikołaj; Florkiewicz, Beata; Lubiński, Wojciech

2015-01-01

In this study, we conducted an experiment in which we analyzed the possibilities to develop visual skills by specifically targeted training of visual search. The aim of our study was to investigate whether, for how long and to what extent a training program for visual functions could improve visual search. The study involved 24 healthy students from the Szczecin University who were divided into two groups: experimental (12) and control (12). In addition to regular sports and recreational activities of the curriculum, the subjects of the experimental group also participated in 8-week long training with visual functions, 3 times a week for 45 min. The Signal Test of the Vienna Test System was performed four times: before entering the study, after first 4 weeks of the experiment, immediately after its completion and 4 weeks after the study terminated. The results of this experiment proved that an 8-week long perceptual training program significantly differentiated the plot of visual detecting time. For the visual detecting time changes, the first factor, Group, was significant as a main effect (F(1,22)=6.49, p<0.05) as well as the second factor, Training (F(3,66)=5.06, p<0.01). The interaction between the two factors (Group vs. Training) of perceptual training was F(3,66)=6.82 (p<0.001). Similarly, for the number of correct reactions, there was a main effect of a Group factor (F(1,22)=23.40, p<0.001), a main effect of a Training factor (F(3,66)=11.60, p<0.001) and a significant interaction between factors (Group vs. Training) (F(3,66)=10.33, p<0.001). Our study suggests that 8-week training of visual functions can improve visual search performance. PMID:26240666

Early detection of glaucoma using fully automated disparity analysis of the optic nerve head (ONH) from stereo fundus images

NASA Astrophysics Data System (ADS)

Sharma, Archie; Corona, Enrique; Mitra, Sunanda; Nutter, Brian S.

2006-03-01

Early detection of structural damage to the optic nerve head (ONH) is critical in diagnosis of glaucoma, because such glaucomatous damage precedes clinically identifiable visual loss. Early detection of glaucoma can prevent progression of the disease and consequent loss of vision. Traditional early detection techniques involve observing changes in the ONH through an ophthalmoscope. Stereo fundus photography is also routinely used to detect subtle changes in the ONH. However, clinical evaluation of stereo fundus photographs suffers from inter- and intra-subject variability. Even the Heidelberg Retina Tomograph (HRT) has not been found to be sufficiently sensitive for early detection. A semi-automated algorithm for quantitative representation of the optic disc and cup contours by computing accumulated disparities in the disc and cup regions from stereo fundus image pairs has already been developed using advanced digital image analysis methodologies. A 3-D visualization of the disc and cup is achieved assuming camera geometry. High correlation among computer-generated and manually segmented cup to disc ratios in a longitudinal study involving 159 stereo fundus image pairs has already been demonstrated. However, clinical usefulness of the proposed technique can only be tested by a fully automated algorithm. In this paper, we present a fully automated algorithm for segmentation of optic cup and disc contours from corresponding stereo disparity information. Because this technique does not involve human intervention, it eliminates subjective variability encountered in currently used clinical methods and provides ophthalmologists with a cost-effective and quantitative method for detection of ONH structural damage for early detection of glaucoma.

Does working memory load facilitate target detection?

PubMed

Fruchtman-Steinbok, Tom; Kessler, Yoav

2016-02-01

Previous studies demonstrated that increasing working memory (WM) load delays performance of a concurrent task, by distracting attention and thus interfering with encoding and maintenance processes. The present study used a version of the change detection task with a target detection requirement during the retention interval. In contrast to the above prediction, target detection was faster following a larger set-size, specifically when presented shortly after the memory array (up to 400 ms). The effect of set-size on target detection was also evident when no memory retention was required. The set-size effect was also found using different modalities. Moreover, it was only observed when the memory array was presented simultaneously, but not sequentially. These results were explained by increased phasic alertness exerted by the larger visual display. The present study offers new evidence of ongoing attentional processes in the commonly-used change detection paradigm. Copyright © 2015 Elsevier B.V. All rights reserved.

Early detection of glaucoma by means of a novel 3D computer‐automated visual field test

PubMed Central

Nazemi, Paul P; Fink, Wolfgang; Sadun, Alfredo A; Francis, Brian; Minckler, Donald

2007-01-01

Purpose A recently devised 3D computer‐automated threshold Amsler grid test was used to identify early and distinctive defects in people with suspected glaucoma. Further, the location, shape and depth of these field defects were characterised. Finally, the visual fields were compared with those obtained by standard automated perimetry. Patients and methods Glaucoma suspects were defined as those having elevated intraocular pressure (>21 mm Hg) or cup‐to‐disc ratio of >0.5. 33 patients and 66 eyes with risk factors for glaucoma were examined. 15 patients and 23 eyes with no risk factors were tested as controls. The recently developed 3D computer‐automated threshold Amsler grid test was used. The test exhibits a grid on a computer screen at a preselected greyscale and angular resolution, and allows patients to trace those areas on the grid that are missing in their visual field using a touch screen. The 5‐minute test required that the patients repeatedly outline scotomas on a touch screen with varied displays of contrast while maintaining their gaze on a central fixation marker. A 3D depiction of the visual field defects was then obtained that was further characterised by the location, shape and depth of the scotomas. The exam was repeated three times per eye. The results were compared to Humphrey visual field tests (ie, achromatic standard or SITA standard 30‐2 or 24‐2). Results In this pilot study 79% of the eyes tested in the glaucoma‐suspect group repeatedly demonstrated visual field loss with the 3D perimetry. The 3D depictions of visual field loss associated with these risk factors were all characteristic of or compatible with glaucoma. 71% of the eyes demonstrated arcuate defects or a nasal step. Constricted visual fields were shown in 29% of the eyes. No visual field changes were detected in the control group. Conclusions The 3D computer‐automated threshold Amsler grid test may demonstrate visual field abnormalities characteristic of glaucoma in glaucoma suspects with normal achromatic Humphrey visual field testing. This test may be used as a screening tool for the early detection of glaucoma. PMID:17504855

Introduction to the Special Issue on Visual Working Memory

PubMed Central

Wolfe, Jeremy M

2014-01-01

Objects are not represented individually in visual working memory (VWM), but in relation to the contextual information provided by other memorized objects. We studied whether the contextual information provided by the spatial configuration of all memorized objects is viewpoint-dependent. We ran two experiments asking participants to detect changes in locations between memory and probe for one object highlighted in the probe image. We manipulated the changes in viewpoint between memory and probe (Exp. 1: 0°, 30°, 60°; Exp. 2: 0°, 60°), as well as the spatial configuration visible in the probe image (Exp. 1: full configuration, partial configuration; Exp. 2: full configuration, no configuration). Location change detection was higher with the full spatial configuration than with the partial configuration or with no spatial configuration at viewpoint changes of 0°, thus replicating previous findings on the nonindependent representations of individual objects in VWM. Most importantly, the effect of spatial configurations decreased with increasing viewpoint changes, suggesting a viewpoint-dependent representation of contextual information in VWM. We discuss these findings within the context of this special issue, in particular whether research performed within the slots-versus-resources debate and research on the effects of contextual information might focus on two different storage systems within VWM. PMID:25341647

Change Detection by Rhesus Monkeys (Macaca mulatta) and Pigeons (Columba livia)

PubMed Central

Elmore, L. Caitlin; Magnotti, John F.; Katz, Jeffrey S.; Wright, Anthony A.

2012-01-01

Two monkeys learned a color change-detection task where two colored circles (selected from a 4-color set) were presented on a 4×4 invisible matrix. Following a delay, the correct response was to touch the changed colored circle. The monkeys' learning, color transfer, and delay transfer were compared to a similar experiment with pigeons. Monkeys, like pigeons, showed full transfer to four novel colors, and to delays as long as 6.4 s, suggesting they remembered the colors as opposed to perceptual based attentional capture process that may work at very short delays. The monkeys and pigeons were further tested to compare transfer to other dimensions. Monkeys transferred to shape and location changes, unlike the pigeons, but neither species transferred to size changes. Thus, monkeys were less restricted in their domain to detect change than pigeons, but both species learned the basic task and appear suitable for comparative studies of visual short-term memory. PMID:22428982

Augmented Citizen Science for Environmental Monitoring and Education

NASA Astrophysics Data System (ADS)

Albers, B.; de Lange, N.; Xu, S.

2017-09-01

Environmental monitoring and ecological studies detect and visualize changes of the environment over time. Some agencies are committed to document the development of conservation and status of geotopes and geosites, which is time-consuming and cost-intensive. Citizen science and crowd sourcing are modern approaches to collect data and at the same time to raise user awareness for environmental changes. Citizen scientists can take photographs of point of interests (POI) with smartphones and the PAN App, which is presented in this article. The user is navigated to a specific point and is then guided with an augmented reality approach to take a photo in a specific direction. The collected photographs are processed to time-lapse videos to visualize environmental changes. Users and experts in environmental agencies can use this data for long-term documentation.

Real-time biscuit tile image segmentation method based on edge detection.

PubMed

Matić, Tomislav; Aleksi, Ivan; Hocenski, Željko; Kraus, Dieter

2018-05-01

In this paper we propose a novel real-time Biscuit Tile Segmentation (BTS) method for images from ceramic tile production line. BTS method is based on signal change detection and contour tracing with a main goal of separating tile pixels from background in images captured on the production line. Usually, human operators are visually inspecting and classifying produced ceramic tiles. Computer vision and image processing techniques can automate visual inspection process if they fulfill real-time requirements. Important step in this process is a real-time tile pixels segmentation. BTS method is implemented for parallel execution on a GPU device to satisfy the real-time constraints of tile production line. BTS method outperforms 2D threshold-based methods, 1D edge detection methods and contour-based methods. Proposed BTS method is in use in the biscuit tile production line. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Video content parsing based on combined audio and visual information

NASA Astrophysics Data System (ADS)

Zhang, Tong; Kuo, C.-C. Jay

1999-08-01

While previous research on audiovisual data segmentation and indexing primarily focuses on the pictorial part, significant clues contained in the accompanying audio flow are often ignored. A fully functional system for video content parsing can be achieved more successfully through a proper combination of audio and visual information. By investigating the data structure of different video types, we present tools for both audio and visual content analysis and a scheme for video segmentation and annotation in this research. In the proposed system, video data are segmented into audio scenes and visual shots by detecting abrupt changes in audio and visual features, respectively. Then, the audio scene is categorized and indexed as one of the basic audio types while a visual shot is presented by keyframes and associate image features. An index table is then generated automatically for each video clip based on the integration of outputs from audio and visual analysis. It is shown that the proposed system provides satisfying video indexing results.

Imprinting modulates processing of visual information in the visual wulst of chicks.

PubMed

Maekawa, Fumihiko; Komine, Okiru; Sato, Katsushige; Kanamatsu, Tomoyuki; Uchimura, Motoaki; Tanaka, Kohichi; Ohki-Hamazaki, Hiroko

2006-11-14

Imprinting behavior is one form of learning and memory in precocial birds. With the aim of elucidating of the neural basis for visual imprinting, we focused on visual information processing. A lesion in the visual wulst, which is similar functionally to the mammalian visual cortex, caused anterograde amnesia in visual imprinting behavior. Since the color of an object was one of the important cues for imprinting, we investigated color information processing in the visual wulst. Intrinsic optical signals from the visual wulst were detected in the early posthatch period and the peak regions of responses to red, green, and blue were spatially organized from the caudal to the nasal regions in dark-reared chicks. This spatial representation of color recognition showed plastic changes, and the response pattern along the antero-posterior axis of the visual wulst altered according to the color the chick was imprinted to. These results indicate that the thalamofugal pathway is critical for learning the imprinting stimulus and that the visual wulst shows learning-related plasticity and may relay processed visual information to indicate the color of the imprint stimulus to the memory storage region, e.g., the intermediate medial mesopallium.

Imprinting modulates processing of visual information in the visual wulst of chicks

PubMed Central

Maekawa, Fumihiko; Komine, Okiru; Sato, Katsushige; Kanamatsu, Tomoyuki; Uchimura, Motoaki; Tanaka, Kohichi; Ohki-Hamazaki, Hiroko

2006-01-01

Background Imprinting behavior is one form of learning and memory in precocial birds. With the aim of elucidating of the neural basis for visual imprinting, we focused on visual information processing. Results A lesion in the visual wulst, which is similar functionally to the mammalian visual cortex, caused anterograde amnesia in visual imprinting behavior. Since the color of an object was one of the important cues for imprinting, we investigated color information processing in the visual wulst. Intrinsic optical signals from the visual wulst were detected in the early posthatch period and the peak regions of responses to red, green, and blue were spatially organized from the caudal to the nasal regions in dark-reared chicks. This spatial representation of color recognition showed plastic changes, and the response pattern along the antero-posterior axis of the visual wulst altered according to the color the chick was imprinted to. Conclusion These results indicate that the thalamofugal pathway is critical for learning the imprinting stimulus and that the visual wulst shows learning-related plasticity and may relay processed visual information to indicate the color of the imprint stimulus to the memory storage region, e.g., the intermediate medial mesopallium. PMID:17101060

What visual information is used for stereoscopic depth displacement discrimination?

PubMed

Nefs, Harold T; Harris, Julie M

2010-01-01

There are two ways to detect a displacement in stereoscopic depth, namely by monitoring the change in disparity over time (CDOT) or by monitoring the interocular velocity difference (IOVD). Though previous studies have attempted to understand which cue is most significant for the visual system, none has designed stimuli that provide a comparison in terms of relative efficiency between them. Here we used two-frame motion and random-dot noise to deliver equivalent strengths of CDOT and IOVD information to the visual system. Using three kinds of random-dot stimuli, we were able to isolate CDOT or IOVD or deliver both simultaneously. The proportion of dots delivering CDOT or IOVD signals could be varied, and we defined the discrimination threshold as the proportion needed to detect the direction of displacement (towards or away). Thresholds were similar for stimuli containing CDOT only, and containing both CDOT and IOVD, but only one participant was able to consistently perceive the displacement for stimuli containing only IOVD. We also investigated the effect of disparity pedestals on discrimination. Performance was best when the displacement crossed the reference plane, but was not significantly different for stimuli containing CDOT only and those containing both CDOT and IOVD. When stimuli are specifically designed to provide equivalent two-frame motion or disparity-change, few participants can reliably detect displacement when IOVD is the only cue. This challenges the notion that IOVD is involved in the discrimination of direction of displacement in two-frame motion displays.

Visual and surface plasmon resonance sensor for zirconium based on zirconium-induced aggregation of adenosine triphosphate-stabilized gold nanoparticles.

PubMed

Qi, Wenjing; Zhao, Jianming; Zhang, Wei; Liu, Zhongyuan; Xu, Min; Anjum, Saima; Majeed, Saadat; Xu, Guobao

2013-07-17

Owing to its high affinity with phosphate, Zr(IV) can induce the aggregation of adenosine 5'-triphosphate (ATP)-stabilized AuNPs, leading to the change of surface plasmon resonance (SPR) absorption spectra and color of ATP-stabilized AuNP solutions. Based on these phenomena, visual and SPR sensors for Zr(IV) have been developed for the first time. The A(660 nm)/A(518 nm) values of ATP-stabilized AuNPs in SPR absorption spectra increase linearly with the concentrations of Zr(IV) from 0.5 μM to 100 μM (r=0.9971) with a detection limit of 95 nM. A visual Zr(IV) detection is achieved with a detection limit of 30 μM. The sensor shows excellent selectivity against other metal ions, such as Cu(2+), Fe(3+), Cd(2+), and Pb(2+). The recoveries for the detection of 5 μM, 10 μM, 25 μM and 75 μM Zr(IV) in lake water samples are 96.0%, 97.0%, 95.6% and 102.4%, respectively. The recoveries of the proposed SPR method are comparable with those of ICP-OES method. Copyright © 2013 Elsevier B.V. All rights reserved.

Perceptual learning effect on decision and confidence thresholds.

PubMed

Solovey, Guillermo; Shalom, Diego; Pérez-Schuster, Verónica; Sigman, Mariano

2016-10-01

Practice can enhance of perceptual sensitivity, a well-known phenomenon called perceptual learning. However, the effect of practice on subjective perception has received little attention. We approach this problem from a visual psychophysics and computational modeling perspective. In a sequence of visual search experiments, subjects significantly increased the ability to detect a "trained target". Before and after training, subjects performed two psychophysical protocols that parametrically vary the visibility of the "trained target": an attentional blink and a visual masking task. We found that confidence increased after learning only in the attentional blink task. Despite large differences in some observables and task settings, we identify common mechanisms for decision-making and confidence. Specifically, our behavioral results and computational model suggest that perceptual ability is independent of processing time, indicating that changes in early cortical representations are effective, and learning changes decision criteria to convey choice and confidence. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of early activator treatment in patients with class II malocclusion evaluated by thin-plate spline analysis.

PubMed

Lux, C J; Rübel, J; Starke, J; Conradt, C; Stellzig, P A; Komposch, P G

2001-04-01

The aim of the present longitudinal cephalometric study was to evaluate the dentofacial shape changes induced by activator treatment between 9.5 and 11.5 years in male Class II patients. For a rigorous morphometric analysis, a thin-plate spline analysis was performed to assess and visualize dental and skeletal craniofacial changes. Twenty male patients with a skeletal Class II malrelationship and increased overjet who had been treated at the University of Heidelberg with a modified Andresen-Häupl-type activator were compared with a control group of 15 untreated male subjects of the Belfast Growth Study. The shape changes for each group were visualized on thin-plate splines with one spline comprising all 13 landmarks to show all the craniofacial shape changes, including skeletal and dento-alveolar reactions, and a second spline based on 7 landmarks to visualize only the skeletal changes. In the activator group, the grid deformation of the total spline pointed to a strong activator-induced reduction of the overjet that was caused both by a tipping of the incisors and by a moderation of sagittal discrepancies, particularly a slight advancement of the mandible. In contrast with this, in the control group, only slight localized shape changes could be detected. Both in the 7- and 13-landmark configurations, the shape changes between the groups differed significantly at P < .001. In the present study, the morphometric approach of thin-plate spline analysis turned out to be a useful morphometric supplement to conventional cephalometrics because the complex patterns of shape change could be suggestively visualized.

Short-term plasticity in auditory cognition.

PubMed

Jääskeläinen, Iiro P; Ahveninen, Jyrki; Belliveau, John W; Raij, Tommi; Sams, Mikko

2007-12-01

Converging lines of evidence suggest that auditory system short-term plasticity can enable several perceptual and cognitive functions that have been previously considered as relatively distinct phenomena. Here we review recent findings suggesting that auditory stimulation, auditory selective attention and cross-modal effects of visual stimulation each cause transient excitatory and (surround) inhibitory modulations in the auditory cortex. These modulations might adaptively tune hierarchically organized sound feature maps of the auditory cortex (e.g. tonotopy), thus filtering relevant sounds during rapidly changing environmental and task demands. This could support auditory sensory memory, pre-attentive detection of sound novelty, enhanced perception during selective attention, influence of visual processing on auditory perception and longer-term plastic changes associated with perceptual learning.

The effect of increased monitoring load on vigilance performance using a simulated radar display.

DOT National Transportation Integrated Search

1977-07-01

The present study examined the extent to which level of target density influences the ability to sustain attention to a complex monitoring task requiring only a detection response to simple stimulus change. The visual display was designed to approxim...

Blind source separation in retinal videos

NASA Astrophysics Data System (ADS)

Barriga, Eduardo S.; Truitt, Paul W.; Pattichis, Marios S.; Tüso, Dan; Kwon, Young H.; Kardon, Randy H.; Soliz, Peter

2003-05-01

An optical imaging device of retina function (OID-RF) has been developed to measure changes in blood oxygen saturation due to neural activity resulting from visual stimulation of the photoreceptors in the human retina. The video data that are collected represent a mixture of the functional signal in response to the retinal activation and other signals from undetermined physiological activity. Measured changes in reflectance in response to the visual stimulus are on the order of 0.1% to 1.0% of the total reflected intensity level which makes the functional signal difficult to detect by standard methods since it is masked by the other signals that are present. In this paper, we apply principal component analysis (PCA), blind source separation (BSS), using Extended Spatial Decorrelation (ESD) and independent component analysis (ICA) using the Fast-ICA algorithm to extract the functional signal from the retinal videos. The results revealed that the functional signal in a stimulated retina can be detected through the application of some of these techniques.

A comparative study of the usefulness of color vision, photostress recovery time, and visual evoked potential tests in early detection of ocular toxicity from hydroxychloroquine.

PubMed

Heravian, Javad; Saghafi, Massoud; Shoeibi, Naser; Hassanzadeh, Samira; Shakeri, Mohammad Taghi; Sharepoor, Maria

2011-08-01

Ocular toxicity from hydroxychloroquine (HCQ) is rare, but its potential permanence and severity makes it imperative to employ measures and screening protocols to minimize its occurrence. This study was performed to assess the usefulness of color vision, photo stress recovery time (PSRT), and visual evoked potentials (VEP) in early detection of ocular toxicity of HCQ, in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). 86 patients were included in the study and divided into three groups: (1) with history of HCQ use: interventional 1 (Int.1) without fundoscopic changes and Int.2 with fundoscopic changes; and (2) without history of HCQ use, as control. Visual field, color vision, PSRT and VEP results were recorded for all patients and the effect of age, disease duration, treatment duration and cumulative dose of HCQ on each test was assessed in each group. There was a significant relationship among PSRT and age, treatment duration, cumulative dose of HCQ and disease duration (P<0.001 for all). Color vision was normal in all the cases. P100 amplitude was not different between the three groups (P=0.846), but P100 latency was significantly different (P=0.025) and for Int.2 it was greater than the others. The percentage of abnormal visual fields for Int.2 was more than Int.1 and control groups (P=0.002 and P=0.005 respectively), but Int.1 and control groups were not significantly different (P>0.50). In the early stages of maculopathy, P100 latencies of VEP and PSRT are useful predictors of HCQ ocular toxicity. In patients without ocular symptoms and fundoscopic changes, the P100 latency of VEP predicts more precisely than the others.

Hypervelocity Technology Escape System Concepts. Volume 1. Development and Evaluation

DTIC Science & Technology

1988-07-01

airplane escape systems. These include separation at high dynamic pressure, stability, impact attenuation , crew member accelerations, adequate...changes (TTS; 0 Shock attenuator design PTS) 0 Restraint system design * Limb flail * Non-auditory changes (gag, dec. visual acuity) * Reduced psycho-motor...detected by ultrasonic technique. The DCS symptoms may not appear until at slightly lower total pressures (8 N psia - 9 pals). Since the pressurization

Stress Analyzer

NASA Technical Reports Server (NTRS)

1990-01-01

SPATE 900 Dynamic Stress Analyzer is an acronym for Stress Pattern Analysis by Thermal Emission. It detects stress-induced temperature changes in a structure and indicates the degree of stress. Ometron, Inc.'s SPATE 9000 consists of a scan unit and a data display. The scan unit contains an infrared channel focused on the test structure to collect thermal radiation, and a visual channel used to set up the scan area and interrogate the stress display. Stress data is produced by detecting minute temperature changes, down to one-thousandth of a degree Centigrade, resulting from the application to the structure of dynamic loading. The electronic data processing system correlates the temperature changes with a reference signal to determine stress level.

Dual wavelength imaging allows analysis of membrane fusion of influenza virus inside cells.

PubMed

Sakai, Tatsuya; Ohuchi, Masanobu; Imai, Masaki; Mizuno, Takafumi; Kawasaki, Kazunori; Kuroda, Kazumichi; Yamashina, Shohei

2006-02-01

Influenza virus hemagglutinin (HA) is a determinant of virus infectivity. Therefore, it is important to determine whether HA of a new influenza virus, which can potentially cause pandemics, is functional against human cells. The novel imaging technique reported here allows rapid analysis of HA function by visualizing viral fusion inside cells. This imaging was designed to detect fusion changing the spectrum of the fluorescence-labeled virus. Using this imaging, we detected the fusion between a virus and a very small endosome that could not be detected previously, indicating that the imaging allows highly sensitive detection of viral fusion.

Luminescent Tension-Indicating Orthopedic Strain Gauges for Non-Invasive Measurements Through Tissue

NASA Technical Reports Server (NTRS)

Anker, Jeffrey (Inventor); Anderson, Dakota (Inventor); Heath, Jonathon (Inventor); Rogalski, Melissa (Inventor)

2015-01-01

Strain gauges that can provide information with regard to the state of implantable devices are described. The strain gauges can exhibit luminescence that is detectable through living tissue, and the detectable luminescent emission can vary according to the strain applied to the gauge. A change in residual strain of the device can signify a loss of mechanical integrity and/or loosening of the implant, and this can be non-invasively detected either by simple visual detection of the luminescent emission or through examination of the emission with a detector such as a spectrometer or a camera.

Influence of visual clutter on the effect of navigated safety inspection: a case study on elevator installation.

PubMed

Liao, Pin-Chao; Sun, Xinlu; Liu, Mei; Shih, Yu-Nien

2018-01-11

Navigated safety inspection based on task-specific checklists can increase the hazard detection rate, theoretically with interference from scene complexity. Visual clutter, a proxy of scene complexity, can theoretically impair visual search performance, but its impact on the effect of safety inspection performance remains to be explored for the optimization of navigated inspection. This research aims to explore whether the relationship between working memory and hazard detection rate is moderated by visual clutter. Based on a perceptive model of hazard detection, we: (a) developed a mathematical influence model for construction hazard detection; (b) designed an experiment to observe the performance of hazard detection rate with adjusted working memory under different levels of visual clutter, while using an eye-tracking device to observe participants' visual search processes; (c) utilized logistic regression to analyze the developed model under various visual clutter. The effect of a strengthened working memory on the detection rate through increased search efficiency is more apparent in high visual clutter. This study confirms the role of visual clutter in construction-navigated inspections, thus serving as a foundation for the optimization of inspection planning.

Parallel detection of violations of color constancy

PubMed Central

Foster, David H.; Nascimento, Sérgio M. C.; Amano, Kinjiro; Arend, Larry; Linnell, Karina J.; Nieves, Juan Luis; Plet, Sabrina; Foster, Jeffrey S.

2001-01-01

The perceived colors of reflecting surfaces generally remain stable despite changes in the spectrum of the illuminating light. This color constancy can be measured operationally by asking observers to distinguish illuminant changes on a scene from changes in the reflecting properties of the surfaces comprising it. It is shown here that during fast illuminant changes, simultaneous changes in spectral reflectance of one or more surfaces in an array of other surfaces can be readily detected almost independent of the numbers of surfaces, suggesting a preattentive, spatially parallel process. This process, which is perfect over a spatial window delimited by the anatomical fovea, may form an early input to a multistage analysis of surface color, providing the visual system with information about a rapidly changing world in advance of the generation of a more elaborate and stable perceptual representation. PMID:11438751

Development of a widefield reflectance and fluorescence imaging device for the detection of skin and oral cancer

NASA Astrophysics Data System (ADS)

Pratavieira, S.; Santos, P. L. A.; Bagnato, V. S.; Kurachi, C.

2009-06-01

Oral and skin cancers constitute a major global health problem that cause great impact in patients. The most common screening method for oral cancer is visual inspection and palpation of the mouth. Visual examination relies heavily on the experience and skills of the physician to identify and delineate early premalignant and cancer changes, which is not simple due to the similar characteristics of early stage cancers and benign lesions. Optical imaging has the potential to address these clinical challenges. Contrast between normal and neoplastic areas may be increased, distinct to the conventional white light, when using illumination and detection conditions. Reflectance imaging can detect local changes in tissue scattering and absorption and fluorescence imaging can probe changes in the biochemical composition. These changes have shown to be indicatives of malignant progression. Widefield optical imaging systems are interesting because they may enhance the screening ability in large regions allowing the discrimination and the delineation of neoplastic and potentially of occult lesions. Digital image processing allows the combination of autofluorescence and reflectance images in order to objectively identify and delineate the peripheral extent of neoplastic lesions in the skin and oral cavity. Combining information from different imaging modalities has the potential of increasing diagnostic performance, due to distinct provided information. A simple widefiled imaging device based on fluorescence and reflectance modes together with a digital image processing was assembled and its performance tested in an animal study.

Seeing the Errors You Feel Enhances Locomotor Performance but Not Learning.

PubMed

Roemmich, Ryan T; Long, Andrew W; Bastian, Amy J

2016-10-24

In human motor learning, it is thought that the more information we have about our errors, the faster we learn. Here, we show that additional error information can lead to improved motor performance without any concomitant improvement in learning. We studied split-belt treadmill walking that drives people to learn a new gait pattern using sensory prediction errors detected by proprioceptive feedback. When we also provided visual error feedback, participants acquired the new walking pattern far more rapidly and showed accelerated restoration of the normal walking pattern during washout. However, when the visual error feedback was removed during either learning or washout, errors reappeared with performance immediately returning to the level expected based on proprioceptive learning alone. These findings support a model with two mechanisms: a dual-rate adaptation process that learns invariantly from sensory prediction error detected by proprioception and a visual-feedback-dependent process that monitors learning and corrects residual errors but shows no learning itself. We show that our voluntary correction model accurately predicted behavior in multiple situations where visual feedback was used to change acquisition of new walking patterns while the underlying learning was unaffected. The computational and behavioral framework proposed here suggests that parallel learning and error correction systems allow us to rapidly satisfy task demands without necessarily committing to learning, as the relative permanence of learning may be inappropriate or inefficient when facing environments that are liable to change. Copyright © 2016 Elsevier Ltd. All rights reserved.

Visual inspection of cervix with acetic acid: a good alternative to pap smear for cervical cancer screening in resource-limited setting.

PubMed

Khan, Momna; Sultana, Syeda Seema; Jabeen, Nigar; Arain, Uzma; Khans, Salma

2015-02-01

To determine the diagnostic accuracy of visual inspection of cervix using 3% acetic acid as a screening test for early detection of cervical cancer taking histopathology as the gold standard. The cross-sectional study was conducted at Civil Hospital Karachi from July 1 to December 31, 2012 and comprised all sexually active women aged 19-60 years. During speculum examination 3% acetic acid was applied over the cervix with the help of cotton swab. The observations were noted as positive or negative on visual inspection of the cervix after acetic acid application according to acetowhite changes. Colposcopy-guided cervical biopsy was done in patients with positive or abnormal looking cervix. Colposcopic-directed biopsy was taken as the gold standard to assess visual inspection readings. SPSS 17 was used for statistical analysis. There were 500 subjects with a mean age of 35.74 ± 9.64 years. Sensitivity, specifically, positive predicted value, negative predicted value of visual inspection of the cervix after acetic acid application was 93.5%, 95.8%, 76.3%, 99%, and the diagnostic accuracy was 95.6%. Visual inspection of the cervix after acetic acid application is an effective method of detecting pre-invasive phase of cervical cancer and a good alternative to cytological screening for cervical cancer in resource-poor setting like Pakistan and can reduce maternal morbidity and mortality.

Left Gastric Vein Visualization with Hepatopetal Flow Information in Healthy Subjects Using Non-Contrast-Enhanced Magnetic Resonance Angiography with Balanced Steady-State Free-Precession Sequence and Time-Spatial Labeling Inversion Pulse.

PubMed

Furuta, Akihiro; Isoda, Hiroyoshi; Ohno, Tsuyoshi; Ono, Ayako; Yamashita, Rikiya; Arizono, Shigeki; Kido, Aki; Sakashita, Naotaka; Togashi, Kaori

2018-01-01

To selectively visualize the left gastric vein (LGV) with hepatopetal flow information by non-contrast-enhanced magnetic resonance angiography under a hypothesis that change in the LGV flow direction can predict the development of esophageal varices; and to optimize the acquisition protocol in healthy subjects. Respiratory-gated three-dimensional balanced steady-state free-precession scans were conducted on 31 healthy subjects using two methods (A and B) for visualizing the LGV with hepatopetal flow. In method A, two time-spatial labeling inversion pulses (Time-SLIP) were placed on the whole abdomen and the area from the gastric fornix to the upper body, excluding the LGV area. In method B, nonselective inversion recovery pulse was used and one Time-SLIP was placed on the esophagogastric junction. The detectability and consistency of LGV were evaluated using the two methods and ultrasonography (US). Left gastric veins by method A, B, and US were detected in 30 (97%), 24 (77%), and 23 (74%) subjects, respectively. LGV flow by US was hepatopetal in 22 subjects and stagnant in one subject. All hepatopetal LGVs by US coincided with the visualized vessels in both methods. One subject with non-visualized LGV in method A showed stagnant LGV by US. Hepatopetal LGV could be selectively visualized by method A in healthy subjects.

Perceptual Learning Selectively Refines Orientation Representations in Early Visual Cortex

PubMed Central

Jehee, Janneke F.M.; Ling, Sam; Swisher, Jascha D.; van Bergen, Ruben S.; Tong, Frank

2013-01-01

Although practice has long been known to improve perceptual performance, the neural basis of this improvement in humans remains unclear. Using fMRI in conjunction with a novel signal detection-based analysis, we show that extensive practice selectively enhances the neural representation of trained orientations in the human visual cortex. Twelve observers practiced discriminating small changes in the orientation of a laterally presented grating over 20 or more daily one-hour training sessions. Training on average led to a two-fold improvement in discrimination sensitivity, specific to the trained orientation and the trained location, with minimal improvement found for untrained orthogonal orientations or for orientations presented in the untrained hemifield. We measured the strength of orientation-selective responses in individual voxels in early visual areas (V1–V4) using signal detection measures, both pre- and post-training. Although the overall amplitude of the BOLD response was no greater after training, practice nonetheless specifically enhanced the neural representation of the trained orientation at the trained location. This training-specific enhancement of orientation-selective responses was observed in the primary visual cortex (V1) as well as higher extrastriate visual areas V2–V4, and moreover, reliably predicted individual differences in the behavioral effects of perceptual learning. These results demonstrate that extensive training can lead to targeted functional reorganization of the human visual cortex, refining the cortical representation of behaviorally relevant information. PMID:23175828

Perceptual learning selectively refines orientation representations in early visual cortex.

PubMed

Jehee, Janneke F M; Ling, Sam; Swisher, Jascha D; van Bergen, Ruben S; Tong, Frank

2012-11-21

Although practice has long been known to improve perceptual performance, the neural basis of this improvement in humans remains unclear. Using fMRI in conjunction with a novel signal detection-based analysis, we show that extensive practice selectively enhances the neural representation of trained orientations in the human visual cortex. Twelve observers practiced discriminating small changes in the orientation of a laterally presented grating over 20 or more daily 1 h training sessions. Training on average led to a twofold improvement in discrimination sensitivity, specific to the trained orientation and the trained location, with minimal improvement found for untrained orthogonal orientations or for orientations presented in the untrained hemifield. We measured the strength of orientation-selective responses in individual voxels in early visual areas (V1-V4) using signal detection measures, both before and after training. Although the overall amplitude of the BOLD response was no greater after training, practice nonetheless specifically enhanced the neural representation of the trained orientation at the trained location. This training-specific enhancement of orientation-selective responses was observed in the primary visual cortex (V1) as well as higher extrastriate visual areas V2-V4, and moreover, reliably predicted individual differences in the behavioral effects of perceptual learning. These results demonstrate that extensive training can lead to targeted functional reorganization of the human visual cortex, refining the cortical representation of behaviorally relevant information.

Synchronous activity in cat visual cortex encodes collinear and cocircular contours.

PubMed

Samonds, Jason M; Zhou, Zhiyi; Bernard, Melanie R; Bonds, A B

2006-04-01

We explored how contour information in primary visual cortex might be embedded in the simultaneous activity of multiple cells recorded with a 100-electrode array. Synchronous activity in cat visual cortex was more selective and predictable in discriminating between drifting grating and concentric ring stimuli than changes in firing rate. Synchrony was found even between cells with wholly different orientation preferences when their receptive fields were circularly aligned, and membership in synchronous groups was orientation and curvature dependent. The existence of synchrony between cocircular cells reinforces its role as a general mechanism for contour integration and shape detection as predicted by association field concepts. Our data suggest that cortical synchrony results from common and synchronous input from earlier visual areas and that it could serve to shape extrastriate response selectivity.

Graded Neuronal Modulations Related to Visual Spatial Attention.

PubMed

Mayo, J Patrick; Maunsell, John H R

2016-05-11

Studies of visual attention in monkeys typically measure neuronal activity when the stimulus event to be detected occurs at a cued location versus when it occurs at an uncued location. But this approach does not address how neuronal activity changes relative to conditions where attention is unconstrained by cueing. Human psychophysical studies have used neutral cueing conditions and found that neutrally cued behavioral performance is generally intermediate to that of cued and uncued conditions (Posner et al., 1978; Mangun and Hillyard, 1990; Montagna et al., 2009). To determine whether the neuronal correlates of visual attention during neutral cueing are similarly intermediate, we trained macaque monkeys to detect changes in stimulus orientation that were more likely to occur at one location (cued) than another (uncued), or were equally likely to occur at either stimulus location (neutral). Consistent with human studies, performance was best when the location was cued, intermediate when both locations were neutrally cued, and worst when the location was uncued. Neuronal modulations in visual area V4 were also graded as a function of cue validity and behavioral performance. By recording from both hemispheres simultaneously, we investigated the possibility of switching attention between stimulus locations during neutral cueing. The results failed to support a unitary "spotlight" of attention. Overall, our findings indicate that attention-related changes in V4 are graded to accommodate task demands. Studies of the neuronal correlates of attention in monkeys typically use visual cues to manipulate where attention is focused ("cued" vs "uncued"). Human psychophysical studies often also include neutrally cued trials to study how attention naturally varies between points of interest. But the neuronal correlates of this neutral condition are unclear. We measured behavioral performance and neuronal activity in cued, uncued, and neutrally cued blocks of trials. Behavioral performance and neuronal responses during neutral cueing were intermediate to those of the cued and uncued conditions. We found no signatures of a single mechanism of attention that switches between stimulus locations. Thus, attention-related changes in neuronal activity are largely hemisphere-specific and graded according to task demands. Copyright © 2016 the authors 0270-6474/16/365353-09$15.00/0.

Graded Neuronal Modulations Related to Visual Spatial Attention

PubMed Central

Maunsell, John H. R.

2016-01-01

Studies of visual attention in monkeys typically measure neuronal activity when the stimulus event to be detected occurs at a cued location versus when it occurs at an uncued location. But this approach does not address how neuronal activity changes relative to conditions where attention is unconstrained by cueing. Human psychophysical studies have used neutral cueing conditions and found that neutrally cued behavioral performance is generally intermediate to that of cued and uncued conditions (Posner et al., 1978; Mangun and Hillyard, 1990; Montagna et al., 2009). To determine whether the neuronal correlates of visual attention during neutral cueing are similarly intermediate, we trained macaque monkeys to detect changes in stimulus orientation that were more likely to occur at one location (cued) than another (uncued), or were equally likely to occur at either stimulus location (neutral). Consistent with human studies, performance was best when the location was cued, intermediate when both locations were neutrally cued, and worst when the location was uncued. Neuronal modulations in visual area V4 were also graded as a function of cue validity and behavioral performance. By recording from both hemispheres simultaneously, we investigated the possibility of switching attention between stimulus locations during neutral cueing. The results failed to support a unitary “spotlight” of attention. Overall, our findings indicate that attention-related changes in V4 are graded to accommodate task demands. SIGNIFICANCE STATEMENT Studies of the neuronal correlates of attention in monkeys typically use visual cues to manipulate where attention is focused (“cued” vs “uncued”). Human psychophysical studies often also include neutrally cued trials to study how attention naturally varies between points of interest. But the neuronal correlates of this neutral condition are unclear. We measured behavioral performance and neuronal activity in cued, uncued, and neutrally cued blocks of trials. Behavioral performance and neuronal responses during neutral cueing were intermediate to those of the cued and uncued conditions. We found no signatures of a single mechanism of attention that switches between stimulus locations. Thus, attention-related changes in neuronal activity are largely hemisphere-specific and graded according to task demands. PMID:27170131

Clinical Outcomes of an Optimized Prolate Ablation Procedure for Correcting Residual Refractive Errors Following Laser Surgery.

PubMed

Chung, Byunghoon; Lee, Hun; Choi, Bong Joon; Seo, Kyung Ryul; Kim, Eung Kwon; Kim, Dae Yune; Kim, Tae-Im

2017-02-01

The purpose of this study was to investigate the clinical efficacy of an optimized prolate ablation procedure for correcting residual refractive errors following laser surgery. We analyzed 24 eyes of 15 patients who underwent an optimized prolate ablation procedure for the correction of residual refractive errors following laser in situ keratomileusis, laser-assisted subepithelial keratectomy, or photorefractive keratectomy surgeries. Preoperative ophthalmic examinations were performed, and uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction values (sphere, cylinder, and spherical equivalent), point spread function, modulation transfer function, corneal asphericity (Q value), ocular aberrations, and corneal haze measurements were obtained postoperatively at 1, 3, and 6 months. Uncorrected distance visual acuity improved and refractive errors decreased significantly at 1, 3, and 6 months postoperatively. Total coma aberration increased at 3 and 6 months postoperatively, while changes in all other aberrations were not statistically significant. Similarly, no significant changes in point spread function were detected, but modulation transfer function increased significantly at the postoperative time points measured. The optimized prolate ablation procedure was effective in terms of improving visual acuity and objective visual performance for the correction of persistent refractive errors following laser surgery.

Beauty hinders attention switch in change detection: the role of facial attractiveness and distinctiveness.

PubMed

Chen, Wenfeng; Liu, Chang Hong; Nakabayashi, Kazuyo

2012-01-01

Recent research has shown that the presence of a task-irrelevant attractive face can induce a transient diversion of attention from a perceptual task that requires covert deployment of attention to one of the two locations. However, it is not known whether this spontaneous appraisal for facial beauty also modulates attention in change detection among multiple locations, where a slower, and more controlled search process is simultaneously affected by the magnitude of a change and the facial distinctiveness. Using the flicker paradigm, this study examines how spontaneous appraisal for facial beauty affects the detection of identity change among multiple faces. Participants viewed a display consisting of two alternating frames of four faces separated by a blank frame. In half of the trials, one of the faces (target face) changed to a different person. The task of the participant was to indicate whether a change of face identity had occurred. The results showed that (1) observers were less efficient at detecting identity change among multiple attractive faces relative to unattractive faces when the target and distractor faces were not highly distinctive from one another; and (2) it is difficult to detect a change if the new face is similar to the old. The findings suggest that attractive faces may interfere with the attention-switch process in change detection. The results also show that attention in change detection was strongly modulated by physical similarity between the alternating faces. Although facial beauty is a powerful stimulus that has well-demonstrated priority, its influence on change detection is easily superseded by low-level image similarity. The visual system appears to take a different approach to facial beauty when a task requires resource-demanding feature comparisons.

Loop-Mediated Isothermal Amplification for Detection of Endogenous Sad1 Gene in Cotton: An Internal Control for Rapid Onsite GMO Testing.

PubMed

Singh, Monika; Bhoge, Rajesh K; Randhawa, Gurinderjit

2018-04-20

Background : Confirming the integrity of seed samples in powdered form is important priorto conducting a genetically modified organism (GMO) test. Rapid onsite methods may provide a technological solution to check for genetically modified (GM) events at ports of entry. In India, Bt cotton is the commercialized GM crop with four approved GM events; however, 59 GM events have been approved globally. GMO screening is required to test for authorized GM events. The identity and amplifiability of test samples could be ensured first by employing endogenous genes as an internal control. Objective : A rapid onsite detection method was developed for an endogenous reference gene, stearoyl acyl carrier protein desaturase ( Sad1 ) of cotton, employing visual and real-time loop-mediated isothermal amplification (LAMP). Methods : The assays were performed at a constant temperature of 63°C for 30 min for visual LAMP and 62ºC for 40 min for real-time LAMP. Positive amplification was visualized as a change in color from orange to green on addition of SYBR ® Green or detected as real-time amplification curves. Results : Specificity of LAMP assays was confirmed using a set of 10 samples. LOD for visual LAMP was up to 0.1%, detecting 40 target copies, and for real-time LAMP up to 0.05%, detecting 20 target copies. Conclusions : The developed methods could be utilized to confirm the integrity of seed powder prior to conducting a GMO test for specific GM events of cotton. Highlights : LAMP assays for the endogenous Sad1 gene of cotton have been developed to be used as an internal control for onsite GMO testing in cotton.

Detection of longitudinal visual field progression in glaucoma using machine learning.

PubMed

Yousefi, Siamak; Kiwaki, Taichi; Zheng, Yuhui; Suigara, Hiroki; Asaoka, Ryo; Murata, Hiroshi; Lemij, Hans; Yamanishi, Kenji

2018-06-16

Global indices of standard automated perimerty are insensitive to localized losses, while point-wise indices are sensitive but highly variable. Region-wise indices sit in between. This study introduces a machine-learning-based index for glaucoma progression detection that outperforms global, region-wise, and point-wise indices. Development and comparison of a prognostic index. Visual fields from 2085 eyes of 1214 subjects were used to identify glaucoma progression patterns using machine learning. Visual fields from 133 eyes of 71 glaucoma patients were collected 10 times over 10 weeks to provide a no-change, test-retest dataset. The parameters of all methods were identified using visual field sequences in the test-retest dataset to meet fixed 95% specificity. An independent dataset of 270 eyes of 136 glaucoma patients and survival analysis were utilized to compare methods. The time to detect progression in 25% of the eyes in the longitudinal dataset using global mean deviation (MD) was 5.2 years (95% confidence interval, 4.1 - 6.5 years); 4.5 years (4.0 - 5.5) using region-wise, 3.9 years (3.5 - 4.6) using point-wise, and 3.5 years (3.1 - 4.0) using machine learning analysis. The time until 25% of eyes showed subsequently confirmed progression after two additional visits were included were 6.6 years (5.6 - 7.4 years), 5.7 years (4.8 - 6.7), 5.6 years (4.7 - 6.5), and 5.1 years (4.5 - 6.0) for global, region-wise, point-wise, and machine learning analyses, respectively. Machine learning analysis detects progressing eyes earlier than other methods consistently, with or without confirmation visits. In particular, machine learning detects more slowly progressing eyes than other methods. Copyright © 2018 Elsevier Inc. All rights reserved.

A visual model for object detection based on active contours and level-set method.

PubMed

Satoh, Shunji

2006-09-01

A visual model for object detection is proposed. In order to make the detection ability comparable with existing technical methods for object detection, an evolution equation of neurons in the model is derived from the computational principle of active contours. The hierarchical structure of the model emerges naturally from the evolution equation. One drawback involved with initial values of active contours is alleviated by introducing and formulating convexity, which is a visual property. Numerical experiments show that the proposed model detects objects with complex topologies and that it is tolerant of noise. A visual attention model is introduced into the proposed model. Other simulations show that the visual properties of the model are consistent with the results of psychological experiments that disclose the relation between figure-ground reversal and visual attention. We also demonstrate that the model tends to perceive smaller regions as figures, which is a characteristic observed in human visual perception.

Are multiple visual short-term memory storages necessary to explain the retro-cue effect?

PubMed

Makovski, Tal

2012-06-01

Recent research has shown that change detection performance is enhanced when, during the retention interval, attention is cued to the location of the upcoming test item. This retro-cue advantage has led some researchers to suggest that visual short-term memory (VSTM) is divided into a durable, limited-capacity storage and a more fragile, high-capacity storage. Consequently, performance is poor on the no-cue trials because fragile VSTM is overwritten by the test display and only durable VSTM is accessible under these conditions. In contrast, performance is improved in the retro-cue condition because attention keeps fragile VSTM accessible. The aim of the present study was to test the assumptions underlying this two-storage account. Participants were asked to encode an array of colors for a change detection task involving no-cue and retro-cue trials. A retro-cue advantage was found even when the cue was presented after a visual (Experiment 1) or a central (Experiment 2) interference. Furthermore, the magnitude of the interference was comparable between the no-cue and retro-cue trials. These data undermine the main empirical support for the two-storage account and suggest that the presence of a retro-cue benefit cannot be used to differentiate between different VSTM storages.

Phototaxis and the origin of visual eyes

PubMed Central

Randel, Nadine

2016-01-01

Vision allows animals to detect spatial differences in environmental light levels. High-resolution image-forming eyes evolved from low-resolution eyes via increases in photoreceptor cell number, improvements in optics and changes in the neural circuits that process spatially resolved photoreceptor input. However, the evolutionary origins of the first low-resolution visual systems have been unclear. We propose that the lowest resolving (two-pixel) visual systems could initially have functioned in visual phototaxis. During visual phototaxis, such elementary visual systems compare light on either side of the body to regulate phototactic turns. Another, even simpler and non-visual strategy is characteristic of helical phototaxis, mediated by sensory–motor eyespots. The recent mapping of the complete neural circuitry (connectome) of an elementary visual system in the larva of the annelid Platynereis dumerilii sheds new light on the possible paths from non-visual to visual phototaxis and to image-forming vision. We outline an evolutionary scenario focusing on the neuronal circuitry to account for these transitions. We also present a comprehensive review of the structure of phototactic eyes in invertebrate larvae and assign them to the non-visual and visual categories. We propose that non-visual systems may have preceded visual phototactic systems in evolution that in turn may have repeatedly served as intermediates during the evolution of image-forming eyes. PMID:26598725

Quality labeled faces in the wild (QLFW): a database for studying face recognition in real-world environments

NASA Astrophysics Data System (ADS)

Karam, Lina J.; Zhu, Tong

2015-03-01

The varying quality of face images is an important challenge that limits the effectiveness of face recognition technology when applied in real-world applications. Existing face image databases do not consider the effect of distortions that commonly occur in real-world environments. This database (QLFW) represents an initial attempt to provide a set of labeled face images spanning the wide range of quality, from no perceived impairment to strong perceived impairment for face detection and face recognition applications. Types of impairment include JPEG2000 compression, JPEG compression, additive white noise, Gaussian blur and contrast change. Subjective experiments are conducted to assess the perceived visual quality of faces under different levels and types of distortions and also to assess the human recognition performance under the considered distortions. One goal of this work is to enable automated performance evaluation of face recognition technologies in the presence of different types and levels of visual distortions. This will consequently enable the development of face recognition systems that can operate reliably on real-world visual content in the presence of real-world visual distortions. Another goal is to enable the development and assessment of visual quality metrics for face images and for face detection and recognition applications.

Passive acoustic monitoring of coastally associated Hawaiian spinner dolphins, Stenella longirostris, ground-truthed through visual surveys.

PubMed

Heenehan, Heather L; Tyne, Julian A; Bejder, Lars; Van Parijs, Sofie M; Johnston, David W

2016-07-01

Effective decision making to protect coastally associated dolphins relies on monitoring the presence of animals in areas that are critical to their survival. Hawaiian spinner dolphins forage at night and rest during the day in shallow bays. Due to their predictable presence, they are targeted by dolphin-tourism. In this study, comparisons of presence were made between passive acoustic monitoring (PAM) and vessel-based visual surveys in Hawaiian spinner dolphin resting bays. DSG-Ocean passive acoustic recording devices were deployed in four bays along the Kona Coast of Hawai'i Island between January 8, 2011 and August 30, 2012. The devices sampled at 80 kHz, making 30-s recordings every four minutes. Overall, dolphins were acoustically detected on 37.1% to 89.6% of recording days depending on the bay. Vessel-based visual surveys overlapped with the PAM surveys on 202 days across the four bays. No significant differences were found between visual and acoustic detections suggesting acoustic surveys can be used as a proxy for visual surveys. Given the need to monitor dolphin presence across sites, PAM is the most suitable and efficient tool for monitoring long-term presence/absence. Concomitant photo-identification surveys are necessary to address changes in abundance over time.

Icon Duration and Development.

ERIC Educational Resources Information Center

Gummerman, Kent; And Others

In this study, developmental changes in duration of the icon (visual sensory store) were investigated with three converging tachistoscopic tasks. (1) Stimulus interuption detection (SID), a variation of the two-flash threshold method, was performed by 29 first- and 32 fifth-graders, and 32 undergraduates. Icon duration was estimated by stimulus…

A comparison of the vigilance performance of men and women using a simulated radar task.

DOT National Transportation Integrated Search

1978-03-01

The present study examined the question of possible sex differences in the ability to sustain attention to a complex monitoring task requiring only a detection response to critical stimulus changes. The visual display was designed to approximate a fu...

40 CFR 63.9631 - What are my monitoring requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... maintain a bag leak detection system to monitor the relative change in particulate matter loadings... of ensuring the proper functioning of removal mechanisms. (3) Check the compressed air supply of... interior for air leaks. (8) Inspect fans for wear, material buildup, and corrosion through quarterly visual...

“Global” visual training and extent of transfer in amblyopic macaque monkeys

PubMed Central

Kiorpes, Lynne; Mangal, Paul

2015-01-01

Perceptual learning is gaining acceptance as a potential treatment for amblyopia in adults and children beyond the critical period. Many perceptual learning paradigms result in very specific improvement that does not generalize beyond the training stimulus, closely related stimuli, or visual field location. To be of use in amblyopia, a less specific effect is needed. To address this problem, we designed a more general training paradigm intended to effect improvement in visual sensitivity across tasks and domains. We used a “global” visual stimulus, random dot motion direction discrimination with 6 training conditions, and tested for posttraining improvement on a motion detection task and 3 spatial domain tasks (contrast sensitivity, Vernier acuity, Glass pattern detection). Four amblyopic macaques practiced the motion discrimination with their amblyopic eye for at least 20,000 trials. All showed improvement, defined as a change of at least a factor of 2, on the trained task. In addition, all animals showed improvements in sensitivity on at least some of the transfer test conditions, mainly the motion detection task; transfer to the spatial domain was inconsistent but best at fine spatial scales. However, the improvement on the transfer tasks was largely not retained at long-term follow-up. Our generalized training approach is promising for amblyopia treatment, but sustaining improved performance may require additional intervention. PMID:26505868

Gestalt Effects in Visual Working Memory.

PubMed

Kałamała, Patrycja; Sadowska, Aleksandra; Ordziniak, Wawrzyniec; Chuderski, Adam

2017-01-01

Four experiments investigated whether conforming to Gestalt principles, well known to drive visual perception, also facilitates the active maintenance of information in visual working memory (VWM). We used the change detection task, which required the memorization of visual patterns composed of several shapes. We observed no effects of symmetry of visual patterns on VWM performance. However, there was a moderate positive effect when a particular shape that was probed matched the shape of the whole pattern (the whole-part similarity effect). Data support the models assuming that VWM encodes not only particular objects of the perceptual scene but also the spatial relations between them (the ensemble representation). The ensemble representation may prime objects similar to its shape and thereby boost access to them. In contrast, the null effect of symmetry relates the fact that this very feature of an ensemble does not yield any useful additional information for VWM.

Attention distributed across sensory modalities enhances perceptual performance

PubMed Central

Mishra, Jyoti; Gazzaley, Adam

2012-01-01

This study investigated the interaction between top-down attentional control and multisensory processing in humans. Using semantically congruent and incongruent audiovisual stimulus streams, we found target detection to be consistently improved in the setting of distributed audiovisual attention versus focused visual attention. This performance benefit was manifested as faster reaction times for congruent audiovisual stimuli, and as accuracy improvements for incongruent stimuli, resulting in a resolution of stimulus interference. Electrophysiological recordings revealed that these behavioral enhancements were associated with reduced neural processing of both auditory and visual components of the audiovisual stimuli under distributed vs. focused visual attention. These neural changes were observed at early processing latencies, within 100–300 ms post-stimulus onset, and localized to auditory, visual, and polysensory temporal cortices. These results highlight a novel neural mechanism for top-down driven performance benefits via enhanced efficacy of sensory neural processing during distributed audiovisual attention relative to focused visual attention. PMID:22933811

Relationship between Structural and Functional Assessment of the Visual System in Mildly Disabled Relapsing-Remitting Multiple Sclerosis Patients

PubMed Central

Huseyinoglu, Nergiz; Ekinci, Metin; Ozben, Serkan; Buyukuysal, Cagatay

2014-01-01

Abstract Studies that explored the anterior visual pathway in the patients with multiple sclerosis (MS) have demonstrated contradictory results about the correlation between structural and functional status of optic nerve and retina. We aimed to investigate the functional and structural findings in our cohort of mildly disabled relapsing-remitting MS patients. A total of 134 eyes (80 eyes of the patients with MS and 54 eyes of the control group) were investigated. Eyes of MS patients were divided into two groups—as eyes with history of optic neuritis (ON group) and without history of optic neuritis (NON group). Ophthalmological investigation including visual evoked potentials, standard automated perimetry, and optical coherence tomography were performed for all participants. Retinal and macular thicknesses were significantly decreased in ON and NON groups compared with controls. Also, visual evoked potential latencies and visual field loss were worse in the both MS groups compared with control group. We did not find any correlation between visual evoked potentials and retinal or macular thickness values but visual field parameters were correlated between retinal and macular layer loss in the NON group. According to our results and some previous studies, although both functional and structural changes were detected in patients with MS, functional status markers do not always show parallelism (or synchrony) with structural changes, especially in eyes with history of optic neuritis. PMID:27928266

Multiple-object permanence tracking: limitation in maintenance and transformation of perceptual objects.

PubMed

Saiki, Jun

2002-01-01

Research on change blindness and transsaccadic memory revealed that a limited amount of information is retained across visual disruptions in visual working memory. It has been proposed that visual working memory can hold four to five coherent object representations. To investigate their maintenance and transformation in dynamic situations, I devised an experimental paradigm called multiple-object permanence tracking (MOPT) that measures memory for multiple feature-location bindings in dynamic situations. Observers were asked to detect any color switch in the middle of a regular rotation of a pattern with multiple colored disks behind an occluder. The color-switch detection performance dramatically declined as the pattern rotation velocity increased, and this effect of object motion was independent of the number of targets. The MOPT task with various shapes and colors showed that color-shape conjunctions are not available in the MOPT task. These results suggest that even completely predictable motion severely reduces our capacity of object representations, from four to only one or two.

Experimental and Computational Studies of Cortical Neural Network Properties Through Signal Processing

NASA Astrophysics Data System (ADS)

Clawson, Wesley Patrick

Previous studies, both theoretical and experimental, of network level dynamics in the cerebral cortex show evidence for a statistical phenomenon called criticality; a phenomenon originally studied in the context of phase transitions in physical systems and that is associated with favorable information processing in the context of the brain. The focus of this thesis is to expand upon past results with new experimentation and modeling to show a relationship between criticality and the ability to detect and discriminate sensory input. A line of theoretical work predicts maximal sensory discrimination as a functional benefit of criticality, which can then be characterized using mutual information between sensory input, visual stimulus, and neural response,. The primary finding of our experiments in the visual cortex in turtles and neuronal network modeling confirms this theoretical prediction. We show that sensory discrimination is maximized when visual cortex operates near criticality. In addition to presenting this primary finding in detail, this thesis will also address our preliminary results on change-point-detection in experimentally measured cortical dynamics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachman, D., E-mail: bachman@ualberta.ca; Fedosejevs, R.; Tsui, Y. Y.

An optical damage threshold for crystalline silicon from single femtosecond laser pulses was determined by detecting a permanent change in the refractive index of the material. This index change could be detected with unprecedented sensitivity by measuring the resonant wavelength shift of silicon integrated optics microring resonators irradiated with femtosecond laser pulses at 400 nm and 800 nm wavelengths. The threshold for permanent index change at 400 nm wavelength was determined to be 0.053 ± 0.007 J/cm{sup 2}, which agrees with previously reported threshold values for femtosecond laser modification of crystalline silicon. However, the threshold for index change at 800 nm wavelength was found to be 0.044 ± 0.005 J/cm{supmore » 2}, which is five times lower than the previously reported threshold values for visual change on the silicon surface. The discrepancy is attributed to possible modification of the crystallinity of silicon below the melting temperature that has not been detected before.« less

Dual-color plasmonic enzyme-linked immunosorbent assay based on enzyme-mediated etching of Au nanoparticles

NASA Astrophysics Data System (ADS)

Guo, Longhua; Xu, Shaohua; Ma, Xiaoming; Qiu, Bin; Lin, Zhenyu; Chen, Guonan

2016-09-01

Colorimetric enzyme-linked immunosorbent assay utilizing 3‧-3-5‧-5-tetramethylbenzidine(TMB) as the chromogenic substrate has been widely used in the hospital for the detection of all kinds of disease biomarkers. Herein, we demonstrate a strategy to change this single-color display into dual-color responses to improve the accuracy of visual inspection. Our investigation firstly reveals that oxidation state of 3‧-3-5‧-5-tetramethylbenzidine (TMB2+) can quantitatively etch gold nanoparticles. Therefore, the incorporation of gold nanoparticles into a commercial TMB-based ELISA kit could generate dual-color responses: the solution color varied gradually from wine red (absorption peak located at ~530 nm) to colorless, and then from colorless to yellow (absorption peak located at ~450 nm) with the increase amount of targets. These dual-color responses effectively improved the sensitivity as well as the accuracy of visual inspection. For example, the proposed dual-color plasmonic ELISA is demonstrated for the detection of prostate-specific antigen (PSA) in human serum with a visual limit of detection (LOD) as low as 0.0093 ng/mL.

Label-free visualization of collagen in submucosa as a potential diagnostic marker for early detection of colorectal cancer

NASA Astrophysics Data System (ADS)

Qiu, Jingting; Yang, Yinghong; Jiang, Weizhong; Feng, Changyin; Chen, Zhifen; Guan, Guoxian; Zhu, Xiaoqin; Zhuo, Shuangmu; Chen, Jianxin

2014-09-01

The collagen signature in colorectal submucosa is changed due to remodeling of the extracellular matrix during the malignant process and plays an important role in noninvasive early detection of human colorectal cancer. In this work, multiphoton microscopy (MPM) was used to monitor the changes of collagen in normal colorectal submucosa (NCS) and cancerous colorectal submucosa (CCS). What's more, the collagen content was quantitatively measured. It was found that in CCS the morphology of collagen becomes much looser and the collagen content is significantly reduced compared to NCS. These results suggest that MPM has the ability to provide collagen signature as a potential diagnostic marker for early detection of colorectal cancer.

Visual rehabilitation: visual scanning, multisensory stimulation and vision restoration trainings

PubMed Central

Dundon, Neil M.; Bertini, Caterina; Làdavas, Elisabetta; Sabel, Bernhard A.; Gall, Carolin

2015-01-01

Neuropsychological training methods of visual rehabilitation for homonymous vision loss caused by postchiasmatic damage fall into two fundamental paradigms: “compensation” and “restoration”. Existing methods can be classified into three groups: Visual Scanning Training (VST), Audio-Visual Scanning Training (AViST) and Vision Restoration Training (VRT). VST and AViST aim at compensating vision loss by training eye scanning movements, whereas VRT aims at improving lost vision by activating residual visual functions by training light detection and discrimination of visual stimuli. This review discusses the rationale underlying these paradigms and summarizes the available evidence with respect to treatment efficacy. The issues raised in our review should help guide clinical care and stimulate new ideas for future research uncovering the underlying neural correlates of the different treatment paradigms. We propose that both local “within-system” interactions (i.e., relying on plasticity within peri-lesional spared tissue) and changes in more global “between-system” networks (i.e., recruiting alternative visual pathways) contribute to both vision restoration and compensatory rehabilitation, which ultimately have implications for the rehabilitation of cognitive functions. PMID:26283935

Paper-based Platform for Urinary Creatinine Detection.

PubMed

Sittiwong, Jarinya; Unob, Fuangfa

2016-01-01

A new paper platform was developed for the colorimetric detection of creatinine. The filter paper was coated with 3-propylsulfonic acid trimethoxysilane and used as the platform. Creatinine in a cationic form was extracted onto the paper via an ion-exchange mechanism and detected through the Jaffé reaction, resulting in a yellow-orange color complex. The color change on the paper could be observed visually, and the quantitative detection of creatinine was achieved through monitoring the color intensity change. The color intensity of creatinine complexes on the paper platform as a function of the creatinine concentration provided a linear range for creatinine detection in the range of 10 - 60 mg L(-1) and a detection limit of 4.2 mg L(-1). The accuracy of the proposed paper-based method was comparable to the conventional standard Jaffé method. This paper platform could be applied for simple and rapid detection of creatinine in human urine samples with a low consumption of reagent.

Good vibrations: tactile feedback in support of attention allocation and human-automation coordination in event-driven domains.

PubMed

Sklar, A E; Sarter, N B

1999-12-01

Observed breakdowns in human-machine communication can be explained, in part, by the nature of current automation feedback, which relies heavily on focal visual attention. Such feedback is not well suited for capturing attention in case of unexpected changes and events or for supporting the parallel processing of large amounts of data in complex domains. As suggested by multiple-resource theory, one possible solution to this problem is to distribute information across various sensory modalities. A simulator study was conducted to compare the effectiveness of visual, tactile, and redundant visual and tactile cues for indicating unexpected changes in the status of an automated cockpit system. Both tactile conditions resulted in higher detection rates for, and faster response times to, uncommanded mode transitions. Tactile feedback did not interfere with, nor was its effectiveness affected by, the performance of concurrent visual tasks. The observed improvement in task-sharing performance indicates that the introduction of tactile feedback is a promising avenue toward better supporting human-machine communication in event-driven, information-rich domains.

Automatic Detection of Optic Disc in Retinal Image by Using Keypoint Detection, Texture Analysis, and Visual Dictionary Techniques

PubMed Central

Bayır, Şafak

2016-01-01

With the advances in the computer field, methods and techniques in automatic image processing and analysis provide the opportunity to detect automatically the change and degeneration in retinal images. Localization of the optic disc is extremely important for determining the hard exudate lesions or neovascularization, which is the later phase of diabetic retinopathy, in computer aided eye disease diagnosis systems. Whereas optic disc detection is fairly an easy process in normal retinal images, detecting this region in the retinal image which is diabetic retinopathy disease may be difficult. Sometimes information related to optic disc and hard exudate information may be the same in terms of machine learning. We presented a novel approach for efficient and accurate localization of optic disc in retinal images having noise and other lesions. This approach is comprised of five main steps which are image processing, keypoint extraction, texture analysis, visual dictionary, and classifier techniques. We tested our proposed technique on 3 public datasets and obtained quantitative results. Experimental results show that an average optic disc detection accuracy of 94.38%, 95.00%, and 90.00% is achieved, respectively, on the following public datasets: DIARETDB1, DRIVE, and ROC. PMID:27110272

Visual detection of driving while intoxicated. Project interim report : identification of visual cues and development of detection methods

DOT National Transportation Integrated Search

1979-01-01

The report describes the initial phase of a two-phase project on the visual, on-the-road detection of driving while intoxicated (DWI). The purpose of the overall project is to develop and test procedures for enhancing on-the-road detection of DWI. Th...

Occipitoparietal alpha-band responses to the graded allocation of top-down spatial attention.

PubMed

Dombrowe, Isabel; Hilgetag, Claus C

2014-09-15

The voluntary, top-down allocation of visual spatial attention has been linked to changes in the alpha-band of the electroencephalogram (EEG) signal measured over occipital and parietal lobes. In the present study, we investigated how occipitoparietal alpha-band activity changes when people allocate their attentional resources in a graded fashion across the visual field. We asked participants to either completely shift their attention into one hemifield, to balance their attention equally across the entire visual field, or to attribute more attention to one-half of the visual field than to the other. As expected, we found that alpha-band amplitudes decreased stronger contralaterally than ipsilaterally to the attended side when attention was shifted completely. Alpha-band amplitudes decreased bilaterally when attention was balanced equally across the visual field. However, when participants allocated more attentional resources to one-half of the visual field, this was not reflected in the alpha-band amplitudes, which just decreased bilaterally. We found that the performance of the participants was more strongly reflected in the coherence between frontal and occipitoparietal brain regions. We conclude that low alpha-band amplitudes seem to be necessary for stimulus detection. Furthermore, complete shifts of attention are directly reflected in the lateralization of alpha-band amplitudes. In the present study, a gradual allocation of visual attention across the visual field was only indirectly reflected in the alpha-band activity over occipital and parietal cortexes. Copyright © 2014 the American Physiological Society.

The Feasibility Evaluation of Land Use Change Detection Using GAOFEN-3 Data

NASA Astrophysics Data System (ADS)

Huang, G.; Sun, Y.; Zhao, Z.

2018-04-01

GaoFen-3 (GF-3) satellite, is the first C band and multi-polarimetric Synthetic Aperture Radar (SAR) satellite in China. In order to explore the feasibility of GF-3 satellite in remote sensing interpretation and land-use remote sensing change detection, taking Guangzhou, China as a study area, the full polarimetric image of GF-3 satellite with 8 m resolution of two temporal as the data source. Firstly, the image is pre-processed by orthorectification, image registration and mosaic, and the land-use remote sensing digital orthophoto map (DOM) in 2017 is made according to the each county. Then the classification analysis and judgment of ground objects on the image are carried out by means of ArcGIS combining with the auxiliary data and using artificial visual interpretation, to determine the area of changes and the category of change objects. According to the unified change information extraction principle to extract change areas. Finally, the change detection results are compared with 3 m resolution TerraSAR-X data and 2 m resolution multi-spectral image, and the accuracy is evaluated. Experimental results show that the accuracy of the GF-3 data is over 75 % in detecting the change of ground objects, and the detection capability of new filling soil is better than that of TerraSAR-X data, verify the detection and monitoring capability of GF-3 data to the change information extraction, also, it shows that GF-3 can provide effective data support for the remote sensing detection of land resources.

Short-term saccadic adaptation in the macaque monkey: a binocular mechanism

PubMed Central

Schultz, K. P.

2013-01-01

Saccadic eye movements are rapid transfers of gaze between objects of interest. Their duration is too short for the visual system to be able to follow their progress in time. Adaptive mechanisms constantly recalibrate the saccadic responses by detecting how close the landings are to the selected targets. The double-step saccadic paradigm is a common method to simulate alterations in saccadic gain. While the subject is responding to a first target shift, a second shift is introduced in the middle of this movement, which masks it from visual detection. The error in landing introduced by the second shift is interpreted by the brain as an error in the programming of the initial response, with gradual gain changes aimed at compensating the apparent sensorimotor mismatch. A second shift applied dichoptically to only one eye introduces disconjugate landing errors between the two eyes. A monocular adaptive system would independently modify only the gain of the eye exposed to the second shift in order to reestablish binocular alignment. Our results support a binocular mechanism. A version-based saccadic adaptive process detects postsaccadic version errors and generates compensatory conjugate gain alterations. A vergence-based saccadic adaptive process detects postsaccadic disparity errors and generates corrective nonvisual disparity signals that are sent to the vergence system to regain binocularity. This results in striking dynamical similarities between visually driven combined saccade-vergence gaze transfers, where the disparity is given by the visual targets, and the double-step adaptive disconjugate responses, where an adaptive disparity signal is generated internally by the saccadic system. PMID:23076111

D Visualization of Mangrove and Aquaculture Conversion in Banate Bay, Iloilo

NASA Astrophysics Data System (ADS)

Domingo, G. A.; Mallillin, M. M.; Perez, A. M. C.; Claridades, A. R. C.; Tamondong, A. M.

2017-10-01

Studies have shown that mangrove forests in the Philippines have been drastically reduced due to conversion to fishponds, salt ponds, reclamation, as well as other forms of industrial development and as of 2011, Iloilo's 95 % mangrove forest was converted to fishponds. In this research, six (6) Landsat images acquired on the years 1973, 1976, 2000, 2006, 2010, and 2016, were classified using Support Vector Machine (SVM) Classification to determine land cover changes, particularly the area change of mangrove and aquaculture from 1976 to 2016. The results of the classification were used as layers for the generation of 3D visualization models using four (4) platforms namely Google Earth, ArcScene, Virtual Terrain Project, and Terragen. A perception survey was conducted among respondents with different levels of expertise in spatial analysis, 3D visualization, as well as in forestry, fisheries, and aquatic resources to assess the usability, effectiveness, and potential of the various platforms used. Change detection showed that largest negative change for mangrove areas happened from 1976 to 2000, with the mangrove area decreasing from 545.374 hectares to 286.935 hectares. Highest increase in fishpond area occurred from 1973 to 1976 rising from 2,930.67 hectares to 3,441.51 hectares. Results of the perception survey showed that ArcScene is preferred for spatial analysis while respondents favored Terragen for 3D visualization and for forestry, fishery and aquatic resources applications.

Real-Time Tissue Change Monitoring on the Sonablate® 500 during High Intensity Focused Ultrasound (HIFU) Treatment of Prostate Cancer

NASA Astrophysics Data System (ADS)

Chen, Wo-Hsing; Sanghvi, Narendra T.; Carlson, Roy; Uchida, Toyoaki

2011-09-01

Sonablate® 500 (SB-500) HIFU devices have been successfully used to treat prostate cancer non-invasively. In addition, Visually Directed HIFU with the SB-500 has demonstrated higher efficacy. Visually Directed HIFU works by displaying hyperechoic changes on the B-mode ultrasound images. However, small changes in the grey-scale images are not detectable by Visually Directed HIFU. To detect all tissue changes reliably, the SB-500 was enhanced with quantitative, real-time Tissue Change Monitoring (TCM) software. TCM uses pulse-echo ultrasound backscattered RF signals in 2D to estimate changes in the tissue properties caused by HIFU. The RF signal energy difference is calculated in selected frequency bands (pre and post HIFU) for each treatment site. The results are overlaid on the real-time ultrasound image in green, yellow and orange to represent low, medium and high degree of change in backscattered energy levels. The color mapping scheme was derived on measured temperature and backscattered RF signals from in vitro chicken tissue experiments. The TCM software was installed and tested in a clinical device to obtain human RF data. Post HIFU contrast enhanced MRI scans verified necrotic regions of the prostate. The color mapping success rate at higher HIFU power levels was 94% in the initial clinical test. Based on these results, TCM software has been released for wider usage. The clinical studies with TCM in Japan and The Bahamas have provided the following PSA (ng/ml) results. Japan (n = 97), PSA pre-treatment/post-treatment; minimum 0.7/0.0, maximum 76.0/4.73, median 6.89/0.07, standard deviation 11.19/0.62. The Bahamas (n = 59), minimum 0.4/0.0, maximum 13.0/1.4, median 4.7/0.1, standard deviation 2.8/0.3.

Detection of the Number of Changes in a Display in Working Memory

ERIC Educational Resources Information Center

Cowan, Nelson; Hardman, Kyle; Saults, J. Scott; Blume, Christopher L.; Clark, Katherine M.; Sunday, Mackenzie A.

2016-01-01

Here we examine a new task to assess working memory for visual arrays in which the participant must judge how many items changed from a studied array to a test array. As a clue to processing, on some trials in the first 2 experiments, participants carried out a metamemory judgment in which they were to decide how many items were in working memory.…

Retinal lesions induce fast intrinsic cortical plasticity in adult mouse visual system.

PubMed

Smolders, Katrien; Vreysen, Samme; Laramée, Marie-Eve; Cuyvers, Annemie; Hu, Tjing-Tjing; Van Brussel, Leen; Eysel, Ulf T; Nys, Julie; Arckens, Lutgarde

2016-09-01

Neuronal activity plays an important role in the development and structural-functional maintenance of the brain as well as in its life-long plastic response to changes in sensory stimulation. We characterized the impact of unilateral 15° laser lesions in the temporal lower visual field of the retina, on visually driven neuronal activity in the afferent visual pathway of adult mice using in situ hybridization for the activity reporter gene zif268. In the first days post-lesion, we detected a discrete zone of reduced zif268 expression in the contralateral hemisphere, spanning the border between the monocular segment of the primary visual cortex (V1) with extrastriate visual area V2M. We could not detect a clear lesion projection zone (LPZ) in areas lateral to V1 whereas medial to V2M, agranular and granular retrosplenial cortex showed decreased zif268 levels over their full extent. All affected areas displayed a return to normal zif268 levels, and this was faster in higher order visual areas than in V1. The lesion did, however, induce a permanent LPZ in the retinorecipient layers of the superior colliculus. We identified a retinotopy-based intrinsic capacity of adult mouse visual cortex to recover from restricted vision loss, with recovery speed reflecting the areal cortical magnification factor. Our observations predict incomplete visual field representations for areas lateral to V1 vs. lack of retinotopic organization for areas medial to V2M. The validation of this mouse model paves the way for future interrogations of cortical region- and cell-type-specific contributions to functional recovery, up to microcircuit level. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Terbium(III)/gold nanocluster conjugates: the development of a novel ratiometric fluorescent probe for mercury(II) and a paper-based visual sensor.

PubMed

Qi, Yan-Xia; Zhang, Min; Zhu, Anwei; Shi, Guoyue

2015-08-21

In this work, a novel ratiometric fluorescent probe was developed for rapid, highly accurate, sensitive and selective detection of mercury(II) (Hg(2+)) based on terbium(III)/gold nanocluster conjugates (Tb(3+)/BSA-AuNCs), in which bovine serum albumin capped gold nanoclusters (BSA-AuNCs) acted as the signal indicator and terbium(III) (Tb(3+)) was used as the build-in reference. Our proposed ratiometric fluorescent probe exhibited unique specificity toward Hg(2+) against other common environmentally and biologically important metal ions, and had high accuracy and sensitivity with a low detection limit of 1 nM. In addition, our proposed probe was effectively employed to detect Hg(2+) in the biological samples from the artificial Hg(2+)-infected rats. More significantly, an appealing paper-based visual sensor for Hg(2+) was designed by using filter paper embedded with Tb(3+)/BSA-AuNC conjugates, and we have further demonstrated its feasibility for facile fluorescent sensing of Hg(2+) in a visual format, in which only a handheld UV lamp is used. In the presence of Hg(2+), the paper-based visual sensor, illuminated by a handheld UV lamp, would undergo a distinct fluorescence color change from red to green, which can be readily observed with naked eyes even in trace Hg(2+) concentrations. The Tb(3+)/BSA-AuNC-derived paper-based visual sensor is cost-effective, portable, disposable and easy-to-use. This work unveiled a facile approach for accurate, sensitive and selective measuring of Hg(2+) with self-calibration.

Visual short-term memory guides infants' visual attention.

PubMed

Mitsven, Samantha G; Cantrell, Lisa M; Luck, Steven J; Oakes, Lisa M

2018-08-01

Adults' visual attention is guided by the contents of visual short-term memory (VSTM). Here we asked whether 10-month-old infants' (N = 41) visual attention is also guided by the information stored in VSTM. In two experiments, we modified the one-shot change detection task (Oakes, Baumgartner, Barrett, Messenger, & Luck, 2013) to create a simplified cued visual search task to ask how information stored in VSTM influences where infants look. A single sample item (e.g., a colored circle) was presented at fixation for 500 ms, followed by a brief (300 ms) retention interval and then a test array consisting of two items, one on each side of fixation. One item in the test array matched the sample stimulus and the other did not. Infants were more likely to look at the non-matching item than at the matching item, demonstrating that the information stored rapidly in VSTM guided subsequent looking behavior. Copyright © 2018 Elsevier B.V. All rights reserved.

Research on metallic material defect detection based on bionic sensing of human visual properties

NASA Astrophysics Data System (ADS)

Zhang, Pei Jiang; Cheng, Tao

2018-05-01

Due to the fact that human visual system can quickly lock the areas of interest in complex natural environment and focus on it, this paper proposes an eye-based visual attention mechanism by simulating human visual imaging features based on human visual attention mechanism Bionic Sensing Visual Inspection Model Method to Detect Defects of Metallic Materials in the Mechanical Field. First of all, according to the biologically visually significant low-level features, the mark of defect experience marking is used as the intermediate feature of simulated visual perception. Afterwards, SVM method was used to train the advanced features of visual defects of metal material. According to the weight of each party, the biometrics detection model of metal material defect, which simulates human visual characteristics, is obtained.

40 CFR 63.7330 - What are my monitoring requirements?

Code of Federal Regulations, 2010 CFR

2010-07-01

... relative change in particulate matter loadings using a bag leak detection system according to the... integrity of the baghouse through quarterly visual inspections of the baghouse interior for air leaks; and... must at all times monitor the pressure drop and water flow rate using a CPMS according to the...

Bees without flowers: before peak bloom, diverse native bees find insect-produced honeydew sugars

USDA-ARS?s Scientific Manuscript database

Bee foragers respond to complex visual, olfactory, and extrasensory cues to optimize searches for floral rewards. Their abilities to detect and distinguish floral colors, shapes, volatiles, and ultraviolet signals, and even gauge nectar availability from changes in floral humidity or electric fields...

Parietal substrates for dimensional effects in visual search: evidence from lesion-symptom mapping

PubMed Central

Humphreys, Glyn W.; Chechlacz, Magdalena

2013-01-01

In visual search, the detection of pop-out targets is facilitated when the target-defining dimension remains the same compared with when it changes across trials. We tested the brain regions necessary for these dimensional carry-over effects using a voxel-based morphometry study with brain-lesioned patients. Participants had to search for targets defined by either their colour (red or blue) or orientation (right- or left-tilted), and the target dimension either stayed the same or changed on consecutive trials. Twenty-five patients were categorized according to whether they showed an effect of dimensional change on search or not. The two groups did not differ with regard to their performance on several working memory tasks, and the dimensional carry-over effects were not correlated with working memory performance. With spatial, sustained attention and working memory deficits as well as lesion volume controlled, damage within the right inferior parietal lobule (the angular and supramarginal gyri) extending into the intraparietal sulcus was associated with an absence of dimensional carry-over (P < 0.001, cluster-level corrected for multiple comparisons). The data suggest that these regions of parietal cortex are necessary to implement attention shifting in the context of visual dimensional change. PMID:23404335

Monitoring evolution of HIFU-induced lesions with backscattered ultrasound

NASA Astrophysics Data System (ADS)

Anand, Ajay; Kaczkowski, Peter J.

2003-04-01

Backscattered radio frequency (rf) data from a modified commercial ultrasound scanner were collected in a series of in vitro experiments in which high intensity focused ultrasound (HIFU) was used to create lesions in freshly excised bovine liver tissue. Two signal processing approaches were used to visualize the temporal evolution of lesion formation. First, apparent tissue motion due to temperature rise was detected using cross-correlation techniques. Results indicate that differential processing of travel time can provide temperature change information throughout the therapy delivery phase and after HIFU has been turned off, over a relatively large spatial region. Second, changes in the frequency spectrum of rf echoes due to changes in the scattering properties of the heated region were observed well before the appearance of hyper-echogenic spots in the focal zone. Furthermore, the increase in attenuation in the lesion zone changes the measured backscatter spectrum from regions distal to it along the imaging beam. Both effects were visualized using spectral processing and display techniques that provide a color spatial map of these features for the clinician. Our results demonstrate potential for these ultrasound-based techniques in targeting and monitoring of HIFU therapy, and perhaps post-treatment visualization of HIFU-induced lesions.

Analysis of EEG Related Saccadic Eye Movement

NASA Astrophysics Data System (ADS)

Funase, Arao; Kuno, Yoshiaki; Okuma, Shigeru; Yagi, Tohru

Our final goal is to establish the model for saccadic eye movement that connects the saccade and the electroencephalogram(EEG). As the first step toward this goal, we recorded and analyzed the saccade-related EEG. In the study recorded in this paper, we tried detecting a certain EEG that is peculiar to the eye movement. In these experiments, each subject was instructed to point their eyes toward visual targets (LEDs) or the direction of the sound sources (buzzers). In the control cases, the EEG was recorded in the case of no eye movemens. As results, in the visual experiments, we found that the potential of EEG changed sharply on the occipital lobe just before eye movement. Furthermore, in the case of the auditory experiments, similar results were observed. In the case of the visual experiments and auditory experiments without eye movement, we could not observed the EEG changed sharply. Moreover, when the subject moved his/her eyes toward a right-side target, a change in EEG potential was found on the right occipital lobe. On the contrary, when the subject moved his/her eyes toward a left-side target, a sharp change in EEG potential was found on the left occipital lobe.

Background-Oriented Schlieren for Large-Scale and High-Speed Aerodynamic Phenomena

NASA Technical Reports Server (NTRS)

Mizukaki, Toshiharu; Borg, Stephen; Danehy, Paul M.; Murman, Scott M.; Matsumura, Tomoharu; Wakabayashi, Kunihiko; Nakayama, Yoshio

2015-01-01

Visualization of the flow field around a generic re-entry capsule in subsonic flow and shock wave visualization with cylindrical explosives have been conducted to demonstrate sensitivity and applicability of background-oriented schlieren (BOS) for field experiments. The wind tunnel experiment suggests that BOS with a fine-pixel imaging device has a density change detection sensitivity on the order of 10(sup -5) in subsonic flow. In a laboratory setup, the structure of the shock waves generated by explosives have been successfully reconstructed by a computed tomography method combined with BOS.

Adaptation mechanisms, eccentricity profiles, and clinical implementation of red-on-white perimetry.

PubMed

Zele, Andrew J; Dang, Trung M; O'Loughlin, Rebecca K; Guymer, Robyn H; Harper, Alex; Vingrys, Algis J

2008-05-01

To determine the visual adaptation and retinal eccentricity profiles for red flickering and static test stimuli and report a clinical implementation of these stimuli in visual perimetry. The adaptation profile for red-on-white perimetry stimuli was measured using a threshold vs. intensity (TvI) paradigm at 0 degree and 12 degrees eccentricity and by comparing the eccentricity-related sensitivity change for red and white, static, and flickering targets in young normal trichromats (n = 5) and a group of dichromats (n = 5). A group of older normal control observers (n = 30) were tested and retinal disease was evaluated in persons having age-related maculopathy (n = 35) and diabetes (n = 12). Adaptation and eccentricity profiles indicate red static and flickering targets are detected by two mechanisms in the paramacular region, and a single mechanism for >5 degrees eccentricity. The group data for the older normal observers has a high level of inter-observer variability with a generalized reduction in sensitivity across the entire visual field. Group data for the participants with age-related maculopathy show reduced sensitivities that were pronounced in the central retina. The group data for the diabetic observers showed sensitivities that were reduced at all eccentricities. The disease-related sensitivity decline was more apparent with red than white stimuli. The adaptation profile and change in sensitivity with retinal eccentricity for the red-on-white perimetric stimuli are consistent with two detection processes. In the macula, the putative detection mechanism is color-opponent with static targets and non-opponent with flickering targets. At peripheral field locations, the putative detection mechanism is non-opponent for both static and flicker targets. The long-wavelength stimuli are less affected by the preretinal absorption common to aging. Red-on-white static and flicker perimetry may be useful for monitoring retinal disease, revealing greater abnormalities compared with conventional white-on-white perimetry, especially in the macula where two detection mechanisms are found.

Emotion and anxiety potentiate the way attention alters visual appearance.

PubMed

Barbot, Antoine; Carrasco, Marisa

2018-04-12

The ability to swiftly detect and prioritize the processing of relevant information around us is critical for the way we interact with our environment. Selective attention is a key mechanism that serves this purpose, improving performance in numerous visual tasks. Reflexively attending to sudden information helps detect impeding threat or danger, a possible reason why emotion modulates the way selective attention affects perception. For instance, the sudden appearance of a fearful face potentiates the effects of exogenous (involuntary, stimulus-driven) attention on performance. Internal states such as trait anxiety can also modulate the impact of attention on early visual processing. However, attention does not only improve performance; it also alters the way visual information appears to us, e.g. by enhancing perceived contrast. Here we show that emotion potentiates the effects of exogenous attention on both performance and perceived contrast. Moreover, we found that trait anxiety mediates these effects, with stronger influences of attention and emotion in anxious observers. Finally, changes in performance and appearance correlated with each other, likely reflecting common attentional modulations. Altogether, our findings show that emotion and anxiety interact with selective attention to truly alter how we see.

The development of an indoor mobility course for the evaluation of electronic mobility aids for persons who are visually impaired.

PubMed

Roentgen, Uta R; Gelderblom, Gert Jan; de Witte, Luc P

2012-01-01

To develop a suitable mobility course for the assessment of mobility performance as part of a user evaluation of Electronic Mobility Aids (EMA) aimed at obstacle detection and orientation. A review of the literature led to a list of critical factors for the assessment of mobility performance of persons who are visually impaired. Based upon that list, method, test situations, and determining elements were selected and presented to Dutch orientation and mobility experts. Due to expert advice and a pilot study, minor changes were made and the final version was used for the evaluation of two EMA by eight persons who are visually impaired. The results of the literature study are summarized in an overview of critical factors for the assessment of the mobility performance of persons who are visually impaired. Applied to the requirements of the above mentioned user evaluation a replicable indoor mobility course has been described in detail and tested. Based upon evidence from literature an indoor mobility course has been developed, which was sensitive to assess differences in mobility incidents and obstacle detection when using an EMA compared to the regular mobility aid. Experts' opinion confirmed its face and content validity.

Automatic lip reading by using multimodal visual features

NASA Astrophysics Data System (ADS)

Takahashi, Shohei; Ohya, Jun

2013-12-01

Since long time ago, speech recognition has been researched, though it does not work well in noisy places such as in the car or in the train. In addition, people with hearing-impaired or difficulties in hearing cannot receive benefits from speech recognition. To recognize the speech automatically, visual information is also important. People understand speeches from not only audio information, but also visual information such as temporal changes in the lip shape. A vision based speech recognition method could work well in noisy places, and could be useful also for people with hearing disabilities. In this paper, we propose an automatic lip-reading method for recognizing the speech by using multimodal visual information without using any audio information such as speech recognition. First, the ASM (Active Shape Model) is used to track and detect the face and lip in a video sequence. Second, the shape, optical flow and spatial frequencies of the lip features are extracted from the lip detected by ASM. Next, the extracted multimodal features are ordered chronologically so that Support Vector Machine is performed in order to learn and classify the spoken words. Experiments for classifying several words show promising results of this proposed method.

A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images

NASA Astrophysics Data System (ADS)

Belghith, Akram; Bowd, Christopher; Weinreb, Robert N.; Zangwill, Linda M.

2014-03-01

Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new framework for detection of glaucoma progression using 3D SD-OCT images. In contrast to previous works that the retinal nerve fiber layer (RNFL) thickness measurement provided by commercially available spectral-domain optical coherence tomograph, we consider the whole 3D volume for change detection. To integrate a priori knowledge and in particular the spatial voxel dependency in the change detection map, we propose the use of the Markov Random Field to handle a such dependency. To accommodate the presence of false positive detection, the estimated change detection map is then used to classify a 3D SDOCT image into the "non-progressing" and "progressing" glaucoma classes, based on a fuzzy logic classifier. We compared the diagnostic performance of the proposed framework to existing methods of progression detection.

A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images.

PubMed

Belghith, Akram; Bowd, Christopher; Weinreb, Robert N; Zangwill, Linda M

2014-03-18

Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new framework for detection of glaucoma progression using 3D SD-OCT images. In contrast to previous works that the retinal nerve fiber layer (RNFL) thickness measurement provided by commercially available spectral-domain optical coherence tomograph, we consider the whole 3D volume for change detection. To integrate a priori knowledge and in particular the spatial voxel dependency in the change detection map, we propose the use of the Markov Random Field to handle a such dependency. To accommodate the presence of false positive detection, the estimated change detection map is then used to classify a 3D SDOCT image into the "non-progressing" and "progressing" glaucoma classes, based on a fuzzy logic classifier. We compared the diagnostic performance of the proposed framework to existing methods of progression detection.

A method to determine the impact of reduced visual function on nodule detection performance.

PubMed

Thompson, J D; Lança, C; Lança, L; Hogg, P

2017-02-01

In this study we aim to validate a method to assess the impact of reduced visual function and observer performance concurrently with a nodule detection task. Three consultant radiologists completed a nodule detection task under three conditions: without visual defocus (0.00 Dioptres; D), and with two different magnitudes of visual defocus (-1.00 D and -2.00 D). Defocus was applied with lenses and visual function was assessed prior to each image evaluation. Observers evaluated the same cases on each occasion; this comprised of 50 abnormal cases containing 1-4 simulated nodules (5, 8, 10 and 12 mm spherical diameter, 100 HU) placed within a phantom, and 25 normal cases (images containing no nodules). Data was collected under the free-response paradigm and analysed using Rjafroc. A difference in nodule detection performance would be considered significant at p < 0.05. All observers had acceptable visual function prior to beginning the nodule detection task. Visual acuity was reduced to an unacceptable level for two observers when defocussed to -1.00 D and for one observer when defocussed to -2.00 D. Stereoacuity was unacceptable for one observer when defocussed to -2.00 D. Despite unsatisfactory visual function in the presence of defocus we were unable to find a statistically significant difference in nodule detection performance (F(2,4) = 3.55, p = 0.130). A method to assess visual function and observer performance is proposed. In this pilot evaluation we were unable to detect any difference in nodule detection performance when using lenses to reduce visual function. Copyright © 2016 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Contrast discrimination, non-uniform patterns and change blindness.

PubMed Central

Scott-Brown, K C; Orbach, H S

1998-01-01

Change blindness--our inability to detect large changes in natural scenes when saccades, blinks and other transients interrupt visual input--seems to contradict psychophysical evidence for our exquisite sensitivity to contrast changes. Can the type of effects described as 'change blindness' be observed with simple, multi-element stimuli, amenable to psychophysical analysis? Such stimuli, composed of five mixed contrast elements, elicited a striking increase in contrast increment thresholds compared to those for an isolated element. Cue presentation prior to the stimulus substantially reduced thresholds, as for change blindness with natural scenes. On one hand, explanations for change blindness based on abstract and sketchy representations in short-term visual memory seem inappropriate for this low-level image property of contrast where there is ample evidence for exquisite performance on memory tasks. On the other hand, the highly increased thresholds for mixed contrast elements, and the decreased thresholds when a cue is present, argue against any simple early attentional or sensory explanation for change blindness. Thus, psychophysical results for very simple patterns cannot straightforwardly predict results even for the slightly more complicated patterns studied here. PMID:9872004

Processing changes across reading encounters.

PubMed

Levy, B A; Newell, S; Snyder, J; Timmins, K

1986-10-01

Five experiments examined changes in the processing of a text across reading encounters. Experiment 1 showed that reading speed increased systematically across encounters, with no loss in the extensiveness of analyses of the printed text, as indicated by the ability to detect nonword errors embedded within that passage. Experiment 2 replicated this improved reading fluency with experience and showed that it occurred even with typescript changes across trials, thus indicating that a primed visual operations explanation cannot account for the effect. The third and fourth experiments then extended the study of the familiarity effect to higher level processing, as indicated by the detection of word errors. Familiarity facilitated the detection of these violations at the syntactic-semantic levels. Finally, Experiment 5 showed that these higher level violations continued to be well detected over a series of reading encounters with the same text. The results indicate that prior experience improves reading speed, with no attenuation of analysis of the printed words or of the passage's message.

Change detection on UGV patrols with respect to a reference tour using VIS imagery

NASA Astrophysics Data System (ADS)

Müller, Thomas

2015-05-01

Autonomous driving robots (UGVs, Unmanned Ground Vehicles) equipped with visual-optical (VIS) cameras offer a high potential to automatically detect suspicious occurrences and dangerous or threatening situations on patrol. In order to explore this potential, the scene of interest is recorded first on a reference tour representing the 'everything okay' situation. On further patrols changes are detected with respect to the reference in a two step processing scheme. In the first step, an image retrieval is done to find the reference images that are closest to the current camera image on patrol. This is done efficiently based on precalculated image-to-image registrations of the reference by optimizing image overlap in a local reference search (after a global search when that is needed). In the second step, a robust spatio-temporal change detection is performed that widely compensates 3-D parallax according to variations of the camera position. Various results document the performance of the presented approach.

Synthetic Generation of Myocardial Blood-Oxygen-Level-Dependent MRI Time Series via Structural Sparse Decomposition Modeling

PubMed Central

Rusu, Cristian; Morisi, Rita; Boschetto, Davide; Dharmakumar, Rohan; Tsaftaris, Sotirios A.

2014-01-01

This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for Cardiac Phase-resolved Blood-Oxygen-Level-Dependent (CP–BOLD) MRI. CP–BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns. If transmurality of the defect is of interest pixel-level analysis is necessary and thus a higher precision in registration is required. Such precision is currently not available affecting the design and performance of the ischemia detection algorithms. In this work, to enable algorithmic developments of ischemia detection irrespective to registration accuracy, we propose an approach that generates synthetic pixel-level myocardial time series. We do this by (a) modeling the temporal changes in BOLD signal intensity based on sparse multi-component dictionary learning, whereby segmentally derived myocardial time series are extracted from canine experimental data to learn the model; and (b) demonstrating the resemblance between real and synthetic time series for validation purposes. We envision that the proposed approach has the capacity to accelerate development of tools for ischemia detection while markedly reducing experimental costs so that cardiac BOLD MRI can be rapidly translated into the clinical arena for the noninvasive assessment of ischemic heart disease. PMID:24691119

Synthetic generation of myocardial blood-oxygen-level-dependent MRI time series via structural sparse decomposition modeling.

PubMed

Rusu, Cristian; Morisi, Rita; Boschetto, Davide; Dharmakumar, Rohan; Tsaftaris, Sotirios A

2014-07-01

This paper aims to identify approaches that generate appropriate synthetic data (computer generated) for cardiac phase-resolved blood-oxygen-level-dependent (CP-BOLD) MRI. CP-BOLD MRI is a new contrast agent- and stress-free approach for examining changes in myocardial oxygenation in response to coronary artery disease. However, since signal intensity changes are subtle, rapid visualization is not possible with the naked eye. Quantifying and visualizing the extent of disease relies on myocardial segmentation and registration to isolate the myocardium and establish temporal correspondences and ischemia detection algorithms to identify temporal differences in BOLD signal intensity patterns. If transmurality of the defect is of interest pixel-level analysis is necessary and thus a higher precision in registration is required. Such precision is currently not available affecting the design and performance of the ischemia detection algorithms. In this work, to enable algorithmic developments of ischemia detection irrespective to registration accuracy, we propose an approach that generates synthetic pixel-level myocardial time series. We do this by 1) modeling the temporal changes in BOLD signal intensity based on sparse multi-component dictionary learning, whereby segmentally derived myocardial time series are extracted from canine experimental data to learn the model; and 2) demonstrating the resemblance between real and synthetic time series for validation purposes. We envision that the proposed approach has the capacity to accelerate development of tools for ischemia detection while markedly reducing experimental costs so that cardiac BOLD MRI can be rapidly translated into the clinical arena for the noninvasive assessment of ischemic heart disease.

A Fresh Look at Spatio-Temporal Remote Sensing Data: Data Formats, Processing Flow, and Visualization

NASA Astrophysics Data System (ADS)

Gens, R.

2017-12-01

With increasing number of experimental and operational satellites in orbit, remote sensing based mapping and monitoring of the dynamic Earth has entered into the realm of `big data'. Just the Landsat series of satellites provide a near continuous archive of 45 years of data. The availability of such spatio-temporal datasets has created opportunities for long-term monitoring diverse features and processes operating on the Earth's terrestrial and aquatic systems. Processes such as erosion, deposition, subsidence, uplift, evapotranspiration, urbanization, land-cover regime shifts can not only be monitored and change can be quantified using time-series data analysis. This unique opportunity comes with new challenges in management, analysis, and visualization of spatio-temporal datasets. Data need to be stored in a user-friendly format, and relevant metadata needs to be recorded, to allow maximum flexibility for data exchange and use. Specific data processing workflows need to be defined to support time-series analysis for specific applications. Value-added data products need to be generated keeping in mind the needs of the end-users, and using best practices in complex data visualization. This presentation systematically highlights the various steps for preparing spatio-temporal remote sensing data for time series analysis. It showcases a prototype workflow for remote sensing based change detection that can be generically applied while preserving the application-specific fidelity of the datasets. The prototype includes strategies for visualizing change over time. This has been exemplified using a time-series of optical and SAR images for visualizing the changing glacial, coastal, and wetland landscapes in parts of Alaska.

Development of the dichlorvos-ammonia (DV-AM) method for the visual detection of aflatoxigenic fungi.

PubMed

Yabe, Kimiko; Hatabayashi, Hidemi; Ikehata, Akifumi; Zheng, Yazhi; Kushiro, Masayo

2015-12-01

Aflatoxins (AFs) are carcinogenic and toxic secondary metabolites produced mainly by Aspergillus flavus and Aspergillus parasiticus. To monitor and regulate the AF contamination of crops, a sensitive and precise detection method for these toxigenic fungi in environments is necessary. We herein developed a novel visual detection method, the dichlorvos-ammonia (DV-AM) method, for identifying AF-producing fungi using DV and AM vapor on agar culture plates, in which DV inhibits the esterase in AF biosynthesis, causing the accumulation of anthraquinone precursors (versiconal hemiacetal acetate and versiconol acetate) of AFs in mycelia on the agar plate, followed by a change in the color of the colonies from light yellow to brilliant purple-red by the AM vapor treatment. We also investigated the appropriate culture conditions to increase the color intensity. It should be noted that other species producing the same precursors of AFs such as Aspergillus nidulans and Aspergillus versicolor could be discriminated from the Aspergillus section Flavi based on the differences of their phenotypes. The DV-AM method was also useful for the isolation of nonaflatoxigenic fungi showing no color change, for screening microorganisms that inhibit the AF production by fungi, and for the characterization of the fungi infecting corn kernels. Thus, the DV-AM method can provide a highly sensitive and visible indicator for the detection of aflatoxigenic fungi.

Visual motion detection and habitat preference in Anolis lizards.

PubMed

Steinberg, David S; Leal, Manuel

2016-11-01

The perception of visual stimuli has been a major area of inquiry in sensory ecology, and much of this work has focused on coloration. However, for visually oriented organisms, the process of visual motion detection is often equally crucial to survival and reproduction. Despite the importance of motion detection to many organisms' daily activities, the degree of interspecific variation in the perception of visual motion remains largely unexplored. Furthermore, the factors driving this potential variation (e.g., ecology or evolutionary history) along with the effects of such variation on behavior are unknown. We used a behavioral assay under laboratory conditions to quantify the visual motion detection systems of three species of Puerto Rican Anolis lizard that prefer distinct structural habitat types. We then compared our results to data previously collected for anoles from Cuba, Puerto Rico, and Central America. Our findings indicate that general visual motion detection parameters are similar across species, regardless of habitat preference or evolutionary history. We argue that these conserved sensory properties may drive the evolution of visual communication behavior in this clade.

Confocal laser feedback tomography for skin cancer detection

PubMed Central

Mowla, Alireza; Du, Benjamin Wensheng; Taimre, Thomas; Bertling, Karl; Wilson, Stephen; Soyer, H. Peter; Rakić, Aleksandar D.

2017-01-01

Tomographic imaging of soft tissue such as skin has a potential role in cancer detection. The penetration of infrared wavelengths makes a confocal approach based on laser feedback interferometry feasible. We present a compact system using a semiconductor laser as both transmitter and receiver. Numerical and physical models based on the known optical properties of keratinocyte cancers were developed. We validated the technique on three phantoms containing macro-structural changes in optical properties. Experimental results were in agreement with numerical simulations and structural changes were evident which would permit discrimination of healthy tissue and tumour. Furthermore, cancer type discrimination was also able to be visualized using this imaging technique. PMID:28966845

Confocal laser feedback tomography for skin cancer detection.

PubMed

Mowla, Alireza; Du, Benjamin Wensheng; Taimre, Thomas; Bertling, Karl; Wilson, Stephen; Soyer, H Peter; Rakić, Aleksandar D

2017-09-01

Tomographic imaging of soft tissue such as skin has a potential role in cancer detection. The penetration of infrared wavelengths makes a confocal approach based on laser feedback interferometry feasible. We present a compact system using a semiconductor laser as both transmitter and receiver. Numerical and physical models based on the known optical properties of keratinocyte cancers were developed. We validated the technique on three phantoms containing macro-structural changes in optical properties. Experimental results were in agreement with numerical simulations and structural changes were evident which would permit discrimination of healthy tissue and tumour. Furthermore, cancer type discrimination was also able to be visualized using this imaging technique.

Effects of spatial cues on color-change detection in humans

PubMed Central

Herman, James P.; Bogadhi, Amarender R.; Krauzlis, Richard J.

2015-01-01

Studies of covert spatial attention have largely used motion, orientation, and contrast stimuli as these features are fundamental components of vision. The feature dimension of color is also fundamental to visual perception, particularly for catarrhine primates, and yet very little is known about the effects of spatial attention on color perception. Here we present results using novel dynamic color stimuli in both discrimination and color-change detection tasks. We find that our stimuli yield comparable discrimination thresholds to those obtained with static stimuli. Further, we find that an informative spatial cue improves performance and speeds response time in a color-change detection task compared with an uncued condition, similar to what has been demonstrated for motion, orientation, and contrast stimuli. Our results demonstrate the use of dynamic color stimuli for an established psychophysical task and show that color stimuli are well suited to the study of spatial attention. PMID:26047359

Impact of LANDSAT MSS sensor differences on change detection analysis

NASA Technical Reports Server (NTRS)

Likens, W. C.; Wrigley, R. C.

1983-01-01

Some 512 by 512 pixel subwindows for simultaneously acquired scene pairs obtained by LANDSAT 2,3 and 4 multispectral band scanners were coregistered using LANDSAT 4 scenes as the base to which the other images were registered. Scattergrams between the coregistered scenes (a form of contingency analysis) were used to radiometrically compare data from the various sensors. Mode values were derived and used to visually fit a linear regression. Root mean square errors of the registration varied between .1 and 1.5 pixels. There appear to be no major problem preventing the use of LANDSAT 4 MSS with previous MSS sensors for change detection, provided the noise interference can be removed or minimized. Data normalizations for change detection should be based on the data rather than solely on calibration information. This allows simultaneous normalization of the atmosphere as well as the radiometry.

Blue Whale Visual and Acoustic Encounter Rates in the Southern California Bight

DTIC Science & Technology

2007-07-01

blue whale (Balaenoptera musculus) visual and acoustic encounter rates was quantitatively evaluated using hourly counts of detected whales during...surveys occurring in April, there were visual and acoustic detections of blue whales in all surveyed months and regions. Encounter rate is...difference between acoustic encounters of singing whales and visual encounters suggest seasonal variation in the ability of each method to detect blue

High-resolution remotely sensed small target detection by imitating fly visual perception mechanism.

PubMed

Huang, Fengchen; Xu, Lizhong; Li, Min; Tang, Min

2012-01-01

The difficulty and limitation of small target detection methods for high-resolution remote sensing data have been a recent research hot spot. Inspired by the information capture and processing theory of fly visual system, this paper endeavors to construct a characterized model of information perception and make use of the advantages of fast and accurate small target detection under complex varied nature environment. The proposed model forms a theoretical basis of small target detection for high-resolution remote sensing data. After the comparison of prevailing simulation mechanism behind fly visual systems, we propose a fly-imitated visual system method of information processing for high-resolution remote sensing data. A small target detector and corresponding detection algorithm are designed by simulating the mechanism of information acquisition, compression, and fusion of fly visual system and the function of pool cell and the character of nonlinear self-adaption. Experiments verify the feasibility and rationality of the proposed small target detection model and fly-imitated visual perception method.

Colour Terms Affect Detection of Colour and Colour-Associated Objects Suppressed from Visual Awareness

PubMed Central

Forder, Lewis; Taylor, Olivia; Mankin, Helen; Scott, Ryan B.; Franklin, Anna

2016-01-01

The idea that language can affect how we see the world continues to create controversy. A potentially important study in this field has shown that when an object is suppressed from visual awareness using continuous flash suppression (a form of binocular rivalry), detection of the object is differently affected by a preceding word prime depending on whether the prime matches or does not match the object. This may suggest that language can affect early stages of vision. We replicated this paradigm and further investigated whether colour terms likewise influence the detection of colours or colour-associated object images suppressed from visual awareness by continuous flash suppression. This method presents rapidly changing visual noise to one eye while the target stimulus is presented to the other. It has been shown to delay conscious perception of a target for up to several minutes. In Experiment 1 we presented greyscale photos of objects. They were either preceded by a congruent object label, an incongruent label, or white noise. Detection sensitivity (d’) and hit rates were significantly poorer for suppressed objects preceded by an incongruent label compared to a congruent label or noise. In Experiment 2, targets were coloured discs preceded by a colour term. Detection sensitivity was significantly worse for suppressed colour patches preceded by an incongruent colour term as compared to a congruent term or white noise. In Experiment 3 targets were suppressed greyscale object images preceded by an auditory presentation of a colour term. On congruent trials the colour term matched the object’s stereotypical colour and on incongruent trials the colour term mismatched. Detection sensitivity was significantly poorer on incongruent trials than congruent trials. Overall, these findings suggest that colour terms affect awareness of coloured stimuli and colour- associated objects, and provide new evidence for language-perception interaction in the brain. PMID:27023274

Colour Terms Affect Detection of Colour and Colour-Associated Objects Suppressed from Visual Awareness.

PubMed

Forder, Lewis; Taylor, Olivia; Mankin, Helen; Scott, Ryan B; Franklin, Anna

2016-01-01

The idea that language can affect how we see the world continues to create controversy. A potentially important study in this field has shown that when an object is suppressed from visual awareness using continuous flash suppression (a form of binocular rivalry), detection of the object is differently affected by a preceding word prime depending on whether the prime matches or does not match the object. This may suggest that language can affect early stages of vision. We replicated this paradigm and further investigated whether colour terms likewise influence the detection of colours or colour-associated object images suppressed from visual awareness by continuous flash suppression. This method presents rapidly changing visual noise to one eye while the target stimulus is presented to the other. It has been shown to delay conscious perception of a target for up to several minutes. In Experiment 1 we presented greyscale photos of objects. They were either preceded by a congruent object label, an incongruent label, or white noise. Detection sensitivity (d') and hit rates were significantly poorer for suppressed objects preceded by an incongruent label compared to a congruent label or noise. In Experiment 2, targets were coloured discs preceded by a colour term. Detection sensitivity was significantly worse for suppressed colour patches preceded by an incongruent colour term as compared to a congruent term or white noise. In Experiment 3 targets were suppressed greyscale object images preceded by an auditory presentation of a colour term. On congruent trials the colour term matched the object's stereotypical colour and on incongruent trials the colour term mismatched. Detection sensitivity was significantly poorer on incongruent trials than congruent trials. Overall, these findings suggest that colour terms affect awareness of coloured stimuli and colour- associated objects, and provide new evidence for language-perception interaction in the brain.

Evaluation of four novel isothermal amplification assays towards simple and rapid genotyping of chloroquine resistant Plasmodium falciparum.

PubMed

Chahar, Madhvi; Anvikar, Anup; Dixit, Rajnikant; Valecha, Neena

2018-07-01

Loop mediated isothermal amplification (LAMP) assay is sensitive, prompt, high throughput and field deployable technique for nucleic acid amplification under isothermal conditions. In this study, we have developed and optimized four different visualization methods of loop-mediated isothermal amplification (LAMP) assay to detect Pfcrt K76T mutants of P. falciparum and compared their important features for one-pot in-field applications. Even though all the four tested LAMP methods could successfully detect K76T mutants of P. falciparum, however considering the time, safety, sensitivity, cost and simplicity, the malachite green and HNB based methods were found more efficient. Among four different visual dyes uses to detect LAMP products accurately, hydroxynaphthol blue and malachite green could produce long stable color change and brightness in a close tube-based approach to prevent cross-contamination risk. Our results indicated that the LAMP offers an interesting novel and convenient best method for the rapid, sensitive, cost-effective, and fairly user friendly tool for detection of K76T mutants of P. falciparum and therefore presents an alternative to PCR-based assays. Based on our comparative analysis, better field based LAMP visualization method can be chosen easily for the monitoring of other important drug targets (Kelch13 propeller region). Copyright © 2018 Elsevier Inc. All rights reserved.

The accuracy of confrontation visual field test in comparison with automated perimetry.

PubMed Central

Johnson, L. N.; Baloh, F. G.

1991-01-01

The accuracy of confrontation visual field testing was determined for 512 visual fields using automated static perimetry as the reference standard. The sensitivity of confrontation testing excluding patchy defects was 40% for detecting anterior visual field defects, 68.3% for posterior defects, and 50% for both anterior and posterior visual field defects combined. The sensitivity within each group varied depending on the type of visual field defect encountered. Confrontation testing had a high sensitivity (75% to 100%) for detecting altitudinal visual loss, central/centrocecal scotoma, and homonymous hemianopsia. Confrontation testing was fairly insensitive (20% to 50% sensitivity) for detecting arcuate scotoma and bitemporal hemianopsia. The specificity of confrontation testing was high at 93.4%. The high positive predictive value (72.6%) and negative predictive value (75.7%) would indicate that visual field defects identified during confrontation testing are often true visual field defects. However, the many limitations of confrontation testing should be remembered, particularly its low sensitivity for detecting visual field loss associated with parasellar tumors, glaucoma, and compressive optic neuropathies. PMID:1800764

Age-Related Changes in the Ability to Switch between Temporal and Spatial Attention

PubMed Central

Callaghan, Eleanor; Holland, Carol; Kessler, Klaus

2017-01-01

Background: Identifying age-related changes in cognition that contribute towards reduced driving performance is important for the development of interventions to improve older adults’ driving and prolong the time that they can continue to drive. While driving, one is often required to switch from attending to events changing in time, to distribute attention spatially. Although there is extensive research into both spatial attention and temporal attention and how these change with age, the literature on switching between these modalities of attention is limited within any age group. Methods: Age groups (21–30, 40–49, 50–59, 60–69 and 70+ years) were compared on their ability to switch between detecting a target in a rapid serial visual presentation (RSVP) stream and detecting a target in a visual search display. To manipulate the cost of switching, the target in the RSVP stream was either the first item in the stream (Target 1st), towards the end of the stream (Target Mid), or absent from the stream (Distractor Only). Visual search response times and accuracy were recorded. Target 1st trials behaved as no-switch trials, as attending to the remaining stream was not necessary. Target Mid and Distractor Only trials behaved as switch trials, as attending to the stream to the end was required. Results: Visual search response times (RTs) were longer on “Target Mid” and “Distractor Only” trials in comparison to “Target 1st” trials, reflecting switch-costs. Larger switch-costs were found in both the 40–49 and 60–69 years group in comparison to the 21–30 years group when switching from the Target Mid condition. Discussion: Findings warrant further exploration as to whether there are age-related changes in the ability to switch between these modalities of attention while driving. If older adults display poor performance when switching between temporal and spatial attention while driving, then the development of an intervention to preserve and improve this ability would be beneficial. PMID:28261088

The effects of acute alcohol exposure on the response properties of neurons in visual cortex area 17 of cats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Bo; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Science, Beijing 100101; Xia Jing

Physiological and behavioral studies have demonstrated that a number of visual functions such as visual acuity, contrast sensitivity, and motion perception can be impaired by acute alcohol exposure. The orientation- and direction-selective responses of cells in primary visual cortex are thought to participate in the perception of form and motion. To investigate how orientation selectivity and direction selectivity of neurons are influenced by acute alcohol exposure in vivo, we used the extracellular single-unit recording technique to examine the response properties of neurons in primary visual cortex (A17) of adult cats. We found that alcohol reduces spontaneous activity, visual evoked unitmore » responses, the signal-to-noise ratio, and orientation selectivity of A17 cells. In addition, small but detectable changes in both the preferred orientation/direction and the bandwidth of the orientation tuning curve of strongly orientation-biased A17 cells were observed after acute alcohol administration. Our findings may provide physiological evidence for some alcohol-related deficits in visual function observed in behavioral studies.« less

A new rhodamine-based colorimetric chemosensor for naked-eye detection of Cu2 + in aqueous solution

NASA Astrophysics Data System (ADS)

Hu, Yang; Zhang, Jing; Lv, Yuan-Zheng; Huang, Xiao-Huan; Hu, Sheng-li

2016-03-01

A new colorimetric probe 1 based on rhodamine B lactam was developed for naked-eye detection of Cu2 +. The optical feature of 1 for Cu2 + was investigated by UV-vis absorption spectroscopy. Upon the addition of Cu2 +, the 1 displayed a distinct color change from colorless to pink, which can be directly detected by the naked eye. The stoichiometry of 1 to Cu2 + complex was found to be 1:1 and the naked-eye detection limit was determined as low as 2 μM. The results suggest that the probe 1 may provide a convenient method for visual detection of Cu2 + with high sensitivity.

Pre- and postprandial variation in implicit attention to food images reflects appetite and sensory-specific satiety.

PubMed

Davidson, Graeme R; Giesbrecht, Timo; Thomas, Anna M; Kirkham, Tim C

2018-06-01

Implicit attentional processes are biased toward food-related stimuli, with the extent of that bias reflecting relative motivation to eat. These interactions have typically been investigated by comparisons between fasted and sated individuals. In this study, temporal changes in implicit attention to food were assessed in relation to natural, spontaneous changes in appetite occurring before and after an anticipated midday meal. Non-fasted adults performed an emotional blink of attention (EBA) task at intervals, before and after consuming preferred, pre-selected sandwiches to satiety. Participants were required to detect targets within a rapid visual stream, presented after task-irrelevant food (preferred or non-preferred sandwiches, or desserts) or non-food distractor images. All categories of food distractor preferentially captured attention even when appetite levels were low, but became more distracting as appetite increased preprandially, reducing task accuracy maximally as hunger peaked before lunch. Postprandially, attentional capture was markedly reduced for images of the specific sandwich type consumed and, to a lesser extent, for images of other sandwich types that had not been eaten. Attentional capture by images of desserts was unaffected by satiation. These findings support an important role of selective visual attention in the guidance of motivated behaviour. Naturalistic, meal-related changes in appetite are accompanied by changes in implicit attention to visual food stimuli that are easily detected using the EBA paradigm. Preprandial enhancement of attention capture by food cues likely reflects increases in the incentive motivational value of all food stimuli, perhaps providing an implicit index of wanting. Postprandial EBA responses confirm that satiation on a particular food results in relative inattention to that food, supporting an important attentional component in the operation of sensory-specific satiety. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Audio-visual speech processing in age-related hearing loss: Stronger integration and increased frontal lobe recruitment.

PubMed

Rosemann, Stephanie; Thiel, Christiane M

2018-07-15

Hearing loss is associated with difficulties in understanding speech, especially under adverse listening conditions. In these situations, seeing the speaker improves speech intelligibility in hearing-impaired participants. On the neuronal level, previous research has shown cross-modal plastic reorganization in the auditory cortex following hearing loss leading to altered processing of auditory, visual and audio-visual information. However, how reduced auditory input effects audio-visual speech perception in hearing-impaired subjects is largely unknown. We here investigated the impact of mild to moderate age-related hearing loss on processing audio-visual speech using functional magnetic resonance imaging. Normal-hearing and hearing-impaired participants performed two audio-visual speech integration tasks: a sentence detection task inside the scanner and the McGurk illusion outside the scanner. Both tasks consisted of congruent and incongruent audio-visual conditions, as well as auditory-only and visual-only conditions. We found a significantly stronger McGurk illusion in the hearing-impaired participants, which indicates stronger audio-visual integration. Neurally, hearing loss was associated with an increased recruitment of frontal brain areas when processing incongruent audio-visual, auditory and also visual speech stimuli, which may reflect the increased effort to perform the task. Hearing loss modulated both the audio-visual integration strength measured with the McGurk illusion and brain activation in frontal areas in the sentence task, showing stronger integration and higher brain activation with increasing hearing loss. Incongruent compared to congruent audio-visual speech revealed an opposite brain activation pattern in left ventral postcentral gyrus in both groups, with higher activation in hearing-impaired participants in the incongruent condition. Our results indicate that already mild to moderate hearing loss impacts audio-visual speech processing accompanied by changes in brain activation particularly involving frontal areas. These changes are modulated by the extent of hearing loss. Copyright © 2018 Elsevier Inc. All rights reserved.

Differential impact of partial cortical blindness on gaze strategies when sitting and walking - an immersive virtual reality study

PubMed Central

Iorizzo, Dana B.; Riley, Meghan E.; Hayhoe, Mary; Huxlin, Krystel R.

2011-01-01

The present experiments aimed to characterize the visual performance of subjects with long-standing, unilateral cortical blindness when walking in a naturalistic, virtual environment. Under static, seated testing conditions, cortically blind subjects are known to exhibit compensatory eye movement strategies. However, they still complain of significant impairment in visual detection during navigation. To assess whether this is due to a change in compensatory eye movement strategy between sitting and walking, we measured eye and head movements in subjects asked to detect peripherally-presented, moving basketballs. When seated, cortically blind subjects detected ~80% of balls, while controls detected almost all balls. Seated blind subjects did not make larger head movements than controls, but they consistently biased their fixation distribution towards their blind hemifield. When walking, head movements were similar in the two groups, but the fixation bias decreased to the point that fixation distribution in cortically blind subjects became similar to that in controls - with one major exception: at the time of basketball appearance, walking controls looked primarily at the far ground, in upper quadrants of the virtual field of view; cortically blind subjects looked significantly more at the near ground, in lower quadrants of the virtual field. Cortically blind subjects detected only 58% of the balls when walking while controls detected ~90%. Thus, the adaptive gaze strategies adopted by cortically blind individuals as a compensation for their visual loss are strongest and most effective when seated and stationary. Walking significantly alters these gaze strategies in a way that seems to favor walking performance, but impairs peripheral target detection. It is possible that this impairment underlies the experienced difficulty of those with cortical blindness when navigating in real life. PMID:21414339

Differential impact of partial cortical blindness on gaze strategies when sitting and walking - an immersive virtual reality study.

PubMed

Iorizzo, Dana B; Riley, Meghan E; Hayhoe, Mary; Huxlin, Krystel R

2011-05-25

The present experiments aimed to characterize the visual performance of subjects with long-standing, unilateral cortical blindness when walking in a naturalistic, virtual environment. Under static, seated testing conditions, cortically blind subjects are known to exhibit compensatory eye movement strategies. However, they still complain of significant impairment in visual detection during navigation. To assess whether this is due to a change in compensatory eye movement strategy between sitting and walking, we measured eye and head movements in subjects asked to detect peripherally-presented, moving basketballs. When seated, cortically blind subjects detected ∼80% of balls, while controls detected almost all balls. Seated blind subjects did not make larger head movements than controls, but they consistently biased their fixation distribution towards their blind hemifield. When walking, head movements were similar in the two groups, but the fixation bias decreased to the point that fixation distribution in cortically blind subjects became similar to that in controls - with one major exception: at the time of basketball appearance, walking controls looked primarily at the far ground, in upper quadrants of the virtual field of view; cortically blind subjects looked significantly more at the near ground, in lower quadrants of the virtual field. Cortically blind subjects detected only 58% of the balls when walking while controls detected ∼90%. Thus, the adaptive gaze strategies adopted by cortically blind individuals as a compensation for their visual loss are strongest and most effective when seated and stationary. Walking significantly alters these gaze strategies in a way that seems to favor walking performance, but impairs peripheral target detection. It is possible that this impairment underlies the experienced difficulty of those with cortical blindness when navigating in real life. Copyright © 2011 Elsevier Ltd. All rights reserved.

Visual detection of Brucella in bovine biological samples using DNA-activated gold nanoparticles

PubMed Central

Kumar, Satish; Kaur, Gurpreet; Ali, Syed Atif; Shrivastava, Sameer; Gupta, Praveen K.; Cooper, Jonathan M.; Chaudhuri, Pallab

2017-01-01

Brucellosis is a bacterial disease, which, although affecting cattle primarily, has been associated with human infections, making its detection an important challenge. The existing gold standard diagnosis relies on the culture of bacteria which is a lengthy and costly process, taking up to 45 days. New technologies based on molecular diagnosis have been proposed, either through dip-stick, immunological assays, which have limited specificity, or using nucleic acid tests, which enable to identify the pathogen, but are impractical for use in the field, where most of the reservoir cases are located. Here we demonstrate a new test based on hybridization assays with metal nanoparticles, which, upon detection of a specific pathogen-derived DNA sequence, yield a visual colour change. We characterise the components used in the assay with a range of analytical techniques and show sensitivities down to 1000 cfu/ml for the detection of Brucella. Finally, we demonstrate that the assay works in a range of bovine samples including semen, milk and urine, opening up the potential for its use in the field, in low-resource settings. PMID:28719613

Low picomolar, instrument-free visual detection of mercury and silver ions using low-cost programmable nanoprobes

PubMed Central

Rana, Muhit; Balcioglu, Mustafa; Robertson, Neil M.; Hizir, Mustafa Salih; Yumak, Sumeyra

2017-01-01

The EPA's recommended maximum allowable level of inorganic mercury in drinking water is 2 ppb (10 nM). To our knowledge, the most sensitive colorimetric mercury sensor reported to date has a limit of detection (LOD) of 800 pM. Here, we report an instrument-free and highly practical colorimetric methodology, which enables detection of as low as 2 ppt (10 pM) of mercury and/or silver ions with the naked eye using a gold nanoprobe. Synthesis of the nanoprobe costs less than $1.42, which is enough to perform 200 tests in a microplate; less than a penny for each test. We have demonstrated the detection of inorganic mercury from water, soil and urine samples. The assay takes about four hours and the color change is observed within minutes after the addition of the last required element of the assay. The nanoprobe is highly programmable which allows for the detection of mercury and/or silver ions separately or simultaneously by changing only a single parameter of the assay. This highly sensitive approach for the visual detection relies on the combination of the signal amplification features of the hybridization chain reaction with the plasmonic properties of the gold nanoparticles. Considering that heavy metal ion contamination of natural resources is a major challenge and routine environmental monitoring is needed, yet time-consuming, this colorimetric approach may be instrumental for on-site heavy metal ion detection. Since the color transition can be measured in a variety of formats including using the naked eye, a simple UV-Vis spectrophotometer, or recording using mobile phone apps for future directions, our cost-efficient assay and method have the potential to be translated into the field. PMID:28451261

Visual Sensitivities and Discriminations and Their Roles in Aviation.

DTIC Science & Technology

1986-03-01

D. Low contrast letter charts in early diabetic retinopathy , octrlar hypertension, glaucoma and Parkinson’s disease. Br J Ophthalmol, 1984, 68, 885...to detect a camouflaged object that was visible only when moving, and compared these data with similar measurements for conventional objects that were...3) Compare visual detection (i.e. visual acquisition) of camouflaged objects whose edges are defined by velocity differences with visual detection

Sub-Chronic Neuropathological and Biochemical Changes in Mouse Visual System after Repetitive Mild Traumatic Brain Injury

PubMed Central

Tzekov, Radouil; Dawson, Clint; Orlando, Megan; Mouzon, Benoit; Reed, Jon; Evans, James; Crynen, Gogce; Mullan, Michael; Crawford, Fiona

2016-01-01

Repetitive mild traumatic brain injury (r-mTBI) results in neuropathological and biochemical consequences in the human visual system. Using a recently developed mouse model of r-mTBI, with control mice receiving repetitive anesthesia alone (r-sham) we assessed the effects on the retina and optic nerve using histology, immunohistochemistry, proteomic and lipidomic analyses at 3 weeks post injury. Retina tissue was used to determine retinal ganglion cell (RGC) number, while optic nerve tissue was examined for cellularity, myelin content, protein and lipid changes. Increased cellularity and areas of demyelination were clearly detectable in optic nerves in r-mTBI, but not in r-sham. These changes were accompanied by a ~25% decrease in the total number of Brn3a-positive RGCs. Proteomic analysis of the optic nerves demonstrated various changes consistent with a negative effect of r-mTBI on major cellular processes like depolymerization of microtubules, disassembly of filaments and loss of neurons, manifested by decrease of several proteins, including neurofilaments (NEFH, NEFM, NEFL), tubulin (TUBB2A, TUBA4A), microtubule-associated proteins (MAP1A, MAP1B), collagen (COL6A1, COL6A3) and increased expression of other proteins, including heat shock proteins (HSP90B1, HSPB1), APOE and cathepsin D. Lipidomic analysis showed quantitative changes in a number of phospholipid species, including a significant increase in the total amount of lysophosphatidylcholine (LPC), including the molecular species 16:0, a known demyelinating agent. The overall amount of some ether phospholipids, like ether LPC, ether phosphatidylcholine and ether lysophosphatidylethanolamine were also increased, while the majority of individual molecular species of ester phospholipids, like phosphatidylcholine and phosphatidylethanolamine, were decreased. Results from the biochemical analysis correlate well with changes detected by histological and immunohistochemical methods and indicate the involvement of several important molecular pathways. This will allow future identification of therapeutic targets for improving the visual consequences of r-mTBI. PMID:27088355

Differences in change blindness to real-life scenes in adults with autism spectrum conditions.

PubMed

Ashwin, Chris; Wheelwright, Sally; Baron-Cohen, Simon

2017-01-01

People often fail to detect large changes to visual scenes following a brief interruption, an effect known as 'change blindness'. People with autism spectrum conditions (ASC) have superior attention to detail and better discrimination of targets, and often notice small details that are missed by others. Together these predict people with autism should show enhanced perception of changes in simple change detection paradigms, including reduced change blindness. However, change blindness studies to date have reported mixed results in ASC, which have sometimes included no differences to controls or even enhanced change blindness. Attenuated change blindness has only been reported to date in ASC in children and adolescents, with no study reporting reduced change blindness in adults with ASC. The present study used a change blindness flicker task to investigate the detection of changes in images of everyday life in adults with ASC (n = 22) and controls (n = 22) using a simple change detection task design and full range of original scenes as stimuli. Results showed the adults with ASC had reduced change blindness compared to adult controls for changes to items of marginal interest in scenes, with no group difference for changes to items of central interest. There were no group differences in overall response latencies to correctly detect changes nor in the overall number of missed detections in the experiment. However, the ASC group showed greater missed changes for marginal interest changes of location, showing some evidence of greater change blindness as well. These findings show both reduced change blindness to marginal interest changes in ASC, based on response latencies, as well as greater change blindness to changes of location of marginal interest items, based on detection rates. The findings of reduced change blindness are consistent with clinical reports that people with ASC often notice small changes to less salient items within their environment, and are in-line with theories of enhanced local processing and greater attention to detail in ASC. The findings of lower detection rates for one of the marginal interest conditions may be related to problems in shifting attention or an overly focused attention spotlight.

Neural correlates of individual performance differences in resolving perceptual conflict.

PubMed

Labrenz, Franziska; Themann, Maria; Wascher, Edmund; Beste, Christian; Pfleiderer, Bettina

2012-01-01

Attentional mechanisms are a crucial prerequisite to organize behavior. Most situations may be characterized by a 'competition' between salient, but irrelevant stimuli and less salient, relevant stimuli. In such situations top-down and bottom-up mechanisms interact with each other. In the present fMRI study, we examined how interindividual differences in resolving situations of perceptual conflict are reflected in brain networks mediating attentional selection. Doing so, we employed a change detection task in which subjects had to detect luminance changes in the presence and absence of competing distractors. The results show that good performers presented increased activation in the orbitofrontal cortex (BA 11), anterior cingulate (BA 25), inferior parietal lobule (BA 40) and visual areas V2 and V3 but decreased activation in BA 39. This suggests that areas mediating top-down attentional control are stronger activated in this group. Increased activity in visual areas reflects distinct neuronal enhancement relating to selective attentional mechanisms in order to solve the perceptual conflict. Opposed to good performers, brain areas activated by poor performers comprised the left inferior parietal lobule (BA 39) and fronto-parietal and visual regions were continuously deactivated, suggesting that poor performers perceive stronger conflict than good performers. Moreover, the suppression of neural activation in visual areas might indicate a strategy of poor performers to inhibit the processing of the irrelevant non-target feature. These results indicate that high sensitivity in perceptual areas and increased attentional control led to less conflict in stimulus processing and consequently to higher performance in competitive attentional selection.

A Bayesian Account of Visual-Vestibular Interactions in the Rod-and-Frame Task.

PubMed

Alberts, Bart B G T; de Brouwer, Anouk J; Selen, Luc P J; Medendorp, W Pieter

2016-01-01

Panoramic visual cues, as generated by the objects in the environment, provide the brain with important information about gravity direction. To derive an optimal, i.e., Bayesian, estimate of gravity direction, the brain must combine panoramic information with gravity information detected by the vestibular system. Here, we examined the individual sensory contributions to this estimate psychometrically. We asked human subjects to judge the orientation (clockwise or counterclockwise relative to gravity) of a briefly flashed luminous rod, presented within an oriented square frame (rod-in-frame). Vestibular contributions were manipulated by tilting the subject's head, whereas visual contributions were manipulated by changing the viewing distance of the rod and frame. Results show a cyclical modulation of the frame-induced bias in perceived verticality across a 90° range of frame orientations. The magnitude of this bias decreased significantly with larger viewing distance, as if visual reliability was reduced. Biases increased significantly when the head was tilted, as if vestibular reliability was reduced. A Bayesian optimal integration model, with distinct vertical and horizontal panoramic weights, a gain factor to allow for visual reliability changes, and ocular counterroll in response to head tilt, provided a good fit to the data. We conclude that subjects flexibly weigh visual panoramic and vestibular information based on their orientation-dependent reliability, resulting in the observed verticality biases and the associated response variabilities.

Pattern-histogram-based temporal change detection using personal chest radiographs

NASA Astrophysics Data System (ADS)

Ugurlu, Yucel; Obi, Takashi; Hasegawa, Akira; Yamaguchi, Masahiro; Ohyama, Nagaaki

1999-05-01

An accurate and reliable detection of temporal changes from a pair of images has considerable interest in the medical science. Traditional registration and subtraction techniques can be applied to extract temporal differences when,the object is rigid or corresponding points are obvious. However, in radiological imaging, loss of the depth information, the elasticity of object, the absence of clearly defined landmarks and three-dimensional positioning differences constraint the performance of conventional registration techniques. In this paper, we propose a new method in order to detect interval changes accurately without using an image registration technique. The method is based on construction of so-called pattern histogram and comparison procedure. The pattern histogram is a graphic representation of the frequency counts of all allowable patterns in the multi-dimensional pattern vector space. K-means algorithm is employed to partition pattern vector space successively. Any differences in the pattern histograms imply that different patterns are involved in the scenes. In our experiment, a pair of chest radiographs of pneumoconiosis is employed and the changing histogram bins are visualized on both of the images. We found that the method can be used as an alternative way of temporal change detection, particularly when the precise image registration is not available.

Molecular Thermometry

PubMed Central

McCabe, Kevin M.; Hernandez, Mark

2010-01-01

Conventional temperature measurements rely on material responses to heat, which can be detected visually. When Galileo developed an air expansion based device to detect temperature changes, Santorio, a contemporary physician, added a scale to create the first thermometer. With this instrument, patients’ temperatures could be measured, recorded and related to changing health conditions. Today, advances in materials science and bioengineering provide new ways to report temperature at the molecular level in real time. In this review the scientific foundations and history of thermometry underpin a discussion of the discoveries emerging from the field of molecular thermometry. Intracellular nanogels and heat sensing biomolecules have been shown to accurately report temperature changes at the nano-scale. Various systems will soon provide the ability to accurately measure temperature changes at the tissue, cellular, and even sub-cellular level, allowing for detection and monitoring of very small changes in local temperature. In the clinic this will lead to enhanced detection of tumors and localized infection, and accurate and precise monitoring of hyperthermia based therapies. Some nanomaterial systems have even demonstrated a theranostic capacity for heat-sensitive, local delivery of chemotherapeutics. Just as early thermometry moved into the clinic, so too will these molecular thermometers. PMID:20139796

Automatic video shot boundary detection using k-means clustering and improved adaptive dual threshold comparison

NASA Astrophysics Data System (ADS)

Sa, Qila; Wang, Zhihui

2018-03-01

At present, content-based video retrieval (CBVR) is the most mainstream video retrieval method, using the video features of its own to perform automatic identification and retrieval. This method involves a key technology, i.e. shot segmentation. In this paper, the method of automatic video shot boundary detection with K-means clustering and improved adaptive dual threshold comparison is proposed. First, extract the visual features of every frame and divide them into two categories using K-means clustering algorithm, namely, one with significant change and one with no significant change. Then, as to the classification results, utilize the improved adaptive dual threshold comparison method to determine the abrupt as well as gradual shot boundaries.Finally, achieve automatic video shot boundary detection system.

Evaluating the performance of the quick CSF method in detecting contrast sensitivity function changes

PubMed Central

Hou, Fang; Lesmes, Luis Andres; Kim, Woojae; Gu, Hairong; Pitt, Mark A.; Myung, Jay I.; Lu, Zhong-Lin

2016-01-01

The contrast sensitivity function (CSF) has shown promise as a functional vision endpoint for monitoring the changes in functional vision that accompany eye disease or its treatment. However, detecting CSF changes with precision and efficiency at both the individual and group levels is very challenging. By exploiting the Bayesian foundation of the quick CSF method (Lesmes, Lu, Baek, & Albright, 2010), we developed and evaluated metrics for detecting CSF changes at both the individual and group levels. A 10-letter identification task was used to assess the systematic changes in the CSF measured in three luminance conditions in 112 naïve normal observers. The data from the large sample allowed us to estimate the test–retest reliability of the quick CSF procedure and evaluate its performance in detecting CSF changes at both the individual and group levels. The test–retest reliability reached 0.974 with 50 trials. In 50 trials, the quick CSF method can detect a medium 0.30 log unit area under log CSF change with 94.0% accuracy at the individual observer level. At the group level, a power analysis based on the empirical distribution of CSF changes from the large sample showed that a very small area under log CSF change (0.025 log unit) could be detected by the quick CSF method with 112 observers and 50 trials. These results make it plausible to apply the method to monitor the progression of visual diseases or treatment effects on individual patients and greatly reduce the time, sample size, and costs in clinical trials at the group level. PMID:27120074

Detection of small orientation changes and the precision of visual working memory.

PubMed

Salmela, Viljami R; Saarinen, Jussi

2013-01-14

We investigated the precision of orientation representations with two tasks, change detection and recall. Previously change detection has been measured only with relatively large orientation changes compared to psychophysical thresholds. In the first experiment, we measured the observers' ability (d') to detect small changes in orientation (5-30°) with 1-4 Gabor items. With one item even a 10° change was well detected (average d'=2.5). As the amount of change increased to 30°, the d' increased to 5.2. When the number of items was increased, the d's gradually decreased. In the second experiment, we used a recall task and the observers adjusted the orientation of a probe Gabor to match the orientation of a Gabor held in the memory. The standard deviation (s.d.) of errors was calculated from the Gaussian distribution fitted to the data. As the number of items increased from 1 to 6, the s.d. increased from 8.6° to 19.6°. Even with six items, the observers did not make any random adjustments. The results show a square root relation between the d'/s.d. and the number of items. The d' in change detection is directly proportional to the square root of (1/n) and the orientation change. The increase of the s.d. in recall task is inversely proportional to square root of (1/n). The results suggest that limited resources and precision of representations, without additional assumptions, determine the memory performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

Longitudinal Detection of Optic Nerve Head Changes by Spectral Domain Optical Coherence Tomography in Early Experimental Glaucoma

PubMed Central

He, Lin; Yang, Hongli; Gardiner, Stuart K.; Williams, Galen; Hardin, Christy; Strouthidis, Nicholas G.; Fortune, Brad; Burgoyne, Claude F.

2014-01-01

Purpose. We determined if the detection of spectral-domain optical coherence tomography (SDOCT) optic nerve head (ONH) change precedes the detection of confocal scanning laser tomography (CSLT) ONH surface, SDOCT retinal nerve fiber layer (RNFL), scanning laser perimetry (SLP), and multifocal electroretinography (mfERG) change in eight experimental glaucoma (EG) eyes. Methods. Both eyes from eight monkeys were tested at least three times at baseline, and then every 2 weeks following laser-induced chronic unilateral IOP elevation. Event and trend-based definitions of onset in the control and EG eyes for 11 SDOCT neural and connective tissue, CSLT surface, SDOCT RNFL, SLP, and mfERG parameters were explored. The frequency and timing of onset for each parameter were compared using a logrank test. Results. Maximum post-laser IOP was 18 to 42 mm Hg in the EG eyes and 12 to 20 mm Hg in the control eyes. For event- and trend-based analyses, onsets were achieved earliest and most frequently within the ONH neural and connective tissues using SDOCT, and at the ONH surface using CSLT. SDOCT ONH neural and connective tissue parameter change preceded or coincided with CSLT ONH surface change in most EG eyes. The SDOCT and SLP measures of RNFL thickness, and mfERG measures of visual function demonstrated similar onset rates, but occurred later than SDOCT ONH and CSLT surface change, and in fewer eyes. Conclusions. SDOCT ONH change detection commonly precedes or coincides with CSLT ONH surface change detection, and consistently precedes RNFLT, SLP, and mfERG change detection in monkey experimental glaucoma. PMID:24255047

Metabolic alterations in patients with Parkinson disease and visual hallucinations.

PubMed

Boecker, Henning; Ceballos-Baumann, Andres O; Volk, Dominik; Conrad, Bastian; Forstl, Hans; Haussermann, Peter

2007-07-01

Visual hallucinations (VHs) occur frequently in advanced stages of Parkinson disease (PD). Which brain regions are affected in PD with VH is not well understood. To characterize the pattern of affected brain regions in PD with VH and to determine whether functional changes in PD with VH occur preferentially in visual association areas, as is suggested by the complex clinical symptomatology. Positron emission tomography measurements using fluorodeoxyglucose F 18. Between-group statistical analysis, accounting for the variance related to disease stage. University hospital. Patients Eight patients with PD and VH and 11 patients with PD without VH were analyzed. The presence of VH during the month before positron emission tomography was rated using the Neuropsychiatric Inventory subscale for VH (PD and VH, 4.63; PD without VH, 0.00; P < .002). Parkinson disease with VH, compared with PD without VH, was characterized by reduction in the regional cerebral metabolic rate for glucose consumption (P < .05, corrected for false discovery rate) in occipitotemporoparietal regions, sparing the occipital pole. No significant increase in regional glucose metabolism was detected in patients with PD and VH. The pattern of resting-state metabolic changes in regions of the dorsal and ventral visual streams, but not in primary visual cortex, in patients with PD and VH, is compatible with the functional roles of visual association areas in higher-order visual processing. These findings may help to further elucidate the functional mechanisms underlying VH in PD.

Altered visual perception in long-term ecstasy (MDMA) users.

PubMed

White, Claire; Brown, John; Edwards, Mark

2013-09-01

The present study investigated the long-term consequences of ecstasy use on visual processes thought to reflect serotonergic functions in the occipital lobe. Evidence indicates that the main psychoactive ingredient in ecstasy (methylendioxymethamphetamine) causes long-term changes to the serotonin system in human users. Previous research has found that amphetamine-abstinent ecstasy users have disrupted visual processing in the occipital lobe which relies on serotonin, with researchers concluding that ecstasy broadens orientation tuning bandwidths. However, other processes may have accounted for these results. The aim of the present research was to determine if amphetamine-abstinent ecstasy users have changes in occipital lobe functioning, as revealed by two studies: a masking study that directly measured the width of orientation tuning bandwidths and a contour integration task that measured the strength of long-range connections in the visual cortex of drug users compared to controls. Participants were compared on the width of orientation tuning bandwidths (26 controls, 12 ecstasy users, 10 ecstasy + amphetamine users) and the strength of long-range connections (38 controls, 15 ecstasy user, 12 ecstasy + amphetamine users) in the occipital lobe. Amphetamine-abstinent ecstasy users had significantly broader orientation tuning bandwidths than controls and significantly lower contour detection thresholds (CDTs), indicating worse performance on the task, than both controls and ecstasy + amphetamine users. These results extend on previous research, which is consistent with the proposal that ecstasy may damage the serotonin system, resulting in behavioral changes on tests of visual perception processes which are thought to reflect serotonergic functions in the occipital lobe.

Scene and human face recognition in the central vision of patients with glaucoma

PubMed Central

Aptel, Florent; Attye, Arnaud; Guyader, Nathalie; Boucart, Muriel; Chiquet, Christophe; Peyrin, Carole

2018-01-01

Primary open-angle glaucoma (POAG) firstly mainly affects peripheral vision. Current behavioral studies support the idea that visual defects of patients with POAG extend into parts of the central visual field classified as normal by static automated perimetry analysis. This is particularly true for visual tasks involving processes of a higher level than mere detection. The purpose of this study was to assess visual abilities of POAG patients in central vision. Patients were assigned to two groups following a visual field examination (Humphrey 24–2 SITA-Standard test). Patients with both peripheral and central defects and patients with peripheral but no central defect, as well as age-matched controls, participated in the experiment. All participants had to perform two visual tasks where low-contrast stimuli were presented in the central 6° of the visual field. A categorization task of scene images and human face images assessed high-level visual recognition abilities. In contrast, a detection task using the same stimuli assessed low-level visual function. The difference in performance between detection and categorization revealed the cost of high-level visual processing. Compared to controls, patients with a central visual defect showed a deficit in both detection and categorization of all low-contrast images. This is consistent with the abnormal retinal sensitivity as assessed by perimetry. However, the deficit was greater for categorization than detection. Patients without a central defect showed similar performances to the controls concerning the detection and categorization of faces. However, while the detection of scene images was well-maintained, these patients showed a deficit in their categorization. This suggests that the simple loss of peripheral vision could be detrimental to scene recognition, even when the information is displayed in central vision. This study revealed subtle defects in the central visual field of POAG patients that cannot be predicted by static automated perimetry assessment using Humphrey 24–2 SITA-Standard test. PMID:29481572

The internal model: A study of the relative contribution of proprioception and visual information to failure detection in dynamic systems. [sensitivity of operators versus monitors to failures

NASA Technical Reports Server (NTRS)

Kessel, C.; Wickens, C. D.

1978-01-01

The development of the internal model as it pertains to the detection of step changes in the order of control dynamics is investigated for two modes of participation: whether the subjects are actively controlling those dynamics or are monitoring an autopilot controlling them. A transfer of training design was used to evaluate the relative contribution of proprioception and visual information to the overall accuracy of the internal model. Sixteen subjects either tracked or monitored the system dynamics as a 2-dimensional pursuit display under single task conditions and concurrently with a sub-critical tracking task at two difficulty levels. Detection performance was faster and more accurate in the manual as opposed to the autopilot mode. The concurrent tracking task produced a decrement in detection performance for all conditions though this was more marked for the manual mode. The development of an internal model in the manual mode transferred positively to the automatic mode producing enhanced detection performance. There was no transfer from the internal model developed in the automatic mode to the manual mode.

Multifocal electroretinography in patients with Stargardt's macular dystrophy

PubMed Central

Kretschmann, U; Seeliger, M; Ruether, K; Usui, T; Apfelstedt-Sylla, E; Zrenner, E

1998-01-01

AIMS—To describe the topography of multifocal electroretinograms (ERGs) and to explore its diagnostic value in patients with Stargardt's macular dystrophy (SMD).
METHODS—51 patients with SMD were examined by means of the m-sequence technique to characterise the topography of electroretinographic responses in the central visual field. The results were compared with data from 30 normal volunteers.
RESULTS—In 49 of 51 patients with SMD, macular electroretinographic activity was markedly diminished or non-detectable. Towards more peripheral areas, ERG responses of the SMD patients approached those of normals. Implicit times were not markedly delayed at any eccentricity.
CONCLUSION—In contrast with Ganzfeld electroretinography, multifocal electroretinography is useful to detect foveal dysfunction in SMD. Areas of dysfunction were found to be usually larger than expected from psychophysical measurements and morphological alteration. In early stages of the disease it was possible to detect foveal dysfunction, even in patients lacking morphological fundus changes and with good visual acuity.

 Keywords: Stargardt's macular dystrophy; fundus flavimaculatus; electroretinography PMID:9602623

Risk and safety perception on urban and rural roads: Effects of environmental features, driver age and risk sensitivity.

PubMed

Cox, Jolene A; Beanland, Vanessa; Filtness, Ashleigh J

2017-10-03

The ability to detect changing visual information is a vital component of safe driving. In addition to detecting changing visual information, drivers must also interpret its relevance to safety. Environmental changes considered to have high safety relevance will likely demand greater attention and more timely responses than those considered to have lower safety relevance. The aim of this study was to explore factors that are likely to influence perceptions of risk and safety regarding changing visual information in the driving environment. Factors explored were the environment in which the change occurs (i.e., urban vs. rural), the type of object that changes, and the driver's age, experience, and risk sensitivity. Sixty-three licensed drivers aged 18-70 years completed a hazard rating task, which required them to rate the perceived hazardousness of changing specific elements within urban and rural driving environments. Three attributes of potential hazards were systematically manipulated: the environment (urban, rural); the type of object changed (road sign, car, motorcycle, pedestrian, traffic light, animal, tree); and its inherent safety risk (low risk, high risk). Inherent safety risk was manipulated by either varying the object's placement, on/near or away from the road, or altering an infrastructure element that would require a change to driver behavior. Participants also completed two driving-related risk perception tasks, rating their relative crash risk and perceived risk of aberrant driving behaviors. Driver age was not significantly associated with hazard ratings, but individual differences in perceived risk of aberrant driving behaviors predicted hazard ratings, suggesting that general driving-related risk sensitivity plays a strong role in safety perception. In both urban and rural scenes, there were significant associations between hazard ratings and inherent safety risk, with low-risk changes perceived as consistently less hazardous than high-risk impact changes; however, the effect was larger for urban environments. There were also effects of object type, with certain objects rated as consistently more safety relevant. In urban scenes, changes involving pedestrians were rated significantly more hazardous than all other objects, and in rural scenes, changes involving animals were rated as significantly more hazardous. Notably, hazard ratings were found to be higher in urban compared with rural driving environments, even when changes were matched between environments. This study demonstrates that drivers perceive rural roads as less risky than urban roads, even when similar scenarios occur in both environments. Age did not affect hazard ratings. Instead, the findings suggest that the assessment of risk posed by hazards is influenced more by individual differences in risk sensitivity. This highlights the need for driver education to account for appraisal of hazards' risk and relevance, in addition to hazard detection, when considering factors that promote road safety.

Processes to Preserve Spice and Herb Quality and Sensory Integrity During Pathogen Inactivation

PubMed Central

Moberg, Kayla; Amin, Kemia N.; Wright, Melissa; Newkirk, Jordan J.; Ponder, Monica A.; Acuff, Gary R.; Dickson, James S.

2017-01-01

Abstract Selected processing methods, demonstrated to be effective at reducing Salmonella, were assessed to determine if spice and herb quality was affected. Black peppercorn, cumin seed, oregano, and onion powder were irradiated to a target dose of 8 kGy. Two additional processes were examined for whole black peppercorns and cumin seeds: ethylene oxide (EtO) fumigation and vacuum assisted‐steam (82.22 °C, 7.5 psia). Treated and untreated spices/herbs were compared (visual, odor) using sensory similarity testing protocols (α = 0.20; β = 0.05; proportion of discriminators: 20%) to determine if processing altered sensory quality. Analytical assessment of quality (color, water activity, and volatile chemistry) was completed. Irradiation did not alter visual or odor sensory quality of black peppercorn, cumin seed, or oregano but created differences in onion powder, which was lighter (higher L *) and more red (higher a*) in color, and resulted in nearly complete loss of measured volatile compounds. EtO processing did not create detectable odor or appearance differences in black peppercorn; however visual and odor sensory quality differences, supported by changes in color (higher b *; lower L *) and increased concentrations of most volatiles, were detected for cumin seeds. Steam processing of black peppercorn resulted in perceptible odor differences, supported by increased concentration of monoterpene volatiles and loss of all sesquiterpenes; only visual differences were noted for cumin seed. An important step in process validation is the verification that no effect is detectable from a sensory perspective. PMID:28407236

Attention to Attributes and Objects in Working Memory

ERIC Educational Resources Information Center

Cowan, Nelson; Blume, Christopher L.; Saults, J. Scott

2013-01-01

It has been debated on the basis of change-detection procedures whether visual working memory is limited by the number of objects, task-relevant attributes within those objects, or bindings between attributes. This debate, however, has been hampered by several limitations, including the use of conditions that vary between studies and the absence…

Satellite Imagery Assisted Road-Based Visual Navigation System

NASA Astrophysics Data System (ADS)

Volkova, A.; Gibbens, P. W.

2016-06-01

There is a growing demand for unmanned aerial systems as autonomous surveillance, exploration and remote sensing solutions. Among the key concerns for robust operation of these systems is the need to reliably navigate the environment without reliance on global navigation satellite system (GNSS). This is of particular concern in Defence circles, but is also a major safety issue for commercial operations. In these circumstances, the aircraft needs to navigate relying only on information from on-board passive sensors such as digital cameras. An autonomous feature-based visual system presented in this work offers a novel integral approach to the modelling and registration of visual features that responds to the specific needs of the navigation system. It detects visual features from Google Earth* build a feature database. The same algorithm then detects features in an on-board cameras video stream. On one level this serves to localise the vehicle relative to the environment using Simultaneous Localisation and Mapping (SLAM). On a second level it correlates them with the database to localise the vehicle with respect to the inertial frame. The performance of the presented visual navigation system was compared using the satellite imagery from different years. Based on comparison results, an analysis of the effects of seasonal, structural and qualitative changes of the imagery source on the performance of the navigation algorithm is presented. * The algorithm is independent of the source of satellite imagery and another provider can be used

Task effects on BOLD signal correlates of implicit syntactic processing

PubMed Central

Caplan, David

2010-01-01

BOLD signal was measured in sixteen participants who made timed font change detection judgments in visually presented sentences that varied in syntactic structure and the order of animate and inanimate nouns. Behavioral data indicated that sentences were processed to the level of syntactic structure. BOLD signal increased in visual association areas bilaterally and left supramarginal gyrus in the contrast of sentences with object- and subject-extracted relative clauses without font changes in which the animacy order of the nouns biased against the syntactically determined meaning of the sentence. This result differs from the findings in a non-word detection task (Caplan et al, 2008a), in which the same contrast led to increased BOLD signal in the left inferior frontal gyrus. The difference in areas of activation indicates that the sentences were processed differently in the two tasks. These differences were further explored in an eye tracking study using the materials in the two tasks. Issues pertaining to how parsing and interpretive operations are affected by a task that is being performed, and how this might affect BOLD signal correlates of syntactic contrasts, are discussed. PMID:20671983

Task effects on BOLD signal correlates of implicit syntactic processing.

PubMed

Caplan, David

2010-07-01

BOLD signal was measured in sixteen participants who made timed font change detection judgments in visually presented sentences that varied in syntactic structure and the order of animate and inanimate nouns. Behavioral data indicated that sentences were processed to the level of syntactic structure. BOLD signal increased in visual association areas bilaterally and left supramarginal gyrus in the contrast of sentences with object- and subject-extracted relative clauses without font changes in which the animacy order of the nouns biased against the syntactically determined meaning of the sentence. This result differs from the findings in a non-word detection task (Caplan et al, 2008a), in which the same contrast led to increased BOLD signal in the left inferior frontal gyrus. The difference in areas of activation indicates that the sentences were processed differently in the two tasks. These differences were further explored in an eye tracking study using the materials in the two tasks. Issues pertaining to how parsing and interpretive operations are affected by a task that is being performed, and how this might affect BOLD signal correlates of syntactic contrasts, are discussed.

Alternation blindness in the representation of binary sequences.

PubMed

Yu, Ru Qi; Osherson, Daniel; Zhao, Jiaying

2018-03-01

Binary information is prevalent in the environment and contains 2 distinct outcomes. Binary sequences consist of a mixture of alternation and repetition. Understanding how people perceive such sequences would contribute to a general theory of information processing. In this study, we examined how people process alternation and repetition in binary sequences. Across 4 paradigms involving estimation, working memory, change detection, and visual search, we found that the number of alternations is underestimated compared with repetitions (Experiment 1). Moreover, recall for binary sequences deteriorates as the sequence alternates more (Experiment 2). Changes in bits are also harder to detect as the sequence alternates more (Experiment 3). Finally, visual targets superimposed on bits of a binary sequence take longer to process as alternation increases (Experiment 4). Overall, our results indicate that compared with repetition, alternation in a binary sequence is less salient in the sense of requiring more attention for successful encoding. The current study thus reveals the cognitive constraints in the representation of alternation and provides a new explanation for the overalternation bias in randomness perception. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Image denoising based on noise detection

NASA Astrophysics Data System (ADS)

Jiang, Yuanxiang; Yuan, Rui; Sun, Yuqiu; Tian, Jinwen

2018-03-01

Because of the noise points in the images, any operation of denoising would change the original information of non-noise pixel. A noise detection algorithm based on fractional calculus was proposed to denoise in this paper. Convolution of the image was made to gain direction gradient masks firstly. Then, the mean gray was calculated to obtain the gradient detection maps. Logical product was made to acquire noise position image next. Comparisons in the visual effect and evaluation parameters after processing, the results of experiment showed that the denoising algorithms based on noise were better than that of traditional methods in both subjective and objective aspects.

Quantification of oxidation on the surface of a polymer through photography

NASA Astrophysics Data System (ADS)

Yáñez M., J.; Estrada M., A.

2009-09-01

Oxidation in polymeric materials and special polyurethane is manifested by a yellow color, highly visible in white soles for footwear, besides presenting changes in its properties. Its importance varies according to the application of the material for which it was created. The most common way to detect this process is through a visual color change on the surface. In the present proposal we present a technique using digital photography for quantifying the color change in the polymer. The analysis of the photography is realized by means of projective geometry, since, relates the plane of the object and the one of the image of the object. This allows determining the area of the studied object, and by means of a histogram, which is determined each time for to record the progress of oxidation on the surface of the material. We present results of visual analysis and its behavior through a mathematical model.

The galilean satellites and Jupiter: Voyager 2 imaging science results

USGS Publications Warehouse

Smith, B.A.; Soderblom, L.A.; Beebe, R.; Boyce, J.; Briggs, G.; Carr, M.; Collins, S.A.; Cook, A.F.; Danielson, G.E.; Davies, M.E.; Hunt, G.E.; Ingersoll, A.; Johnson, T.V.; Masursky, H.; McCauley, J.; Morrison, D.; Owen, Timothy W.; Sagan, C.; Shoemaker, E.M.; Strom, R.; Suomi, V.E.; Veverka, J.

1979-01-01

Voyager 2, during its encounter with the Jupiter system, provided images that both complement and supplement in important ways the Voyager 1 images. While many changes have been observed in Jupiter's visual appearance, few, yet significant, changes have been detected in the principal atmospheric currents. Jupiter's ring system is strongly forward scattering at visual wavelengths and consists of a narrow annulus of highest particle density, within which is a broader region in which the density is lower. On Io, changes are observed in eruptive activity, plume structure, and surface albedo patterns. Europa's surface retains little or no record of intense meteorite bombardment, but does reveal a complex and, as yet, little-understood system of overlapping bright and dark linear features. Ganymede is found to have at least one unit of heavily cratered terrain on a surface that otherwise suggests widespread tectonism. Except for two large ringed basins, Callisto's entire surface is heavily cratered. Copyright ?? 1979 AAAS.

Curcumin based chemosensor for selective detection of fluoride and cyanide anions in aqueous media.

PubMed

Ponnuvel, Kandasamy; Santhiya, Kuppusamy; Padmini, Vediappen

2016-11-30

The conjugate N,N-dimethyl curcumin analogue fluorophore dye 1 has been synthesized and its performance as a sensor was demonstrated. As a fluoride and cyanide sensor it enabled visual detection, and showed changes in UV-vis and fluorescence spectra in the presence of fluoride and cyanide ions in aqueous medium. The Job's plot indicated that the formation of a complex between dye-1 fluoride ions has a 1 : 1 stoichiometric ratio.

Oral-Fluid Thiol-Detection Test Identifies Underlying Active Periodontal Disease Not Detected by the Visual Awake Examination.

PubMed

Queck, Katherine E; Chapman, Angela; Herzog, Leslie J; Shell-Martin, Tamara; Burgess-Cassler, Anthony; McClure, George David

Periodontal disease in dogs is highly prevalent but can only be accurately diagnosed by performing an anesthetized oral examination with periodontal probing and dental radiography. In this study, 114 dogs had a visual awake examination of the oral cavity and were administered an oral-fluid thiol-detection test prior to undergoing a a full-mouth anesthetized oral examination and digital dental radiographs. The results show the visual awake examination underestimated the presence and severity of active periodontal disease. The thiol-detection test was superior to the visual awake examination at detecting the presence and severity of active periodontal disease and was an indicator of progression toward alveolar bone loss. The thiol-detection test detected active periodontal disease at early stages of development, before any visual cues were present, indicating the need for intervention to prevent periodontal bone loss. Early detection is important because without intervention, dogs with gingivitis (active periodontal disease) progress to irreversible periodontal bone loss (stage 2+). As suggested in the current AAHA guidelines, a thiol-detection test administered in conjunction with the visual awake examination during routine wellness examinations facilitates veterinarian-client communication and mitigates under-diagnosis of periodontal disease and underutilization of dental services. The thiol-detection test can be used to monitor the periodontal health status of the conscious patient during follow-up examinations based on disease severity.

Congenital Anophthalmia and Binocular Neonatal Enucleation Differently Affect the Proteome of Primary and Secondary Visual Cortices in Mice.

PubMed

Laramée, Marie-Eve; Smolders, Katrien; Hu, Tjing-Tjing; Bronchti, Gilles; Boire, Denis; Arckens, Lutgarde

2016-01-01

In blind individuals, visually deprived occipital areas are activated by non-visual stimuli. The extent of this cross-modal activation depends on the age at onset of blindness. Cross-modal inputs have access to several anatomical pathways to reactivate deprived visual areas. Ectopic cross-modal subcortical connections have been shown in anophthalmic animals but not in animals deprived of sight at a later age. Direct and indirect cross-modal cortical connections toward visual areas could also be involved, yet the number of neurons implicated is similar between blind mice and sighted controls. Changes at the axon terminal, dendritic spine or synaptic level are therefore expected upon loss of visual inputs. Here, the proteome of V1, V2M and V2L from P0-enucleated, anophthalmic and sighted mice, sharing a common genetic background (C57BL/6J x ZRDCT/An), was investigated by 2-D DIGE and Western analyses to identify molecular adaptations to enucleation and/or anophthalmia. Few proteins were differentially expressed in enucleated or anophthalmic mice in comparison to sighted mice. The loss of sight affected three pathways: metabolism, synaptic transmission and morphogenesis. Most changes were detected in V1, followed by V2M. Overall, cross-modal adaptations could be promoted in both models of early blindness but not through the exact same molecular strategy. A lower metabolic activity observed in visual areas of blind mice suggests that even if cross-modal inputs reactivate visual areas, they could remain suboptimally processed.

Congenital Anophthalmia and Binocular Neonatal Enucleation Differently Affect the Proteome of Primary and Secondary Visual Cortices in Mice

PubMed Central

Smolders, Katrien; Hu, Tjing-Tjing; Bronchti, Gilles; Boire, Denis; Arckens, Lutgarde

2016-01-01

In blind individuals, visually deprived occipital areas are activated by non-visual stimuli. The extent of this cross-modal activation depends on the age at onset of blindness. Cross-modal inputs have access to several anatomical pathways to reactivate deprived visual areas. Ectopic cross-modal subcortical connections have been shown in anophthalmic animals but not in animals deprived of sight at a later age. Direct and indirect cross-modal cortical connections toward visual areas could also be involved, yet the number of neurons implicated is similar between blind mice and sighted controls. Changes at the axon terminal, dendritic spine or synaptic level are therefore expected upon loss of visual inputs. Here, the proteome of V1, V2M and V2L from P0-enucleated, anophthalmic and sighted mice, sharing a common genetic background (C57BL/6J x ZRDCT/An), was investigated by 2-D DIGE and Western analyses to identify molecular adaptations to enucleation and/or anophthalmia. Few proteins were differentially expressed in enucleated or anophthalmic mice in comparison to sighted mice. The loss of sight affected three pathways: metabolism, synaptic transmission and morphogenesis. Most changes were detected in V1, followed by V2M. Overall, cross-modal adaptations could be promoted in both models of early blindness but not through the exact same molecular strategy. A lower metabolic activity observed in visual areas of blind mice suggests that even if cross-modal inputs reactivate visual areas, they could remain suboptimally processed. PMID:27410964

Automatic Detection of Changes on Mars Surface from High-Resolution Orbital Images

NASA Astrophysics Data System (ADS)

Sidiropoulos, Panagiotis; Muller, Jan-Peter

2017-04-01

Over the last 40 years Mars has been extensively mapped by several NASA and ESA orbital missions, generating a large image dataset comprised of approximately 500,000 high-resolution images (of <100m resolution). The overall area mapped from orbital imagery is approximately 6 times the overall surface of Mars [1]. The multi-temporal coverage of Martian surface allows a visual inspection of the surface to identify dynamic phenomena, i.e. surface features that change over time, such as slope streaks [2], recurring slope lineae [3], new impact craters [4], etc. However, visual inspection for change detection is a limited approach, since it requires extensive use of human resources, which is very difficult to achieve when dealing with a rapidly increasing volume of data. Although citizen science can be employed for training and verification it is unsuitable for planetwide systematic change detection. In this work, we introduce a novel approach in planetary image change detection, which involves a batch-mode automatic change detection pipeline that identifies regions that have changed. This is tested in anger, on tens of thousands of high-resolution images over the MC11 quadrangle [5], acquired by CTX, HRSC, THEMIS-VIS and MOC-NA instruments [1]. We will present results which indicate a substantial level of activity in this region of Mars, including instances of dynamic natural phenomena that haven't been cataloged in the planetary science literature before. We will demonstrate the potential and usefulness of such an automatic approach in planetary science change detection. Acknowledgments: The research leading to these results has received funding from the STFC "MSSL Consolidated Grant" ST/K000977/1 and partial support from the European Union's Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n° 607379. References: [1] P. Sidiropoulos and J. - P. Muller (2015) On the status of orbital high-resolution repeat imaging of Mars for the observation of dynamic surface processes. Planetary and Space Science, 117: 207-222. [2] O. Aharonson, et al. (2003) Slope streak formation and dust deposition rates on Mars. Journal of Geophysical Research: Planets, 108(E12):5138 [3] A. McEwen, et al. (2011) Seasonal flows on warm martian slopes. Science, 333 (6043): 740-743. [4] S. Byrne, et al. (2009) Distribution of mid-latitude ground ice on mars from new impact craters. Science, 325(5948):1674-1676. [5] K. Gwinner, et al (2016) The High Resolution Stereo Camera (HRSC) of Mars Express and its approach to science analysis and mapping for Mars and its satellites. Planetary and Space Science, 126: 93-138.

Visual Costs of the Inhomogeneity of Luminance and Contrast by Viewing LCD-TFT Screens Off-Axis.

PubMed

Ziefle, Martina; Groeger, Thomas; Sommer, Dietmar

2003-01-01

In this study the anisotropic characteristics of TFT-LCD (Thin-Film-Transistor-Liquid Crystal Display) screens were examined. Anisotropy occurs as the distribution of luminance and contrast changes over the screen surface due to different viewing angles. On the basis of detailed photometric measurements the detection performance in a visual reaction task was measured in different viewing conditions. Viewing angle (0 degrees, frontal view; 30 degrees, off-axis; 50 degrees, off-axis) as well as ambient lighting (a dark or illuminated room) were varied. Reaction times and accuracy of detection performance were recorded. Results showed TFT's anisotropy to be a crucial factor deteriorating performance. With an increasing viewing angle performance decreased. It is concluded that TFT's anisotropy is a limiting factor for overall suitability and usefulness of this new display technology.

Similar effects of feature-based attention on motion perception and pursuit eye movements at different levels of awareness

PubMed Central

Spering, Miriam; Carrasco, Marisa

2012-01-01

Feature-based attention enhances visual processing and improves perception, even for visual features that we are not aware of. Does feature-based attention also modulate motor behavior in response to visual information that does or does not reach awareness? Here we compare the effect of feature-based attention on motion perception and smooth pursuit eye movements in response to moving dichoptic plaids–stimuli composed of two orthogonally-drifting gratings, presented separately to each eye–in human observers. Monocular adaptation to one grating prior to the presentation of both gratings renders the adapted grating perceptually weaker than the unadapted grating and decreases the level of awareness. Feature-based attention was directed to either the adapted or the unadapted grating’s motion direction or to both (neutral condition). We show that observers were better in detecting a speed change in the attended than the unattended motion direction, indicating that they had successfully attended to one grating. Speed change detection was also better when the change occurred in the unadapted than the adapted grating, indicating that the adapted grating was perceptually weaker. In neutral conditions, perception and pursuit in response to plaid motion were dissociated: While perception followed one grating’s motion direction almost exclusively (component motion), the eyes tracked the average of both gratings (pattern motion). In attention conditions, perception and pursuit were shifted towards the attended component. These results suggest that attention affects perception and pursuit similarly even though only the former reflects awareness. The eyes can track an attended feature even if observers do not perceive it. PMID:22649238

Similar effects of feature-based attention on motion perception and pursuit eye movements at different levels of awareness.

PubMed

Spering, Miriam; Carrasco, Marisa

2012-05-30

Feature-based attention enhances visual processing and improves perception, even for visual features that we are not aware of. Does feature-based attention also modulate motor behavior in response to visual information that does or does not reach awareness? Here we compare the effect of feature-based attention on motion perception and smooth-pursuit eye movements in response to moving dichoptic plaids--stimuli composed of two orthogonally drifting gratings, presented separately to each eye--in human observers. Monocular adaptation to one grating before the presentation of both gratings renders the adapted grating perceptually weaker than the unadapted grating and decreases the level of awareness. Feature-based attention was directed to either the adapted or the unadapted grating's motion direction or to both (neutral condition). We show that observers were better at detecting a speed change in the attended than the unattended motion direction, indicating that they had successfully attended to one grating. Speed change detection was also better when the change occurred in the unadapted than the adapted grating, indicating that the adapted grating was perceptually weaker. In neutral conditions, perception and pursuit in response to plaid motion were dissociated: While perception followed one grating's motion direction almost exclusively (component motion), the eyes tracked the average of both gratings (pattern motion). In attention conditions, perception and pursuit were shifted toward the attended component. These results suggest that attention affects perception and pursuit similarly even though only the former reflects awareness. The eyes can track an attended feature even if observers do not perceive it.

Spatiotemporal Receptive Field Properties of a Looming-Sensitive Neuron in Solitarious and Gregarious Phases of the Desert Locust

PubMed Central

Harston, George W. J.; Kilburn-Toppin, Fleur; Matheson, Thomas; Burrows, Malcolm; Gabbiani, Fabrizio; Krapp, Holger G.

2010-01-01

Desert locusts (Schistocerca gregaria) can transform reversibly between the swarming gregarious phase and a solitarious phase, which avoids other locusts. This transformation entails dramatic changes in morphology, physiology, and behavior. We have used the lobula giant movement detector (LGMD) and its postsynaptic target, the descending contralateral movement detector (DCMD), which are visual interneurons that detect looming objects, to analyze how differences in the visual ecology of the two phases are served by altered neuronal function. Solitarious locusts had larger eyes and a greater degree of binocular overlap than those of gregarious locusts. The receptive field to looming stimuli had a large central region of nearly equal response spanning 120° × 60° in both phases. The DCMDs of gregarious locusts responded more strongly than solitarious locusts and had a small caudolateral focus of even further sensitivity. More peripherally, the response was reduced in both phases, particularly ventrally, with gregarious locusts showing greater proportional decrease. Gregarious locusts showed less habituation to repeated looming stimuli along the eye equator than did solitarious locusts. By contrast, in other parts of the receptive field the degree of habituation was similar in both phases. The receptive field organization to looming stimuli contrasts strongly with the receptive field organization of the same neurons to nonlooming local-motion stimuli, which show much more pronounced regional variation. The DCMDs of both gregarious and solitarious locusts are able to detect approaching objects from across a wide expanse of visual space, but phase-specific changes in the spatiotemporal receptive field are linked to lifestyle changes. PMID:19955292

Nanoparticle sensor for label free detection of swine DNA in mixed biological samples

NASA Astrophysics Data System (ADS)

Ali, M. E.; Hashim, U.; Mustafa, S.; Che Man, Y. B.; Yusop, M. H. M.; Bari, M. F.; Islam, Kh N.; Hasan, M. F.

2011-05-01

We used 40 ± 5 nm gold nanoparticles (GNPs) as colorimetric sensor to visually detect swine-specific conserved sequence and nucleotide mismatch in PCR-amplified and non-amplified mitochondrial DNA mixtures to authenticate species. Colloidal GNPs changed color from pinkish-red to gray-purple in 2 mM PBS. Visually observed results were clearly reflected by the dramatic reduction of surface plasmon resonance peak at 530 nm and the appearance of new features in the 620-800 nm regions in their absorption spectra. The particles were stabilized against salt-induced aggregation upon the adsorption of single-stranded DNA. The PCR products, without any additional processing, were hybridized with a 17-base probe prior to exposure to GNPs. At a critical annealing temperature (55 °C) that differentiated matched and mismatched base pairing, the probe was hybridized to pig PCR product and dehybridized from the deer product. The dehybridized probe stuck to GNPs to prevent them from salt-induced aggregation and retained their characteristic red color. Hybridization of a 27-nucleotide probe to swine mitochondrial DNA identified them in pork-venison, pork-shad and venison-shad binary admixtures, eliminating the need of PCR amplification. Thus the assay was applied to authenticate species both in PCR-amplified and non-amplified heterogeneous biological samples. The results were determined visually and validated by absorption spectroscopy. The entire assay (hybridization plus visual detection) was performed in less than 10 min. The LOD (for genomic DNA) of the assay was 6 µg ml - 1 swine DNA in mixed meat samples. We believe the assay can be applied for species assignment in food analysis, mismatch detection in genetic screening and homology studies between closely related species.

Dual lanthanide-doped complexes: the development of a time-resolved ratiometric fluorescent probe for anthrax biomarker and a paper-based visual sensor.

PubMed

Wang, Qi-Xian; Xue, Shi-Fan; Chen, Zi-Han; Ma, Shi-Hui; Zhang, Shengqiang; Shi, Guoyue; Zhang, Min

2017-08-15

In this work, a novel time-resolved ratiometric fluorescent probe based on dual lanthanide (Tb: terbium, and Eu: europium)-doped complexes (Tb/DPA@SiO 2 -Eu/GMP) has been designed for detecting anthrax biomarker (dipicolinic acid, DPA), a unique and major component of anthrax spores. In such complexes-based probe, Tb/DPA@SiO 2 can serve as a stable reference signal with green fluorescence and Eu/GMP act as a sensitive response signal with red fluorescence for ratiometric fluorescent sensing DPA. Additionally, the probe exhibits long fluorescence lifetime, which can significantly reduce the autofluorescence interferences from biological samples by using time-resolved fluorescence measurement. More significantly, a paper-based visual sensor for DPA has been devised by using filter paper embedded with Tb/DPA@SiO 2 -Eu/GMP, and we have proved its utility for fluorescent detection of DPA, in which only a handheld UV lamp is used. In the presence of DPA, the paper-based visual sensor, illuminated by a handheld UV lamp, would result in an obvious fluorescence color change from green to red, which can be easily observed with naked eyes. The paper-based visual sensor is stable, portable, disposable, cost-effective and easy-to-use. The feasibility of using a smartphone with easy-to-access color-scanning APP as the detection platform for quantitative scanometric assays has been also demonstrated by coupled with our proposed paper-based visual sensor. This work unveils an effective method for accurate, sensitive and selective monitoring anthrax biomarker with backgroud-free and self-calibrating properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Constituting fully integrated visual analysis system for Cu(II) on TiO₂/cellulose paper.

PubMed

Li, Shun-Xing; Lin, Xiaofeng; Zheng, Feng-Ying; Liang, Wenjie; Zhong, Yanxue; Cai, Jiabai

2014-07-15

As a cheap and abundant porous material, cellulose filter paper was used to immobilize nano-TiO2 and denoted as TiO2/cellulose paper (TCP). With high adsorption capacity for Cu(II) (more than 1.65 mg), TCP was used as an adsorbent, photocatalyst, and colorimetric sensor at the same time. Under the optimum adsorption conditions, i.e., pH 6.5 and 25 °C, the adsorption ratio of Cu(II) was higher than 96.1%. Humic substances from the matrix could be enriched onto TCP but the interference of their colors on colorimetric detection could be eliminated by the photodegradation. In the presence of hydroxylamine, neocuproine, as a selective indicator, was added onto TCP, and a visual color change from white to orange was generated. The concentration of Cu(II) was quantified by the color intensity images using image processing software. This fully integrated visual analysis system was successfully applied for the detection of Cu(II) in 10.0 L of drinking water and seawater with a preconcentration factor of 10(4). The log-linear calibration curve for Cu(II) was in the range of 0.5-50.0 μg L(-1) with a determination coefficient (R(2)) of 0.985 and its detection limit was 0.073 μg L(-1).

Visual short-term memory load reduces retinotopic cortex response to contrast.

PubMed

Konstantinou, Nikos; Bahrami, Bahador; Rees, Geraint; Lavie, Nilli

2012-11-01

Load Theory of attention suggests that high perceptual load in a task leads to reduced sensory visual cortex response to task-unrelated stimuli resulting in "load-induced blindness" [e.g., Lavie, N. Attention, distraction and cognitive control under load. Current Directions in Psychological Science, 19, 143-148, 2010; Lavie, N. Distracted and confused?: Selective attention under load. Trends in Cognitive Sciences, 9, 75-82, 2005]. Consideration of the findings that visual STM (VSTM) involves sensory recruitment [e.g., Pasternak, T., & Greenlee, M. Working memory in primate sensory systems. Nature Reviews Neuroscience, 6, 97-107, 2005] within Load Theory led us to a new hypothesis regarding the effects of VSTM load on visual processing. If VSTM load draws on sensory visual capacity, then similar to perceptual load, high VSTM load should also reduce visual cortex response to incoming stimuli leading to a failure to detect them. We tested this hypothesis with fMRI and behavioral measures of visual detection sensitivity. Participants detected the presence of a contrast increment during the maintenance delay in a VSTM task requiring maintenance of color and position. Increased VSTM load (manipulated by increased set size) led to reduced retinotopic visual cortex (V1-V3) responses to contrast as well as reduced detection sensitivity, as we predicted. Additional visual detection experiments established a clear tradeoff between the amount of information maintained in VSTM and detection sensitivity, while ruling out alternative accounts for the effects of VSTM load in terms of differential spatial allocation strategies or task difficulty. These findings extend Load Theory to demonstrate a new form of competitive interactions between early visual cortex processing and visual representations held in memory under load and provide a novel line of support for the sensory recruitment hypothesis of VSTM.

Reduction in Dynamic Visual Acuity Reveals Gaze Control Changes Following Spaceflight

NASA Technical Reports Server (NTRS)

Peters, Brian T.; Brady, Rachel A.; Miller, Chris; Lawrence, Emily L.; Mulavara Ajitkumar P.; Bloomberg, Jacob J.

2010-01-01

INTRODUCTION: Exposure to microgravity causes adaptive changes in eye-head coordination that can lead to altered gaze control. This could affect postflight visual acuity during head and body motion. The goal of this study was to characterize changes in dynamic visual acuity after long-duration spaceflight. METHODS: Dynamic Visual Acuity (DVA) data from 14 astro/cosmonauts were collected after long-duration (6 months) spaceflight. The difference in acuity between seated and walking conditions provided a metric of change in the subjects ability to maintain gaze fixation during self-motion. In each condition, a psychophysical threshold detection algorithm was used to display Landolt ring optotypes at a size that was near each subject s acuity threshold. Verbal responses regarding the orientation of the gap were recorded as the optotypes appeared sequentially on a computer display 4 meters away. During the walking trials, subjects walked at 6.4 km/h on a motorized treadmill. RESULTS: A decrement in mean postflight DVA was found, with mean values returning to baseline within 1 week. The population mean showed a consistent improvement in DVA performance, but it was accompanied by high variability. A closer examination of the individual subject s recovery curves revealed that many did not follow a pattern of continuous improvement with each passing day. When adjusted on the basis of previous long-duration flight experience, the population mean shows a "bounce" in the re-adaptation curve. CONCLUSION: Gaze control during self-motion is altered following long-duration spaceflight and changes in postflight DVA performance indicate that vestibular re-adaptation may be more complex than a gradual return to normal.

Fluorescence growth of self-polymerized fluorescence polydopamine for ratiometric visual detection of DA.

PubMed

Yu, Miao; Lu, Yang; Tan, Zhenjiang

2017-06-01

In this work, a novel and facile ratiometric fluorescence probe was prepared for the visual detection of dopamine (DA). In this detection system, red-emission CdTe@SiO 2 (r-QDs@SiO 2 ) was used as steady core of the probe and inverse microemulsion method was applied to synthesize uniform r-QDs@SiO 2 , this step could protect CdTe from contacting with human skin directly. Polydopamine (PDA) acted as response signal to detect DA, a very handy method which just combined polyethyleneimine (PEI) with DA together to synthesize PDA, this way for synthesis of PDA was much time-saving and non-toxic than any other methods. Differently from traditional analysis processes, the products of this experiment were also the analysis substances in final. Under optimum measurement conditions, the dual-emission ratiometric fluorescence probe was used for detections of DA in a concentration ranged from 10μM to 80μM with a detection limit of 0.12μM, with addition of DA the color of the probe changed from red to green watched by naked eyes. In addition, the developed probe was also used for detections of DA in human serum samples successfully. This study provides a simple, time-saving and non-toxic approach for detections of DA without the requirement of complex equipment. Copyright © 2017 Elsevier B.V. All rights reserved.

Broad attention to multiple individual objects may facilitate change detection with complex auditory scenes.

PubMed

Irsik, Vanessa C; Vanden Bosch der Nederlanden, Christina M; Snyder, Joel S

2016-11-01

Attention and other processing constraints limit the perception of objects in complex scenes, which has been studied extensively in the visual sense. We used a change deafness paradigm to examine how attention to particular objects helps and hurts the ability to notice changes within complex auditory scenes. In a counterbalanced design, we examined how cueing attention to particular objects affected performance in an auditory change-detection task through the use of valid or invalid cues and trials without cues (Experiment 1). We further examined how successful encoding predicted change-detection performance using an object-encoding task and we addressed whether performing the object-encoding task along with the change-detection task affected performance overall (Experiment 2). Participants had more error for invalid compared to valid and uncued trials, but this effect was reduced in Experiment 2 compared to Experiment 1. When the object-encoding task was present, listeners who completed the uncued condition first had less overall error than those who completed the cued condition first. All participants showed less change deafness when they successfully encoded change-relevant compared to irrelevant objects during valid and uncued trials. However, only participants who completed the uncued condition first also showed this effect during invalid cue trials, suggesting a broader scope of attention. These findings provide converging evidence that attention to change-relevant objects is crucial for successful detection of acoustic changes and that encouraging broad attention to multiple objects is the best way to reduce change deafness. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Crown-of-thorns starfish have true image forming vision.

PubMed

Petie, Ronald; Garm, Anders; Hall, Michael R

2016-01-01

Photoreceptors have evolved numerous times giving organisms the ability to detect light and respond to specific visual stimuli. Studies into the visual abilities of the Asteroidea (Echinodermata) have recently shown that species within this class have a more developed visual sense than previously thought and it has been demonstrated that starfish use visual information for orientation within their habitat. Whereas image forming eyes have been suggested for starfish, direct experimental proof of true spatial vision has not yet been obtained. The behavioural response of the coral reef inhabiting crown-of-thorns starfish (Acanthaster planci) was tested in controlled aquarium experiments using an array of stimuli to examine their visual performance. We presented starfish with various black-and-white shapes against a mid-intensity grey background, designed such that the animals would need to possess true spatial vision to detect these shapes. Starfish responded to black-and-white rectangles, but no directional response was found to black-and-white circles, despite equal areas of black and white. Additionally, we confirmed that starfish were attracted to black circles on a white background when the visual angle is larger than 14°. When changing the grey tone of the largest circle from black to white, we found responses to contrasts of 0.5 and up. The starfish were attracted to the dark area's of the visual stimuli and were found to be both attracted and repelled by the visual targets. For crown-of-thorns starfish, visual cues are essential for close range orientation towards objects, such as coral boulders, in the wild. These visually guided behaviours can be replicated in aquarium conditions. Our observation that crown-of-thorns starfish respond to black-and-white shapes on a mid-intensity grey background is the first direct proof of true spatial vision in starfish and in the phylum Echinodermata.

Active visual search in non-stationary scenes: coping with temporal variability and uncertainty

NASA Astrophysics Data System (ADS)

Ušćumlić, Marija; Blankertz, Benjamin

2016-02-01

Objective. State-of-the-art experiments for studying neural processes underlying visual cognition often constrain sensory inputs (e.g., static images) and our behavior (e.g., fixed eye-gaze, long eye fixations), isolating or simplifying the interaction of neural processes. Motivated by the non-stationarity of our natural visual environment, we investigated the electroencephalography (EEG) correlates of visual recognition while participants overtly performed visual search in non-stationary scenes. We hypothesized that visual effects (such as those typically used in human-computer interfaces) may increase temporal uncertainty (with reference to fixation onset) of cognition-related EEG activity in an active search task and therefore require novel techniques for single-trial detection. Approach. We addressed fixation-related EEG activity in an active search task with respect to stimulus-appearance styles and dynamics. Alongside popping-up stimuli, our experimental study embraces two composite appearance styles based on fading-in, enlarging, and motion effects. Additionally, we explored whether the knowledge obtained in the pop-up experimental setting can be exploited to boost the EEG-based intention-decoding performance when facing transitional changes of visual content. Main results. The results confirmed our initial hypothesis that the dynamic of visual content can increase temporal uncertainty of the cognition-related EEG activity in active search with respect to fixation onset. This temporal uncertainty challenges the pivotal aim to keep the decoding performance constant irrespective of visual effects. Importantly, the proposed approach for EEG decoding based on knowledge transfer between the different experimental settings gave a promising performance. Significance. Our study demonstrates that the non-stationarity of visual scenes is an important factor in the evolution of cognitive processes, as well as in the dynamic of ocular behavior (i.e., dwell time and fixation duration) in an active search task. In addition, our method to improve single-trial detection performance in this adverse scenario is an important step in making brain-computer interfacing technology available for human-computer interaction applications.

Biochemical, histological and behavioural aspects of visual function during early development of rainbow trout

USGS Publications Warehouse

Carvalho, Paulo S. M.; Noltie, Douglas B.; Tillitt, D.E.

2004-01-01

Retinal structure and concentration of retinoids involved in phototransduction changed during early development of rainbow trout Oncorhynchus mykiss, correlating with improvements in visual function. A test chamber was used to evaluate the presence of optokinetic or optomotor responses and to assess the functionality of the integrated cellular, physiological and biochemical components of the visual system. The results indicated that in rainbow trout optomotor responses start at 10 days post-hatch, and demonstrated for the first time that increases in acuity, sensitivity to low light as well as in motion detection abilities occur from this stage until exogenous feeding starts. The structure of retinal cells such as cone ellipsoids increased in length as photopic visual acuity improved, and rod densities increased concurrently with improvements in scotopic thresholds (2.2 log10 units). An increase in the concentrations of the chromophore all-trans-retinal correlated with improvements of all behavioural measures of visual function during the same developmental phase. ?? 2004 The Fisheries Society of the British Isles.

Salience of the lambs: a test of the saliency map hypothesis with pictures of emotive objects.

PubMed

Humphrey, Katherine; Underwood, Geoffrey; Lambert, Tony

2012-01-25

Humans have an ability to rapidly detect emotive stimuli. However, many emotional objects in a scene are also highly visually salient, which raises the question of how dependent the effects of emotionality are on visual saliency and whether the presence of an emotional object changes the power of a more visually salient object in attracting attention. Participants were shown a set of positive, negative, and neutral pictures and completed recall and recognition memory tests. Eye movement data revealed that visual saliency does influence eye movements, but the effect is reliably reduced when an emotional object is present. Pictures containing negative objects were recognized more accurately and recalled in greater detail, and participants fixated more on negative objects than positive or neutral ones. Initial fixations were more likely to be on emotional objects than more visually salient neutral ones, suggesting that the processing of emotional features occurs at a very early stage of perception.

Viewpoint Dependent Imaging: An Interactive Stereoscopic Display

NASA Astrophysics Data System (ADS)

Fisher, Scott

1983-04-01

Design and implementation of a viewpoint Dependent imaging system is described. The resultant display is an interactive, lifesize, stereoscopic image. that becomes a window into a three dimensional visual environment. As the user physically changes his viewpoint of the represented data in relation to the display surface, the image is continuously updated. The changing viewpoints are retrieved from a comprehensive, stereoscopic image array stored on computer controlled, optical videodisc and fluidly presented. in coordination with the viewer's, movements as detected by a body-tracking device. This imaging system is an attempt to more closely represent an observers interactive perceptual experience of the visual world by presenting sensory information cues not offered by traditional media technologies: binocular parallax, motion parallax, and motion perspective. Unlike holographic imaging, this display requires, relatively low bandwidth.

A Paper-Based Electrochromic Array for Visualized Electrochemical Sensing.

PubMed

Zhang, Fengling; Cai, Tianyi; Ma, Liang; Zhan, Liyuan; Liu, Hong

2017-01-31

We report a battery-powered, paper-based electrochromic array for visualized electrochemical sensing. The paper-based sensing system consists of six parallel electrochemical cells, which are powered by an aluminum-air battery. Each single electrochemical cell uses a Prussian Blue spot electrodeposited on an indium-doped tin oxide thin film as the electrochromic indicator. Each electrochemical cell is preloaded with increasing amounts of analyte. The sample activates the battery for the sensing. Both the preloaded analyte and the analyte in the sample initiate the color change of Prussian Blue to Prussian White. With a reaction time of 60 s, the number of electrochemical cells with complete color changes is correlated to the concentration of analyte in the sample. As a proof-of-concept analyte, lactic acid was detected semi-quantitatively using the naked eye.

A far-field-viewing sensor for making analytical measurements in remote locations.

PubMed

Michael, K L; Taylor, L C; Walt, D R

1999-07-15

We demonstrate a far-field-viewing GRINscope sensor for making analytical measurements in remote locations. The GRINscope was fabricated by permanently affixing a micro-Gradient index (GRIN) lens on the distal face of a 350-micron-diameter optical imaging fiber. The GRINscope can obtain both chemical and visual information. In one application, a thin, pH-sensitive polymer layer was immobilized on the distal end of the GRINscope. The ability of the GRINscope to visually image its far-field surroundings and concurrently detect pH changes in a flowing stream was demonstrated. In a different application, the GRINscope was used to image pH- and O2-sensitive particles on a remote substrate and simultaneously measure their fluorescence intensity in response to pH or pO2 changes.

Transcranial Random Noise Stimulation of Visual Cortex: Stochastic Resonance Enhances Central Mechanisms of Perception.

PubMed

van der Groen, Onno; Wenderoth, Nicole

2016-05-11

Random noise enhances the detectability of weak signals in nonlinear systems, a phenomenon known as stochastic resonance (SR). Though counterintuitive at first, SR has been demonstrated in a variety of naturally occurring processes, including human perception, where it has been shown that adding noise directly to weak visual, tactile, or auditory stimuli enhances detection performance. These results indicate that random noise can push subthreshold receptor potentials across the transfer threshold, causing action potentials in an otherwise silent afference. Despite the wealth of evidence demonstrating SR for noise added to a stimulus, relatively few studies have explored whether or not noise added directly to cortical networks enhances sensory detection. Here we administered transcranial random noise stimulation (tRNS; 100-640 Hz zero-mean Gaussian white noise) to the occipital region of human participants. For increasing tRNS intensities (ranging from 0 to 1.5 mA), the detection accuracy of a visual stimuli changed according to an inverted-U-shaped function, typical of the SR phenomenon. When the optimal level of noise was added to visual cortex, detection performance improved significantly relative to a zero noise condition (9.7 ± 4.6%) and to a similar extent as optimal noise added to the visual stimuli (11.2 ± 4.7%). Our results demonstrate that adding noise to cortical networks can improve human behavior and that tRNS is an appropriate tool to exploit this mechanism. Our findings suggest that neural processing at the network level exhibits nonlinear system properties that are sensitive to the stochastic resonance phenomenon and highlight the usefulness of tRNS as a tool to modulate human behavior. Since tRNS can be applied to all cortical areas, exploiting the SR phenomenon is not restricted to the perceptual domain, but can be used for other functions that depend on nonlinear neural dynamics (e.g., decision making, task switching, response inhibition, and many other processes). This will open new avenues for using tRNS to investigate brain function and enhance the behavior of healthy individuals or patients. Copyright © 2016 the authors 0270-6474/16/365289-10$15.00/0.

Featural and temporal attention selectively enhance task-appropriate representations in human V1

PubMed Central

Warren, Scott; Yacoub, Essa; Ghose, Geoffrey

2015-01-01

Our perceptions are often shaped by focusing our attention toward specific features or periods of time irrespective of location. We explore the physiological bases of these non-spatial forms of attention by imaging brain activity while subjects perform a challenging change detection task. The task employs a continuously varying visual stimulus that, for any moment in time, selectively activates functionally distinct subpopulations of primary visual cortex (V1) neurons. When subjects are cued to the timing and nature of the change, the mapping of orientation preference across V1 was systematically shifts toward the cued stimulus just prior to its appearance. A simple linear model can explain this shift: attentional changes are selectively targeted toward neural subpopulations representing the attended feature at the times the feature was anticipated. Our results suggest that featural attention is mediated by a linear change in the responses of task-appropriate neurons across cortex during appropriate periods of time. PMID:25501983

Visual analytics techniques for large multi-attribute time series data

NASA Astrophysics Data System (ADS)

Hao, Ming C.; Dayal, Umeshwar; Keim, Daniel A.

2008-01-01

Time series data commonly occur when variables are monitored over time. Many real-world applications involve the comparison of long time series across multiple variables (multi-attributes). Often business people want to compare this year's monthly sales with last year's sales to make decisions. Data warehouse administrators (DBAs) want to know their daily data loading job performance. DBAs need to detect the outliers early enough to act upon them. In this paper, two new visual analytic techniques are introduced: The color cell-based Visual Time Series Line Charts and Maps highlight significant changes over time in a long time series data and the new Visual Content Query facilitates finding the contents and histories of interesting patterns and anomalies, which leads to root cause identification. We have applied both methods to two real-world applications to mine enterprise data warehouse and customer credit card fraud data to illustrate the wide applicability and usefulness of these techniques.

Techniques for Fault Detection and Visualization of Telemetry Dependence Relationships for Root Cause Fault Analysis in Complex Systems

NASA Astrophysics Data System (ADS)

Guy, Nathaniel

This thesis explores new ways of looking at telemetry data, from a time-correlative perspective, in order to see patterns within the data that may suggest root causes of system faults. It was thought initially that visualizing an animated Pearson Correlation Coefficient (PCC) matrix for telemetry channels would be sufficient to give new understanding; however, testing showed that the high dimensionality and inability to easily look at change over time in this approach impeded understanding. Different correlative techniques, combined with the time curve visualization proposed by Bach et al (2015), were adapted to visualize both raw telemetry and telemetry data correlations. Review revealed that these new techniques give insights into the data, and an intuitive grasp of data families, which show the effectiveness of this approach for enhancing system understanding and assisting with root cause analysis for complex aerospace systems.

Cognitive Control Network Contributions to Memory-Guided Visual Attention

PubMed Central

Rosen, Maya L.; Stern, Chantal E.; Michalka, Samantha W.; Devaney, Kathryn J.; Somers, David C.

2016-01-01

Visual attentional capacity is severely limited, but humans excel in familiar visual contexts, in part because long-term memories guide efficient deployment of attention. To investigate the neural substrates that support memory-guided visual attention, we performed a set of functional MRI experiments that contrast long-term, memory-guided visuospatial attention with stimulus-guided visuospatial attention in a change detection task. Whereas the dorsal attention network was activated for both forms of attention, the cognitive control network (CCN) was preferentially activated during memory-guided attention. Three posterior nodes in the CCN, posterior precuneus, posterior callosal sulcus/mid-cingulate, and lateral intraparietal sulcus exhibited the greatest specificity for memory-guided attention. These 3 regions exhibit functional connectivity at rest, and we propose that they form a subnetwork within the broader CCN. Based on the task activation patterns, we conclude that the nodes of this subnetwork are preferentially recruited for long-term memory guidance of visuospatial attention. PMID:25750253

Accurate metacognition for visual sensory memory representations.

PubMed

Vandenbroucke, Annelinde R E; Sligte, Ilja G; Barrett, Adam B; Seth, Anil K; Fahrenfort, Johannes J; Lamme, Victor A F

2014-04-01

The capacity to attend to multiple objects in the visual field is limited. However, introspectively, people feel that they see the whole visual world at once. Some scholars suggest that this introspective feeling is based on short-lived sensory memory representations, whereas others argue that the feeling of seeing more than can be attended to is illusory. Here, we investigated this phenomenon by combining objective memory performance with subjective confidence ratings during a change-detection task. This allowed us to compute a measure of metacognition--the degree of knowledge that subjects have about the correctness of their decisions--for different stages of memory. We show that subjects store more objects in sensory memory than they can attend to but, at the same time, have similar metacognition for sensory memory and working memory representations. This suggests that these subjective impressions are not an illusion but accurate reflections of the richness of visual perception.

Olfactory lateralization in the chick.

PubMed

Vallortigara, G; Andrew, R J

1994-04-01

Chicks using their right nostril (and so with direct olfactory input to the right hemisphere), and presented simultaneously with two objects identical in visual appearance with the rearing object, and differing only in odour, chose that which smelled like the rearing object. Chicks using the left nostril chose equally readily but at random. Earlier work, using similar tests, has shown special interest of the right hemisphere in change in visual properties of familiar stimuli, suggesting that analysis of a wide range of properties of a familiar stimulus may be an important function of the right hemisphere in the chick, with consequent detection of novelty.

A fuzzy measure approach to motion frame analysis for scene detection. M.S. Thesis - Houston Univ.

NASA Technical Reports Server (NTRS)

Leigh, Albert B.; Pal, Sankar K.

1992-01-01

This paper addresses a solution to the problem of scene estimation of motion video data in the fuzzy set theoretic framework. Using fuzzy image feature extractors, a new algorithm is developed to compute the change of information in each of two successive frames to classify scenes. This classification process of raw input visual data can be used to establish structure for correlation. The algorithm attempts to fulfill the need for nonlinear, frame-accurate access to video data for applications such as video editing and visual document archival/retrieval systems in multimedia environments.

Auditory enhancement of visual perception at threshold depends on visual abilities.

PubMed

Caclin, Anne; Bouchet, Patrick; Djoulah, Farida; Pirat, Elodie; Pernier, Jacques; Giard, Marie-Hélène

2011-06-17

Whether or not multisensory interactions can improve detection thresholds, and thus widen the range of perceptible events is a long-standing debate. Here we revisit this question, by testing the influence of auditory stimuli on visual detection threshold, in subjects exhibiting a wide range of visual-only performance. Above the perceptual threshold, crossmodal interactions have indeed been reported to depend on the subject's performance when the modalities are presented in isolation. We thus tested normal-seeing subjects and short-sighted subjects wearing their usual glasses. We used a paradigm limiting potential shortcomings of previous studies: we chose a criterion-free threshold measurement procedure and precluded exogenous cueing effects by systematically presenting a visual cue whenever a visual target (a faint Gabor patch) might occur. Using this carefully controlled procedure, we found that concurrent sounds only improved visual detection thresholds in the sub-group of subjects exhibiting the poorest performance in the visual-only conditions. In these subjects, for oblique orientations of the visual stimuli (but not for vertical or horizontal targets), the auditory improvement was still present when visual detection was already helped with flanking visual stimuli generating a collinear facilitation effect. These findings highlight that crossmodal interactions are most efficient to improve perceptual performance when an isolated modality is deficient. Copyright © 2011 Elsevier B.V. All rights reserved.

Electrophysiological evidence for parallel and serial processing during visual search.

PubMed

Luck, S J; Hillyard, S A

1990-12-01

Event-related potentials were recorded from young adults during a visual search task in order to evaluate parallel and serial models of visual processing in the context of Treisman's feature integration theory. Parallel and serial search strategies were produced by the use of feature-present and feature-absent targets, respectively. In the feature-absent condition, the slopes of the functions relating reaction time and latency of the P3 component to set size were essentially identical, indicating that the longer reaction times observed for larger set sizes can be accounted for solely by changes in stimulus identification and classification time, rather than changes in post-perceptual processing stages. In addition, the amplitude of the P3 wave on target-present trials in this condition increased with set size and was greater when the preceding trial contained a target, whereas P3 activity was minimal on target-absent trials. These effects are consistent with the serial self-terminating search model and appear to contradict parallel processing accounts of attention-demanding visual search performance, at least for a subset of search paradigms. Differences in ERP scalp distributions further suggested that different physiological processes are utilized for the detection of feature presence and absence.

Prestimulus neural oscillations inhibit visual perception via modulation of response gain.

PubMed

Chaumon, Maximilien; Busch, Niko A

2014-11-01

The ongoing state of the brain radically affects how it processes sensory information. How does this ongoing brain activity interact with the processing of external stimuli? Spontaneous oscillations in the alpha range are thought to inhibit sensory processing, but little is known about the psychophysical mechanisms of this inhibition. We recorded ongoing brain activity with EEG while human observers performed a visual detection task with stimuli of different contrast intensities. To move beyond qualitative description, we formally compared psychometric functions obtained under different levels of ongoing alpha power and evaluated the inhibitory effect of ongoing alpha oscillations in terms of contrast or response gain models. This procedure opens the way to understanding the actual functional mechanisms by which ongoing brain activity affects visual performance. We found that strong prestimulus occipital alpha oscillations-but not more anterior mu oscillations-reduce performance most strongly for stimuli of the highest intensities tested. This inhibitory effect is best explained by a divisive reduction of response gain. Ongoing occipital alpha oscillations thus reflect changes in the visual system's input/output transformation that are independent of the sensory input to the system. They selectively scale the system's response, rather than change its sensitivity to sensory information.

CDS Re Mix

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

CDS (Change Detection Systems) is a mechanism for rapid visual analysis using complex image alignment algorithms. CDS is controlled with a simple interface that has been designed for use for anyone that can operate a digital camera. A challenge of complex industrial systems like nuclear power plants is to accurately identify changes in systems, structures and components that may critically impact the operation of the facility. CDS can provide a means of early intervention before the issues evolve into safety and production challenges.

Operating principles and detection characteristics of the Visible and Near-Infrared Imaging Spectrometer in the Chang'e-3

NASA Astrophysics Data System (ADS)

He, Zhi-Ping; Wang, Bin-Yong; Lü, Gang; Li, Chun-Lai; Yuan, Li-Yin; Xu, Rui; Liu, Bin; Chen, Kai; Wang, Jian-Yu

2014-12-01

The Visible and Near-Infrared Imaging Spectrometer (VNIS), using two acousto-optic tunable filters as dispersive components, consists of a VIS/NIR imaging spectrometer (0.45-0.95 μm), a shortwave IR spectrometer (0.9-2.4 μm) and a calibration unit with dust-proofing functionality. The VNIS was utilized to detect the spectrum of the lunar surface and achieve in-orbit calibration, which satisfied the requirements for scientific detection. Mounted at the front of the Yutu rover, lunar objects that are detected with the VNIS with a 45° visual angle to obtain spectra and geometrical data in order to analyze the mineral composition of the lunar surface. After landing successfully on the Moon, the VNIS performed several explorations and calibrations, and obtained several spectral images and spectral reflectance curves of the lunar soil in the region of Mare Imbrium. This paper describes the working principle and detection characteristics of the VNIS and provides a reference for data processing and scientific applications.

Visual field progression in glaucoma: total versus pattern deviation analyses.

PubMed

Artes, Paul H; Nicolela, Marcelo T; LeBlanc, Raymond P; Chauhan, Balwantray C

2005-12-01

To compare visual field progression with total and pattern deviation analyses in a prospective longitudinal study of patients with glaucoma and healthy control subjects. A group of 101 patients with glaucoma (168 eyes) with early to moderately advanced visual field loss at baseline (average mean deviation [MD], -3.9 dB) and no clinical evidence of media opacity were selected from a prospective longitudinal study on visual field progression in glaucoma. Patients were examined with static automated perimetry at 6-month intervals for a median follow-up of 9 years. At each test location, change was established with event and trend analyses of total and pattern deviation. The event analyses compared each follow-up test to a baseline obtained from averaging the first two tests, and visual field progression was defined as deterioration beyond the 5th percentile of test-retest variability at three test locations, observed on three consecutive tests. The trend analyses were based on point-wise linear regression, and visual field progression was defined as statistically significant deterioration (P < 5%) worse than -1 dB/year at three locations, confirmed by independently omitting the last and the penultimate observation. The incidence and the time-to-progression were compared between total and pattern deviation analyses. To estimate the specificity of the progression analyses, identical criteria were applied to visual fields obtained in 102 healthy control subjects, and the rate of visual field improvement was established in the patients with glaucoma and the healthy control subjects. With both event and trend methods, pattern deviation analyses classified approximately 15% fewer eyes as having progressed than did the total deviation analyses. In eyes classified as progressing by both the total and pattern deviation methods, total deviation analyses tended to detect progression earlier than the pattern deviation analyses. A comparison of the changes observed in MD and the visual fields' general height (estimated by the 85th percentile of the total deviation values) confirmed that change in the glaucomatous eyes almost always comprised a diffuse component. Pattern deviation analyses of progression may therefore underestimate the true amount of glaucomatous visual field progression. Pattern deviation analyses of visual field progression may underestimate visual field progression in glaucoma, particularly when there is no clinical evidence of increasing media opacity. Clinicians should have access to both total and pattern deviation analyses to make informed decisions on visual field progression in glaucoma.

Detection of emotional faces: salient physical features guide effective visual search.

PubMed

Calvo, Manuel G; Nummenmaa, Lauri

2008-08-01

In this study, the authors investigated how salient visual features capture attention and facilitate detection of emotional facial expressions. In a visual search task, a target emotional face (happy, disgusted, fearful, angry, sad, or surprised) was presented in an array of neutral faces. Faster detection of happy and, to a lesser extent, surprised and disgusted faces was found both under upright and inverted display conditions. Inversion slowed down the detection of these faces less than that of others (fearful, angry, and sad). Accordingly, the detection advantage involves processing of featural rather than configural information. The facial features responsible for the detection advantage are located in the mouth rather than the eye region. Computationally modeled visual saliency predicted both attentional orienting and detection. Saliency was greatest for the faces (happy) and regions (mouth) that were fixated earlier and detected faster, and there was close correspondence between the onset of the modeled saliency peak and the time at which observers initially fixated the faces. The authors conclude that visual saliency of specific facial features--especially the smiling mouth--is responsible for facilitated initial orienting, which thus shortens detection. (PsycINFO Database Record (c) 2008 APA, all rights reserved).

Heidelberg edge perimeter employment in glaucoma diagnosis--preliminary report.

PubMed

Mulak, Małgorzata; Szumny, Dorota; Sieja-Bujewska, Anna; Kubrak, Magdalena

2012-01-01

In recent years, the authors have seen huge progress in the diagnosis of eye diseases. One of the new diagnostic devices is HEP (Heidelberg Edge Perimeter) - for early diagnosis of glaucoma and its progression. It combines visual field test and HRT (Heidelberg Retina Tomograph), which allows authors to obtain the image of the mutual relation between the structure and the function of the sight organ. It could be also used to assess patients with impaired retina, optic nerve and neurological deficits. The SAP function is more suitable for the detection and monitoring of neurological deficits, moderately advanced and advanced glaucoma as well as other diseases associated with extensive or deep visual field deficits, such as ischemic optic neuropathy. FDF stimulus was designed specifically to detect early glaucoma-related changes in the visual field. For about a year, the Ophthalmology Clinic in Wrocław has owned a new, unique HEP perimeter. The authors present examples of patients diagnosed and treated at the Clinic, with respect to whom the perimeter results obtained using Octopus type perimeter and HEP contour perimeter have been compared. This method has its advantages: it is non-invasive, objective, provides the opportunity to repeat and compare results obtained from subsequent tests. The disadvantages are the difficulty in adapting to a new stimulus, which is not a circular light stimulus, but an outline that is hard to notice for some patients. Although according to the manufacturer the testing time should not exceed 4-5 minutes, it takes 14-15 minutes in many patients. The test is not suitable for patients showing lower manual skills and less attention and those who tire out easily. The HEP perimeter is an innovative method for diagnosing the earliest changes in ganglion cells, that is pre-perimetric glaucoma, or when changes in the visual field are undetectable in a standard test.

Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis

PubMed Central

Castaldi, E.; Cicchini, G. M.; Cinelli, L.; Rizzo, S.; Morrone, M. C.

2016-01-01

Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI). After surgery, six out of seven retinitis pigmentosa (RP) blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them. No subject showed any improvement of contrast sensitivity in either eye when not using the Argus II. Before the implant, the Blood Oxygenation Level Dependent (BOLD) activity in V1 and the lateral geniculate nucleus (LGN) was very weak or absent. Surprisingly, after prolonged use of Argus II, BOLD responses to visual input were enhanced. This is, to our knowledge, the first study tracking the neural changes of visual areas in patients after retinal implant, revealing a capacity to respond to restored visual input even after years of deprivation. PMID:27780207

Detection of Emotional Faces: Salient Physical Features Guide Effective Visual Search

ERIC Educational Resources Information Center

Calvo, Manuel G.; Nummenmaa, Lauri

2008-01-01

In this study, the authors investigated how salient visual features capture attention and facilitate detection of emotional facial expressions. In a visual search task, a target emotional face (happy, disgusted, fearful, angry, sad, or surprised) was presented in an array of neutral faces. Faster detection of happy and, to a lesser extent,…

Association and comparison between visual inspection and bitewing radiography for the detection of recurrent dental caries under restorations.

PubMed

Lino, José R; Ramos-Jorge, Joana; Coelho, Valéria Silveira; Ramos-Jorge, Maria L; Moysés, Marcos R; Ribeiro, José C R

2015-08-01

The aim of the present study was to investigate, in posterior teeth, the association between the characteristics of the margins of a restoration visually inspected and the presence, under restorations, of recurrent or residual dental caries detected by radiographic examination. Furthermore, the agreement between visual inspection and radiographs to detect dental caries was assessed. Eighty-five permanent molars and premolars with resin restorations on the interproximal and/or occlusal faces, from 18 patients, were submitted for visual inspection and radiographic examination. The visual inspection involved the criteria of the International Caries Detection and Assessment System (ICDAS). Bitewing radiographs were used for the radiographic examination. Logistic regression was used to analyse the association between the characteristics of the margins of a restoration assessed by visual inspection (absence of dental caries, or early, established, inactive and active lesions) and the presence of recurrent caries detected by radiographs. Kappa coefficients were calculated for determining agreement between the two methods. The Kappa coefficient for agreement between visual inspection and radiographic examination was 0.19. Established lesions [odds ratio (OR) = 9.89; 95% confidence interval (95% CI): 2.94-33.25; P < 0.05] and lesion activity (OR = 2.57; 95% CI: 0.91-7.27; P < 0.05) detected by visual inspection, were associated with recurrent or residual dental caries detected by radiographs. Restorations with established and active lesions at the margins had a greater chance of exhibiting recurrent or residual lesions in the radiographic examination. The present findings demonstrate that restorations with established and active lesions at the margins when visually inspected often require removal and retreatment. © 2015 FDI World Dental Federation.