Science.gov

Sample records for perceptual processing stages

  1. Neural Mechanisms of Human Perceptual Learning: Electrophysiological Evidence for a Two-Stage Process

    PubMed Central

    Hamamé, Carlos M.; Cosmelli, Diego; Henriquez, Rodrigo; Aboitiz, Francisco

    2011-01-01

    Background Humans and other animals change the way they perceive the world due to experience. This process has been labeled as perceptual learning, and implies that adult nervous systems can adaptively modify the way in which they process sensory stimulation. However, the mechanisms by which the brain modifies this capacity have not been sufficiently analyzed. Methodology/Principal Findings We studied the neural mechanisms of human perceptual learning by combining electroencephalographic (EEG) recordings of brain activity and the assessment of psychophysical performance during training in a visual search task. All participants improved their perceptual performance as reflected by an increase in sensitivity (d') and a decrease in reaction time. The EEG signal was acquired throughout the entire experiment revealing amplitude increments, specific and unspecific to the trained stimulus, in event-related potential (ERP) components N2pc and P3 respectively. P3 unspecific modification can be related to context or task-based learning, while N2pc may be reflecting a more specific attentional-related boosting of target detection. Moreover, bell and U-shaped profiles of oscillatory brain activity in gamma (30–60 Hz) and alpha (8–14 Hz) frequency bands may suggest the existence of two phases for learning acquisition, which can be understood as distinctive optimization mechanisms in stimulus processing. Conclusions/Significance We conclude that there are reorganizations in several neural processes that contribute differently to perceptual learning in a visual search task. We propose an integrative model of neural activity reorganization, whereby perceptual learning takes place as a two-stage phenomenon including perceptual, attentional and contextual processes. PMID:21541280

  2. Cueing effects on semantic and perceptual categorization: ERPs reveal differential effects of validity as a function of processing stage.

    PubMed

    Lai, Grace; Mangels, Jennifer A

    2007-05-15

    Valid cueing has been shown to accelerate target identification and improve decision accuracy. However, the precise nature and extent to which biasing influences the successive stages of target processing remain unclear. The present event-related potential (ERP) study used a "hybrid" task that combined features of standard cued-attention and task-switching paradigms in order to explore the effects of expectation on both identification and categorization of centrally presented stimuli. Subjects made semantic judgments (living/nonliving) on word targets ("bunny"), and perceptual judgments (right/left) on arrow targets ("<"). Target expectancy was manipulated using cues that were valid (60 percent of trials), invalid (10 percent), or neutral (30 percent). Invalidly cued targets required task-set switching before categorization could commence, and resulted in RT costs relative to validly or neutrally cued targets. Additional benefits from valid-cueing were only observed for word targets. Invalid cueing of both arrow and word targets modulated early posterior visual potentials (P1/N1) and elicited a subsequent anterior P3a (270 ms). The temporal relationship of these effects suggests that the P3a indexed domain-general task-set switching processes recruited in response to the detection of unexpected perceptual information. Subsequent to the P3a and immediately preceding the behavioral response, validly cued targets elicited enhanced stimulus-specific waveforms (arrows: parietal positivity [P290], words: inferior temporal negativity [late ITN: 400-600 ms]). The degree of neural enhancement relative to the invalid and neutral conditions mirrored the magnitude of corresponding RT benefits, suggesting that these waveforms indexed categorization, decision processes or both. Together, these results suggest that valid cueing increases the neural efficiency of initial stimulus identification, facilitating transmission of information to subsequent categorization stages, where

  3. Facial identity and facial expression are initially integrated at visual perceptual stages of face processing.

    PubMed

    Fisher, Katie; Towler, John; Eimer, Martin

    2016-01-01

    It is frequently assumed that facial identity and facial expression are analysed in functionally and anatomically distinct streams within the core visual face processing system. To investigate whether expression and identity interact during the visual processing of faces, we employed a sequential matching procedure where participants compared either the identity or the expression of two successively presented faces, and ignored the other irrelevant dimension. Repetitions versus changes of facial identity and expression were varied independently across trials, and event-related potentials (ERPs) were recorded during task performance. Irrelevant facial identity and irrelevant expression both interfered with performance in the expression and identity matching tasks. These symmetrical interference effects show that neither identity nor expression can be selectively ignored during face matching, and suggest that they are not processed independently. N250r components to identity repetitions that reflect identity matching mechanisms in face-selective visual cortex were delayed and attenuated when there was an expression change, demonstrating that facial expression interferes with visual identity matching. These findings provide new evidence for interactions between facial identity and expression within the core visual processing system, and question the hypothesis that these two attributes are processed independently.

  4. Two-stage perceptual learning to break visual crowding.

    PubMed

    Zhu, Ziyun; Fan, Zhenzhi; Fang, Fang

    2016-01-01

    When a target is presented with nearby flankers in the peripheral visual field, it becomes harder to identify, which is referred to as crowding. Crowding sets a fundamental limit of object recognition in peripheral vision, preventing us from fully appreciating cluttered visual scenes. We trained adult human subjects on a crowded orientation discrimination task and investigated whether crowding could be completely eliminated by training. We discovered a two-stage learning process with this training task. In the early stage, when the target and flankers were separated beyond a certain distance, subjects acquired a relatively general ability to break crowding, as evidenced by the fact that the breaking of crowding could transfer to another crowded orientation, even a crowded motion stimulus, although the transfer to the opposite visual hemi-field was weak. In the late stage, like many classical perceptual learning effects, subjects' performance gradually improved and showed specificity to the trained orientation. We also found that, when the target and flankers were spaced too finely, training could only reduce, rather than completely eliminate, the crowding effect. This two-stage learning process illustrates a learning strategy for our brain to deal with the notoriously difficult problem of identifying peripheral objects in clutter. The brain first learned to solve the "easy and general" part of the problem (i.e., improving the processing resolution and segmenting the target and flankers) and then tackle the "difficult and specific" part (i.e., refining the representation of the target). PMID:27105062

  5. Two-stage perceptual learning to break visual crowding.

    PubMed

    Zhu, Ziyun; Fan, Zhenzhi; Fang, Fang

    2016-01-01

    When a target is presented with nearby flankers in the peripheral visual field, it becomes harder to identify, which is referred to as crowding. Crowding sets a fundamental limit of object recognition in peripheral vision, preventing us from fully appreciating cluttered visual scenes. We trained adult human subjects on a crowded orientation discrimination task and investigated whether crowding could be completely eliminated by training. We discovered a two-stage learning process with this training task. In the early stage, when the target and flankers were separated beyond a certain distance, subjects acquired a relatively general ability to break crowding, as evidenced by the fact that the breaking of crowding could transfer to another crowded orientation, even a crowded motion stimulus, although the transfer to the opposite visual hemi-field was weak. In the late stage, like many classical perceptual learning effects, subjects' performance gradually improved and showed specificity to the trained orientation. We also found that, when the target and flankers were spaced too finely, training could only reduce, rather than completely eliminate, the crowding effect. This two-stage learning process illustrates a learning strategy for our brain to deal with the notoriously difficult problem of identifying peripheral objects in clutter. The brain first learned to solve the "easy and general" part of the problem (i.e., improving the processing resolution and segmenting the target and flankers) and then tackle the "difficult and specific" part (i.e., refining the representation of the target).

  6. Neurological Evidence Linguistic Processes Precede Perceptual Simulation in Conceptual Processing

    PubMed Central

    Louwerse, Max; Hutchinson, Sterling

    2012-01-01

    There is increasing evidence from response time experiments that language statistics and perceptual simulations both play a role in conceptual processing. In an EEG experiment we compared neural activity in cortical regions commonly associated with linguistic processing and visual perceptual processing to determine to what extent symbolic and embodied accounts of cognition applied. Participants were asked to determine the semantic relationship of word pairs (e.g., sky – ground) or to determine their iconic relationship (i.e., if the presentation of the pair matched their expected physical relationship). A linguistic bias was found toward the semantic judgment task and a perceptual bias was found toward the iconicity judgment task. More importantly, conceptual processing involved activation in brain regions associated with both linguistic and perceptual processes. When comparing the relative activation of linguistic cortical regions with perceptual cortical regions, the effect sizes for linguistic cortical regions were larger than those for the perceptual cortical regions early in a trial with the reverse being true later in a trial. These results map upon findings from other experimental literature and provide further evidence that processing of concept words relies both on language statistics and on perceptual simulations, whereby linguistic processes precede perceptual simulation processes. PMID:23133427

  7. Audiovisual speech perception development at varying levels of perceptual processing.

    PubMed

    Lalonde, Kaylah; Holt, Rachael Frush

    2016-04-01

    This study used the auditory evaluation framework [Erber (1982). Auditory Training (Alexander Graham Bell Association, Washington, DC)] to characterize the influence of visual speech on audiovisual (AV) speech perception in adults and children at multiple levels of perceptual processing. Six- to eight-year-old children and adults completed auditory and AV speech perception tasks at three levels of perceptual processing (detection, discrimination, and recognition). The tasks differed in the level of perceptual processing required to complete them. Adults and children demonstrated visual speech influence at all levels of perceptual processing. Whereas children demonstrated the same visual speech influence at each level of perceptual processing, adults demonstrated greater visual speech influence on tasks requiring higher levels of perceptual processing. These results support previous research demonstrating multiple mechanisms of AV speech processing (general perceptual and speech-specific mechanisms) with independent maturational time courses. The results suggest that adults rely on both general perceptual mechanisms that apply to all levels of perceptual processing and speech-specific mechanisms that apply when making phonetic decisions and/or accessing the lexicon. Six- to eight-year-old children seem to rely only on general perceptual mechanisms across levels. As expected, developmental differences in AV benefit on this and other recognition tasks likely reflect immature speech-specific mechanisms and phonetic processing in children. PMID:27106318

  8. Audiovisual speech perception development at varying levels of perceptual processing.

    PubMed

    Lalonde, Kaylah; Holt, Rachael Frush

    2016-04-01

    This study used the auditory evaluation framework [Erber (1982). Auditory Training (Alexander Graham Bell Association, Washington, DC)] to characterize the influence of visual speech on audiovisual (AV) speech perception in adults and children at multiple levels of perceptual processing. Six- to eight-year-old children and adults completed auditory and AV speech perception tasks at three levels of perceptual processing (detection, discrimination, and recognition). The tasks differed in the level of perceptual processing required to complete them. Adults and children demonstrated visual speech influence at all levels of perceptual processing. Whereas children demonstrated the same visual speech influence at each level of perceptual processing, adults demonstrated greater visual speech influence on tasks requiring higher levels of perceptual processing. These results support previous research demonstrating multiple mechanisms of AV speech processing (general perceptual and speech-specific mechanisms) with independent maturational time courses. The results suggest that adults rely on both general perceptual mechanisms that apply to all levels of perceptual processing and speech-specific mechanisms that apply when making phonetic decisions and/or accessing the lexicon. Six- to eight-year-old children seem to rely only on general perceptual mechanisms across levels. As expected, developmental differences in AV benefit on this and other recognition tasks likely reflect immature speech-specific mechanisms and phonetic processing in children.

  9. Neurofeedback training of gamma band oscillations improves perceptual processing.

    PubMed

    Salari, Neda; Büchel, Christian; Rose, Michael

    2014-10-01

    In this study, a noninvasive electroencephalography-based neurofeedback method is applied to train volunteers to deliberately increase gamma band oscillations (40 Hz) in the visual cortex. Gamma band oscillations in the visual cortex play a functional role in perceptual processing. In a previous study, we were able to demonstrate that gamma band oscillations prior to stimulus presentation have a significant influence on perceptual processing of visual stimuli. In the present study, we aimed to investigate longer lasting effects of gamma band neurofeedback training on perceptual processing. For this purpose, a feedback group was trained to modulate oscillations in the gamma band, while a control group participated in a task with an identical design setting but without gamma band feedback. Before and after training, both groups participated in a perceptual object detection task and a spatial attention task. Our results clearly revealed that only the feedback group but not the control group exhibited a visual processing advantage and an increase in oscillatory gamma band activity in the pre-stimulus period of the processing of the visual object stimuli after the neurofeedback training. Results of the spatial attention task showed no difference between the groups, which underlines the specific role of gamma band oscillations for perceptual processing. In summary, our results show that modulation of gamma band activity selectively affects perceptual processing and therefore supports the relevant role of gamma band activity for this specific process. Furthermore, our results demonstrate the eligibility of gamma band oscillations as a valuable tool for neurofeedback applications.

  10. Great expectations: temporal expectation modulates perceptual processing speed.

    PubMed

    Vangkilde, Signe; Coull, Jennifer T; Bundesen, Claus

    2012-10-01

    In a crowded dynamic world, temporal expectations guide our attention in time. Prior investigations have consistently demonstrated that temporal expectations speed motor behavior. We explore effects of temporal expectation on perceptual speed in three nonspeeded, cued recognition paradigms. Different hazard rate functions for the cue-stimulus foreperiod were used to manipulate temporal expectations. By computational modeling we estimated two distinct components of visual attention: the temporal threshold of conscious perception (t₀ ms) and the speed of subsequent encoding into visual short-term memory (v items/s). Notably, these components were measured independently of any motor involvement. The threshold t₀ was unaffected by temporal expectation, but perceptual processing speed v increased with increasing expectation. By employing constant hazard rates to keep expectation constant over time, we further confirmed that the increase in perceptual speed was independent of the cue-stimulus duration. Thus, our results strongly suggest temporal expectations optimize perceptual performance by speeding information processing.

  11. Perceptual Biases in Processing Facial Identity and Emotion

    ERIC Educational Resources Information Center

    Coolican, Jamesie; Eskes, Gail A.; McMullen, Patricia A.; Lecky, Erin

    2008-01-01

    Normal observers demonstrate a bias to process the left sides of faces during perceptual judgments about identity or emotion. This effect suggests a right cerebral hemisphere processing bias. To test the role of the right hemisphere and the involvement of configural processing underlying this effect, young and older control observers and patients…

  12. Perceptual Processing of Partially and Fully Assimilated Words in French

    ERIC Educational Resources Information Center

    Snoeren, Natalie D.; Segui, Juan; Halle, Pierre A.

    2008-01-01

    Models of speech perception attribute a different role to contextual information in the processing of assimilated speech. This study concerned perceptual processing of regressive voice assimilation in French. This phonological variation is asymmetric in that assimilation is partial for voiced stops and nearly complete for voiceless stops. Two…

  13. Two-stage model in perceptual learning: toward a unified theory.

    PubMed

    Shibata, Kazuhisa; Sagi, Dov; Watanabe, Takeo

    2014-05-01

    Training or exposure to a visual feature leads to a long-term improvement in performance on visual tasks that employ this feature. Such performance improvements and the processes that govern them are called visual perceptual learning (VPL). As an ever greater volume of research accumulates in the field, we have reached a point where a unifying model of VPL should be sought. A new wave of research findings has exposed diverging results along three major directions in VPL: specificity versus generalization of VPL, lower versus higher brain locus of VPL, and task-relevant versus task-irrelevant VPL. In this review, we propose a new theoretical model that suggests the involvement of two different stages in VPL: a low-level, stimulus-driven stage, and a higher-level stage dominated by task demands. If experimentally verified, this model would not only constructively unify the current divergent results in the VPL field, but would also lead to a significantly better understanding of visual plasticity, which may, in turn, lead to interventions to ameliorate diseases affecting vision and other pathological or age-related visual and nonvisual declines.

  14. Spatial Attention Enhances Perceptual Processing of Single-Element Displays

    NASA Technical Reports Server (NTRS)

    Bacon, William; Johnston, James C.; Remington, Roger W.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    Shiu and Pashler (1993) reported that precueing masked, single-element displays had negligible effects on identification accuracy. They argued that spatial attention does not actually enhance stimulus perceptibility, but only reduces decision noise. Alternatively, such negative results may arise if cues are sub-optimal, or if masks place an insufficient premium on timely deployment of attention. We report results showing that valid cueing enhances processing of even single-element displays. Spatial attention does indeed enhance perceptual processes.

  15. Semantic Learning Modifies Perceptual Face Processing

    ERIC Educational Resources Information Center

    Heisz, Jennifer J.; Shedden, Judith M.

    2009-01-01

    Face processing changes when a face is learned with personally relevant information. In a five-day learning paradigm, faces were presented with rich semantic stories that conveyed personal information about the faces. Event-related potentials were recorded before and after learning during a passive viewing task. When faces were novel, we observed…

  16. Dissociating sensory from decision processes in human perceptual decision making

    PubMed Central

    Mostert, Pim; Kok, Peter; de Lange, Floris P.

    2015-01-01

    A key question within systems neuroscience is how the brain translates physical stimulation into a behavioral response: perceptual decision making. To answer this question, it is important to dissociate the neural activity underlying the encoding of sensory information from the activity underlying the subsequent temporal integration into a decision variable. Here, we adopted a decoding approach to empirically assess this dissociation in human magnetoencephalography recordings. We used a functional localizer to identify the neural signature that reflects sensory-specific processes, and subsequently traced this signature while subjects were engaged in a perceptual decision making task. Our results revealed a temporal dissociation in which sensory processing was limited to an early time window and consistent with occipital areas, whereas decision-related processing became increasingly pronounced over time, and involved parietal and frontal areas. We found that the sensory processing accurately reflected the physical stimulus, irrespective of the eventual decision. Moreover, the sensory representation was stable and maintained over time when it was required for a subsequent decision, but unstable and variable over time when it was task-irrelevant. In contrast, decision-related activity displayed long-lasting sustained components. Together, our approach dissects neuro-anatomically and functionally distinct contributions to perceptual decisions. PMID:26666393

  17. Processing of unattended, simple negative pictures resists perceptual load.

    PubMed

    Sand, Anders; Wiens, Stefan

    2011-05-11

    As researchers debate whether emotional pictures can be processed irrespective of spatial attention and perceptual load, negative and neutral pictures of simple figure-ground composition were shown at fixation and were surrounded by one, two, or three letters. When participants performed a picture discrimination task, there was evidence for motivated attention; that is, an early posterior negativity (EPN) and late positive potential (LPP) to negative versus neutral pictures. When participants performed a letter discrimination task, the EPN was unaffected whereas the LPP was reduced. Although performance decreased substantially with the number of letters (one to three), the LPP did not decrease further. Therefore, attention to simple, negative pictures at fixation seems to resist manipulations of perceptual load.

  18. Spatiotopic perceptual learning mediated by retinotopic processing and attentional remapping.

    PubMed

    Zhang, En; Zhang, Gong-Liang; Li, Wu

    2013-12-01

    Visual processing takes place in both retinotopic and spatiotopic frames of reference. Whereas visual perceptual learning is usually specific to the trained retinotopic location, our recent study has shown spatiotopic specificity of learning in motion direction discrimination. To explore the mechanisms underlying spatiotopic processing and learning, and to examine whether similar mechanisms also exist in visual form processing, we trained human subjects to discriminate an orientation difference between two successively displayed stimuli, with a gaze shift in between to manipulate their positional relation in the spatiotopic frame of reference without changing their retinal locations. Training resulted in better orientation discriminability for the trained than for the untrained spatial relation of the two stimuli. This learning-induced spatiotopic preference was seen only at the trained retinal location and orientation, suggesting experience-dependent spatiotopic form processing directly based on a retinotopic map. Moreover, a similar but weaker learning-induced spatiotopic preference was still present even if the first stimulus was rendered irrelevant to the orientation discrimination task by having the subjects judge the orientation of the second stimulus relative to its mean orientation in a block of trials. However, if the first stimulus was absent, and thus no attention was captured before the gaze shift, the learning produced no significant spatiotopic preference, suggesting an important role of attentional remapping in spatiotopic processing and learning. Taken together, our results suggest that spatiotopic visual representation can be mediated by interactions between retinotopic processing and attentional remapping, and can be modified by perceptual training.

  19. An alternating renewal process describes the buildup of perceptual segregation

    PubMed Central

    Steele, Sara A.; Tranchina, Daniel; Rinzel, John

    2015-01-01

    For some ambiguous scenes perceptual conflict arises between integration and segregation. Initially, all stimulus features seem integrated. Then abruptly, perhaps after a few seconds, a segregated percept emerges. For example, segregation of acoustic features into streams may require several seconds. In behavioral experiments, when a subject's reports of stream segregation are averaged over repeated trials, one obtains a buildup function, a smooth time course for segregation probability. The buildup function has been said to reflect an underlying mechanism of evidence accumulation or adaptation. During long duration stimuli perception may alternate between integration and segregation. We present a statistical model based on an alternating renewal process (ARP) that generates buildup functions without an accumulative process. In our model, perception alternates during a trial between different groupings, as in perceptual bistability, with random and independent dominance durations sampled from different percept-specific probability distributions. Using this theory, we describe the short-term dynamics of buildup observed on short trials in terms of the long-term statistics of percept durations for the two alternating perceptual organizations. Our statistical-dynamics model describes well the buildup functions and alternations in simulations of pseudo-mechanistic neuronal network models with percept-selective populations competing through mutual inhibition. Even though the competition model can show history dependence through slow adaptation, our statistical switching model, that neglects history, predicts well the buildup function. We propose that accumulation is not a necessary feature to produce buildup. Generally, if alternations between two states exhibit independent durations with stationary statistics then the associated buildup function can be described by the statistical dynamics of an ARP. PMID:25620927

  20. Masked priming of complex movements: perceptual and motor processes in unconscious action perception.

    PubMed

    Güldenpenning, Iris; Braun, Jelena F; Machlitt, Daniel; Schack, Thomas

    2015-09-01

    Fast motor actions in sports often require the ability to discriminate between similar movement patterns (e.g. feint vs. non-feint) at an early stage. Moreover, an athlete might even initiate a motor response without a conscious processing of the relevant movement information. Therefore, the question was raised of whether or not athletes and novices of a particular movement can unconsciously distinguish between similar movement patterns. Using a masked priming experiment (Experiment 1), it is demonstrated that both groups were similarly able to unconsciously distinguish a feint and a non-feint action. To further investigate whether this result is based on perceptual priming effects or on unconscious motor activations, a second masked priming experiment was conducted (Experiment 2). Experiment 2 revealed perceptual priming effects which are not mediated by motor expertise. Moreover, unconscious pictures of feint and non-feint actions from different movement stages are sufficient to activate a motor response in athletes. In novices, a negative congruency effect occurred. For both groups, largest response congruency effects were found for prime pictures participants could consciously perceive as target pictures during the experimental session. The results found here point out that perceptual priming effects are not mediated by motor expertise whereas response priming effects might be. PMID:25187216

  1. Masked priming of complex movements: perceptual and motor processes in unconscious action perception.

    PubMed

    Güldenpenning, Iris; Braun, Jelena F; Machlitt, Daniel; Schack, Thomas

    2015-09-01

    Fast motor actions in sports often require the ability to discriminate between similar movement patterns (e.g. feint vs. non-feint) at an early stage. Moreover, an athlete might even initiate a motor response without a conscious processing of the relevant movement information. Therefore, the question was raised of whether or not athletes and novices of a particular movement can unconsciously distinguish between similar movement patterns. Using a masked priming experiment (Experiment 1), it is demonstrated that both groups were similarly able to unconsciously distinguish a feint and a non-feint action. To further investigate whether this result is based on perceptual priming effects or on unconscious motor activations, a second masked priming experiment was conducted (Experiment 2). Experiment 2 revealed perceptual priming effects which are not mediated by motor expertise. Moreover, unconscious pictures of feint and non-feint actions from different movement stages are sufficient to activate a motor response in athletes. In novices, a negative congruency effect occurred. For both groups, largest response congruency effects were found for prime pictures participants could consciously perceive as target pictures during the experimental session. The results found here point out that perceptual priming effects are not mediated by motor expertise whereas response priming effects might be.

  2. Disrupting perceptual grouping of face parts impairs holistic face processing.

    PubMed

    Curby, Kim M; Goldstein, Rebecca R; Blacker, Kara

    2013-01-01

    Face perception is widely believed to involve integration of facial features into a holistic perceptual unit, but the mechanisms underlying this integration are relatively unknown. We examined whether perceptual grouping cues influence a classic marker of holistic face perception, the "composite-face effect." Participants made same-different judgments about a cued part of sequentially presented chimeric faces, and holistic processing was indexed as the degree to which the task-irrelevant face halves impacted performance. Grouping was encouraged or discouraged by adjusting the backgrounds behind the face halves: Although the face halves were always aligned, their respective backgrounds could be misaligned and of different colors. Holistic processing of face, but not of nonface, stimuli was significantly reduced when the backgrounds were misaligned and of different colors, cues that discouraged grouping of the face halves into a cohesive unit (Exp. 1). This effect was sensitive to stimulus orientation at short (200 ms) but not at long (2,500 ms) encoding durations, consistent with the previously documented temporal properties of the holistic processing of upright and inverted faces (Exps. 2 and 3). These results suggest that grouping mechanisms, typically involved in the perception of objecthood more generally, might contribute in important ways to the holistic perception of faces.

  3. Effect of perceptual load on conceptual processing: an extension of Vermeulen's theory.

    PubMed

    Xie, Jiushu; Wang, Ruiming; Sun, Xun; Chang, Song

    2013-10-01

    The effect of color and shape load on conceptual processing was studied. Perceptual load effects have been found in visual and auditory conceptual processing, supporting the theory of embodied cognition. However, whether different types of visual concepts, such as color and shape, share the same perceptual load effects is unknown. In the current experiment, 32 participants were administered simultaneous perceptual and conceptual tasks to assess the relation between perceptual load and conceptual processing. Keeping color load in mind obstructed color conceptual processing. Hence, perceptual processing and conceptual load shared the same resources, suggesting embodied cognition. Color conceptual processing was not affected by shape pictures, indicating that different types of properties within vision were separate.

  4. Strength of Perceptual Experience Predicts Word Processing Performance Better than Concreteness or Imageability

    ERIC Educational Resources Information Center

    Connell, Louise; Lynott, Dermot

    2012-01-01

    Abstract concepts are traditionally thought to differ from concrete concepts by their lack of perceptual information, which causes them to be processed more slowly and less accurately than perceptually-based concrete concepts. In two studies, we examined this assumption by comparing concreteness and imageability ratings to a set of perceptual…

  5. Differential interference effects of negative emotional states on subsequent semantic and perceptual processing

    PubMed Central

    Gorlick, Marissa A.; Mather, Mara

    2012-01-01

    Past studies have revealed that encountering negative events interferes with cognitive processing of subsequent stimuli. The present study investigated whether negative events affect semantic and perceptual processing differently. Presentation of negative pictures produced slower reaction times than neutral or positive pictures in tasks that require semantic processing, such as natural/man-made judgments about drawings of objects, commonness judgments about objects, and categorical judgments about pairs of words. In contrast, negative picture presentation did not slow down judgments in subsequent perceptual processing (e.g., color judgments about words, and size judgments about objects). The subjective arousal level of negative pictures did not modulate the interference effects on semantic/perceptual processing. These findings indicate that encountering negative emotional events interferes with semantic processing of subsequent stimuli more strongly than perceptual processing, and that not all types of subsequent cognitive processing are impaired by negative events. PMID:22142207

  6. Process and domain specificity in regions engaged for face processing: an fMRI study of perceptual differentiation.

    PubMed

    Collins, Heather R; Zhu, Xun; Bhatt, Ramesh S; Clark, Jonathan D; Joseph, Jane E

    2012-12-01

    The degree to which face-specific brain regions are specialized for different kinds of perceptual processing is debated. This study parametrically varied demands on featural, first-order configural, or second-order configural processing of faces and houses in a perceptual matching task to determine the extent to which the process of perceptual differentiation was selective for faces regardless of processing type (domain-specific account), specialized for specific types of perceptual processing regardless of category (process-specific account), engaged in category-optimized processing (i.e., configural face processing or featural house processing), or reflected generalized perceptual differentiation (i.e., differentiation that crosses category and processing type boundaries). ROIs were identified in a separate localizer run or with a similarity regressor in the face-matching runs. The predominant principle accounting for fMRI signal modulation in most regions was generalized perceptual differentiation. Nearly all regions showed perceptual differentiation for both faces and houses for more than one processing type, even if the region was identified as face-preferential in the localizer run. Consistent with process specificity, some regions showed perceptual differentiation for first-order processing of faces and houses (right fusiform face area and occipito-temporal cortex and right lateral occipital complex), but not for featural or second-order processing. Somewhat consistent with domain specificity, the right inferior frontal gyrus showed perceptual differentiation only for faces in the featural matching task. The present findings demonstrate that the majority of regions involved in perceptual differentiation of faces are also involved in differentiation of other visually homogenous categories.

  7. Supramodal processing optimizes visual perceptual learning and plasticity.

    PubMed

    Zilber, Nicolas; Ciuciu, Philippe; Gramfort, Alexandre; Azizi, Leila; van Wassenhove, Virginie

    2014-06-01

    Multisensory interactions are ubiquitous in cortex and it has been suggested that sensory cortices may be supramodal i.e. capable of functional selectivity irrespective of the sensory modality of inputs (Pascual-Leone and Hamilton, 2001; Renier et al., 2013; Ricciardi and Pietrini, 2011; Voss and Zatorre, 2012). Here, we asked whether learning to discriminate visual coherence could benefit from supramodal processing. To this end, three groups of participants were briefly trained to discriminate which of a red or green intermixed population of random-dot-kinematograms (RDKs) was most coherent in a visual display while being recorded with magnetoencephalography (MEG). During training, participants heard no sound (V), congruent acoustic textures (AV) or auditory noise (AVn); importantly, congruent acoustic textures shared the temporal statistics - i.e. coherence - of visual RDKs. After training, the AV group significantly outperformed participants trained in V and AVn although they were not aware of their progress. In pre- and post-training blocks, all participants were tested without sound and with the same set of RDKs. When contrasting MEG data collected in these experimental blocks, selective differences were observed in the dynamic pattern and the cortical loci responsive to visual RDKs. First and common to all three groups, vlPFC showed selectivity to the learned coherence levels whereas selectivity in visual motion area hMT+ was only seen for the AV group. Second and solely for the AV group, activity in multisensory cortices (mSTS, pSTS) correlated with post-training performances; additionally, the latencies of these effects suggested feedback from vlPFC to hMT+ possibly mediated by temporal cortices in AV and AVn groups. Altogether, we interpret our results in the context of the Reverse Hierarchy Theory of learning (Ahissar and Hochstein, 2004) in which supramodal processing optimizes visual perceptual learning by capitalizing on sensory

  8. Perceptual, Categorical, and Affective Processing of Ambiguous Smiling Facial Expressions

    ERIC Educational Resources Information Center

    Calvo, Manuel G.; Fernandez-Martin, Andres; Nummenmaa, Lauri

    2012-01-01

    Why is a face with a smile but non-happy eyes likely to be interpreted as happy? We used blended expressions in which a smiling mouth was incongruent with the eyes (e.g., angry eyes), as well as genuine expressions with congruent eyes and mouth (e.g., both happy or angry). Tasks involved detection of a smiling mouth (perceptual), categorization of…

  9. Great Expectations: Temporal Expectation Modulates Perceptual Processing Speed

    ERIC Educational Resources Information Center

    Vangkilde, Signe; Coull, Jennifer T.; Bundesen, Claus

    2012-01-01

    In a crowded dynamic world, temporal expectations guide our attention in time. Prior investigations have consistently demonstrated that temporal expectations speed motor behavior. We explore effects of temporal expectation on "perceptual" speed in three nonspeeded, cued recognition paradigms. Different hazard rate functions for the cue-stimulus…

  10. Post-perceptual processing during the attentional blink is modulated by inter-trial task expectancies

    PubMed Central

    Sy, Jocelyn L.; Elliott, James C.; Giesbrecht, Barry

    2013-01-01

    The selective processing of goal-relevant information depends on an attention system that can flexibly adapt to changing task demands and expectations. Evidence from visual search tasks indicates that the perceptual selectivity of attention increases when the bottom-up demands of the task increase and when the expectations about task demands engendered by trial history are violated. Evidence from studies of the attentional blink (AB), which measures the temporal dynamics of attention, also indicates that perceptual selectivity during the AB is increased if the bottom-up task demands are increased. The present work tested whether expectations about task demands engendered by trial history also modulate perceptual selectivity during the AB. Two experiments tested the extent to which inter-trial switches in task demands reduced post-perceptual processing of targets presented during the AB. Experiment 1 indexed post-perceptual processing using the event-related potential (ERP) technique to isolate the context sensitive N400 ERP component evoked by words presented during the AB. Experiment 2 indexed post-perceptual processing using behavioral performance to determine the extent to which personal names survive the AB. The results of both experiments revealed that both electrophysiological (Exp. 1) and behavioral (Exp. 2) indices of post-perceptual processing were attenuated when consecutive trials differed in terms of their perceptual demands. The results are consistent with the notion that the selectivity of attention during the AB is modulated not only by within-trial task demands, but also can be flexibly determined by trial-by-trial expectations. PMID:24115924

  11. Predicting perceptual learning from higher-order cortical processing.

    PubMed

    Wang, Fang; Huang, Jing; Lv, Yaping; Ma, Xiaoli; Yang, Bin; Wang, Encong; Du, Boqi; Li, Wu; Song, Yan

    2016-01-01

    Visual perceptual learning has been shown to be highly specific to the retinotopic location and attributes of the trained stimulus. Recent psychophysical studies suggest that these specificities, which have been associated with early retinotopic visual cortex, may in fact not be inherent in perceptual learning and could be related to higher-order brain functions. Here we provide direct electrophysiological evidence in support of this proposition. In a series of event-related potential (ERP) experiments, we recorded high-density electroencephalography (EEG) from human adults over the course of learning in a texture discrimination task (TDT). The results consistently showed that the earliest C1 component (68-84ms), known to reflect V1 activity driven by feedforward inputs, was not modulated by learning regardless of whether the behavioral improvement is location specific or not. In contrast, two later posterior ERP components (posterior P1 and P160-350) over the occipital cortex and one anterior ERP component (anterior P160-350) over the prefrontal cortex were progressively modified day by day. Moreover, the change of the anterior component was closely correlated with improved behavioral performance on a daily basis. Consistent with recent psychophysical and imaging observations, our results indicate that perceptual learning can mainly involve changes in higher-level visual cortex as well as in the neural networks responsible for cognitive functions such as attention and decision making.

  12. Enhanced cognitive and perceptual processing: a computational basis for the musician advantage in speech learning.

    PubMed

    Smayda, Kirsten E; Chandrasekaran, Bharath; Maddox, W Todd

    2015-01-01

    Long-term music training can positively impact speech processing. A recent framework developed to explain such cross-domain plasticity posits that music training-related advantages in speech processing are due to shared cognitive and perceptual processes between music and speech. Although perceptual and cognitive processing advantages due to music training have been independently demonstrated, to date no study has examined perceptual and cognitive processing within the context of a single task. The present study examines the impact of long-term music training on speech learning from a rigorous, computational perspective derived from signal detection theory. Our computational models provide independent estimates of cognitive and perceptual processing in native English-speaking musicians (n = 15, mean age = 25 years) and non-musicians (n = 15, mean age = 23 years) learning to categorize non-native lexical pitch patterns (Mandarin tones). Musicians outperformed non-musicians in this task. Model-based analyses suggested that musicians shifted from simple unidimensional decision strategies to more optimal multidimensional (MD) decision strategies sooner than non-musicians. In addition, musicians used optimal decisional strategies more often than non-musicians. However, musicians and non-musicians who used MD strategies showed no difference in performance. We estimated parameters that quantify the magnitude of perceptual variability along two dimensions that are critical for tone categorization: pitch height and pitch direction. Both musicians and non-musicians showed a decrease in perceptual variability along the pitch height dimension, but only musicians showed a significant reduction in perceptual variability along the pitch direction dimension. Notably, these advantages persisted during a generalization phase, when no feedback was provided. These results provide an insight into the mechanisms underlying the musician advantage observed in non-native speech learning

  13. Enhanced cognitive and perceptual processing: a computational basis for the musician advantage in speech learning

    PubMed Central

    Smayda, Kirsten E.; Chandrasekaran, Bharath; Maddox, W. Todd

    2015-01-01

    Long-term music training can positively impact speech processing. A recent framework developed to explain such cross-domain plasticity posits that music training-related advantages in speech processing are due to shared cognitive and perceptual processes between music and speech. Although perceptual and cognitive processing advantages due to music training have been independently demonstrated, to date no study has examined perceptual and cognitive processing within the context of a single task. The present study examines the impact of long-term music training on speech learning from a rigorous, computational perspective derived from signal detection theory. Our computational models provide independent estimates of cognitive and perceptual processing in native English-speaking musicians (n = 15, mean age = 25 years) and non-musicians (n = 15, mean age = 23 years) learning to categorize non-native lexical pitch patterns (Mandarin tones). Musicians outperformed non-musicians in this task. Model-based analyses suggested that musicians shifted from simple unidimensional decision strategies to more optimal multidimensional (MD) decision strategies sooner than non-musicians. In addition, musicians used optimal decisional strategies more often than non-musicians. However, musicians and non-musicians who used MD strategies showed no difference in performance. We estimated parameters that quantify the magnitude of perceptual variability along two dimensions that are critical for tone categorization: pitch height and pitch direction. Both musicians and non-musicians showed a decrease in perceptual variability along the pitch height dimension, but only musicians showed a significant reduction in perceptual variability along the pitch direction dimension. Notably, these advantages persisted during a generalization phase, when no feedback was provided. These results provide an insight into the mechanisms underlying the musician advantage observed in non-native speech learning

  14. Relative Saliency in Change Signals Affects Perceptual Comparison and Decision Processes in Change Detection

    ERIC Educational Resources Information Center

    Yang, Cheng-Ta

    2011-01-01

    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…

  15. Tactile and Kinesthetic Perceptual Processes within the Taxonomy of Human Cognitive Abilities.

    ERIC Educational Resources Information Center

    Stankov, Lazar; Seizova-Cajic, Tatjana; Roberts, Richard D.

    2001-01-01

    Examined critical features of tactile and kinesthetic processes by administering 8 traditional psychometric instruments and 14 measures of tactile and kinesthetic perceptual processes to 116 female college students in Australia. Results show, as is consistent with earlier findings, that visual-spatial processes are difficult to separate from…

  16. Experience shapes our odor perception but depends on the initial perceptual processing of the stimulus.

    PubMed

    Sinding, Charlotte; Coureaud, Gérard; Bervialle, Boris; Martin, Christophe; Schaal, Benoist; Thomas-Danguin, Thierry

    2015-07-01

    The questions of whether configural and elemental perceptions are competitive or exclusive perceptual processes and whether they rely on independent or dependent mechanisms are poorly understood. To examine these questions, we modified perceptual experience through preexposure to mixed or single odors and measured the resulting variation in the levels of configural and elemental perception of target odor mixtures. We used target mixtures that were spontaneously processed in a configural or an elemental manner. The AB binary mixture spontaneously involved the configural perception of a pineapple odor, whereas component A smelled like strawberry and component B smelled like caramel. The CD mixture produced the elemental perceptions of banana (C) and smoky (D) odors. Perceptual experience was manipulated through repeated exposure to either a mixture (AB or CD) or the components (A and B or C and D). The odor typicality rating data recorded after exposure revealed different influences of experience on odor mixtures and single-component perception, depending both on the type of exposure (components or mixture) and the mixture's initial perceptual property (configural or elemental). Although preexposure to A and B decreased the pineapple typicality of the configural AB mixture, preexposure to AB did not modify its odor quality. In contrast, preexposure to the CD elemental mixture induced a quality transfer between the components. These results emphasize the relative plasticity of odor mixture perception, which is prone to experience-induced modulations but depends on the stimulus's initial perceptual properties, suggesting that configural and elemental forms of odor mixture perception rely on rather independent processes.

  17. Stages in the research process.

    PubMed

    Gelling, Leslie

    2015-03-01

    Research should be conducted in a systematic manner, allowing the researcher to progress from a general idea or clinical problem to scientifically rigorous research findings that enable new developments to improve clinical practice. Using a research process helps guide this process. This article is the first in a 26-part series on nursing research. It examines the process that is common to all research, and provides insights into ten different stages of this process: developing the research question, searching and evaluating the literature, selecting the research approach, selecting research methods, gaining access to the research site and data, pilot study, sampling and recruitment, data collection, data analysis, and dissemination of results and implementation of findings.

  18. Task-Set Reconfiguration and Perceptual Processing: Behavioral and Electrophysiological Evidence

    ERIC Educational Resources Information Center

    Mackenzie, Ian G.; Leuthold, Hartmut

    2011-01-01

    Oriet and Jolicoeur (2003) proposed that an endogenous task-set reconfiguration process acts as a hard bottleneck during which even early perceptual processing is impossible. We examined this assumption using a psychophysiological approach. Participants were required to switch between magnitude and parity judgment tasks within a predictable task…

  19. Perceptual chunking and its effect on memory in speech processing: ERP and behavioral evidence.

    PubMed

    Gilbert, Annie C; Boucher, Victor J; Jemel, Boutheina

    2014-01-01

    We examined how perceptual chunks of varying size in utterances can influence immediate memory of heard items (monosyllabic words). Using behavioral measures and event-related potentials (N400) we evaluated the quality of the memory trace for targets taken from perceived temporal groups (TGs) of three and four items. Variations in the amplitude of the N400 showed a better memory trace for items presented in TGs of three compared to those in groups of four. Analyses of behavioral responses along with P300 components also revealed effects of chunk position in the utterance. This is the first study to measure the online effects of perceptual chunks on the memory trace of spoken items. Taken together, the N400 and P300 responses demonstrate that the perceptual chunking of speech facilitates information buffering and a processing on a chunk-by-chunk basis.

  20. A Developmental Examination of Basic Perceptual Processes in Reading. Final Report.

    ERIC Educational Resources Information Center

    Lefton, Lester A.

    This report summarizes four groups of experiments examining the nature of basic perceptual processes in reading. The first group examined the relationship of English orthography to reading, specifically the transfer of information from the icon to short-term memory. The second group of experiments examined the use of peripheral information…

  1. The Development of Automatic Numerosity Processing in Preschoolers: Evidence for Numerosity-Perceptual Interference

    ERIC Educational Resources Information Center

    Rousselle, Laurence; Noel, Marie-Pascale

    2008-01-01

    Three experiments examined developmental changes in the automatic processing of numerosity and perceptual information using a nonsymbolic numerical Stroop paradigm. In Experiments 1 and 2 (E1 and E2), 4-, 5-, and 6-year-olds had to compare the numerosities or the total filled areas of collections of dots (E1) or bars (E2) varying along both…

  2. Outlining face processing skills of portrait artists: Perceptual experience with faces predicts performance.

    PubMed

    Devue, Christel; Barsics, Catherine

    2016-10-01

    Most humans seem to demonstrate astonishingly high levels of skill in face processing if one considers the sophisticated level of fine-tuned discrimination that face recognition requires. However, numerous studies now indicate that the ability to process faces is not as fundamental as once thought and that performance can range from despairingly poor to extraordinarily high across people. Here we studied people who are super specialists of faces, namely portrait artists, to examine how their specific visual experience with faces relates to a range of face processing skills (perceptual discrimination, short- and longer term recognition). Artists show better perceptual discrimination and, to some extent, recognition of newly learned faces than controls. They are also more accurate on other perceptual tasks (i.e., involving non-face stimuli or mental rotation). By contrast, artists do not display an advantage compared to controls on longer term face recognition (i.e., famous faces) nor on person recognition from other sensorial modalities (i.e., voices). Finally, the face inversion effect exists in artists and controls and is not modulated by artistic practice. Advantages in face processing for artists thus seem to closely mirror perceptual and visual short term memory skills involved in portraiture.

  3. Perceptual Processing of Mandarin Nasals by L1 and L2 Mandarin Speakers

    ERIC Educational Resources Information Center

    Lai, Yi-hsiu

    2012-01-01

    Nasals are cross-linguistically susceptible to change, especially in the syllable final position. Acoustic reports on Mandarin nasal production have recently shown that the syllable-final distinction is frequently dropped. Few studies, however, have addressed the issue of perceptual processing in Mandarin nasals for L1 and L2 speakers of Mandarin…

  4. Processing Capacity under Perceptual and Cognitive Load: A Closer Look at Load Theory

    ERIC Educational Resources Information Center

    Fitousi, Daniel; Wenger, Michael J.

    2011-01-01

    Variations in perceptual and cognitive demands (load) play a major role in determining the efficiency of selective attention. According to load theory (Lavie, Hirst, Fockert, & Viding, 2004) these factors (a) improve or hamper selectivity by altering the way resources (e.g., processing capacity) are allocated, and (b) tap resources rather than…

  5. Automatic Processing of Perceptual-Linguistic Stimuli in Second Grade Achieving and Non-Achieving Readers.

    ERIC Educational Resources Information Center

    Swallow, Rose-Marie

    This study examined automatic processing of perceptual stimuli (auditory, visual, auditory-visual) and of linguistic units (morphological rules, grammatical structures, and syntactical control). Sixty average (85-115 IQ), Caucasian, middle class, eight-year-old boys were selected from La Habra School District second grades. The testing instruments…

  6. Outlining face processing skills of portrait artists: Perceptual experience with faces predicts performance.

    PubMed

    Devue, Christel; Barsics, Catherine

    2016-10-01

    Most humans seem to demonstrate astonishingly high levels of skill in face processing if one considers the sophisticated level of fine-tuned discrimination that face recognition requires. However, numerous studies now indicate that the ability to process faces is not as fundamental as once thought and that performance can range from despairingly poor to extraordinarily high across people. Here we studied people who are super specialists of faces, namely portrait artists, to examine how their specific visual experience with faces relates to a range of face processing skills (perceptual discrimination, short- and longer term recognition). Artists show better perceptual discrimination and, to some extent, recognition of newly learned faces than controls. They are also more accurate on other perceptual tasks (i.e., involving non-face stimuli or mental rotation). By contrast, artists do not display an advantage compared to controls on longer term face recognition (i.e., famous faces) nor on person recognition from other sensorial modalities (i.e., voices). Finally, the face inversion effect exists in artists and controls and is not modulated by artistic practice. Advantages in face processing for artists thus seem to closely mirror perceptual and visual short term memory skills involved in portraiture. PMID:27507580

  7. Action video games do not improve the speed of information processing in simple perceptual tasks.

    PubMed

    van Ravenzwaaij, Don; Boekel, Wouter; Forstmann, Birte U; Ratcliff, Roger; Wagenmakers, Eric-Jan

    2014-10-01

    Previous research suggests that playing action video games improves performance on sensory, perceptual, and attentional tasks. For instance, Green, Pouget, and Bavelier (2010) used the diffusion model to decompose data from a motion detection task and estimate the contribution of several underlying psychological processes. Their analysis indicated that playing action video games leads to faster information processing, reduced response caution, and no difference in motor responding. Because perceptual learning is generally thought to be highly context-specific, this transfer from gaming is surprising and warrants corroborative evidence from a large-scale training study. We conducted 2 experiments in which participants practiced either an action video game or a cognitive game in 5 separate, supervised sessions. Prior to each session and following the last session, participants performed a perceptual discrimination task. In the second experiment, we included a third condition in which no video games were played at all. Behavioral data and diffusion model parameters showed similar practice effects for the action gamers, the cognitive gamers, and the nongamers and suggest that, in contrast to earlier reports, playing action video games does not improve the speed of information processing in simple perceptual tasks.

  8. Action Video Games Do Not Improve the Speed of Information Processing in Simple Perceptual Tasks

    PubMed Central

    van Ravenzwaaij, Don; Boekel, Wouter; Forstmann, Birte U.; Ratcliff, Roger; Wagenmakers, Eric-Jan

    2015-01-01

    Previous research suggests that playing action video games improves performance on sensory, perceptual, and attentional tasks. For instance, Green, Pouget, and Bavelier (2010) used the diffusion model to decompose data from a motion detection task and estimate the contribution of several underlying psychological processes. Their analysis indicated that playing action video games leads to faster information processing, reduced response caution, and no difference in motor responding. Because perceptual learning is generally thought to be highly context-specific, this transfer from gaming is surprising and warrants corroborative evidence from a large-scale training study. We conducted 2 experiments in which participants practiced either an action video game or a cognitive game in 5 separate, supervised sessions. Prior to each session and following the last session, participants performed a perceptual discrimination task. In the second experiment, we included a third condition in which no video games were played at all. Behavioral data and diffusion model parameters showed similar practice effects for the action gamers, the cognitive gamers, and the nongamers and suggest that, in contrast to earlier reports, playing action video games does not improve the speed of information processing in simple perceptual tasks. PMID:24933517

  9. The role of semantic abstractness and perceptual category in processing speech accompanied by gestures

    PubMed Central

    Nagels, Arne; Chatterjee, Anjan; Kircher, Tilo; Straube, Benjamin

    2013-01-01

    Space and shape are distinct perceptual categories. In language, perceptual information can also be used to describe abstract semantic concepts like a “rising income” (space) or a “square personality” (shape). Despite being inherently concrete, co-speech gestures depicting space and shape can accompany concrete or abstract utterances. Here, we investigated the way that abstractness influences the neural processing of the perceptual categories of space and shape in gestures. Thus, we tested the hypothesis that the neural processing of perceptual categories is highly dependent on language context. In a two-factorial design, we investigated the neural basis for the processing of gestures containing shape (SH) and spatial information (SP) when accompanying concrete (c) or abstract (a) verbal utterances. During fMRI data acquisition participants were presented with short video clips of the four conditions (cSP, aSP, cSH, aSH) while performing an independent control task. Abstract (a) as opposed to concrete (c) utterances activated temporal lobes bilaterally and the left inferior frontal gyrus (IFG) for both shape-related (SH) and space-related (SP) utterances. An interaction of perceptual category and semantic abstractness in a more anterior part of the left IFG and inferior part of the posterior temporal lobe (pTL) indicates that abstractness strongly influenced the neural processing of space and shape information. Despite the concrete visual input of co-speech gestures in all conditions, space and shape information is processed differently depending on the semantic abstractness of its linguistic context. PMID:24391560

  10. From perceptual to lexico-semantic analysis--cortical plasticity enabling new levels of processing.

    PubMed

    Schlaffke, Lara; Rüther, Naima N; Heba, Stefanie; Haag, Lauren M; Schultz, Thomas; Rosengarth, Katharina; Tegenthoff, Martin; Bellebaum, Christian; Schmidt-Wilcke, Tobias

    2015-11-01

    Certain kinds of stimuli can be processed on multiple levels. While the neural correlates of different levels of processing (LOPs) have been investigated to some extent, most of the studies involve skills and/or knowledge already present when performing the task. In this study we specifically sought to identify neural correlates of an evolving skill that allows the transition from perceptual to a lexico-semantic stimulus analysis. Eighteen participants were trained to decode 12 letters of Morse code that were presented acoustically inside and outside of the scanner environment. Morse code was presented in trains of three letters while brain activity was assessed with fMRI. Participants either attended to the stimulus length (perceptual analysis), or evaluated its meaning distinguishing words from nonwords (lexico-semantic analysis). Perceptual and lexico-semantic analyses shared a mutual network comprising the left premotor cortex, the supplementary motor area (SMA) and the inferior parietal lobule (IPL). Perceptual analysis was associated with a strong brain activation in the SMA and the superior temporal gyrus bilaterally (STG), which remained unaltered from pre and post training. In the lexico-semantic analysis post learning, study participants showed additional activation in the left inferior frontal cortex (IFC) and in the left occipitotemporal cortex (OTC), regions known to be critically involved in lexical processing. Our data provide evidence for cortical plasticity evolving with a learning process enabling the transition from perceptual to lexico-semantic stimulus analysis. Importantly, the activation pattern remains task-related LOP and is thus the result of a decision process as to which LOP to engage in.

  11. From perceptual to lexico‐semantic analysis—cortical plasticity enabling new levels of processing

    PubMed Central

    Schlaffke, Lara; Rüther, Naima N.; Heba, Stefanie; Haag, Lauren M.; Schultz, Thomas; Rosengarth, Katharina; Tegenthoff, Martin; Bellebaum, Christian

    2015-01-01

    Abstract Certain kinds of stimuli can be processed on multiple levels. While the neural correlates of different levels of processing (LOPs) have been investigated to some extent, most of the studies involve skills and/or knowledge already present when performing the task. In this study we specifically sought to identify neural correlates of an evolving skill that allows the transition from perceptual to a lexico‐semantic stimulus analysis. Eighteen participants were trained to decode 12 letters of Morse code that were presented acoustically inside and outside of the scanner environment. Morse code was presented in trains of three letters while brain activity was assessed with fMRI. Participants either attended to the stimulus length (perceptual analysis), or evaluated its meaning distinguishing words from nonwords (lexico‐semantic analysis). Perceptual and lexico‐semantic analyses shared a mutual network comprising the left premotor cortex, the supplementary motor area (SMA) and the inferior parietal lobule (IPL). Perceptual analysis was associated with a strong brain activation in the SMA and the superior temporal gyrus bilaterally (STG), which remained unaltered from pre and post training. In the lexico‐semantic analysis post learning, study participants showed additional activation in the left inferior frontal cortex (IFC) and in the left occipitotemporal cortex (OTC), regions known to be critically involved in lexical processing. Our data provide evidence for cortical plasticity evolving with a learning process enabling the transition from perceptual to lexico‐semantic stimulus analysis. Importantly, the activation pattern remains task‐related LOP and is thus the result of a decision process as to which LOP to engage in. Hum Brain Mapp 36:4512–4528, 2015. © 2015 The Authors. Human Brain Mapping Published byWiley Periodicals, Inc. PMID:26304153

  12. Multiple stages of learning in perceptual categorization: evidence and neurocomputational theory.

    PubMed

    Cantwell, George; Crossley, Matthew J; Ashby, F Gregory

    2015-12-01

    Virtually all current theories of category learning assume that humans learn new categories by gradually forming associations directly between stimuli and responses. In information-integration category-learning tasks, this purported process is thought to depend on procedural learning implemented via dopamine-dependent cortical-striatal synaptic plasticity. This article proposes a new, neurobiologically detailed model of procedural category learning that, unlike previous models, does not assume associations are made directly from stimulus to response. Rather, the traditional stimulus-response (S-R) models are replaced with a two-stage learning process. Multiple streams of evidence (behavioral, as well as anatomical and fMRI) are used as inspiration for the new model, which synthesizes evidence of multiple distinct cortical-striatal loops into a neurocomputational theory. An experiment is reported to test a priori predictions of the new model that: (1) recovery from a full reversal should be easier than learning new categories equated for difficulty, and (2) reversal learning in procedural tasks is mediated within the striatum via dopamine-dependent synaptic plasticity. The results confirm the predictions of the new two-stage model and are incompatible with existing S-R models.

  13. Interference in character processing reflects common perceptual expertise across writing systems.

    PubMed

    Wong, Alan C-N; Qu, Zhiyi; McGugin, Rankin W; Gauthier, Isabel

    2011-01-01

    Perceptual expertise, even within the visual domain, can take many forms, depending on the goals of the practiced task and the visual information available to support performance. Given the same goals, expertise for different categories can recruit common perceptual resources, which could lead to interference during concurrent processing. We measured whether irrelevant characters of one writing system produce interference during visual search for characters of another writing system, as a function of expertise. Chinese-English bilinguals and English readers searched for target Roman letters among other distractors in a rapid serial visual presentation (RSVP) sequence. Chinese character distractors interfered with Roman letter search more than pseudoletter distractors, only for bilingual readers, suggesting a common perceptual bottleneck for Roman and Chinese processing in experts with both domains. We ruled out an explanation at the level of phonetic codes, by showing that concurrent verbal rehearsal has no effect on the magnitude of such interference. These findings converge with results showing competition between faces and cars in car experts to suggest that different domains of expertise that overlap in their cortical representations also possess a common perceptual bottleneck. PMID:21245276

  14. Neural correlates of perceptual grouping effects in the processing of sound omission by musicians and nonmusicians.

    PubMed

    Ono, Kentaro; Altmann, Christian F; Matsuhashi, Masao; Mima, Tatsuya; Fukuyama, Hidenao

    2015-01-01

    Perceptual grouping is the process of organizing sounds into perceptually meaningful elements. Psychological studies have found that tones presented as a regular frequency or temporal pattern are grouped according to gestalt principles, such as similarity, proximity, and good continuity. Predictive coding theory suggests that this process helps create an internal model for the prediction of sounds in a tone sequence and that an omission-related brain response reflects the violation of this prediction. However, it remains unclear which brain areas are related to this process, especially in paying attention to the stimuli. To clarify this uncertainty, the present study investigated the neural correlates of perceptual grouping effects. Using magnetoencephalography (MEG), we recorded the evoked response fields (ERFs) of amateur musicians and nonmusicians to sound omissions in tone sequences with a regular or random pattern of three different frequencies during an omission detection task. Omissions in the regular sequences were detected faster and evoked greater activity in the left Heschl's gyrus (HG), right postcentral gyrus, and bilateral superior temporal gyrus (STG) than did omissions in the irregular sequences. Additionally, an interaction between musical experience and regularity was found in the left HG/STG. Tone-evoked responses did not show this difference, indicating that the expertise effect did not reflect the superior tone processing acquired by amateur musicians due to musical training. These results suggest that perceptual grouping based on repetition of a pattern of frequencies affects the processing of omissions in tone sequences and induces more activation of the bilateral auditory cortex by violating internal models. The interaction in the left HG/STG may suggest different styles of processing for musicians and nonmusicians, although this difference was not reflected at the behavioral level. PMID:25446245

  15. Motor and perceptual sequence learning: different time course of parallel processes.

    PubMed

    Dirnberger, Georg; Novak-Knollmueller, Judith

    2013-07-10

    The aim was to determine the extent and time course of motor and perceptual learning in a procedural learning task, and the relation of these two processes. Because environmental constraints modulate the relative impact of different learning mechanisms, we chose a simple learning task similar to real-life exercise. Thirty-four healthy individuals performed a visuomotor serial reaction time task. Learning blocks with high stimulus-response compatibility were practiced repeatedly; in between these, participants performed test blocks with the same or a different (mirror-inverted, or new) stimulus sequence and/or with the same or a different (mirror-inverted) stimulus-response allocation. This design allowed us to measure the progress of motor learning and perceptual learning independently. Results showed that in the learning blocks, a steady reduction of the reaction times indicated that - as expected - participants improved their skills continuously. Analysis of the test blocks indicated that both motor learning and perceptual learning were significant. The two mechanisms were correlated (r=0.62, P<0.001). However, their time course was different: the impact of motor learning increased strongly from earlier to later intervals, whereas the progress of perceptual learning was more stable but slower. In conclusion, in a simple visuomotor learning task, participants can learn the motor sequence and the stimulus sequence in parallel. The positive correlation of motor and perceptual learning suggests that the two mechanisms act in synergy and are not alternative opposing strategies. The impact of these two learning mechanisms changes over time: motor learning sets in later and becomes relevant only in the course of training.

  16. Holistic Processing of Faces: Perceptual and Decisional Components

    ERIC Educational Resources Information Center

    Richler, Jennifer J.; Gauthier, Isabel; Wenger, Michael J.; Palmeri, Thomas J.

    2008-01-01

    Researchers have used several composite face paradigms to assess holistic processing of faces. In the selective attention paradigm, participants decide whether one face part (e.g., top) is the same as a previously seen face part. Their judgment is affected by whether the irrelevant part of the test face is the same as or different than the…

  17. The Impact of Perceptual Load on the Non-Conscious Processing of Fearful Faces

    PubMed Central

    Wang, Lili; Feng, Chunliang; Mai, Xiaoqin; Jia, Lina; Zhu, Xiangru; Luo, Wenbo; Luo, Yue-jia

    2016-01-01

    Emotional stimuli can be processed without consciousness. In the current study, we used event-related potentials (ERPs) to assess whether perceptual load influences non-conscious processing of fearful facial expressions. Perceptual load was manipulated using a letter search task with the target letter presented at the fixation point, while facial expressions were presented peripherally and masked to prevent conscious awareness. The letter string comprised six letters (X or N) that were identical (low load) or different (high load). Participants were instructed to discriminate the letters at fixation or the facial expression (fearful or neutral) in the periphery. Participants were faster and more accurate at detecting letters in the low load condition than in the high load condition. Fearful faces elicited a sustained positivity from 250 ms to 700 ms post-stimulus over fronto-central areas during the face discrimination and low-load letter discrimination conditions, but this effect was completely eliminated during high-load letter discrimination. Our findings imply that non-conscious processing of fearful faces depends on perceptual load, and attentional resources are necessary for non-conscious processing. PMID:27149273

  18. Differences in early sensory-perceptual processing in synesthesia: a visual evoked potential study.

    PubMed

    Barnett, Kylie J; Foxe, John J; Molholm, Sophie; Kelly, Simon P; Shalgi, Shani; Mitchell, Kevin J; Newell, Fiona N

    2008-11-15

    Synesthesia is a condition where stimulation of a single sensory modality or processing stream elicits an idiosyncratic, yet reliable perception in one or more other modalities or streams. Various models have been proposed to explain synesthesia, which have in common aberrant cross-activation of one cortical area by another. This has been observed directly in cases of linguistic-color synesthesia as cross-activation of the 'color area', V4, by stimulation of the grapheme area. The underlying neural substrates that mediate cross-activations in synesthesia are not well understood, however. In addition, the overall integrity of the visual system has never been assessed and it is not known whether wider differences in sensory-perceptual processing are associated with the condition. To assess whether fundamental differences in perceptual processing exist in synesthesia, we utilised high-density 128-channel electroencephalography (EEG) to measure sensory-perceptual processing using stimuli that differentially bias activation of the magnocellular and parvocellular pathways of the visual system. High and low spatial frequency gratings and luminance-contrast squares were presented to 15 synesthetes and 15 controls. We report, for the first time, early sensory-perceptual differences in synesthetes relative to non-synesthete controls in response to simple stimuli that do not elicit synesthetic color experiences. The differences are manifested in the early sensory components of the visual evoked potential (VEP) to stimuli that bias both magnocellular and parvocellular responses, but are opposite in direction, suggesting a differential effect on these two pathways. We discuss our results with reference to widespread connectivity differences as a broader phenotype of synesthesia.

  19. Configural processing at birth: evidence for perceptual organisation.

    PubMed

    Farroni, T; Valenza, E; Simion, F; Umiltà, C

    2000-01-01

    We report a series of ten experiments aimed to investigate the newborn's ability to discriminate the components of a visual pattern and to process the visual information that specifies the global configuration of a stimulus. The results reveal that: (i) newborn babies are able to distinguish individual elements of a stimulus (experiments 1A, 1B, 1C, and 1D); (ii) they can group individual elements into a holistic percept on the basis of Gestalt principles (experiments 2A and 3A); (iii) their spontaneous preferences cannot be easily modified by habituation (experiments 2B and 3B); and (iv) when horizontal stimuli are paired with vertical stimuli, they prefer the horizontal ones (experiments 4A and 4B).

  20. Age-related face processing bias in infancy: evidence of perceptual narrowing for adult faces.

    PubMed

    Macchi Cassia, Viola; Bulf, Hermann; Quadrelli, Ermanno; Proietti, Valentina

    2014-02-01

    Recent data demonstrate a perceptual processing advantage for adult faces in both adults and young children, suggesting that face representation is shaped by visual experience accumulated with different face-age groups. As for species and race, this age bias may emerge during the first year of life as part of the general process of perceptual narrowing, given the extensive amount of social and perceptual experience accumulated with caregivers and/or other adult individuals. Using infant-controlled habituation and visual-paired comparison at test, two experiments were carried out to examine 3- and 9-month-olds' ability to discriminate within adult and infant faces. Results showed that, when they are provided with adequate time to visually compare the stimuli during test trials (Experiment 2), 3-month-olds exhibit above-chance discrimination of adult and infant faces. Instead, 9-month-olds discriminate adult faces but not infant faces (Experiments 1 and 2). Results provide the first evidence of age-related face processing biases in infancy, and show that by 9 months face representations tune to adult human faces. PMID:24374735

  1. Instruction-driven processing in human perceptual learning.

    PubMed

    Navarro, Anton; Arriola, Naiara; Alonso, Gumersinda

    2016-01-01

    We conducted a series of experiments to determine the relative contribution of unsupervised versus controlled mechanisms to the intermixed-blocked effect. In Experiment 1, participants received pre-exposure instructions prompting a search for differences between stimuli, in keeping with past studies, and the intermixed-blocked effect was observed. In the remaining experiments, participants did not receive the aforementioned instructions, but instead were instructed either to simply observe the stimuli (Experiment 2) or in relation to a masking task (Experiment 3). None of the latter experiments produced an intermixed-blocked effect, suggesting that the effect found in Experiment 1 was driven by the instructions to search for differences, consistent with a controlled processing account of the effect. Moreover, we tested a prediction assuming the operation of a search strategy against one assuming the operation of a short-term habituation mechanism and found evidence more consistent with the search strategy hypothesis. We formulate a new account of the intermixed-blocked effect in humans based on an instruction-driven search and discuss how the account could explain many findings in the human literature.

  2. Second stage gasifier in staged gasification and integrated process

    SciTech Connect

    Liu, Guohai; Vimalchand, Pannalal; Peng, Wan Wang

    2015-10-06

    A second stage gasification unit in a staged gasification integrated process flow scheme and operating methods are disclosed to gasify a wide range of low reactivity fuels. The inclusion of second stage gasification unit operating at high temperatures closer to ash fusion temperatures in the bed provides sufficient flexibility in unit configurations, operating conditions and methods to achieve an overall carbon conversion of over 95% for low reactivity materials such as bituminous and anthracite coals, petroleum residues and coke. The second stage gasification unit includes a stationary fluidized bed gasifier operating with a sufficiently turbulent bed of predefined inert bed material with lean char carbon content. The second stage gasifier fluidized bed is operated at relatively high temperatures up to 1400.degree. C. Steam and oxidant mixture can be injected to further increase the freeboard region operating temperature in the range of approximately from 50 to 100.degree. C. above the bed temperature.

  3. Constraining a Distributed Hydrologic Model Using Process Constraints derived from a Catchment Perceptual Model

    NASA Astrophysics Data System (ADS)

    Hutton, Christopher; Wagener, Thorsten; Freer, Jim; Han, Dawei; Duffy, Chris; Musuuza, Jude; Zhang, Jun

    2015-04-01

    The increased availability of spatial datasets and hydrological monitoring techniques improves the potential to apply distributed hydrologic models robustly to simulate catchment systems. However, distributed catchment modelling remains problematic for several reasons, including the miss-match between the scale of process equations and observations, and the scale at which equations (and parameters) are applied at the model grid resolution. A key problem is that when equations are solved over a distributed grid of the catchment system, models contain a considerable number of distributed parameters, and therefore degrees of freedom, that need to be constrained through calibration. Often computational limitations alone prohibit a full search of the multidimensional parameter space. However, even when possible, insufficient data results in model parameter and/or structural equifinality. Calibration approaches therefore attempt to reduce the dimensions of parameter space to constrain model behaviour, typically by fixing, lumping or relating model parameters in some way when calibrating the model to time-series of response data. An alternative approach to help reduce the space of feasible models has been applied to lumped and semi-distributed models, where additional, often semi-qualitative information is used to constrain the internal states and fluxes of the model, which in turn help to identify feasible sets of model structures and parameters. Such process constraints have not been widely applied to distributed hydrological models, despite the fact that distributed models make more predictions of distributed states and fluxes that can potentially be constrained. This paper presents a methodology for deriving process and parameter constraints through development of a perceptual model for a given catchment system, which can then be applied in distributed model calibration and sensitivity analysis to constrain feasible parameter and model structural space. We argue that

  4. Perception in the absence of attention: perceptual processing in the Roelofs effect during inattentional blindness.

    PubMed

    Lathrop, William B; Bridgeman, Bruce; Tseng, Philip

    2011-01-01

    We present two experiments that examine sensory processing during conditions of inattentional blindness. A large rectangular frame that normally induces a Roelofs effect can go unreported due to inattentional blindness. Even when participants fail to report the frame, they mislocalize an attended target in a way consistent with having processed the frame. A more demanding visuospatial distractor task can increase inattentional blindness during conditions of divided attention, but has no effect on the spatial mislocalization illusion. Our results support theories that postulate a significant amount of perceptual processing in the absence of attention. PMID:22208130

  5. Effects of linguistic experience on early levels of perceptual tone processing

    NASA Astrophysics Data System (ADS)

    Huang, Tsan; Johnson, Keith

    2005-04-01

    This study investigated the phenomenon of language-specificity in Mandarin Chinese tone perception. The main question was whether linguistic experience affects the earliest levels of perceptual processing of tones. Chinese and American English listeners participated in four perception experiments, which involved short inter-stimulus intervals (300 ms or 100 ms) and an AX discrimination or AX degree-of-difference rating task. Three experiments used natural speech monosyllabic tone stimuli and one experiment used time-varying sinusoidal simulations of Mandarin tones. AE listeners showed psychoacoustic listening in all experiments, paying much attention to onset and offset pitch. Chinese listeners showed language-specific patterns in all experiments to various degrees, where tonal neutralization rules reduced perceptual distance between two otherwise contrastive tones for Chinese listeners. Since these experiments employed procedures hypothesized to tap the auditory trace mode (Pisoni, Percept. Psychophys. 13, 253-260 (1973)], language-specificity found in this study seems to support the proposal of an auditory cortical map [Guenther et al., J. Acoust. Soc. Am. 23, 213-221 (1999)]. But the model needs refining to account for different degrees of language-specificity, which are better handled by Johnsons (2004, TLS03:26-41) lexical distance model, although the latter model is too rigid in assuming that linguistic experience does not affect low-level perceptual tasks such as AX discrimination with short ISIs.

  6. Blocking serotonin but not dopamine reuptake alters neural processing during perceptual decision making.

    PubMed

    Costa, Vincent D; Kakalios, Laura C; Averbeck, Bruno B

    2016-10-01

    Dopamine and serotonin have opponent interactions on aspects of impulsivity. Therefore we wanted to test the hypothesis that dopamine and serotonin would have opposing effects on speed-accuracy trade offs in a perceptual decision making task. Unlike other behavioral measures of impulsivity, perceptual decision making allows us to determine whether decreasing premature responses, often interpreted as decreased impulsivity, corresponds to increased behavioral performance. We administered GBR-12909 (a dopamine transporter blocker), escitalopram (a serotonin transporter blocker), or saline in separate sessions to 3 rhesus macaques. We found that animals had slower reaction times (RTs) on escitalopram than on GBR-12909 or saline. However, they were also least accurate on escitalopram. Animals were faster, although nonsignificantly, on GBR than saline and had equivalent accuracy. Administration of GBR-12909 did cause animals to be faster in error trials than correct trials. Therefore, from the point of view of RTs the animals were less impulsive on escitalopram. However, the decreased accuracy of the monkeys shows that they were not able to make use of their slower response times to make more accurate decisions. Therefore, impulsivity was reduced on escitalopram, but at the expense of a slower information-processing rate in the perceptual inference task. (PsycINFO Database Record

  7. Blocking serotonin but not dopamine reuptake alters neural processing during perceptual decision making.

    PubMed

    Costa, Vincent D; Kakalios, Laura C; Averbeck, Bruno B

    2016-10-01

    Dopamine and serotonin have opponent interactions on aspects of impulsivity. Therefore we wanted to test the hypothesis that dopamine and serotonin would have opposing effects on speed-accuracy trade offs in a perceptual decision making task. Unlike other behavioral measures of impulsivity, perceptual decision making allows us to determine whether decreasing premature responses, often interpreted as decreased impulsivity, corresponds to increased behavioral performance. We administered GBR-12909 (a dopamine transporter blocker), escitalopram (a serotonin transporter blocker), or saline in separate sessions to 3 rhesus macaques. We found that animals had slower reaction times (RTs) on escitalopram than on GBR-12909 or saline. However, they were also least accurate on escitalopram. Animals were faster, although nonsignificantly, on GBR than saline and had equivalent accuracy. Administration of GBR-12909 did cause animals to be faster in error trials than correct trials. Therefore, from the point of view of RTs the animals were less impulsive on escitalopram. However, the decreased accuracy of the monkeys shows that they were not able to make use of their slower response times to make more accurate decisions. Therefore, impulsivity was reduced on escitalopram, but at the expense of a slower information-processing rate in the perceptual inference task. (PsycINFO Database Record PMID:27513807

  8. Blocking serotonin but not dopamine reuptake alters neural processing during perceptual decision making

    PubMed Central

    Costa, Vincent D.; Kakalios, Laura; Averbeck, Bruno B.

    2016-01-01

    Dopamine and serotonin have opponent interactions on aspects of impulsivity. Therefore we wanted to test the hypothesis that dopamine and serotonin would have opposing effects on speed-accuracy trade-offs in a perceptual decision making task. Unlike other behavioral measures of impulsivity, perceptual decision making allows us to determine whether decreasing premature responses, often interpreted as decreased impulsivity, corresponds to increased behavioral performance. We administered GBR-12909 (a dopamine transporter blocker), escitalopram (a serotonin transporter blocker) or saline in separate sessions to three rhesus macaques. We found that animals had slower reaction times on escitalopram than on GBR-12909 or saline. However, they were also least accurate on escitalopram. Animals were faster, although non-significantly, on GBR than saline and had equivalent accuracy. Administration of GBR-12909 did cause animals to be faster in error trials than correct trials. Therefore, from the point of view of reaction times the animals were less impulsive on escitalopram. However, the decreased accuracy shows that they were not able to make use of the slower response time to make more accurate decisions. Therefore, impulsivity was reduced on escitalopram, but at the expense of information processing rate in the perceptual inference task. PMID:27513807

  9. Transfer-appropriate processing in recognition memory: perceptual and conceptual effects on recognition memory depend on task demands.

    PubMed

    Parks, Colleen M

    2013-07-01

    Research examining the importance of surface-level information to familiarity in recognition memory tasks is mixed: Sometimes it affects recognition and sometimes it does not. One potential explanation of the inconsistent findings comes from the ideas of dual process theory of recognition and the transfer-appropriate processing framework, which suggest that the extent to which perceptual fluency matters on a recognition test depends in large part on the task demands. A test that recruits perceptual processing for discrimination should show greater perceptual effects and smaller conceptual effects than standard recognition, similar to the pattern of effects found in perceptual implicit memory tasks. This idea was tested in the current experiment by crossing a levels of processing manipulation with a modality manipulation on a series of recognition tests that ranged from conceptual (standard recognition) to very perceptually demanding (a speeded recognition test with degraded stimuli). Results showed that the levels of processing effect decreased and the effect of modality increased when tests were made perceptually demanding. These results support the idea that surface-level features influence performance on recognition tests when they are made salient by the task demands.

  10. Disabled vs nondisabled readers: perceptual vs higher-order processing of one vs three letters.

    PubMed

    Allegretti, C L; Puglisi, J T

    1986-10-01

    12 disabled and 12 nondisabled readers (mean age, 11 yr.) were compared on a letter-search task which separated perceptual processing from higher-order processing. Participants were presented a first stimulus (for 200 msec. to minimize eye movements) followed by a second stimulus immediately to estimate the amount of information initially perceived or after a 3000-msec. interval to examine information more permanently stored. Participants were required to decide whether any letter present in the first stimulus was also present in the second. Two processing loads (1 and 3 letters) were examined. Disabled readers showed more pronounced deficits when they were given very little time to process information or more information to process.

  11. The Perceptual Cues that Reshape Expert Reasoning

    PubMed Central

    Harré, Michael; Bossomaier, Terry; Snyder, Allan

    2012-01-01

    The earliest stages in our perception of the world have a subtle but powerful influence on later thought processes; they provide the contextual cues within which our thoughts are framed and they adapt to many different environments throughout our lives. Understanding the changes in these cues is crucial to understanding how our perceptual ability develops, but these changes are often difficult to quantify in sufficiently complex tasks where objective measures of development are available. Here we simulate perceptual learning using neural networks and demonstrate fundamental changes in these cues as a function of skill. These cues are cognitively grouped together to form perceptual templates that enable rapid ‘whole scene' categorisation of complex stimuli. Such categories reduce the computational load on our capacity limited thought processes, they inform our higher cognitive processes and they suggest a framework of perceptual pre-processing that captures the central role of perception in expertise. PMID:22792435

  12. The perceptual cues that reshape expert reasoning.

    PubMed

    Harré, Michael; Bossomaier, Terry; Snyder, Allan

    2012-01-01

    The earliest stages in our perception of the world have a subtle but powerful influence on later thought processes; they provide the contextual cues within which our thoughts are framed and they adapt to many different environments throughout our lives. Understanding the changes in these cues is crucial to understanding how our perceptual ability develops, but these changes are often difficult to quantify in sufficiently complex tasks where objective measures of development are available. Here we simulate perceptual learning using neural networks and demonstrate fundamental changes in these cues as a function of skill. These cues are cognitively grouped together to form perceptual templates that enable rapid 'whole scene' categorisation of complex stimuli. Such categories reduce the computational load on our capacity limited thought processes, they inform our higher cognitive processes and they suggest a framework of perceptual pre-processing that captures the central role of perception in expertise. PMID:22792435

  13. A dynamical framework to relate perceptual variability with multisensory information processing

    PubMed Central

    Thakur, Bhumika; Mukherjee, Abhishek; Sen, Abhijit; Banerjee, Arpan

    2016-01-01

    Multisensory processing involves participation of individual sensory streams, e.g., vision, audition to facilitate perception of environmental stimuli. An experimental realization of the underlying complexity is captured by the “McGurk-effect”- incongruent auditory and visual vocalization stimuli eliciting perception of illusory speech sounds. Further studies have established that time-delay between onset of auditory and visual signals (AV lag) and perturbations in the unisensory streams are key variables that modulate perception. However, as of now only few quantitative theoretical frameworks have been proposed to understand the interplay among these psychophysical variables or the neural systems level interactions that govern perceptual variability. Here, we propose a dynamic systems model consisting of the basic ingredients of any multisensory processing, two unisensory and one multisensory sub-system (nodes) as reported by several researchers. The nodes are connected such that biophysically inspired coupling parameters and time delays become key parameters of this network. We observed that zero AV lag results in maximum synchronization of constituent nodes and the degree of synchronization decreases when we have non-zero lags. The attractor states of this network can thus be interpreted as the facilitator for stabilizing specific perceptual experience. Thereby, the dynamic model presents a quantitative framework for understanding multisensory information processing. PMID:27502974

  14. A dynamical framework to relate perceptual variability with multisensory information processing.

    PubMed

    Thakur, Bhumika; Mukherjee, Abhishek; Sen, Abhijit; Banerjee, Arpan

    2016-01-01

    Multisensory processing involves participation of individual sensory streams, e.g., vision, audition to facilitate perception of environmental stimuli. An experimental realization of the underlying complexity is captured by the "McGurk-effect"- incongruent auditory and visual vocalization stimuli eliciting perception of illusory speech sounds. Further studies have established that time-delay between onset of auditory and visual signals (AV lag) and perturbations in the unisensory streams are key variables that modulate perception. However, as of now only few quantitative theoretical frameworks have been proposed to understand the interplay among these psychophysical variables or the neural systems level interactions that govern perceptual variability. Here, we propose a dynamic systems model consisting of the basic ingredients of any multisensory processing, two unisensory and one multisensory sub-system (nodes) as reported by several researchers. The nodes are connected such that biophysically inspired coupling parameters and time delays become key parameters of this network. We observed that zero AV lag results in maximum synchronization of constituent nodes and the degree of synchronization decreases when we have non-zero lags. The attractor states of this network can thus be interpreted as the facilitator for stabilizing specific perceptual experience. Thereby, the dynamic model presents a quantitative framework for understanding multisensory information processing. PMID:27502974

  15. Susceptibility to a multisensory speech illusion in older persons is driven by perceptual processes

    PubMed Central

    Setti, Annalisa; Burke, Kate E.; Kenny, RoseAnne; Newell, Fiona N.

    2013-01-01

    Recent studies suggest that multisensory integration is enhanced in older adults but it is not known whether this enhancement is solely driven by perceptual processes or affected by cognitive processes. Using the “McGurk illusion,” in Experiment 1 we found that audio-visual integration of incongruent audio-visual words was higher in older adults than in younger adults, although the recognition of either audio- or visual-only presented words was the same across groups. In Experiment 2 we tested recall of sentences within which an incongruent audio-visual speech word was embedded. The overall semantic meaning of the sentence was compatible with either one of the unisensory components of the target word and/or with the illusory percept. Older participants recalled more illusory audio-visual words in sentences than younger adults, however, there was no differential effect of word compatibility on recall for the two groups. Our findings suggest that the relatively high susceptibility to the audio-visual speech illusion in older participants is due more to perceptual than cognitive processing. PMID:24027544

  16. Modelling social interaction as perceptual crossing: an investigation into the dynamics of the interaction process

    NASA Astrophysics Data System (ADS)

    Froese, Tom; Di Paolo, Ezequiel A.

    2010-03-01

    This paper continues efforts to establish a mutually informative dialogue between psychology and evolutionary robotics in order to investigate the dynamics of social interaction. We replicate a recent simulation model of a minimalist experiment in perceptual crossing and confirm the results with significantly simpler artificial agents. A series of psycho-physical tests of their behaviour informs a hypothetical circuit model of their internal operation. However, a detailed study of the actual internal dynamics reveals this circuit model to be unfounded, thereby offering a tale of caution for those hypothesising about sub-personal processes in terms of behavioural observations. In particular, it is shown that the behaviour of the agents largely emerges out of the interaction process itself rather than being an individual achievement alone. We also extend the original simulation model in two novel directions in order to test further the extent to which perceptual crossing between agents can self-organise in a robust manner. These modelling results suggest new hypotheses that can become the basis for further psychological experiments.

  17. Automatic perceptual simulation of first language meanings during second language sentence processing in bilinguals.

    PubMed

    Vukovic, Nikola; Williams, John N

    2014-01-01

    Research supports the claim that, when understanding language, people perform mental simulation using those parts of the brain which support sensation, action, and emotion. A major criticism of the findings quoted as evidence for embodied simulation, however, is that they could be a result of conscious image generation strategies. Here we exploit the well-known fact that bilinguals routinely and automatically activate both their languages during comprehension to test whether this automatic process is, in turn, modulated by embodied simulatory processes. Dutch participants heard English sentences containing interlingual homophones and implying specific distance relations, and had to subsequently respond to pictures of objects matching or mismatching this implied distance. Participants were significantly slower to reject critical items when their perceptual features matched said distance relationship. These results suggest that bilinguals not only activate task-irrelevant meanings of interlingual homophones, but also automatically simulate these meanings in a detailed perceptual fashion. Our study supports the claim that embodied simulation is not due to participants' conscious strategies, but is an automatic component of meaning construction.

  18. Two components in IOR: evidence for response bias and perceptual processing delays using the SAT methodology.

    PubMed

    Zhao, Yuanyuan; Heinke, Dietmar; Ivanoff, Jason; Klein, Raymond M; Humphreys, Glyn W

    2011-10-01

    Inhibition of return (IOR) occurs when reaction times (RTs) are slowed to respond to a target that appears at a previously attended location. We used the speed-accuracy trade-off (SAT) procedure to obtain conjoint measures of IOR on sensitivity and processing speed by presenting targets at cued and uncued locations. The results showed that IOR is associated with both delays in processing speed and shifts in response criterion. When the target was briefly presented, the results supported a criterion shift account of IOR. However, when the target was presented until response, the evidence indicated that, in addition to a response bias effect, there was an increase in the minimal time required for information about the target to accumulate above chance level. A hybrid account of IOR is suggested that describes effects on both response bias and perceptual processing. PMID:21789695

  19. Electrophysiological correlates of the composite face illusion: disentangling perceptual and decisional components of holistic face processing in the human brain.

    PubMed

    Kuefner, Dana; Jacques, Corentin; Prieto, Esther Alonso; Rossion, Bruno

    2010-12-01

    When the bottom halves of two faces differ, people's behavioral judgment of the identical top halves of those faces is impaired: they report that the top halves are different, and/or take more time than usual to provide a response. This behavioral measure is known as the composite face effect (CFE) and has traditionally been taken as evidence that faces are perceived holistically. Recently, however, it has been claimed that this effect is driven almost entirely by decisional, rather than perceptual, factors (Richler, Gauthier, Wenger, & Palmeri, 2008). To disentangle the contribution of perceptual and decisional brain processes, we aimed to obtain an event-related potential (ERP) measure of the CFE at a stage of face encoding (Jacques & Rossion, 2009) in the absence of a behavioral CFE effect. Sixteen participants performed a go/no-go task in an oddball paradigm, lifting a finger of their right or left hand when the top half of a face changed identity. This change of identity of the top of the face was associated with an increased ERP signal on occipito-temporal electrode sites at the N170 face-sensitive component (∼160 ms), the later decisional P3b component, and the lateralized readiness potential (LRP) starting at ∼350 ms. The N170 effect was observed equally early when only the unattended bottom part of the face changed, indicating that an identity change was perceived across the whole face in this condition. Importantly, there was no behavioral response bias for the bottom change trials, and no evidence of decisional biases from electrophysiological data (no P3b and LRP deflection in no-go trials). These data show that an early CFE can be measured in ERPs in the absence of any decisional response bias, indicating that the CFE reflects primarily the visual perception of the whole face.

  20. The processing of biologically plausible and implausible forms in American Sign Language: evidence for perceptual tuning

    PubMed Central

    Almeida, Diogo; Poeppel, David; Corina, David

    2016-01-01

    ABSTRACT The human auditory system distinguishes speech-like information from general auditory signals in a remarkably fast and efficient way. Combining psychophysics and neurophysiology (MEG), we demonstrate a similar result for the processing of visual information used for language communication in users of sign languages. We demonstrate that the earliest visual cortical responses in deaf signers viewing American Sign Language signs show specific modulations to violations of anatomic constraints that would make the sign either possible or impossible to articulate. These neural data are accompanied with a significantly increased perceptual sensitivity to the anatomical incongruity. The differential effects in the early visual evoked potentials arguably reflect an expectation-driven assessment of somatic representational integrity, suggesting that language experience and/or auditory deprivation may shape the neuronal mechanisms underlying the analysis of complex human form. The data demonstrate that the perceptual tuning that underlies the discrimination of language and non-language information is not limited to spoken languages but extends to languages expressed in the visual modality. PMID:27135041

  1. Perceptual Learning With Tactile Stimuli in Rats: Changes in the Processing of a Dimension

    PubMed Central

    2016-01-01

    Four experiments with male rats investigated perceptual learning involving a tactile dimension (A, B, C, D, E), where A denotes 1 end of the continuum (e.g., a rough floor) and E the other (e.g., a smooth floor). In Experiment 1, rats given preexposure to A and E learned an appetitive discrimination between them more readily than those not given preexposure. Experiment 2a showed that rats preexposed to B and D acquired a discrimination between A and E more readily than those preexposed to A and E; and in Experiment 2b the same preexposure treatments had no effect on the acquisition of a discrimination between B and D. In Experiments 3a and 3b, rats given preexposure to C learned a discrimination between A and E more readily than those not given preexposure. Experiment 4 demonstrated that preexposure to a texture (e.g., B) that was adjacent to the to-be-discriminated textures (e.g., C and E) facilitated a discrimination between them relative to preexposure to their midpoint (D). These novel perceptual learning effects are interpreted as reflecting a redistribution of processing between the notional elements of the texture dimension. PMID:27379718

  2. Perceptual learning with tactile stimuli in rats: Changes in the processing of a dimension.

    PubMed

    Montuori, Luke M; Honey, R C

    2016-07-01

    Four experiments with male rats investigated perceptual learning involving a tactile dimension (A, B, C, D, E), where A denotes 1 end of the continuum (e.g., a rough floor) and E the other (e.g., a smooth floor). In Experiment 1, rats given preexposure to A and E learned an appetitive discrimination between them more readily than those not given preexposure. Experiment 2a showed that rats preexposed to B and D acquired a discrimination between A and E more readily than those preexposed to A and E; and in Experiment 2b the same preexposure treatments had no effect on the acquisition of a discrimination between B and D. In Experiments 3a and 3b, rats given preexposure to C learned a discrimination between A and E more readily than those not given preexposure. Experiment 4 demonstrated that preexposure to a texture (e.g., B) that was adjacent to the to-be-discriminated textures (e.g., C and E) facilitated a discrimination between them relative to preexposure to their midpoint (D). These novel perceptual learning effects are interpreted as reflecting a redistribution of processing between the notional elements of the texture dimension. (PsycINFO Database Record PMID:27379718

  3. Two-stage coal liquefaction process

    DOEpatents

    Skinner, Ronald W.; Tao, John C.; Znaimer, Samuel

    1985-01-01

    An improved SRC-I two-stage coal liquefaction process which improves the product slate is provided. Substantially all of the net yield of 650.degree.-850.degree. F. heavy distillate from the LC-Finer is combined with the SRC process solvent, substantially all of the net 400.degree.-650.degree. F. middle distillate from the SRC section is combined with the hydrocracker solvent in the LC-Finer, and the initial boiling point of the SRC process solvent is increased sufficiently high to produce a net yield of 650.degree.-850.degree. F. heavy distillate of zero for the two-stage liquefaction process.

  4. The Influence of Perceptual and Semantic Categorization on Inhibitory Processing as Measured by the N2-P3 Response

    ERIC Educational Resources Information Center

    Maguire, Mandy J.; Brier, Matthew R.; Moore, Patricia S.; Ferree, Thomas C.; Ray, Dylan; Mostofsky, Stewart; Hart, John, Jr.; Kraut, Michael A.

    2009-01-01

    In daily activities, humans must attend and respond to a range of important items and inhibit and not respond to unimportant distractions. Our current understanding of these processes is largely based on perceptually simple stimuli. This study investigates the interaction of conceptual-semantic categorization and inhibitory processing using Event…

  5. Effects of Language Comprehension on Visual Processing--MEG Dissociates Early Perceptual and Late N400 Effects

    ERIC Educational Resources Information Center

    Hirschfeld, Gerrit; Zwitserlood, Pienie; Dobel, Christian

    2011-01-01

    We investigated whether and when information conveyed by spoken language impacts on the processing of visually presented objects. In contrast to traditional views, grounded-cognition posits direct links between language comprehension and perceptual processing. We used a magnetoencephalographic cross-modal priming paradigm to disentangle these…

  6. A predictive processing theory of sensorimotor contingencies: Explaining the puzzle of perceptual presence and its absence in synesthesia.

    PubMed

    Seth, Anil K

    2014-01-01

    Normal perception involves experiencing objects within perceptual scenes as real, as existing in the world. This property of "perceptual presence" has motivated "sensorimotor theories" which understand perception to involve the mastery of sensorimotor contingencies. However, the mechanistic basis of sensorimotor contingencies and their mastery has remained unclear. Sensorimotor theory also struggles to explain instances of perception, such as synesthesia, that appear to lack perceptual presence and for which relevant sensorimotor contingencies are difficult to identify. On alternative "predictive processing" theories, perceptual content emerges from probabilistic inference on the external causes of sensory signals, however, this view has addressed neither the problem of perceptual presence nor synesthesia. Here, I describe a theory of predictive perception of sensorimotor contingencies which (1) accounts for perceptual presence in normal perception, as well as its absence in synesthesia, and (2) operationalizes the notion of sensorimotor contingencies and their mastery. The core idea is that generative models underlying perception incorporate explicitly counterfactual elements related to how sensory inputs would change on the basis of a broad repertoire of possible actions, even if those actions are not performed. These "counterfactually-rich" generative models encode sensorimotor contingencies related to repertoires of sensorimotor dependencies, with counterfactual richness determining the degree of perceptual presence associated with a stimulus. While the generative models underlying normal perception are typically counterfactually rich (reflecting a large repertoire of possible sensorimotor dependencies), those underlying synesthetic concurrents are hypothesized to be counterfactually poor. In addition to accounting for the phenomenology of synesthesia, the theory naturally accommodates phenomenological differences between a range of experiential states

  7. A predictive processing theory of sensorimotor contingencies: Explaining the puzzle of perceptual presence and its absence in synesthesia.

    PubMed

    Seth, Anil K

    2014-01-01

    Normal perception involves experiencing objects within perceptual scenes as real, as existing in the world. This property of "perceptual presence" has motivated "sensorimotor theories" which understand perception to involve the mastery of sensorimotor contingencies. However, the mechanistic basis of sensorimotor contingencies and their mastery has remained unclear. Sensorimotor theory also struggles to explain instances of perception, such as synesthesia, that appear to lack perceptual presence and for which relevant sensorimotor contingencies are difficult to identify. On alternative "predictive processing" theories, perceptual content emerges from probabilistic inference on the external causes of sensory signals, however, this view has addressed neither the problem of perceptual presence nor synesthesia. Here, I describe a theory of predictive perception of sensorimotor contingencies which (1) accounts for perceptual presence in normal perception, as well as its absence in synesthesia, and (2) operationalizes the notion of sensorimotor contingencies and their mastery. The core idea is that generative models underlying perception incorporate explicitly counterfactual elements related to how sensory inputs would change on the basis of a broad repertoire of possible actions, even if those actions are not performed. These "counterfactually-rich" generative models encode sensorimotor contingencies related to repertoires of sensorimotor dependencies, with counterfactual richness determining the degree of perceptual presence associated with a stimulus. While the generative models underlying normal perception are typically counterfactually rich (reflecting a large repertoire of possible sensorimotor dependencies), those underlying synesthetic concurrents are hypothesized to be counterfactually poor. In addition to accounting for the phenomenology of synesthesia, the theory naturally accommodates phenomenological differences between a range of experiential states

  8. Perceptual decision processes flexibly adapt to avoid change-of-mind motor costs.

    PubMed

    Moher, Jeff; Song, Joo-Hyun

    2014-07-01

    The motor system is tightly linked with perception and cognition. Recent studies have shown that even anticipated biophysical action costs associated with competing response options can be incorporated into decision-making processes. As a result, choices associated with high energy costs are less likely to be selected. However, some action costs may be harder to predict. For example, a person choosing among apples at a grocery store may change his or her mind suddenly about which apple to put into the cart. This change of mind may be reflected in motor output as the initial decision triggers a motor response toward a Granny Smith that is subsequently redirected toward a Red Delicious. In the present study, to examine how motor costs associated with changes of mind affect perceptual decision making, participants performed a difficult random dot–motion discrimination task in which they had to indicate the direction of motion by reaching to one of two response options. Although each response box was always equidistant from the starting position, the physical distance between the two response options was varied. We found that when the boxes were far apart from one another, and thus changes of mind incurred greater redirection motor costs, change-of-mind frequency decreased while latency to initiate movement increased. This occurred even when response box distance varied randomly from trial to trial and was cued only 1 s before each trial began. Thus, we demonstrated that observers can dynamically adjust perceptual decision-making processes to avoid high motor costs incurred by a change of mind.

  9. Disruption of Broca's Area Alters Higher-order Chunking Processing during Perceptual Sequence Learning.

    PubMed

    Alamia, Andrea; Solopchuk, Oleg; D'Ausilio, Alessandro; Van Bever, Violette; Fadiga, Luciano; Olivier, Etienne; Zénon, Alexandre

    2016-03-01

    Because Broca's area is known to be involved in many cognitive functions, including language, music, and action processing, several attempts have been made to propose a unifying theory of its role that emphasizes a possible contribution to syntactic processing. Recently, we have postulated that Broca's area might be involved in higher-order chunk processing during implicit learning of a motor sequence. Chunking is an information-processing mechanism that consists of grouping consecutive items in a sequence and is likely to be involved in all of the aforementioned cognitive processes. Demonstrating a contribution of Broca's area to chunking during the learning of a nonmotor sequence that does not involve language could shed new light on its function. To address this issue, we used offline MRI-guided TMS in healthy volunteers to disrupt the activity of either the posterior part of Broca's area (left Brodmann's area [BA] 44) or a control site just before participants learned a perceptual sequence structured in distinct hierarchical levels. We found that disruption of the left BA 44 increased the processing time of stimuli representing the boundaries of higher-order chunks and modified the chunking strategy. The current results highlight the possible role of the left BA 44 in building up effector-independent representations of higher-order events in structured sequences. This might clarify the contribution of Broca's area in processing hierarchical structures, a key mechanism in many cognitive functions, such as language and composite actions. PMID:26765778

  10. Holistic processing as a hallmark of perceptual expertise for nonface categories including Chinese characters.

    PubMed

    Wong, Alan C-N; Bukach, Cindy M; Hsiao, Janet; Greenspon, Emma; Ahern, Emily; Duan, Yiran; Lui, Kelvin F H

    2012-12-06

    Holistic processing has been associated with perceptual expertise in different domains involving faces, cars, fingerprints, musical notes, English words, etc. Curiously Chinese characters are regarded as an exception, as indicated by reduced holistic processing found for experts with the Chinese writing system as compared with novices. We revisit the issue and examine one type of holistic processing, the obligatory attention to all parts of an object, using the composite paradigm from face perception literature. Chinese readers (experts) and non-Chinese readers (novices) matched the target halves of two characters while ignoring the irrelevant halves. We introduced differential response deadlines for experts and novices in order to match their performance level and to avoid ceiling performance for experts. Both experts and novices showed holistic processing, irrespective of the character structure (left-right or top-bottom) or presentation sequence (sequential or simultaneous matching). Experts' holistic processing also showed some sensitivity to the amount of experience with the characters, as it was larger for characters than noncharacters in some situations. Novices, however, did not show a systematic difference, suggesting that their effects were more related to their inefficient decomposition of a novel, complex pattern into parts. The current results, together with other recent findings of holistic processing for English words and musical notes, indicate that the development of holistic processing is not restricted to faces and objects. Instead it may be a general marker of expertise across a wider domain of visual discrimination than previously thought, including alphabetic and nonalphabetic writing systems.

  11. Holistic processing as a hallmark of perceptual expertise for nonface categories including Chinese characters.

    PubMed

    Wong, Alan C-N; Bukach, Cindy M; Hsiao, Janet; Greenspon, Emma; Ahern, Emily; Duan, Yiran; Lui, Kelvin F H

    2012-01-01

    Holistic processing has been associated with perceptual expertise in different domains involving faces, cars, fingerprints, musical notes, English words, etc. Curiously Chinese characters are regarded as an exception, as indicated by reduced holistic processing found for experts with the Chinese writing system as compared with novices. We revisit the issue and examine one type of holistic processing, the obligatory attention to all parts of an object, using the composite paradigm from face perception literature. Chinese readers (experts) and non-Chinese readers (novices) matched the target halves of two characters while ignoring the irrelevant halves. We introduced differential response deadlines for experts and novices in order to match their performance level and to avoid ceiling performance for experts. Both experts and novices showed holistic processing, irrespective of the character structure (left-right or top-bottom) or presentation sequence (sequential or simultaneous matching). Experts' holistic processing also showed some sensitivity to the amount of experience with the characters, as it was larger for characters than noncharacters in some situations. Novices, however, did not show a systematic difference, suggesting that their effects were more related to their inefficient decomposition of a novel, complex pattern into parts. The current results, together with other recent findings of holistic processing for English words and musical notes, indicate that the development of holistic processing is not restricted to faces and objects. Instead it may be a general marker of expertise across a wider domain of visual discrimination than previously thought, including alphabetic and nonalphabetic writing systems. PMID:23220578

  12. Neural representations of confidence emerge from the process of decision formation during perceptual choices.

    PubMed

    Gherman, Sabina; Philiastides, Marios G

    2015-02-01

    Choice confidence represents the degree of belief that one's actions are likely to be correct or rewarding and plays a critical role in optimizing our decisions. Despite progress in understanding the neurobiology of human perceptual decision-making, little is known about the representation of confidence. Importantly, it remains unclear whether confidence forms an integral part of the decision process itself or represents a purely post-decisional signal. To address this issue we employed a paradigm whereby on some trials, prior to indicating their decision, participants could opt-out of the task for a small but certain reward. This manipulation captured participants' confidence on individual trials and allowed us to discriminate between electroencephalographic signals associated with certain-vs.-uncertain trials. Discrimination increased gradually and peaked well before participants indicated their choice. These signals exhibited a temporal profile consistent with a process of evidence accumulation, culminating at time of peak discrimination. Moreover, trial-by-trial fluctuations in the accumulation rate of nominally identical stimuli were predictive of participants' likelihood to opt-out of the task, suggesting that confidence emerges from the decision process itself and is computed continuously as the process unfolds. Correspondingly, source reconstruction placed these signals in regions previously implicated in decision making, within the prefrontal and parietal cortices. Crucially, control analyses ensured that these results could not be explained by stimulus difficulty, lapses in attention or decision accuracy.

  13. Handshape monitoring: Evaluation of linguistic and perceptual factors in the processing of American Sign Language

    PubMed Central

    Grosvald, Michael; Lachaud, Christian; Corina, David

    2011-01-01

    We investigated the relevance of linguistic and perceptual factors to sign processing by comparing hearing individuals and deaf signers as they performed a handshape monitoring task, a sign-language analogue to the phoneme-monitoring paradigms used in many spoken-language studies. Each subject saw a series of brief video clips, each of which showed either an ASL sign or a phonologically possible but non-lexical “non-sign,” and responded when the viewed action was formed with a particular handshape. Stimuli varied with respect to the factors of Lexicality, handshape Markedness (Battison, 1978), and Type, defined according to whether the action is performed with one or two hands and for two-handed stimuli, whether or not the action is symmetrical. Deaf signers performed faster and more accurately than hearing non-signers, and effects related to handshape Markedness and stimulus Type were observed in both groups. However, no effects or interactions related to Lexicality were seen. A further analysis restricted to the deaf group indicated that these results were not dependent upon subjects' age of acquisition of ASL. This work provides new insights into the processes by which the handshape component of sign forms is recognized in a sign language, the role of language experience, and the extent to which these processes may or may not be considered specifically linguistic. PMID:22822282

  14. Exploring perceptual processing of ASL and human actions: effects of inversion and repetition priming.

    PubMed

    Corina, David P; Grosvald, Michael

    2012-03-01

    In this paper, we compare responses of deaf signers and hearing non-signers engaged in a categorization task of signs and non-linguistic human actions. We examine the time it takes to make such categorizations under conditions of 180° stimulus inversion and as a function of repetition priming, in an effort to understand whether the processing of sign language forms draws upon special processing mechanisms or makes use of mechanisms used in recognition of non-linguistic human actions. Our data show that deaf signers were much faster in the categorization of both linguistic and non-linguistic actions, and relative to hearing non-signers, show evidence that they were more sensitive to the configural properties of signs. Our study suggests that sign expertise may lead to modifications of a general-purpose human action recognition system rather than evoking a qualitatively different mode of processing, and supports the contention that signed languages make use of perceptual systems through which humans understand or parse human actions and gestures more generally. PMID:22153323

  15. Exploring perceptual processing of ASL and human actions: Effects of inversion and repetition priming

    PubMed Central

    Corina, David P.; Grosvald, Michael

    2011-01-01

    In this paper, we compare responses of deaf signers and hearing non-signers engaged in a categorization task of signs and non-linguistic human actions. We examine the time it takes to make such categorizations under conditions of 180-degree stimulus inversion and as a function of repetition priming, in an effort to understand whether the processing of sign language forms draws upon special processing mechanisms or makes use of mechanisms used in recognition of non-linguistic human actions. Our data show that deaf signers were much faster in the categorization of both linguistic and non-linguistic actions, and relative to hearing non-signers, show evidence that they were more sensitive to the configural properties of signs. Our study suggests that sign expertise may lead to modifications of a general-purpose human action recognition system rather than evoking a qualitatively different mode of processing, and supports the contention that signed languages make use of perceptual systems through which humans understand or parse human actions and gestures more generally. PMID:22153323

  16. Act quickly, decide later: long-latency visual processing underlies perceptual decisions but not reflexive behavior.

    PubMed

    Jolij, Jacob; Scholte, H Steven; van Gaal, Simon; Hodgson, Timothy L; Lamme, Victor A F

    2011-12-01

    Humans largely guide their behavior by their visual representation of the world. Recent studies have shown that visual information can trigger behavior within 150 msec, suggesting that visually guided responses to external events, in fact, precede conscious awareness of those events. However, is such a view correct? By using a texture discrimination task, we show that the brain relies on long-latency visual processing in order to guide perceptual decisions. Decreasing stimulus saliency leads to selective changes in long-latency visually evoked potential components reflecting scene segmentation. These latency changes are accompanied by almost equal changes in simple RTs and points of subjective simultaneity. Furthermore, we find a strong correlation between individual RTs and the latencies of scene segmentation related components in the visually evoked potentials, showing that the processes underlying these late brain potentials are critical in triggering a response. However, using the same texture stimuli in an antisaccade task, we found that reflexive, but erroneous, prosaccades, but not antisaccades, can be triggered by earlier visual processes. In other words: The brain can act quickly, but decides late. Differences between our study and earlier findings suggesting that action precedes conscious awareness can be explained by assuming that task demands determine whether a fast and unconscious, or a slower and conscious, representation is used to initiate a visually guided response. PMID:21557644

  17. Now or … later: Perceptual data are not immediately forgotten during language processing.

    PubMed

    Bicknell, Klinton; Jaeger, T Florian; Tanenhaus, Michael K

    2016-01-01

    Christiansen & Chater (C&C) propose that language comprehenders must immediately compress perceptual data by "chunking" them into higher-level categories. Effective language understanding, however, requires maintaining perceptual information long enough to integrate it with downstream cues. Indeed, recent results suggest comprehenders do this. Although cognitive systems are undoubtedly limited, frameworks that do not take into account the tasks that these systems evolved to solve risk missing important insights. PMID:27562505

  18. Perceptual grouping does not affect multi-attribute decision making if no processing costs are involved.

    PubMed

    Ettlin, Florence; Bröder, Arndt

    2015-05-01

    Adaptive strategy selection implies that a decision strategy is chosen based on its fit to the task and situation. However, other aspects, such as the way information is presented, can determine information search behavior; especially when the application of certain strategies over others is facilitated. But are such display effects on multi-attribute decisions also at work when the manipulation does not entail differential costs for different decision strategies? Three Mouselab experiments with hidden information and one eye tracking experiment with an open information board revealed that decision behavior is unaffected by purely perceptual manipulations of the display based on Gestalt principles; that is, based on manipulations that induce no noteworthy processing costs for different information search patterns. We discuss our results in the context of previous findings on display effects; specifically, how the combination of these findings and our results reveal the crucial role of differential processing costs for different strategies for the emergence of display effects. This finding describes a boundary condition of the commonly acknowledged influence of information displays and is in line with the ideas of adaptive strategy selection and cost-benefit tradeoffs.

  19. Fusiform Gyrus Dysfunction is Associated with Perceptual Processing Efficiency to Emotional Faces in Adolescent Depression: A Model-Based Approach.

    PubMed

    Ho, Tiffany C; Zhang, Shunan; Sacchet, Matthew D; Weng, Helen; Connolly, Colm G; Henje Blom, Eva; Han, Laura K M; Mobayed, Nisreen O; Yang, Tony T

    2016-01-01

    While the extant literature has focused on major depressive disorder (MDD) as being characterized by abnormalities in processing affective stimuli (e.g., facial expressions), little is known regarding which specific aspects of cognition influence the evaluation of affective stimuli, and what are the underlying neural correlates. To investigate these issues, we assessed 26 adolescents diagnosed with MDD and 37 well-matched healthy controls (HCL) who completed an emotion identification task of dynamically morphing faces during functional magnetic resonance imaging (fMRI). We analyzed the behavioral data using a sequential sampling model of response time (RT) commonly used to elucidate aspects of cognition in binary perceptual decision making tasks: the Linear Ballistic Accumulator (LBA) model. Using a hierarchical Bayesian estimation method, we obtained group-level and individual-level estimates of LBA parameters on the facial emotion identification task. While the MDD and HCL groups did not differ in mean RT, accuracy, or group-level estimates of perceptual processing efficiency (i.e., drift rate parameter of the LBA), the MDD group showed significantly reduced responses in left fusiform gyrus compared to the HCL group during the facial emotion identification task. Furthermore, within the MDD group, fMRI signal in the left fusiform gyrus during affective face processing was significantly associated with greater individual-level estimates of perceptual processing efficiency. Our results therefore suggest that affective processing biases in adolescents with MDD are characterized by greater perceptual processing efficiency of affective visual information in sensory brain regions responsible for the early processing of visual information. The theoretical, methodological, and clinical implications of our results are discussed.

  20. Fusiform Gyrus Dysfunction is Associated with Perceptual Processing Efficiency to Emotional Faces in Adolescent Depression: A Model-Based Approach

    PubMed Central

    Ho, Tiffany C.; Zhang, Shunan; Sacchet, Matthew D.; Weng, Helen; Connolly, Colm G.; Henje Blom, Eva; Han, Laura K. M.; Mobayed, Nisreen O.; Yang, Tony T.

    2016-01-01

    While the extant literature has focused on major depressive disorder (MDD) as being characterized by abnormalities in processing affective stimuli (e.g., facial expressions), little is known regarding which specific aspects of cognition influence the evaluation of affective stimuli, and what are the underlying neural correlates. To investigate these issues, we assessed 26 adolescents diagnosed with MDD and 37 well-matched healthy controls (HCL) who completed an emotion identification task of dynamically morphing faces during functional magnetic resonance imaging (fMRI). We analyzed the behavioral data using a sequential sampling model of response time (RT) commonly used to elucidate aspects of cognition in binary perceptual decision making tasks: the Linear Ballistic Accumulator (LBA) model. Using a hierarchical Bayesian estimation method, we obtained group-level and individual-level estimates of LBA parameters on the facial emotion identification task. While the MDD and HCL groups did not differ in mean RT, accuracy, or group-level estimates of perceptual processing efficiency (i.e., drift rate parameter of the LBA), the MDD group showed significantly reduced responses in left fusiform gyrus compared to the HCL group during the facial emotion identification task. Furthermore, within the MDD group, fMRI signal in the left fusiform gyrus during affective face processing was significantly associated with greater individual-level estimates of perceptual processing efficiency. Our results therefore suggest that affective processing biases in adolescents with MDD are characterized by greater perceptual processing efficiency of affective visual information in sensory brain regions responsible for the early processing of visual information. The theoretical, methodological, and clinical implications of our results are discussed. PMID:26869950

  1. Being selective at the plate: processing dependence between perceptual variables relates to hitting goals and performance.

    PubMed

    Gray, Rob

    2013-08-01

    Performance of a skill that involves acting on a goal object (e.g., a ball to be hit) can influence one's judgment of the size and speed of that object. The present study examined how these action-specific effects are affected when the goal of the actor is varied and they are free to choose between alternative actions. In Experiment 1, expert baseball players were asked to perform three different directional hitting tasks in a batting simulation and make interleaved perceptual judgments about three ball parameters (speed, plate crossing location, and size). Perceived ball size was largest (and perceived speed was slowest) when the ball crossing location was optimal for the particular hitting task the batter was performing (e.g., an "outside" pitch for opposite-field hitting). The magnitude of processing dependency between variables (speed vs. location and size vs. location) was positively correlated with batting performance. In Experiment 2, the action-specific effects observed in Experiment 1 were mimicked by systematically changing the ball diameter in the simulation as a function of plate crossing location. The number of swing initiations was greater when ball size was larger, and batters were more successful in the hitting task for which the larger pitches were optimal (e.g., greater number of pull hits than opposite-field hits when "inside" pitches were larger). These findings suggest attentional accentuation of goal-relevant targets underlies action-related changes in perception and are consistent with an action selection role for these effects.

  2. Brain dynamics of upstream perceptual processes leading to visual object recognition: a high density ERP topographic mapping study.

    PubMed

    Schettino, Antonio; Loeys, Tom; Delplanque, Sylvain; Pourtois, Gilles

    2011-04-01

    Recent studies suggest that visual object recognition is a proactive process through which perceptual evidence accumulates over time before a decision can be made about the object. However, the exact electrophysiological correlates and time-course of this complex process remain unclear. In addition, the potential influence of emotion on this process has not been investigated yet. We recorded high density EEG in healthy adult participants performing a novel perceptual recognition task. For each trial, an initial blurred visual scene was first shown, before the actual content of the stimulus was gradually revealed by progressively adding diagnostic high spatial frequency information. Participants were asked to stop this stimulus sequence as soon as they could correctly perform an animacy judgment task. Behavioral results showed that participants reliably gathered perceptual evidence before recognition. Furthermore, prolonged exploration times were observed for pleasant, relative to either neutral or unpleasant scenes. ERP results showed distinct effects starting at 280 ms post-stimulus onset in distant brain regions during stimulus processing, mainly characterized by: (i) a monotonic accumulation of evidence, involving regions of the posterior cingulate cortex/parahippocampal gyrus, and (ii) true categorical recognition effects in medial frontal regions, including the dorsal anterior cingulate cortex. These findings provide evidence for the early involvement, following stimulus onset, of non-overlapping brain networks during proactive processes eventually leading to visual object recognition.

  3. Brain dynamics of upstream perceptual processes leading to visual object recognition: a high density ERP topographic mapping study.

    PubMed

    Schettino, Antonio; Loeys, Tom; Delplanque, Sylvain; Pourtois, Gilles

    2011-04-01

    Recent studies suggest that visual object recognition is a proactive process through which perceptual evidence accumulates over time before a decision can be made about the object. However, the exact electrophysiological correlates and time-course of this complex process remain unclear. In addition, the potential influence of emotion on this process has not been investigated yet. We recorded high density EEG in healthy adult participants performing a novel perceptual recognition task. For each trial, an initial blurred visual scene was first shown, before the actual content of the stimulus was gradually revealed by progressively adding diagnostic high spatial frequency information. Participants were asked to stop this stimulus sequence as soon as they could correctly perform an animacy judgment task. Behavioral results showed that participants reliably gathered perceptual evidence before recognition. Furthermore, prolonged exploration times were observed for pleasant, relative to either neutral or unpleasant scenes. ERP results showed distinct effects starting at 280 ms post-stimulus onset in distant brain regions during stimulus processing, mainly characterized by: (i) a monotonic accumulation of evidence, involving regions of the posterior cingulate cortex/parahippocampal gyrus, and (ii) true categorical recognition effects in medial frontal regions, including the dorsal anterior cingulate cortex. These findings provide evidence for the early involvement, following stimulus onset, of non-overlapping brain networks during proactive processes eventually leading to visual object recognition. PMID:21237274

  4. Processing of Perceptual Information Is More Robust than Processing of Conceptual Information in Preschool-Age Children: Evidence from Costs of Switching

    ERIC Educational Resources Information Center

    Fisher, Anna V.

    2011-01-01

    Is processing of conceptual information as robust as processing of perceptual information early in development? Existing empirical evidence is insufficient to answer this question. To examine this issue, 3- to 5-year-old children were presented with a flexible categorization task, in which target items (e.g., an open red umbrella) shared category…

  5. Trait anxiety and perceptual load as determinants of emotion processing in a fear conditioning paradigm.

    PubMed

    Fox, Elaine; Yates, Alan; Ashwin, Chris

    2012-04-01

    The impact of trait anxiety and perceptual load on selective attention was examined in a fear conditioning paradigm. A fear-conditioned angry face (CS+), an unconditioned angry face (CS-), or an unconditioned face with a neutral or happy expression were used in distractor interference and attentional probe tasks. In Experiments 1 and 2, participants classified centrally presented letters under two conditions of perceptual load. When perceptual load was high, distractors had no effect on selective attention, even with aversive conditioning. However, when perceptual load was low, strong response interference effects for CS+ face distractors were found for low trait-anxious participants. Across both experiments, this enhanced distractor interference reversed to strong facilitation effects for those reporting high trait anxiety. Thus, high trait-anxious participants were faster, rather than slower, when ignoring CS+ distractors. Using an attentional probe task in Experiment 3, it was found that fear conditioning resulted in strong attentional avoidance in a high trait-anxious group, which contrasted with enhanced vigilance in a low trait-anxious group. These results demonstrate that the impact of fear conditioning on attention is modulated by individual variation in trait anxiety when perceptual load is low. Fear conditioning elicits an avoidance of threat-relevant stimuli in high trait-anxious participants.

  6. Detecting age differences in inhibition processes with a test of perceptual and motor inhibition

    PubMed Central

    Jennings, J. Richard; Mendelson, David N.; Redfern, Mark S.; Nebes, Robert D

    2010-01-01

    We asked whether different forms of inhibition are altered differently by aging using a Motor and Perceptual Inhibition Test (MAPIT) based on Nassauer and Halperin (Nassauer & Halperin, 2003). Ninety-eight individuals participating in studies of balance and attention were separated into younger (mean age 25 years) and older participants (mean age 73). Older participants showed less Perceptual and Motor Inhibition than younger participant with moderation of this effect by gender. The two scores were uncorrelated in the young but significantly correlated in the older group. Overall, the MAPIT appeared to yield reliable measures of two aspects of inhibition that demonstrate a differential impact of age. PMID:21424956

  7. Action-Specific Disruption of Perceptual Confidence

    PubMed Central

    Maniscalco, Brian; Ko, Yoshiaki; Amendi, Namema; Ro, Tony; Lau, Hakwan

    2015-01-01

    Theoretical models of perception assume that confidence is related to the quality or strength of sensory processing. Counter to this intuitive view, we showed in the present research that the motor system also contributes to judgments of perceptual confidence. In two experiments, we used transcranial magnetic stimulation (TMS) to manipulate response-specific representations in the premotor cortex, selectively disrupting postresponse confidence in visual discrimination judgments. Specifically, stimulation of the motor representation associated with the unchosen response reduced confidence in correct responses, thereby reducing metacognitive capacity without changing visual discrimination performance. Effects of TMS on confidence were observed when stimulation was applied both before and after the response occurred, which suggests that confidence depends on late-stage metacognitive processes. These results place constraints on models of perceptual confidence and metacognition by revealing that action-specific information in the premotor cortex contributes to perceptual confidence. PMID:25425059

  8. Being selective at the plate: processing dependence between perceptual variables relates to hitting goals and performance.

    PubMed

    Gray, Rob

    2013-08-01

    Performance of a skill that involves acting on a goal object (e.g., a ball to be hit) can influence one's judgment of the size and speed of that object. The present study examined how these action-specific effects are affected when the goal of the actor is varied and they are free to choose between alternative actions. In Experiment 1, expert baseball players were asked to perform three different directional hitting tasks in a batting simulation and make interleaved perceptual judgments about three ball parameters (speed, plate crossing location, and size). Perceived ball size was largest (and perceived speed was slowest) when the ball crossing location was optimal for the particular hitting task the batter was performing (e.g., an "outside" pitch for opposite-field hitting). The magnitude of processing dependency between variables (speed vs. location and size vs. location) was positively correlated with batting performance. In Experiment 2, the action-specific effects observed in Experiment 1 were mimicked by systematically changing the ball diameter in the simulation as a function of plate crossing location. The number of swing initiations was greater when ball size was larger, and batters were more successful in the hitting task for which the larger pitches were optimal (e.g., greater number of pull hits than opposite-field hits when "inside" pitches were larger). These findings suggest attentional accentuation of goal-relevant targets underlies action-related changes in perception and are consistent with an action selection role for these effects. PMID:23163787

  9. Theory and practice of perceptual video processing in broadcast encoders for cable, IPTV, satellite, and internet distribution

    NASA Astrophysics Data System (ADS)

    McCarthy, S.

    2014-02-01

    This paper describes the theory and application of a perceptually-inspired video processing technology that was recently incorporated into professional video encoders now being used by major cable, IPTV, satellite, and internet video service providers. We will present data that show that this perceptual video processing (PVP) technology can improve video compression efficiency by up to 50% for MPEG-2, H.264, and High Efficiency Video Coding (HEVC). The PVP technology described in this paper works by forming predicted eye-tracking attractor maps that indicate how likely it might be that a free viewing person would look at particular area of an image or video. We will introduce in this paper the novel model and supporting theory used to calculate the eye-tracking attractor maps. We will show how the underlying perceptual model was inspired by electrophysiological studies of the vertebrate retina, and will explain how the model incorporates statistical expectations about natural scenes as well as a novel method for predicting error in signal estimation tasks. Finally, we will describe how the eye-tracking attractor maps are created in real time and used to modify video prior to encoding so that it is more compressible but not noticeably different than the original unmodified video.

  10. Perceptual frames in frequency estimation.

    PubMed

    Zyłowska, Aleksandra; Kossek, Marcin; Wawrzyniak, Małgorzata

    2014-02-01

    This study is an introductory investigation of cognitive frames, focused on perceptual frames divided into information and formal perceptual frames, which were studied based on sub-additivity of frequency estimations. It was postulated that different presentations of a response scale would result in different percentage estimates of time spent watching TV or using the Internet. The results supported the existence of perceptual frames that influence the perception process and indicated that information perceptual frames had a stronger effect than formal frames. The measures made possible the exploration of the operation of perceptual frames and also outlined the relations between heuristics and cognitive frames. PMID:24765715

  11. Gestalt Processing in Autism: Failure to Process Perceptual Relationships and the Implications for Contextual Understanding

    ERIC Educational Resources Information Center

    Brosnan, Mark J.; Scott, Fiona J.; Fox, Simone; Pye, Jackie

    2004-01-01

    Background: Deficits in autism have been characterised as a bias towards local over global processing. This paper examines whether there is a deficit in gestalt grouping in autism. Method: Twenty-five low-functioning children with autism and 25 controls who were matched for chronological age and verbal mental age took part in the study. Results:…

  12. Double dissociation of neural responses supporting perceptual and cognitive components of social cognition: Evidence from processing of others' pain

    PubMed Central

    Sessa, Paola; Meconi, Federica; Han, Shihui

    2014-01-01

    Models on how perceptual and cognitive information on others' mental states are treated by the cognitive architecture are often framed as duplex models considering two independent systems. In the context of the neuroscience of empathy analogous systems have been described. Using event-related potentials (i.e., ERPs) technique, we tested the hypothesis of temporal dissociation of two functional systems. We implemented a design in which perceptual (i.e., painful or neutral facial expressions) and contextual (i.e., painful or neutral related sentences) cues on others' mental states were orthogonally manipulated. Painful expressions selectively modulated the early activity at 110–360 ms over fronto-central and centro-parietal regions, whereas painful contexts selectively modulated the late activity at 400–840 ms over these same regions. Notably, the reactions to pain triggered by these cues added up when both were available, that is the joint reaction was characterized by additive effects. These findings favor a model assuming distinct neural paths of perceptual and cognitive processing, at least when the cognitive component is triggered by language. PMID:25502570

  13. Double dissociation of neural responses supporting perceptual and cognitive components of social cognition: evidence from processing of others' pain.

    PubMed

    Sessa, Paola; Meconi, Federica; Han, Shihui

    2014-01-01

    Models on how perceptual and cognitive information on others' mental states are treated by the cognitive architecture are often framed as duplex models considering two independent systems. In the context of the neuroscience of empathy analogous systems have been described. Using event-related potentials (i.e., ERPs) technique, we tested the hypothesis of temporal dissociation of two functional systems. We implemented a design in which perceptual (i.e., painful or neutral facial expressions) and contextual (i.e., painful or neutral related sentences) cues on others' mental states were orthogonally manipulated. Painful expressions selectively modulated the early activity at 110-360 ms over fronto-central and centro-parietal regions, whereas painful contexts selectively modulated the late activity at 400-840 ms over these same regions. Notably, the reactions to pain triggered by these cues added up when both were available, that is the joint reaction was characterized by additive effects. These findings favor a model assuming distinct neural paths of perceptual and cognitive processing, at least when the cognitive component is triggered by language. PMID:25502570

  14. Repetition blindness has a perceptual locus: evidence from online processing of targets in RSVP streams

    NASA Technical Reports Server (NTRS)

    Johnston, James C.; Hochhaus, Larry; Ruthruff, Eric

    2002-01-01

    Four experiments tested whether repetition blindness (RB; reduced accuracy reporting repetitions of briefly displayed items) is a perceptual or a memory-recall phenomenon. RB was measured in rapid serial visual presentation (RSVP) streams, with the task altered to reduce memory demands. In Experiment 1 only the number of targets (1 vs. 2) was reported, eliminating the need to remember target identities. Experiment 2 segregated repeated and nonrepeated targets into separate blocks to reduce bias against repeated targets. Experiments 3 and 4 required immediate "online" buttonpress responses to targets as they occurred. All 4 experiments showed very strong RB. Furthermore, the online response data showed clearly that the 2nd of the repeated targets is the one missed. The present results show that in the RSVP paradigm, RB occurs online during initial stimulus encoding and decision making. The authors argue that RB is indeed a perceptual phenomenon.

  15. Early Experience & Multisensory Perceptual Narrowing

    PubMed Central

    Lewkowicz, David J.

    2014-01-01

    Perceptual narrowing is a reflection of early experience and contributes in key ways to perceptual and cognitive development. In general, findings have shown that unisensory perceptual sensitivity in early infancy is broadly tuned such that young infants respond to, and discriminate, native as well as non-native sensory inputs, whereas older infants only respond to native inputs. Recently, my colleagues and I discovered that perceptual narrowing occurs at the multisensory processing level as well. The present article reviews this new evidence and puts it in the larger context of multisensory perceptual development and the role that perceptual experience plays in it. Together, the evidence on unisensory and multisensory narrowing shows that early experience shapes the emergence of perceptual specialization and expertise. PMID:24435505

  16. Chromatic Perceptual Learning but No Category Effects without Linguistic Input.

    PubMed

    Grandison, Alexandra; Sowden, Paul T; Drivonikou, Vicky G; Notman, Leslie A; Alexander, Iona; Davies, Ian R L

    2016-01-01

    Perceptual learning involves an improvement in perceptual judgment with practice, which is often specific to stimulus or task factors. Perceptual learning has been shown on a range of visual tasks but very little research has explored chromatic perceptual learning. Here, we use two low level perceptual threshold tasks and a supra-threshold target detection task to assess chromatic perceptual learning and category effects. Experiment 1 investigates whether chromatic thresholds reduce as a result of training and at what level of analysis learning effects occur. Experiment 2 explores the effect of category training on chromatic thresholds, whether training of this nature is category specific and whether it can induce categorical responding. Experiment 3 investigates the effect of category training on a higher level, lateralized target detection task, previously found to be sensitive to category effects. The findings indicate that performance on a perceptual threshold task improves following training but improvements do not transfer across retinal location or hue. Therefore, chromatic perceptual learning is category specific and can occur at relatively early stages of visual analysis. Additionally, category training does not induce category effects on a low level perceptual threshold task, as indicated by comparable discrimination thresholds at the newly learned hue boundary and adjacent test points. However, category training does induce emerging category effects on a supra-threshold target detection task. Whilst chromatic perceptual learning is possible, learnt category effects appear to be a product of left hemisphere processing, and may require the input of higher level linguistic coding processes in order to manifest. PMID:27252669

  17. Chromatic Perceptual Learning but No Category Effects without Linguistic Input

    PubMed Central

    Grandison, Alexandra; Sowden, Paul T.; Drivonikou, Vicky G.; Notman, Leslie A.; Alexander, Iona; Davies, Ian R. L.

    2016-01-01

    Perceptual learning involves an improvement in perceptual judgment with practice, which is often specific to stimulus or task factors. Perceptual learning has been shown on a range of visual tasks but very little research has explored chromatic perceptual learning. Here, we use two low level perceptual threshold tasks and a supra-threshold target detection task to assess chromatic perceptual learning and category effects. Experiment 1 investigates whether chromatic thresholds reduce as a result of training and at what level of analysis learning effects occur. Experiment 2 explores the effect of category training on chromatic thresholds, whether training of this nature is category specific and whether it can induce categorical responding. Experiment 3 investigates the effect of category training on a higher level, lateralized target detection task, previously found to be sensitive to category effects. The findings indicate that performance on a perceptual threshold task improves following training but improvements do not transfer across retinal location or hue. Therefore, chromatic perceptual learning is category specific and can occur at relatively early stages of visual analysis. Additionally, category training does not induce category effects on a low level perceptual threshold task, as indicated by comparable discrimination thresholds at the newly learned hue boundary and adjacent test points. However, category training does induce emerging category effects on a supra-threshold target detection task. Whilst chromatic perceptual learning is possible, learnt category effects appear to be a product of left hemisphere processing, and may require the input of higher level linguistic coding processes in order to manifest. PMID:27252669

  18. The process of processing: exploring the validity of Neisser's perceptual cycle model with accounts from critical decision-making in the cockpit.

    PubMed

    Plant, Katherine L; Stanton, Neville A

    2015-01-01

    The perceptual cycle model (PCM) has been widely applied in ergonomics research in domains including road, rail and aviation. The PCM assumes that information processing occurs in a cyclical manner drawing on top-down and bottom-up influences to produce perceptual exploration and actions. However, the validity of the model has not been addressed. This paper explores the construct validity of the PCM in the context of aeronautical decision-making. The critical decision method was used to interview 20 helicopter pilots about critical decision-making. The data were qualitatively analysed using an established coding scheme, and composite PCMs for incident phases were constructed. It was found that the PCM provided a mutually exclusive and exhaustive classification of the information-processing cycles for dealing with critical incidents. However, a counter-cycle was also discovered which has been attributed to skill-based behaviour, characteristic of experts. The practical applications and future research questions are discussed. Practitioner Summary: This paper explores whether information processing, when dealing with critical incidents, occurs in the manner anticipated by the perceptual cycle model. In addition to the traditional processing cycle, a reciprocal counter-cycle was found. This research can be utilised by those who use the model as an accident analysis framework.

  19. Action-Specific Influences on Perception and Post-Perceptual Processes: Present Controversies and Future Directions

    PubMed Central

    Philbeck, John W.; Witt, Jessica K.

    2015-01-01

    The action-specific perception account holds that people perceive the environment in terms of their ability to act in it. In this view, for example, decreased ability to climb a hill due to fatigue makes the hill visually appear to be steeper. Though influential, this account has not been universally accepted, and in fact a heated controversy has emerged. The opposing view holds that action capability has little or no influence on perception. Heretofore, the debate has been quite polarized, with efforts largely being focused on supporting one view and dismantling the other. We argue here that polarized debate can impede scientific progress and that the search for similarities between two sides of a debate can sharpen the theoretical focus of both sides and illuminate important avenues for future research. In this paper, we present a synthetic review of this debate, drawing from the literatures of both approaches, to clarify both the surprising similarities and the core differences between them. We critically evaluate existing evidence, discuss possible mechanisms of action-specific effects, and make recommendations for future research. A primary focus of future work will involve not only the development of methods that guard against action-specific post-perceptual effects, but also development of concrete, well-constrained underlying mechanisms. The criteria for what constitutes acceptable control of post-perceptual effects and what constitutes an appropriately specific mechanism vary between approaches, and bridging this gap is a central challenge for future research. PMID:26501227

  20. The shifting appearance/disappearance of holographic images and the dynamic ontology of perceptual and cognitive processes

    NASA Astrophysics Data System (ADS)

    Boissonnet, Philippe

    2013-02-01

    The French philosopher M Merleau-Ponty captured the dynamic of perception with his idea of the intertwining of perceiver and perceived. Light is what links them. In the case of holographic images, not only is spatial and colour perception the pure product of light, but this light information is always in the process of self-construction with our eyes, according to our movements and the point of view adopted. According to the aesthetic reception of a work of art, Holographic images vary greatly from those of cinema, photography and even every kind of digital 3D animation. This particular image's status truly makes perceptually apparent the "co-emergence" of light and our gaze. But holography never misleads us with respect to the precarious nature of our perceptions. We have no illusion as to the limits of our empirical understanding of the perceived reality. Holography, like our knowledge of the visible, thus brings to light the phenomenon of reality's "co-constitution" and contributes to a dynamic ontology of perceptual and cognitive processes. The cognitivist Francico Varela defines this as the paradigm of enaction,i which I will adapt and apply to the appearance/disappearance context of holographic images to bring out their affinities on a metaphorical level.

  1. Perceptual decision making for baseball pitch recognition: using P300 latency and amplitude to index attentional processing.

    PubMed

    Radlo, S J; Janelle, C M; Barba, D A; Frehlich, S G

    2001-03-01

    This study was designed to examine the perceptual and attentional processes associated with the effects of administering a cost-benefit precuing paradigm to intermediate and advance-level baseball batters. Psychophysiological and performance data obtained from 10 advanced and 10 intermediate-level players were compared. A total of 400 pitches (200 fastballs, 200 curveballs) was randomly presented via a large projection screen, and participants pressed one of two buttons to indicate the type of pitch thrown. Verbal precues were given for 300 of the pitches. Of those, 75% were valid, and 25% were invalid. Electroencephalographic data collected from the P location was used to assess the latency and amplitude of P300. Analysis of variance (Skill Level x Precue x Pitch) for P300 and reaction time (RT) indicated that intermediate batters produced shorter P300 latencies, larger P300 amplitudes, longer RTs, and less correct responses than the advanced batters; the effects were more pronounced for the curveballs. These results suggest that intermediate batters are less efficient in their perceptual decision-making processes due to greater limitations in attentional capacity when compared with advanced batters.

  2. Associating Neural Alterations and Genotype in Autism and Fragile X Syndrome: Incorporating Perceptual Phenotypes in Causal Modeling

    ERIC Educational Resources Information Center

    Bertone, Armando; Hanck, Julie; Kogan, Cary; Chaudhuri, Avi; Cornish, Kim

    2010-01-01

    We have previously described (see companion paper, this issue) the utility of using perceptual signatures for defining and dissociating condition-specific neural functioning underlying early visual processes in autism and FXS. These perceptually-driven hypotheses are based on differential performance evidenced only at the earliest stages of visual…

  3. Causal evidence for frontal cortex organization for perceptual decision making

    PubMed Central

    Nee, Derek Evan; Riddle, Justin; Larson, Alina Sue; D’Esposito, Mark

    2016-01-01

    Although recent research has shown that the frontal cortex has a critical role in perceptual decision making, an overarching theory of frontal functional organization for perception has yet to emerge. Perceptual decision making is temporally organized such that it requires the processes of selection, criterion setting, and evaluation. We hypothesized that exploring this temporal structure would reveal a large-scale frontal organization for perception. A causal intervention with transcranial magnetic stimulation revealed clear specialization along the rostrocaudal axis such that the control of successive stages of perceptual decision making was selectively affected by perturbation of successively rostral areas. Simulations with a dynamic model of decision making suggested distinct computational contributions of each region. Finally, the emergent frontal gradient was further corroborated by functional MRI. These causal results provide an organizational principle for the role of frontal cortex in the control of perceptual decision making and suggest specific mechanistic contributions for its different subregions. PMID:27162349

  4. Size does matter! Perceptual stimulus properties affect event-related potentials during feedback processing.

    PubMed

    Pfabigan, Daniela M; Sailer, Uta; Lamm, Claus

    2015-09-01

    The current study investigated whether or not the physical aspect of stimulus size has an effect on neuronal correlates of feedback processing. A time estimation task was administered applying three different feedback stimulus categories: small, middle, and large size stimuli. Apart from early visual ERPs such as P1 and N1 components, later feedback processing stages were also affected by the size of feedback stimuli. In particular, small size stimuli compared to middle and large size ones led to diminished amplitudes in both FRN and P300 components, despite intact discrimination between negative and positive outcomes in these two ERPs. In contrast, time estimation performance was not influenced by feedback size. The current results indicate that small size feedback stimuli were perceived as less salient and hence were processed less deeply than the others. This suggests that future feedback studies could manipulate feedback salience simply by presenting differently sized feedback stimuli, at least when the focus lies on FRN and P300 amplitude variation.

  5. Population response to natural images in the primary visual cortex encodes local stimulus attributes and perceptual processing.

    PubMed

    Ayzenshtat, Inbal; Gilad, Ariel; Zurawel, Guy; Slovin, Hamutal

    2012-10-01

    The primary visual cortex (V1) is extensively studied with a large repertoire of stimuli, yet little is known about its encoding of natural images. Using voltage-sensitive dye imaging in behaving monkeys, we measured neural population response evoked in V1 by natural images presented during a face/scramble discrimination task. The population response showed two distinct phases of activity: an early phase that was spread over most of the imaged area, and a late phase that was spatially confined. To study the detailed relation between the stimulus and the population response, we used a simple encoding model to compute a continuous map of the expected neural response based on local attributes of the stimulus (luminance and contrast), followed by an analytical retinotopic transformation. Then, we computed the spatial correlation between the maps of the expected and observed response. We found that the early response was highly correlated with the local luminance of the stimulus and was sufficient to effectively discriminate between stimuli at the single trial level. The late response, on the other hand, showed a much lower correlation to the local luminance, was confined to central parts of the face images, and was highly correlated with the animal's perceptual report. Our study reveals a continuous spatial encoding of low- and high-level features of natural images in V1. The low level is directly linked to the stimulus basic local attributes and the high level is correlated with the perceptual outcome of the stimulus processing.

  6. Perceptual Load Alters Visual Excitability

    ERIC Educational Resources Information Center

    Carmel, David; Thorne, Jeremy D.; Rees, Geraint; Lavie, Nilli

    2011-01-01

    Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load…

  7. Perceptual basis for reactive teleoperation.

    SciTech Connect

    Park, Y. S.; Ewing, T. F.; Boyle, J. M.; Yule, T. J.

    2001-08-28

    To enhance task performance in partially structured environment, enhancement of teleoperation was proposed by introducing autonomous behaviors. Such autonomy is implemented based on reactive robotic architecture, where reactive motor agents that directly couples sensory inputs and motor actions become the building blocks. To this end, presented in this paper is a perceptual basis for the motor agents. The perceptual basis consists of perceptual agents that extracts environmental information from a structured light vision system and provide action oriented perception for the corresponding motor agents. Rather than performing general scene reconstruction, a perceptual agent directly provides the motion reference for the motor behavior. Various sensory mechanisms--sensor fission, fusion, and fashion--becomes basic building blocks of the perception process. Since perception is a process deeply intertwined with the motor actions, active perception may also incorporate motor behaviors as an integral perceptual process.

  8. Simple perceptual color space for color specification and real-time processing

    NASA Astrophysics Data System (ADS)

    Kotsarenko, Yuriy; Ramos, Fernando

    2011-08-01

    In this work an alternative color space is described that defines the color elements in terms of approximated brightness, hue and saturation, similar to other color spaces commonly used in computer applications. The classical color spaces such as HSL and HSV in the form that is widely used are made for convenience, and do not model colors based on human perception. Other classical color spaces such as CIELAB, DIN99 and even more recent CIECAM-based color spaces are too cumbersome and difficult to work with. The proposed alternative, on the other hand, is simple to work with and has its "lightness" component tuned up to represent the perceived brightness closer to the reality. It is based on how luma is calculated in color spaces such as YUV and YIQ among others, but instead of using constant coefficients, it uses Euclidean distance formula with weighting coefficients. Several experiments are described that illustrate the proposed color space visualized in 3D and compared to other color spaces in perceptual terms and performance benchmarks. This is aided by a novel technique that allows normalizing the chroma of existing color spaces within a fixed interval. The experiments show that the proposed color space is a viable alternative for applications that already use HSV and HSL. A practical application is described, where the color space is used for 3D illumination with specular reflections running on dedicated graphics processor unit using shaders. This resolves visual defects present in the classical approaches that use RGB color space.

  9. Process for coal liquefaction in staged dissolvers

    DOEpatents

    Roberts, George W.; Givens, Edwin N.; Skinner, Ronald W.

    1983-01-01

    There is described an improved liquefaction process by which coal is converted to a low ash and low sulfur carbonaceous material that can be used as a fuel in an environmentally acceptable manner without costly gas scrubbing equipment. In the process, coal is slurried with a pasting oil, passed through a preheater and at least two dissolvers in series in the presence of hydrogen-rich gases at elevated temperatures and pressures. Solids, including mineral ash and unconverted coal macerals, are separated from the condensed reactor effluent. In accordance with the improved process, the first dissolver is operated at a higher temperature than the second dissolver. This temperature sequence produces improved product selectivity and permits the incorporation of sufficient hydrogen in the solvent for adequate recycle operations.

  10. The perceptual reality of synesthetic colors

    PubMed Central

    Palmeri, Thomas J.; Blake, Randolph; Marois, René; Flanery, Marci A.; Whetsell, William

    2002-01-01

    Synesthesia is a remarkable, rare condition where an individual has multimodal perceptual experiences from a unimodal sensory event. We have studied such an individual, an adult male for whom achromatic words and alphanumeric characters are seen in vivid, reliable colors. We used a variety of perceptual tasks to document the perceptual reality of synesthetic colors and to begin to localize the stage of visual processing where this anomalous binding of externally specified form and internally generated color may take place. Synesthetic colors were elicited by forms defined solely by binocular cues or solely by motion cues, which implies a central locus of visual processing for synesthetic binding of form and color. Also included among our measurements was a difficult visual search task on which non-synesthetic subjects required an effortful search through the visual display. Our subject, in contrast to non-synesthetic subjects, accomplished the task with relative ease because the target of the search had a different synesthetic color from the distractors. Thus, synesthetic experiences appear to originate from a binding of color and form that takes place within central stages of visual processing. PMID:11904456

  11. Helping Perceptually Handicapped Children

    ERIC Educational Resources Information Center

    Rose, Helen S.

    1974-01-01

    Five children diagnosed as having a perceptual problem as revealed by the Bender Visual Motor Gestalt Test received special tutoring to help develop their visual discrimination abilities. The six-week program for teaching the concept of shapes employed kinesthetic, visual, tactile, and verbal processes. (CS)

  12. Pyrosol process offers attractive two-stage liquefaction options

    SciTech Connect

    Not Available

    1986-09-01

    The Pyrosol process is a new two-stage process to convert coal into oil which comparatively consumes much less hydrogen and operates at considerably lower pressures. The PYROSOL process only partly liquefies the coal in the first stage using mild hydrogenation conditions. Approximately 25% of the daf coal is converted into distillates. The remaining residue, which contains a high amount of bitumen, is then coked in the second stage. In the hydrocoker the residue is cracked into additional oil and coke under a hydrogen atmosphere. The PYROSOL process can be configured for direct coal liquefaction or for coprocessing coal and oil. Only the liquefaction scheme is described in this paper.

  13. The Role of Bottom-Up Processing in Perceptual Categorization by 3- to 4-Month-Old Infants: Simulations and Data

    ERIC Educational Resources Information Center

    French, Robert M.; Mareschal, Denis; Mermillod, Martial; Quinn, Paul C.

    2004-01-01

    Disentangling bottom-up and top-down processing in adult category learning is notoriously difficult. Studying category learning in infancy provides a simple way of exploring category learning while minimizing the contribution of top-down information. Three- to 4-month-old infants presented with cat or dog images will form a perceptual category…

  14. Virtually-induced threat in Parkinson's: Dopaminergic interactions between anxiety and sensory-perceptual processing while walking.

    PubMed

    Ehgoetz Martens, Kaylena A; Ellard, Colin G; Almeida, Quincy J

    2015-12-01

    Research evidence has suggested that anxiety influences gait in PD, with an identified dopa-sensitive gait response in highly anxious PD. It has been well-established that accurate perception of the environment and sensory feedback is essential for gait. Arguably since sensory and perceptual deficits have been noted in PD, anxiety has the potential to exacerbate movement impairments, since one might expect that reducing resources needed to overcome or compensate for sensory-perceptual deficits may lead to even more severe gait impairments. It is possible that anxiety in threatening situations might consume more processing resources, limiting the ability to process information about the environment or one's own movement (sensory feedback) especially in highly anxious PD. Therefore, the current study aimed to (i) evaluate whether processing of threat-related aspects of the environment was influenced by anxiety, (ii) evaluate whether anxiety influences the ability to utilize sensory feedback in PD while walking in threatening situations, and (iii) further understand the role of dopaminergic medication on these processes in threatening situations in PD. Forty-eight participants (24 HC; 12 Low Anxious [LA-PD], 12 Highly Anxious [HA-PD]) completed 20 walking trials in virtual reality across a plank that was (i) located on the ground (GROUND) (ii) located above a deep pit (ELEVATED); while provided with or without visual feedback about their lower limbs (+VF; -VF). After walking across the plank, participants were asked to judge the width of the plank they had just walked across. The plank varied in size from 60-100 cm. Both ON and OFF dopaminergic medication states were evaluated in PD. Gait parameters, judgment error and self-reported anxiety levels were measured. Results showed that HA-PD reported greater levels of anxiety overall (p<0.001) compared to HC and LA-PD, and all participants reported greater anxiety during the ELEVATED condition compared to GROUND (p=0

  15. Virtually-induced threat in Parkinson's: Dopaminergic interactions between anxiety and sensory-perceptual processing while walking.

    PubMed

    Ehgoetz Martens, Kaylena A; Ellard, Colin G; Almeida, Quincy J

    2015-12-01

    Research evidence has suggested that anxiety influences gait in PD, with an identified dopa-sensitive gait response in highly anxious PD. It has been well-established that accurate perception of the environment and sensory feedback is essential for gait. Arguably since sensory and perceptual deficits have been noted in PD, anxiety has the potential to exacerbate movement impairments, since one might expect that reducing resources needed to overcome or compensate for sensory-perceptual deficits may lead to even more severe gait impairments. It is possible that anxiety in threatening situations might consume more processing resources, limiting the ability to process information about the environment or one's own movement (sensory feedback) especially in highly anxious PD. Therefore, the current study aimed to (i) evaluate whether processing of threat-related aspects of the environment was influenced by anxiety, (ii) evaluate whether anxiety influences the ability to utilize sensory feedback in PD while walking in threatening situations, and (iii) further understand the role of dopaminergic medication on these processes in threatening situations in PD. Forty-eight participants (24 HC; 12 Low Anxious [LA-PD], 12 Highly Anxious [HA-PD]) completed 20 walking trials in virtual reality across a plank that was (i) located on the ground (GROUND) (ii) located above a deep pit (ELEVATED); while provided with or without visual feedback about their lower limbs (+VF; -VF). After walking across the plank, participants were asked to judge the width of the plank they had just walked across. The plank varied in size from 60-100 cm. Both ON and OFF dopaminergic medication states were evaluated in PD. Gait parameters, judgment error and self-reported anxiety levels were measured. Results showed that HA-PD reported greater levels of anxiety overall (p<0.001) compared to HC and LA-PD, and all participants reported greater anxiety during the ELEVATED condition compared to GROUND (p=0

  16. Impaired perceptual processing and conceptual cognition in patients with anxiety disorders: a pilot study with the binocular depth inversion paradigm.

    PubMed

    Passie, Torsten; Schneider, Udo; Borsutzky, Mathias; Breyer, Roger; Emrich, Hinderk M; Bandelow, Borwin; Schmid-Ott, Gerhard

    2013-01-01

    The binocular depth inversion test (BDIT) measures a common illusion of visual perception whereby implausible objects are seen as normal, e.g., a hollow face is perceived as a normal, convex face. Such inversion is frequent, especially for objects with a high degree of familiarity. Under normal conditions, cognitive factors apparently override the binocular disparity cues of stereopsis. This internal mechanism of "censorship" of perception, which balances "top-down" and "bottom-up" processes of perception to come to a cognitive coherence, which is congruent to previous experience and concepts, appears to be disturbed in (pro-)psychotic states. The BDIT has been shown to be a sensitive measure of impaired higher visual processing and conceptual cognition common to conditions including schizophrenia, cannabinoid-intoxication, and sleep deprivation but not depression. In this pilot study, we tested the performance of patients with anxiety disorders (ICD-10 F40 and F41) compared to matched controls using the BDIT paradigm. Anxiety patients scored significantly higher on the BDIT than controls, in a range comparable to propsychotic conditions. The findings suggest that anxiety patients could have abnormalities in central perceptual processing, top-down processing (conceptual cognition), and reality testing similar to (pro-)psychotic conditions. Implications of these findings are discussed in relation to therapeutic interventions with anxiety disorders. PMID:23186162

  17. Perceptual conflict during sensorimotor integration processes - a neurophysiological study in response inhibition

    PubMed Central

    Chmielewski, Witold X.; Beste, Christian

    2016-01-01

    A multitude of sensory inputs needs to be processed during sensorimotor integration. A crucial factor for detecting relevant information is its complexity, since information content can be conflicting at a perceptual level. This may be central to executive control processes, such as response inhibition. This EEG study aims to investigate the system neurophysiological mechanisms behind effects of perceptual conflict on response inhibition. We systematically modulated perceptual conflict by integrating a Global-local task with a Go/Nogo paradigm. The results show that conflicting perceptual information, in comparison to non-conflicting perceptual information, impairs response inhibition performance. This effect was evident regardless of whether the relevant information for response inhibition is displayed on the global, or local perceptual level. The neurophysiological data suggests that early perceptual/ attentional processing stages do not underlie these modulations. Rather, processes at the response selection level (P3), play a role in changed response inhibition performance. This conflict-related impairment of inhibitory processes is associated with activation differences in (inferior) parietal areas (BA7 and BA40) and not as commonly found in the medial prefrontal areas. This suggests that various functional neuroanatomical structures may mediate response inhibition and that the functional neuroanatomical structures involved depend on the complexity of sensory integration processes. PMID:27222225

  18. Adaptation and perceptual norms

    NASA Astrophysics Data System (ADS)

    Webster, Michael A.; Yasuda, Maiko; Haber, Sara; Leonard, Deanne; Ballardini, Nicole

    2007-02-01

    We used adaptation to examine the relationship between perceptual norms--the stimuli observers describe as psychologically neutral, and response norms--the stimulus levels that leave visual sensitivity in a neutral or balanced state. Adapting to stimuli on opposite sides of a neutral point (e.g. redder or greener than white) biases appearance in opposite ways. Thus the adapting stimulus can be titrated to find the unique adapting level that does not bias appearance. We compared these response norms to subjectively defined neutral points both within the same observer (at different retinal eccentricities) and between observers. These comparisons were made for visual judgments of color, image focus, and human faces, stimuli that are very different and may depend on very different levels of processing, yet which share the property that for each there is a well defined and perceptually salient norm. In each case the adaptation aftereffects were consistent with an underlying sensitivity basis for the perceptual norm. Specifically, response norms were similar to and thus covaried with the perceptual norm, and under common adaptation differences between subjectively defined norms were reduced. These results are consistent with models of norm-based codes and suggest that these codes underlie an important link between visual coding and visual experience.

  19. Perceptual Training Strongly Improves Visual Motion Perception in Schizophrenia

    ERIC Educational Resources Information Center

    Norton, Daniel J.; McBain, Ryan K.; Ongur, Dost; Chen, Yue

    2011-01-01

    Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients' perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it…

  20. The Competitive Influences of Perceptual Load and Working Memory Guidance on Selective Attention.

    PubMed

    Tan, Jinfeng; Zhao, Yuanfang; Wang, Lijun; Tian, Xia; Cui, Yan; Yang, Qian; Pan, Weigang; Zhao, Xiaoyue; Chen, Antao

    2015-01-01

    The perceptual load theory in selective attention literature proposes that the interference from task-irrelevant distractor is eliminated when perceptual capacity is fully consumed by task-relevant information. However, the biased competition model suggests that the contents of working memory (WM) can guide attentional selection automatically, even when this guidance is detrimental to visual search. An intriguing but unsolved question is what will happen when selective attention is influenced by both perceptual load and WM guidance. To study this issue, behavioral performances and event-related potentials (ERPs) were recorded when participants were presented with a cue to either identify or hold in memory and had to perform a visual search task subsequently, under conditions of low or high perceptual load. Behavioural data showed that high perceptual load eliminated the attentional capture by WM. The ERP results revealed an obvious WM guidance effect in P1 component with invalid trials eliciting larger P1 than neutral trials, regardless of the level of perceptual load. The interaction between perceptual load and WM guidance was significant for the posterior N1 component. The memory guidance effect on N1 was eliminated by high perceptual load. Standardized Low Resolution Electrical Tomography Analysis (sLORETA) showed that the WM guidance effect and the perceptual load effect on attention can be localized into the occipital area and parietal lobe, respectively. Merely identifying the cue produced no effect on the P1 or N1 component. These results suggest that in selective attention, the information held in WM could capture attention at the early stage of visual processing in the occipital cortex. Interestingly, this initial capture of attention by WM could be modulated by the level of perceptual load and the parietal lobe mediates target selection at the discrimination stage.

  1. Contextual and Perceptual Brain Processes Underlying Moral Cognition: A Quantitative Meta-Analysis of Moral Reasoning and Moral Emotions

    PubMed Central

    Sevinc, Gunes; Spreng, R. Nathan

    2014-01-01

    moral input is affected by task demands. The results provide novel insight into distinct features of moral cognition, including the generation of moral context through associative processes and the perceptual detection of moral salience. PMID:24503959

  2. Stage efficiency in the analysis of thermochemical water decomposition processes

    NASA Technical Reports Server (NTRS)

    Conger, W. L.; Funk, J. E.; Carty, R. H.; Soliman, M. A.; Cox, K. E.

    1976-01-01

    The procedure for analyzing thermochemical water-splitting processes using the figure of merit is expanded to include individual stage efficiencies and loss coefficients. The use of these quantities to establish the thermodynamic insufficiencies of each stage is shown. A number of processes are used to illustrate these concepts and procedures and to demonstrate the facility with which process steps contributing most to the cycle efficiency are found. The procedure allows attention to be directed to those steps of the process where the greatest increase in total cycle efficiency can be obtained.

  3. Verbal Labels Modulate Perceptual Object Processing in 1-Year-Old Children

    ERIC Educational Resources Information Center

    Gliga, Teodora; Volein, Agnes; Csibra, Gergely

    2010-01-01

    Whether verbal labels help infants visually process and categorize objects is a contentious issue. Using electroencephalography, we investigated whether possessing familiar or novel labels for objects directly enhances 1-year-old children's neural processes underlying the perception of those objects. We found enhanced gamma-band (20-60 Hz)…

  4. Perceptual expertise: can sensorimotor experience change holistic processing and left-side bias?

    PubMed

    Tso, Ricky Van-yip; Au, Terry Kit-fong; Hsiao, Janet Hui-wen

    2014-09-01

    Holistic processing and left-side bias are both behavioral markers of expert face recognition. By contrast, expert recognition of characters in Chinese orthography involves left-side bias but reduced holistic processing, although faces and Chinese characters share many visual properties. Here, we examined whether this reduction in holistic processing of Chinese characters can be better explained by writing experience than by reading experience. Compared with Chinese nonreaders, Chinese readers who had limited writing experience showed increased holistic processing, whereas Chinese readers who could write characters fluently showed reduced holistic processing. This result suggests that writing and sensorimotor experience can modulate holistic-processing effects and that the reduced holistic processing observed in expert Chinese readers may depend mostly on writing experience. However, both expert writers and writers with limited experience showed similarly stronger left-side bias than novices did in processing mirror-symmetric Chinese characters; left-side bias may therefore be a robust expertise marker for object recognition that is uninfluenced by sensorimotor experience.

  5. Perceptual Decoding Processes for Language in a Visual Mode and for Language in an Auditory Mode.

    ERIC Educational Resources Information Center

    Myerson, Rosemarie Farkas

    The purpose of this paper is to gain insight into the nature of the reading process through an understanding of the general nature of sensory processing mechanisms which reorganize and restructure input signals for central recognition, and an understanding of how the grammar of the language functions in defining the set of possible sentences in…

  6. Habitat Fragmentation Drives Plant Community Assembly Processes across Life Stages

    PubMed Central

    Hu, Guang; Feeley, Kenneth J.; Yu, Mingjian

    2016-01-01

    Habitat fragmentation is one of the principal causes of biodiversity loss and hence understanding its impacts on community assembly and disassembly is an important topic in ecology. We studied the relationships between fragmentation and community assembly processes in the land-bridge island system of Thousand Island Lake in East China. We focused on the changes in species diversity and phylogenetic diversity that occurred between life stages of woody plants growing on these islands. The observed diversities were compared with the expected diversities from random null models to characterize assembly processes. Regression tree analysis was used to illustrate the relationships between island attributes and community assembly processes. We found that different assembly processes predominate in the seedlings-to-saplings life-stage transition (SS) vs. the saplings-to-trees transition (ST). Island area was the main attribute driving the assembly process in SS. In ST, island isolation was more important. Within a fragmented landscape, the factors driving community assembly processes were found to differ between life stage transitions. Environmental filtering had a strong effect on the seedlings-to-saplings life-stage transition. Habitat isolation and dispersal limitation influenced all plant life stages, but had a weaker effect on communities than area. These findings add to our understanding of the processes driving community assembly and species coexistence in the context of pervasive and widespread habitat loss and fragmentation. PMID:27427960

  7. Habitat Fragmentation Drives Plant Community Assembly Processes across Life Stages.

    PubMed

    Hu, Guang; Feeley, Kenneth J; Yu, Mingjian

    2016-01-01

    Habitat fragmentation is one of the principal causes of biodiversity loss and hence understanding its impacts on community assembly and disassembly is an important topic in ecology. We studied the relationships between fragmentation and community assembly processes in the land-bridge island system of Thousand Island Lake in East China. We focused on the changes in species diversity and phylogenetic diversity that occurred between life stages of woody plants growing on these islands. The observed diversities were compared with the expected diversities from random null models to characterize assembly processes. Regression tree analysis was used to illustrate the relationships between island attributes and community assembly processes. We found that different assembly processes predominate in the seedlings-to-saplings life-stage transition (SS) vs. the saplings-to-trees transition (ST). Island area was the main attribute driving the assembly process in SS. In ST, island isolation was more important. Within a fragmented landscape, the factors driving community assembly processes were found to differ between life stage transitions. Environmental filtering had a strong effect on the seedlings-to-saplings life-stage transition. Habitat isolation and dispersal limitation influenced all plant life stages, but had a weaker effect on communities than area. These findings add to our understanding of the processes driving community assembly and species coexistence in the context of pervasive and widespread habitat loss and fragmentation. PMID:27427960

  8. Task-Set Reconfiguration Suspends Perceptual Processing: Evidence from Semantic Priming during the Attentional Blink

    ERIC Educational Resources Information Center

    Vachon, Francois; Tremblay, Sebastien; Jones, Dylan M.

    2007-01-01

    When two visual targets, Target 1 (T1) and Target 2 (T2), are presented among a rapid sequence of distractors, processing of T1 produces an attentional blink. Typically, processing of T2 is markedly impaired, except when T1 and T2 are adjacent (Lag 1 sparing). However, if a shift of task set--a change in task requirements from T1 to T2--occurs,…

  9. Prolonged perceptual learning of positional acuity in adult amblyopia: perceptual template retuning dynamics.

    PubMed

    Li, Roger W; Klein, Stanley A; Levi, Dennis M

    2008-12-24

    Amblyopia is a developmental abnormality that results in physiological alterations in the visual cortex and impairs form vision. It is often successfully treated by patching the sound eye in infants and young children, but is generally considered to be untreatable in adults. However, a number of recent studies suggest that repetitive practice of a visual task using the amblyopic eye results in improved performance in both children and adults with amblyopia. These perceptual learning studies have used relatively brief periods of practice; however, clinical studies have shown that the time-constant for successful patching is long. The time-constant for perceptual learning in amblyopia is still unknown. Here we show that the time-constant for perceptual learning depends on the degree of amblyopia. Severe amblyopia requires >50 h (approximately equal to 35,000 trials) to reach plateau, yielding as much as a five-fold improvement in performance at a rate of approximately equal to 1.5%/h. There is significant transfer of learning from the amblyopic to the dominant eye, suggesting that the learning reflects alterations in higher decision stages of processing. Using a reverse correlation technique, we document, for the first time, a dynamic retuning of the amblyopic perceptual decision template and a substantial reduction in internal spatial distortion. These results show that the mature amblyopic brain is surprisingly malleable, and point to more intensive treatment methods for amblyopia.

  10. A predictive processing theory of sensorimotor contingencies: Explaining the puzzle of perceptual presence and its absence in synesthesia

    PubMed Central

    Seth, Anil K.

    2014-01-01

    Normal perception involves experiencing objects within perceptual scenes as real, as existing in the world. This property of “perceptual presence” has motivated “sensorimotor theories” which understand perception to involve the mastery of sensorimotor contingencies. However, the mechanistic basis of sensorimotor contingencies and their mastery has remained unclear. Sensorimotor theory also struggles to explain instances of perception, such as synesthesia, that appear to lack perceptual presence and for which relevant sensorimotor contingencies are difficult to identify. On alternative “predictive processing” theories, perceptual content emerges from probabilistic inference on the external causes of sensory signals, however, this view has addressed neither the problem of perceptual presence nor synesthesia. Here, I describe a theory of predictive perception of sensorimotor contingencies which (1) accounts for perceptual presence in normal perception, as well as its absence in synesthesia, and (2) operationalizes the notion of sensorimotor contingencies and their mastery. The core idea is that generative models underlying perception incorporate explicitly counterfactual elements related to how sensory inputs would change on the basis of a broad repertoire of possible actions, even if those actions are not performed. These “counterfactually-rich” generative models encode sensorimotor contingencies related to repertoires of sensorimotor dependencies, with counterfactual richness determining the degree of perceptual presence associated with a stimulus. While the generative models underlying normal perception are typically counterfactually rich (reflecting a large repertoire of possible sensorimotor dependencies), those underlying synesthetic concurrents are hypothesized to be counterfactually poor. In addition to accounting for the phenomenology of synesthesia, the theory naturally accommodates phenomenological differences between a range of experiential

  11. The discovery of processing stages: Extension of Sternberg's method.

    PubMed

    Anderson, John R; Zhang, Qiong; Borst, Jelmer P; Walsh, Matthew M

    2016-10-01

    We introduce a method for measuring the number and durations of processing stages from the electroencephalographic signal and apply it to the study of associative recognition. Using an extension of past research that combines multivariate pattern analysis with hidden semi-Markov models, the approach identifies on a trial-by-trial basis where brief sinusoidal peaks (called bumps) are added to the ongoing electroencephalographic signal. We propose that these bumps mark the onset of critical cognitive stages in processing. The results of the analysis can be used to guide the development of detailed process models. Applied to the associative recognition task, the hidden semi-Markov models multivariate pattern analysis method indicates that the effects of associative strength and probe type are localized to a memory retrieval stage and a decision stage. This is in line with a previously developed the adaptive control of thought-rational process model, called ACT-R, of the task. As a test of the generalization of our method we also apply it to a data set on the Sternberg working memory task collected by Jacobs, Hwang, Curran, and Kahana (2006). The analysis generalizes robustly, and localizes the typical set size effect in a late comparison/decision stage. In addition to providing information about the number and durations of stages in associative recognition, our analysis sheds light on the event-related potential components implicated in the study of recognition memory. (PsycINFO Database Record

  12. Catalytic two-stage coal hydrogenation and hydroconversion process

    DOEpatents

    MacArthur, James B.; McLean, Joseph B.; Comolli, Alfred G.

    1989-01-01

    A process for two-stage catalytic hydrogenation and liquefaction of coal to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal is slurried with a process-derived liquid solvent and fed at temperature below about 650.degree. F. into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils at conditions favoring hydrogenation reactions. The first stage reactor is maintained at 650.degree.-800.degree. F. temperature, 1000-4000 psig hydrogen partial pressure, and 10-60 lb coal/hr/ft.sup.3 reactor space velocity. The partially hydrogenated material from the first stage reaction zone is passed directly to the close-coupled second stage catalytic reaction zone maintained at a temperature at least about 25.degree. F. higher than for the first stage reactor and within a range of 750.degree.-875.degree. F. temperature for further hydrogenation and thermal hydroconversion reactions. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, which results in significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of undesirable residuum and unconverted coal and hydrocarbon gases, with use of less energy to obtain the low molecular weight products, while catalyst life is substantially increased.

  13. A Perceptual Process Approach to Selecting Color Scales for Complex Visualizations

    ERIC Educational Resources Information Center

    Breslow, Leonard A.; Trafton, J. Gregory; Ratwani, Raj M.

    2009-01-01

    Previous research has shown that multicolored scales are superior to ordered brightness scales for supporting identification tasks on complex visualizations (categorization, absolute numeric value judgments, etc.), whereas ordered brightness scales are superior for relative comparison tasks (greater/less). We examined the processes by which such…

  14. Initial stages of the ion beam mixing process

    SciTech Connect

    Traverse, A.; Le Boite, M.G.; Nevot, L.; Pardo, B.; Corno, J.

    1987-12-07

    The grazing x-ray reflectometry technique, performed on irradiated periodic multilayers, was used to study the early stages of the ion beam mixing process. We present our first results, obtained on NiAu samples irradiated with He ions. The experimental fluence dependence of the effective diffusion coefficient is in good agreement with a calculation based on a purely ballistic process.

  15. Perceptual demand modulates activation of human auditory cortex in response to task-irrelevant sounds.

    PubMed

    Sabri, Merav; Humphries, Colin; Verber, Matthew; Mangalathu, Jain; Desai, Anjali; Binder, Jeffrey R; Liebenthal, Einat

    2013-09-01

    In the visual modality, perceptual demand on a goal-directed task has been shown to modulate the extent to which irrelevant information can be disregarded at a sensory-perceptual stage of processing. In the auditory modality, the effect of perceptual demand on neural representations of task-irrelevant sounds is unclear. We compared simultaneous ERPs and fMRI responses associated with task-irrelevant sounds across parametrically modulated perceptual task demands in a dichotic-listening paradigm. Participants performed a signal detection task in one ear (Attend ear) while ignoring task-irrelevant syllable sounds in the other ear (Ignore ear). Results revealed modulation of syllable processing by auditory perceptual demand in an ROI in middle left superior temporal gyrus and in negative ERP activity 130-230 msec post stimulus onset. Increasing the perceptual demand in the Attend ear was associated with a reduced neural response in both fMRI and ERP to task-irrelevant sounds. These findings are in support of a selection model whereby ongoing perceptual demands modulate task-irrelevant sound processing in auditory cortex.

  16. Computational models of music perception and cognition I: The perceptual and cognitive processing chain

    NASA Astrophysics Data System (ADS)

    Purwins, Hendrik; Herrera, Perfecto; Grachten, Maarten; Hazan, Amaury; Marxer, Ricard; Serra, Xavier

    2008-09-01

    We present a review on perception and cognition models designed for or applicable to music. An emphasis is put on computational implementations. We include findings from different disciplines: neuroscience, psychology, cognitive science, artificial intelligence, and musicology. The article summarizes the methodology that these disciplines use to approach the phenomena of music understanding, the localization of musical processes in the brain, and the flow of cognitive operations involved in turning physical signals into musical symbols, going from the transducers to the memory systems of the brain. We discuss formal models developed to emulate, explain and predict phenomena involved in early auditory processing, pitch processing, grouping, source separation, and music structure computation. We cover generic computational architectures of attention, memory, and expectation that can be instantiated and tuned to deal with specific musical phenomena. Criteria for the evaluation of such models are presented and discussed. Thereby, we lay out the general framework that provides the basis for the discussion of domain-specific music models in Part II.

  17. Retraining in literal alexia: substitution of a right hemisphere perceptual strategy for impaired left hemispheric processing.

    PubMed

    Carmon, A; Gordon, H W; Bental, E; Harness, B Z

    1977-07-01

    An adult patient with literal alexia, agraphia, slight anomia, and dyscalculia due to a left hemisphere infarct showed lack of sequential skills while pattern recognition remained intact. Some words were recognized as patterns, but could not be read phonetically. Therapy concentrated on forming an association of the visual pattern of the complete word with the retained auditory pattern. In this way the patient learned to read several hundred words and short phrases, even as anomia worsened. The patterns learned could not be generalized to noun declension or verb conjugation, or broken into smaller words. This learning process is characteristic of right hemispheric skills which were utilized as left hemispheric functions deteriorated. PMID:617048

  18. What neuroscience can tell about intuitive processes in the context of perceptual discovery.

    PubMed

    Volz, Kirsten G; von Cramon, D Yves

    2006-12-01

    According to the Oxford English Dictionary, intuition is "the ability to understand or know something immediately, without conscious reasoning." Most people would agree that intuitive responses appear as ideas or feelings that subsequently guide our thoughts and behaviors. It is proposed that people continuously, without conscious attention, recognize patterns in the stream of sensations that impinge upon them. What exactly is being recognized is not clear yet, but we assume that people detect potential content based on only a few aspects of the input (i.e., the gist). The result is a vague perception of coherence which is not explicitly describable but instead embodied in a "gut feeling" or an initial guess, which subsequently biases thought and inquiry. To approach the nature of intuitive processes, we used functional magnetic resonance imaging when participants were working at a modified version of the Waterloo Gestalt Closure Task. Starting from our conceptualization that intuition involves an informed judgment in the context of discovery, we expected activation within the median orbito-frontal cortex (OFC), as this area receives input from all sensory modalities and has been shown to be crucially involved in emotionally driven decisions. Results from a direct contrast between intuitive and nonintuitive judgments, as well as from a parametric analysis, revealed the median OFC, the lateral portion of the amygdala, anterior insula, and ventral occipito-temporal regions to be activated. Based on these findings, we suggest our definition of intuition to be promising and a good starting point for future research on intuitive processes.

  19. Transient perceptual neglect: visual working memory load affects conscious object processing.

    PubMed

    Emrich, Stephen M; Burianová, Hana; Ferber, Susanne

    2011-10-01

    Visual working memory (VWM) is a capacity-limited cognitive resource that plays an important role in complex cognitive behaviors. Recent studies indicate that regions subserving VWM may play a role in the perception and recognition of visual objects, suggesting that conscious object perception may depend on the same cognitive and neural architecture that supports the maintenance of visual object information. In the present study, we examined this question by testing object processing under a concurrent VWM load. Under a high VWM load, recognition was impaired for objects presented in the left visual field, in particular when two objects were presented simultaneously. Multivariate fMRI revealed that two independent but partially overlapping networks of brain regions contribute to object recognition. The first network consisted of regions involved in VWM encoding and maintenance. Importantly, these regions were also sensitive to object load. The second network comprised regions of the ventral temporal lobes traditionally associated with object recognition. Importantly, activation in both networks predicted object recognition performance. These results indicate that information processing in regions that mediate VWM may be critical to conscious visual perception. Moreover, the observation of a hemifield asymmetry in object recognition performance has important theoretical and clinical significance for the study of visual neglect.

  20. [Recent trends in the psychology of music perception: the perceptual processes of melody and musical pitch].

    PubMed

    Tsuzaki, M

    1988-08-01

    In this article some of the recent researches on music perception are reviewed, with a special emphasis upon those that concern melody organization and musical pitch. Lerdahl and Jackendoff (1983) pointed out that there is a grammatical parallel between music and language, and presented some grammatical rules for the tonal music. Serafine (1983) cautioned us not to confuse the "style principles" with the "musical cognitive process". The recent experiments on musical pitch and melody has reinforced the psychological validity of musical segmentation, tonality, pitch chroma, scale, and key. Theoretical approaches to the relations in the scale systems gave the possibility of a "new scale system" for use in psychological experiments, while the recent pitch models has made it possible for us to control tonality and to generate tones never used before in playing music. The need for a greater cross-stylistic generality of psychological concepts in music and the farther clarification of the "musical cognitive process" through experiments utilizing the "new scale system" and the "new tones" are indicated.

  1. Perceptual and category processing of the Uncanny Valley hypothesis' dimension of human likeness: some methodological issues.

    PubMed

    Cheetham, Marcus; Jancke, Lutz

    2013-01-01

    Mori's Uncanny Valley Hypothesis(1,2) proposes that the perception of humanlike characters such as robots and, by extension, avatars (computer-generated characters) can evoke negative or positive affect (valence) depending on the object's degree of visual and behavioral realism along a dimension of human likeness (DHL) (Figure 1). But studies of affective valence of subjective responses to variously realistic non-human characters have produced inconsistent findings (3, 4, 5, 6). One of a number of reasons for this is that human likeness is not perceived as the hypothesis assumes. While the DHL can be defined following Mori's description as a smooth linear change in the degree of physical humanlike similarity, subjective perception of objects along the DHL can be understood in terms of the psychological effects of categorical perception (CP) (7). Further behavioral and neuroimaging investigations of category processing and CP along the DHL and of the potential influence of the dimension's underlying category structure on affective experience are needed. This protocol therefore focuses on the DHL and allows examination of CP. Based on the protocol presented in the video as an example, issues surrounding the methodology in the protocol and the use in "uncanny" research of stimuli drawn from morph continua to represent the DHL are discussed in the article that accompanies the video. The use of neuroimaging and morph stimuli to represent the DHL in order to disentangle brain regions neurally responsive to physical human-like similarity from those responsive to category change and category processing is briefly illustrated. PMID:23770728

  2. Perceptual and Category Processing of the Uncanny Valley Hypothesis' Dimension of Human Likeness: Some Methodological Issues

    PubMed Central

    Cheetham, Marcus; Jancke, Lutz

    2013-01-01

    Mori's Uncanny Valley Hypothesis1,2 proposes that the perception of humanlike characters such as robots and, by extension, avatars (computer-generated characters) can evoke negative or positive affect (valence) depending on the object's degree of visual and behavioral realism along a dimension of human likeness (DHL) (Figure 1). But studies of affective valence of subjective responses to variously realistic non-human characters have produced inconsistent findings 3, 4, 5, 6. One of a number of reasons for this is that human likeness is not perceived as the hypothesis assumes. While the DHL can be defined following Mori's description as a smooth linear change in the degree of physical humanlike similarity, subjective perception of objects along the DHL can be understood in terms of the psychological effects of categorical perception (CP) 7. Further behavioral and neuroimaging investigations of category processing and CP along the DHL and of the potential influence of the dimension's underlying category structure on affective experience are needed. This protocol therefore focuses on the DHL and allows examination of CP. Based on the protocol presented in the video as an example, issues surrounding the methodology in the protocol and the use in "uncanny" research of stimuli drawn from morph continua to represent the DHL are discussed in the article that accompanies the video. The use of neuroimaging and morph stimuli to represent the DHL in order to disentangle brain regions neurally responsive to physical human-like similarity from those responsive to category change and category processing is briefly illustrated. PMID:23770728

  3. What neuroscience can tell about intuitive processes in the context of perceptual discovery.

    PubMed

    Volz, Kirsten G; von Cramon, D Yves

    2006-12-01

    According to the Oxford English Dictionary, intuition is "the ability to understand or know something immediately, without conscious reasoning." Most people would agree that intuitive responses appear as ideas or feelings that subsequently guide our thoughts and behaviors. It is proposed that people continuously, without conscious attention, recognize patterns in the stream of sensations that impinge upon them. What exactly is being recognized is not clear yet, but we assume that people detect potential content based on only a few aspects of the input (i.e., the gist). The result is a vague perception of coherence which is not explicitly describable but instead embodied in a "gut feeling" or an initial guess, which subsequently biases thought and inquiry. To approach the nature of intuitive processes, we used functional magnetic resonance imaging when participants were working at a modified version of the Waterloo Gestalt Closure Task. Starting from our conceptualization that intuition involves an informed judgment in the context of discovery, we expected activation within the median orbito-frontal cortex (OFC), as this area receives input from all sensory modalities and has been shown to be crucially involved in emotionally driven decisions. Results from a direct contrast between intuitive and nonintuitive judgments, as well as from a parametric analysis, revealed the median OFC, the lateral portion of the amygdala, anterior insula, and ventral occipito-temporal regions to be activated. Based on these findings, we suggest our definition of intuition to be promising and a good starting point for future research on intuitive processes. PMID:17129192

  4. Altered attentional and perceptual processes as indexed by N170 during gaze perception in schizophrenia: Relationship with perceived threat and paranoid delusions.

    PubMed

    Tso, Ivy F; Calwas, Anita M; Chun, Jinsoo; Mueller, Savanna A; Taylor, Stephan F; Deldin, Patricia J

    2015-08-01

    Using gaze information to orient attention and guide behavior is critical to social adaptation. Previous studies have suggested that abnormal gaze perception in schizophrenia (SCZ) may originate in abnormal early attentional and perceptual processes and may be related to paranoid symptoms. Using event-related brain potentials (ERPs), this study investigated altered early attentional and perceptual processes during gaze perception and their relationship to paranoid delusions in SCZ. Twenty-eight individuals with SCZ or schizoaffective disorder and 32 demographically matched healthy controls (HCs) completed a gaze-discrimination task with face stimuli varying in gaze direction (direct, averted), head orientation (forward, deviated), and emotion (neutral, fearful). ERPs were recorded during the task. Participants rated experienced threat from each face after the task. Participants with SCZ were as accurate as, though slower than, HCs on the task. Participants with SCZ displayed enlarged N170 responses over the left hemisphere to averted gaze presented in fearful relative to neutral faces, indicating a heightened encoding sensitivity to faces signaling external threat. This abnormality was correlated with increased perceived threat and paranoid delusions. Participants with SCZ also showed a reduction of N170 modulation by head orientation (normally increased amplitude to deviated faces relative to forward faces), suggesting less integration of contextual cues of head orientation in gaze perception. The psychophysiological deviations observed during gaze discrimination in SCZ underscore the role of early attentional and perceptual abnormalities in social information processing and paranoid symptoms of SCZ. PMID:25894438

  5. Low-complexity perceptual post-processing of MPEG-4 sequences

    NASA Astrophysics Data System (ADS)

    Jung, Joel; Le Maguet, Yann; Gobert, Jean; Delcorso, Sandra

    2003-05-01

    This paper presents FaDA (Fast Deblocking Algorithm), a low complexity post-processing algorithm that improves the visual quality of MPEG-4 low bit rate videos displayed on mobile devices. Most of the algorithms proposed up to now to enhance the visual quality after the decoder are far too complex for this kind of devices, and unfortunately deblocking algorithms efficiency is tightly related to their complexity. FaDA achieves complexity reduction while maintaining quality thanks to two principles: 1- The artifact correction is driven by Human Visual System properties, 2- A particular attention has been paid on the design of the most consuming parts of the algorithm, following implementation guidelines. We present a complete complexity evaluation that considers not only computational charge, but also number and locality of memory accesses, data dependency, and internal data size requirements. Critical steps of the algorithm were implemented in C and optimized on a TriMedia DSP. The complexity evaluation reveals a reduction by a factor ranging between 2 and 3.5, compared to the reference MPEG-4 informative deblocking, depending on architecture and implementation. Extensive subjective tests performed on both mobile LCD screen and high resolution monitor show that FaDA average visual quality is equivalent to the reference algorithm.

  6. Different Stages, Different Signals: The Modulating Effect of Cognitive Conflict on Subsequent Processing

    PubMed Central

    Zhang, Li; Lu, Qingyun; Xue, Song

    2016-01-01

    The present study used event-related potentials (ERPs) to investigate the function of signals induced by cognitive conflict during the detection stage and the resolution stage of perceptual processing. The study used a combination of the Stroop task and an affective priming task to examine the conflict priming effect when the stimulus onset asynchrony (SOA) was 200 ms or 800 ms. Behavioral results showed that the RTs were shorter for positive targets following congruent primes relative to incongruent primes, and for negative targets following incongruent primes relative to congruent primes when the SOA was 200 ms. ERP results showed that the N2 amplitudes (200–300 ms) for incongruent stimuli were significantly larger than for congruent stimuli in the Stroop task, which indicated a significant conflict effect. Moreover, the N400 amplitudes (500–700 ms) for positive targets after congruent primes were significantly lower than those after incongruent primes when the SOA was 200 ms, which showed a significant negative priming effect. While the SOA was 800 ms, behavioral results showed that the RTs were shorter for positive targets following incongruent primes relative to congruent primes. ERP results showed that the N2 amplitudes (200–300 ms) for incongruent stimuli were significantly larger than for congruent stimuli in the Stroop task, which indicated a significant conflict effect. The N400 amplitudes (1100–1300 ms) for the negative targets after congruent primes were significantly lower than those after incongruent primes when the SOA was 800 ms, which showed a significant positive priming effect. The results demonstrated that the functions of signals induced by cognitive conflict were reversed in two different cognitive processing stages. PMID:27636368

  7. Different Stages, Different Signals: The Modulating Effect of Cognitive Conflict on Subsequent Processing.

    PubMed

    Pan, Fada; Shi, Liang; Zhang, Li; Lu, Qingyun; Xue, Song

    2016-01-01

    The present study used event-related potentials (ERPs) to investigate the function of signals induced by cognitive conflict during the detection stage and the resolution stage of perceptual processing. The study used a combination of the Stroop task and an affective priming task to examine the conflict priming effect when the stimulus onset asynchrony (SOA) was 200 ms or 800 ms. Behavioral results showed that the RTs were shorter for positive targets following congruent primes relative to incongruent primes, and for negative targets following incongruent primes relative to congruent primes when the SOA was 200 ms. ERP results showed that the N2 amplitudes (200-300 ms) for incongruent stimuli were significantly larger than for congruent stimuli in the Stroop task, which indicated a significant conflict effect. Moreover, the N400 amplitudes (500-700 ms) for positive targets after congruent primes were significantly lower than those after incongruent primes when the SOA was 200 ms, which showed a significant negative priming effect. While the SOA was 800 ms, behavioral results showed that the RTs were shorter for positive targets following incongruent primes relative to congruent primes. ERP results showed that the N2 amplitudes (200-300 ms) for incongruent stimuli were significantly larger than for congruent stimuli in the Stroop task, which indicated a significant conflict effect. The N400 amplitudes (1100-1300 ms) for the negative targets after congruent primes were significantly lower than those after incongruent primes when the SOA was 800 ms, which showed a significant positive priming effect. The results demonstrated that the functions of signals induced by cognitive conflict were reversed in two different cognitive processing stages. PMID:27636368

  8. The perceptual processing capacity of summary statistics between and within feature dimensions

    PubMed Central

    Attarha, Mouna; Moore, Cathleen M.

    2015-01-01

    The simultaneous–sequential method was used to test the processing capacity of statistical summary representations both within and between feature dimensions. Sixteen gratings varied with respect to their size and orientation. In Experiment 1, the gratings were equally divided into four separate smaller sets, one of which with a mean size that was larger or smaller than the other three sets, and one of which with a mean orientation that was tilted more leftward or rightward. The task was to report the mean size and orientation of the oddball sets. This therefore required four summary representations for size and another four for orientation. The sets were presented at the same time in the simultaneous condition or across two temporal frames in the sequential condition. Experiment 1 showed evidence of a sequential advantage, suggesting that the system may be limited with respect to establishing multiple within-feature summaries. Experiment 2 eliminates the possibility that some aspect of the task, other than averaging, was contributing to this observed limitation. In Experiment 3, the same 16 gratings appeared as one large superset, and therefore the task only required one summary representation for size and another one for orientation. Equal simultaneous–sequential performance indicated that between-feature summaries are capacity free. These findings challenge the view that within-feature summaries drive a global sense of visual continuity across areas of the peripheral visual field, and suggest a shift in focus to seeking an understanding of how between-feature summaries in one area of the environment control behavior. PMID:26360153

  9. Mid-level perceptual features distinguish objects of different real-world sizes.

    PubMed

    Long, Bria; Konkle, Talia; Cohen, Michael A; Alvarez, George A

    2016-01-01

    Understanding how perceptual and conceptual representations are connected is a fundamental goal of cognitive science. Here, we focus on a broad conceptual distinction that constrains how we interact with objects--real-world size. Although there appear to be clear perceptual correlates for basic-level categories (apples look like other apples, oranges look like other oranges), the perceptual correlates of broader categorical distinctions are largely unexplored, i.e., do small objects look like other small objects? Because there are many kinds of small objects (e.g., cups, keys), there may be no reliable perceptual features that distinguish them from big objects (e.g., cars, tables). Contrary to this intuition, we demonstrated that big and small objects have reliable perceptual differences that can be extracted by early stages of visual processing. In a series of visual search studies, participants found target objects faster when the distractor objects differed in real-world size. These results held when we broadly sampled big and small objects, when we controlled for low-level features and image statistics, and when we reduced objects to texforms--unrecognizable textures that loosely preserve an object's form. However, this effect was absent when we used more basic textures. These results demonstrate that big and small objects have reliably different mid-level perceptual features, and suggest that early perceptual information about broad-category membership may influence downstream object perception, recognition, and categorization processes. PMID:26709591

  10. Children With ADHD Show Impairments in Multiple Stages of Information Processing in a Stroop Task: An ERP Study.

    PubMed

    Kóbor, Andrea; Takács, Ádám; Bryce, Donna; Szűcs, Dénes; Honbolygó, Ferenc; Nagy, Péter; Csépe, Valéria

    2015-01-01

    This study investigated the role of impaired inhibitory control as a factor underlying attention deficit hyperactivity disorder (ADHD). Children with ADHD and typically developing children completed an animal Stroop task while electroencephalogram (EEG) was recorded. The lateralized readiness potential and event-related brain potentials associated with perceptual and conflict processing were analyzed. Children with ADHD were slower to give correct responses irrespective of congruency, and slower to prepare correct responses in the incongruent condition. This delay could result from enhanced effort allocation at earlier processing stages, indicated by differences in P1, N1, and conflict sustained potential. Results suggest multiple deficits in information processing rather than a specific response inhibition impairment. PMID:26421914

  11. Interocular transfer of perceptual skills after sleep.

    PubMed

    Deliens, Gaétane; Schmitz, Rémy; Peigneux, Philippe

    2014-01-24

    Several studies suggest that sleep improves perceptual skills in the visual texture discrimination task (TDT). Here we report that besides consolidation, sleep also generalizes the learned perceptual abilities to the untrained eye. Healthy volunteers (n = 32) were trained on the TDT, in which they had to discriminate between horizontal and vertical target textures briefly presented in the periphery of the visual field (left upper quadrant). After a 10-hr interval filled with either sleep or wakefulness, they were retested first on the trained eye in the trained quadrant and then on the untrained eye and quadrant. In line with prior findings, visual discrimination was globally higher after sleep than after wakefulness, as compared to performance levels at the end of training. Furthermore, discrimination performance was significantly improved only in the sleep condition for the untrained eye in the same quadrant, but also showed a trend to generalize to the untrained eye and untrained quadrant. Our results suggest that sleep-dependent perceptual skills continue developing at a later visual-process stage than the V1 area, where learning is not monocular anymore.

  12. How "Central" Is Central Coherence?: Preliminary Evidence on the Link between Conceptual and Perceptual Processing in Children with Autism

    ERIC Educational Resources Information Center

    Lopez, Beatriz; Leekam, Susan R.; Arts, Gerda R. J.

    2008-01-01

    This study aimed to test the assumption drawn from weak central coherence theory that a central cognitive mechanism is responsible for integrating information at both conceptual and perceptual levels. A visual semantic memory task and a face recognition task measuring use of holistic information were administered to 15 children with autism and 16…

  13. Effects of Semantic Context and Feedback on Perceptual Learning of Speech Processed through an Acoustic Simulation of a Cochlear Implant

    ERIC Educational Resources Information Center

    Loebach, Jeremy L.; Pisoni, David B.; Svirsky, Mario A.

    2010-01-01

    The effect of feedback and materials on perceptual learning was examined in listeners with normal hearing who were exposed to cochlear implant simulations. Generalization was most robust when feedback paired the spectrally degraded sentences with their written transcriptions, promoting mapping between the degraded signal and its acoustic-phonetic…

  14. Hydrogen production: two stage processes for waste degradation.

    PubMed

    Gómez, X; Fernández, C; Fierro, J; Sánchez, M E; Escapa, A; Morán, A

    2011-09-01

    The dark fermentation process generates hydrogen by biological means. It presents two main advantages: fulfilling requirements for mild operational conditions and gaining benefit from the residual biomass. The process itself may be seen as a pre-treatment step in a complete stabilisation chain, with the aim of attaining the valorisation of residual biomass. However, increasing the yield of H2 production is an imperative task. In this manuscript, a review of recent work in the field of fermentative hydrogen production is presented. As dark fermentation has a maximum yield of 33% (on sugars), a description is also presented of possible second stage processes for the degradation of dark fermentation effluents. Alternatives considered were photofermentation and bioelectrochemical systems (BES) as processes capable of converting fermentation sub-products into H2. Anaerobic digestion as a final stabilisation stage was also considered owing to the wide application of this technology in the treatment of bio-wastes.

  15. Deciphering the pathogenesis of tendinopathy: a three-stages process

    PubMed Central

    2010-01-01

    Our understanding of the pathogenesis of "tendinopathy" is based on fragmented evidences like pieces of a jigsaw puzzle. We propose a "failed healing theory" to knit these fragments together, which can explain previous observations. We also propose that albeit "overuse injury" and other insidious "micro trauma" may well be primary triggers of the process, "tendinopathy" is not an "overuse injury" per se. The typical clinical, histological and biochemical presentation relates to a localized chronic pain condition which may lead to tendon rupture, the latter attributed to mechanical weakness. Characterization of pathological "tendinotic" tissues revealed coexistence of collagenolytic injuries and an active healing process, focal hypervascularity and tissue metaplasia. These observations suggest a failed healing process as response to a triggering injury. The pathogenesis of tendinopathy can be described as a three stage process: injury, failed healing and clinical presentation. It is likely that some of these "initial injuries" heal well and we speculate that predisposing intrinsic or extrinsic factors may be involved. The injury stage involves a progressive collagenolytic tendon injury. The failed healing stage mainly refers to prolonged activation and failed resolution of the normal healing process. Finally, the matrix disturbances, increased focal vascularity and abnormal cytokine profiles contribute to the clinical presentations of chronic tendon pain or rupture. With this integrative pathogenesis theory, we can relate the known manifestations of tendinopathy and point to the "missing links". This model may guide future research on tendinopathy, until we could ultimately decipher the complete pathogenesis process and provide better treatments. PMID:21144004

  16. Perceptual grouping across eccentricity.

    PubMed

    Tannazzo, Teresa; Kurylo, Daniel D; Bukhari, Farhan

    2014-10-01

    Across the visual field, progressive differences exist in neural processing as well as perceptual abilities. Expansion of stimulus scale across eccentricity compensates for some basic visual capacities, but not for high-order functions. It was hypothesized that as with many higher-order functions, perceptual grouping ability should decline across eccentricity. To test this prediction, psychophysical measurements of grouping were made across eccentricity. Participants indicated the dominant grouping of dot grids in which grouping was based upon luminance, motion, orientation, or proximity. Across trials, the organization of stimuli was systematically decreased until perceived grouping became ambiguous. For all stimulus features, grouping ability remained relatively stable until 40°, beyond which thresholds significantly elevated. The pattern of change across eccentricity varied across stimulus feature, in which stimulus scale, dot size, or stimulus size interacted with eccentricity effects. These results demonstrate that perceptual grouping of such stimuli is not reliant upon foveal viewing, and suggest that selection of dominant grouping patterns from ambiguous displays operates similarly across much of the visual field.

  17. Rapid distributed fronto-parieto-occipital processing stages during working memory in humans.

    PubMed

    Halgren, E; Boujon, C; Clarke, J; Wang, C; Chauvel, P

    2002-07-01

    Cortical potentials were recorded from implanted electrodes during a difficult working memory task requiring rapid storage, modification and retrieval of multiple memoranda. Synchronous event-related potentials were generated in distributed occipital, parietal, Rolandic and prefrontal sites beginning approximately 130 ms after stimulus onset and continuing for >500 ms. Coherent phase-locked, event-related oscillations supported interaction between these dorsal stream structures throughout the task period. The Rolandic structures generated early as well as sustained potentials to sensory stimuli in the absence of movement. Activation peaks and phase lags between synaptic populations suggested that perceptual processing occurred exclusively in the visual association cortex from approximately 90 to 130 ms, with its results projected to fronto-parietal areas for interpretation from approximately 130 to 280 ms. The direction of interaction then appeared to reverse from approximately 300 to 400 ms, consistent with mental arithmetic being performed by fronto-parietal areas operating upon a visual scratch pad in the dorsolateral occipital cortex. A second reversal, from approximately 420 to 600 ms, may have represented an updating of memoranda stored in fronto-parietal sites. Lateralized perisylvian oscillations suggested an articulatory loop. Anterior cingulate activity was evoked by feedback signals indicating errors. These results indicate how a fronto-centro-parietal 'central executive' might interact with an occipital visual scratch pad, perisylvian articulatory loop and limbic monitor to implement the sequential stages of a complex mental operation.

  18. Optimization of a novel enzyme treatment process for early-stage processing of sheepskins.

    PubMed

    Lim, Y F; Bronlund, J E; Allsop, T F; Shilton, A N; Edmonds, R L

    2010-01-01

    An enzyme treatment process for early-stage processing of sheepskins has been previously reported by the Leather and Shoe Research Association of New Zealand (LASRA) as an alternative to current industry operations. The newly developed process had marked benefits over conventional processing in terms of a lowered energy usage (73%), processing time (47%) as well as water use (49%), but had been developed as a "proof of principle''. The objective of this work was to develop the process further to a stage ready for adoption by industry. Mass balancing was used to investigate potential modifications for the process based on the understanding developed from a detailed analysis of preliminary design trials. Results showed that a configuration utilising a 2 stage counter-current system for the washing stages and segregation and recycling of enzyme float prior to dilution in the neutralization stage was a significant improvement. Benefits over conventional processing include a reduction of residual TDS by 50% at the washing stages and 70% savings on water use overall. Benefits over the un-optimized LASRA process are reduction of solids in product after enzyme treatment and neutralization stages by 30%, additional water savings of 21%, as well as 10% savings of enzyme usage. PMID:20861557

  19. Perceptual learning: top to bottom.

    PubMed

    Amitay, Sygal; Zhang, Yu-Xuan; Jones, Pete R; Moore, David R

    2014-06-01

    Perceptual learning has traditionally been portrayed as a bottom-up phenomenon that improves encoding or decoding of the trained stimulus. Cognitive skills such as attention and memory are thought to drive, guide and modulate learning but are, with notable exceptions, not generally considered to undergo changes themselves as a result of training with simple perceptual tasks. Moreover, shifts in threshold are interpreted as shifts in perceptual sensitivity, with no consideration for non-sensory factors (such as response bias) that may contribute to these changes. Accumulating evidence from our own research and others shows that perceptual learning is a conglomeration of effects, with training-induced changes ranging from the lowest (noise reduction in the phase locking of auditory signals) to the highest (working memory capacity) level of processing, and includes contributions from non-sensory factors that affect decision making even on a "simple" auditory task such as frequency discrimination. We discuss our emerging view of learning as a process that increases the signal-to-noise ratio associated with perceptual tasks by tackling noise sources and inefficiencies that cause performance bottlenecks, and present some implications for training populations other than young, smart, attentive and highly-motivated college students.

  20. Working memory-driven attention improves spatial resolution: Support for perceptual enhancement.

    PubMed

    Pan, Yi; Luo, Qianying; Cheng, Min

    2016-08-01

    Previous research has indicated that attention can be biased toward those stimuli matching the contents of working memory and thereby facilitates visual processing at the location of the memory-matching stimuli. However, whether this working memory-driven attentional modulation takes place on early perceptual processes remains unclear. Our present results showed that working memory-driven attention improved identification of a brief Landolt target presented alone in the visual field. Because the suprathreshold target appeared without any external noise added (i.e., no distractors or masks), the results suggest that working memory-driven attention enhances the target signal at early perceptual stages of visual processing. Furthermore, given that performance in the Landolt target identification task indexes spatial resolution, this attentional facilitation indicates that working memory-driven attention can boost early perceptual processing via enhancement of spatial resolution at the attended location.

  1. Crew Launch Vehicle (CLV) Upper Stage Configuration Selection Process

    NASA Technical Reports Server (NTRS)

    Davis, Daniel J.; Coook, Jerry R.

    2006-01-01

    changed since the CLV Project's inception, the USE design has remained essentially a clean-sheet approach. Although a clean-sheet upper stage design inherently carries more risk than a modified design, it does offer many advantages: a design for increased reliability; built-in extensibility to allow for commonality/growth without major redesign; and incorporation of state-of-the-art materials, hardware, and design, fabrication, and test techniques and processes to facilitate a potentially better, more reliable system. Because consideration was given in the ESAS to both clean-sheet and modified USE designs, this paper will highlight the advantages and disadvantages of both approaches and provide a detailed discussion of trades/selections made that led to the final upper stage configuration.

  2. Conceptual and perceptual encoding instructions differently affect event recall.

    PubMed

    García-Bajos, Elvira; Migueles, Malen; Aizpurua, Alaitz

    2014-11-01

    When recalling an event, people usually retrieve the main facts and a reduced proportion of specific details. The objective of this experiment was to study the effects of conceptually and perceptually driven encoding in the recall of conceptual and perceptual information of an event. The materials selected for the experiment were two movie trailers. To enhance the encoding instructions, after watching the first trailer participants answered conceptual or perceptual questions about the event, while a control group answered general knowledge questions. After watching the second trailer, all of the participants completed a closed-ended recall task consisting of conceptual and perceptual items. Conceptual information was better recalled than perceptual details and participants made more perceptual than conceptual commission errors. Conceptually driven processing enhanced the recall of conceptual information, while perceptually driven processing not only did not improve the recall of descriptive details, but also damaged the standard conceptual/perceptual recall relationship.

  3. Perceptual Repetition Blindness Effects

    NASA Technical Reports Server (NTRS)

    Hochhaus, Larry; Johnston, James C.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    The phenomenon of repetition blindness (RB) may reveal a new limitation on human perceptual processing. Recently, however, researchers have attributed RB to post-perceptual processes such as memory retrieval and/or reporting biases. The standard rapid serial visual presentation (RSVP) paradigm used in most RB studies is, indeed, open to such objections. Here we investigate RB using a "single-frame" paradigm introduced by Johnston and Hale (1984) in which memory demands are minimal. Subjects made only a single judgement about whether one masked target word was the same or different than a post-target probe. Confidence ratings permitted use of signal detection methods to assess sensitivity and bias effects. In the critical condition for RB a precue of the post-target word was provided prior to the target stimulus (identity precue), so that the required judgement amounted to whether the target did or did not repeat the precue word. In control treatments, the precue was either an unrelated word or a dummy.

  4. Perceptual learning of acoustic noise generates memory-evoked potentials.

    PubMed

    Andrillon, Thomas; Kouider, Sid; Agus, Trevor; Pressnitzer, Daniel

    2015-11-01

    Experience continuously imprints on the brain at all stages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show that the perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever a memory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics.

  5. Multiple spatial frequency channels in human visual perceptual memory.

    PubMed

    Nemes, V A; Whitaker, D; Heron, J; McKeefry, D J

    2011-12-01

    Current models of short-term visual perceptual memory invoke mechanisms that are closely allied to low-level perceptual discrimination mechanisms. The purpose of this study was to investigate the extent to which human visual perceptual memory for spatial frequency is based upon multiple, spatially tuned channels similar to those found in the earliest stages of visual processing. To this end we measured how performance on a delayed spatial frequency discrimination paradigm was affected by the introduction of interfering or 'memory masking' stimuli of variable spatial frequency during the delay period. Masking stimuli were shown to induce shifts in the points of subjective equality (PSE) when their spatial frequencies were within a bandwidth of 1.2 octaves of the reference spatial frequency. When mask spatial frequencies differed by more than this value, there was no change in the PSE from baseline levels. This selective pattern of masking was observed for different spatial frequencies and demonstrates the existence of multiple, spatially tuned mechanisms in visual perceptual memory. Memory masking effects were also found to occur for horizontal separations of up to 6 deg between the masking and test stimuli and lacked any orientation selectivity. These findings add further support to the view that low-level sensory processing mechanisms form the basis for the retention of spatial frequency information in perceptual memory. However, the broad range of transfer of memory masking effects across spatial location and other dimensions indicates more long range, long duration interactions between spatial frequency channels that are likely to rely contributions from neural processes located in higher visual areas.

  6. Beyond Perceptual Symbols: A Call for Representational Pluralism

    ERIC Educational Resources Information Center

    Dove, Guy

    2009-01-01

    Recent evidence from cognitive neuroscience suggests that certain cognitive processes employ perceptual representations. Inspired by this evidence, a few researchers have proposed that cognition is inherently perceptual. They have developed an innovative theoretical approach that rests on the notion of perceptual simulation and marshaled several…

  7. Some Perceptual Prerequisites for Reading.

    ERIC Educational Resources Information Center

    Frith, Uta; Vogel, Juliet M.

    The two chapters of this monograph deal with the issue of the existence of a perceptual grammar that influences reading proficiency, particularly initial reading proficiency. The first chapter indicates the importance of studying reading and writing in terms of readers' and writers' knowledge of visuo-spatial processing rules. It discusses…

  8. Perceptual learning: toward a comprehensive theory.

    PubMed

    Watanabe, Takeo; Sasaki, Yuka

    2015-01-01

    Visual perceptual learning (VPL) is long-term performance increase resulting from visual perceptual experience. Task-relevant VPL of a feature results from training of a task on the feature relevant to the task. Task-irrelevant VPL arises as a result of exposure to the feature irrelevant to the trained task. At least two serious problems exist. First, there is the controversy over which stage of information processing is changed in association with task-relevant VPL. Second, no model has ever explained both task-relevant and task-irrelevant VPL. Here we propose a dual plasticity model in which feature-based plasticity is a change in a representation of the learned feature, and task-based plasticity is a change in processing of the trained task. Although the two types of plasticity underlie task-relevant VPL, only feature-based plasticity underlies task-irrelevant VPL. This model provides a new comprehensive framework in which apparently contradictory results could be explained.

  9. Perceptual effects of scene context on object identification.

    PubMed

    De Graef, P; Christiaens, D; d'Ydewalle, G

    1990-01-01

    In a number of studies the context provided by a real-world scene has been claimed to have a mandatory, perceptual effect on the identification of individual objects in such a scene. This claim has provided a basis for challenging widely accepted data-driven models of visual perception in order to advocate alternative models with an outspoken top-down character. The present paper offers a review of the evidence to demonstrate that the observed scene-context effects may be the product of post-perceptual and task-dependent guessing strategies. A new research paradigm providing an on-line measure of genuine perceptual effects of context on object identification is proposed. First-fixation durations for objects incidentally fixated during the free exploration of real-world scenes are shown to increase when the objects are improbable in the scene or violate certain aspects of their typical spatial appearance in it. These effects of contextual violations are shown to emerge only at later stages of scene exploration, contrary to the notion of schema-driven scene perception effective from the very first scene fixation. In addition, evidence is reported in support of the existence of a facilitatory component in scene-context effects. This is taken to indicate that the context directly affects the ease of perceptual object processing and does not merely serve as a framework for checking the plausibility of the output of perceptual processes. Finally, our findings are situated against other contrasting results. Some future research questions are high-lighted.

  10. Assess sleep stage by modern signal processing techniques.

    PubMed

    Wu, Hau-tieng; Talmon, Ronen; Lo, Yu-Lun

    2015-04-01

    In this paper, two modern adaptive signal processing techniques, empirical intrinsic geometry and synchrosqueezing transform, are applied to quantify different dynamical features of the respiratory and electroencephalographic signals. We show that the proposed features are theoretically rigorously supported, as well as capture the sleep information hidden inside the signals. The features are used as input to multiclass support vector machines with the radial basis function to automatically classify sleep stages. The effectiveness of the classification based on the proposed features is shown to be comparable to human expert classification-the proposed classification of awake, REM, N1, N2, and N3 sleeping stages based on the respiratory signal (resp. respiratory and EEG signals) has the overall accuracy 81.7% (resp. 89.3%) in the relatively normal subject group. In addition, by examining the combination of the respiratory signal with the electroencephalographic signal, we conclude that the respiratory signal consists of ample sleep information, which supplements to the information stored in the electroencephalographic signal.

  11. Two-stage process for conversion of alkanes to gasoline

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1989-08-22

    This patent describes an improvement in a two-stage process for upgrading hydrocarbons in at least four reaction zones cooperating to produce gasoline range hydrocarbons from lower alkanes. The reaction zones comprising first reaction zone to crack gas oil range hydrocarbons utilizing a large pore cracking catalyst, a second reaction zone in which the large pore catalyst is oxidatively regenerated, a third reaction zone in which an external catalyst cooler autogeneously cools regenerated catalyst by dehydrogenation of the lower alkane stream to produce an olefinic effluent, and a fourth reaction zone in which the olefinic effluent is oligomerized to the gasoline range hydrocarbons. The improvement comprising: a first stage, comprising utilizing excess heat from the second reaction zone: contacting the hot fluid catalytic cracking catalyst with C/sub 3//sup +/ alkanes in the third reaction zone to provide conversion of the alkanes to olefins which leave the third reaction zone as the olefinic effluent separated from catalyst; returning a specified amount of separate fluid catalytic cracking catalyst from the third reaction zone directly to the first or second reaction zone; a second state comprising passing the olefinic effluent from the third reaction zone to a fourth reaction zone for oligomerizing olefins to gasoline range hydrocarbons contacting the olefinic effluent with a medium pore zeolite catalyst effective; recovering a gasoline range hydrocarbon stream from the effluent of the fourth reaction zone.

  12. Dissociated Mechanisms of Extracting Perceptual Information into Visual Working Memory

    PubMed Central

    Gao, Zaifeng; Li, Jie; Yin, Jun; Shen, Mowei

    2010-01-01

    Background The processing mechanisms of visual working memory (VWM) have been extensively explored in the recent decade. However, how the perceptual information is extracted into VWM remains largely unclear. The current study investigated this issue by testing whether the perceptual information was extracted into VWM via an integrated-object manner so that all the irrelevant information would be extracted (object hypothesis), or via a feature-based manner so that only the target-relevant information would be extracted (feature hypothesis), or via an analogous processing manner as that in visual perception (analogy hypothesis). Methodology/Principal Findings High-discriminable information which is processed at the parallel stage of visual perception and fine-grained information which is processed via focal attention were selected as the representatives of perceptual information. The analogy hypothesis predicted that whereas high-discriminable information is extracted into VWM automatically, fine-grained information will be extracted only if it is task-relevant. By manipulating the information type of the irrelevant dimension in a change-detection task, we found that the performance was affected and the ERP component N270 was enhanced if a change between the probe and the memorized stimulus consisted of irrelevant high-discriminable information, but not if it consisted of irrelevant fine-grained information. Conclusions/Significance We conclude that dissociated extraction mechanisms exist in VWM for information resolved via dissociated processes in visual perception (at least for the information tested in the current study), supporting the analogy hypothesis. PMID:21170315

  13. The role of bottom-up processing in perceptual categorization by 3- to 4-month-old infants: simulations and data.

    PubMed

    French, Robert M; Mareschal, Denis; Mermillod, Martial; Quinn, Paul C

    2004-09-01

    Disentangling bottom-up and top-down processing in adult category learning is notoriously difficult. Studying category learning in infancy provides a simple way of exploring category learning while minimizing the contribution of top-down information. Three- to 4-month-old infants presented with cat or dog images will form a perceptual category representation for cat that excludes dogs and for dog that includes cats. The authors argue that an inclusion relationship in the distribution of features in the images explains the asymmetry. Using computational modeling and behavioral testing, the authors show that the asymmetry can be reversed or removed by using stimulus images that reverse or remove the inclusion relationship. The findings suggest that categorization of nonhuman animal images by young infants is essentially a bottom-up process.

  14. The cerebellum and visual perceptual learning: evidence from a motion extrapolation task.

    PubMed

    Deluca, Cristina; Golzar, Ashkan; Santandrea, Elisa; Lo Gerfo, Emanuele; Eštočinová, Jana; Moretto, Giuseppe; Fiaschi, Antonio; Panzeri, Marta; Mariotti, Caterina; Tinazzi, Michele; Chelazzi, Leonardo

    2014-09-01

    Visual perceptual learning is widely assumed to reflect plastic changes occurring along the cerebro-cortical visual pathways, including at the earliest stages of processing, though increasing evidence indicates that higher-level brain areas are also involved. Here we addressed the possibility that the cerebellum plays an important role in visual perceptual learning. Within the realm of motor control, the cerebellum supports learning of new skills and recalibration of motor commands when movement execution is consistently perturbed (adaptation). Growing evidence indicates that the cerebellum is also involved in cognition and mediates forms of cognitive learning. Therefore, the obvious question arises whether the cerebellum might play a similar role in learning and adaptation within the perceptual domain. We explored a possible deficit in visual perceptual learning (and adaptation) in patients with cerebellar damage using variants of a novel motion extrapolation, psychophysical paradigm. Compared to their age- and gender-matched controls, patients with focal damage to the posterior (but not the anterior) cerebellum showed strongly diminished learning, in terms of both rate and amount of improvement over time. Consistent with a double-dissociation pattern, patients with focal damage to the anterior cerebellum instead showed more severe clinical motor deficits, indicative of a distinct role of the anterior cerebellum in the motor domain. The collected evidence demonstrates that a pure form of slow-incremental visual perceptual learning is crucially dependent on the intact cerebellum, bearing the notion that the human cerebellum acts as a learning device for motor, cognitive and perceptual functions. We interpret the deficit in terms of an inability to fine-tune predictive models of the incoming flow of visual perceptual input over time. Moreover, our results suggest a strong dissociation between the role of different portions of the cerebellum in motor versus

  15. Basic auditory processing and sensitivity to prosodic structure in children with specific language impairments: a new look at a perceptual hypothesis

    PubMed Central

    Cumming, Ruth; Wilson, Angela; Goswami, Usha

    2015-01-01

    Children with specific language impairments (SLIs) show impaired perception and production of spoken language, and can also present with motor, auditory, and phonological difficulties. Recent auditory studies have shown impaired sensitivity to amplitude rise time (ART) in children with SLIs, along with non-speech rhythmic timing difficulties. Linguistically, these perceptual impairments should affect sensitivity to speech prosody and syllable stress. Here we used two tasks requiring sensitivity to prosodic structure, the DeeDee task and a stress misperception task, to investigate this hypothesis. We also measured auditory processing of ART, rising pitch and sound duration, in both speech (“ba”) and non-speech (tone) stimuli. Participants were 45 children with SLI aged on average 9 years and 50 age-matched controls. We report data for all the SLI children (N = 45, IQ varying), as well as for two independent SLI subgroupings with intact IQ. One subgroup, “Pure SLI,” had intact phonology and reading (N = 16), the other, “SLI PPR” (N = 15), had impaired phonology and reading. Problems with syllable stress and prosodic structure were found for all the group comparisons. Both sub-groups with intact IQ showed reduced sensitivity to ART in speech stimuli, but the PPR subgroup also showed reduced sensitivity to sound duration in speech stimuli. Individual differences in processing syllable stress were associated with auditory processing. These data support a new hypothesis, the “prosodic phrasing” hypothesis, which proposes that grammatical difficulties in SLI may reflect perceptual difficulties with global prosodic structure related to auditory impairments in processing amplitude rise time and duration. PMID:26217286

  16. Basic auditory processing and sensitivity to prosodic structure in children with specific language impairments: a new look at a perceptual hypothesis.

    PubMed

    Cumming, Ruth; Wilson, Angela; Goswami, Usha

    2015-01-01

    Children with specific language impairments (SLIs) show impaired perception and production of spoken language, and can also present with motor, auditory, and phonological difficulties. Recent auditory studies have shown impaired sensitivity to amplitude rise time (ART) in children with SLIs, along with non-speech rhythmic timing difficulties. Linguistically, these perceptual impairments should affect sensitivity to speech prosody and syllable stress. Here we used two tasks requiring sensitivity to prosodic structure, the DeeDee task and a stress misperception task, to investigate this hypothesis. We also measured auditory processing of ART, rising pitch and sound duration, in both speech ("ba") and non-speech (tone) stimuli. Participants were 45 children with SLI aged on average 9 years and 50 age-matched controls. We report data for all the SLI children (N = 45, IQ varying), as well as for two independent SLI subgroupings with intact IQ. One subgroup, "Pure SLI," had intact phonology and reading (N = 16), the other, "SLI PPR" (N = 15), had impaired phonology and reading. Problems with syllable stress and prosodic structure were found for all the group comparisons. Both sub-groups with intact IQ showed reduced sensitivity to ART in speech stimuli, but the PPR subgroup also showed reduced sensitivity to sound duration in speech stimuli. Individual differences in processing syllable stress were associated with auditory processing. These data support a new hypothesis, the "prosodic phrasing" hypothesis, which proposes that grammatical difficulties in SLI may reflect perceptual difficulties with global prosodic structure related to auditory impairments in processing amplitude rise time and duration. PMID:26217286

  17. Rehabilitation of face-processing skills in an adolescent with prosopagnosia: Evaluation of an online perceptual training programme.

    PubMed

    Bate, Sarah; Bennetts, Rachel; Mole, Joseph A; Ainge, James A; Gregory, Nicola J; Bobak, Anna K; Bussunt, Amanda

    2015-01-01

    In this paper we describe the case of EM, a female adolescent who acquired prosopagnosia following encephalitis at the age of eight. Initial neuropsychological and eye-movement investigations indicated that EM had profound difficulties in face perception as well as face recognition. EM underwent 14 weeks of perceptual training in an online programme that attempted to improve her ability to make fine-grained discriminations between faces. Following training, EM's face perception skills had improved, and the effect generalised to untrained faces. Eye-movement analyses also indicated that EM spent more time viewing the inner facial features post-training. Examination of EM's face recognition skills revealed an improvement in her recognition of personally-known faces when presented in a laboratory-based test, although the same gains were not noted in her everyday experiences with these faces. In addition, EM did not improve on a test assessing the recognition of newly encoded faces. One month after training, EM had maintained the improvement on the eye-tracking test, and to a lesser extent, her performance on the familiar faces test. This pattern of findings is interpreted as promising evidence that the programme can improve face perception skills, and with some adjustments, may at least partially improve face recognition skills.

  18. Rehabilitation of face-processing skills in an adolescent with prosopagnosia: Evaluation of an online perceptual training programme.

    PubMed

    Bate, Sarah; Bennetts, Rachel; Mole, Joseph A; Ainge, James A; Gregory, Nicola J; Bobak, Anna K; Bussunt, Amanda

    2015-01-01

    In this paper we describe the case of EM, a female adolescent who acquired prosopagnosia following encephalitis at the age of eight. Initial neuropsychological and eye-movement investigations indicated that EM had profound difficulties in face perception as well as face recognition. EM underwent 14 weeks of perceptual training in an online programme that attempted to improve her ability to make fine-grained discriminations between faces. Following training, EM's face perception skills had improved, and the effect generalised to untrained faces. Eye-movement analyses also indicated that EM spent more time viewing the inner facial features post-training. Examination of EM's face recognition skills revealed an improvement in her recognition of personally-known faces when presented in a laboratory-based test, although the same gains were not noted in her everyday experiences with these faces. In addition, EM did not improve on a test assessing the recognition of newly encoded faces. One month after training, EM had maintained the improvement on the eye-tracking test, and to a lesser extent, her performance on the familiar faces test. This pattern of findings is interpreted as promising evidence that the programme can improve face perception skills, and with some adjustments, may at least partially improve face recognition skills. PMID:25369318

  19. Negative BOLD response and serotonin concentration within rostral subgenual portion of the anterior cingulate cortex for long-allele carriers during perceptual processing of emotional tasks

    NASA Astrophysics Data System (ADS)

    Hadi, Shamil M.; Siadat, Mohamad R.; Babajani-Feremi, Abbas

    2012-03-01

    We investigated the effect of synaptic serotonin concentration on hemodynamic responses. The stimuli paradigm involved the presentation of fearful and threatening facial expressions to a set of 24 subjects who were either5HTTLPR long- or short-allele carriers (12 of each type in each group). The BOLD signals of the rACC from subjects of each group were averaged to increase the signal-to-noise ratio. We used a Bayesian approach to estimate the parameters of the underlying hemodynamic model. Our results, during this perceptual processing of emotional task, showed a negative BOLD signal in the rACC in the subjects with long-alleles. In contrast, the subjects with short-alleles showed positive BOLD signals in the rACC. These results suggest that high synaptic serotonin concentration in the rACC inhibits neuronal activity in a fashion similar to GABA, and a consequent negative BOLD signal ensues.

  20. Can Attention be Divided Between Perceptual Groups?

    NASA Technical Reports Server (NTRS)

    McCann, Robert S.; Foyle, David C.; Johnston, James C.; Hart, Sandra G. (Technical Monitor)

    1994-01-01

    Previous work using Head-Up Displays (HUDs) suggests that the visual system parses the HUD and the outside world into distinct perceptual groups, with attention deployed sequentially to first one group and then the other. New experiments show that both groups can be processed in parallel in a divided attention search task, even though subjects have just processed a stimulus in one perceptual group or the other. Implications for models of visual attention will be discussed.

  1. Visual prediction and perceptual expertise

    PubMed Central

    Cheung, Olivia S.; Bar, Moshe

    2012-01-01

    Making accurate predictions about what may happen in the environment requires analogies between perceptual input and associations in memory. These elements of predictions are based on cortical representations, but little is known about how these processes can be enhanced by experience and training. On the other hand, studies on perceptual expertise have revealed that the acquisition of expertise leads to strengthened associative processing among features or objects, suggesting that predictions and expertise may be tightly connected. Here we review the behavioral and neural findings regarding the mechanisms involving prediction and expert processing, and highlight important possible overlaps between them. Future investigation should examine the relations among perception, memory and prediction skills as a function of expertise. The knowledge gained by this line of research will have implications for visual cognition research, and will advance our understanding of how the human brain can improve its ability to predict by learning from experience. PMID:22123523

  2. Magnetoencephalographic Signals Identify Stages in Real-Life Decision Processes

    PubMed Central

    Braeutigam, Sven; Stins, John F.; Rose, Steven P. R.; Swithenby, Stephen J.; Ambler, Tim

    2001-01-01

    We used magnetoencephalography (MEG) to study the dynamics of neural responses in eight subjects engaged in shopping for day-to-day items from supermarket shelves. This behavior not only has personal and economic importance but also provides an example of an experience that is both personal and shared between individuals. The shopping experience enables the exploration of neural mechanisms underlying choice based on complex memories. Choosing among different brands of closely related products activated a robust sequence of signals within the first second after the presentation of the choice images. This sequence engaged first the visual cortex (80-100 ms), then as the images were analyzed, predominantly the left temporal regions (310-340 ms). At longer latency, characteristic neural activetion was found in motor speech areas (500-520 ms) for images requiring low salience choices with respect to previous (brand) memory, and in right parietal cortex for high salience choices (850-920 ms). We argue that the neural processes associated with the particular brand-choice stimulus can be separated into identifiable stages through observation of MEG responses and knowledge of functional anatomy. PMID:12018772

  3. The formation of linked perceptual classes.

    PubMed Central

    Fields, Lanny; Matneja, Priya; Varelas, Antonios; Belanich, James; Fitzer, Adrienne; Shamoun, Kim

    2002-01-01

    Multiple-exemplar training with stimuli in four domains induced two new fill-based (A1' and A2') and satellite-image-based (B1' and B2') perceptual classes. Conditional discriminations were established between the endpoints of the A1' and B1' classes as well as the A2' and B2' classes. The emergence of linked perceptual classes was evaluated by the performances occasioned by nine cross-class probes that contained fill variants as samples and satellite variants as comparisons, along with nine other cross-class probes that consisted of satellite variants as samples and fill variants as comparisons. The 18 probes were first presented serially and then concurrently. Class-consistent responding indicated the emergence of linked perceptual classes. Of the linked perceptual classes, 70% emerged during the initial serial test. An additional 20% of the linked perceptual classes emerged during the subsequently presented concurrent test block. Thus, linked perceptual classes emerged on an immediate or delayed basis. Linked perceptual classes, then, share structural and fuctional similarities with equivalence classes, generalized equivalence classes, cross-modal classes, and complex maturally occurring categories, and may clarify processes such as intersensory perception. PMID:12507004

  4. The formation of linked perceptual classes.

    PubMed

    Fields, Lanny; Matneja, Priya; Varelas, Antonios; Belanich, James; Fitzer, Adrienne; Shamoun, Kim

    2002-11-01

    Multiple-exemplar training with stimuli in four domains induced two new fill-based (A1' and A2') and satellite-image-based (B1' and B2') perceptual classes. Conditional discriminations were established between the endpoints of the A1' and B1' classes as well as the A2' and B2' classes. The emergence of linked perceptual classes was evaluated by the performances occasioned by nine cross-class probes that contained fill variants as samples and satellite variants as comparisons, along with nine other cross-class probes that consisted of satellite variants as samples and fill variants as comparisons. The 18 probes were first presented serially and then concurrently. Class-consistent responding indicated the emergence of linked perceptual classes. Of the linked perceptual classes, 70% emerged during the initial serial test. An additional 20% of the linked perceptual classes emerged during the subsequently presented concurrent test block. Thus, linked perceptual classes emerged on an immediate or delayed basis. Linked perceptual classes, then, share structural and fuctional similarities with equivalence classes, generalized equivalence classes, cross-modal classes, and complex maturally occurring categories, and may clarify processes such as intersensory perception.

  5. Confuse your illusion: feedback to early visual cortex contributes to perceptual completion.

    PubMed

    Wokke, Martijn E; Vandenbroucke, Annelinde R E; Scholte, H Steven; Lamme, Victor A F

    2013-01-01

    A striking example of the constructive nature of visual perception is how the human visual system completes contours of occluded objects. To date, it is unclear whether perceptual completion emerges during early stages of visual processing or whether higher-level mechanisms are necessary. To answer this question, we used transcranial magnetic stimulation to disrupt signaling in V1/V2 and in the lateral occipital (LO) area at different moments in time while participants performed a discrimination task involving a Kanizsa-type illusory figure. Results show that both V1/V2 and higher-level visual area LO are critically involved in perceptual completion. However, these areas seem to be involved in an inverse hierarchical fashion, in which the critical time window for V1/V2 follows that for LO. These results are in line with the growing evidence that feedback to V1/V2 contributes to perceptual completion. PMID:23228938

  6. Prior expectations facilitate metacognition for perceptual decision.

    PubMed

    Sherman, M T; Seth, A K; Barrett, A B; Kanai, R

    2015-09-01

    The influential framework of 'predictive processing' suggests that prior probabilistic expectations influence, or even constitute, perceptual contents. This notion is evidenced by the facilitation of low-level perceptual processing by expectations. However, whether expectations can facilitate high-level components of perception remains unclear. We addressed this question by considering the influence of expectations on perceptual metacognition. To isolate the effects of expectation from those of attention we used a novel factorial design: expectation was manipulated by changing the probability that a Gabor target would be presented; attention was manipulated by instructing participants to perform or ignore a concurrent visual search task. We found that, independently of attention, metacognition improved when yes/no responses were congruent with expectations of target presence/absence. Results were modeled under a novel Bayesian signal detection theoretic framework which integrates bottom-up signal propagation with top-down influences, to provide a unified description of the mechanisms underlying perceptual decision and metacognition.

  7. Two-stage thermal/nonthermal waste treatment process

    SciTech Connect

    Rosocha, L.A.; Anderson, G.K.; Coogan, J.J.; Kang, M.; Tennant, R.A.; Wantuck, P.J.

    1993-05-01

    An innovative waste treatment technology is being developed in Los Alamos to address the destruction of hazardous organic wastes. The technology described in this report uses two stages: a packed bed reactor (PBR) in the first stage to volatilize and/or combust liquid organics and a silent discharge plasma (SDP) reactor to remove entrained hazardous compounds in the off-gas to even lower levels. We have constructed pre-pilot-scale PBR-SDP apparatus and tested the two stages separately and in combined modes. These tests are described in the report.

  8. Effects of emotional intensity under perceptual load: An event-related potentials (ERPs) study.

    PubMed

    Müller-Bardorff, Miriam; Schulz, Claudia; Peterburs, Jutta; Bruchmann, Maximilian; Mothes-Lasch, Martin; Miltner, Wolfgang; Straube, Thomas

    2016-05-01

    Effects of emotional intensity and valence on visual event-related potentials (ERPs) are still poorly understood, in particular in the context of limited attentional resources. In the present EEG study, we investigated the effect of emotional intensity of different emotional facial expressions on P1, N170, early posterior negativity (EPN) and late positive potential (LPP) while varying the amount of available attentional resources. A new stimulus set comprising 90 full color pictures of neutral, happy (low, high intensity), and angry (low, high intensity) expressions was developed. These facial expressions were presented centrally, superimposed by two horizontal bars, and participants engaged in a focal bars task. Availability of attentional resources was varied in two conditions by manipulating the difficulty of the focal bars task (low vs. high perceptual load). Our findings demonstrate intensity and valence effects of task-irrelevant facial expressions on early (N170) and intermediate processing stages (EPN). In addition, task-related effects of perceptual load evolved at intermediate processing stages and were full blown in the time window of LPP. In line with limited resource accounts, valence effects on N170 and EPN were reduced under high perceptual load. Interestingly, apart from this valence by load interaction no further interactions between stimulus and task-driven factors were obtained: Effects of emotional intensity were not modulated by the perceptual load of the focal bars task, indicating that emotional intensity was processed even though attentional resources were heavily restricted. PMID:26995785

  9. Effects of emotional intensity under perceptual load: An event-related potentials (ERPs) study.

    PubMed

    Müller-Bardorff, Miriam; Schulz, Claudia; Peterburs, Jutta; Bruchmann, Maximilian; Mothes-Lasch, Martin; Miltner, Wolfgang; Straube, Thomas

    2016-05-01

    Effects of emotional intensity and valence on visual event-related potentials (ERPs) are still poorly understood, in particular in the context of limited attentional resources. In the present EEG study, we investigated the effect of emotional intensity of different emotional facial expressions on P1, N170, early posterior negativity (EPN) and late positive potential (LPP) while varying the amount of available attentional resources. A new stimulus set comprising 90 full color pictures of neutral, happy (low, high intensity), and angry (low, high intensity) expressions was developed. These facial expressions were presented centrally, superimposed by two horizontal bars, and participants engaged in a focal bars task. Availability of attentional resources was varied in two conditions by manipulating the difficulty of the focal bars task (low vs. high perceptual load). Our findings demonstrate intensity and valence effects of task-irrelevant facial expressions on early (N170) and intermediate processing stages (EPN). In addition, task-related effects of perceptual load evolved at intermediate processing stages and were full blown in the time window of LPP. In line with limited resource accounts, valence effects on N170 and EPN were reduced under high perceptual load. Interestingly, apart from this valence by load interaction no further interactions between stimulus and task-driven factors were obtained: Effects of emotional intensity were not modulated by the perceptual load of the focal bars task, indicating that emotional intensity was processed even though attentional resources were heavily restricted.

  10. The Perceptual Cognitive Processes Underpinning Skilled Performance in Volleyball: Evidence From Eye-Movements and Verbal Reports of Thinking Involving an in Situ Representative Task

    PubMed Central

    Afonso, José; Garganta, Jêlio; Mcrobert, Allistair; Williams, Andrew M.; Mesquita, Isabel

    2012-01-01

    An extensive body of work has focused on the processes underpinning perceptual-cognitive expertise. The majority of researchers have used film-based simulations to capture superior performance. We combined eye movement recording and verbal reports of thinking to explore the processes underpinning skilled performance in a complex, dynamic, and externally paced representative volleyball task involving in situ data collection. Altogether, 27 female volleyball players performed as centre backcourt defenders in simulated sessions while wearing an eye-tracking device. After each sequence, athletes were questioned concerning their perception of the situation. The visual search strategies employed by the highly-skilled players were more exploratory than those used by skilled players, involving more fixations to a greater number of locations. Highly-skilled participants spent more time fixating on functional spaces between two or more display areas, while the skilled participants fixated on the ball trajectory and specific players. Moreover, highly-skilled players generated more condition concepts with higher levels of sophistication than their skilled counterparts. Findings highlight the value of using representative task designs to capture performance in situ. Key pointsDecision-making in complex sports relies deeply on perceptual-cognitive expertise. In turn, the effect of expertise is highly dependent on the nature and complexity of the task.Nonetheless, most researchers use simple tasks in their research designs, risking not capturing performance in a meaningful way. We proposed to use a live action setting with a complex task design, representative of real world situations.We combined eye movement registration with collection of immediate retrospective verbal reports. Although the two data sets are not directly comparable, they may be used in a complementary manner, providing a deeper and fuller understanding of the processes underpinning superior performance

  11. Perceptual Color Characterization of Cameras

    PubMed Central

    Vazquez-Corral, Javier; Connah, David; Bertalmío, Marcelo

    2014-01-01

    Color camera characterization, mapping outputs from the camera sensors to an independent color space, such as XY Z, is an important step in the camera processing pipeline. Until now, this procedure has been primarily solved by using a 3 × 3 matrix obtained via a least-squares optimization. In this paper, we propose to use the spherical sampling method, recently published by Finlayson et al., to perform a perceptual color characterization. In particular, we search for the 3 × 3 matrix that minimizes three different perceptual errors, one pixel based and two spatially based. For the pixel-based case, we minimize the CIE ΔE error, while for the spatial-based case, we minimize both the S-CIELAB error and the CID error measure. Our results demonstrate an improvement of approximately 3% for the ΔE error, 7% for the S-CIELAB error and 13% for the CID error measures. PMID:25490586

  12. Pseudo Perceptual Differentiation

    ERIC Educational Resources Information Center

    Silverman, Julian; King, Catherine

    1970-01-01

    Two studies employing rod-and-frame test (RFT) and a size-estimation measure of "extensiveness of scanning reported. Results indicated perceptual differentiation interpretation of RFT performance erroneous for certain kinds of Ss. (Author)

  13. Perceptually oriented hypnosis.

    PubMed

    Woodard, Fredrick J

    2003-04-01

    This theoretical article explores postulates representative of a perceptual frame of reference for a better understanding of hypnotic experiencing. This author contends that Perceptual Psychology, a theory first conceptualized by Snygg and Combs, as revised by Combs, Richards, and Richards in 1988, and Perceptually Oriented Hypnosis provide an effective way of understanding hypnosis, the therapist-client relationship, and has some implications as well for better comprehending psychopathology. Perceptually oriented hypnotic principles are shown to enhance the characeristics of the adequate personality, expand the phenomenal field, change personal meanings, and change aspects of the phenomenal self in the context of hypnosis. Implications for understanding differing views and conflicting perceptions of reality held by scientists and researchers are discussed. Implications for Dissociative Identity Disorder are also addressed. Research utilizing Giorgi's research methodology and Wasicsko's qualitative procedure for assessing educators' dispositions is suggested.

  14. Perceptual benefits of objecthood.

    PubMed

    Naber, Marnix; Carlson, Thomas A; Verstraten, Frans A J; Einhäuser, Wolfgang

    2011-01-01

    Object-based attention facilitates the processing of features that form the object. Two hypotheses are conceivable for how object-based attention is deployed to an object's features: first, the object is attended by selecting its features; alternatively, a configuration of features as such is attended by selecting the object representation they form. Only for the latter alternative, the perception of a feature configuration as entity ("objecthood") is a necessary condition for object-based attention. Disentangling the two alternatives requires the comparison of identical feature configurations that induce the perception of an object in one condition ("bound") and do not do so in another condition ("unbound"). We used an ambiguous stimulus, whose percept spontaneously switches between bound and unbound, while the stimulus itself remains unchanged. We tested discrimination on the boundary of the diamond as well as detection of probes inside and outside the diamond. We found discrimination performance to be increased if features were perceptually bound into an object. Furthermore, detection performance was higher within and lower outside the bound object as compared to the unbound configuration. Consequently, the facilitation of processing by object-based attention requires objecthood, that is, a unified internal representation of an "object"-not a mere collection of features.

  15. Terminal Stage Leukemia: Integrating Art Therapy and Family Process.

    ERIC Educational Resources Information Center

    Teufel, Emily Scudder

    1995-01-01

    Through art therapy, children express symbolically what they will not or cannot express emotionally to those close to them, and some children have the added stress of family problems that are magnified due to the situation. Presents the case history of a nine-year-old girl in the terminal stages of leukemia whose artwork symbolized family unity.…

  16. Developmental Stages in Receptive Grammar Acquisition: A Processability Theory Account

    ERIC Educational Resources Information Center

    Buyl, Aafke; Housen, Alex

    2015-01-01

    This study takes a new look at the topic of developmental stages in the second language (L2) acquisition of morphosyntax by analysing receptive learner data, a language mode that has hitherto received very little attention within this strand of research (for a recent and rare study, see Spinner, 2013). Looking at both the receptive and productive…

  17. The "Perceptual Wedge Hypothesis" as the basis for bilingual babies' phonetic processing advantage: new insights from fNIRS brain imaging.

    PubMed

    Petitto, L A; Berens, M S; Kovelman, I; Dubins, M H; Jasinska, K; Shalinsky, M

    2012-05-01

    In a neuroimaging study focusing on young bilinguals, we explored the brains of bilingual and monolingual babies across two age groups (younger 4-6 months, older 10-12 months), using fNIRS in a new event-related design, as babies processed linguistic phonetic (Native English, Non-Native Hindi) and non-linguistic Tone stimuli. We found that phonetic processing in bilingual and monolingual babies is accomplished with the same language-specific brain areas classically observed in adults, including the left superior temporal gyrus (associated with phonetic processing) and the left inferior frontal cortex (associated with the search and retrieval of information about meanings, and syntactic and phonological patterning), with intriguing developmental timing differences: left superior temporal gyrus activation was observed early and remained stably active over time, while left inferior frontal cortex showed greater increase in neural activation in older babies notably at the precise age when babies' enter the universal first-word milestone, thus revealing a first-time focal brain correlate that may mediate a universal behavioral milestone in early human language acquisition. A difference was observed in the older bilingual babies' resilient neural and behavioral sensitivity to Non-Native phonetic contrasts at a time when monolingual babies can no longer make such discriminations. We advance the "Perceptual Wedge Hypothesis" as one possible explanation for how exposure to greater than one language may alter neural and language processing in ways that we suggest are advantageous to language users. The brains of bilinguals and multilinguals may provide the most powerful window into the full neural "extent and variability" that our human species' language processing brain areas could potentially achieve.

  18. Transfer-Appropriate Processing in Recognition Memory: Perceptual and Conceptual Effects on Recognition Memory Depend on Task Demands

    ERIC Educational Resources Information Center

    Parks, Colleen M.

    2013-01-01

    Research examining the importance of surface-level information to familiarity in recognition memory tasks is mixed: Sometimes it affects recognition and sometimes it does not. One potential explanation of the inconsistent findings comes from the ideas of dual process theory of recognition and the transfer-appropriate processing framework, which…

  19. Relations between Perceptual and Conceptual Scope: How Global versus Local Processing Fits a Focus on Similarity versus Dissimilarity

    ERIC Educational Resources Information Center

    Forster, Jens

    2009-01-01

    Nine studies showed a bidirectional link (a) between a global processing style and generation of similarities and (b) between a local processing style and generation of dissimilarities. In Experiments 1-4, participants were primed with global versus local perception styles and then asked to work on an allegedly unrelated generation task. Across…

  20. Generalization of multisensory perceptual learning

    PubMed Central

    Powers III, Albert R.; Hillock-Dunn, Andrea; Wallace, Mark T.

    2016-01-01

    Life in a multisensory world requires the rapid and accurate integration of stimuli across the different senses. In this process, the temporal relationship between stimuli is critical in determining which stimuli share a common origin. Numerous studies have described a multisensory temporal binding window—the time window within which audiovisual stimuli are likely to be perceptually bound. In addition to characterizing this window’s size, recent work has shown it to be malleable, with the capacity for substantial narrowing following perceptual training. However, the generalization of these effects to other measures of perception is not known. This question was examined by characterizing the ability of training on a simultaneity judgment task to influence perception of the temporally-dependent sound-induced flash illusion (SIFI). Results do not demonstrate a change in performance on the SIFI itself following training. However, data do show an improved ability to discriminate rapidly-presented two-flash control conditions following training. Effects were specific to training and scaled with the degree of temporal window narrowing exhibited. Results do not support generalization of multisensory perceptual learning to other multisensory tasks. However, results do show that training results in improvements in visual temporal acuity, suggesting a generalization effect of multisensory training on unisensory abilities. PMID:27000988

  1. Variation transmission model for setting acceptance criteria in a multi-staged pharmaceutical manufacturing process.

    PubMed

    Montes, Richard O

    2012-03-01

    Pharmaceutical manufacturing processes consist of a series of stages (e.g., reaction, workup, isolation) to generate the active pharmaceutical ingredient (API). Outputs at intermediate stages (in-process control) and API need to be controlled within acceptance criteria to assure final drug product quality. In this paper, two methods based on tolerance interval to derive such acceptance criteria will be evaluated. The first method is serial worst case (SWC), an industry risk minimization strategy, wherein input materials and process parameters of a stage are fixed at their worst-case settings to calculate the maximum level expected from the stage. This maximum output then becomes input to the next stage wherein process parameters are again fixed at worst-case setting. The procedure is serially repeated throughout the process until the final stage. The calculated limits using SWC can be artificially high and may not reflect the actual process performance. The second method is the variation transmission (VT) using autoregressive model, wherein variation transmitted up to a stage is estimated by accounting for the recursive structure of the errors at each stage. Computer simulations at varying extent of variation transmission and process stage variability are performed. For the scenarios tested, VT method is demonstrated to better maintain the simulated confidence level and more precisely estimate the true proportion parameter than SWC. Real data examples are also presented that corroborate the findings from the simulation. Overall, VT is recommended for setting acceptance criteria in a multi-staged pharmaceutical manufacturing process.

  2. The Concept, "Perceptually Handicapped," Its Assets and Limitations.

    ERIC Educational Resources Information Center

    Blom, Gaston E.

    Perception is a process by which simple and complex information (stimuli) is experienced. We gain information about how such stimulus inputs are experienced by a child, for example, by his responses or outputs. Outputs are in the form of vocalizations and motor acts. Thus, the perceptual process is frequently called perceptual-motor. But the…

  3. Phonetic perceptual identification by native- and second-language speakers differentially activates brain regions involved with acoustic phonetic processing and those involved with articulatory-auditory/orosensory internal models.

    PubMed

    Callan, Daniel E; Jones, Jeffery A; Callan, Akiko M; Akahane-Yamada, Reiko

    2004-07-01

    This experiment investigates neural processes underlying perceptual identification of the same phonemes for native- and second-language speakers. A model is proposed implicating the use of articulatory-auditory and articulatory-orosensory mappings to facilitate perceptual identification under conditions in which the phonetic contrast is ambiguous, as in the case of second-language speakers. In contrast, native-language speakers are predicted to use auditory-based phonetic representations to a greater extent for perceptual identification than second-language speakers. The English /r-l/ phonetic contrast, although easy for native English speakers, is extremely difficult for native Japanese speakers who learned English as a second language after childhood. Twenty-two native English and twenty-two native Japanese speakers participated in this study. While undergoing event-related fMRI, subjects were aurally presented with syllables starting with a /r/, /l/, or a vowel and were required to rapidly identify the phoneme perceived by pushing one of three buttons with the left thumb. Consistent with the proposed model, the results show greater activity for second- over native-language speakers during perceptual identification of /r/ and /l/ relative to vowels in brain regions implicated with instantiating forward and inverse articulatory-auditory articulatory-orosensory models [Broca's area, anterior insula, anterior superior temporal sulcus/gyrus (STS/G), planum temporale (PT), superior temporal parietal area (Stp), SMG, and cerebellum]. The results further show that activity in brain regions implicated with instantiating these internal models is correlated with better /r/ and /l/ identification performance for second-language speakers. Greater activity found for native-language speakers especially in the anterior STG/S for /r/ and /l/ perceptual identification is consistent with the hypothesis that native-language speakers use auditory phonetic representations more

  4. Beta oscillations define discrete perceptual cycles in the somatosensory domain

    PubMed Central

    Baumgarten, Thomas J.; Schnitzler, Alfons; Lange, Joachim

    2015-01-01

    Whether seeing a movie, listening to a song, or feeling a breeze on the skin, we coherently experience these stimuli as continuous, seamless percepts. However, there are rare perceptual phenomena that argue against continuous perception but, instead, suggest discrete processing of sensory input. Empirical evidence supporting such a discrete mechanism, however, remains scarce and comes entirely from the visual domain. Here, we demonstrate compelling evidence for discrete perceptual sampling in the somatosensory domain. Using magnetoencephalography (MEG) and a tactile temporal discrimination task in humans, we find that oscillatory alpha- and low beta-band (8–20 Hz) cycles in primary somatosensory cortex represent neurophysiological correlates of discrete perceptual cycles. Our results agree with several theoretical concepts of discrete perceptual sampling and empirical evidence of perceptual cycles in the visual domain. Critically, these results show that discrete perceptual cycles are not domain-specific, and thus restricted to the visual domain, but extend to the somatosensory domain. PMID:26324922

  5. Perceptual learning in amnesia.

    PubMed

    Fahle, Manfred; Daum, Irene

    2002-01-01

    Evidence from experiments on perceptual learning, accumulated during the last few years, increasingly indicates that the relative 'front end' parts of the visual system are more plastic even in adults than was previously expected. Hence, it might be possible that perceptual learning is similar in several respects to procedural learning and may be achieved even without (declarative) memory traces present. Results on six patients suffering from global amnesia due to damage to hippocampal-diencephalic systems demonstrate, for the first time, that at least some amnesic patients are able to significantly improve performance in a visual hyperacuity task as a result of training, showing improvement as good as the observers in the control group. This result corroborates the notion of a relatively 'front end' location of at least some forms of perceptual learning.

  6. The Phenomenon of Task-Irrelevant Perceptual Learning

    PubMed Central

    Seitz, Aaron R; Watanabe, Takeo

    2009-01-01

    Task-irrelevant perceptual learning (TIPL) has captured a growing interest in the field of perceptual learning. The basic phenomenon is that stimulus features that are irrelevant to a subject’s task (i.e. convey no useful information to that task) can be learned due to their consistent presentation during task-performance. Here we review recent research on TIPL and focus on two key aspects of TIPL; 1) the mechanisms gating learning in TIPL, and, 2) what is learned through TIPL. We show that TIPL is gated by learning signals that are triggered from task processing or by rewards. These learning signals operate to enhance processing of individual stimulus features and appear to result in plasticity in early stages of visual processing. Furthermore, we discuss recent research that demonstrates that TIPL is not in opposition to theories of attention but instead that TIPL operates in concert with attention. Where attentional learning is best to enhance (or suppress) processing of stimuli of known task relevance, TIPL serves to enhance perception of stimuli that are originally inadequately processed by the brain. PMID:19665471

  7. Mathematical modeling of a single stage ultrasonically assisted distillation process.

    PubMed

    Mahdi, Taha; Ahmad, Arshad; Ripin, Adnan; Abdullah, Tuan Amran Tuan; Nasef, Mohamed M; Ali, Mohamad W

    2015-05-01

    The ability of sonication phenomena in facilitating separation of azeotropic mixtures presents a promising approach for the development of more intensified and efficient distillation systems than conventional ones. To expedite the much-needed development, a mathematical model of the system based on conservation principles, vapor-liquid equilibrium and sonochemistry was developed in this study. The model that was founded on a single stage vapor-liquid equilibrium system and enhanced with ultrasonic waves was coded using MATLAB simulator and validated with experimental data for ethanol-ethyl acetate mixture. The effects of both ultrasonic frequency and intensity on the relative volatility and azeotropic point were examined, and the optimal conditions were obtained using genetic algorithm. The experimental data validated the model with a reasonable accuracy. The results of this study revealed that the azeotropic point of the mixture can be totally eliminated with the right combination of sonication parameters and this can be utilized in facilitating design efforts towards establishing a workable ultrasonically intensified distillation system.

  8. Perceptual presence without counterfactual richness.

    PubMed

    Madary, Michael

    2014-01-01

    In this commentary, I suggest that non-visual perceptual modalities provide counterexamples to Seth's claim that perceptual presence depends on counterfactual richness. Then I suggest a modification to Seth's view that is not vulnerable to these counterexamples. PMID:24739124

  9. Impairment in Early Stages of Visual Information Processing in Nonpsychotic Schizotypic Individuals.

    ERIC Educational Resources Information Center

    Steronko, Robert J.; Woods, Donald J.

    1978-01-01

    This study investigated the perceptual functioning of individuals whose Minnesota Multiphasic Personality Inventory (MMPI-168) profiles indicated schizophrenic tendencies, but who did not exhibit marked thought disorder. (Author)

  10. ERP Evidence of Visualization at Early Stages of Visual Processing

    ERIC Educational Resources Information Center

    Page, Jonathan W.; Duhamel, Paul; Crognale, Michael A.

    2011-01-01

    Recent neuroimaging research suggests that early visual processing circuits are activated similarly during visualization and perception but have not demonstrated that the cortical activity is similar in character. We found functional equivalency in cortical activity by recording evoked potentials while color and luminance patterns were viewed and…

  11. Multisensory perceptual learning and sensory substitution.

    PubMed

    Proulx, Michael J; Brown, David J; Pasqualotto, Achille; Meijer, Peter

    2014-04-01

    One of the most exciting recent findings in neuroscience has been the capacity for neural plasticity in adult humans and animals. Studies of perceptual learning have provided key insights into the mechanisms of neural plasticity and the changes in functional neuroanatomy that it affords. Key questions in this field of research concern how practice of a task leads to specific or general improvement. Although much of this work has been carried out with a focus on a single sensory modality, primarily visual, there is increasing interest in multisensory perceptual learning. Here we will examine how advances in perceptual learning research both inform and can be informed by the development and advancement of sensory substitution devices for blind persons. To allow 'sight' to occur in the absence of visual input through the eyes, visual information can be transformed by a sensory substitution device into a representation that can be processed as sound or touch, and thus give one the potential to 'see' through the ears or tongue. Investigations of auditory, visual and multisensory perceptual learning can have key benefits for the advancement of sensory substitution, and the study of sensory deprivation and sensory substitution likewise will further the understanding of perceptual learning in general and the reverse hierarchy theory in particular. It also has significant importance for the developing understanding of the brain in metamodal terms, where functional brain areas might be best defined by the computations they carry out rather than by their sensory-specific processing role. PMID:23220697

  12. Multisensory perceptual learning and sensory substitution.

    PubMed

    Proulx, Michael J; Brown, David J; Pasqualotto, Achille; Meijer, Peter

    2014-04-01

    One of the most exciting recent findings in neuroscience has been the capacity for neural plasticity in adult humans and animals. Studies of perceptual learning have provided key insights into the mechanisms of neural plasticity and the changes in functional neuroanatomy that it affords. Key questions in this field of research concern how practice of a task leads to specific or general improvement. Although much of this work has been carried out with a focus on a single sensory modality, primarily visual, there is increasing interest in multisensory perceptual learning. Here we will examine how advances in perceptual learning research both inform and can be informed by the development and advancement of sensory substitution devices for blind persons. To allow 'sight' to occur in the absence of visual input through the eyes, visual information can be transformed by a sensory substitution device into a representation that can be processed as sound or touch, and thus give one the potential to 'see' through the ears or tongue. Investigations of auditory, visual and multisensory perceptual learning can have key benefits for the advancement of sensory substitution, and the study of sensory deprivation and sensory substitution likewise will further the understanding of perceptual learning in general and the reverse hierarchy theory in particular. It also has significant importance for the developing understanding of the brain in metamodal terms, where functional brain areas might be best defined by the computations they carry out rather than by their sensory-specific processing role.

  13. Frequent video game players resist perceptual interference.

    PubMed

    Berard, Aaron V; Cain, Matthew S; Watanabe, Takeo; Sasaki, Yuka

    2015-01-01

    Playing certain types of video games for a long time can improve a wide range of mental processes, from visual acuity to cognitive control. Frequent gamers have also displayed generalized improvements in perceptual learning. In the Texture Discrimination Task (TDT), a widely used perceptual learning paradigm, participants report the orientation of a target embedded in a field of lines and demonstrate robust over-night improvement. However, changing the orientation of the background lines midway through TDT training interferes with overnight improvements in overall performance on TDT. Interestingly, prior research has suggested that this effect will not occur if a one-hour break is allowed in between the changes. These results have suggested that after training is over, it may take some time for learning to become stabilized and resilient against interference. Here, we tested whether frequent gamers have faster stabilization of perceptual learning compared to non-gamers and examined the effect of daily video game playing on interference of training of TDT with one background orientation on perceptual learning of TDT with a different background orientation. As a result, we found that non-gamers showed overnight performance improvement only on one background orientation, replicating previous results with the interference in TDT. In contrast, frequent gamers demonstrated overnight improvements in performance with both background orientations, suggesting that they are better able to overcome interference in perceptual learning. This resistance to interference suggests that video game playing not only enhances the amplitude and speed of perceptual learning but also leads to faster and/or more robust stabilization of perceptual learning.

  14. Low-level sensory plasticity during task-irrelevant perceptual learning: evidence from conventional and double training procedures.

    PubMed

    Pilly, Praveen K; Grossberg, Stephen; Seitz, Aaron R

    2010-02-22

    Studies of perceptual learning have focused on aspects of learning that are related to early stages of sensory processing. However, conclusions that perceptual learning results in low-level sensory plasticity are controversial, since such learning may also be attributed to plasticity in later stages of sensory processing or in readout from sensory to decision stages, or to changes in high-level central processing. To address this controversy, we developed a novel random dot motion (RDM) stimulus to target motion cells selective to contrast polarity by ensuring the motion direction information arises only from signal dot onsets and not their offsets, and used these stimuli in the paradigm of task-irrelevant perceptual learning (TIPL). In TIPL, learning is achieved in response to a stimulus by subliminally pairing that stimulus with the targets of an unrelated training task. In this manner, we are able to probe learning for an aspect of motion processing thought to be a function of directional V1 simple cells with a learning procedure that dissociates the learned stimulus from the decision processes relevant to the training task. Our results show direction-selective learning for the designated contrast polarity that does not transfer to the opposite contrast polarity. This polarity specificity was replicated in a double training procedure in which subjects were additionally exposed to the opposite polarity. Taken together, these results suggest that TIPL for motion stimuli may occur at the stage of directional V1 simple cells. Finally, a theoretical explanation is provided to understand the data.

  15. Acetylcholine and Olfactory Perceptual Learning

    ERIC Educational Resources Information Center

    Wilson, Donald A.; Fletcher, Max L.; Sullivan, Regina M.

    2004-01-01

    Olfactory perceptual learning is a relatively long-term, learned increase in perceptual acuity, and has been described in both humans and animals. Data from recent electrophysiological studies have indicated that olfactory perceptual learning may be correlated with changes in odorant receptive fields of neurons in the olfactory bulb and piriform…

  16. Perceptual-Motor Dysfunction.

    ERIC Educational Resources Information Center

    Pyfer, Jean L.

    Discussed are theoretical and treatment aspects of perceptual motor dysfunction and rehabilitation in 4- to 12-year-old academically failing children involved in a 3-year investigation at the University of Kansas. The program is said to stress increasing the amount of stimulation received by sensory receptors of the vestibular, reflex, and haptic…

  17. Perceptual Learning in Speech

    ERIC Educational Resources Information Center

    Norris, Dennis; McQueen, James M.; Cutler, Anne

    2003-01-01

    This study demonstrates that listeners use lexical knowledge in perceptual learning of speech sounds. Dutch listeners first made lexical decisions on Dutch words and nonwords. The final fricative of 20 critical words had been replaced by an ambiguous sound, between [f] and [s]. One group of listeners heard ambiguous [f]-final words (e.g.,…

  18. Late-stage orogenic processes: How to link surface motion with distinct lithospheric processes

    NASA Astrophysics Data System (ADS)

    Neubauer, F.; Heberer, B.

    2009-04-01

    There is still a lack of knowledge of surface expression caused by deep-seated lithospheric processes, and how such processes could be distinguished from other, e.g. climate-induced, surface processes like denudation. Surface expressions of deep-seated lithospheric processes in convergent settings are expected to have been long-lived and to show large wave-length structures creating a dynamic topography (Wortel and Spakman, 2000; Cloetingh and Ziegler, 2007). Resulting continent-continent collisional orogens are bivergent, and the principal vergency of collisional orogens is controlled by the previous subduction of oceanic lithosphere (Beaumont et al., 1996). A number of tectonic processes are shown to be active during late orogenic phases and these processes particularly result in specific patterns of surface uplift and denudation of the evolving orogens as well as subsidence in the associated foreland basin. A number of these processes are not fully understood. Late-stage orogenic processes include, among others, slab break-off, slab delamination respectively of lithospheric roots, back-thrusting, tectonic indentation and consequent orogen-parallel lateral extrusion and formation of Subduction-Transform Edge Propagator (STEP) faults acting on the subducting lithosphere (Molnar and Tapponnier, 1975; Wortel and Spakman, 2000; Ratschbacher et al., 1991; Govers and Wortel, 2005). Here, we discuss these processes mainly in terms of their near-surface geological expressions within the orogen and the associated foreland basins, and how these processes could be distinguished by such geological features. We also show distinct theoretical models applied to the arcuate Alpine-Balkan-Carpathian-Dinaric system, which is driven by the oblique convergence of Africa-Europe. Slab-break-off results in lateral orogen-parallel migration of sharp subsidence in a linear belt in front of the slab window, coupled subsidence and subsequent uplift/basin inversion of peripheral foreland

  19. Selective Attention to Perceptual Dimensions and Switching between Dimensions

    ERIC Educational Resources Information Center

    Meiran, Nachshon; Dimov, Eduard; Ganel, Tzvi

    2013-01-01

    In the present experiments, the question being addressed was whether switching attention between perceptual dimensions and selective attention to dimensions are processes that compete over a common resource? Attention to perceptual dimensions is usually studied by requiring participants to ignore a never-relevant dimension. Selection failure…

  20. Bacterial diversity at different stages of the composting process

    PubMed Central

    2010-01-01

    Background Composting is an aerobic microbiological process that is facilitated by bacteria and fungi. Composting is also a method to produce fertilizer or soil conditioner. Tightened EU legislation now requires treatment of the continuously growing quantities of organic municipal waste before final disposal. However, some full-scale composting plants experience difficulties with the efficiency of biowaste degradation and with the emission of noxious odours. In this study we examine the bacterial species richness and community structure of an optimally working pilot-scale compost plant, as well as a full-scale composting plant experiencing typical problems. Bacterial species composition was determined by isolating total DNA followed by amplifying and sequencing the gene encoding the 16S ribosomal RNA. Results Over 1500 almost full-length 16S rRNA gene sequences were analysed and of these, over 500 were present only as singletons. Most of the sequences observed in either one or both of the composting processes studied here were similar to the bacterial species reported earlier in composts, including bacteria from the phyla Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria and Deinococcus-Thermus. In addition, a number of previously undetected bacterial phylotypes were observed. Statistical calculations estimated a total bacterial diversity of over 2000 different phylotypes in the studied composts. Conclusions Interestingly, locally enriched or evolved bacterial variants of familiar compost species were observed in both composts. A detailed comparison of the bacterial diversity revealed a large difference in composts at the species and strain level from the different composting plants. However, at the genus level, the difference was much smaller and illustrated a delay of the composting process in the full-scale, sub-optimally performing plants. PMID:20350306

  1. Metamodeling and Optimization of a Blister Copper Two-Stage Production Process

    NASA Astrophysics Data System (ADS)

    Jarosz, Piotr; Kusiak, Jan; Małecki, Stanisław; Morkisz, Paweł; Oprocha, Piotr; Pietrucha, Wojciech; Sztangret, Łukasz

    2016-06-01

    It is often difficult to estimate parameters for a two-stage production process of blister copper (containing 99.4 wt.% of Cu metal) as well as those for most industrial processes with high accuracy, which leads to problems related to process modeling and control. The first objective of this study was to model flash smelting and converting of Cu matte stages using three different techniques: artificial neural networks, support vector machines, and random forests, which utilized noisy technological data. Subsequently, more advanced models were applied to optimize the entire process (which was the second goal of this research). The obtained optimal solution was a Pareto-optimal one because the process consisted of two stages, making the optimization problem a multi-criteria one. A sequential optimization strategy was employed, which aimed for optimal control parameters consecutively for both stages. The obtained optimal output parameters for the first smelting stage were used as input parameters for the second converting stage. Finally, a search for another optimal set of control parameters for the second stage of a Kennecott-Outokumpu process was performed. The optimization process was modeled using a Monte-Carlo method, and both modeling parameters and computed optimal solutions are discussed.

  2. Adaptation and perceptual norms in color vision.

    PubMed

    Webster, Michael A; Leonard, Deanne

    2008-11-01

    Many perceptual dimensions are thought to be represented relative to an average value or norm. Models of norm-based coding assume that the norm appears psychologically neutral because it reflects a neutral response in the underlying neural code. We tested this assumption in human color vision by asking how judgments of "white" are affected as neural responses are altered by adaptation. The adapting color was varied to determine the stimulus level that did not bias the observer's subjective white point. This level represents a response norm at the stages at which sensitivity is regulated by the adaptation, and we show that these response norms correspond to the perceptually neutral stimulus and that they can account for how the perception of white varies both across different observers and within the same observer at different locations in the visual field. We also show that individual differences in perceived white are reduced when observers are exposed to a common white adapting stimulus, suggesting that the perceptual differences are due in part to differences in how neural responses are normalized. These results suggest a close link between the norms for appearance and coding in color vision and illustrate a general paradigm for exploring this link in other perceptual domains.

  3. Perceptual learning and human expertise

    NASA Astrophysics Data System (ADS)

    Kellman, Philip J.; Garrigan, Patrick

    2009-06-01

    We consider perceptual learning: experience-induced changes in the way perceivers extract information. Often neglected in scientific accounts of learning and in instruction, perceptual learning is a fundamental contributor to human expertise and is crucial in domains where humans show remarkable levels of attainment, such as language, chess, music, and mathematics. In Section 2, we give a brief history and discuss the relation of perceptual learning to other forms of learning. We consider in Section 3 several specific phenomena, illustrating the scope and characteristics of perceptual learning, including both discovery and fluency effects. We describe abstract perceptual learning, in which structural relationships are discovered and recognized in novel instances that do not share constituent elements or basic features. In Section 4, we consider primary concepts that have been used to explain and model perceptual learning, including receptive field change, selection, and relational recoding. In Section 5, we consider the scope of perceptual learning, contrasting recent research, focused on simple sensory discriminations, with earlier work that emphasized extraction of invariance from varied instances in more complex tasks. Contrary to some recent views, we argue that perceptual learning should not be confined to changes in early sensory analyzers. Phenomena at various levels, we suggest, can be unified by models that emphasize discovery and selection of relevant information. In a final section, we consider the potential role of perceptual learning in educational settings. Most instruction emphasizes facts and procedures that can be verbalized, whereas expertise depends heavily on implicit pattern recognition and selective extraction skills acquired through perceptual learning. We consider reasons why perceptual learning has not been systematically addressed in traditional instruction, and we describe recent successful efforts to create a technology of perceptual

  4. Perceptual learning and human expertise.

    PubMed

    Kellman, Philip J; Garrigan, Patrick

    2009-06-01

    We consider perceptual learning: experience-induced changes in the way perceivers extract information. Often neglected in scientific accounts of learning and in instruction, perceptual learning is a fundamental contributor to human expertise and is crucial in domains where humans show remarkable levels of attainment, such as language, chess, music, and mathematics. In Section 2, we give a brief history and discuss the relation of perceptual learning to other forms of learning. We consider in Section 3 several specific phenomena, illustrating the scope and characteristics of perceptual learning, including both discovery and fluency effects. We describe abstract perceptual learning, in which structural relationships are discovered and recognized in novel instances that do not share constituent elements or basic features. In Section 4, we consider primary concepts that have been used to explain and model perceptual learning, including receptive field change, selection, and relational recoding. In Section 5, we consider the scope of perceptual learning, contrasting recent research, focused on simple sensory discriminations, with earlier work that emphasized extraction of invariance from varied instances in more complex tasks. Contrary to some recent views, we argue that perceptual learning should not be confined to changes in early sensory analyzers. Phenomena at various levels, we suggest, can be unified by models that emphasize discovery and selection of relevant information. In a final section, we consider the potential role of perceptual learning in educational settings. Most instruction emphasizes facts and procedures that can be verbalized, whereas expertise depends heavily on implicit pattern recognition and selective extraction skills acquired through perceptual learning. We consider reasons why perceptual learning has not been systematically addressed in traditional instruction, and we describe recent successful efforts to create a technology of perceptual

  5. The Development of Perceptual Grouping Biases in Infancy: A Japanese-English Cross-Linguistic Study

    ERIC Educational Resources Information Center

    Yoshida, Katherine A.; Iversen, John R.; Patel, Aniruddh D.; Mazuka, Reiko; Nito, Hiromi; Gervain, Judit; Werker, Janet F.

    2010-01-01

    Perceptual grouping has traditionally been thought to be governed by innate, universal principles. However, recent work has found differences in Japanese and English speakers' non-linguistic perceptual grouping, implicating language in non-linguistic perceptual processes (Iversen, Patel, & Ohgushi, 2008). Two experiments test Japanese- and…

  6. Generalization of Perceptual Learning of Vocoded Speech

    ERIC Educational Resources Information Center

    Hervais-Adelman, Alexis G.; Davis, Matthew H.; Johnsrude, Ingrid S.; Taylor, Karen J.; Carlyon, Robert P.

    2011-01-01

    Recent work demonstrates that learning to understand noise-vocoded (NV) speech alters sublexical perceptual processes but is enhanced by the simultaneous provision of higher-level, phonological, but not lexical content (Hervais-Adelman, Davis, Johnsrude, & Carlyon, 2008), consistent with top-down learning (Davis, Johnsrude, Hervais-Adelman,…

  7. The Mirage of the Perceptually Handicapped Syndrome

    ERIC Educational Resources Information Center

    West, Malcolm

    1970-01-01

    Emphasize the importance of a positive diagnosis of perceptual handicap, rather than a wastebasket" diagnosis. The tendency to separate the child's handicap from his feelings about it is reflected in the treatment process. There exists little concern with the totality of the child's development in his total environment. (Author)

  8. Varieties of perceptual learning.

    PubMed

    Mackintosh, N J

    2009-05-01

    Although most studies of perceptual learning in human participants have concentrated on the changes in perception assumed to be occurring, studies of nonhuman animals necessarily measure discrimination learning and generalization and remain agnostic on the question of whether changes in behavior reflect changes in perception. On the other hand, animal studies do make it easier to draw a distinction between supervised and unsupervised learning. Differential reinforcement will surely teach animals to attend to some features of a stimulus array rather than to others. But it is an open question as to whether such changes in attention underlie the enhanced discrimination seen after unreinforced exposure to such an array. I argue that most instances of unsupervised perceptual learning observed in animals (and at least some in human animals) are better explained by appeal to well-established principles and phenomena of associative learning theory: excitatory and inhibitory associations between stimulus elements, latent inhibition, and habituation.

  9. Development of a replacement for trichloroethylene in the two-stage cleaning process

    SciTech Connect

    Harding, W.B.

    1992-12-01

    A solvent was sought to replace trichloroethylene in the two-stage cleaning process that is used in the Allied-Signal Inc., Kansas City Division (KCD) Miniature Electro-Mechanical Assembly Department. The process is an ultrasonic cleaning process in which product is first cleaned in trichloroethylene and then in isopropyl alcohol. After a general review of the properties of available solvents, isopropyl alcohol, d-limonene, and a synthetic mineral spirits, were chosen to be evaluated as trichloroethylene replacements. Stainless steel test panels were cleaned and then soiled with several different organic materials. Certain of the panels were cleaned by the two-stage process. The others were cleaned by the two-stage process using one or another of the solvents under evaluation in the place of the trichloroethylene. The cleanliness of the panels was determined by Auger and photoelectron spectroscopy. The panels cleaned with any of the three solvents under evaluation were found to be as clean as those cleaned by the standard two-stage process. Because of simplicity and minimization of inventory, it is recommended that the two-stage process be changed to use isopropyl alcohol in both stages.

  10. Three stages of emotional word processing: an ERP study with rapid serial visual presentation.

    PubMed

    Zhang, Dandan; He, Weiqi; Wang, Ting; Luo, Wenbo; Zhu, Xiangru; Gu, Ruolei; Li, Hong; Luo, Yue-Jia

    2014-12-01

    Rapid responses to emotional words play a crucial role in social communication. This study employed event-related potentials to examine the time course of neural dynamics involved in emotional word processing. Participants performed a dual-target task in which positive, negative and neutral adjectives were rapidly presented. The early occipital P1 was found larger when elicited by negative words, indicating that the first stage of emotional word processing mainly differentiates between non-threatening and potentially threatening information. The N170 and the early posterior negativity were larger for positive and negative words, reflecting the emotional/non-emotional discrimination stage of word processing. The late positive component not only distinguished emotional words from neutral words, but also differentiated between positive and negative words. This represents the third stage of emotional word processing, the emotion separation. Present results indicated that, similar with the three-stage model of facial expression processing; the neural processing of emotional words can also be divided into three stages. These findings prompt us to believe that the nature of emotion can be analyzed by the brain independent of stimulus type, and that the three-stage scheme may be a common model for emotional information processing in the context of limited attentional resources.

  11. Early-stage visual processing abnormalities in high-functioning autism spectrum disorder (ASD).

    PubMed

    Baruth, Joshua M; Casanova, Manuel F; Sears, Lonnie; Sokhadze, Estate

    2010-06-01

    It has been reported that individuals with autism spectrum disorder (ASD) have abnormal responses to the sensory environment. For these individuals sensory overload can impair functioning, raise physiological stress, and adversely affect social interaction. Early-stage (i.e. within 200ms of stimulus onset) auditory processing abnormalities have been widely examined in ASD using event-related potentials (ERP), while ERP studies investigating early-stage visual processing in ASD are less frequent. We wanted to test the hypothesis of early-stage visual processing abnormalities in ASD by investigating ERPs elicited in a visual oddball task using illusory figures. Our results indicate that individuals with ASD have abnormally large cortical responses to task irrelevant stimuli over both parieto-occipital and frontal regions-of-interest (ROI) during early stages of visual processing compared to the control group. Furthermore, ASD patients showed signs of an overall disruption in stimulus discrimination, and had a significantly higher rate of motor response errors.

  12. Perceptually controlled doping for audio source separation

    NASA Astrophysics Data System (ADS)

    Mahé, Gaël; Nadalin, Everton Z.; Suyama, Ricardo; Romano, João MT

    2014-12-01

    The separation of an underdetermined audio mixture can be performed through sparse component analysis (SCA) that relies however on the strong hypothesis that source signals are sparse in some domain. To overcome this difficulty in the case where the original sources are available before the mixing process, the informed source separation (ISS) embeds in the mixture a watermark, which information can help a further separation. Though powerful, this technique is generally specific to a particular mixing setup and may be compromised by an additional bitrate compression stage. Thus, instead of watermarking, we propose a `doping' method that makes the time-frequency representation of each source more sparse, while preserving its audio quality. This method is based on an iterative decrease of the distance between the distribution of the signal and a target sparse distribution, under a perceptual constraint. We aim to show that the proposed approach is robust to audio coding and that the use of the sparsified signals improves the source separation, in comparison with the original sources. In this work, the analysis is made only in instantaneous mixtures and focused on voice sources.

  13. Integrative functional genomic analysis unveils the differing dysregulated metabolic processes across hepatocellular carcinoma stages.

    PubMed

    Ramesh, Vignesh; Ganesan, Kumaresan

    2016-08-15

    Hepatocellular carcinoma (HCC) is a highly heterogeneous disease and the development of targeted therapeutics is still at an early stage. The 'omics' based genome-wide profiling comprising the transcriptome, miRNome and proteome are highly useful in identifying the deregulated molecular processes involved in hepatocarcinogenesis. One of the end products and processes of the central dogma being the metabolites and metabolic processes mediate the cellular functions. In recent years, metabolomics based investigations have revealed the major deregulated metabolic processes involved in carcinogenesis. However, the integrative analysis of the holistic metabolic processes with genomics is at an early stage. Since the gene-sets are highly useful in assessing the biological processes and pathways, we made an attempt to infer the deregulated cellular metabolic processes involved in HCC by employing metabolism associated gene-set enrichment analysis. Further, the metabolic process enrichment scores were integrated with the transcriptome profiles of HCC. Integrative analysis shows three distinct metabolic deregulations: i) hepatocyte function related molecular processes involving lipid/fatty acid/bile acid synthesis, ii) inflammatory processes with cytokine, sphingolipid & chondriotin sulphate metabolism and iii) enriched nucleotide metabolic process involving purine/pyrimidine & glucose mediated catabolic process, in hepatocarcinogenesis. The three distinct metabolic processes were found to occur both in tumor and liver cancer cell line profiles. Unsupervised hierarchical clustering of the metabolic processes along with clinical sample information has identified two major clusters based on AFP (alpha-fetoprotein) and metastasis. The study reveals the three major regulatory processes involved in HCC stages. PMID:27107678

  14. Integrative functional genomic analysis unveils the differing dysregulated metabolic processes across hepatocellular carcinoma stages.

    PubMed

    Ramesh, Vignesh; Ganesan, Kumaresan

    2016-08-15

    Hepatocellular carcinoma (HCC) is a highly heterogeneous disease and the development of targeted therapeutics is still at an early stage. The 'omics' based genome-wide profiling comprising the transcriptome, miRNome and proteome are highly useful in identifying the deregulated molecular processes involved in hepatocarcinogenesis. One of the end products and processes of the central dogma being the metabolites and metabolic processes mediate the cellular functions. In recent years, metabolomics based investigations have revealed the major deregulated metabolic processes involved in carcinogenesis. However, the integrative analysis of the holistic metabolic processes with genomics is at an early stage. Since the gene-sets are highly useful in assessing the biological processes and pathways, we made an attempt to infer the deregulated cellular metabolic processes involved in HCC by employing metabolism associated gene-set enrichment analysis. Further, the metabolic process enrichment scores were integrated with the transcriptome profiles of HCC. Integrative analysis shows three distinct metabolic deregulations: i) hepatocyte function related molecular processes involving lipid/fatty acid/bile acid synthesis, ii) inflammatory processes with cytokine, sphingolipid & chondriotin sulphate metabolism and iii) enriched nucleotide metabolic process involving purine/pyrimidine & glucose mediated catabolic process, in hepatocarcinogenesis. The three distinct metabolic processes were found to occur both in tumor and liver cancer cell line profiles. Unsupervised hierarchical clustering of the metabolic processes along with clinical sample information has identified two major clusters based on AFP (alpha-fetoprotein) and metastasis. The study reveals the three major regulatory processes involved in HCC stages.

  15. Empirical study of classification process for two-stage turbo air classifier in series

    NASA Astrophysics Data System (ADS)

    Yu, Yuan; Liu, Jiaxiang; Li, Gang

    2013-05-01

    The suitable process parameters for a two-stage turbo air classifier are important for obtaining the ultrafine powder that has a narrow particle-size distribution, however little has been published internationally on the classification process for the two-stage turbo air classifier in series. The influence of the process parameters of a two-stage turbo air classifier in series on classification performance is empirically studied by using aluminum oxide powders as the experimental material. The experimental results show the following: 1) When the rotor cage rotary speed of the first-stage classifier is increased from 2 300 r/min to 2 500 r/min with a constant rotor cage rotary speed of the second-stage classifier, classification precision is increased from 0.64 to 0.67. However, in this case, the final ultrafine powder yield is decreased from 79% to 74%, which means the classification precision and the final ultrafine powder yield can be regulated through adjusting the rotor cage rotary speed of the first-stage classifier. 2) When the rotor cage rotary speed of the second-stage classifier is increased from 2 500 r/min to 3 100 r/min with a constant rotor cage rotary speed of the first-stage classifier, the cut size is decreased from 13.16 μm to 8.76 μm, which means the cut size of the ultrafine powder can be regulated through adjusting the rotor cage rotary speed of the second-stage classifier. 3) When the feeding speed is increased from 35 kg/h to 50 kg/h, the "fish-hook" effect is strengthened, which makes the ultrafine powder yield decrease. 4) To weaken the "fish-hook" effect, the equalization of the two-stage wind speeds or the combination of a high first-stage wind speed with a low second-stage wind speed should be selected. This empirical study provides a criterion of process parameter configurations for a two-stage or multi-stage classifier in series, which offers a theoretical basis for practical production.

  16. Liquid phase methanol reactor staging process for the production of methanol

    DOEpatents

    Bonnell, Leo W.; Perka, Alan T.; Roberts, George W.

    1988-01-01

    The present invention is a process for the production of methanol from a syngas feed containing carbon monoxide, carbon dioxide and hydrogen. Basically, the process is the combination of two liquid phase methanol reactors into a staging process, such that each reactor is operated to favor a particular reaction mechanism. In the first reactor, the operation is controlled to favor the hydrogenation of carbon monoxide, and in the second reactor, the operation is controlled so as to favor the hydrogenation of carbon dioxide. This staging process results in substantial increases in methanol yield.

  17. Neural Dynamics of Emotional Salience Processing in Response to Voices during the Stages of Sleep

    PubMed Central

    Chen, Chenyi; Sung, Jia-Ying; Cheng, Yawei

    2016-01-01

    Sleep has been related to emotional functioning. However, the extent to which emotional salience is processed during sleep is unknown. To address this concern, we investigated night sleep in healthy adults regarding brain reactivity to the emotionally (happily, fearfully) spoken meaningless syllables dada, along with correspondingly synthesized nonvocal sounds. Electroencephalogram (EEG) signals were continuously acquired during an entire night of sleep while we applied a passive auditory oddball paradigm. During all stages of sleep, mismatch negativity (MMN) in response to emotional syllables, which is an index for emotional salience processing of voices, was detected. In contrast, MMN to acoustically matching nonvocal sounds was undetected during Sleep Stage 2 and 3 as well as rapid eye movement (REM) sleep. Post-MMN positivity (PMP) was identified with larger amplitudes during Stage 3, and at earlier latencies during REM sleep, relative to wakefulness. These findings clearly demonstrated the neural dynamics of emotional salience processing during the stages of sleep. PMID:27378870

  18. Neural Dynamics of Emotional Salience Processing in Response to Voices during the Stages of Sleep.

    PubMed

    Chen, Chenyi; Sung, Jia-Ying; Cheng, Yawei

    2016-01-01

    Sleep has been related to emotional functioning. However, the extent to which emotional salience is processed during sleep is unknown. To address this concern, we investigated night sleep in healthy adults regarding brain reactivity to the emotionally (happily, fearfully) spoken meaningless syllables dada, along with correspondingly synthesized nonvocal sounds. Electroencephalogram (EEG) signals were continuously acquired during an entire night of sleep while we applied a passive auditory oddball paradigm. During all stages of sleep, mismatch negativity (MMN) in response to emotional syllables, which is an index for emotional salience processing of voices, was detected. In contrast, MMN to acoustically matching nonvocal sounds was undetected during Sleep Stage 2 and 3 as well as rapid eye movement (REM) sleep. Post-MMN positivity (PMP) was identified with larger amplitudes during Stage 3, and at earlier latencies during REM sleep, relative to wakefulness. These findings clearly demonstrated the neural dynamics of emotional salience processing during the stages of sleep. PMID:27378870

  19. Explaining seeing? Disentangling qualia from perceptual organization.

    PubMed

    Ibáñez, Agustin; Bekinschtein, Tristan

    2010-09-01

    Abstract Visual perception and integration seem to play an essential role in our conscious phenomenology. Relatively local neural processing of reentrant nature may explain several visual integration processes (feature binding or figure-ground segregation, object recognition, inference, competition), even without attention or cognitive control. Based on the above statements, should the neural signatures of visual integration (via reentrant process) be non-reportable phenomenological qualia? We argue that qualia are not required to understand this perceptual organization.

  20. Catalytic two-stage coal liquefaction process having improved nitrogen removal

    DOEpatents

    Comolli, Alfred G.

    1991-01-01

    A process for catalytic multi-stage hydrogenation and liquefaction of coal to produce high yields of low-boiling hydrocarbon liquids containing low concentrations of nitogen compounds. First stage catalytic reaction conditions are 700.degree.-800.degree. F. temperature, 1500-3500 psig hydrogen partial pressure, with the space velocity maintained in a critical range of 10-40 lb coal/hr ft.sup.3 catalyst settled volume. The first stage catalyst has 0.3-1.2 cc/gm total pore volume with at least 25% of the pore volume in pores having diameters of 200-2000 Angstroms. Second stage reaction conditions are 760.degree.-870.degree. F. temperature with space velocity exceeding that in the first stage reactor, so as to achieve increased hydrogenation yield of low-boiling hydrocarbon liquid products having at least 75% removal of nitrogen compounds from the coal-derived liquid products.

  1. Novel two stage bio-oxidation and chlorination process for high strength hazardous coal carbonization effluent.

    PubMed

    Manekar, Pravin; Biswas, Rima; Karthik, Manikavasagam; Nandy, Tapas

    2011-05-15

    Effluent generated from coal carbonization to coke was characterized with high organic content, phenols, ammonium nitrogen, and cyanides. A full scale effluent treatment plant (ETP) working on the principle of single stage carbon-nitrogen bio-oxidation process (SSCNBP) revealed competition between heterotrophic and autotrophic bacteria in the bio-degradation and nitrification process. The effluent was pretreated in a stripper and further combined with other streams to treat in the SSCNBP. Laboratory studies were carried on process and stripped effluents in a bench scale model of ammonia stripper and a two stage bio-oxidation process. The free ammonia removal efficiency of stripper was in the range 70-89%. Bench scale studies of the two stage bio-oxidation process achieved a carbon-nitrogen reduction at 6 days hydraulic retention time (HRT) operating in an extended aeration mode. This paper addresses the studies on selection of a treatment process for removal of organic matter, phenols, cyanide and ammonia nitrogen. The treatment scheme comprising ammonia stripping (pretreatment) followed by the two stage bio-oxidation and chlorination process met the Indian Standards for discharge into Inland Surface Waters. This treatment process package offers a techno-economically viable treatment scheme to neuter hazardous effluent generated from coal carbonization process. PMID:21371822

  2. The Discovery of Processing Stages: Extension of Sternberg’s Method

    PubMed Central

    Anderson, John R.; Zhang, Qiong; Borst, Jelmer P.; Walsh, Matthew M.

    2016-01-01

    We introduce a method for measuring the number and durations of processing stages from the electroencephalographic (EEG) signal and apply it to the study of associative recognition. Using an extension of past research that combines multivariate pattern analysis (MVPA) with hidden semi-Markov models (HSMMs), the approach identifies on a trial-by-trial basis where brief sinusoidal peaks (called bumps) are added to the ongoing EEG signal. We propose that these bumps mark the onset of critical cognitive stages in processing. The results of the analysis can be used to guide the development of detailed process models. Applied to the associative recognition task, the HSMM-MVPA method indicates that the effects of associative strength and probe type are localized to a memory retrieval stage and a decision stage. This is in line with a previously developed ACT-R process model of the task. As a test of the generalization of our method we also apply it to a data set on the Sternberg working memory task collected by Jacobs et al. (2006). The analysis generalizes robustly, and localizes the typical set size effect in a late comparison/decision stage. In addition to providing information about the number and durations of stages in associative recognition, our analysis sheds light on the ERP components implicated in the study of recognition memory. PMID:27135600

  3. Associative fear learning and perceptual discrimination: a perceptual pathway in the development of chronic pain.

    PubMed

    Zaman, Jonas; Vlaeyen, Johan W S; Van Oudenhove, Lukas; Wiech, Katja; Van Diest, Ilse

    2015-04-01

    Recent neuropsychological theories emphasize the influence of maladaptive learning and memory processes on pain perception. However, the precise relationship between these processes as well as the underlying mechanisms remain poorly understood; especially the role of perceptual discrimination and its modulation by associative fear learning has received little attention so far. Experimental work with exteroceptive stimuli consistently points to effects of fear learning on perceptual discrimination acuity. In addition, clinical observations have revealed that in individuals with chronic pain perceptual discrimination is impaired, and that tactile discrimination training reduces pain. Based on these findings, we present a theoretical model of which the central tenet is that associative fear learning contributes to the development of chronic pain through impaired interoceptive and proprioceptive discrimination acuity.

  4. Associative fear learning and perceptual discrimination: a perceptual pathway in the development of chronic pain.

    PubMed

    Zaman, Jonas; Vlaeyen, Johan W S; Van Oudenhove, Lukas; Wiech, Katja; Van Diest, Ilse

    2015-04-01

    Recent neuropsychological theories emphasize the influence of maladaptive learning and memory processes on pain perception. However, the precise relationship between these processes as well as the underlying mechanisms remain poorly understood; especially the role of perceptual discrimination and its modulation by associative fear learning has received little attention so far. Experimental work with exteroceptive stimuli consistently points to effects of fear learning on perceptual discrimination acuity. In addition, clinical observations have revealed that in individuals with chronic pain perceptual discrimination is impaired, and that tactile discrimination training reduces pain. Based on these findings, we present a theoretical model of which the central tenet is that associative fear learning contributes to the development of chronic pain through impaired interoceptive and proprioceptive discrimination acuity. PMID:25603316

  5. Dual mechanisms governing reward-driven perceptual learning

    PubMed Central

    Kim, Dongho; Ling, Sam; Watanabe, Takeo

    2015-01-01

    In this review, we explore how reward signals shape perceptual learning in animals and humans. Perceptual learning is the well-established phenomenon by which extensive practice elicits selective improvement in one’s perceptual discrimination of basic visual features, such as oriented lines or moving stimuli. While perceptual learning has long been thought to rely on ‘top-down’ processes, such as attention and decision-making, a wave of recent findings suggests that these higher-level processes are, in fact, not necessary.  Rather, these recent findings indicate that reward signals alone, in the absence of the contribution of higher-level cognitive processes, are sufficient to drive the benefits of perceptual learning. Here, we will review the literature tying reward signals to perceptual learning. Based on these findings, we propose dual underlying mechanisms that give rise to perceptual learning: one mechanism that operates ‘automatically’ and is tied directly to reward signals, and another mechanism that involves more ‘top-down’, goal-directed computations. PMID:26539293

  6. Gestalt Perceptual Organization of Visual Stimuli Captures Attention Automatically: Electrophysiological Evidence

    PubMed Central

    Marini, Francesco; Marzi, Carlo A.

    2016-01-01

    The visual system leverages organizational regularities of perceptual elements to create meaningful representations of the world. One clear example of such function, which has been formalized in the Gestalt psychology principles, is the perceptual grouping of simple visual elements (e.g., lines and arcs) into unitary objects (e.g., forms and shapes). The present study sought to characterize automatic attentional capture and related cognitive processing of Gestalt-like visual stimuli at the psychophysiological level by using event-related potentials (ERPs). We measured ERPs during a simple visual reaction time task with bilateral presentations of physically matched elements with or without a Gestalt organization. Results showed that Gestalt (vs. non-Gestalt) stimuli are characterized by a larger N2pc together with enhanced ERP amplitudes of non-lateralized components (N1, N2, P3) starting around 150 ms post-stimulus onset. Thus, we conclude that Gestalt stimuli capture attention automatically and entail characteristic psychophysiological signatures at both early and late processing stages. Highlights We studied the neural signatures of the automatic processes of visual attention elicited by Gestalt stimuli. We found that a reliable early correlate of attentional capture turned out to be the N2pc component. Perceptual and cognitive processing of Gestalt stimuli is associated with larger N1, N2, and P3 PMID:27630555

  7. Gestalt Perceptual Organization of Visual Stimuli Captures Attention Automatically: Electrophysiological Evidence.

    PubMed

    Marini, Francesco; Marzi, Carlo A

    2016-01-01

    The visual system leverages organizational regularities of perceptual elements to create meaningful representations of the world. One clear example of such function, which has been formalized in the Gestalt psychology principles, is the perceptual grouping of simple visual elements (e.g., lines and arcs) into unitary objects (e.g., forms and shapes). The present study sought to characterize automatic attentional capture and related cognitive processing of Gestalt-like visual stimuli at the psychophysiological level by using event-related potentials (ERPs). We measured ERPs during a simple visual reaction time task with bilateral presentations of physically matched elements with or without a Gestalt organization. Results showed that Gestalt (vs. non-Gestalt) stimuli are characterized by a larger N2pc together with enhanced ERP amplitudes of non-lateralized components (N1, N2, P3) starting around 150 ms post-stimulus onset. Thus, we conclude that Gestalt stimuli capture attention automatically and entail characteristic psychophysiological signatures at both early and late processing stages. Highlights We studied the neural signatures of the automatic processes of visual attention elicited by Gestalt stimuli. We found that a reliable early correlate of attentional capture turned out to be the N2pc component. Perceptual and cognitive processing of Gestalt stimuli is associated with larger N1, N2, and P3.

  8. Gestalt Perceptual Organization of Visual Stimuli Captures Attention Automatically: Electrophysiological Evidence

    PubMed Central

    Marini, Francesco; Marzi, Carlo A.

    2016-01-01

    The visual system leverages organizational regularities of perceptual elements to create meaningful representations of the world. One clear example of such function, which has been formalized in the Gestalt psychology principles, is the perceptual grouping of simple visual elements (e.g., lines and arcs) into unitary objects (e.g., forms and shapes). The present study sought to characterize automatic attentional capture and related cognitive processing of Gestalt-like visual stimuli at the psychophysiological level by using event-related potentials (ERPs). We measured ERPs during a simple visual reaction time task with bilateral presentations of physically matched elements with or without a Gestalt organization. Results showed that Gestalt (vs. non-Gestalt) stimuli are characterized by a larger N2pc together with enhanced ERP amplitudes of non-lateralized components (N1, N2, P3) starting around 150 ms post-stimulus onset. Thus, we conclude that Gestalt stimuli capture attention automatically and entail characteristic psychophysiological signatures at both early and late processing stages. Highlights We studied the neural signatures of the automatic processes of visual attention elicited by Gestalt stimuli. We found that a reliable early correlate of attentional capture turned out to be the N2pc component. Perceptual and cognitive processing of Gestalt stimuli is associated with larger N1, N2, and P3

  9. Gestalt Perceptual Organization of Visual Stimuli Captures Attention Automatically: Electrophysiological Evidence.

    PubMed

    Marini, Francesco; Marzi, Carlo A

    2016-01-01

    The visual system leverages organizational regularities of perceptual elements to create meaningful representations of the world. One clear example of such function, which has been formalized in the Gestalt psychology principles, is the perceptual grouping of simple visual elements (e.g., lines and arcs) into unitary objects (e.g., forms and shapes). The present study sought to characterize automatic attentional capture and related cognitive processing of Gestalt-like visual stimuli at the psychophysiological level by using event-related potentials (ERPs). We measured ERPs during a simple visual reaction time task with bilateral presentations of physically matched elements with or without a Gestalt organization. Results showed that Gestalt (vs. non-Gestalt) stimuli are characterized by a larger N2pc together with enhanced ERP amplitudes of non-lateralized components (N1, N2, P3) starting around 150 ms post-stimulus onset. Thus, we conclude that Gestalt stimuli capture attention automatically and entail characteristic psychophysiological signatures at both early and late processing stages. Highlights We studied the neural signatures of the automatic processes of visual attention elicited by Gestalt stimuli. We found that a reliable early correlate of attentional capture turned out to be the N2pc component. Perceptual and cognitive processing of Gestalt stimuli is associated with larger N1, N2, and P3. PMID:27630555

  10. The Evolution of a Children's Domestic Violence Counseling Group: Stages and Processes

    ERIC Educational Resources Information Center

    Thompson, E. Heather

    2011-01-01

    The purpose of this qualitative case study is to illuminate the lived experiences of 4 young children between 6 and 7 years old who witnessed domestic violence while revealing the complex relationship between group process and stage development in their 18-week counseling group. Data revealed that processes occurring between and among group…

  11. Concurrent Data Elicitation Procedures, Processes, and the Early Stages of L2 Learning: A Critical Overview

    ERIC Educational Resources Information Center

    Leow, Ronald P.; Grey, Sarah; Marijuan, Silvia; Moorman, Colleen

    2014-01-01

    Given the current methodological interest in eliciting direct data on the cognitive processes L2 learners employ as they interact with L2 data during the early stages of the learning process, this article takes a critical and comparative look at three concurrent data elicitation procedures currently employed in the SLA literature: Think aloud (TA)…

  12. What makes us think? A three-stage dual-process model of analytic engagement.

    PubMed

    Pennycook, Gordon; Fugelsang, Jonathan A; Koehler, Derek J

    2015-08-01

    The distinction between intuitive and analytic thinking is common in psychology. However, while often being quite clear on the characteristics of the two processes ('Type 1' processes are fast, autonomous, intuitive, etc. and 'Type 2' processes are slow, deliberative, analytic, etc.), dual-process theorists have been heavily criticized for being unclear on the factors that determine when an individual will think analytically or rely on their intuition. We address this issue by introducing a three-stage model that elucidates the bottom-up factors that cause individuals to engage Type 2 processing. According to the model, multiple Type 1 processes may be cued by a stimulus (Stage 1), leading to the potential for conflict detection (Stage 2). If successful, conflict detection leads to Type 2 processing (Stage 3), which may take the form of rationalization (i.e., the Type 1 output is verified post hoc) or decoupling (i.e., the Type 1 output is falsified). We tested key aspects of the model using a novel base-rate task where stereotypes and base-rate probabilities cued the same (non-conflict problems) or different (conflict problems) responses about group membership. Our results support two key predictions derived from the model: (1) conflict detection and decoupling are dissociable sources of Type 2 processing and (2) conflict detection sometimes fails. We argue that considering the potential stages of reasoning allows us to distinguish early (conflict detection) and late (decoupling) sources of analytic thought. Errors may occur at both stages and, as a consequence, bias arises from both conflict monitoring and decoupling failures. PMID:26091582

  13. What makes us think? A three-stage dual-process model of analytic engagement.

    PubMed

    Pennycook, Gordon; Fugelsang, Jonathan A; Koehler, Derek J

    2015-08-01

    The distinction between intuitive and analytic thinking is common in psychology. However, while often being quite clear on the characteristics of the two processes ('Type 1' processes are fast, autonomous, intuitive, etc. and 'Type 2' processes are slow, deliberative, analytic, etc.), dual-process theorists have been heavily criticized for being unclear on the factors that determine when an individual will think analytically or rely on their intuition. We address this issue by introducing a three-stage model that elucidates the bottom-up factors that cause individuals to engage Type 2 processing. According to the model, multiple Type 1 processes may be cued by a stimulus (Stage 1), leading to the potential for conflict detection (Stage 2). If successful, conflict detection leads to Type 2 processing (Stage 3), which may take the form of rationalization (i.e., the Type 1 output is verified post hoc) or decoupling (i.e., the Type 1 output is falsified). We tested key aspects of the model using a novel base-rate task where stereotypes and base-rate probabilities cued the same (non-conflict problems) or different (conflict problems) responses about group membership. Our results support two key predictions derived from the model: (1) conflict detection and decoupling are dissociable sources of Type 2 processing and (2) conflict detection sometimes fails. We argue that considering the potential stages of reasoning allows us to distinguish early (conflict detection) and late (decoupling) sources of analytic thought. Errors may occur at both stages and, as a consequence, bias arises from both conflict monitoring and decoupling failures.

  14. Experimental Procedures and Results for Benchmark 3: Stage 2 Forming Process

    NASA Astrophysics Data System (ADS)

    Iadicola, M. A.; Foecke, T.; Stoughton, T. B.

    2005-08-01

    The Numisheet 2005 Benchmark ♯3 consists of a two stage forming process performed on four materials (three steels and one aluminum). Stage 1 consists of forming channel sections in a channel draw die with variable penetration draw beads, and is described in detail in another report. In Stage 2, described here, the samples from Stage 1 are trimmed and subjected to near plane strain Marciniak style cup test. The plane straining is performed in 0 ° and 90 ° orientations. After failure limits for the cup depths are determined, trimmed samples from Stage 1 are strained to specific cup depths (less than the depth of failure) and stresses are measured in situ using a unique X-ray diffraction technique. The results are repeatable and consistent with expectations. The goal of this benchmark is to check not only the strain achieved during a two stage forming process, but also to develop data that include the stresses achieved. These results may then be used to further test the ability of numerical models to predict not only strains but stresses during a forming process.

  15. Perceptual crossing: the simplest online paradigm

    PubMed Central

    Auvray, Malika; Rohde, Marieke

    2012-01-01

    Researchers in social cognition increasingly realize that many phenomena cannot be understood by investigating offline situations only, focusing on individual mechanisms and an observer perspective. There are processes of dynamic emergence specific to online situations, when two or more persons are engaged in a real-time interaction that are more than just the sum of the individual capacities or behaviors, and these require the study of online social interaction. Auvray et al.'s (2009) perceptual crossing paradigm offers possibly the simplest paradigm for studying such online interactions: two persons, a one-dimensional space, one bit of information, and a yes/no answer. This study has provoked a lot of resonance in different areas of research, including experimental psychology, computer/robot modeling, philosophy, psychopathology, and even in the field of design. In this article, we review and critically assess this body of literature. We give an overview of both behavioral experimental research and simulated agent modeling done using the perceptual crossing paradigm. We discuss different contexts in which work on perceptual crossing has been cited. This includes the controversy about the possible constitutive role of perceptual crossing for social cognition. We conclude with an outlook on future research possibilities, in particular those that could elucidate the link between online interaction dynamics and individual social cognition. PMID:22723776

  16. Neural repetition suppression reflects fulfilled perceptual expectations

    PubMed Central

    Summerfield, Christopher; Monti, Jim M.P.; Trittschuh, Emily H.; Mesulam, M.-Marsel; Egner, Tobias

    2009-01-01

    Stimulus-evoked neural activity is attenuated upon stimulus repetition (‘repetition suppression’), a phenomenon attributed to largely automatic processes in sensory neurons. By manipulating the likelihood of stimulus repetition, we show that repetition suppression in the human brain is reduced when stimulus repetitions are improbable (and thus, unexpected). These data suggest that repetition suppression reflects a relative reduction in top-down perceptual ‘prediction error’ when processing an expected compared to an unexpected stimulus. PMID:19160497

  17. Effect of target position on the sequential organization of processing stages.

    PubMed

    Fiori, N; Ragot, R; Renault, B

    1992-07-01

    In order to study the organization of processing stages taking place in a choice reaction time (RT) situation, the three following experimental variables were manipulated: (1) S-R compatibility; (2) movement direction; and (3) time uncertainty, these variables being known to influence distinct information processing stages. Both behavioural (RT and movement time, MT) and electrophysiological (N200 and P300 latencies) indices of processing time were analysed. All three experimental variables showed significant, additive effects on RT. Only the preparatory period had a significant effect on N200 and on P300 latencies. These results support the construction of a serial model. Furthermore, the analysis of the time intervals between electrophysiological and behavioural indices allows one to infer the relative order of the different stages in this model, as follows: motor pre-initiation, motor pre-programming, response selection and programming, and motor initiation.

  18. Two stages of parafoveal processing during reading: Evidence from a display change detection task.

    PubMed

    Angele, Bernhard; Slattery, Timothy J; Rayner, Keith

    2016-08-01

    We used a display change detection paradigm (Slattery, Angele, & Rayner Human Perception and Performance, 37, 1924-1938 2011) to investigate whether display change detection uses orthographic regularity and whether detection is affected by the processing difficulty of the word preceding the boundary that triggers the display change. Subjects were significantly more sensitive to display changes when the change was from a nonwordlike preview than when the change was from a wordlike preview, but the preview benefit effect on the target word was not affected by whether the preview was wordlike or nonwordlike. Additionally, we did not find any influence of preboundary word frequency on display change detection performance. Our results suggest that display change detection and lexical processing do not use the same cognitive mechanisms. We propose that parafoveal processing takes place in two stages: an early, orthography-based, preattentional stage, and a late, attention-dependent lexical access stage.

  19. Two stages of parafoveal processing during reading: Evidence from a display change detection task.

    PubMed

    Angele, Bernhard; Slattery, Timothy J; Rayner, Keith

    2016-08-01

    We used a display change detection paradigm (Slattery, Angele, & Rayner Human Perception and Performance, 37, 1924-1938 2011) to investigate whether display change detection uses orthographic regularity and whether detection is affected by the processing difficulty of the word preceding the boundary that triggers the display change. Subjects were significantly more sensitive to display changes when the change was from a nonwordlike preview than when the change was from a wordlike preview, but the preview benefit effect on the target word was not affected by whether the preview was wordlike or nonwordlike. Additionally, we did not find any influence of preboundary word frequency on display change detection performance. Our results suggest that display change detection and lexical processing do not use the same cognitive mechanisms. We propose that parafoveal processing takes place in two stages: an early, orthography-based, preattentional stage, and a late, attention-dependent lexical access stage. PMID:26769246

  20. Catalytic two-stage coal hydrogenation process using extinction recycle of heavy liquid fraction

    DOEpatents

    MacArthur, James B.; Comolli, Alfred G.; McLean, Joseph B.

    1989-01-01

    A process for catalytic two-stage hydrogenation and liquefaction of coal with selective extinction recycle of all heavy liquid fractions boiling above a distillation cut point of about 600.degree.-750.degree. F. to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal feed is slurried with a process-derived liquid solvent normally boiling above about 650.degree. F. and fed into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils. The first stage reactor is maintained at 710.degree.-800.degree. F. temperature, 1000-4000 psig hydrogen partial pressure, and 10-90 lb/hr per ft.sup.3 catalyst space velocity. Partially hydrogenated material withdrawn from the first stage reaction zone is passed directly to the second stage catalytic reaction zone maintained at 760.degree.-860.degree. F. temperature for further hydrogenation and hydroconversion reactions. A 600.degree.-750.degree. F..sup.+ fraction containing 0-20 W % unreacted coal and ash solids is recycled to the coal slurrying step. If desired, the cut point lower boiling fraction can be further catalytically hydrotreated. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, to provide significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of hydrocarbon gases, and no net production of undesirable heavy oils and residuum materials.

  1. Catalytic two-stage coal hydrogenation process using extinction recycle of heavy liquid fraction

    DOEpatents

    MacArthur, J.B.; Comolli, A.G.; McLean, J.B.

    1989-10-17

    A process is described for catalytic two-stage hydrogenation and liquefaction of coal with selective extinction recycle of all heavy liquid fractions boiling above a distillation cut point of about 600--750 F to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal feed is slurried with a process-derived liquid solvent normally boiling above about 650 F and fed into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils. The first stage reactor is maintained at 710--800 F temperature, 1,000--4,000 psig hydrogen partial pressure, and 10-90 lb/hr per ft[sup 3] catalyst space velocity. Partially hydrogenated material withdrawn from the first stage reaction zone is passed directly to the second stage catalytic reaction zone maintained at 760--860 F temperature for further hydrogenation and hydroconversion reactions. A 600--750 F[sup +] fraction containing 0--20 W % unreacted coal and ash solids is recycled to the coal slurrying step. If desired, the cut point lower boiling fraction can be further catalytically hydrotreated. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, to provide significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of hydrocarbon gases, and no net production of undesirable heavy oils and residuum materials. 2 figs.

  2. Perceptual Constraints in Phonotactic Learning

    ERIC Educational Resources Information Center

    Endress, Ansgar D.; Mehler, Jacques

    2010-01-01

    Structural regularities in language have often been attributed to symbolic or statistical general purpose computations, whereas perceptual factors influencing such generalizations have received less interest. Here, we use phonotactic-like constraints as a case study to ask whether the structural properties of specific perceptual and memory…

  3. Perceptual shift in bilingualism: brain potentials reveal plasticity in pre-attentive colour perception.

    PubMed

    Athanasopoulos, Panos; Dering, Benjamin; Wiggett, Alison; Kuipers, Jan-Rouke; Thierry, Guillaume

    2010-09-01

    The validity of the linguistic relativity principle continues to stimulate vigorous debate and research. The debate has recently shifted from the behavioural investigation arena to a more biologically grounded field, in which tangible physiological evidence for language effects on perception can be obtained. Using brain potentials in a colour oddball detection task with Greek and English speakers, a recent study suggests that language effects may exist at early stages of perceptual integration [Thierry, G., Athanasopoulos, P., Wiggett, A., Dering, B., & Kuipers, J. (2009). Unconscious effects of language-specific terminology on pre-attentive colour perception. Proceedings of the National Academy of Sciences, 106, 4567-4570]. In this paper, we test whether in Greek speakers exposure to a new cultural environment (UK) with contrasting colour terminology from their native language affects early perceptual processing as indexed by an electrophysiological correlate of visual detection of colour luminance. We also report semantic mapping of native colour terms and colour similarity judgements. Results reveal convergence of linguistic descriptions, cognitive processing, and early perception of colour in bilinguals. This result demonstrates for the first time substantial plasticity in early, pre-attentive colour perception and has important implications for the mechanisms that are involved in perceptual changes during the processes of language learning and acculturation.

  4. Russian refiner tests new one-stage H[sub 2]S removal process

    SciTech Connect

    Not Available

    1994-03-07

    The Institute of Catalysis, Novosibirsk, Russia, has developed a new technology for purifying gas streams containing hydrogen sulfide. The one-stage process was tested at BashSKTP Concern Grozneftekhim's refinery in Ufa, Russia, near the southern Ural Mountains. In a pilot-size reactor, the process achieved 99% conversion of total H[sub 2]S and 98% selectivity to sulfur. The process and test results are described briefly.

  5. Detecting perceptual groupings in textures by continuity considerations

    NASA Technical Reports Server (NTRS)

    Greene, Richard J.

    1990-01-01

    A generalization is presented for the second derivative of a Gaussian D(sup 2)G operator to apply to problems of perceptual organization involving textures. Extensions to other problems of perceptual organization are evident and a new research direction can be established. The technique presented is theoretically pleasing since it has the potential of unifying the entire area of image segmentation under the mathematical notion of continuity and presents a single algorithm to form perceptual groupings where many algorithms existed previously. The eventual impact on both the approach and technique of image processing segmentation operations could be significant.

  6. Sustained Perceptual Deficits from Transient Sensory Deprivation

    PubMed Central

    Sanes, Dan H.

    2015-01-01

    displays an increased vulnerability to the sensory environment. Here, we identify a precise developmental window during which mild hearing loss affects the maturation of an auditory perceptual cue that is known to support animal communication, including human speech. Furthermore, animals reared with transient hearing loss display deficits in perceptual learning. Our results suggest that speech and language delays associated with transient or permanent childhood hearing loss may be accounted for, in part, by deficits in central auditory processing mechanisms. PMID:26224865

  7. Catalytic multi-stage process for hydroconversion and refining hydrocarbon feeds

    DOEpatents

    Comolli, Alfred G.; Lee, Lap-Keung

    2001-01-01

    A multi-stage catalytic hydrogenation and hydroconversion process for heavy hydrocarbon feed materials such as coal, heavy petroleum fractions, and plastic waste materials. In the process, the feedstock is reacted in a first-stage, back-mixed catalytic reactor with a highly dispersed iron-based catalyst having a powder, gel or liquid form. The reactor effluent is pressure-reduced, vapors and light distillate fractions are removed overhead, and the heavier liquid fraction is fed to a second stage back-mixed catalytic reactor. The first and second stage catalytic reactors are operated at 700-850.degree. F. temperature, 1000-3500 psig hydrogen partial pressure and 20-80 lb./hr per ft.sup.3 reactor space velocity. The vapor and light distillates liquid fractions removed from both the first and second stage reactor effluent streams are combined and passed to an in-line, fixed-bed catalytic hydrotreater for heteroatom removal and for producing high quality naphtha and mid-distillate or a full-range distillate product. The remaining separator bottoms liquid fractions are distilled at successive atmospheric and vacuum pressures, low and intermediate-boiling hydrocarbon liquid products are withdrawn, and heavier distillate fractions are recycled and further upgraded to provide additional low-boiling hydrocarbon liquid products. This catalytic multistage hydrogenation process provides improved flexibility for hydroprocessing the various carbonaceous feedstocks and adjusting to desired product structures and for improved economy of operations.

  8. Performance analysis of RDF gasification in a two stage fluidized bed-plasma process.

    PubMed

    Materazzi, M; Lettieri, P; Taylor, R; Chapman, C

    2016-01-01

    The major technical problems faced by stand-alone fluidized bed gasifiers (FBG) for waste-to gas applications are intrinsically related to the composition and physical properties of waste materials, such as RDF. The high quantity of ash and volatile material in RDF can provide a decrease in thermal output, create high ash clinkering, and increase emission of tars and CO2, thus affecting the operability for clean syngas generation at industrial scale. By contrast, a two-stage process which separates primary gasification and selective tar and ash conversion would be inherently more forgiving and stable. This can be achieved with the use of a separate plasma converter, which has been successfully used in conjunction with conventional thermal treatment units, for the ability to 'polish' the producer gas by organic contaminants and collect the inorganic fraction in a molten (and inert) state. This research focused on the performance analysis of a two-stage fluid bed gasification-plasma process to transform solid waste into clean syngas. Thermodynamic assessment using the two-stage equilibrium method was carried out to determine optimum conditions for the gasification of RDF and to understand the limitations and influence of the second stage on the process performance (gas heating value, cold gas efficiency, carbon conversion efficiency), along with other parameters. Comparison with a different thermal refining stage, i.e. thermal cracking (via partial oxidation) was also performed. The analysis is supported by experimental data from a pilot plant.

  9. Performance analysis of RDF gasification in a two stage fluidized bed-plasma process.

    PubMed

    Materazzi, M; Lettieri, P; Taylor, R; Chapman, C

    2016-01-01

    The major technical problems faced by stand-alone fluidized bed gasifiers (FBG) for waste-to gas applications are intrinsically related to the composition and physical properties of waste materials, such as RDF. The high quantity of ash and volatile material in RDF can provide a decrease in thermal output, create high ash clinkering, and increase emission of tars and CO2, thus affecting the operability for clean syngas generation at industrial scale. By contrast, a two-stage process which separates primary gasification and selective tar and ash conversion would be inherently more forgiving and stable. This can be achieved with the use of a separate plasma converter, which has been successfully used in conjunction with conventional thermal treatment units, for the ability to 'polish' the producer gas by organic contaminants and collect the inorganic fraction in a molten (and inert) state. This research focused on the performance analysis of a two-stage fluid bed gasification-plasma process to transform solid waste into clean syngas. Thermodynamic assessment using the two-stage equilibrium method was carried out to determine optimum conditions for the gasification of RDF and to understand the limitations and influence of the second stage on the process performance (gas heating value, cold gas efficiency, carbon conversion efficiency), along with other parameters. Comparison with a different thermal refining stage, i.e. thermal cracking (via partial oxidation) was also performed. The analysis is supported by experimental data from a pilot plant. PMID:26184896

  10. Temporal integration at consecutive processing stages in the auditory pathway of the grasshopper

    PubMed Central

    Ronacher, Bernhard

    2015-01-01

    Temporal integration in the auditory system of locusts was quantified by presenting single clicks and click pairs while performing intracellular recordings. Auditory neurons were studied at three processing stages, which form a feed-forward network in the metathoracic ganglion. Receptor neurons and most first-order interneurons (“local neurons”) encode the signal envelope, while second-order interneurons (“ascending neurons”) tend to extract more complex, behaviorally relevant sound features. In different neuron types of the auditory pathway we found three response types: no significant temporal integration (some ascending neurons), leaky energy integration (receptor neurons and some local neurons), and facilitatory processes (some local and ascending neurons). The receptor neurons integrated input over very short time windows (<2 ms). Temporal integration on longer time scales was found at subsequent processing stages, indicative of within-neuron computations and network activity. These different strategies, realized at separate processing stages and in parallel neuronal pathways within one processing stage, could enable the grasshopper's auditory system to evaluate longer time windows and thus to implement temporal filters, while at the same time maintaining a high temporal resolution. PMID:25609104

  11. Subcortical correlates of auditory perceptual organization in humans.

    PubMed

    Yamagishi, Shimpei; Otsuka, Sho; Furukawa, Shigeto; Kashino, Makio

    2016-09-01

    To make sense of complex auditory scenes, the auditory system sequentially organizes auditory components into perceptual objects or streams. In the conventional view of this process, the cortex plays a major role in perceptual organization, and subcortical mechanisms merely provide the cortex with acoustical features. Here, we show that the neural activities of the brainstem are linked to perceptual organization, which alternates spontaneously for human listeners without any stimulus change. The stimulus used in the experiment was an unchanging sequence of repeated triplet tones, which can be interpreted as either one or two streams. Listeners were instructed to report the perceptual states whenever they experienced perceptual switching between one and two streams throughout the stimulus presentation. Simultaneously, we recorded event related potentials with scalp electrodes. We measured the frequency-following response (FFR), which is considered to originate from the brainstem. We also assessed thalamo-cortical activity through the middle-latency response (MLR). The results demonstrate that the FFR and MLR varied with the state of auditory stream perception. In addition, we found that the MLR change precedes the FFR change with perceptual switching from a one-stream to a two-stream percept. This suggests that there are top-down influences on brainstem activity from the thalamo-cortical pathway. These findings are consistent with the idea of a distributed, hierarchical neural network for perceptual organization and suggest that the network extends to the brainstem level. PMID:27371867

  12. Exploring Perceptual Skills in Children with Autism Spectrum Disorders: From Target Detection to Dynamic Perceptual Discrimination

    ERIC Educational Resources Information Center

    Miller, Louisa; McGonigle-Chalmers, Maggie

    2014-01-01

    Perceptual processing in autism is associated with both "strengths" and "weaknesses" but within a literature that varies widely in terms of the assessments used. We report data from 12 children with autism spectrum disorders (ASD) and 12 age and IQ matched neurotypical controls tested on a set of tasks using the same stimuli…

  13. Perceptual Discrimination in Static and Dynamic Noise: The Temporal Relation between Perceptual Encoding and Decision Making

    ERIC Educational Resources Information Center

    Ratcliff, Roger; Smith, Philip L.

    2010-01-01

    The authors report 9 new experiments and reanalyze 3 published experiments that investigate factors affecting the time course of perceptual processing and its effects on subsequent decision making. Stimuli in letter-discrimination and brightness-discrimination tasks were degraded with static and dynamic noise. The onset and the time course of…

  14. A two-stage enzymatic process for synthesis of extremely pure high oleic glycerol monooleate.

    PubMed

    Zhu, Qisi; Li, Tie; Wang, Yonghua; Yang, Bo; Ma, Yongjun

    2011-02-01

    This paper presents a research interest concentrating on aims to establish a feasible industrial process for enzymatic production of highly pure glycerol monooleate (GMO). The synthesis of high oleic glycerol monooleate by enzymatic glycerolysis of high oleic sunflower oil, using Novozyme 435 as the biocatalyst, in a binary solvent mixture of tert-butanol and tert-pentanol (80/20, v/v), at a lab scale has been studied. A yield of 75.31% monoacylglycerol has been achieved at the first stage. A yield of 93.3% GMO was finally reached after further purification at the second stage. To evaluate the possibility of the process for industrialization, production of GMO was performed at a pilot-plant scale under the correspondingly adjusted conditions. A yield of 68.17% and 93.4% of GMO was obtained, respectively, at the end of the three stages.

  15. From wastewater to bioenergy and biochemicals via two-stage bioconversion processes: a future paradigm.

    PubMed

    Li, Wen-Wei; Yu, Han-Qing

    2011-01-01

    Recovery of bioenergy and biochemicals from wastewater has attracted growing and widespread interests. In this respect, two-stage bioconversion process (TSBP) offers an appealing avenue to achieve stepwise and directional substrate conversion in separated stages. Such a biosystem not only enables enhanced degradation of organics, but also favors a high product yield and quality. Various TSBRs have been developed for the production of methane, hydrogen, electricity, bioplastics, bioflocculants, biopesticides, biosurfactants and other value-added products, demonstrating marked advantages over the conventional one-stage processes. It represents a promising, and likely the sole viable, paradigm for future application. However, there are also many remaining challenges. This paper provides an overview of the various TSBPs, introduces the recent advances, and discusses the major challenges and the future perspectives for practical application. PMID:21884782

  16. Perceptual discrimination in fear generalization: Mechanistic and clinical implications.

    PubMed

    Struyf, Dieter; Zaman, Jonas; Vervliet, Bram; Van Diest, Ilse

    2015-12-01

    For almost a century, Pavlovian conditioning is the imperative experimental paradigm to investigate the development and generalization of fear. However, despite the rich research tradition, the conceptualization of fear generalization has remained somewhat ambiguous. In this selective review, we focus explicitly on some challenges with the current operationalization of fear generalization and their impact on the ability to make inferences on its clinical potential and underlying processes. The main conclusion is that, despite the strong evidence that learning influences perception, current research has largely neglected the role of perceptual discriminability and its plasticity in fear generalization. We propose an alternative operationalization of generalization, where the essence is that Pavlovian conditioning itself influences the breadth of fear generalization via learning-related changes in perceptual discriminability. Hence a conceptualization of fear generalization is incomplete without an in-depth analysis of processes of perceptual discriminability. Furthermore, this highlights perceptual learning and discriminability as important future targets for pre-clinical and clinical research.

  17. Relationship between early and late stages of information processing: an event-related potential study

    PubMed Central

    Portella, Claudio; Machado, Sergio; Arias-Carrión, Oscar; Sack, Alexander T.; Silva, Julio Guilherme; Orsini, Marco; Leite, Marco Antonio Araujo; Silva, Adriana Cardoso; Nardi, Antonio E.; Cagy, Mauricio; Piedade, Roberto; Ribeiro, Pedro

    2012-01-01

    The brain is capable of elaborating and executing different stages of information processing. However, exactly how these stages are processed in the brain remains largely unknown. This study aimed to analyze the possible correlation between early and late stages of information processing by assessing the latency to, and amplitude of, early and late event-related potential (ERP) components, including P200, N200, premotor potential (PMP) and P300, in healthy participants in the context of a visual oddball paradigm. We found a moderate positive correlation among the latency of P200 (electrode O2), N200 (electrode O2), PMP (electrode C3), P300 (electrode PZ) and the reaction time (RT). In addition, moderate negative correlation between the amplitude of P200 and the latencies of N200 (electrode O2), PMP (electrode C3), P300 (electrode PZ) was found. Therefore, we propose that if the secondary processing of visual input (P200 latency) occurs faster, the following will also happen sooner: discrimination and classification process of this input (N200 latency), motor response processing (PMP latency), reorganization of attention and working memory update (P300 latency), and RT. N200, PMP, and P300 latencies are also anticipated when higher activation level of occipital areas involved in the secondary processing of visual input rise (P200 amplitude). PMID:23355929

  18. Associative (prosop)agnosia without (apparent) perceptual deficits: a case-study.

    PubMed

    Anaki, David; Kaufman, Yakir; Freedman, Morris; Moscovitch, Morris

    2007-04-01

    In associative agnosia early perceptual processing of faces or objects are considered to be intact, while the ability to access stored semantic information about the individual face or object is impaired. Recent claims, however, have asserted that associative agnosia is also characterized by deficits at the perceptual level, which are too subtle to be detected by current neuropsychological tests. Thus, the impaired identification of famous faces or common objects in associative agnosia stems from difficulties in extracting the minute perceptual details required to identify a face or an object. In the present study, we report the case of a patient DBO with a left occipital infarct, who shows impaired object and famous face recognition. Despite his disability, he exhibits a face inversion effect, and is able to select a famous face from among non-famous distractors. In addition, his performance is normal in an immediate and delayed recognition memory for faces, whose external features were deleted. His deficits in face recognition are apparent only when he is required to name a famous face, or select two faces from among a triad of famous figures based on their semantic relationships (a task which does not require access to names). The nature of his deficits in object perception and recognition are similar to his impairments in the face domain. This pattern of behavior supports the notion that apperceptive and associative agnosia reflect distinct and dissociated deficits, which result from damage to different stages of the face and object recognition process.

  19. Monitoring the censored lognormal reliability data in a three-stage process using AFT model

    NASA Astrophysics Data System (ADS)

    Goodarzi, Azam; Amiri, Amirhossein; Asadzadeh, Shervin

    2016-09-01

    Improving the product reliability is the main concern in both manufacturing and service processes which is obtained by monitoring the reliability-related quality characteristics. Nowadays, products or services are the result of processes with dependent stages referred to as multistage processes. In these processes, the quality characteristic in each stage is affected by the quality characteristic in the previous stages known as cascade property. Two regression-adjusted control schemes are applied to monitor the output quality variables of interest. Moreover, censoring is among the main limitations while monitoring the reliability-related quality characteristics, causing not to record the real values of some observations. Hence, the right censored observations are used to extend monitoring schemes under both the fixed- and variable-competing risks. In this paper, the accelerated failure time (AFT) is used to relate the reliability-related quality characteristic with lognormal distribution to the incoming variables. Then, two cause-selecting control charts are developed to monitor outgoing quality variables when censoring happens in each reliability-related stage. The performance of the control charts is evaluated and compared through extensive simulation studies under the censored and non-censored scenarios.

  20. Early-stage visual processing abnormalities in high-functioning autism spectrum disorder (ASD)

    PubMed Central

    Baruth, Joshua M.; Casanova, Manuel F.; Sears, Lonnie; Sokhadze, Estate

    2012-01-01

    It has been reported that individuals with autism spectrum disorder (ASD) have abnormal responses to the sensory environment. For these individuals sensory overload can impair functioning, raise physiological stress, and adversely affect social interaction. Early-stage (i.e. within 200ms of stimulus onset) auditory processing abnormalities have been widely examined in ASD using event-related potentials (ERP), while ERP studies investigating early-stage visual processing in ASD are less frequent. We wanted to test the hypothesis of early-stage visual processing abnormalities in ASD by investigating ERPs elicited in a visual oddball task using illusory figures. Our results indicate that individuals with ASD have abnormally large cortical responses to task irrelevant stimuli over both parieto-occipital and frontal regions-of-interest (ROI) during early stages of visual processing compared to the control group. Furthermore, ASD patients showed signs of an overall disruption in stimulus discrimination, and had a significantly higher rate of motor response errors. PMID:22563527

  1. Wallas' Four-Stage Model of the Creative Process: More than Meets the Eye?

    ERIC Educational Resources Information Center

    Sadler-Smith, Eugene

    2015-01-01

    Based on a detailed reading of Graham Wallas' "Art of Thought" (1926) it is argued that his four-stage model of the creative process (Preparation, Incubation, Illumination, Verification), in spite of holding sway as a conceptual anchor for many creativity researchers, does not reflect accurately Wallas' full account of the creative…

  2. Quasi-steady stages in the process of premixed flame acceleration in narrow channels

    NASA Astrophysics Data System (ADS)

    Valiev, D. M.; Bychkov, V.; Akkerman, V.; Eriksson, L.-E.; Law, C. K.

    2013-09-01

    The present paper addresses the phenomenon of spontaneous acceleration of a premixed flame front propagating in micro-channels, with subsequent deflagration-to-detonation transition. It has recently been shown experimentally [M. Wu, M. Burke, S. Son, and R. Yetter, Proc. Combust. Inst. 31, 2429 (2007)], 10.1016/j.proci.2006.08.098, computationally [D. Valiev, V. Bychkov, V. Akkerman, and L.-E. Eriksson, Phys. Rev. E 80, 036317 (2009)], 10.1103/PhysRevE.80.036317, and analytically [V. Bychkov, V. Akkerman, D. Valiev, and C. K. Law, Phys. Rev. E 81, 026309 (2010)], 10.1103/PhysRevE.81.026309 that the flame acceleration undergoes different stages, from an initial exponential regime to quasi-steady fast deflagration with saturated velocity. The present work focuses on the final saturation stages in the process of flame acceleration, when the flame propagates with supersonic velocity with respect to the channel walls. It is shown that an intermediate stage may occur during acceleration with quasi-steady velocity, noticeably below the Chapman-Jouguet deflagration speed. The intermediate stage is followed by additional flame acceleration and subsequent saturation to the Chapman-Jouguet deflagration regime. We elucidate the intermediate stage by the joint effect of gas pre-compression ahead of the flame front and the hydraulic resistance. The additional acceleration is related to viscous heating at the channel walls, being of key importance at the final stages. The possibility of explosion triggering is also demonstrated.

  3. Determination of wastewater LC50 of the different process stages of the textile industry.

    PubMed

    Villegas-Navarro, A; Ramírez-M, Y; Salvador-S, M S; Gallardo, J M

    2001-01-01

    Textile plants are very important sources of toxic discharges. The purpose of the research described in this paper was to use bioassays with daphnids to determine the LC50 values of textile wastewater samples taken from different stages of the finishing textile industry. Toxicity due to dyeing, chlorination, and the absence of adequate physicochemical conditions for daphnid survival were considered. Wastewater samples corresponding to each process stage were collected at five finishing textile industries and assayed according to previously published procedures. The sensitivity of daphnids to chemicals was assayed using sodium dodecyl sulfate and was similar to other reports (14.6+/-6.8 vs 14.5+/-2.3 mg/L). All effluents from the five company samples were toxic in terms of LC50 and exhibited very high toxicity with acute toxicity unit (ATU) levels between 2.2 and 960, indicating that the five textile industries produced toxic water. The sensory characteristics indicated that the dyes contributed to overall sample toxicity at all process stages. The most toxic contaminant seemed to be ClO- at levels between 0.2 and 6.8 mg/L, suggesting that further research is needed on the economic costs of stage-by-stage and total effluent treatments.

  4. Perceptual learning in sensorimotor adaptation.

    PubMed

    Darainy, Mohammad; Vahdat, Shahabeddin; Ostry, David J

    2013-11-01

    Motor learning often involves situations in which the somatosensory targets of movement are, at least initially, poorly defined, as for example, in learning to speak or learning the feel of a proper tennis serve. Under these conditions, motor skill acquisition presumably requires perceptual as well as motor learning. That is, it engages both the progressive shaping of sensory targets and associated changes in motor performance. In the present study, we test the idea that perceptual learning alters somatosensory function and in so doing produces changes to human motor performance and sensorimotor adaptation. Subjects in these experiments undergo perceptual training in which a robotic device passively moves the subject's arm on one of a set of fan-shaped trajectories. Subjects are required to indicate whether the robot moved the limb to the right or the left and feedback is provided. Over the course of training both the perceptual boundary and acuity are altered. The perceptual learning is observed to improve both the rate and extent of learning in a subsequent sensorimotor adaptation task and the benefits persist for at least 24 h. The improvement in the present studies varies systematically with changes in perceptual acuity and is obtained regardless of whether the perceptual boundary shift serves to systematically increase or decrease error on subsequent movements. The beneficial effects of perceptual training are found to be substantially dependent on reinforced decision-making in the sensory domain. Passive-movement training on its own is less able to alter subsequent learning in the motor system. Overall, this study suggests perceptual learning plays an integral role in motor learning.

  5. Early-stage comparative sustainability assessment of new bio-based processes.

    PubMed

    Patel, Akshay D; Meesters, Koen; den Uil, Herman; de Jong, Ed; Worrell, Ernst; Patel, Martin K

    2013-09-01

    Our increasing demand for materials and energy has put critical roadblocks on our path towards a sustainable society. To remove these roadblocks, it is important to engage in smart research and development (R&D). We present an early-stage sustainability assessment framework that is used to analyze eight new bio-based process alternatives developed within the CatchBio research consortium in the Netherlands. This assessment relies on a multi-criteria approach, integrating the performance of chemical conversions based on five indicators into an index value. These indicators encompass economics, environmental impact, hazards and risks thereby incorporating elements of green chemistry principles, and techno-economic and life cycle assessments. The analyzed bio-based options target the production of fuels and chemicals through chemical catalysis. For each bio-based process, two R&D stages (current laboratory and expected future) are assessed against a comparable conventional process. The multi-criteria assessment in combination with the uncertainty and scenario analysis shows that the chemical production processes using biomass as feedstock can provide potential sustainability benefits over conventional alternatives. However, further development is necessary to realize the potential benefits from biomass gasification and pyrolysis processes for fuel production. This early stage assessment is intended as an input for R&D decision making to support optimal allocation and utilization of resources to further develop promising bio-based processes. PMID:24078179

  6. Sensory shelf life estimation of minimally processed lettuce considering two stages of consumers' decision-making process.

    PubMed

    Ares, Gastón; Giménez, Ana; Gámbaro, Adriana

    2008-01-01

    The aim of the present work was to study the influence of context, particularly the stage of the decision-making process (purchase vs consumption stage), on sensory shelf life of minimally processed lettuce. Leaves of butterhead lettuce were placed in common polypropylene bags and stored at 5, 10 and 15 degrees C. Periodically, a panel of six assessors evaluated the appearance of the samples, and a panel of 40 consumers evaluated their appearance and answered "yes" or "no" to the questions: "Imagine you are in a supermarket, you want to buy a minimally processed lettuce, and you find a package of lettuce with leaves like this, would you normally buy it?" and "Imagine you have this leaf of lettuce stored in your refrigerator, would you normally consume it?". Survival analysis was used to calculate the shelf lives of minimally processed lettuce, considering both decision-making stages. Shelf lives estimated considering rejection to purchase were significantly lower than those estimated considering rejection to consume. Therefore, in order to be conservative and assure the products' quality, shelf life should be estimated considering consumers' rejection to purchase instead of rejection to consume, as traditionally has been done. On the other hand, results from logistic regressions of consumers' rejection percentage as a function of the evaluated appearance attributes suggested that consumers considered them differently while deciding whether to purchase or to consume minimally processed lettuce.

  7. Coupled finite element simulation and optimization of single- and multi-stage sheet-forming processes

    NASA Astrophysics Data System (ADS)

    Tamasco, Cynthia M.; Rais-Rohani, Masoud; Buijk, Arjaan

    2013-03-01

    This article presents the development and application of a coupled finite element simulation and optimization framework that can be used for design and analysis of sheet-forming processes of varying complexity. The entire forming process from blank gripping and deep drawing to tool release and springback is modelled. The dies, holders, punch and workpiece are modelled with friction, temperature, holder force and punch speed controlled in the process simulation. Both single- and multi-stage sheet-forming processes are investigated. Process simulation is coupled with a nonlinear gradient-based optimization approach for optimizing single or multiple design objectives with imposed sheet-forming response constraints. A MATLAB program is developed and used for data-flow management between process simulation and optimization codes. Thinning, springback, damage and forming limit diagram are used to define failure in the forming process design optimization. Design sensitivity analysis and optimization results of the example problems are presented and discussed.

  8. NASA Ares 1 Crew Launch Vehicle Upper Stage Configuration Selection Process

    NASA Technical Reports Server (NTRS)

    Cook, Jerry R.

    2006-01-01

    The Upper Stage Element of NASA s Ares I Crew Launch Vehicle (CLV) is a "clean-sheet" approach that is being designed and developed in-house, with Element management at MSFC. The USE concept is a self-supporting cylindrical structure, approximately 115 long and 216" in diameter. While the Reusable Solid Rocket Booster (RSRB) design has changed since the CLV inception, the Upper Stage Element design has remained essentially a clean-sheet approach. Although a clean-sheet upper stage design inherently carries more risk than a modified design, it does offer many advantages: a design for increased reliability; built-in extensibility to allow for commonality/growth without major redesign; and incorporation of state-of-the-art materials, hardware, and design, fabrication, and test techniques and processes to facilitate a potentially better, more reliable system.

  9. Discrete blasts in granular material yield two-stage process of cavitation and granular fountaining

    NASA Astrophysics Data System (ADS)

    Andrews, Robin; White, James; Dürig, Tobi; Zimanowski, Bernd

    2014-05-01

    A discrete blast within granular material, such as a single subterranean explosion within a debris-filled diatreme structure, is typically considered to produce a single uprush of material. Our experiments demonstrate that apparent "debris jet deposits" can be formed by a two-stage process of cavitation and subsequent granular fountaining. Bench-scale experiments reported here demonstrate that for a range of overpressures and depths, individual, discrete, buried gas blasts open space and expel particles from the blast site in two largely decoupled stages. Expanding gas initially pierces material nearest the blast source to open a cavity above it; then a fountain of grains rises from the source into the cavity. This staged motion dynamically segregates source grains from host-material grains, and the rates of cavity opening vs. fountain rise show a power-law decay relationship with initial pressure. Our experimental analysis has implications for maar-diatreme systems, field-scale detonation experiments, and underground nuclear testing.

  10. Discrete blasts in granular material yield two-stage process of cavitation and granular fountaining

    NASA Astrophysics Data System (ADS)

    Andrews, Robin G.; White, James D. L.; Dürig, Tobi; Zimanowski, Bernd

    2014-01-01

    A discrete blast within granular material, such as a single subterranean explosion within a debris-filled diatreme structure, is typically considered to produce a single uprush of material. Our experiments demonstrate that apparent "debris jet deposits" can be formed by a two-stage process of cavitation and subsequent granular fountaining. Bench-scale experiments reported here demonstrate that for a range of overpressures and depths, individual, discrete, buried gas blasts open space and expel particles from the blast site in two largely decoupled stages. Expanding gas initially pierces material nearest the blast source to open a cavity above it; then a fountain of grains rises from the source into the cavity. This staged motion dynamically segregates source grains from host-material grains, and the rates of cavity opening versus fountain rise show a power law decay relationship with initial pressure. Our experimental analysis has implications for maar-diatreme systems, field-scale detonation experiments, and underground nuclear testing.

  11. FRAS1-related extracellular matrix 3 (FREM3) single-nucleotide polymorphism effects on gene expression, amygdala reactivity and perceptual processing speed: An accelerated aging pathway of depression risk.

    PubMed

    Nikolova, Yuliya S; Iruku, Swetha P; Lin, Chien-Wei; Conley, Emily Drabant; Puralewski, Rachel; French, Beverly; Hariri, Ahmad R; Sibille, Etienne

    2015-01-01

    The A allele of the FRAS1-related extracellular matrix protein 3 (FREM3) rs7676614 single nucleotide polymorphism (SNP) was linked to major depressive disorder (MDD) in an early genome-wide association study (GWAS), and to symptoms of psychomotor retardation in a follow-up investigation. In line with significant overlap between age- and depression-related molecular pathways, parallel work has shown that FREM3 expression in postmortem human brain decreases with age. Here, we probe the effect of rs7676614 on amygdala reactivity and perceptual processing speed, both of which are altered in depression and aging. Amygdala reactivity was assessed using a face-matching BOLD fMRI paradigm in 365 Caucasian participants in the Duke Neurogenetics Study (DNS) (192 women, mean age 19.7 ± 1.2). Perceptual processing speed was indexed by reaction times in the same task and the Trail Making Test (TMT). The effect of rs7676614 on FREM3 mRNA brain expression levels was probed in a postmortem cohort of 169 Caucasian individuals (44 women, mean age 50.8 ± 14.9). The A allele of rs7676614 was associated with blunted amygdala reactivity to faces, slower reaction times in the face-matching condition (p < 0.04), as well as marginally slower performance on TMT Part B (p = 0.056). In the postmortem cohort, the T allele of rs6537170 (proxy for the rs7676614 A allele), was associated with trend-level reductions in gene expression in Brodmann areas 11 and 47 (p = 0.066), reminiscent of patterns characteristic of older age. The low-expressing allele of another FREM3 SNP (rs1391187) was similarly associated with reduced amygdala reactivity and slower TMT Part B speed, in addition to reduced BA47 activity and extraversion (p < 0.05). Together, these results suggest common genetic variation associated with reduced FREM3 expression may confer risk for a subtype of depression characterized by reduced reactivity to environmental stimuli and slower perceptual processing speed, possibly suggestive of

  12. FRAS1-related extracellular matrix 3 (FREM3) single-nucleotide polymorphism effects on gene expression, amygdala reactivity and perceptual processing speed: An accelerated aging pathway of depression risk

    PubMed Central

    Nikolova, Yuliya S.; Iruku, Swetha P.; Lin, Chien-Wei; Conley, Emily Drabant; Puralewski, Rachel; French, Beverly; Hariri, Ahmad R.; Sibille, Etienne

    2015-01-01

    The A allele of the FRAS1-related extracellular matrix protein 3 (FREM3) rs7676614 single nucleotide polymorphism (SNP) was linked to major depressive disorder (MDD) in an early genome-wide association study (GWAS), and to symptoms of psychomotor retardation in a follow-up investigation. In line with significant overlap between age- and depression-related molecular pathways, parallel work has shown that FREM3 expression in postmortem human brain decreases with age. Here, we probe the effect of rs7676614 on amygdala reactivity and perceptual processing speed, both of which are altered in depression and aging. Amygdala reactivity was assessed using a face-matching BOLD fMRI paradigm in 365 Caucasian participants in the Duke Neurogenetics Study (DNS) (192 women, mean age 19.7 ± 1.2). Perceptual processing speed was indexed by reaction times in the same task and the Trail Making Test (TMT). The effect of rs7676614 on FREM3 mRNA brain expression levels was probed in a postmortem cohort of 169 Caucasian individuals (44 women, mean age 50.8 ± 14.9). The A allele of rs7676614 was associated with blunted amygdala reactivity to faces, slower reaction times in the face-matching condition (p < 0.04), as well as marginally slower performance on TMT Part B (p = 0.056). In the postmortem cohort, the T allele of rs6537170 (proxy for the rs7676614 A allele), was associated with trend-level reductions in gene expression in Brodmann areas 11 and 47 (p = 0.066), reminiscent of patterns characteristic of older age. The low-expressing allele of another FREM3 SNP (rs1391187) was similarly associated with reduced amygdala reactivity and slower TMT Part B speed, in addition to reduced BA47 activity and extraversion (p < 0.05). Together, these results suggest common genetic variation associated with reduced FREM3 expression may confer risk for a subtype of depression characterized by reduced reactivity to environmental stimuli and slower perceptual processing speed, possibly suggestive of

  13. Central Pain Processing in Early-Stage Parkinson's Disease: A Laser Pain fMRI Study

    PubMed Central

    Petschow, Christine; Scheef, Lukas; Paus, Sebastian; Zimmermann, Nadine; Schild, Hans H.; Klockgether, Thomas; Boecker, Henning

    2016-01-01

    Background & Objective Pain is a common non-motor symptom in Parkinson’s disease. As dopaminergic dysfunction is suggested to affect intrinsic nociceptive processing, this study was designed to characterize laser-induced pain processing in early-stage Parkinson’s disease patients in the dopaminergic OFF state, using a multimodal experimental approach at behavioral, autonomic, imaging levels. Methods 13 right-handed early-stage Parkinson’s disease patients without cognitive or sensory impairment were investigated OFF medication, along with 13 age-matched healthy control subjects. Measurements included warmth perception thresholds, heat pain thresholds, and central pain processing with event-related functional magnetic resonance imaging (erfMRI) during laser-induced pain stimulation at lower (E = 440 mJ) and higher (E = 640 mJ) target energies. Additionally, electrodermal activity was characterized during delivery of 60 randomized pain stimuli ranging from 440 mJ to 640 mJ, along with evaluation of subjective pain ratings on a visual analogue scale. Results No significant differences in warmth perception thresholds, heat pain thresholds, electrodermal activity and subjective pain ratings were found between Parkinson’s disease patients and controls, and erfMRI revealed a generally comparable activation pattern induced by laser-pain stimuli in brain areas belonging to the central pain matrix. However, relatively reduced deactivation was found in Parkinson’s disease patients in posterior regions of the default mode network, notably the precuneus and the posterior cingulate cortex. Conclusion Our data during pain processing extend previous findings suggesting default mode network dysfunction in Parkinson’s disease. On the other hand, they argue against a genuine pain-specific processing abnormality in early-stage Parkinson’s disease. Future studies are now required using similar multimodal experimental designs to examine pain processing in more advanced

  14. Perceptual decoupling or motor decoupling?

    PubMed

    Head, James; Helton, William S

    2013-09-01

    The current investigation was conducted to elucidate whether errors of commission in the Sustained Attention to Response Task (SART) are indicators of perceptual or motor decoupling. Twenty-eight participants completed SARTs with motor and perceptual aspects of the task manipulated. The participants completed four different SART blocks whereby stimuli location uncertainty and stimuli acquisition were manipulated. In previous studies of more traditional sustained attention tasks stimuli location uncertainty reduces sustained attention performance. In the case of the SART the motor manipulation (stimuli acquisition), but not the perceptual manipulation (stimuli location uncertainty) significantly reduced commission errors. The results suggest that the majority of SART commission errors are likely to be indicators of motor decoupling not necessarily perceptual decoupling.

  15. Simulative design and process optimization of the two-stage stretch-blow molding process

    SciTech Connect

    Hopmann, Ch.; Rasche, S.; Windeck, C.

    2015-05-22

    The total production costs of PET bottles are significantly affected by the costs of raw material. Approximately 70 % of the total costs are spent for the raw material. Therefore, stretch-blow molding industry intends to reduce the total production costs by an optimized material efficiency. However, there is often a trade-off between an optimized material efficiency and required product properties. Due to a multitude of complex boundary conditions, the design process of new stretch-blow molded products is still a challenging task and is often based on empirical knowledge. Application of current CAE-tools supports the design process by reducing development time and costs. This paper describes an approach to determine optimized preform geometry and corresponding process parameters iteratively. The wall thickness distribution and the local stretch ratios of the blown bottle are calculated in a three-dimensional process simulation. Thereby, the wall thickness distribution is correlated with an objective function and preform geometry as well as process parameters are varied by an optimization algorithm. Taking into account the correlation between material usage, process history and resulting product properties, integrative coupled simulation steps, e.g. structural analyses or barrier simulations, are performed. The approach is applied on a 0.5 liter PET bottle of Krones AG, Neutraubling, Germany. The investigations point out that the design process can be supported by applying this simulative optimization approach. In an optimization study the total bottle weight is reduced from 18.5 g to 15.5 g. The validation of the computed results is in progress.

  16. A Perceptual Repetition Blindness Effect

    NASA Technical Reports Server (NTRS)

    Hochhaus, Larry; Johnston, James C.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    Before concluding Repetition Blindness is a perceptual phenomenon, alternative explanations based on memory retrieval problems and report bias must be rejected. Memory problems were minimized by requiring a judgment about only a single briefly displayed field. Bias and sensitivity effects were empirically measured with an ROC-curve analysis method based on confidence ratings. Results from five experiments support the hypothesis that Repetition Blindness can be a perceptual phenomenon.

  17. Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions.

    PubMed

    Murphy, Gillian; Greene, Ciara M

    2016-01-01

    Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals. PMID:27625628

  18. Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions

    PubMed Central

    Murphy, Gillian; Greene, Ciara M.

    2016-01-01

    Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals. PMID:27625628

  19. Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions

    PubMed Central

    Murphy, Gillian; Greene, Ciara M.

    2016-01-01

    Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals.

  20. Industrial demonstration plant for the gasification of herb residue by fluidized bed two-stage process.

    PubMed

    Zeng, Xi; Shao, Ruyi; Wang, Fang; Dong, Pengwei; Yu, Jian; Xu, Guangwen

    2016-04-01

    A fluidized bed two-stage gasification process, consisting of a fluidized-bed (FB) pyrolyzer and a transport fluidized bed (TFB) gasifier, has been proposed to gasify biomass for fuel gas production with low tar content. On the basis of our previous fundamental study, an autothermal two-stage gasifier has been designed and built for gasify a kind of Chinese herb residue with a treating capacity of 600 kg/h. The testing data in the operational stable stage of the industrial demonstration plant showed that when keeping the reaction temperatures of pyrolyzer and gasifier respectively at about 700 °C and 850 °C, the heating value of fuel gas can reach 1200 kcal/Nm(3), and the tar content in the produced fuel gas was about 0.4 g/Nm(3). The results from this pilot industrial demonstration plant fully verified the feasibility and technical features of the proposed FB two-stage gasification process.

  1. Industrial demonstration plant for the gasification of herb residue by fluidized bed two-stage process.

    PubMed

    Zeng, Xi; Shao, Ruyi; Wang, Fang; Dong, Pengwei; Yu, Jian; Xu, Guangwen

    2016-04-01

    A fluidized bed two-stage gasification process, consisting of a fluidized-bed (FB) pyrolyzer and a transport fluidized bed (TFB) gasifier, has been proposed to gasify biomass for fuel gas production with low tar content. On the basis of our previous fundamental study, an autothermal two-stage gasifier has been designed and built for gasify a kind of Chinese herb residue with a treating capacity of 600 kg/h. The testing data in the operational stable stage of the industrial demonstration plant showed that when keeping the reaction temperatures of pyrolyzer and gasifier respectively at about 700 °C and 850 °C, the heating value of fuel gas can reach 1200 kcal/Nm(3), and the tar content in the produced fuel gas was about 0.4 g/Nm(3). The results from this pilot industrial demonstration plant fully verified the feasibility and technical features of the proposed FB two-stage gasification process. PMID:26849201

  2. Neural stages of spoken, written, and signed word processing in beginning second language learners

    PubMed Central

    Leonard, Matthew K.; Ferjan Ramirez, Naja; Torres, Christina; Hatrak, Marla; Mayberry, Rachel I.; Halgren, Eric

    2013-01-01

    We combined magnetoencephalography (MEG) and magnetic resonance imaging (MRI) to examine how sensory modality, language type, and language proficiency interact during two fundamental stages of word processing: (1) an early word encoding stage, and (2) a later supramodal lexico-semantic stage. Adult native English speakers who were learning American Sign Language (ASL) performed a semantic task for spoken and written English words, and ASL signs. During the early time window, written words evoked responses in left ventral occipitotemporal cortex, and spoken words in left superior temporal cortex. Signed words evoked activity in right intraparietal sulcus that was marginally greater than for written words. During the later time window, all three types of words showed significant activity in the classical left fronto-temporal language network, the first demonstration of such activity in individuals with so little second language (L2) instruction in sign. In addition, a dissociation between semantic congruity effects and overall MEG response magnitude for ASL responses suggested shallower and more effortful processing, presumably reflecting novice L2 learning. Consistent with previous research on non-dominant language processing in spoken languages, the L2 ASL learners also showed recruitment of right hemisphere and lateral occipital cortex. These results demonstrate that late lexico-semantic processing utilizes a common substrate, independent of modality, and that proficiency effects in sign language are comparable to those in spoken language. PMID:23847496

  3. Materials, Processes and Manufacturing in Ares 1 Upper Stage: Integration with Systems Design and Development

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.

    2008-01-01

    Ares I Crew Launch Vehicle Upper Stage is designed and developed based on sound systems engineering principles. Systems Engineering starts with Concept of Operations and Mission requirements, which in turn determine the launch system architecture and its performance requirements. The Ares I-Upper Stage is designed and developed to meet these requirements. Designers depend on the support from materials, processes and manufacturing during the design, development and verification of subsystems and components. The requirements relative to reliability, safety, operability and availability are also dependent on materials availability, characterization, process maturation and vendor support. This paper discusses the roles and responsibilities of materials and manufacturing engineering during the various phases of Ares IUS development, including design and analysis, hardware development, test and verification. Emphasis is placed how materials, processes and manufacturing support is integrated over the Upper Stage Project, both horizontally and vertically. In addition, the paper describes the approach used to ensure compliance with materials, processes, and manufacturing requirements during the project cycle, with focus on hardware systems design and development.

  4. A two-stage evolutionary process for designing TSK fuzzy rule-based systems.

    PubMed

    Cordon, O; Herrera, F

    1999-01-01

    Nowadays, fuzzy rule-based systems are successfully applied to many different real-world problems. Unfortunately, relatively few well-structured methodologies exist for designing and, in many cases, human experts are not able to express the knowledge needed to solve the problem in the form of fuzzy rules. Takagi-Sugeno-Kang (TSK) fuzzy rule-based systems were enunciated in order to solve this design problem because they are usually identified using numerical data. In this paper we present a two-stage evolutionary process for designing TSK fuzzy rule-based systems from examples combining a generation stage based on a (mu, lambda)-evolution strategy, in which the fuzzy rules with different consequents compete among themselves to form part of a preliminary knowledge base, and a refinement stage in which both the antecedent and consequent parts of the fuzzy rules in this previous knowledge base are adapted by a hybrid evolutionary process composed of a genetic algorithm and an evolution strategy to obtain the final Knowledge base whose rules cooperate in the best possible way. Some aspects make this process different from others proposed until now: the design problem is addressed in two different stages, the use of an angular coding of the consequent parameters that allows us to search across the whole space of possible solutions, and the use of the available knowledge about the system under identification to generate the initial populations of the Evolutionary Algorithms that causes the search process to obtain good solutions more quickly. The performance of the method proposed is shown by solving two different problems: the fuzzy modeling of some three-dimensional surfaces and the computing of the maintenance costs of electrical medium line in Spanish towns. Results obtained are compared with other kind of techniques, evolutionary learning processes to design TSK and Mamdani-type fuzzy rule-based systems in the first case, and classical regression and neural modeling

  5. Perceptually Lossless Wavelet Compression

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Yang, Gloria Y.; Solomon, Joshua A.; Villasenor, John

    1996-01-01

    The Discrete Wavelet Transform (DWT) decomposes an image into bands that vary in spatial frequency and orientation. It is widely used for image compression. Measures of the visibility of DWT quantization errors are required to achieve optimal compression. Uniform quantization of a single band of coefficients results in an artifact that is the sum of a lattice of random amplitude basis functions of the corresponding DWT synthesis filter, which we call DWT uniform quantization noise. We measured visual detection thresholds for samples of DWT uniform quantization noise in Y, Cb, and Cr color channels. The spatial frequency of a wavelet is r 2(exp -1), where r is display visual resolution in pixels/degree, and L is the wavelet level. Amplitude thresholds increase rapidly with spatial frequency. Thresholds also increase from Y to Cr to Cb, and with orientation from low-pass to horizontal/vertical to diagonal. We propose a mathematical model for DWT noise detection thresholds that is a function of level, orientation, and display visual resolution. This allows calculation of a 'perceptually lossless' quantization matrix for which all errors are in theory below the visual threshold. The model may also be used as the basis for adaptive quantization schemes.

  6. Perceptual aspects of singing.

    PubMed

    Sundberg, J

    1994-06-01

    The relations between acoustic and perceived characteristics of vowel sounds are demonstrated with respect to timbre, loudness, pitch, and expressive time patterns. The conditions for perceiving an ensemble of sine tones as one tone or several tones are reviewed. There are two aspects of timbre of voice sounds: vowel quality and voice quality. Although vowel quality depends mainly on the frequencies of the lowest two formants. In particular, the center frequency of the so-called singer's formant seems perceptually relevant. Vocal loudness, generally assumed to correspond closely to the sound pressure level, depends rather on the amplitude balance between the lower and the higher spectrum partials. The perceived pitch corresponds to the fundamental frequency, or for vibrato tones, the mean of this frequency. In rapid passages, such as coloratura singing, special patterns are used. Pitch and duration differences are categorically perceived in music. This means that small variations in tuning or duration do not affect the musical interval and the note value perceived. Categorical perception is used extensively in music performance for the purpose of musical expression because without violating the score, the singer may sharpen or flatten and lengthen or shorten the tones, thereby creating musical expression. PMID:8061767

  7. Four stage, fluidized bed gasification process minimizes NO{sub x}

    SciTech Connect

    Lewis, F.M.; Haug, R.T.

    1999-07-01

    In 1981, after a long and thorough study of alternative methods of sewage sludge (biosolids) disposal, the City of Los Angeles (CLA) embarked on a pilot test program to incinerate dried sewage sludge from its Hyperion Wastewater Treatment Plant. This dried sludge is typically 47% ash, 53% combustible, and has an average higher heating value (HHV), moisture, ash-free (MAF) of 10,675 Btu/Lbm. The dried sludge is called sludge derived fuel (SDF). Approximately 8% of the MAF fraction of SDF is fuel-bound nitrogen. When SDF, with its extremely high fuel-bound nitrogen, was combusted in conventional multiple hearth and fluidized bed pilot plant furnaces, NO{sub x} emissions were extremely high ({gt}1,000 ppm). Faced with this dilemma, the CLA initiated an R and D program to reduce NO{sub x}. The pilot tests with a sub-stoichiometric fluid bed and an excess air afterburner (two-stages) reduced NO{sub x} to 400--600 ppm. With one intermediate stage added (three-stage), NO{sub x} was reduced to 130--150 ppm. However, when the following four-stage process was developed and tested, NO{sub x} was reduced to 50--75 ppm. Stage 1: Sub-stoichiometric fluidized bed operating at a nominal 30% stoichiometric air (SA). Stage 2:Sub-stoichiometric zone operating at a nominal 80% SA. Stage 3: Stoichiometric zone operating at a nominal 100% SA. Stage 4: Excess air zone (Afterburner) operating at a nominal 135% SA (35% excess air). After pilot testing was complete and design parameters established, three full-size, fluid bed gasifiers (two operational--one standby) were designed, constructed and operated until 1996. This paper describes the design, operation, and emission testing of these four-stage fluid bed gasifiers with special emphasis on the problems of (a) pneumatic feeding of SDF powder into the pressurized bed and (b) baghouse fabrics (expanded PTEE membrane on PTFE scrim). Final emission test results for NO{sub x} and other criteria pollutants are also presented.

  8. HRI catalytic two-stage liquefaction (CTSL) process materials: chemical analysis and biological testing

    SciTech Connect

    Wright, C.W.; Later, D.W.

    1985-12-01

    This report presents data from the chemical analysis and biological testing of coal liquefaction materials obtained from the Hydrocarbon Research, Incorporated (HRI) catalytic two-stage liquefaction (CTSL) process. Materials from both an experimental run and a 25-day demonstration run were analyzed. Chemical methods of analysis included adsorption column chromatography, high-resolution gas chromatography, gas chromatography/mass spectrometry, low-voltage probe-inlet mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The biological activity was evaluated using the standard microbial mutagenicity assay and an initiation/promotion assay for mouse-skin tumorigenicity. Where applicable, the results obtained from the analyses of the CTSL materials have been compared to those obtained from the integrated and nonintegrated two-stage coal liquefaction processes. 18 refs., 26 figs., 22 tabs.

  9. Perceptually specific and perceptually non-specific influences on rereading benefits for spatially transformed text: evidence from eye movements.

    PubMed

    Sheridan, Heather; Reingold, Eyal M

    2012-12-01

    The present study used eye tracking methodology to examine rereading benefits for spatially transformed text. Eye movements were monitored while participants read the same target word twice, in two different low-constraint sentence frames. The congruency of perceptual processing was manipulated by either applying the same type of transformation to the word during the first and second presentations (i.e., the congruent condition), or employing two different types of transformations across the two presentations of the word (i.e., the incongruent condition). Perceptual specificity effects were demonstrated such that fixation times for the second presentation of the target word were shorter for the congruent condition compared to the incongruent condition. Moreover, we demonstrated an additional perceptually non-specific effect such that second reading fixation times were shorter for the incongruent condition relative to a baseline condition that employed a normal typography (i.e., non-transformed) during the first presentation and a transformation during the second presentation. Both of these effects (i.e., perceptually specific and perceptually non-specific) were similar in magnitude for high and low frequency words, and both effects persisted across a 1 week lag between the first and second readings. We discuss the present findings in the context of the distinction between conscious and unconscious memory, and the distinction between perceptually versus conceptually driven processing. PMID:23138157

  10. Similarity ratio analysis for early stage fault detection with optical emission spectrometer in plasma etching process.

    PubMed

    Yang, Jie; McArdle, Conor; Daniels, Stephen

    2014-01-01

    A Similarity Ratio Analysis (SRA) method is proposed for early-stage Fault Detection (FD) in plasma etching processes using real-time Optical Emission Spectrometer (OES) data as input. The SRA method can help to realise a highly precise control system by detecting abnormal etch-rate faults in real-time during an etching process. The method processes spectrum scans at successive time points and uses a windowing mechanism over the time series to alleviate problems with timing uncertainties due to process shift from one process run to another. A SRA library is first built to capture features of a healthy etching process. By comparing with the SRA library, a Similarity Ratio (SR) statistic is then calculated for each spectrum scan as the monitored process progresses. A fault detection mechanism, named 3-Warning-1-Alarm (3W1A), takes the SR values as inputs and triggers a system alarm when certain conditions are satisfied. This design reduces the chance of false alarm, and provides a reliable fault reporting service. The SRA method is demonstrated on a real semiconductor manufacturing dataset. The effectiveness of SRA-based fault detection is evaluated using a time-series SR test and also using a post-process SR test. The time-series SR provides an early-stage fault detection service, so less energy and materials will be wasted by faulty processing. The post-process SR provides a fault detection service with higher reliability than the time-series SR, but with fault testing conducted only after each process run completes. PMID:24755865

  11. Similarity ratio analysis for early stage fault detection with optical emission spectrometer in plasma etching process.

    PubMed

    Yang, Jie; McArdle, Conor; Daniels, Stephen

    2014-01-01

    A Similarity Ratio Analysis (SRA) method is proposed for early-stage Fault Detection (FD) in plasma etching processes using real-time Optical Emission Spectrometer (OES) data as input. The SRA method can help to realise a highly precise control system by detecting abnormal etch-rate faults in real-time during an etching process. The method processes spectrum scans at successive time points and uses a windowing mechanism over the time series to alleviate problems with timing uncertainties due to process shift from one process run to another. A SRA library is first built to capture features of a healthy etching process. By comparing with the SRA library, a Similarity Ratio (SR) statistic is then calculated for each spectrum scan as the monitored process progresses. A fault detection mechanism, named 3-Warning-1-Alarm (3W1A), takes the SR values as inputs and triggers a system alarm when certain conditions are satisfied. This design reduces the chance of false alarm, and provides a reliable fault reporting service. The SRA method is demonstrated on a real semiconductor manufacturing dataset. The effectiveness of SRA-based fault detection is evaluated using a time-series SR test and also using a post-process SR test. The time-series SR provides an early-stage fault detection service, so less energy and materials will be wasted by faulty processing. The post-process SR provides a fault detection service with higher reliability than the time-series SR, but with fault testing conducted only after each process run completes.

  12. Perceptual organization by proximity and similarity in schizophrenia.

    PubMed

    Kurylo, Daniel D; Pasternak, Roey; Silipo, Gail; Javitt, Daniel C; Butler, Pamela D

    2007-09-01

    Perceptual organization represents a basic and essential function that occurs at an intermediate level of visual processing. Much of the previous research on perceptual organization in schizophrenia employed indirect measurements, or included factors beyond sensory processing. The aims of the present study were to determine the integrity of perceptual organization in schizophrenia, as well as to determine the stimulus duration necessary to perform perceptual organization. Psychophysical measurements were compared between patients with schizophrenia and matched control subjects. Participants viewed dot patterns briefly presented on a computer monitor, and indicated whether stimuli appeared grouped as vertical or horizontal lines. Grouping was based upon either relative proximity or similarity in color. Across trials, relative proximity or color similarity was progressively reduced until stimuli became bi-stable (perceived as either of two patterns of grouping), establishing the grouping threshold. In separate conditions, stimuli were immediately followed by a mask to limit processing. Stimulus duration was progressively reduced until stimuli became bi-stable, establishing the critical stimulus duration (CSD). Schizophrenia patients demonstrated elevated grouping thresholds for grouping by proximity as well as color similarity. In addition, CSD was significantly extended for the schizophrenia group, with a nearly four-fold increase in duration of processing. These results provide direct evidence of impairment in schizophrenia for perceptual organization based upon spatial relationships and feature similarity, and suggest deficits in low-level perceptual organization processes. Although this study did not directly investigate the physiological correlates underlying perceptual impairments, these results are consistent with a theory of impaired lateral connections within visual cortical areas in schizophrenia. PMID:17681736

  13. Improvement in Visual Search with Practice: Mapping Learning-Related Changes in Neurocognitive Stages of Processing

    PubMed Central

    Clark, Kait; Appelbaum, L. Gregory; van den Berg, Berry; Mitroff, Stephen R.

    2015-01-01

    Practice can improve performance on visual search tasks; the neural mechanisms underlying such improvements, however, are not clear. Response time typically shortens with practice, but which components of the stimulus–response processing chain facilitate this behavioral change? Improved search performance could result from enhancements in various cognitive processing stages, including (1) sensory processing, (2) attentional allocation, (3) target discrimination, (4) motor-response preparation, and/or (5) response execution. We measured event-related potentials (ERPs) as human participants completed a five-day visual-search protocol in which they reported the orientation of a color popout target within an array of ellipses. We assessed changes in behavioral performance and in ERP components associated with various stages of processing. After practice, response time decreased in all participants (while accuracy remained consistent), and electrophysiological measures revealed modulation of several ERP components. First, amplitudes of the early sensory-evoked N1 component at 150 ms increased bilaterally, indicating enhanced visual sensory processing of the array. Second, the negative-polarity posterior–contralateral component (N2pc, 170–250 ms) was earlier and larger, demonstrating enhanced attentional orienting. Third, the amplitude of the sustained posterior contralateral negativity component (SPCN, 300–400 ms) decreased, indicating facilitated target discrimination. Finally, faster motor-response preparation and execution were observed after practice, as indicated by latency changes in both the stimulus-locked and response-locked lateralized readiness potentials (LRPs). These electrophysiological results delineate the functional plasticity in key mechanisms underlying visual search with high temporal resolution and illustrate how practice influences various cognitive and neural processing stages leading to enhanced behavioral performance. PMID:25834059

  14. Improvement in visual search with practice: mapping learning-related changes in neurocognitive stages of processing.

    PubMed

    Clark, Kait; Appelbaum, L Gregory; van den Berg, Berry; Mitroff, Stephen R; Woldorff, Marty G

    2015-04-01

    Practice can improve performance on visual search tasks; the neural mechanisms underlying such improvements, however, are not clear. Response time typically shortens with practice, but which components of the stimulus-response processing chain facilitate this behavioral change? Improved search performance could result from enhancements in various cognitive processing stages, including (1) sensory processing, (2) attentional allocation, (3) target discrimination, (4) motor-response preparation, and/or (5) response execution. We measured event-related potentials (ERPs) as human participants completed a five-day visual-search protocol in which they reported the orientation of a color popout target within an array of ellipses. We assessed changes in behavioral performance and in ERP components associated with various stages of processing. After practice, response time decreased in all participants (while accuracy remained consistent), and electrophysiological measures revealed modulation of several ERP components. First, amplitudes of the early sensory-evoked N1 component at 150 ms increased bilaterally, indicating enhanced visual sensory processing of the array. Second, the negative-polarity posterior-contralateral component (N2pc, 170-250 ms) was earlier and larger, demonstrating enhanced attentional orienting. Third, the amplitude of the sustained posterior contralateral negativity component (SPCN, 300-400 ms) decreased, indicating facilitated target discrimination. Finally, faster motor-response preparation and execution were observed after practice, as indicated by latency changes in both the stimulus-locked and response-locked lateralized readiness potentials (LRPs). These electrophysiological results delineate the functional plasticity in key mechanisms underlying visual search with high temporal resolution and illustrate how practice influences various cognitive and neural processing stages leading to enhanced behavioral performance.

  15. Perceptual discontinuities and categorization: Implications for speech perception

    NASA Astrophysics Data System (ADS)

    Holt, Lori L.; Lotto, Andrew J.; Diehl, Randy L.

    2003-04-01

    Behavioral experiments with infants, adults and nonhuman animals converge with neurophysiological findings to suggest that there is a discontinuity in auditory processing of stimulus components differing in onset time by about 20 ms. This discontinuity has been implicated as a basis for boundaries between speech categories distinguished by VOT. Here, we investigate how this discontinuity interacts with the learning of novel perceptual categories. Adult listeners were trained to categorize a nonspeech acoustic cue that mimics the temporal distinction of VOT. One group of listeners learned categories with a boundary coincident with the perceptual discontinuity. Another group learned categories defined such that the perceptual discontinuity fell within a category. Listeners in the latter group required significantly more experience to reach criterion categorization performance. The evidence of interactions between the perceptual discontinuity and the learned categories extended to generalization tests as well. It has been hypothesized that languages make use of perceptual discontinuities to promote perceptual distinctiveness among sounds within a language inventory. The present data suggest that these influences interact with category learning. As such, learnability may play a predictive role in selection of language sound inventories. Moreover, it may be possible to observe predictable learning effects in infant speech perception.

  16. A new taxonomy for perceptual filling-in

    PubMed Central

    Weil, Rimona S.; Rees, Geraint

    2011-01-01

    Perceptual filling-in occurs when structures of the visual system interpolate information across regions of visual space where that information is physically absent. It is a ubiquitous and heterogeneous phenomenon, which takes place in different forms almost every time we view the world around us, such as when objects are occluded by other objects or when they fall behind the blind spot. Yet, to date, there is no clear framework for relating these various forms of perceptual filling-in. Similarly, whether these and other forms of filling-in share common mechanisms is not yet known. Here we present a new taxonomy to categorize the different forms of perceptual filling-in. We then examine experimental evidence for the processes involved in each type of perceptual filling-in. Finally, we use established theories of general surface perception to show how contextualizing filling-in using this framework broadens our understanding of the possible shared mechanisms underlying perceptual filling-in. In particular, we consider the importance of the presence of boundaries in determining the phenomenal experience of perceptual filling-in. PMID:21059374

  17. Effects of drying process on the physicochemical properties of nopal cladodes at different maturity stages.

    PubMed

    Contreras-Padilla, Margarita; Gutiérrez-Cortez, Elsa; Valderrama-Bravo, María Del Carmen; Rojas-Molina, Isela; Espinosa-Arbeláez, Diego Germán; Suárez-Vargas, Raúl; Rodríguez-García, Mario Enrique

    2012-03-01

    Chemical proximate analysis was done in order to determine the changes of nutritional characteristics of nopal powders from three different maturity stages 50, 100, and 150 days and obtained by three different drying processes: freeze dried, forced air oven, and tunnel. Results indicate that nopal powder obtained by the process of freeze dried retains higher contents of protein, soluble fiber, and fat than the other two processes. Also, freeze dried process had less effect on color hue variable. No changes were observed in insoluble fiber content, chroma and lightness with the three different drying processes. Furthermore, the soluble fibers decreased with the age of nopal while insoluble fibers and ash content shows an opposite trend. In addition, the luminosity and hue values did not show differences among the maturity stages studied. The high content of dietary fibers of nopal pad powder could to be an interesting source of these important components for human diets and also could be used in food, cosmetics and pharmaceutical industry. PMID:22183868

  18. Stage 2 Process Performance Qualification (PPQ): a Scientific Approach to Determine the Number of PPQ Batches.

    PubMed

    Pazhayattil, Ajay; Alsmeyer, Daniel; Chen, Shu; Hye, Maksuda; Ingram, Marzena; Sanghvi, Pradeep

    2016-08-01

    The approach documented in this article reviews data from earlier process validation lifecycle stages with a described statistical model to provide the "best estimate" on the number of process performance qualification (PPQ) batches that should generate sufficient information to make a scientific and risk-based decision on product robustness. This approach is based upon estimation of a statistical confidence from the current product knowledge (Stage 1), historical variability for similar products/processes (batch-to-batch), and label claim specifications such as strength. The analysis is to determine the confidence level with the measurements of the product quality attributes and to compare them with the specifications. The projected minimum number of PPQ batches required will vary depending on the product, process understanding, and attributes, which are critical input parameters for the current statistical model. This new approach considers the critical finished product CQAs (assay, dissolution, and content uniformity), primarily because assay/content uniformity and dissolution as well as strength are the components of the label claim. The key CQAs determine the number of PPQ batches. This approach will ensure that sufficient scientific data is generated to demonstrate process robustness as desired by the 2011 FDA guidance.

  19. 4-rotor Desiccant Cooling Process Equipped with a Double Stage Dehumidification

    NASA Astrophysics Data System (ADS)

    Ando, Kosuke; Kodama, Akio; Okano, Hiroshi; Asada, Toshinobu

    2-rotor desiccant cooling process consisting of a honeycomb rotor dehumidifier and a sensible heat exchanger is a mainstream of the desiccant cooling process which are practically applied to supermarket, hospital and so on. However, this process cannot produce a sufficient dehumidifying performance in high humidity region. In this study, 4-rotor desiccant cooling process equipped with a double stage dehumidification was proposed and investigated experimentally. In this process, regeneration temperature around 60°C could produce a sufficient dehumidifying performance even at high ambient humidity. “Serial heat supply” mode was considered to improve the heat efficiency by the cascade use of regeneration heat inside the cooling cycle. The dehumidifying performance of the “serial heat supply” mode was only slightly lower than that of a “parallel heat supply” mode at which the same temperature hot air was supplied to the both heaters. However, dehumidifying performance of this “serial heat supply” mode was much higher than that of conventional 2-rotor desiccant cooling process. Furthermore, the desiccant rotors of 0.1m in thickness were mounted to 4-rotor desiccant cooling process in place of the 0.2m desiccant rotors. It was found that the drop of dehumidifying performance of the process equipped with 0.1m desiccant rotors was only by 10 percents comparing with the 0.2m rotor process. Moreover, it was found that optimization of rotation speed of the desiccant rotor was needed to improve the energy efficiency. Regarding the supply point of return air, it was also found that return air should be supplied to the regeneration inlet of the second stage for higher dehumidifying performance.

  20. A Mathematical Model for the Reduction Stage of the CAS-OB Process

    NASA Astrophysics Data System (ADS)

    Sulasalmi, Petri; Visuri, Ville-Valtteri; Kärnä, Aki; Järvinen, Mika; Ollila, Seppo; Fabritius, Timo

    2016-08-01

    This paper proposes a novel method for modeling the reduction stage of the CAS-OB process (composition adjustment by sealed argon bubbling-oxygen blowing). Our previous study proposed a model for the heating stage of the CAS-OB process; the purpose of the present study is to extend this work toward a more comprehensive model for the process in question. The CAS-OB process is designed for homogenization and control of the composition and temperature of steel. During the reduction stage, the steel phase is stirred intensely by employing the gas nozzles at the bottom of the ladle, which blow argon gas. It is assumed that the reduction rate of the top slag is dictated by the formation of slag droplets at the steel-slag interface. Slag droplets, which are generated due to turning of the steel flow in the spout, contribute mainly by increasing the interfacial area between the steel and slag phases. This phenomenon has been taken into account based on our previous study, in which the droplet size distribution and generation rate at different steel flow velocities. The reactions considered between the slag and steel phases are assumed to be mass transfer controlled and reversible. We validated the results from the model against the measurements from the real CAS-OB process. The results indicate that the model accurately predicts the end compositions of slag and steel. Moreover, it was discovered that the cooling rate of steel during the gas stirring given by the model is consistent with the results reported in the literature.

  1. Is the linguistic content of speech less salient than its perceptual features in autism?

    PubMed

    Järvinen-Pasley, Anna; Pasley, John; Heaton, Pamela

    2008-02-01

    Open-ended tasks are rarely used to investigate cognition in autism. No known studies have directly examined whether increased attention to the perceptual level of speech in autism might contribute to a reduced tendency to process language meaningfully. The present study investigated linguistic versus perceptual speech processing preferences. Children with autism and controls were tested on a quasi-open-format paradigm, in which speech stimuli contained competing linguistic and perceptual information, and could be processed at either level. Relative to controls, children with autism exhibited superior perceptual processing of speech. However, whilst their tendency to preferentially process linguistic rather than perceptual information was weaker than that of controls, it was nevertheless their primary processing mode. Implications for language acquisition in autism are discussed.

  2. Workload-Matched Adaptive Automation Support of Air Traffic Controller Information Processing Stages

    NASA Technical Reports Server (NTRS)

    Kaber, David B.; Prinzel, Lawrence J., III; Wright, Melanie C.; Clamann, Michael P.

    2002-01-01

    Adaptive automation (AA) has been explored as a solution to the problems associated with human-automation interaction in supervisory control environments. However, research has focused on the performance effects of dynamic control allocations of early stage sensory and information acquisition functions. The present research compares the effects of AA to the entire range of information processing stages of human operators, such as air traffic controllers. The results provide evidence that the effectiveness of AA is dependent on the stage of task performance (human-machine system information processing) that is flexibly automated. The results suggest that humans are better able to adapt to AA when applied to lower-level sensory and psychomotor functions, such as information acquisition and action implementation, as compared to AA applied to cognitive (analysis and decision-making) tasks. The results also provide support for the use of AA, as compared to completely manual control. These results are discussed in terms of implications for AA design for aviation.

  3. Performance Evaluation of Staged Bosch Process for CO2 Reduction to Produce Life Support Consumables

    NASA Technical Reports Server (NTRS)

    Vilekar, Saurabh A.; Hawley, Kyle; Junaedi, Christian; Walsh, Dennis; Roychoudhury, Subir; Abney. Morgan B.; Mansell, James M.

    2012-01-01

    Utilizing carbon dioxide to produce water and hence oxygen is critical for sustained manned missions in space, and to support both NASA's cabin Atmosphere Revitalization System (ARS) and In-Situ Resource Utilization (ISRU) concepts. For long term missions beyond low Earth orbit, where resupply is significantly more difficult and costly, open loop ARS, like Sabatier, consume inputs such as hydrogen. The Bosch process, on the other hand, has the potential to achieve complete loop closure and is hence a preferred choice. However, current single stage Bosch reactor designs suffer from a large recycle penalty due to slow reaction rates and the inherent limitation in approaching thermodynamic equilibrium. Developmental efforts are seeking to improve upon the efficiency (hence reducing the recycle penalty) of current single stage Bosch reactors which employ traditional steel wool catalysts. Precision Combustion, Inc. (PCI), with support from NASA, has investigated the potential for utilizing catalysts supported over short-contact time Microlith substrates for the Bosch reaction to achieve faster reaction rates, higher conversions, and a reduced recycle flows. Proof-of-concept testing was accomplished for a staged Bosch process by splitting the chemistry in two separate reactors, first being the reverse water-gas-shift (RWGS) and the second being the carbon formation reactor (CFR) via hydrogenation and/or Boudouard. This paper presents the results from this feasibility study at various operating conditions. Additionally, results from two 70 hour durability tests for the RWGS reactor are discussed.

  4. Heavy metals and its chemical speciation in sewage sludge at different stages of processing.

    PubMed

    Tytła, Malwina; Widziewicz, Kamila; Zielewicz, Ewa

    2016-01-01

    The analysis of heavy metal concentrations and forms in sewage sludge constitutes an important issue in terms of both health and environmental hazards the metals pose. The total heavy metals concentration enables only the assessment of its contamination. Hence the knowledge of chemical forms is required to determine their environmental mobility and sludge final disposal. Heavy metals speciation was studied by using four-stage sequential extraction BCR (Community Bureau of Reference). This study was aimed at determining the total concentration of selected heavy metals (Zn, Cu, Ni, Pb, Cd, Cr and Hg) and their chemical forms (except for Hg) in sludge collected at different stages of its processing at two municipal Wastewater Treatment Plants in southern Poland. Metals contents in sludge samples were determined by using flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). This study shows that Zn and Cu appeared to be the most abundant in sludge, while Cd and Hg were in the lowest concentrations. The sewage sludge revealed the domination of immobile fractions over the mobile ones. The oxidizable and residual forms were dominant for all the heavy metals. There was also a significant difference in metals speciation between sludges of different origin which was probably due to differences in wastewater composition and processes occurring in biological stage of wastewater treatment. The results indicate a negligible capability of metals to migrate from sludge into the environment. Our research revealed a significant impact of thickening, stabilization and hygienization on the distribution of heavy metals in sludge and their mobility.

  5. Issues in Perceptual Speech Analysis in Cleft Palate and Related Disorders: A Review

    ERIC Educational Resources Information Center

    Sell, Debbie

    2005-01-01

    Perceptual speech assessment is central to the evaluation of speech outcomes associated with cleft palate and velopharyngeal dysfunction. However, the complexity of this process is perhaps sometimes underestimated. To draw together the many different strands in the complex process of perceptual speech assessment and analysis, and make…

  6. Reward modulates the effect of visual cortical microstimulation on perceptual decisions.

    PubMed

    Cicmil, Nela; Cumming, Bruce G; Parker, Andrew J; Krug, Kristine

    2015-01-01

    Effective perceptual decisions rely upon combining sensory information with knowledge of the rewards available for different choices. However, it is not known where reward signals interact with the multiple stages of the perceptual decision-making pathway and by what mechanisms this may occur. We combined electrical microstimulation of functionally specific groups of neurons in visual area V5/MT with performance-contingent reward manipulation, while monkeys performed a visual discrimination task. Microstimulation was less effective in shifting perceptual choices towards the stimulus preferences of the stimulated neurons when available reward was larger. Psychophysical control experiments showed this result was not explained by a selective change in response strategy on microstimulated trials. A bounded accumulation decision model, applied to analyse behavioural performance, revealed that the interaction of expected reward with microstimulation can be explained if expected reward modulates a sensory representation stage of perceptual decision-making, in addition to the better-known effects at the integration stage. PMID:26402458

  7. Altered perceptual binding in Gilles de la Tourette syndrome.

    PubMed

    Beste, Christian; Tübing, Jennifer; Seeliger, Helen; Bäumer, Tobias; Brandt, Valerie; Stock, Ann-Kathrin; Münchau, Alexander

    2016-10-01

    Gilles de la Tourette syndrome (GTS) is a common multifaceted neuropsychiatric disorder. Research in GTS has traditionally focussed on mechanisms underlying changes in motor processes in these patients. There is, however, growing interest in GTS related sensory phenomena. According to the Theory of Event-coding (TEC), sensory stimuli do not only serve representational functions but also action-related functions. In the current study, we use the TEC framework to examine whether the way perceptual features are processed is altered in GTS. The results show that basic perceptual processes differ between GTS patients and healthy controls which might be central for the understanding of this disorder. Details or features of perceptual objects were less bound in GTS suggesting that perceptual features integration is attenuated in them. Behavioural findings were unrelated to patient characteristics implying that they might represent trait abnormalities. It is possible that altered perceptual processing in GTS is due to a long-range under-connectivity of parietal areas with other brain regions repeatedly been described in these patients.

  8. Altered perceptual binding in Gilles de la Tourette syndrome.

    PubMed

    Beste, Christian; Tübing, Jennifer; Seeliger, Helen; Bäumer, Tobias; Brandt, Valerie; Stock, Ann-Kathrin; Münchau, Alexander

    2016-10-01

    Gilles de la Tourette syndrome (GTS) is a common multifaceted neuropsychiatric disorder. Research in GTS has traditionally focussed on mechanisms underlying changes in motor processes in these patients. There is, however, growing interest in GTS related sensory phenomena. According to the Theory of Event-coding (TEC), sensory stimuli do not only serve representational functions but also action-related functions. In the current study, we use the TEC framework to examine whether the way perceptual features are processed is altered in GTS. The results show that basic perceptual processes differ between GTS patients and healthy controls which might be central for the understanding of this disorder. Details or features of perceptual objects were less bound in GTS suggesting that perceptual features integration is attenuated in them. Behavioural findings were unrelated to patient characteristics implying that they might represent trait abnormalities. It is possible that altered perceptual processing in GTS is due to a long-range under-connectivity of parietal areas with other brain regions repeatedly been described in these patients. PMID:27544346

  9. Early Experience and Visual Information Processing in Perceptual and Reading Disorders; Proceedings of a Conference Held October 27-30, 1968, at Lake Mohonk, New York, in Association with the Committee on Brain Sciences, Div. of Medical Sciences, National Research Council.

    ERIC Educational Resources Information Center

    Young, Francis A., Ed.; Lindsley, Donald B., Ed.

    This book brings together papers presented at a conference on early experience and visual information processing in perceptual and reading disorders sponsored by the National Academy of Sciences. The goal of the conference was to integrate basic knowledge of structure and mechanisms of eye and brain with their function and their behavioral roles…

  10. Development of a Two-Stage Microalgae Dewatering Process - A Life Cycle Assessment Approach.

    PubMed

    Soomro, Rizwan R; Ndikubwimana, Theoneste; Zeng, Xianhai; Lu, Yinghua; Lin, Lu; Danquah, Michael K

    2016-01-01

    Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented.

  11. Early-Stage Capital Cost Estimation of Biorefinery Processes: A Comparative Study of Heuristic Techniques.

    PubMed

    Tsagkari, Mirela; Couturier, Jean-Luc; Kokossis, Antonis; Dubois, Jean-Luc

    2016-09-01

    Biorefineries offer a promising alternative to fossil-based processing industries and have undergone rapid development in recent years. Limited financial resources and stringent company budgets necessitate quick capital estimation of pioneering biorefinery projects at the early stages of their conception to screen process alternatives, decide on project viability, and allocate resources to the most promising cases. Biorefineries are capital-intensive projects that involve state-of-the-art technologies for which there is no prior experience or sufficient historical data. This work reviews existing rapid cost estimation practices, which can be used by researchers with no previous cost estimating experience. It also comprises a comparative study of six cost methods on three well-documented biorefinery processes to evaluate their accuracy and precision. The results illustrate discrepancies among the methods because their extrapolation on biorefinery data often violates inherent assumptions. This study recommends the most appropriate rapid cost methods and urges the development of an improved early-stage capital cost estimation tool suitable for biorefinery processes.

  12. Early-Stage Capital Cost Estimation of Biorefinery Processes: A Comparative Study of Heuristic Techniques.

    PubMed

    Tsagkari, Mirela; Couturier, Jean-Luc; Kokossis, Antonis; Dubois, Jean-Luc

    2016-09-01

    Biorefineries offer a promising alternative to fossil-based processing industries and have undergone rapid development in recent years. Limited financial resources and stringent company budgets necessitate quick capital estimation of pioneering biorefinery projects at the early stages of their conception to screen process alternatives, decide on project viability, and allocate resources to the most promising cases. Biorefineries are capital-intensive projects that involve state-of-the-art technologies for which there is no prior experience or sufficient historical data. This work reviews existing rapid cost estimation practices, which can be used by researchers with no previous cost estimating experience. It also comprises a comparative study of six cost methods on three well-documented biorefinery processes to evaluate their accuracy and precision. The results illustrate discrepancies among the methods because their extrapolation on biorefinery data often violates inherent assumptions. This study recommends the most appropriate rapid cost methods and urges the development of an improved early-stage capital cost estimation tool suitable for biorefinery processes. PMID:27484398

  13. Development of a Two-Stage Microalgae Dewatering Process - A Life Cycle Assessment Approach.

    PubMed

    Soomro, Rizwan R; Ndikubwimana, Theoneste; Zeng, Xianhai; Lu, Yinghua; Lin, Lu; Danquah, Michael K

    2016-01-01

    Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented. PMID:26904075

  14. Performance of an innovative two-stage process converting food waste to hydrogen and methane.

    PubMed

    Han, Sun-Kee; Shin, Hang-Sik

    2004-02-01

    This study was conducted to evaluate the performance of an innovative two-stage process, BIOCELL, that was developed to produce hydrogen (H2) and methane (CH4) from food waste on the basis of phase separation, reactor rotation mode, and sequential batch technique. The BIOCELL process consisted of four leaching-bed reactors for H2 recovery and post-treatment and a UASB reactor for CH4 recovery. The leaching-bed reactors were operated in a rotation mode with a 2-day interval between degradation stages. The sequential batch technique was useful to optimize environmental conditions during H2 fermentation. The BIOCELL process demonstrated that, at the high volatile solids (VS) loading rate of 11.9 kg/m3 x day, it could remove 72.5% of VS and convert VS(removed) to H2 (28.2%) and CH4 (69.9%) on a chemical oxygen demand (COD) basis in 8 days. H2 gas production rate was 3.63 m3/m3 x day, while CH4 gas production rate was 1.75 m3/m3 x day. The yield values of H2 and CH4 were 0.31 and 0.21 m3/kg VS(added), respectively. Moreover, the output from the post-treatment could be used as a soil amendment. The BIOCELL process proved to be stable, reliable, and effective in resource recovery as well as waste stabilization.

  15. Development of a Two-Stage Microalgae Dewatering Process – A Life Cycle Assessment Approach

    PubMed Central

    Soomro, Rizwan R.; Zeng, Xianhai; Lu, Yinghua; Lin, Lu; Danquah, Michael K.

    2016-01-01

    Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented. PMID:26904075

  16. Exploration into Stages in the Information Search Process in Online Information Retrieval: Communication between Users and Intermediaries.

    ERIC Educational Resources Information Center

    Kuhlthau, Carol; And Others

    1992-01-01

    Describes a study that examined interactions between users and intermediaries prior to online searching to examine communication about the user's stage in the search process. A model of information seeking that views the information search process as a series of cognitive stages is presented, and implications for user-intermediary interactions are…

  17. Perceptual organization in computer vision - A review and a proposal for a classificatory structure

    NASA Technical Reports Server (NTRS)

    Sarkar, Sudeep; Boyer, Kim L.

    1993-01-01

    The evolution of perceptual organization in biological vision, and its necessity in advanced computer vision systems, arises from the characteristic that perception, the extraction of meaning from sensory input, is an intelligent process. This is particularly so for high order organisms and, analogically, for more sophisticated computational models. The role of perceptual organization in computer vision systems is explored. This is done from four vantage points. First, a brief history of perceptual organization research in both humans and computer vision is offered. Next, a classificatory structure in which to cast perceptual organization research to clarify both the nomenclature and the relationships among the many contributions is proposed. Thirdly, the perceptual organization work in computer vision in the context of this classificatory structure is reviewed. Finally, the array of computational techniques applied to perceptual organization problems in computer vision is surveyed.

  18. Tracking the changing features of multiple objects: progressively poorer perceptual precision and progressively greater perceptual lag.

    PubMed

    Howard, Christina J; Holcombe, Alex O

    2008-04-01

    To measure the limits on attentive tracking of continuously changing features, in our task objects constantly changed smoothly and unpredictably in orientation, spatial period or position. Observers reported the last state of one of the objects. We observed a gradual decline in performance as the number of tracked objects increased, implicating a graded processing resource. Additionally, responses were more similar to previous states of the tracked object than its final state, especially in the case of spatial frequency. Indeed for spatial frequency, this perceptual lag reached 250ms when tracking four objects. The pattern of the perceptual lags, the graded effect of set size, and the double-report performance suggest the presence of both serial and parallel processing elements.

  19. Modeling of the last stage of production phase of oxytetracycline fermentation processes.

    PubMed

    Xu, C; Fang, C; Ma, Z

    1993-01-01

    In an attempt to disclose the reason why, during the last stage of FBOFP (fed-batch oxytetracycline fermentation processes) its specific production rate in general decreases notably, the authors started with the modeling of the process based on operation data, and thus reached the conclusion that this is due to too low residual nitrogen in the substrate. This inference is quite unacceptable to the current practice of the process operations. It was finally realized that the trouble lies in that our old measurement method of residual nitrogen is misleading. Upon using improved measuring method, it was found that while the total residual nitrogen is plentiful, the available nitrogen notably decreases with time, and thus confirmed the authors' conclusions. Experiments on industrial fermentators showed that the product can be increased by 1%, and the titer reaches 3200 micrograms/ml.

  20. Transfer of perceptual-motor training and the space adaptation syndrome

    NASA Technical Reports Server (NTRS)

    Kennedy, R. S.; Berbaum, K. S.; Williams, M. C.; Brannan, J.; Welch, R. B.

    1987-01-01

    Perceptual cue conflict may be the basis for the symptoms which are experienced by space travelers in microgravity conditions. Recovery has been suggested to take place after perceptual modification or reinterpretation. To elucidate this process, 10 subjects who repeatedly experienced a visual/vestibular conflict over trials and days, were tested in a similar but not identical perceptual situation (pseudo-Coriolis) to determine whether any savings in perceptual adaptation had occurred as compared to an unpracticed control group (N = 40). The practiced subjects experienced lessening dizziness and ataxia within and over sessions.

  1. Perceptual Biases in Relation to Paranormal and Conspiracy Beliefs.

    PubMed

    van Elk, Michiel

    2015-01-01

    Previous studies have shown that one's prior beliefs have a strong effect on perceptual decision-making and attentional processing. The present study extends these findings by investigating how individual differences in paranormal and conspiracy beliefs are related to perceptual and attentional biases. Two field studies were conducted in which visitors of a paranormal conducted a perceptual decision making task (i.e. the face/house categorization task; Experiment 1) or a visual attention task (i.e. the global/local processing task; Experiment 2). In the first experiment it was found that skeptics compared to believers more often incorrectly categorized ambiguous face stimuli as representing a house, indicating that disbelief rather than belief in the paranormal is driving the bias observed for the categorization of ambiguous stimuli. In the second experiment, it was found that skeptics showed a classical 'global-to-local' interference effect, whereas believers in conspiracy theories were characterized by a stronger 'local-to-global interference effect'. The present study shows that individual differences in paranormal and conspiracy beliefs are associated with perceptual and attentional biases, thereby extending the growing body of work in this field indicating effects of cultural learning on basic perceptual processes. PMID:26114604

  2. Perceptual Biases in Relation to Paranormal and Conspiracy Beliefs

    PubMed Central

    van Elk, Michiel

    2015-01-01

    Previous studies have shown that one’s prior beliefs have a strong effect on perceptual decision-making and attentional processing. The present study extends these findings by investigating how individual differences in paranormal and conspiracy beliefs are related to perceptual and attentional biases. Two field studies were conducted in which visitors of a paranormal conducted a perceptual decision making task (i.e. the face / house categorization task; Experiment 1) or a visual attention task (i.e. the global / local processing task; Experiment 2). In the first experiment it was found that skeptics compared to believers more often incorrectly categorized ambiguous face stimuli as representing a house, indicating that disbelief rather than belief in the paranormal is driving the bias observed for the categorization of ambiguous stimuli. In the second experiment, it was found that skeptics showed a classical ‘global-to-local’ interference effect, whereas believers in conspiracy theories were characterized by a stronger ‘local-to-global interference effect’. The present study shows that individual differences in paranormal and conspiracy beliefs are associated with perceptual and attentional biases, thereby extending the growing body of work in this field indicating effects of cultural learning on basic perceptual processes. PMID:26114604

  3. Bayesian natural selection and the evolution of perceptual systems.

    PubMed Central

    Geisler, Wilson S; Diehl, Randy L

    2002-01-01

    In recent years, there has been much interest in characterizing statistical properties of natural stimuli in order to better understand the design of perceptual systems. A fruitful approach has been to compare the processing of natural stimuli in real perceptual systems with that of ideal observers derived within the framework of Bayesian statistical decision theory. While this form of optimization theory has provided a deeper understanding of the information contained in natural stimuli as well as of the computational principles employed in perceptual systems, it does not directly consider the process of natural selection, which is ultimately responsible for design. Here we propose a formal framework for analysing how the statistics of natural stimuli and the process of natural selection interact to determine the design of perceptual systems. The framework consists of two complementary components. The first is a maximum fitness ideal observer, a standard Bayesian ideal observer with a utility function appropriate for natural selection. The second component is a formal version of natural selection based upon Bayesian statistical decision theory. Maximum fitness ideal observers and Bayesian natural selection are demonstrated in several examples. We suggest that the Bayesian approach is appropriate not only for the study of perceptual systems but also for the study of many other systems in biology. PMID:12028784

  4. Confocal XANES and the Attic black glaze: the three-stage firing process through modern reproduction.

    PubMed

    Lühl, Lars; Hesse, Bernhard; Mantouvalou, Ioanna; Wilke, Max; Mahlkow, Sammia; Aloupi-Siotis, Eleni; Kanngiesser, Birgit

    2014-07-15

    The decorated black- and red-figured Athenian vases (sixth and fifth century BC) and the plain black-glazed ware represent a milestone in our material culture due to their aesthetic and technological value; the Attic black glaze is of particular interest since it is a highly resistant potash-alumino-silicate glass, colored by magnetite nanocrystals (<200 nm). This study presents a new methodological approach for correlating the iron oxidation state in the black glaze layer with the manufacturing process by means of conventional and confocal X-ray absorption near edge spectroscopy (XANES). The enhanced surface sensitivity of confocal XANES is combined with conventional XANES resulting in higher counting rates to reliably evaluate the iron oxidation state (Fe(3+)/ΣFe) of the surface layer. A detailed description of the new evaluation procedure is presented. The three-stage firing process was retraced by correlating selected attic black-glazed (BG) specimens from different periods (Archaic, Classical, Hellenistic) with laboratory reproductions. The modern BG specimens serving as reference samples were produced by following the three-stage firing process (i.e., under oxidizing-reducing-oxidizing (ORO) conditions) at different top temperatures, using clay suspensions of different particle size produced with treatment of raw illitic clays from Attica. PMID:24905420

  5. Formation of CuInSSe thin films by conventional two-stage process

    NASA Astrophysics Data System (ADS)

    Shrotriya, Vipin; Rajaram, P.

    2016-05-01

    We have fabricated Crystalline CuInSSe thin films on glass substrate by conventional two-stage process. In first stage CuInS2 thin films have been grown on glass substrate by spray pyrolysis method at constant temperature 320°C. The CuCl2, InCl3, and thiourea were used as source materials for the Cu, In, and S precursors respectively and the Cu/In ratio is kept at 1.0. In second stage the precursor films of CuInS2 are selenized to get CuInSSe. The grown thin films of CuInS2 and CuInSSe were characterized by XRD, SEM and optical studies. The average crystallite size of the CISS thin films is found to be in the range 10-20 nm, using the Scherrer formula. The band gap value of the CuInSSe films is found to be 1.26 eV.

  6. Quantitation of trans-aconitic acid in different stages of the sugar-manufacturing process.

    PubMed

    Montoya, Guillermo; Londono, July; Cortes, Paola; Izquierdo, Olga

    2014-08-20

    The sugar cane industry has seen how biomass production in sugar mills would be converted to a readily available source of molecules besides sugar. Properly managed, byproducts would be transformed into a sustainable source of renewable and environmentally friendly chemical products. As a principal and more abundant organic acid in sugar cane juice, trans-aconitic acid (TAA) has been studied for use as a plasticizer in the polymer industry. However, up to now no industrial-scale application has been reported. As a reasonable approach to recover TAA from a sugar mill, first, an analytical method to determine its presence in all stages of the sugar-manufacturing process is needed. A new modern method was developed to measure TAA in seven stages in a sugar mill located in Valle del Cauca, Colombia. The stages with higher content of TAA were syrup, with 3363.6 ± 589.3 mg/L, and honey (molasses), with 6110.05 ± 139.5 mg/L. PMID:25098840

  7. Quantitation of trans-aconitic acid in different stages of the sugar-manufacturing process.

    PubMed

    Montoya, Guillermo; Londono, July; Cortes, Paola; Izquierdo, Olga

    2014-08-20

    The sugar cane industry has seen how biomass production in sugar mills would be converted to a readily available source of molecules besides sugar. Properly managed, byproducts would be transformed into a sustainable source of renewable and environmentally friendly chemical products. As a principal and more abundant organic acid in sugar cane juice, trans-aconitic acid (TAA) has been studied for use as a plasticizer in the polymer industry. However, up to now no industrial-scale application has been reported. As a reasonable approach to recover TAA from a sugar mill, first, an analytical method to determine its presence in all stages of the sugar-manufacturing process is needed. A new modern method was developed to measure TAA in seven stages in a sugar mill located in Valle del Cauca, Colombia. The stages with higher content of TAA were syrup, with 3363.6 ± 589.3 mg/L, and honey (molasses), with 6110.05 ± 139.5 mg/L.

  8. Perceptual hysteresis as a marker of perceptual inflexibility in schizophrenia.

    PubMed

    Martin, Jean-Rémy; Dezecache, Guillaume; Pressnitzer, Daniel; Nuss, Philippe; Dokic, Jérôme; Bruno, Nicolas; Pacherie, Elisabeth; Franck, Nicolas

    2014-11-01

    People with schizophrenia are known to exhibit difficulties in the updating of their current belief states even in the light of disconfirmatory evidence. In the present study we tested the hypothesis that people with schizophrenia could also manifest perceptual inflexibility, or difficulties in the updating of their current sensory states. The presence of perceptual inflexibility might contribute both to the patients' altered perception of reality and the formation of some delusions as well as to their social cognition deficits. Here, we addressed this issue with a protocol of auditory hysteresis, a direct measure of sensory persistence, on a population of stabilized antipsychotic-treated schizophrenia patients and a sample of control subjects. Trials consisted of emotional signals (i.e., screams) and neutral signals (i.e., spectrally-rotated versions of the emotional stimuli) progressively emerging from white noise - Ascending Sequences - or progressively fading away in white noise - Descending Sequences. Results showed that patients presented significantly stronger hysteresis effects than control subjects, as evidenced by a higher rate of perceptual reports in Descending Sequences. The present study thus provides direct evidence of perceptual inflexibility in schizophrenia. PMID:25147080

  9. Sharpened cortical tuning and enhanced cortico-cortical communication contribute to the long-term neural mechanisms of visual motion perceptual learning.

    PubMed

    Chen, Nihong; Bi, Taiyong; Zhou, Tiangang; Li, Sheng; Liu, Zili; Fang, Fang

    2015-07-15

    Much has been debated about whether the neural plasticity mediating perceptual learning takes place at the sensory or decision-making stage in the brain. To investigate this, we trained human subjects in a visual motion direction discrimination task. Behavioral performance and BOLD signals were measured before, immediately after, and two weeks after training. Parallel to subjects' long-lasting behavioral improvement, the neural selectivity in V3A and the effective connectivity from V3A to IPS (intraparietal sulcus, a motion decision-making area) exhibited a persistent increase for the trained direction. Moreover, the improvement was well explained by a linear combination of the selectivity and connectivity increases. These findings suggest that the long-term neural mechanisms of motion perceptual learning are implemented by sharpening cortical tuning to trained stimuli at the sensory processing stage, as well as by optimizing the connections between sensory and decision-making areas in the brain.

  10. Perceptual interference decays over short unfilled intervals.

    PubMed

    Schulkind, M D

    2000-09-01

    The perceptual interference effect refers to the fact that object identification is directly related to the amount of information available at initial exposure. The present article investigated whether perceptual interference would dissipate when a short, unfilled interval was introduced between exposures to a degraded object. Across three experiments using both musical and pictorial stimuli, identification performance increased directly with the length of the unfilled interval. Consequently, significant perceptual interference was obtained only when the interval between exposures was relatively short (< 500 msec for melodies; < 300 msec for pictures). These results are consistent with explanations that attribute perceptual interference to increased perceptual noise created by exposures to highly degraded objects. The data also suggest that perceptual interference is mediated by systems that are not consciously controlled by the subject and that perceptual interference in the visual domain decays more rapidly than perceptual interference in the auditory domain. PMID:11105520

  11. Functional Hemispheric Asymmetries of Global/Local Processing Mirrored by the Steady-State Visual Evoked Potential

    ERIC Educational Resources Information Center

    Martens, Ulla; Hubner, Ronald

    2013-01-01

    While hemispheric differences in global/local processing have been reported by various studies, it is still under dispute at which processing stage they occur. Primarily, it was assumed that these asymmetries originate from an early perceptual stage. Instead, the content-level binding theory (Hubner & Volberg, 2005) suggests that the hemispheres…

  12. Parallel processing of general and specific threat during early stages of perception.

    PubMed

    You, Yuqi; Li, Wen

    2016-03-01

    Differential processing of threat can consummate as early as 100 ms post-stimulus. Moreover, early perception not only differentiates threat from non-threat stimuli but also distinguishes among discrete threat subtypes (e.g. fear, disgust and anger). Combining spatial-frequency-filtered images of fear, disgust and neutral scenes with high-density event-related potentials and intracranial source estimation, we investigated the neural underpinnings of general and specific threat processing in early stages of perception. Conveyed in low spatial frequencies, fear and disgust images evoked convergent visual responses with similarly enhanced N1 potentials and dorsal visual (middle temporal gyrus) cortical activity (relative to neutral cues; peaking at 156 ms). Nevertheless, conveyed in high spatial frequencies, fear and disgust elicited divergent visual responses, with fear enhancing and disgust suppressing P1 potentials and ventral visual (occipital fusiform) cortical activity (peaking at 121 ms). Therefore, general and specific threat processing operates in parallel in early perception, with the ventral visual pathway engaged in specific processing of discrete threats and the dorsal visual pathway in general threat processing. Furthermore, selectively tuned to distinctive spatial-frequency channels and visual pathways, these parallel processes underpin dimensional and categorical threat characterization, promoting efficient threat response. These findings thus lend support to hybrid models of emotion.

  13. Political Disenchantment: A Cognitive-Perceptual Theory of Political Alienation.

    ERIC Educational Resources Information Center

    Long, Samuel

    An investigation of a cognitive-perceptual model to measure adolescents' feelings of political alienation is reported. The model hypothesizes that fundamental to the political alienation process is a feared actual or potential loss of freedom; this process is called psychological reactance. The sample consisted of 460 senior high school students…

  14. A Theory of Perceptual Learning: Uncertainty Reduction and Reading.

    ERIC Educational Resources Information Center

    Henk, William A.

    Behaviorism cannot adequately explain language processing. A synthesis of the psycholinguistic and information processing approaches of cognitive psychology, however, can provide the basis for a speculative analysis of reading, if this synthesis is tempered by a perceptual learning theory of uncertainty reduction. Theorists of information…

  15. The Neural Basis of Perceptual Category Learning in Human Infants

    ERIC Educational Resources Information Center

    Grossmann, Tobias; Gliga, Teodora; Johnson, Mark H.; Mareschal, Denis

    2009-01-01

    We measured looking times and ERPs to examine the cognitive and brain bases of perceptual category learning in 6-month-old infants. In Experiment 1, we showed that categorization and exemplar discrimination rely on different cortical processes. Specifically, the repetition of individual exemplars resulted in differential cortical processing at…

  16. Perceptual Image Compression in Telemedicine

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Ahumada, Albert J., Jr.; Eckstein, Miguel; Null, Cynthia H. (Technical Monitor)

    1996-01-01

    The next era of space exploration, especially the "Mission to Planet Earth" will generate immense quantities of image data. For example, the Earth Observing System (EOS) is expected to generate in excess of one terabyte/day. NASA confronts a major technical challenge in managing this great flow of imagery: in collection, pre-processing, transmission to earth, archiving, and distribution to scientists at remote locations. Expected requirements in most of these areas clearly exceed current technology. Part of the solution to this problem lies in efficient image compression techniques. For much of this imagery, the ultimate consumer is the human eye. In this case image compression should be designed to match the visual capacities of the human observer. We have developed three techniques for optimizing image compression for the human viewer. The first consists of a formula, developed jointly with IBM and based on psychophysical measurements, that computes a DCT quantization matrix for any specified combination of viewing distance, display resolution, and display brightness. This DCT quantization matrix is used in most recent standards for digital image compression (JPEG, MPEG, CCITT H.261). The second technique optimizes the DCT quantization matrix for each individual image, based on the contents of the image. This is accomplished by means of a model of visual sensitivity to compression artifacts. The third technique extends the first two techniques to the realm of wavelet compression. Together these two techniques will allow systematic perceptual optimization of image compression in NASA imaging systems. Many of the image management challenges faced by NASA are mirrored in the field of telemedicine. Here too there are severe demands for transmission and archiving of large image databases, and the imagery is ultimately used primarily by human observers, such as radiologists. In this presentation I will describe some of our preliminary explorations of the applications

  17. "The best is always yet to come": Relationship stages and processes among young LGBT couples.

    PubMed

    Macapagal, Kathryn; Greene, George J; Rivera, Zenaida; Mustanski, Brian

    2015-06-01

    Limited research has examined relationship development among lesbian, gay, bisexual, and transgender (LGBT) couples in emerging adulthood. A better understanding of LGBT couples can inform the development of relationship education programs that reflect their unique needs. The following questions guided this study: (a) What are the stages and processes during young LGBT couples' relationship development? and (b) How do these compare with existing literature on heterosexual adults? A secondary goal was to explore similarities and differences between couples assigned male (MAAB) and female at birth (FAAB). Thirty-six couples completed interviews on their relationship history. Qualitative analyses showed that relationship stages and processes were similar to past research on heterosexuals, but participants' subjective experiences reflected their LGBT identities and emerging adulthood, which exerted additional stress on the relationship. These factors also affected milestones indicative of commitment among heterosexual adults (e.g., introducing partner to family). Mixed methods analyses indicated that MAAB couples described negotiating relationship agreements and safe sex in more depth than FAAB couples. Relationship development models warrant modifications to consider the impact of sexual and gender identity and emerging adulthood when applied to young LGBT couples. These factors should be addressed in interventions to promote relationship health among young LGBT couples.

  18. Integrated two-stage chemically processing of rice straw cellulose to butyl levulinate.

    PubMed

    Elumalai, Sasikumar; Agarwal, Bhumica; Runge, Troy M; Sangwan, Rajender S

    2016-10-01

    A two-stage reaction system was developed to synthesize butyl levulinate (BL), a derivative chemical of levulinic acid, from agricultural residue (rice straw). A single reactor was employed during the first processing stage for the conversion of rice straw cellulose to levulinic acid (LA) in a novel co-solvent system consisting of dilute phosphoric acid and tetrahydrofuran. The highest yield of 10.8% wt. LA concentration (i.e., ∼42% of theoretical LA yield) with intermediate residuals concentration of 1.5% wt. glucose and 0.5% wt. 5-hydroxymethylfurfural (5-HMF) on dry weight basis of biomass was obtained at modest reaction conditions. During subsequent esterification reaction, approximately 7.8% wt. BL yield (at 89% conversion yield) was achieved from the solvent extracted precipitate containing majorly LA and residual 5-HMF in the presence of 0.5M sulfuric acid using n-butanol. Based on comparative esterification results obtained using commercial chemicals (LA and 5-HMF), apparently 5-HMF exhibited ∼8% wt. BL yield through direct synthesis in the presence of sulfuric acid using n-butanol under the same specified reaction conditions. Alongside, effectiveness of co-solvent treatment on rice straw for potential fermentable sugar release (glucose) was investigated by subjecting the respective post-reaction solid residues to enzymatic digestion using cellulase and yielded highest of 11% wt. per wt. solids (27% wt. glucose conversion efficiency), amongst solid residues underwent different processing conditions. PMID:27312640

  19. Two-stage fermentation process for enhanced mannitol production using Candida magnoliae mutant R9.

    PubMed

    Savergave, Laxman S; Gadre, Ramchandra V; Vaidya, Bhalchandra K; Jogdand, Vitthal V

    2013-02-01

    Mutants of Candida magnoliae NCIM 3470 were generated by treatment of ultra-violet radiations, ethyl methyl sulphonate and N-methyl-N'-nitro-N-nitrosoguanidine. Mutants with higher reductase activity were screened by means of 2,3,5-triphenyl tetrazolium chloride agar plate assay. Among the screened mutants, the mutant R9 produced maximum mannitol (i.e. 46 g l(-1)) in liquid fermentation medium containing 250 g l(-1) glucose and hence was selected for further experiments. Preliminary optimization studies were carried out on shake-flask level which increased the mannitol production to 60 g l(-1) in liquid fermentation medium containing 300 g l(-1) glucose. A two-stage fermentation process comprising of growth phase and production phase was employed. During the growth phase, glucose was supplemented and aerobic conditions were maintained. Thereafter, the production phase was initiated by supplementing fructose and switching to anaerobic conditions by discontinuing aeration and decreasing the speed of agitation. The strategy of two-stage fermentation significantly enhanced the production of mannitol up to 240 g l(-1), which is the highest among all fermentative production processes and corresponds to 81 % yield and 4 g l(-1 )h(-1) productivity without formation of any by-product.

  20. "The best is always yet to come": Relationship stages and processes among young LGBT couples.

    PubMed

    Macapagal, Kathryn; Greene, George J; Rivera, Zenaida; Mustanski, Brian

    2015-06-01

    Limited research has examined relationship development among lesbian, gay, bisexual, and transgender (LGBT) couples in emerging adulthood. A better understanding of LGBT couples can inform the development of relationship education programs that reflect their unique needs. The following questions guided this study: (a) What are the stages and processes during young LGBT couples' relationship development? and (b) How do these compare with existing literature on heterosexual adults? A secondary goal was to explore similarities and differences between couples assigned male (MAAB) and female at birth (FAAB). Thirty-six couples completed interviews on their relationship history. Qualitative analyses showed that relationship stages and processes were similar to past research on heterosexuals, but participants' subjective experiences reflected their LGBT identities and emerging adulthood, which exerted additional stress on the relationship. These factors also affected milestones indicative of commitment among heterosexual adults (e.g., introducing partner to family). Mixed methods analyses indicated that MAAB couples described negotiating relationship agreements and safe sex in more depth than FAAB couples. Relationship development models warrant modifications to consider the impact of sexual and gender identity and emerging adulthood when applied to young LGBT couples. These factors should be addressed in interventions to promote relationship health among young LGBT couples. PMID:26053345

  1. Production of Swedish Class I diesel using dual-stage process

    SciTech Connect

    Cooper, B.H.; Soegaard-Andersen, P.; Nielsen-Hannerup, P.

    1994-12-31

    In 1991, the Swedish Government proposed the introduction of three classes of diesel, each with a specific energy tax. Environmental Class 1 diesel (SCI) specifies a maximum aromatic content of 5 vol% and a maximum sulfur content of 10 wppm. Class 2 diesel (SCII) limits aromatics to max. 20 vol% and sulfur to max. 50 wppm, while Class 3 (SCIII) has no limit on aromatics and a maximum of 0.05 wt% sulfur. The difference in taxation levels for the three classes is considerable: Skr250/m{sup 3} (corresponding to approx. $6/bbl) between SCII and SCIII, and a further Skr200/m{sup 3} (corresponding to approx. $5/bbl) between SCI and SCII. Topsoee has developed a two-stage process for low-aromatics diesel production at low partial pressures of hydrogen. In the following, the application of this process concept is described for production of Swedish Class 1 diesel from North Sea gas oils.

  2. "Sightblind": perceptual deficits in the "intact" visual field.

    PubMed

    Bola, Michał; Gall, Carolin; Sabel, Bernhard A

    2013-01-01

    Unilateral visual cortex lesions caused by stroke or trauma lead to blindness in contralateral visual field - a condition called homonymous hemianopia. Although the visual field area processed by the uninjured hemisphere is thought to be "intact," it also exhibits marked perceptual deficits in contrast sensitivity, processing speed, and contour integration. Such patients are "sightblind" - their blindness reaches far beyond the primary scotoma. Studies showing perceptual deficits in patients' intact fields are reviewed and implications of these findings are discussed. It is concluded that consequences of partial blindness are greater than previously thought, since perceptual deficits in the "intact" field likely contribute to subjective vision loss in patients with visual field defect. This has important implications for vision diagnosis and rehabilitation. PMID:23805126

  3. Neurally Constrained Modeling of Perceptual Decision Making

    ERIC Educational Resources Information Center

    Purcell, Braden A.; Heitz, Richard P.; Cohen, Jeremiah Y.; Schall, Jeffrey D.; Logan, Gordon D.; Palmeri, Thomas J.

    2010-01-01

    Stochastic accumulator models account for response time in perceptual decision-making tasks by assuming that perceptual evidence accumulates to a threshold. The present investigation mapped the firing rate of frontal eye field (FEF) visual neurons onto perceptual evidence and the firing rate of FEF movement neurons onto evidence accumulation to…

  4. Multi-stage evolution process of large scale landslides at the Patanpunas stream, Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Lang; Lee, Kuo-Chen; Lo, Chia-Ming; Weng, Meng-Chia; Lee, Shun-Min

    2016-04-01

    This study used multi-temporal terrain and remote sensing images to investigate the geomorphological evolution of the Putanpunas stream caused by large-scale landslides over the last decade. We conducted an analysis of the landslides evolution process within the study area, which included a multi-temporal terrain analysis, remote sensing interpretation, surface displacement analysis, and mechanism investigation. By integrating the results from these analyses, we provided explanations for the topographic and geomorphologic action processes of the deep-seated landslides as well as the development of the potential collapsing mechanisms within the study area. Then, discrete element method was used to simulate the process of landslide movement and deposition. The results show that the evolution process of large-scale landslides in the Putanpunas stream can be divided into four stages, namely downcutting of the stream gully and decompression of the river gully in the early stage, creep and deformation of the rock slope, sliding surface development of the deformed bands in the rock strata, and movement of the sliding mass. The results of terrain analysis and interpretation show topographical changes in the alluvial fan downstream and the deposits in the midstream and downstream segments of the Putanpunas Stream between 2005 and 2009. In 2009, torrential rainfall induced large-scale landslides that greatly altered the terrain of the Putanpunas Stream and the alluvial fan. There still exists 7.2 × 107 m3 of unstable colluvium accumulated at the slope surface and stream gully within the upstream and midstream areas. In 2012, further large-scale landslides turned the colluvial layer into debris flows that cut across the Ryukyu Terraces downstream to the downstream segment of the Laonong Stream to the southwest. This greatly changed later debris flows and alluvial fan deposits. Key Words: large-scale landslides, multi-temporal terrain, remote sensing, discrete element method

  5. Is Perceptual Narrowing Too Narrow?

    ERIC Educational Resources Information Center

    Cashon, Cara H.; Denicola, Christopher A.

    2011-01-01

    There is a growing list of examples illustrating that infants are transitioning from having earlier abilities that appear more "universal," "broadly tuned," or "unconstrained" to having later abilities that appear more "specialized," "narrowly tuned," or "constrained." Perceptual narrowing, a well-known phenomenon related to face, speech, and…

  6. Perceptual Fading without Retinal Adaptation

    ERIC Educational Resources Information Center

    Hsieh, Po-Jang; Colas, Jaron T.

    2012-01-01

    A retinally stabilized object readily undergoes perceptual fading and disappears from consciousness. This startling phenomenon is commonly believed to arise from local bottom-up sensory adaptation to edge information that occurs early in the visual pathway, such as in the lateral geniculate nucleus of the thalamus or retinal ganglion cells. Here…

  7. Perceptual transparency from image deformation.

    PubMed

    Kawabe, Takahiro; Maruya, Kazushi; Nishida, Shin'ya

    2015-08-18

    Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid's surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of "invisible" transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation. PMID:26240313

  8. Perceptual Aspects of Cluttered Speech

    ERIC Educational Resources Information Center

    St. Louis, Kenneth O.; Myers, Florence L.; Faragasso, Kristine; Townsend, Paula S.; Gallaher, Amanda J.

    2004-01-01

    The purpose of this descriptive investigation was to explore perceptual judgments of speech naturalness, compared to judgments of articulation, language, disfluency, and speaking rate, in the speech of two youths who differed in cluttering severity. Two groups of listeners, 48 from New York and 48 from West Virginia, judged 93 speaking samples on…

  9. Perceptual Learning, Cognition, and Expertise

    ERIC Educational Resources Information Center

    Kellman, Philip J.; Massey, Christine M.

    2013-01-01

    Recent research indicates that perceptual learning (PL)--experience-induced changes in the way perceivers extract information--plays a larger role in complex cognitive tasks, including abstract and symbolic domains, than has been understood in theory or implemented in instruction. Here, we describe the involvement of PL in complex cognitive tasks…

  10. Ecotoxicity of materials from integrated two-stage liquefaction and Exxon Donor Solvent processes

    SciTech Connect

    Dauble, D.D.; Scott, A.J.; Lusty, E.W.; Thomas, B.L.; Hanf, R.W. Jr.

    1983-05-01

    Coal-derived materials from two coal conversion processes were screened for potential ecological toxicity. We examined the toxicity of materials from different engineering or process options to an aquatic invertebrate and also related potential hazard to relative concentration, composition, and stability of water soluble components. For materials tested from the Integrated Two-Stage Liquefaction (ITSL) process, only the LC finer (LCF) 650/sup 0/F distillate was highly soluble in water at 20/sup 0/C. The LCF feed and Total Liquid Product (TLP) were not in liquid state at 20/sup 0/C and were relatively insoluble in water. Relative hazard to daphnids from ITSL materials was as follows: LCF 650/sup 0/F distillate greater than or equal to LCF feed greater than or equal to TLP. For Exxon Donor Solvent (EDS) materials, process solvent produced in the bottoms recycle mode was more soluble in water than once-through process solvent and, hence, slightly more acutely toxic to daphnids. When compared to other coal liquids or petroleum products, the ITSL or EDS liquids were intermediate in toxicity; relative hazard ranged from 1/7 to 1/13 of the Solvent Refined Coal (SRC)-II distillable blend, but was several times greater than the relative hazard for No. 2 diesel fuel oil or Prudhoe Bay crude oil. Although compositonal differences in water-soluble fractions (WSF) were noted among materials, phenolics were the major compound class in all WSFs and probably the primary contributor to acute toxicity.

  11. Brief Report: Perceptual Load and the Autism Spectrum in Typically Developed Individuals

    ERIC Educational Resources Information Center

    Bayliss, Andrew P.; Kritikos, Ada

    2011-01-01

    A fundamental task of the cognitive system is to prioritize behaviourally relevant sensory inputs for processing at the expense of irrelevant inputs. In a study of neurotypical participants (n = 179), we utilized a brief flanker interference task while varying the perceptual load of the visual display. Typically, increasing perceptual load (i.e.,…

  12. Developmental Improvements in Perceptual Restoration: Can Young Children Reconstruct Missing Sounds in Noisy Environments?

    ERIC Educational Resources Information Center

    Winstone, Naomi; Davis, Alyson; De Bruyn, Bart

    2012-01-01

    Young children are frequently exposed to sounds such as speech and music in noisy listening conditions, which have the potential to disrupt their learning. Missing input that is masked by louder sounds can, under the right conditions, be "filled in" by the perceptual system using a process known as perceptual restoration. This experiment…

  13. Subjective Confidence in Perceptual Judgments: A Test of the Self-Consistency Model

    ERIC Educational Resources Information Center

    Koriat, Asher

    2011-01-01

    Two questions about subjective confidence in perceptual judgments are examined: the bases for these judgments and the reasons for their accuracy. Confidence in perceptual judgments has been claimed to rest on qualitatively different processes than confidence in memory tasks. However, predictions from a self-consistency model (SCM), which had been…

  14. Enhanced Perceptual Functioning in Autism: An Update, and Eight Principles of Autistic Perception

    ERIC Educational Resources Information Center

    Mottron, Laurent; Dawson, Michelle; Soulieres, Isabelle; Hubert, Benedicte; Burack, Jake

    2006-01-01

    We propose an "Enhanced Perceptual Functioning" model encompassing the main differences between autistic and non-autistic social and non-social perceptual processing: locally oriented visual and auditory perception, enhanced low-level discrimination, use of a more posterior network in "complex" visual tasks, enhanced perception of first order…

  15. Preseismic electromagnetic emissions: demystifying the features of the last stages of fracture process

    NASA Astrophysics Data System (ADS)

    Eftaxias, Konstantinos; Potirakis, Stelios M.; Peratzakis, Athanasios; Nomicos, Constantinos

    2013-04-01

    In recent years, the wind prevailing in the scientific community does not appear to be favorable for earthquake (EQ) prediction research, in particular for the research of short term prediction. Sometimes the arguments were extended to the extreme claim that any precursory activity is impossible. Importantly, negative views originate from certain systematically observed features, currently considered as "paradoxes". Fracture-induced electromagnetic emissions (EME) in a wide range of frequency bands are sensitive to the micro-structural chances. Thus, their study constitutes a nondestructive method for the monitoring of the evolution of damage process at the laboratory scale. It has been suggested that fracture induced MHz-kHz electromagnetic (EM) emissions, which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Despite fairly abundant evidence, EM precursors have not been adequately accepted as credible physical quantities. These negative views are enhanced by the fact that certain "puzzling features" are consistently observed in candidate pre-seismic EM emissions. More precisely: (i) EM silence in all frequency bands appears before the main seismic shock occurrence, as well as during the aftershock period. (ii) Absence of strong strain changes is observed during the emergence of EM precursors. We argue that experiments by means of EME at the large, geophysical, scale would probably reveal features of the last stages of failure process not clearly observable at the small, laboratory, scale, allowing thus the monitoring in real-time and step-by-step of the EQ generation. The observed EM precursors have been interpreted through a shift in thinking towards the basic science. Strict criteria have been established for the definition of an emerged EM anomaly as a pre-seismic one by means of a

  16. Enhancement of bioenergy production from organic wastes by two-stage anaerobic hydrogen and methane production process.

    PubMed

    Luo, Gang; Xie, Li; Zhou, Qi; Angelidaki, Irini

    2011-09-01

    The present study investigated a two-stage anaerobic hydrogen and methane process for increasing bioenergy production from organic wastes. A two-stage process with hydraulic retention time (HRT) 3d for hydrogen reactor and 12d for methane reactor, obtained 11% higher energy compared to a single-stage methanogenic process (HRT 15 d) under organic loading rate (OLR) 3 gVS/(L d). The two-stage process was still stable when the OLR was increased to 4.5 gVS/(Ld), while the single-stage process failed. The study further revealed that by changing the HRT(hydrogen):HRT(methane) ratio of the two-stage process from 3:12 to 1:14, 6.7%, more energy could be obtained. Microbial community analysis indicated that the dominant bacterial species were different in the hydrogen reactors (Thermoanaerobacterium thermosaccharolyticum-like species) and methane reactors (Clostridium thermocellum-like species). The changes of substrates and HRT did not change the dominant species. The archaeal community structures in methane reactors were similar both in single- and two- stage reactors, with acetoclastic methanogens Methanosarcina acetivorans-like organisms as the dominant species.

  17. Beyond perceptual expertise: revisiting the neural substrates of expert object recognition

    PubMed Central

    Harel, Assaf; Kravitz, Dwight; Baker, Chris I.

    2013-01-01

    Real-world expertise provides a valuable opportunity to understand how experience shapes human behavior and neural function. In the visual domain, the study of expert object recognition, such as in car enthusiasts or bird watchers, has produced a large, growing, and often-controversial literature. Here, we synthesize this literature, focusing primarily on results from functional brain imaging, and propose an interactive framework that incorporates the impact of high-level factors, such as attention and conceptual knowledge, in supporting expertise. This framework contrasts with the perceptual view of object expertise that has concentrated largely on stimulus-driven processing in visual cortex. One prominent version of this perceptual account has almost exclusively focused on the relation of expertise to face processing and, in terms of the neural substrates, has centered on face-selective cortical regions such as the Fusiform Face Area (FFA). We discuss the limitations of this face-centric approach as well as the more general perceptual view, and highlight that expert related activity is: (i) found throughout visual cortex, not just FFA, with a strong relationship between neural response and behavioral expertise even in the earliest stages of visual processing, (ii) found outside visual cortex in areas such as parietal and prefrontal cortices, and (iii) modulated by the attentional engagement of the observer suggesting that it is neither automatic nor driven solely by stimulus properties. These findings strongly support a framework in which object expertise emerges from extensive interactions within and between the visual system and other cognitive systems, resulting in widespread, distributed patterns of expertise-related activity across the entire cortex. PMID:24409134

  18. The structural features of hemicelluloses dissolved out at different cooking stages of active oxygen cooking process.

    PubMed

    Shi, Jianbin; Yang, Qiulin; Lin, Lu

    2014-04-15

    This work described the morphologic changes of corn stalk and the structural characterization of its hemicelluloses dissolved in yellow liquor at different cooking stages. The results showed that active oxygen cooking process was an efficient method to depolymerize the corn stalk into cellulose, hemicelluloses, and lignin as a pretreatment of biomass conversion. This cooking process can also be divided into three phases: bulk delignification, extended delignification, and residual delignification. During the heating-up period 57.67% of hemicelluloses and 62.31% of lignin were removed from the raw material. However, only 15% of hemicelluloses and 23.21% of lignin were removed during at temperature' period. The hemicelluloses from the corn stalk and yellow liquor were composed of (1→4)-β-D-xylopyranose backbones substituted with α-l-arabinofuranosyl, 4-O-methyl-α-D-glucuronic acid, and some methoxyl residues. The backbones of hemicelluloses were gradually cleaved during the cooking process. The acetyl groups substituted with xylopyranosyl residues were completely cleaved during the cooking process.

  19. Neural mechanisms underlying the induction and relief of perceptual curiosity.

    PubMed

    Jepma, Marieke; Verdonschot, Rinus G; van Steenbergen, Henk; Rombouts, Serge A R B; Nieuwenhuis, Sander

    2012-01-01

    Curiosity is one of the most basic biological drives in both animals and humans, and has been identified as a key motive for learning and discovery. Despite the importance of curiosity and related behaviors, the topic has been largely neglected in human neuroscience; hence little is known about the neurobiological mechanisms underlying curiosity. We used functional magnetic resonance imaging (fMRI) to investigate what happens in our brain during the induction and subsequent relief of perceptual curiosity. Our core findings were that (1) the induction of perceptual curiosity, through the presentation of ambiguous visual input, activated the anterior insula and anterior cingulate cortex (ACC), brain regions sensitive to conflict and arousal; (2) the relief of perceptual curiosity, through visual disambiguation, activated regions of the striatum that have been related to reward processing; and (3) the relief of perceptual curiosity was associated with hippocampal activation and enhanced incidental memory. These findings provide the first demonstration of the neural basis of human perceptual curiosity. Our results provide neurobiological support for a classic psychological theory of curiosity, which holds that curiosity is an aversive condition of increased arousal whose termination is rewarding and facilitates memory.

  20. Differential frontal involvement in shifts of internal and perceptual attention

    PubMed Central

    Tanoue, Ryan T.; Jones, Kevin T.; Peterson, Dwight J.; Berryhill, Marian E.

    2012-01-01

    Background Perceptual attention enhances the processing of items in the environment, whereas internal attention enhances processing of items encoded in visual working memory. In perceptual and internal attention cueing paradigms, cues indicate the to-be-probed item before (pre-cueing) or after (retro-cueing) the memory display, respectively. Pre- and retro- cues confer similar behavioral accuracy benefits (pre-: 14–19%, retro-: 11–17%) and neuroimaging data show that they activate overlapping frontoparietal networks (1). Yet reports of behavioral and neuroimaging differences suggest that pre- and retro-cueing differentially recruit frontal and parietal cortices (1). Objective/Hypothesis This study examined whether perceptual and internal attention are equally disrupted by neurostimulation to frontal and parietal cortices. We hypothesized that neurostimulation applied to frontal cortex would disrupt internal attention to a greater extent than perceptual attention. Methods Cathodal transcranial direct current stimulation (tDCS) was applied to frontal or parietal cortices. After stimulation, participants completed a change detection task coupled with either pre- or retro- cues. Results Cathodal tDCS across site (frontal, parietal) hindered performance. However, frontal tDCS had a greater negative impact on the retro-cued trials demonstrating greater frontal involvement during shifts of internal attention. Conclusions These results complement the neuroimaging data and provide further evidence suggesting that perceptual and internal attention are not identical processes. We conclude that although internal and perceptual attention are mediated by similar frontoparietal networks, the weight of contribution of these structures differs, with internal attention relying more heavily on the frontal cortex. PMID:23266133

  1. Visual Search Targeting Either Local or Global Perceptual Processes Differs as a Function of Autistic-Like Traits in the Typically Developing Population

    ERIC Educational Resources Information Center

    Almeida, Renita A.; Dickinson, J. Edwin; Maybery, Murray T.; Badcock, Johanna C.; Badcock, David R.

    2013-01-01

    Relative to low scorers, high scorers on the Autism-Spectrum Quotient (AQ) show enhanced performance on the Embedded Figures Test and the Radial Frequency search task (RFST), which has been attributed to both enhanced local processing and differences in combining global percepts. We investigate the role of local and global processing further using…

  2. Dynamics of Active Sensing and perceptual selection.

    PubMed

    Schroeder, Charles E; Wilson, Donald A; Radman, Thomas; Scharfman, Helen; Lakatos, Peter

    2010-04-01

    Sensory processing is often regarded as a passive process in which biological receptors like photoreceptors and mechanoreceptors transduce physical energy into a neural code. Recent findings, however, suggest that: first, most sensory processing is active, and largely determined by motor/attentional sampling routines; second, owing to rhythmicity in the motor routine, as well as to its entrainment of ambient rhythms in sensory regions, sensory inflow tends to be rhythmic; third, attentional manipulation of rhythms in sensory pathways is instrumental to perceptual selection. These observations outline the essentials of an Active Sensing paradigm, and argue for increased emphasis on the study of sensory processes as specific to the dynamic motor/attentional context in which inputs are acquired. PMID:20307966

  3. Dynamics of Active Sensing and Perceptual Selection

    PubMed Central

    Schroeder, Charles E; Wilson, Donald A.; Radman, Thomas; Scharfman, Helen; Lakatos, Peter

    2010-01-01

    Sensory processing is often regarded as a passive process in which a biological sensors like photo- and mechanoreceptors transducer physical energy into a neural code. Recent findings, however, suggest that: 1) most sensory processing is active, and largely determined by motor/attentional sampling routines, 2) due to rhythmicity in the motor routine, as well as to its entrainment of ambient rhythms in sensory regions, sensory inflow tends to be rhythmic, and 3) attentional manipulation of rhythms in sensory pathways is instrumental to perceptual selection. These observations outline the essentials of an Active Sensing paradigm, and argue for increased emphasis on the study of sensory processes as specific to the dynamic motor/attentional context in which inputs are acquired. PMID:20307966

  4. Preliminary chemical analysis and biological testing of materials from the HRI catalytic two-stage liquefaction (CTSL) process. [Aliphatic hydrocarbons

    SciTech Connect

    Later, D.W.; Wilson, B.W.

    1985-01-01

    Coal-derived materials from experimental runs of Hydrocarbon Research Incorporated's (HRI) catalytic two-stage liquefaction (CTSL) process were chemically characterized and screened for microbial mutagenicity. This process differs from two-stage coal liquefaction processes in that catalyst is used in both stages. Samples from both the first and second stages were class-fractionated by alumina adsorption chromatography. The fractions were analyzed by capillary column gas chromatography; gas chromatography/mass spectrometry; direct probe, low voltage mass spectrometry; and proton nuclear magnetic resonance spectrometry. Mutagenicity assays were performed with the crude and class fractions in Salmonella typhimurium, TA98. Preliminary results of chemical analyses indicate that >80% CTSL materials from both process stages were aliphatic hydrocarbon and polynuclear aromatic hydrocarbon (PAH) compounds. Furthermore, the gross and specific chemical composition of process materials from the first stage were very similar to those of the second stage. In general, the unfractionated materials were only slightly active in the TA98 mutagenicity assay. Like other coal liquefaction materials investigated in this laboratory, the nitrogen-containing polycyclic aromatic compound (N-PAC) class fractions were responsible for the bulk of the mutagenic activity of the crudes. Finally, it was shown that this activity correlated with the presence of amino-PAH. 20 figures, 9 tables.

  5. Enhanced coproduction of hydrogen and methane from cornstalks by a three-stage anaerobic fermentation process integrated with alkaline hydrolysis.

    PubMed

    Cheng, Xi-Yu; Liu, Chun-Zhao

    2012-01-01

    A three-stage anaerobic fermentation process including H(2) fermentation I, H(2) fermentation II, methane fermentation was developed for the coproduction of hydrogen and methane from cornstalks. Hydrogen production from cornstalks using direct microbial conversion by Clostridium thermocellum 7072 was markedly enhanced in the two-stage thermophilic hydrogen fermentation process integrated with alkaline treatment. The highest total hydrogen yield from cornstalks in the two-stage fermentation process reached 74.4 mL/g-cornstalk. The hydrogen fermentation effluents and alkaline hydrolyzate were further used for methane fermentation by anaerobic granular sludge, and the total methane yield reached 205.8 mL/g-cornstalk. The total energy recovery in the three-stage anaerobic fermentation process integrated with alkaline hydrolysis reached 70.0%.

  6. Unconsciously elicited perceptual prior

    PubMed Central

    Chang, Raymond; Baria, Alexis T.; Flounders, Matthew W.; He, Biyu J.

    2016-01-01

    Increasing evidence over the past decade suggests that vision is not simply a passive, feed-forward process in which cortical areas relay progressively more abstract information to those higher up in the visual hierarchy, but rather an inferential process with top-down processes actively guiding and shaping perception. However, one major question that persists is whether such processes can be influenced by unconsciously perceived stimuli. Recent psychophysics and neuroimaging studies have revealed that while consciously perceived stimuli elicit stronger responses in higher visual and frontoparietal areas than those that fail to reach conscious awareness, the latter can still drive high-level brain and behavioral responses. We investigated whether unconscious processing of a masked natural image could facilitate subsequent conscious recognition of its degraded counterpart (a black-and-white “Mooney” image) presented many seconds later. We found that this is indeed the case, suggesting that conscious vision may be influenced by priors established by unconscious processing of a fleeting image. PMID:27595010

  7. Early Stages of Sensory Processing, but Not Semantic Integration, Are Altered in Dyslexic Adults

    PubMed Central

    Silva, Patrícia B.; Ueki, Karen; Oliveira, Darlene G.; Boggio, Paulo S.; Macedo, Elizeu C.

    2016-01-01

    The aim of this study was to verify which stages of language processing are impaired in individuals with dyslexia. For this, a visual-auditory crossmodal task with semantic judgment was used. The P100 potentials were chosen, related to visual processing and initial integration, and N400 potentials related to semantic processing. Based on visual-auditory crossmodal studies, it is understood that dyslexic individuals present impairments in the integration of these two types of tasks and impairments in processing spoken and musical auditory information. The present study sought to investigate and compare the performance of 32 adult participants (14 individuals with dyslexia), in semantic processing tasks in two situations with auditory stimuli: sentences and music, with integrated visual stimuli (pictures). From the analysis of the accuracy, both the sentence and the music blocks showed significant effects on the congruency variable, with both groups having higher scores for the incongruent items than for the congruent ones. Furthermore, there was also a group effect when the priming was music, with the dyslexic group showing an inferior performance to the control group, demonstrating greater impairments in processing when the priming was music. Regarding the reaction time variable, a group effect in music and sentence priming was found, with the dyslexic group being slower than the control group. The N400 and P100 components were analyzed. In items with judgment and music priming, a group effect was observed for the amplitude of the P100, with higher means produced by individuals with dyslexia, corroborating the literature that individuals with dyslexia have difficulties in early information processing. A congruency effect was observed in the items with music priming, with greater P100 amplitudes found in incongruous situations. Analyses of the N400 component showed the congruency effect for amplitude in both types of priming, with the mean amplitude for incongruent

  8. Early Stages of Sensory Processing, but Not Semantic Integration, Are Altered in Dyslexic Adults.

    PubMed

    Silva, Patrícia B; Ueki, Karen; Oliveira, Darlene G; Boggio, Paulo S; Macedo, Elizeu C

    2016-01-01

    The aim of this study was to verify which stages of language processing are impaired in individuals with dyslexia. For this, a visual-auditory crossmodal task with semantic judgment was used. The P100 potentials were chosen, related to visual processing and initial integration, and N400 potentials related to semantic processing. Based on visual-auditory crossmodal studies, it is understood that dyslexic individuals present impairments in the integration of these two types of tasks and impairments in processing spoken and musical auditory information. The present study sought to investigate and compare the performance of 32 adult participants (14 individuals with dyslexia), in semantic processing tasks in two situations with auditory stimuli: sentences and music, with integrated visual stimuli (pictures). From the analysis of the accuracy, both the sentence and the music blocks showed significant effects on the congruency variable, with both groups having higher scores for the incongruent items than for the congruent ones. Furthermore, there was also a group effect when the priming was music, with the dyslexic group showing an inferior performance to the control group, demonstrating greater impairments in processing when the priming was music. Regarding the reaction time variable, a group effect in music and sentence priming was found, with the dyslexic group being slower than the control group. The N400 and P100 components were analyzed. In items with judgment and music priming, a group effect was observed for the amplitude of the P100, with higher means produced by individuals with dyslexia, corroborating the literature that individuals with dyslexia have difficulties in early information processing. A congruency effect was observed in the items with music priming, with greater P100 amplitudes found in incongruous situations. Analyses of the N400 component showed the congruency effect for amplitude in both types of priming, with the mean amplitude for incongruent

  9. Referenceless Prediction of Perceptual Fog Density and Perceptual Image Defogging.

    PubMed

    Choi, Lark Kwon; You, Jaehee; Bovik, Alan Conrad

    2015-11-01

    We propose a referenceless perceptual fog density prediction model based on natural scene statistics (NSS) and fog aware statistical features. The proposed model, called Fog Aware Density Evaluator (FADE), predicts the visibility of a foggy scene from a single image without reference to a corresponding fog-free image, without dependence on salient objects in a scene, without side geographical camera information, without estimating a depth-dependent transmission map, and without training on human-rated judgments. FADE only makes use of measurable deviations from statistical regularities observed in natural foggy and fog-free images. Fog aware statistical features that define the perceptual fog density index derive from a space domain NSS model and the observed characteristics of foggy images. FADE not only predicts perceptual fog density for the entire image, but also provides a local fog density index for each patch. The predicted fog density using FADE correlates well with human judgments of fog density taken in a subjective study on a large foggy image database. As applications, FADE not only accurately assesses the performance of defogging algorithms designed to enhance the visibility of foggy images, but also is well suited for image defogging. A new FADE-based referenceless perceptual image defogging, dubbed DEnsity of Fog Assessment-based DEfogger (DEFADE) achieves better results for darker, denser foggy images as well as on standard foggy images than the state of the art defogging methods. A software release of FADE and DEFADE is available online for public use: http://live.ece.utexas.edu/research/fog/index.html.

  10. The perceptual effects of learning object categories that predict perceptual goals

    PubMed Central

    Van Gulick, Ana E.; Gauthier, Isabel

    2014-01-01

    In classic category learning studies, subjects typically learn to assign items to one of two categories, with no further distinction between how items on each side of the category boundary should be treated. In real life, however, we often learn categories that dictate further processing goals, for instance with objects in only one category requiring further individuation. Using methods from category learning and perceptual expertise, we studied the perceptual consequences of experience with objects in tasks that rely on attention to different dimensions in different parts of the space. In two experiments, subjects first learned to categorize complex objects from a single morphspace into two categories based on one morph dimension, and then learned to perform a different task, either naming or a local feature judgment, for each of the two categories. A same-different discrimination test before and after each training measured sensitivity to feature dimensions of the space. After initial categorization, sensitivity increased along the category-diagnostic dimension. After task association, sensitivity increased more for the category that was named, especially along the non-diagnostic dimension. The results demonstrate that local attentional weights, associated with individual exemplars as a function of task requirements, can have lasting effects on perceptual representations. PMID:24820671

  11. Stored color-form knowledge modulates perceptual sensitivity in search.

    PubMed

    Wildegger, Theresa; Riddoch, Jane; Humphreys, Glyn W

    2015-05-01

    We used signal detection analysis to examine the effects of stored color-form knowledge on visual search. Across four experiments, we showed robust effects of stored color-form knowledge on perceptual sensitivity, whereas the effects on response criteria varied. The effects on perceptual sensitivity were stronger when multiple items were present and when the color fell on the surface of the object. The benefit was found even when the correctly colored target had a low probability of occurrence in the experiment. In addition, the benefit was present across different display sizes, and the effects of increasing the exposure duration on detecting correctly colored targets were equal across different sizes of the display. The data suggest that color-form conjunctions are detected efficiently to activate stored color-form knowledge, and that this knowledge then influences early perceptual processing in a bottom-up manner. We discuss the implications for understanding the coding of conjunctive relations. PMID:25772101

  12. Temporal coordination of perceptual algorithms for mobile robot navigation

    SciTech Connect

    Arkin, R.C.; MacKenzie, D. . Mobile Robot Lab.)

    1994-06-01

    A methodology for integrating multiple perceptual algorithms within a reactive robotic control system is presented. A model using finite state acceptors is developed as a means for expressing perceptual processing over space and time in the context of a particular motor behavior. This model can be utilized for a wide range of perceptual sequencing problems. The feasibility of this method is demonstrated in two separate implementations. The first is in the context of mobile robot docking where the mobile robot uses four different vision and ultrasonic algorithms to position itself relative to a docking workstation over a long-range course. The second uses vision, IR beacon, and ultrasonic algorithms to park the robot next to a desired plastic pole randomly placed within an arena.

  13. Enhanced bio-energy recovery in a two-stage hydrogen/methane fermentation process.

    PubMed

    Lee, M J; Song, J H; Hwang, S J

    2009-01-01

    A two-stage hydrogen/methane fermentation process has emerged as a feasible engineering system to recover bio-energy from wastewater. Hydrogen-producing bacteria (HPB) generate hydrogen from readily available carbohydrates, and organic acids produced during the hydrogen fermentation step can be degraded to generate methane in the following step. Three strong acids, HCl, H(2)SO(4), and HNO(3), were tested to determine the appropriate pre-treatment method for enhanced hydrogen production. The hydrogen production rates of 230, 290, and 20 L/kg(-glucose)/day was observed for the sludge treated with HCl, H(2)SO(4), and HNO(3), respectively, indicating that the acid pre-treatment using either HCl or H(2)SO(4) resulted in a significant increase in hydrogen production. The fluorescent in situ hybridization method indicated that the acid pre-treatment selectively enriched HPB including Clostridium sp. of cluster I from inoculum sludge. After hydrogen fermentation was terminated, the sludge was introduced to a methane fermentation reactor. This experiment showed methane production rates of 100, 30, and 13 L/kg(-glucose)/day for the sludge pre-treated with HCl, H(2)SO(4), and HNO(3), respectively, implying that both sulfate and nitrate inhibited the activity of methane-producing bacteria. Consequently, the acid pre-treatment might be a feasible option to enhance biogas recovery in the two-stage fermentation process, and HCl was selected as the optimal strong acid for the enrichment of HPB and the continuous production of methane.

  14. Out of mind, out of sight: perceptual consequences of memory suppression.

    PubMed

    Kim, Kyungmi; Yi, Do-Joon

    2013-04-01

    In the present study, the effect of memory suppression on subsequent perceptual processing of visual objects was examined within a modified think/no-think paradigm. Suppressing memories of visual objects significantly impaired subsequent perceptual identification of those objects when they were briefly encountered (Experiment 1) and when they were presented in noise (Experiment 2), relative to performance on baseline items for which participants did not undergo suppression training. However, in Experiment 3, when perceptual identification was performed on mirror-reversed images of to-be-suppressed objects, no impairment was observed. These findings, analogous to those showing forgetting of suppressed words in long-term memory, suggest that suppressing memories of visual objects might be mediated by direct inhibition of perceptual representations, which, in turn, impairs later perception of them. This study provides strong support for the role of inhibitory mechanisms in memory control and suggests a tight link between higher-order cognitive operations and perceptual processing.

  15. Enhanced perceptual functioning in autism: an update, and eight principles of autistic perception.

    PubMed

    Mottron, Laurent; Dawson, Michelle; Soulières, Isabelle; Hubert, Benedicte; Burack, Jake

    2006-01-01

    We propose an "Enhanced Perceptual Functioning" model encompassing the main differences between autistic and non-autistic social and non-social perceptual processing: locally oriented visual and auditory perception, enhanced low-level discrimination, use of a more posterior network in "complex" visual tasks, enhanced perception of first order static stimuli, diminished perception of complex movement, autonomy of low-level information processing toward higher-order operations, and differential relation between perception and general intelligence. Increased perceptual expertise may be implicated in the choice of special ability in savant autistics, and in the variability of apparent presentations within PDD (autism with and without typical speech, Asperger syndrome) in non-savant autistics. The overfunctioning of brain regions typically involved in primary perceptual functions may explain the autistic perceptual endophenotype.

  16. If it changes it must be a process: study of emotion and coping during three stages of a college examination.

    PubMed

    Folkman, S; Lazarus, R S

    1985-01-01

    This natural experiment provides substantial evidence for the following major themes, which are based on a cognitively oriented, process-centered theory of stress and coping: First, a stressful encounter should be viewed as a dynamic, unfolding process, not as a static, unitary event. Emotion and coping (including the use of social support) were assessed at three stages of a midterm examination: the anticipation stage before the exam, the waiting stage after the exam and before grades were announced, and after grades were posted. For the group as a whole there were significant changes in emotions and coping (including the use of social support) across the three stages. Second, people experience seemingly contradictory emotions and states of mind during every stage of an encounter. In this study, for example, subjects experienced both threat emotions and challege emotions. The complexity of emotions and their cognitive appraisals reflects ambiguity regarding the multifaceted nature of the exam and its meanings, especially during the anticipation stage. Third, coping is a complex process. On the average, subjects used combinations of most of the available forms of problem-focused coping and emotion-focused coping at every stage of the exam. Different forms of coping were salient during the anticipation and waiting stages. Problem-focused coping and emphasizing the positive were more prominent during the former, and distancing more prominent during the latter. Finally, despite normatively shared emotional reactions at each stage, substantial individual differences remained. Using selected appraisal and coping variables, and taking grade point averages (GPA) into account, approximately 48% of the variances in threat and challenge emotions at the anticipation stage was explained. Controlling for variance due to the grade received, appraisal, and coping variables accounted for 28% of the variance in positive and negative emotions at the outcome stage. Including grade, 57

  17. Food Behavior Change in Late-Life Widowhood: A Two-Stage Process

    PubMed Central

    Vesnaver, Elisabeth; Keller, Heather H.; Sutherland, Olga; Maitland, Scott B.; Locher, Julie L.

    2015-01-01

    Widowhood is a common life event for married older women. Prior research has found disruptions in eating behaviors to be common among widows. Little is known about the process underlying these disruptions. The aim of this study was to generate a theoretical understanding of the changing food behaviors of older women during the transition of widowhood. Qualitative methods based on constructivist grounded theory guided by a critical realist worldview were used. Individual active interviews were conducted with 15 community-living women, aged 71 to 86 years, living alone, and widowed six months to 15 years at the time of the interview. Participants described a variety of educational backgrounds and levels of health, were mainly white and of Canadian or European descent, and reported sufficient income to meet their needs. The loss of regular shared meals initiated a two-stage process whereby women first fall into new patterns and then re-establish the personal food system, thus enabling women to redirect their food system from one that satisfied the couple to one that satisfied their personal food needs. Influences on the trajectory of the change process included the couple’s food system, experience with nutritional care, food-related values, and food-related resources. Implications for research and practice are discussed. PMID:26232138

  18. Double-stage Dehumidification achieved in 2-rotor Desiccant Cooling Process

    NASA Astrophysics Data System (ADS)

    Asada, Toshinobu; Kodama, Akio

    A multi-divided rotary adsorber was proposed to realize a double-stage dehumidification in 2-rotor desiccant cooling process. In this process, once dehumidified and cooled air was dehumidified again at the different adsorption zone of the same desiccant rotor. Four process flow configurations were experimentally tested for investigations of the appropriate outside air inlet position and rotating directions of the rotary adsorber and rotary heat exchanger. It was found that dehumidifying performance was strongly influenced by the supply position of outside air to the adsorbent rotor. Humid outside air should be supplied to the latter half of the adsorption zone and once dehumidified air should be sent to the first half of the adsorption zone. This is because the increase in the amount adsorbed at the first half of the adsorption step resulted in a poor adsorbabilty at the latter half of the adsorption step for the once dehumidified dry air. Therefore, the effective use of the adsorbent rotor could be done by considering the angular distribution of the amount of adsorbed. Consequently, 30% larger amount of dehumidification than that of conventional processes under a humid summer condition was confirmed. Regarding the product air temperature, the process configurations at which secondary dehumidified air was cooled at the first half of the sensible rotor produced roughly 5 °C lower temperature air than that of the other. This implied that the directions of rotation of the adsorbent rotor and the rotary heat exchanger, or dehumidification - cooling sequence, also had a great impact on the product air condition.

  19. JPEG 2000 Encoding with Perceptual Distortion Control

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Liu, Zhen; Karam, Lina J.

    2008-01-01

    An alternative approach has been devised for encoding image data in compliance with JPEG 2000, the most recent still-image data-compression standard of the Joint Photographic Experts Group. Heretofore, JPEG 2000 encoding has been implemented by several related schemes classified as rate-based distortion-minimization encoding. In each of these schemes, the end user specifies a desired bit rate and the encoding algorithm strives to attain that rate while minimizing a mean squared error (MSE). While rate-based distortion minimization is appropriate for transmitting data over a limited-bandwidth channel, it is not the best approach for applications in which the perceptual quality of reconstructed images is a major consideration. A better approach for such applications is the present alternative one, denoted perceptual distortion control, in which the encoding algorithm strives to compress data to the lowest bit rate that yields at least a specified level of perceptual image quality. Some additional background information on JPEG 2000 is prerequisite to a meaningful summary of JPEG encoding with perceptual distortion control. The JPEG 2000 encoding process includes two subprocesses known as tier-1 and tier-2 coding. In order to minimize the MSE for the desired bit rate, a rate-distortion- optimization subprocess is introduced between the tier-1 and tier-2 subprocesses. In tier-1 coding, each coding block is independently bit-plane coded from the most-significant-bit (MSB) plane to the least-significant-bit (LSB) plane, using three coding passes (except for the MSB plane, which is coded using only one "clean up" coding pass). For M bit planes, this subprocess involves a total number of (3M - 2) coding passes. An embedded bit stream is then generated for each coding block. Information on the reduction in distortion and the increase in the bit rate associated with each coding pass is collected. This information is then used in a rate-control procedure to determine the

  20. Further Evidence for the Developmental Stages of Language Learning and Processability

    ERIC Educational Resources Information Center

    Doman, Evelyn

    2012-01-01

    Few, if any, researchers would deny the existence of the developmental stages of language learning. However, there are questions about the applicability and the importance of the stages in pedagogy. Up to this point, these questions regarding the ESL (English as a second language) stages have never been addressed in a Japanese post-secondary…

  1. Early Perceptual Learning

    ERIC Educational Resources Information Center

    Goldstone, Robert L.; Son, Ji Y.; Byrge, Lisa

    2011-01-01

    Bhatt and Quinn (2011) present a compelling case that human learning is "early" in two very different, but interacting, senses. Learning is "developmentally" early in that even infants show strikingly robust adaptation to the structures present in their world. Learning is also early in an information processing sense because infants adapt their…

  2. Perceptual Pressures on Lenition

    ERIC Educational Resources Information Center

    Kaplan, Abby

    2011-01-01

    The phonological processes known as "lenition" have traditionally been explained as articulatory effort reduction. However, such a motivation for lenition has never been directly demonstrated; in addition, there are reasons to doubt the articulatory explanation.This paper focuses on a particular type of lenition (intervocalic spirantization of…

  3. Striatal activation as a neural link between cognitive and perceptual flexibility.

    PubMed

    Sekutowicz, Maria; Schmack, Katharina; Steimke, Rosa; Paschke, Lena; Sterzer, Philipp; Walter, Henrik; Stelzel, Christine

    2016-11-01

    Our brain continuously evaluates different perceptual interpretations of the available sensory data in order to enable flexible updates of conscious experience. Individuals' perceptual flexibility can be assessed using ambiguous stimuli that cause our perception to continuously switch between two mutually exclusive interpretations. Neural processes underlying perceptual switching are thought to involve the visual cortex, but also non-sensory brain circuits that have been implicated in cognitive processes, such as frontal and parietal regions. Perceptual flexibility varies strongly between individuals and has been related to dopaminergic neurotransmission. Likewise, there is also considerable individual variability in tasks that require flexibility in cognition, and dopamine-dependent striato-frontal signals have been associated with processes promoting cognitive flexibility. Given the anatomical and neurochemical similarities with regard to perceptual and cognitive flexibility, we here probed whether individual differences in perceptual flexibility during bistable perception are related to individual cognitive flexibility associated neural correlates. 126 healthy individuals performed rule-based task switching during functional magnetic resonance imaging (fMRI) and reported perceptual switching during the viewing of a modified version of the Necker cube. Mean phase duration as measure of perceptual flexibility correlated with task-switching associated activity in the right putamen as part of the basal ganglia. In addition, we found a tentative correlation between perceptual and cognitive flexibility. These results indicate that individual differences in cognitive flexibility and associated fronto-striatal processing contribute to differences in perceptual flexibility. Our findings thus provide empirical support for the general notion of shared mechanisms between perception and cognition.

  4. Perceptual Adaptation of Voice Gender Discrimination with Spectrally Shifted Vowels

    ERIC Educational Resources Information Center

    Li, Tianhao; Fu, Qian-Jie

    2011-01-01

    Purpose: To determine whether perceptual adaptation improves voice gender discrimination of spectrally shifted vowels and, if so, which acoustic cues contribute to the improvement. Method: Voice gender discrimination was measured for 10 normal-hearing subjects, during 5 days of adaptation to spectrally shifted vowels, produced by processing the…

  5. Cognitive-Perceptual Examination of Remediation Approaches to Hypokinetic Dysarthria

    ERIC Educational Resources Information Center

    McAuliffe, Megan J.; Kerr, Sarah E.; Gibson, Elizabeth M. R.; Anderson, Tim; LaShell, Patrick J.

    2014-01-01

    Purpose: To determine how increased vocal loudness and reduced speech rate affect listeners' cognitive-perceptual processing of hypokinetic dysarthric speech associated with Parkinson's disease. Method: Fifty-one healthy listener participants completed a speech perception experiment. Listeners repeated phrases produced by 5 individuals…

  6. Perceptual uncertainty is a property of the cognitive system.

    PubMed

    Perea, Manuel; Carreiras, Manuel

    2012-10-01

    We qualify Frost's proposals regarding letter-position coding in visual word recognition and the universal model of reading. First, we show that perceptual uncertainty regarding letter position is not tied to European languages-instead it is a general property of the cognitive system. Second, we argue that a universal model of reading should incorporate a developmental view of the reading process.

  7. Subjective Perceptual Distortions and Visual Dysfunction in Children with Autism

    ERIC Educational Resources Information Center

    Davis, Rebecca A. O.; Bockbrader, Marcia A.; Murphy, Robin R.; Hetrick, William P.; O'Donnell, Brian F.

    2006-01-01

    Case reports and sensory inventories suggest that autism involves sensory processing anomalies. Behavioral tests indicate impaired motion and normal form perception in autism. The present study used first-person accounts to investigate perceptual anomalies and related subjective to psychophysical measures. Nine high-functioning children with…

  8. Attentional Modulation of Perceptual Comparison for Feature Binding

    ERIC Educational Resources Information Center

    Kuo, Bo-Cheng; Rotshtein, Pia; Yeh, Yei-Yu

    2011-01-01

    We investigated the neural correlates of attentional modulation in the perceptual comparison process for detecting feature-binding changes in an event-related functional magnetic resonance imaging (fMRI) experiment. Participants performed a variant of a cued change detection task. They viewed a memory array, a spatial retro-cue, and later a probe…

  9. Prediction Error Associated with the Perceptual Segmentation of Naturalistic Events

    ERIC Educational Resources Information Center

    Zacks, Jeffrey M.; Kurby, Christopher A.; Eisenberg, Michelle L.; Haroutunian, Nayiri

    2011-01-01

    Predicting the near future is important for survival and plays a central role in theories of perception, language processing, and learning. Prediction failures may be particularly important for initiating the updating of perceptual and memory systems and, thus, for the subjective experience of events. Here, we asked observers to make predictions…

  10. Chinese and English Infants' Tone Perception: Evidence for Perceptual Reorganization

    ERIC Educational Resources Information Center

    Mattock, Karen; Burnham, Denis

    2006-01-01

    Over half the world's population speaks a tone language, yet infant speech perception research has typically focused on consonants and vowels. Very young infants can discriminate a wide range of native and nonnative consonants and vowels, and then in a process of "perceptual reorganization" over the 1st year, discrimination of most nonnative…

  11. Is Statistical Learning Constrained by Lower Level Perceptual Organization?

    ERIC Educational Resources Information Center

    Emberson, Lauren L.; Liu, Ran; Zevin, Jason D.

    2013-01-01

    In order for statistical information to aid in complex developmental processes such as language acquisition, learning from higher-order statistics (e.g. across successive syllables in a speech stream to support segmentation) must be possible while perceptual abilities (e.g. speech categorization) are still developing. The current study examines…

  12. Different Approaches to the Study of Early Perceptual Learning

    ERIC Educational Resources Information Center

    Bhatt, Ramesh S.; Quinn, Paul C.

    2011-01-01

    Bhatt and Quinn (2011) review evidence indicating that learning plays a powerful role in the development of perceptual organization, and provide a theoretical framework for studying this process. The fact that prominent researchers in diverse areas of cognitive development and adult cognition have commented on this paper (Aslin, 2011; Goldstone,…

  13. Perceptual Learning Style Preferences among Iranian Graduate Students

    ERIC Educational Resources Information Center

    Naserieh, Farid; Sarab, Mohammad Reza Anani

    2013-01-01

    Research suggests that a host of cognitive, affective, and perceptual variables are at work when individuals go about the task of second or foreign language learning. Among these variables are learning styles that are habitual ways of perceiving, processing, and storing information. This study was conducted as a response to Isemonger and…

  14. Reading Multimodal Texts: Perceptual, Structural and Ideological Perspectives

    ERIC Educational Resources Information Center

    Serafini, Frank

    2010-01-01

    This article presents a tripartite framework for analyzing multimodal texts. The three analytical perspectives presented include: (1) perceptual, (2) structural, and (3) ideological analytical processes. Using Anthony Browne's picturebook "Piggybook" as an example, assertions are made regarding what each analytical perspective brings to the…

  15. Perceptual and cognitive spatial learning.

    PubMed

    Bedford, F L

    1993-06-01

    Ss were taught novel mappings between visual space and motor space with either a variant on a prism adaptation paradigm (Experiments 1 and 2) or a nonperceptual cognitive task (Experiments 3 and 4). First, discrimination training specified that 1 visual location required a new pointing response but another location did not. This led to unusual generalization unlike typical generalization decrement. Second, training at 9 locations specified that 1 location required a new response but that the remaining 8 did not. This simple isolation mapping was unlearnable and instead a flat function fit through all of space. In contrast, for the cognitive paradigm, not only was isolation of one region of space easily learned, it was the preferred pattern of generalization. Implications for perceptual learning, as well as the qualitative distinctions between perceptual and cognitive learning, are discussed.

  16. The "Perceptual Wedge Hypothesis" as the Basis for Bilingual Babies' Phonetic Processing Advantage: New insights from fNIRS Brain Imaging

    ERIC Educational Resources Information Center

    Petitto, L. A.; Berens, M. S.; Kovelman, I.; Dubins, M. H.; Jasinska, K.; Shalinsky, M.

    2012-01-01

    In a neuroimaging study focusing on young bilinguals, we explored the brains of bilingual and monolingual babies across two age groups (younger 4-6 months, older 10-12 months), using fNIRS in a new event-related design, as babies processed linguistic phonetic (Native English, Non-Native Hindi) and nonlinguistic Tone stimuli. We found that phonetic…

  17. Toward a Perceptual-Span Theory of Distributed Processing in Reading: A Reply to Rayner, Pollatsek, Drieghe, Slattery, and Reichle (2007)

    ERIC Educational Resources Information Center

    Kliegl, Reinhold

    2007-01-01

    K. Rayner, A. Pollatsek, D. Drieghe, T. J. Slattery, and E. D. Reichle argued that the R. Kliegl, A. Nuthmann, and R. Engbert corpus-analytic evidence for distributed processing during reading should not be accepted because (a) there might be problems of multicollinearity, (b) the distinction between content and function words and the skipping…

  18. To What Extent Do We Hear Phonemic Contrasts in a Non-Native Regional Variety? Tracking the Dynamics of Perceptual Processing with EEG

    ERIC Educational Resources Information Center

    Dufour, Sophie; Brunelliere, Angele; Nguyen, Noel

    2013-01-01

    This combined ERP and behavioral experiment explores the dynamics of processing during the discrimination of vowels in a non-native regional variety. Southern listeners were presented with three word forms, two of which are encountered in both Standard and Southern French ([kot] and [kut]), whereas the third one exists in Standard but not Southern…

  19. Minimalist Approach to Perceptual Interactions

    PubMed Central

    Lenay, Charles; Stewart, John

    2012-01-01

    Work aimed at studying social cognition in an interactionist perspective often encounters substantial theoretical and methodological difficulties: identifying the significant behavioral variables; recording them without disturbing the interaction; and distinguishing between: (a) the necessary and sufficient contributions of each individual partner for a collective dynamics to emerge; (b) features which derive from this collective dynamics and escape from the control of the individual partners; and (c) the phenomena arising from this collective dynamics which are subsequently appropriated and used by the partners. We propose a minimalist experimental paradigm as a basis for this conceptual discussion: by reducing the sensory inputs to a strict minimum, we force a spatial and temporal deployment of the perceptual activities, which makes it possible to obtain a complete recording and control of the dynamics of interaction. After presenting the principles of this minimalist approach to perception, we describe a series of experiments on two major questions in social cognition: recognizing the presence of another intentional subject; and phenomena of imitation. In both cases, we propose explanatory schema which render an interactionist approach to social cognition clear and explicit. Starting from our earlier work on perceptual crossing we present a new experiment on the mechanisms of reciprocal recognition of the perceptual intentionality of the other subject: the emergent collective dynamics of the perceptual crossing can be appropriated by each subject. We then present an experimental study of opaque imitation (when the subjects cannot see what they themselves are doing). This study makes it possible to characterize what a properly interactionist approach to imitation might be. In conclusion, we draw on these results, to show how an interactionist approach can contribute to a fully social approach to social cognition. PMID:22582041

  20. Microbiota Dynamics and Diversity at Different Stages of Industrial Processing of Cocoa Beans into Cocoa Powder

    PubMed Central

    Lima, Lídia J. R.; van der Velpen, Vera; Wolkers-Rooijackers, Judith; Kamphuis, Henri J.; Nout, M. J. Rob

    2012-01-01

    We sampled a cocoa powder production line to investigate the impact of processing on the microbial community size and diversity at different stages. Classical microbiological methods were combined with 16S rRNA gene PCR-denaturing gradient gel electrophoresis, coupled with clone library construction, to analyze the samples. Aerobic thermoresistant spores (ThrS) (100°C; 10 min) were also isolated and characterized (identity, genetic diversity, and spore heat resistance), in view of their relevance to the quality of downstream heat-treated cocoa-flavored drinks. In the nibs (broken, shelled cocoa beans), average levels of total aerobic microorganisms (TAM) (4.4 to 5.6 log CFU/g) and aerobic total spores (TS) (80°C; 10 min; 4.3 to 5.5 log CFU/g) were significantly reduced (P < 0.05) as a result of alkalizing, while fungi (4.2 to 4.4 log CFU/g) and Enterobacteriaceae (1.7 to 2.8 log CFU/g) were inactivated to levels below the detection limit, remaining undetectable throughout processing. Roasting further decreased the levels of TAM and TS, but they increased slightly during subsequent processing. Molecular characterization of bacterial communities based on enriched cocoa samples revealed a predominance of members of the Bacillaceae, Pseudomonadaceae, and Enterococcaceae. Eleven species of ThrS were found, but Bacillus licheniformis and the Bacillus subtilis complex were prominent and revealed great genetic heterogeneity. We concluded that the microbiota of cocoa powder resulted from microorganisms that could have been initially present in the nibs, as well as microorganisms that originated during processing. B. subtilis complex members, particularly B. subtilis subsp. subtilis, formed the most heat-resistant spores. Their occurrence in cocoa powder needs to be considered to ensure the stability of derived products, such as ultrahigh-temperature-treated chocolate drinks. PMID:22327588

  1. Blue-Black or White-Gold? Early Stage Processing and the Color of 'The Dress'

    PubMed Central

    Rabin, Jeff

    2016-01-01

    Purpose In Feb 2015 an image of a dress posted on Tumblr triggered an internet phenomenon: Is the Dress blue and black (BB) or white and gold (WG)? Many claim BB and others insist WG while the true colors are BB. The prevailing theory is that assumptions about the illuminant govern perception of the Dress with WG due to bluish lighting and BB due to yellowish. Our purpose was to determine if early stage optical, retinal and/or neural factors also impact perception of the Dress. Methods Thirty-nine subjects were categorized as BB or WG based on their initial perception of the Dress and their perception reported when viewing the Dress on iPhone 5, iPad, and 22” LCD displays. Macular pigment optical density (MPOD) measured with the QuantifEye™ MPS II and visual brainwaves (VEPs) in response to brief presentations of a transparency of the Dress illuminated by a flashing light were measured on each subject and compared between BB and WG groups. Additionally, CIE chromaticity (color) and luminance (brightness) were measured from multiple areas of the Dress image to determine cone stimulation and contrast. Results Mean MPOD was higher in the WG group (0.49) vs. the BB (0.41, p = 0.04) and median values were higher as well (WG = 0.46, BB = 0.36, p = 0.03). There was no difference in VEP amplitude between groups (p > 0.85) but mean VEP latency was longer in WG (130 msec.) vs. the BB group (107 msec., p = 0.0005). Colorimetry of the Dress showed significantly greater stimulation of blue cones (contrast = 73%) vs. red and green sensitive cones (contrast = 13%). Conclusions Our findings indicate that observers with denser MPOD may be predisposed to perceive the Dress as WG due to great absorption of blue light by the macular pigment. Moreover, the novel, substantial stimulation of blue cones by the Dress may contribute to ambiguity and dichotomous perception since the blue cones are so sparse in the retina. Finally, the delayed WG VEPs indicate distinct neural processing

  2. Differences in early and late stages of information processing between slow versus fast participants.

    PubMed

    Portella, Claudio; Machado, Sergio; Paes, Flávia; Cagy, Mauricio; Sack, Alexander T; Sandoval-Carrillo, Ada; Salas-Pacheco, Jose; Silva, Adriana Cardoso; Piedade, Roberto; Ribeiro, Pedro; Nardi, Antonio Egídio; Arias-Carrión, Oscar

    2014-01-01

    The human brain is a system consisting of various interconnected neural networks, with functional specialization coexisting with functional integration occurring both; temporally and spatially at many levels. The current study ranked and compared fast and slow participants in processing information by assessing latency and amplitude of early and late Event-Related Potential (ERP) components, including P200, N200, Premotor Potential (PMP) and P300. In addition, the Reaction Time (RT) of participants was compared and related to the respective ERP components. For this purpose, twenty right-handed and healthy individuals were subjected to a classical ERP "Oddball" paradigm. Principal Component Analysis (PCA) and Discriminant Function analyses (DFA) used PRE components and the Reaction Time (RT) to classify individuals. Our results indicate that latencies of P200 (O2 electrode), N200 (O2), PMP (C3) and P300 (Pz) components are significantly reduced in the group of fast responding participants. In addition, the P200 amplitude is significantly increased in the group of fast responding participants. Based on these findings, we suggest that the ERP is able to detect even minimal impairments, in the processing of somatosensory information and cognitive and motor stages. Hence, the study of ERP might also be capable of assessing sensorimotor dysfunctions in healthy old-aged people and in neuropsychiatric patients (suffering from dementia, Parkinson's disease, and other neurological disorders). PMID:25838842

  3. Removal of PPCPs from the sludge supernatant in a one stage nitritation/anammox process.

    PubMed

    Alvarino, T; Suarez, S; Katsou, E; Vazquez-Padin, J; Lema, J M; Omil, F

    2015-01-01

    Pharmaceutical and personal care products (PPCPs) are extensively used and can therefore find their way into surface, groundwater and municipal and industrial effluents. In this work, the occurrence, fate and removal mechanisms of 19 selected PPCPs was investigated in an 'ELiminación Autótrofa de Nitrógeno' (ELAN) reactor of 200 L. In this configuration, ammonium oxidation to nitrite and the anoxic ammonium oxidation (anammox)processes occur simultaneously in a single-stage reactor under oxygen limited conditions. The ELAN process achieved high removal (>80%) of the studied hormones, naproxen, ibuprofen, bisphenol A and celestolide, while it was not effective in the removal of carbamazepine (<7%), diazepam (<7%) and fluoxetine (<30%). Biodegradation was the dominant removal mechanism, while sorption was only observed for musk fragrances, fluoxetine and triclosan. The sorption was strongly dependent on the granule size, with smaller granules facilitating the sorption of the target compounds. Increased hydraulic retention time enhanced the intramolecular diffusion of the PPCPs into the granules, and thus increased the solid phase concentration. The increase of nitritation rate favored the removal of ibuprofen, bisphenol A and triclosan, while the removal of erythromycin was strongly correlated to the anammox reaction rate.

  4. Enhanced brainstem encoding predicts musicians’ perceptual advantages with pitch

    PubMed Central

    Bidelman, Gavin M.; Krishnan, Ananthanarayan; Gandour, Jackson T.

    2010-01-01

    Important to Western tonal music is the relationship between pitches both within and between musical chords; melody and harmony are generated by combining pitches selected from the fixed hierarchical scales of music. It is of critical importance that musicians have the ability to detect and discriminate minute deviations in pitch in order to remain in tune with other members of their ensemble. Event-related potentials indicate that cortical mechanisms responsible for detecting mistuning and violations in pitch are more sensitive and accurate in musicians as compared to non-musicians. The aim of the present study was to address whether this superiority is also present at a subcortical stage of pitch processing. Brainstem frequency-following responses (FFRs) were recorded from musicians and non-musicians in response to tuned (i.e., major and minor) and detuned (±4% difference in frequency) chordal arpeggios differing only in the pitch of their third. Results showed that musicians had faster neural synchronization and stronger brainstem encoding for defining characteristics of musical sequences regardless of whether they were in or out of tune. In contrast, non-musicians had relatively strong representation for major/minor chords but showed diminished responses for detuned chords. The close correspondence between the magnitude of brainstem responses and performance on two behavioral pitch discrimination tasks supports the idea that musicians’ enhanced detection of chordal mistuning may be rooted at pre-attentive, sensory stages of processing. Findings suggest that perceptually salient aspects of musical pitch are not only represented at subcortical levels but that these representations are also enhanced by musical experience. PMID:21198980

  5. [Neural correlates of perceptual decisions: the role of the ventral premotor cortex].

    PubMed

    Pardo-Vázquez, José L; Acuña, Carlos

    2014-05-01

    Although the premotor cortex was initially viewed as the substrate of pure motor functions, it was soon realized that this cortical region is also involved in higher order cognitive processes. By using behavioral tasks together with electrophysiological recordings it has been possible to advance in our understanding on the functional role of this area. Given its pattern of connections, the premotor ventral cortex is well suited to participate in perceptual decisions, in which sensory information is combined with knowledge on previous outcomes and expectancies to reach a behavioral choice. The neuronal correlates of the decision process have been described in several cortical areas of primates. In this work we describe our experimental results showing that different stages or elements of perceptual decisions are encoded in the firing rate of premotor ventral cortex neurons. This provides compelling evidence suggesting that this area is involved in the use of sensory evidence -maintained in working memory or retrieved from long-term memory- to reach a decision. Furthermore, after the behavioral response the same neurons convey all the information needed to evaluate the outcome of the choice. This suggests that the premotor ventral cortex could participate in shaping future behavior as a result of this evaluation.

  6. General perceptual contributions to lexical tone normalization.

    PubMed

    Huang, Jingyuan; Holt, Lori L

    2009-06-01

    Within tone languages that use pitch variations to contrast meaning, large variability exists in the pitches produced by different speakers. Context-dependent perception may help to resolve this perceptual challenge. However, whether speakers rely on context in contour tone perception is unclear; previous studies have produced inconsistent results. The present study aimed to provide an unambiguous test of the effect of context on contour lexical tone perception and to explore its underlying mechanisms. In three experiments, Mandarin listeners' perception of Mandarin first and second (high-level and mid-rising) tones was investigated with preceding speech and non-speech contexts. Results indicate that the mean fundamental frequency (f0) of a preceding sentence affects perception of contour lexical tones and the effect is contrastive. Following a sentence with a higher-frequency mean f0, the following syllable is more likely to be perceived as a lower frequency lexical tone and vice versa. Moreover, non-speech precursors modeling the mean spectrum of f0 also elicit this effect, suggesting general perceptual processing rather than articulatory-based or speaker-identity-driven mechanisms. PMID:19507980

  7. Where's Waldo? How perceptual, cognitive, and emotional brain processes cooperate during learning to categorize and find desired objects in a cluttered scene.

    PubMed

    Chang, Hung-Cheng; Grossberg, Stephen; Cao, Yongqiang

    2014-01-01

    The Where's Waldo problem concerns how individuals can rapidly learn to search a scene to detect, attend, recognize, and look at a valued target object in it. This article develops the ARTSCAN Search neural model to clarify how brain mechanisms across the What and Where cortical streams are coordinated to solve the Where's Waldo problem. The What stream learns positionally-invariant object representations, whereas the Where stream controls positionally-selective spatial and action representations. The model overcomes deficiencies of these computationally complementary properties through What and Where stream interactions. Where stream processes of spatial attention and predictive eye movement control modulate What stream processes whereby multiple view- and positionally-specific object categories are learned and associatively linked to view- and positionally-invariant object categories through bottom-up and attentive top-down interactions. Gain fields control the coordinate transformations that enable spatial attention and predictive eye movements to carry out this role. What stream cognitive-emotional learning processes enable the focusing of motivated attention upon the invariant object categories of desired objects. What stream cognitive names or motivational drives can prime a view- and positionally-invariant object category of a desired target object. A volitional signal can convert these primes into top-down activations that can, in turn, prime What stream view- and positionally-specific categories. When it also receives bottom-up activation from a target, such a positionally-specific category can cause an attentional shift in the Where stream to the positional representation of the target, and an eye movement can then be elicited to foveate it. These processes describe interactions among brain regions that include visual cortex, parietal cortex, inferotemporal cortex, prefrontal cortex (PFC), amygdala, basal ganglia (BG), and superior colliculus (SC). PMID

  8. Can theories of animal discrimination explain perceptual learning in humans?

    PubMed

    Mitchell, Chris; Hall, Geoffrey

    2014-01-01

    We present a review of recent studies of perceptual learning conducted with nonhuman animals. The focus of this research has been to elucidate the mechanisms by which mere exposure to a pair of similar stimuli can increase the ease with which those stimuli are discriminated. These studies establish an important role for 2 mechanisms, one involving inhibitory associations between the unique features of the stimuli, the other involving a long-term habituation process that enhances the relative salience of these features. We then examine recent work investigating equivalent perceptual learning procedures with human participants. Our aim is to determine the extent to which the phenomena exhibited by people are susceptible to explanation in terms of the mechanisms revealed by the animal studies. Although we find no evidence that associative inhibition contributes to the perceptual learning effect in humans, initial detection of unique features (those that allow discrimination between 2 similar stimuli) appears to depend on an habituation process. Once the unique features have been detected, a tendency to attend to those features and to learn about their properties enhances subsequent discrimination. We conclude that the effects obtained with humans engage mechanisms additional to those seen in animals but argue that, for the most part, these have their basis in learning processes that are common to animals and people. In a final section, we discuss some implications of this analysis of perceptual learning for other aspects of experimental psychology and consider some potential applications.

  9. Perceptual anomalies in schizophrenia: integrating phenomenology and cognitive neuroscience.

    PubMed

    Uhlhaas, Peter J; Mishara, Aaron L

    2007-01-01

    From phenomenological and experimental perspectives, research in schizophrenia has emphasized deficits in "higher" cognitive functions, including attention, executive function, as well as memory. In contrast, general consensus has viewed dysfunctions in basic perceptual processes to be relatively unimportant in the explanation of more complex aspects of the disorder, including changes in self-experience and the development of symptoms such as delusions. We present evidence from phenomenology and cognitive neuroscience that changes in the perceptual field in schizophrenia may represent a core impairment. After introducing the phenomenological approach to perception (Husserl, the Gestalt School), we discuss the views of Paul Matussek, Klaus Conrad, Ludwig Binswanger, and Wolfgang Blankenburg on perception in schizophrenia. These 4 psychiatrists describe changes in perception and automatic processes that are related to the altered experience of self. The altered self-experience, in turn, may be responsible for the emergence of delusions. The phenomenological data are compatible with current research that conceptualizes dysfunctions in perceptual processing as a deficit in the ability to combine stimulus elements into coherent object representations. Relationships of deficits in perceptual organization to cognitive and social dysfunction as well as the possible neurobiological mechanisms are discussed.

  10. Perceptual learning of degraded speech by minimizing prediction error.

    PubMed

    Sohoglu, Ediz; Davis, Matthew H

    2016-03-22

    Human perception is shaped by past experience on multiple timescales. Sudden and dramatic changes in perception occur when prior knowledge or expectations match stimulus content. These immediate effects contrast with the longer-term, more gradual improvements that are characteristic of perceptual learning. Despite extensive investigation of these two experience-dependent phenomena, there is considerable debate about whether they result from common or dissociable neural mechanisms. Here we test single- and dual-mechanism accounts of experience-dependent changes in perception using concurrent magnetoencephalographic and EEG recordings of neural responses evoked by degraded speech. When speech clarity was enhanced by prior knowledge obtained from matching text, we observed reduced neural activity in a peri-auditory region of the superior temporal gyrus (STG). Critically, longer-term improvements in the accuracy of speech recognition following perceptual learning resulted in reduced activity in a nearly identical STG region. Moreover, short-term neural changes caused by prior knowledge and longer-term neural changes arising from perceptual learning were correlated across subjects with the magnitude of learning-induced changes in recognition accuracy. These experience-dependent effects on neural processing could be dissociated from the neural effect of hearing physically clearer speech, which similarly enhanced perception but increased rather than decreased STG responses. Hence, the observed neural effects of prior knowledge and perceptual learning cannot be attributed to epiphenomenal changes in listening effort that accompany enhanced perception. Instead, our results support a predictive coding account of speech perception; computational simulations show how a single mechanism, minimization of prediction error, can drive immediate perceptual effects of prior knowledge and longer-term perceptual learning of degraded speech. PMID:26957596

  11. Perceptual learning of degraded speech by minimizing prediction error

    PubMed Central

    Sohoglu, Ediz

    2016-01-01

    Human perception is shaped by past experience on multiple timescales. Sudden and dramatic changes in perception occur when prior knowledge or expectations match stimulus content. These immediate effects contrast with the longer-term, more gradual improvements that are characteristic of perceptual learning. Despite extensive investigation of these two experience-dependent phenomena, there is considerable debate about whether they result from common or dissociable neural mechanisms. Here we test single- and dual-mechanism accounts of experience-dependent changes in perception using concurrent magnetoencephalographic and EEG recordings of neural responses evoked by degraded speech. When speech clarity was enhanced by prior knowledge obtained from matching text, we observed reduced neural activity in a peri-auditory region of the superior temporal gyrus (STG). Critically, longer-term improvements in the accuracy of speech recognition following perceptual learning resulted in reduced activity in a nearly identical STG region. Moreover, short-term neural changes caused by prior knowledge and longer-term neural changes arising from perceptual learning were correlated across subjects with the magnitude of learning-induced changes in recognition accuracy. These experience-dependent effects on neural processing could be dissociated from the neural effect of hearing physically clearer speech, which similarly enhanced perception but increased rather than decreased STG responses. Hence, the observed neural effects of prior knowledge and perceptual learning cannot be attributed to epiphenomenal changes in listening effort that accompany enhanced perception. Instead, our results support a predictive coding account of speech perception; computational simulations show how a single mechanism, minimization of prediction error, can drive immediate perceptual effects of prior knowledge and longer-term perceptual learning of degraded speech. PMID:26957596

  12. Perceptual learning of degraded speech by minimizing prediction error.

    PubMed

    Sohoglu, Ediz; Davis, Matthew H

    2016-03-22

    Human perception is shaped by past experience on multiple timescales. Sudden and dramatic changes in perception occur when prior knowledge or expectations match stimulus content. These immediate effects contrast with the longer-term, more gradual improvements that are characteristic of perceptual learning. Despite extensive investigation of these two experience-dependent phenomena, there is considerable debate about whether they result from common or dissociable neural mechanisms. Here we test single- and dual-mechanism accounts of experience-dependent changes in perception using concurrent magnetoencephalographic and EEG recordings of neural responses evoked by degraded speech. When speech clarity was enhanced by prior knowledge obtained from matching text, we observed reduced neural activity in a peri-auditory region of the superior temporal gyrus (STG). Critically, longer-term improvements in the accuracy of speech recognition following perceptual learning resulted in reduced activity in a nearly identical STG region. Moreover, short-term neural changes caused by prior knowledge and longer-term neural changes arising from perceptual learning were correlated across subjects with the magnitude of learning-induced changes in recognition accuracy. These experience-dependent effects on neural processing could be dissociated from the neural effect of hearing physically clearer speech, which similarly enhanced perception but increased rather than decreased STG responses. Hence, the observed neural effects of prior knowledge and perceptual learning cannot be attributed to epiphenomenal changes in listening effort that accompany enhanced perception. Instead, our results support a predictive coding account of speech perception; computational simulations show how a single mechanism, minimization of prediction error, can drive immediate perceptual effects of prior knowledge and longer-term perceptual learning of degraded speech.

  13. Spectroscopic determination of metals in palm oils from different stages of the technological process.

    PubMed

    Szydłowska-Czerniak, Aleksandra; Trokowski, Konrad; Karlovits, György; Szłyk, Edward

    2013-03-01

    Magnesium, calcium, copper, iron, and lead in palm oils ( Elaeis guineensis ) at various stages of the refining process were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion. The mean concentrations of Mg, Ca, Cu, Fe, and Pb in the studied palm oils varied from 20.7 to 7090.1 μg kg(-1), from 193.9 to 8077.9 μg kg(-1), from 29.7 to 463.0 μg kg(-1), from 115.2 to 415.9 μg kg(-1), and from 1.7 to 16.0 μg kg(-1), respectively, which are below the Polish legal requirements. The comparable precisions for the proposed ICP-MS (RSD = 0.81-5.99%) and standard GFAAS (RSD = 1.18-5.26%) methods demonstrate the benefit of the ICP-MS method in the routine analysis of metal ions in palm oils. There are significant, positive correlations between Ca and Mg, between Ca and Cu, between Fe and Pb, between Cu and Fe, between Cu and Mg, and between Cu and Pb in palm oils determined by two analytical methods (r = 0.8798-0.9817, p < 0.05). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used for discrimination of the quality of the analyzed palm oils based on main and trace metal contents determined by the proposed ICP-MS and the standard GFAAS methods. Two main groups were identified by HCA, whereas the classification and characterization of the studied palm oils within each of groups on the basis of metal ions amounts were obtained from PCA. The chemometric analyses demonstrated that crude palm oil had the highest level of the determined metals concentrations. Also, the analyzed metals in palm oils from different steps of the refining process were grouped using HCA to assess the effectiveness of technological processes for their removal. PMID:23394464

  14. The separation of processing stages in a lexical interference fMRI-paradigm.

    PubMed

    Abel, Stefanie; Dressel, Katharina; Bitzer, Ruth; Kümmerer, Dorothee; Mader, Irina; Weiller, Cornelius; Huber, Walter

    2009-02-01

    In picture-word interference paradigms, the picture naming process is influenced by an additional presentation of linguistic distractors. Naming response times (RTs) are speeded (facilitation) by associatively-related and phonologically-related words when compared to unrelated words, while they are slowed down by categorically-related words (inhibition), given that distractor onsets occur at appropriate stimulus onset asynchronies (SOAs). In the present study with healthy subjects, we for the first time integrated all four auditorily presented distractor types into a single paradigm at an SOA of -200 ms, in order to directly compare behavioral and neural interference effects between them. The behavioral study corroborated results of previous studies and revealed that associatively-related distractors speeded RTs even more than phonologically-related distractors, thereby becoming equally fast as naming without distractors. Distractors were assumed to specifically enhance activation of brain areas corresponding to processing stages as determined in a cognitive model of word production (Indefrey, P., Levelt, W.J.M., 2004. The spatial and temporal signatures of word production components. Cognition 92, 101-144.). Functional magnetic resonance imaging (fMRI) at 3 T revealed activation of left superior temporal gyrus exclusively for phonologically-related distractors, and activation of left or right lingual gyrus exclusively for associatively-related and categorically-related distractors, respectively. Moreover, phonologically-related distractors elicited phonological-phonetic networks, and both semantic distractors evoked areas associated with mental imagery, semantics, and episodic memory retrieval and associations. While processes involved in distractor inhibition (e.g., conflict/competition monitoring) and high articulatory demands were observed for categorically-related distractors, priming of articulatory planning was revealed for associatively-related distractors

  15. Salmonella spp. and hygiene indicator microorganisms in chicken carcasses obtained at different processing stages in two slaughterhouses.

    PubMed

    Matias, Beatriz Garbelotti; Pinto, Paulo Sérgio de Arruda; Cossi, Marcus Vinícius Coutinho; Nero, Luís Augusto

    2010-03-01

    Chicken meat is considered an important vehicle of foodborne pathogens such as Salmonella spp., demanding an effective control of its contamination during industrial processing. This study aimed to investigate the presence of Salmonella spp. and microbiological indicators at different stages of processing in two slaughterhouses (Sh1, high-capacity; Sh2, low-capacity). Surface samples of chicken carcasses were collected in the following sequential stages: (A) immediately before evisceration, (B) after evisceration, (C) after showering, and (D) after chiller. All samples were submitted for detection of Salmonella spp. and enumeration of mesophilic aerobes, total coliforms, thermotolerant coliforms, and Escherichia coli. The obtained means and frequencies were compared by analysis of variance and chi-square tests (p < 0.05), considering different slaughterhouses and stages of processing. No significant differences were observed between the frequencies of Salmonella spp. obtained at different steps in Sh1 and Sh2 (p > 0.05). Sh2 showed higher levels of microbiological contamination when compared with Sh1 for mesophilic aerobes (in stages B and D), total coliforms and thermotolerant coliforms (stage D), and E. coli (all stages) (p < 0.05). The variation in the levels of contamination by microbiological indicators over the processing indicated the significance of different control procedures adopted by slaughterhouses for the microbiological quality of chicken carcasses.

  16. Biomass waste gasification - Can be the two stage process suitable for tar reduction and power generation?

    SciTech Connect

    Sulc, Jindrich; Stojdl, Jiri; Richter, Miroslav; Popelka, Jan; Svoboda, Karel; Smetana, Jiri; Vacek, Jiri; Skoblja, Siarhei; Buryan, Petr

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Comparison of one stage (co-current) and two stage gasification of wood pellets. Black-Right-Pointing-Pointer Original arrangement with grate-less reactor and upward moving bed of the pellets. Black-Right-Pointing-Pointer Two stage gasification leads to drastic reduction of tar content in gas. Black-Right-Pointing-Pointer One stage gasification produces gas with higher LHV at lower overall ER. Black-Right-Pointing-Pointer Content of ammonia in gas is lower in two stage moving bed gasification. - Abstract: A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kW{sub th}. The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950 Degree-Sign C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar

  17. Effects of load and maintenance duration on the time course of information encoding and retrieval in working memory: from perceptual analysis to post-categorization processes

    PubMed Central

    Pinal, Diego; Zurrón, Montserrat; Díaz, Fernando

    2014-01-01

    Working memory (WM) involves three cognitive events: information encoding, maintenance, and retrieval; these are supported by brain activity in a network of frontal, parietal and temporal regions. Manipulation of WM load and duration of the maintenance period can modulate this activity. Although such modulations have been widely studied using the event-related potentials (ERP) technique, a precise description of the time course of brain activity during encoding and retrieval is still required. Here, we used this technique and principal component analysis to assess the time course of brain activity during encoding and retrieval in a delayed match to sample task. We also investigated the effects of memory load and duration of the maintenance period on ERP activity. Brain activity was similar during information encoding and retrieval and comprised six temporal factors, which closely matched the latency and scalp distribution of some ERP components: P1, N1, P2, N2, P300, and a slow wave. Changes in memory load modulated task performance and yielded variations in frontal lobe activation. Moreover, the P300 amplitude was smaller in the high than in the low load condition during encoding and retrieval. Conversely, the slow wave amplitude was higher in the high than in the low load condition during encoding, and the same was true for the N2 amplitude during retrieval. Thus, during encoding, memory load appears to modulate the processing resources for context updating and post-categorization processes, and during retrieval it modulates resources for stimulus classification and context updating. Besides, despite the lack of differences in task performance related to duration of the maintenance period, larger N2 amplitude and stronger activation of the left temporal lobe after long than after short maintenance periods were found during information retrieval. Thus, results regarding the duration of maintenance period were complex, and future work is required to test the time

  18. Additive Factors Do Not Imply Discrete Processing Stages: A Worked Example Using Models of the Stroop Task

    PubMed Central

    Stafford, Tom; Gurney, Kevin N.

    2011-01-01

    Previously, it has been shown experimentally that the psychophysical law known as Piéron’s Law holds for color intensity and that the size of the effect is additive with that of Stroop condition (Stafford et al., 2011). According to the additive factors method (Donders, 1868–1869/1969; Sternberg, 1998), additivity is assumed to indicate independent and discrete processing stages. We present computational modeling work, using an existing Parallel Distributed Processing model of the Stroop task (Cohen et al., 1990) and a standard model of decision making (Ratcliff, 1978). This demonstrates that additive factors can be successfully accounted for by existing single stage models of the Stroop effect. Consequently, it is not valid to infer either discrete stages or separate loci of effects from additive factors. Further, our modeling work suggests that information binding may be a more important architectural property for producing additive factors than discrete stages. PMID:22102842

  19. Perceptual task induces saccadic adaptation by target selection.

    PubMed

    Schütz, Alexander C; Souto, David

    2015-01-01

    Adaptation of saccades can be induced by different error signals, such as retinal position errors, prediction errors, or reinforcement learning. Recently, we showed that a shift in the spatial goal of a perceptual task can induce saccadic adaptation, in the absence of a bottom-up position error. Here, we investigated whether this top-down effect is mediated by the visibility of the task-relevant object, by reinforcement due to the feedback about the perceptual judgment or by a target selection mechanism. Participants were asked to discriminate visual stimuli arranged in a vertical compound. To induce adaptation, the discrimination target was presented at eccentric locations in the compound. In the first experiment, we compared adaptation with an easy and difficult discrimination. In the second experiment, we compared adaptation when feedback about the perceptual task was valid and when feedback was provided but was unrelated to performance. In the third experiment, we compared adaptation with instructions to fixate one of the elements in the compound-target selection-to the perceptual task condition-target selection and discrimination. To control for a bottom-up stimulus effect, we ran a fourth experiment in which the only instruction was to look at the compound. The saccade amplitude data were fitted by a two-state model distinguishing between an immediate and a gradual error correction process. We replicated our finding that a perceptual task can drive adaptation of saccades. Adaptation showed no effect of feedback reliability, nor an effect of the perceptual task beyond target selection. Adaptation was induced by a top-down signal since it was absent when there was no target selection instruction and no perceptual task. The immediate error correction was larger for the difficult than for the easy condition, suggesting that task difficulty affects mainly voluntary saccade targeting. In addition, the repetition of experiments one week later increased the magnitude

  20. Simulation of the Two Stages Stretch-Blow Molding Process: Infrared Heating and Blowing Modeling

    SciTech Connect

    Bordival, M.; Schmidt, F. M.; Le Maoult, Y.; Velay, V.

    2007-05-17

    In the Stretch-Blow Molding (SBM) process, the temperature distribution of the reheated perform affects drastically the blowing kinematic, the bottle thickness distribution, as well as the orientation induced by stretching. Consequently, mechanical and optical properties of the final bottle are closely related to heating conditions. In order to predict the 3D temperature distribution of a rotating preform, numerical software using control-volume method has been developed. Since PET behaves like a semi-transparent medium, the radiative flux absorption was computed using Beer Lambert law. In a second step, 2D axi-symmetric simulations of the SBM have been developed using the finite element package ABAQUS registered . Temperature profiles through the preform wall thickness and along its length were computed and applied as initial condition. Air pressure inside the preform was not considered as an input variable, but was automatically computed using a thermodynamic model. The heat transfer coefficient applied between the mold and the polymer was also measured. Finally, the G'sell law was used for modeling PET behavior. For both heating and blowing stage simulations, a good agreement has been observed with experimental measurements. This work is part of the European project ''APT{sub P}ACK'' (Advanced knowledge of Polymer deformation for Tomorrow's PACKaging)

  1. Toward a transtheoretical model of interprofessional education: stages, processes and forces supporting institutional change.

    PubMed

    Clark, Phillip G

    2013-01-01

    The history of interprofessional education (IPE) in the USA is a checkered one, characterized by boom and bust cycles of advancement and retrenchment, expansion and contraction. The successful development, implementation and continuation of IPE in health and social care in US higher education institutions all depend on a number of factors related to how individuals and organizations do or do not support it in the academic setting. Deliberate and planned change to advance IPE requires a comprehensive theoretical framework to guide it and insure its success. A transtheoretical model (TTM) of institutional change is proposed as a comprehensive framework of the stages, processes and forces that can facilitate and maintain change in support of IPE. The TTM framework recognizes the complexity of change, and captures and organizes important elements from different organizational theories. It also provides a structure for conceptualizing the multiple dimensions needed for change, offering intervention strategies and leverage points to be used by leaders in promoting and maintaining it. Finally, the TTM model suggests that the stabilization of IPE programs over the long term is dependent on a real and significant shift in institutional values in response to forces from both within and without the organization.

  2. Situational context is important: perceptual grouping modulates temporal perception.

    PubMed

    Zhou, Bin; Yang, Shaojuan; Zhang, Ting; Zhang, Xin; Mao, Lihua

    2015-09-01

    Subjective time of an event in the sub-second range is often compressed or dilated by the situational context created by preceding and succeeding stimuli. How such context distorts psychological time is still an open question. Here, we pursued this issue by examining whether the perceptual grouping among successive visual stimuli modulates the perceived duration. Using a duration comparison task, we asked observers to judge the relative duration of a target and a comparison item, and estimated the apparent duration of the target from the corresponding psychometric function. The target was temporally flanked by a preceding item and a succeeding item. In different conditions, the target was more similar to either the preceding or the succeeding item. Results showed that perceptual grouping based on similarity modulated perceived duration. Specifically, when the target was grouped with the preceding item, its subjective duration was shorter than when it was grouped with the succeeding item. Interestingly, this pattern was observed when the preceding and target items were kept constant while the succeeding item was manipulated, suggesting that the effect depends, to some degree, on the holistic perceptual grouping rather than on fragmented processes. These results demonstrate that the situational context is an important factor in shaping temporal codes, thus bridging the seemingly independent perceptual feature processes and temporal representation.

  3. Conceptual and perceptual information both influence melody identification.

    PubMed

    Schulkind, Matthew D

    2004-07-01

    Three processes have been identified as central to object identification: top-down processing, bottom-up processing, and lateral competition. Six experiments using the perceptual interference paradigm were conducted to assess the relative contributions of these three processes to melody identification. Significant interference was observed only when the target and the distracting information were difficult to distinguish both perceptually and conceptually. Lateral competition-the activation of specific distractor melodies--did not influence the magnitude of interference observed. These results suggest that bottom-up and top-down processes contribute more to melody identification than does lateral competition. The data are discussed in terms of the broader literature on object identification and the relationship between identifying melodies, spoken words, and visual objects.

  4. Optimizing Linked Perceptual Class Formation and Transfer of Function

    ERIC Educational Resources Information Center

    Fields, Lanny; Garruto, Michelle

    2009-01-01

    A linked perceptual class consists of two distinct perceptual classes, A' and B', the members of which have become related to each other. For example, a linked perceptual class might be composed of many pictures of a woman (one perceptual class) and the sounds of that woman's voice (the other perceptual class). In this case, any sound of the…

  5. Simultaneous Long-term Recordings at Two Neuronal Processing Stages in Behaving Honeybees

    PubMed Central

    Brill, Martin Fritz; Reuter, Maren; Rössler, Wolfgang; Strube-Bloss, Martin Fritz

    2014-01-01

    In both mammals and insects neuronal information is processed in different higher and lower order brain centers. These centers are coupled via convergent and divergent anatomical connections including feed forward and feedback wiring. Furthermore, information of the same origin is partially sent via parallel pathways to different and sometimes into the same brain areas. To understand the evolutionary benefits as well as the computational advantages of these wiring strategies and especially their temporal dependencies on each other, it is necessary to have simultaneous access to single neurons of different tracts or neuropiles in the same preparation at high temporal resolution. Here we concentrate on honeybees by demonstrating a unique extracellular long term access to record multi unit activity at two subsequent neuropiles1, the antennal lobe (AL), the first olfactory processing stage and the mushroom body (MB), a higher order integration center involved in learning and memory formation, or two parallel neuronal tracts2 connecting the AL with the MB. The latter was chosen as an example and will be described in full. In the supporting video the construction and permanent insertion of flexible multi channel wire electrodes is demonstrated. Pairwise differential amplification of the micro wire electrode channels drastically reduces the noise and verifies that the source of the signal is closely related to the position of the electrode tip. The mechanical flexibility of the used wire electrodes allows stable invasive long term recordings over many hours up to days, which is a clear advantage compared to conventional extra and intracellular in vivo recording techniques. PMID:25080029

  6. Coconut water of different maturity stages ameliorates inflammatory processes in model of inflammation

    PubMed Central

    Rao, Sadia Saleem; Najam, Rahila

    2016-01-01

    Aim: Coconut water is a natural beverage that is a part of daily diet of many people. This study was designed to explore the anti-inflammatory activity of coconut water of different maturation stages (young and mature) with rat paw edema model of inflammation using plethysmometer. Methodology: For this study, albino rats were selected and divided into four equal groups (10 rats in each group). Group 1 was set as control and administered distilled water 1 ml orally; Groups 2 and 3 were treated with young and mature coconut water, respectively, at 4 ml/100 g dose orally. Group 4 was treated with the standard drug (ibuprofen) at 400 mg/70 kg. 0.1 ml of 1% w/v acetic acid was administered in the subplantar tissue of rat paw 30 min after oral treatments of groups. Plethysmometer was used to measure rat paw edema. Results: Results revealed that both coconut water possess significant anti-inflammatory activity (P < 0.001). In comparison to control, percent inhibition by young coconut water was 20.22%, 35.13%, 42.52%, and 36% at 1, 2, 3, and 4 h of acetic acid administration, respectively. However, maximum percent inhibition (42.52%) was observed in the second phase of the inflammatory process. On the other hand, percent inhibition by mature coconut water was 18.80%, 25.94%, 24.13%, and 18.66% at 1, 2, 3, and 4 h of acetic acid administration, respectively. However, maximum percent inhibition (25.94%) was observed in the first phase of the inflammatory process. Conclusions: This study strongly suggests the use of young coconut water for potent anti-inflammatory effect and mature coconut water for moderate anti-inflammatory effect. PMID:27366350

  7. Sequential, Multi-stage Processes for Intraplate and Intraslab Seismogenesis in Oceanic Lithosphere

    NASA Astrophysics Data System (ADS)

    Kirby, S. H.

    2011-12-01

    Marine geoscience surveys and thermal modeling have shown that oceanic lithosphere has an extremely complex tenure under the ocean basins and during slab descent involving magmatic, hydrothermal, and tectonic processes, processes that undoubtedly leave a cumulative imprint on plate/slab mineralogy, structure, and fluid makeup. These processes clearly have implications for the physical states of plate materials from ridges to trenches to deep slabs and give insights into the geological and geophysical observables, especially intraplate and intraslab earthquakes. Likely stages of this inheritance include: (1) Shallow melting and stretching deformation at Mid Ocean Ridges (MOR's) produce brittle faulting and earthquakes as well as hydrothermal alteration, segregation into oceanic crust and mantle, and internal plate deformation as indicated by seismic anisotropy. Hydrothermal alteration of faults cutting oceanic crust at MOR's have been posited as possible sources of dehydration fluids or dehydration embrittlement near the original seafloor during subsequent slab descent as an explanation of some intermediate-depth earthquakes. (2) Ocean Island (Plume) Volcanism produce an additional component of magmatic CO2 of deeper origin as well as plate deformation due to mass loading by the island edifices. [Kirby presentation in Session T13, this meeting]. (3) Intraplate deformation especially near triple junctions or other settings where discontinuous lateral boundary stresses propagate into plate interiors. (4) Near-trench deformation associated with plate bending that is expressed by shallow normal-faulting earthquakes, fault scarps on the ocean floor off trenches, and seismic reflections of normal faults, all of which locally indicate that such faulting penetrates well into the lithospheric mantle. It seems likely that even though the thermal conditions in most oceanic plates near trenches are relatively cold, mineral alteration along normal-fault pathways from ingress of

  8. Integrating stage and continuum models to explain processing of exercise messages and exercise initiation among sedentary college students.

    PubMed

    Rosen, C S

    2000-03-01

    Concepts from the transtheoretical model (J.O. Prochaska, C.C. DiClemente, & J.C. Norcross, 1992), theory of planned behavior (I. Ajzen, 1985), and the elaboration likelihood model (R.E. Petty & J.T. Cacioppo, 1986b) were used to examine how exercise readiness impacted processing of exercise messages and exercise initiation. Sedentary college students (n = 147) were assessed for exercise attitude, intent, behavior, and stage of change. Students also listed their thoughts after reading messages with either strong or weak arguments for exercise. Attitude predicted depth of message processing, but stage of change did not. Stage of change and intent at baseline predicted exercise adoption at 1- to 3-month follow-up (n = 134), with baseline activity moderating the effect of intent. Tailoring messages to recipients' depth of processing and interactive effects of intent and behavior on exercise adoption should be considered in future research. PMID:10762101

  9. Brain Network Connectivity During Language Comprehension: Interacting Linguistic and Perceptual Subsystems.

    PubMed

    Fonteneau, Elisabeth; Bozic, Mirjana; Marslen-Wilson, William D

    2015-10-01

    The dynamic neural processes underlying spoken language comprehension require the real-time integration of general perceptual and specialized linguistic information. We recorded combined electro- and magnetoencephalographic measurements of participants listening to spoken words varying in perceptual and linguistic complexity. Combinatorial linguistic complexity processing was consistently localized to left perisylvian cortices, whereas competition-based perceptual complexity triggered distributed activity over both hemispheres. Functional connectivity showed that linguistically complex words engaged a distributed network of oscillations in the gamma band (20-60 Hz), which only partially overlapped with the network supporting perceptual analysis. Both processes enhanced cross-talk between left temporal regions and bilateral pars orbitalis (BA47). The left-lateralized synchrony between temporal regions and pars opercularis (BA44) was specific to the linguistically complex words, suggesting a specific role of left frontotemporal cross-cortical interactions in morphosyntactic computations. Synchronizations in oscillatory dynamics reveal the transient coupling of functional networks that support specific computational processes in language comprehension.

  10. Single-wafer-processed nano-positioning XY-stages with trench-sidewall micromachining technology

    NASA Astrophysics Data System (ADS)

    Gu, Lei; Li, Xinxin; Bao, Haifei; Liu, Bin; Wang, Yuelin; Liu, Min; Yang, Zunxian; Cheng, Baoluo

    2006-07-01

    For operation and manipulation with nanometric positioning precision, a single crystalline silicon micro XY-stage is developed by using double-sided bulk-micromachining technology. Front-side deep reactive ion etching combined with backside anisotropic etching constructs the high-aspect-ratio comb-driven XY-stage in a single standard silicon wafer (i.e., no silicon on insulator wafer is used). For integrating several electrostatic actuators in one silicon chip, different actuators are electrically isolated from each other using a trench-sidewall insulating technique. SiO2-refilled trench bars are formed on vertical trench sidewalls to isolate adjacent comb-drive elements. Combined with the reverse-biased p-n junction along the boron-diffused trench sidewall for comb driving, individual actuators can be operated independently. The developed XY-stage of 1600 × 1600 µm2 is suspended by four sets of folded-beam and bending-flexure composite springs. To maximize the moving distance, a two-segment comb finger with a gently curved transition is used for both improving the actuation efficiency and avoiding side instability of the stage. The experimental results verify the stage design including the gentle transition of a two-segment comb-drive scheme. Under 23 V driving voltage, a 10 µm moving stroke is measured in each of the four directions. Compared with a conventional comb structure, the two-segment comb fingers contribute 70% improvement in actuating amplitude. The positioning precision of the stage is evaluated with a nano-mechanical indenting experiment. A scanning probe microscopy probe with an electrical-heated nano tip is put in contact with the surface of a polymethyl methacrylate film that is coated on the stage surface. Along with the movement of the stage, pulsed heating on the nano tip produces serial nano-pitches. With the nano-indenting experiment, better than 18 nm positioning precision is obtained for the XY-stage.

  11. Biomass waste gasification - can be the two stage process suitable for tar reduction and power generation?

    PubMed

    Sulc, Jindřich; Stojdl, Jiří; Richter, Miroslav; Popelka, Jan; Svoboda, Karel; Smetana, Jiří; Vacek, Jiří; Skoblja, Siarhei; Buryan, Petr

    2012-04-01

    A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kW(th). The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950°C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar compound contents confirmed superiority of the two stage gasification system, drastic decrease of aromatic compounds with two and higher number of benzene rings by 1-2 orders. On the other hand the two stage gasification (with overall ER=0.71) led to substantial reduction of gas heating value (LHV=3.15 MJ/Nm(3)), elevation of gas volume and increase of nitrogen content in fuel gas. The increased temperature (>950°C) at the entrance to the char bed caused also substantial decrease of ammonia content in fuel gas. The char with higher content of ash leaving the

  12. Characteristics of hydrogen and methane production from cornstalks by an augmented two- or three-stage anaerobic fermentation process.

    PubMed

    Lu, Yuan; Lai, Qiheng; Zhang, Chong; Zhao, Hongxin; Ma, Kun; Zhao, Xuebing; Chen, Hongzhang; Liu, Dehua; Xing, Xin-Hui

    2009-06-01

    This paper presents the co-production of hydrogen and methane from cornstalks by a two- or three-stage anaerobic fermentation process augmented with effective artificial microbial community. Two-stage fermentation by using the anaerobic sludge and DGGE analysis showed that effective and stable strains should be introduced into the system. We introduced Enterobacter aerogens or Clostridium paraputrificum into the hydrogen stage, and C. paraputrificum was proven to be more effective. In the three-stage process consisting of the improved hydrolysis, hydrogen and methane production stages, the highest soluble sugars (0.482 kg/kg cornstalks) were obtained after the introduction of Clostridium thermocellum in the hydrolysis stage, under the thermophilic (55 degrees C) and acidic (pH 5.0) conditions. Hydrolysates from 1 kg of cornstalks could produce 2.61 mol (63.7 l) hydrogen by augmentation with C. paraputrificum and 4.69 mol (114.6 l) methane by anaerobic granular sludge, corresponding to 54.1% energy recovery.

  13. Individual differences in the time course of reward processing: Stage-specific links with depression and impulsivity.

    PubMed

    Novak, Brittni K; Novak, Keisha D; Lynam, Donald R; Foti, Dan

    2016-09-01

    Reward dysfunction has been implicated in a wide range of psychological disorders, including internalizing and externalizing psychopathology. Basic neuroscience research has shown that reward is a multistage process, yet it is unclear how specific stages relate to individual differences in reward sensitivity. The current study utilized event-related potentials elicited during a monetary incentive task to parse sub-stages within anticipatory and consummatory reward processing. Effects of depressive symptoms and trait impulsivity were examined at each sub-stage (N=92). Reward anticipation modulated neural activity across three sub-stages: cue detection (cue-P3), approach behavior (contingent negative variation, CNV), and outcome anticipation (stimulus preceding negativity). Reward delivery modulated activity across two sub-stages: initial evaluation (reward positivity, RewP), and allocation of attention (feedback-P3). Sensation seeking predicted faster reaction times, as well as cue-P3 and RewP amplitudes. Depression and lack of premeditation interacted to predict CNV and RewP amplitudes. Results demonstrate that individual differences in reward functioning are stage-specific.

  14. Contextual Valence and Sociality Jointly Influence the Early and Later Stages of Neutral Face Processing

    PubMed Central

    Xu, Mengsi; Li, Zhiai; Diao, Liuting; Fan, Lingxia; Yang, Dong

    2016-01-01

    Recent studies have demonstrated that face perception is influenced by emotional contextual information. However, because facial expressions are routinely decoded and understood during social communication, sociality should also be considered—that is, it seems necessary to explore whether emotional contextual effects are influenced by the sociality of contextual information. Furthermore, although one behavioral study has explored the effects of context on selective attention to faces, the exact underlying mechanisms remain unknown. Therefore, the current study investigated how valence and sociality of contextual information influenced the early and later stages of neutral face processing. We first employed an established affective learning procedure, wherein neutral faces were paired with verbal information that differed in valence (negative, neutral) and sociality (social, non-social), to manipulate contextual information. Then, to explore the effects of context on face perception, participants performed a face perception task, while the N170, early posterior negativity (EPN), and late positive potential (LPP) components were measured. Finally, to explore the effects of context on selective attention, participants performed a dot probe task while the N2pc was recorded. The results showed that, in the face perception task, faces paired with negative social information elicited greater EPN and LPP than did faces paired with neutral social information; no differences existed between faces paired with negative and neutral non-social information. In the dot probe task, faces paired with negative social information elicited a more negative N2pc amplitude (indicating attentional bias) than did faces paired with neutral social information; the N2pc did not differ between faces paired with negative and neutral non-social information. Together, these results suggest that contextual information influenced both face perception and selective attention, and these context

  15. Contextual Valence and Sociality Jointly Influence the Early and Later Stages of Neutral Face Processing

    PubMed Central

    Xu, Mengsi; Li, Zhiai; Diao, Liuting; Fan, Lingxia; Yang, Dong

    2016-01-01

    Recent studies have demonstrated that face perception is influenced by emotional contextual information. However, because facial expressions are routinely decoded and understood during social communication, sociality should also be considered—that is, it seems necessary to explore whether emotional contextual effects are influenced by the sociality of contextual information. Furthermore, although one behavioral study has explored the effects of context on selective attention to faces, the exact underlying mechanisms remain unknown. Therefore, the current study investigated how valence and sociality of contextual information influenced the early and later stages of neutral face processing. We first employed an established affective learning procedure, wherein neutral faces were paired with verbal information that differed in valence (negative, neutral) and sociality (social, non-social), to manipulate contextual information. Then, to explore the effects of context on face perception, participants performed a face perception task, while the N170, early posterior negativity (EPN), and late positive potential (LPP) components were measured. Finally, to explore the effects of context on selective attention, participants performed a dot probe task while the N2pc was recorded. The results showed that, in the face perception task, faces paired with negative social information elicited greater EPN and LPP than did faces paired with neutral social information; no differences existed between faces paired with negative and neutral non-social information. In the dot probe task, faces paired with negative social information elicited a more negative N2pc amplitude (indicating attentional bias) than did faces paired with neutral social information; the N2pc did not differ between faces paired with negative and neutral non-social information. Together, these results suggest that contextual information influenced both face perception and selective attention, and these context

  16. Contextual Valence and Sociality Jointly Influence the Early and Later Stages of Neutral Face Processing.

    PubMed

    Xu, Mengsi; Li, Zhiai; Diao, Liuting; Fan, Lingxia; Yang, Dong

    2016-01-01

    Recent studies have demonstrated that face perception is influenced by emotional contextual information. However, because facial expressions are routinely decoded and understood during social communication, sociality should also be considered-that is, it seems necessary to explore whether emotional contextual effects are influenced by the sociality of contextual information. Furthermore, although one behavioral study has explored the effects of context on selective attention to faces, the exact underlying mechanisms remain unknown. Therefore, the current study investigated how valence and sociality of contextual information influenced the early and later stages of neutral face processing. We first employed an established affective learning procedure, wherein neutral faces were paired with verbal information that differed in valence (negative, neutral) and sociality (social, non-social), to manipulate contextual information. Then, to explore the effects of context on face perception, participants performed a face perception task, while the N170, early posterior negativity (EPN), and late positive potential (LPP) components were measured. Finally, to explore the effects of context on selective attention, participants performed a dot probe task while the N2pc was recorded. The results showed that, in the face perception task, faces paired with negative social information elicited greater EPN and LPP than did faces paired with neutral social information; no differences existed between faces paired with negative and neutral non-social information. In the dot probe task, faces paired with negative social information elicited a more negative N2pc amplitude (indicating attentional bias) than did faces paired with neutral social information; the N2pc did not differ between faces paired with negative and neutral non-social information. Together, these results suggest that contextual information influenced both face perception and selective attention, and these context

  17. Dichotomy and perceptual distortions in absolute pitch ability.

    PubMed

    Athos, E Alexandra; Levinson, Barbara; Kistler, Amy; Zemansky, Jason; Bostrom, Alan; Freimer, Nelson; Gitschier, Jane

    2007-09-11

    Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a "perceptual magnet" centered at the note "A." In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the "sharp" direction. These findings speak both to the process of acquisition of AP and to its stability.

  18. Dichotomy and perceptual distortions in absolute pitch ability

    PubMed Central

    Athos, E. Alexandra; Levinson, Barbara; Kistler, Amy; Zemansky, Jason; Bostrom, Alan; Freimer, Nelson; Gitschier, Jane

    2007-01-01

    Absolute pitch (AP) is the rare ability to identify the pitch of a tone without the aid of a reference tone. Understanding both the nature and genesis of AP can provide insights into neuroplasticity in the auditory system. We explored factors that may influence the accuracy of pitch perception in AP subjects both during the development of the trait and in later age. We used a Web-based survey and a pitch-labeling test to collect perceptual data from 2,213 individuals, 981 (44%) of whom proved to have extraordinary pitch-naming ability. The bimodal distribution in pitch-naming ability signifies AP as a distinct perceptual trait, with possible implications for its genetic basis. The wealth of these data has allowed us to uncover unsuspected note-naming irregularities suggestive of a “perceptual magnet” centered at the note “A.” In addition, we document a gradual decline in pitch-naming accuracy with age, characterized by a perceptual shift in the “sharp” direction. These findings speak both to the process of acquisition of AP and to its stability. PMID:17724340

  19. Applying perceptual learning to achieve practical changes in vision

    PubMed Central

    Deveau, Jenni; Seitz, Aaron R.

    2014-01-01

    Research of visual perceptual learning has illuminated the flexibility of processing in the visual system and provides insights into therapeutic approaches to remediating some components of low vision. A key observation from research of perceptual learning is that effects of training are often highly specific to the attributes of the trained stimuli. This observation has been a blessing to basic research, providing important constraints to models of learning, but is a curse to translational research, which has the goal of creating therapies that generalize widely across visual tasks and stimuli. Here we suggest that the curse of specificity can be overcome by adopting a different experimental framework than is standard in the field. Namely, translational studies should integrate many approaches together and sacrifice mechanistic understanding to gain clinical relevance. To validate this argument, we review research from our lab and others, and also present new data, that together shows how perceptual learning on basic stimuli can lead to improvements on standard vision tests as well as real world vision use such as improved reading and even improved sports performance. Furthermore, we show evidence that this integrative approach to perceptual learning can ameliorate effects of presbyopia and provides promise to improve visual function for individuals suffering from low vision. PMID:25360128

  20. Applying perceptual learning to achieve practical changes in vision.

    PubMed

    Deveau, Jenni; Seitz, Aaron R

    2014-01-01

    Research of visual perceptual learning has illuminated the flexibility of processing in the visual system and provides insights into therapeutic approaches to remediating some components of low vision. A key observation from research of perceptual learning is that effects of training are often highly specific to the attributes of the trained stimuli. This observation has been a blessing to basic research, providing important constraints to models of learning, but is a curse to translational research, which has the goal of creating therapies that generalize widely across visual tasks and stimuli. Here we suggest that the curse of specificity can be overcome by adopting a different experimental framework than is standard in the field. Namely, translational studies should integrate many approaches together and sacrifice mechanistic understanding to gain clinical relevance. To validate this argument, we review research from our lab and others, and also present new data, that together shows how perceptual learning on basic stimuli can lead to improvements on standard vision tests as well as real world vision use such as improved reading and even improved sports performance. Furthermore, we show evidence that this integrative approach to perceptual learning can ameliorate effects of presbyopia and provides promise to improve visual function for individuals suffering from low vision.

  1. Predictive processing, perceptual presence, and sensorimotor theory.

    PubMed

    O'Regan, J Kevin; Degenaar, Jan

    2014-01-01

    Mastery of sensorimotor contingencies can be viewed as attunement to potentialities. In our view, these potentialities have wider application than recognized in Seth's account of sensory presence, and should pertain to all of sensory experience. Instead of appealing only to a notion of counterfactual richness, we propose that the degree of sensory presence can be further specified in terms of bodiliness, insubordinateness, and grabbiness. While PPSMC can provide a possible implementation of a sensorimotor account of synesthesia, we suggest it should be rid of its representationalist interpretation. PMID:24742075

  2. Perceptual load manipulation reveals sensitivity of the face-selective N170 to attention.

    PubMed

    Mohamed, Tarik N; Neumann, Markus F; Schweinberger, Stefan R

    2009-05-27

    It has been controversial whether the face-sensitive N170 is affected by selective attention. We manipulated attention sensu Lavie's perceptual load theory to short (200 ms) presentations of task-irrelevant unfamiliar faces or houses, while participants identified superimposed target letters 'X' versus 'N'. These targets were strings of either six identical (low load) or six different letters (high load). Under low load, we found a prominent face-selective N170 response. Under high load, however, we not only observed a dramatic reduction of the face N170 but also an unexpected enhancement of the house N170, such that face selectivity was almost completely lost. We conclude that the early stages of face processing indexed by the N170 strongly depend on selective attention. PMID:19369907

  3. Perceptual load manipulation reveals sensitivity of the face-selective N170 to attention.

    PubMed

    Mohamed, Tarik N; Neumann, Markus F; Schweinberger, Stefan R

    2009-05-27

    It has been controversial whether the face-sensitive N170 is affected by selective attention. We manipulated attention sensu Lavie's perceptual load theory to short (200 ms) presentations of task-irrelevant unfamiliar faces or houses, while participants identified superimposed target letters 'X' versus 'N'. These targets were strings of either six identical (low load) or six different letters (high load). Under low load, we found a prominent face-selective N170 response. Under high load, however, we not only observed a dramatic reduction of the face N170 but also an unexpected enhancement of the house N170, such that face selectivity was almost completely lost. We conclude that the early stages of face processing indexed by the N170 strongly depend on selective attention.

  4. Perceptual estimation obeys Occam's razor.

    PubMed

    Gershman, Samuel J; Niv, Yael

    2013-01-01

    Theoretical models of unsupervised category learning postulate that humans "invent" categories to accommodate new patterns, but tend to group stimuli into a small number of categories. This "Occam's razor" principle is motivated by normative rules of statistical inference. If categories influence perception, then one should find effects of category invention on simple perceptual estimation. In a series of experiments, we tested this prediction by asking participants to estimate the number of colored circles on a computer screen, with the number of circles drawn from a color-specific distribution. When the distributions associated with each color overlapped substantially, participants' estimates were biased toward values intermediate between the two means, indicating that subjects ignored the color of the circles and grouped different-colored stimuli into one perceptual category. These data suggest that humans favor simpler explanations of sensory inputs. In contrast, when the distributions associated with each color overlapped minimally, the bias was reduced (i.e., the estimates for each color were closer to the true means), indicating that sensory evidence for more complex explanations can override the simplicity bias. We present a rational analysis of our task, showing how these qualitative patterns can arise from Bayesian computations. PMID:24137136

  5. Perceptually lossy compression of documents

    NASA Astrophysics Data System (ADS)

    Beretta, Giordano B.; Bhaskaran, Vasudev; Konstantinides, Konstantinos; Natarajan, Balas R.

    1997-06-01

    The main cost of owning a facsimile machine consists of the telephone charges for the communications, thus short transmission times are a key feature for facsimile machines. Similarly, on a packet-routed service such as the Internet, a low number of packets is essential to avoid operator wait times. Concomitantly, the user expectations have increased considerably. In facsimile, the switch from binary to full color increases the data size by a factor of 24. On the Internet, the switch from plain text American Standard Code for Information Interchange (ASCII) encoded files to files marked up in the Hypertext Markup Language (HTML) with ample embedded graphics has increased the size of transactions by several orders of magnitude. A common compressing method for raster files in these applications in the Joint Photographic Experts Group (JPEG) method, because efficient implementations are readily available. In this method the implementors design the discrete quantization tables (DQT) and the Huffman tables (HT) to maximize the compression factor while maintaining the introduced artifacts at the threshold of perceptual detectability. Unfortunately the achieved compression rates are unsatisfactory for applications such as color facsimile and World Wide Web (W3) browsing. We present a design methodology for image-independent DQTs that while producing perceptually lossy data, does not impair the reading performance of users. Combined with a text sharpening algorithm that compensates for scanning device limitations, the methodology presented in this paper allows us to achieve compression ratios near 1:100.

  6. Building online brand perceptual map.

    PubMed

    Chiang, I-Ping; Lin, Chih-Ying; Wang, Kaisheng M

    2008-10-01

    Many companies have launched their products or services online as a new business focus, but only a few of them have survived the competition and made profits. The most important key to an online business's success is to create "brand value" for the customers. Although the concept of online brand has been discussed in previous studies, there is no empirical study on the measurement of online branding. As Web 2.0 emerges to be critical to online branding, the purpose of this study was to measure Taiwan's major Web sites with a number of personality traits to build a perceptual map for online brands. A pretest identified 10 most representative online brand perceptions. The results of the correspondence analysis showed five groups in the perceptual map. This study provided a practical view of the associations and similarities among online brands for potential alliance or branding strategies. The findings also suggested that brand perceptions can be used with identified consumer needs and behaviors to better position online services. The brand perception map in the study also contributed to a better understanding of the online brands in Taiwan.

  7. Building online brand perceptual map.

    PubMed

    Chiang, I-Ping; Lin, Chih-Ying; Wang, Kaisheng M

    2008-10-01

    Many companies have launched their products or services online as a new business focus, but only a few of them have survived the competition and made profits. The most important key to an online business's success is to create "brand value" for the customers. Although the concept of online brand has been discussed in previous studies, there is no empirical study on the measurement of online branding. As Web 2.0 emerges to be critical to online branding, the purpose of this study was to measure Taiwan's major Web sites with a number of personality traits to build a perceptual map for online brands. A pretest identified 10 most representative online brand perceptions. The results of the correspondence analysis showed five groups in the perceptual map. This study provided a practical view of the associations and similarities among online brands for potential alliance or branding strategies. The findings also suggested that brand perceptions can be used with identified consumer needs and behaviors to better position online services. The brand perception map in the study also contributed to a better understanding of the online brands in Taiwan. PMID:18785819

  8. Mathematical modeling of a continuous alcoholic fermentation process in a two-stage tower reactor cascade with flocculating yeast recycle.

    PubMed

    de Oliveira, Samuel Conceição; de Castro, Heizir Ferreira; Visconti, Alexandre Eliseu Stourdze; Giudici, Reinaldo

    2015-03-01

    Experiments of continuous alcoholic fermentation of sugarcane juice with flocculating yeast recycle were conducted in a system of two 0.22-L tower bioreactors in series, operated at a range of dilution rates (D 1 = D 2 = 0.27-0.95 h(-1)), constant recycle ratio (α = F R /F = 4.0) and a sugar concentration in the feed stream (S 0) around 150 g/L. The data obtained in these experimental conditions were used to adjust the parameters of a mathematical model previously developed for the single-stage process. This model considers each of the tower bioreactors as a perfectly mixed continuous reactor and the kinetics of cell growth and product formation takes into account the limitation by substrate and the inhibition by ethanol and biomass, as well as the substrate consumption for cellular maintenance. The model predictions agreed satisfactorily with the measurements taken in both stages of the cascade. The major differences with respect to the kinetic parameters previously estimated for a single-stage system were observed for the maximum specific growth rate, for the inhibition constants of cell growth and for the specific rate of substrate consumption for cell maintenance. Mathematical models were validated and used to simulate alternative operating conditions as well as to analyze the performance of the two-stage process against that of the single-stage process.

  9. Applying Transcranial Magnetic Stimulation (TMS) Over the Dorsal Visual Pathway Induces Schizophrenia-like Disruption of Perceptual Closure.

    PubMed

    Amiaz, Revital; Vainiger, Dana; Gershon, Ari A; Weiser, Mark; Lavidor, Michal; Javitt, Daniel C

    2016-07-01

    Perceptual closure ability is postulated to depend upon rapid transmission of magnocellular information to prefrontal cortex via the dorsal stream. In contrast, illusory contour processing requires only local interactions within primary and ventral stream visual regions, such as lateral occipital complex. Schizophrenia is associated with deficits in perceptual closure versus illusory contours processing that is hypothesized to reflect impaired magnocellular/dorsal stream. Perceptual closure and illusory contours performance was evaluated in separate groups of 12 healthy volunteers during no TMS, and during repetitive 10 Hz rTMS stimulation over dorsal stream or vertex (TMS-vertex). Perceptual closure and illusory contours were performed in 11 schizophrenia patients, no TMS was applied in these patients. TMS effects were evaluated with repeated measures ANOVA across treatments. rTMS significantly increased perceptual closure identification thresholds, with significant difference between TMS-dorsal stream and no TMS. TMS-dorsal stream also significantly reduced perceptual closure but not illusory contours accuracy. Schizophrenia patients showed increased perceptual closure identification thresholds relative to controls in the no TMS condition, but similar to controls in the TMS-dorsal stream condition. Conclusions of this study are that magnocellular/dorsal stream input is critical for perceptual closure but not illusory contours performance, supporting both trickledown theories of normal perceptual closure function, and magnocellular/dorsal stream theories of visual dysfunction in schizophrenia.

  10. Perceptual Factors and Learning in Digital Environments

    ERIC Educational Resources Information Center

    Paek, Seungoh; Hoffman, Daniel L.; Black, John B.

    2016-01-01

    The purpose of this study was to examine if student understanding of new material could be promoted by manipulating the perceptual factors experienced at the time of learning. It was hypothesized that the thematic relevance of perceptual factors would be a significant contributor to learner understanding. To test this hypothesis, one hundred…

  11. Perceptual Differences between Hippies and College Students

    ERIC Educational Resources Information Center

    Brothers, Robert; Gaines, Rosslyn

    1973-01-01

    Perceptual differences were investigated between 50 college students who were non-drug users and 50 hippies who used LSD. The major hypothesis predicted was that hippies would score differently from college students in a specific direction on each of the perceptual tasks. (Author)

  12. Perceptual effects of linguistic category priming: the Stapel and Semin (2007) paradigm revisited in twelve experiments.

    PubMed

    IJzerman, Hans; Regenberg, Nina F E; Saddlemyer, Justin; Koole, Sander L

    2015-05-01

    Linguistic category priming is a novel paradigm to examine automatic influences of language on cognition (Semin, 2008). An initial article reported that priming abstract linguistic categories (adjectives) led to more global perceptual processing, whereas priming concrete linguistic categories (verbs) led to more local perceptual processing (Stapel & Semin, 2007). However, this report was compromised by data fabrication by the first author, so that it remains unclear whether or not linguistic category priming influences perceptual processing. To fill this gap in the literature, the present article reports 12 studies among Dutch and US samples examining the perceptual effects of linguistic category priming. The results yielded no evidence of linguistic category priming effects. These findings are discussed in relation to other research showing cultural variations in linguistic category priming effects (IJzerman, Saddlemyer, & Koole, 2014). The authors conclude by highlighting the importance of conducting and publishing replication research for achieving scientific progress.

  13. Is Children's Acquisition of the Passive a Staged Process? Evidence from Six- and Nine-Year-Olds' Production of Passives

    ERIC Educational Resources Information Center

    Messenger, Katherine; Branigan, Holly P.; McLean, Janet F.

    2012-01-01

    We report a syntactic priming experiment that examined whether children's acquisition of the passive is a staged process, with acquisition of constituent structure preceding acquisition of thematic role mappings. Six-year-olds and nine-year-olds described transitive actions after hearing active and passive prime descriptions involving the same or…

  14. Lexical Access in Early Stages of Visual Word Processing: A Single-Trial Correlational MEG Study of Heteronym Recognition

    ERIC Educational Resources Information Center

    Solomyak, Olla; Marantz, Alec

    2009-01-01

    We present an MEG study of heteronym recognition, aiming to distinguish between two theories of lexical access: the "early access" theory, which entails that lexical access occurs at early (pre 200 ms) stages of processing, and the "late access" theory, which interprets this early activity as orthographic word-form identification rather than…

  15. 29 CFR 102.97 - Expeditious processing of section 10(l) and (m) cases in successive stages.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 2 2010-07-01 2010-07-01 false Expeditious processing of section 10(l) and (m) cases in successive stages. 102.97 Section 102.97 Labor Regulations Relating to Labor NATIONAL LABOR RELATIONS BOARD RULES AND REGULATIONS, SERIES 8 Procedure in Cases Under Section 10(j), (l), and (m) of the Act §...

  16. Develop apparatus and process for second-stage drying. Quarterly progress report, September 26--December 26, 1994

    SciTech Connect

    Taylor, F.

    1995-01-05

    Progress is reported on Task 1, Computer simulation refinement and extension, and its two subtasks: Verification of computer model simulation of the drying process for lumber in a superheated kiln and Establishment of energy loss predictions for specific kiln designs for the first stage kiln. A report of a trip to the Irvington Moore Corporation facility and plans for next quarter are described.

  17. 29 CFR 102.97 - Expeditious processing of section 10(l) and (m) cases in successive stages.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 2 2011-07-01 2011-07-01 false Expeditious processing of section 10(l) and (m) cases in successive stages. 102.97 Section 102.97 Labor Regulations Relating to Labor NATIONAL LABOR RELATIONS BOARD RULES AND REGULATIONS, SERIES 8 Procedure in Cases Under Section 10(j), (l), and (m) of the Act §...

  18. Computer Simulations in the High School: Students' Cognitive Stages, Science Process Skills and Academic Achievement in Microbiology.

    ERIC Educational Resources Information Center

    Huppert, J.; Lomask, S. Michal; Lazarowitz, R.

    2002-01-01

    Investigates the impact of computer simulation on students' academic achievement and their mastery of science process skills with regard to their cognitive stages. Based on the computer simulation program "The Growth Curve of Microorganisms" which requires 10th grade biology students to use problem solving skills while simultaneously manipulating…

  19. Characterization of fibrillation process of {alpha}-synuclein at the initial stage

    SciTech Connect

    Tashiro, Mitsuru; Kojima, Masaki; Kihara, Hiroshi; Kasai, Kouki; Kamiyoshihara, Tomoaki; Ueda, Kenji; Shimotakahara, Sakurako

    2008-05-09

    {alpha}-Synuclein is the major component of the filamentous Lewy bodies and Lewy-related neurites, neuropathological hallmarks of Parkinson's disease. Although numerous studies on {alpha}-synuclein fibrillation have been reported, the molecular mechanisms of aggregation and fibrillation at the initial stage are still unclear. In the present study, structural properties and propensities to form fibrils of {alpha}-synuclein at the initial stage were investigated using 2D {sup 1}H-{sup 15}N NMR spectroscopy, electron microscope, and small angle X-ray scattering (SAXS). Observation of the 2D {sup 1}H-{sup 15}N HSQC spectra indicated significant attenuation of many cross peak intensities in the regions of KTKEGV-type repeats and the non-A{beta} component of Alzheimer's disease amyloid (NAC), suggesting that these regions contributed fibril formation. Oligomerization comprising heptamer was successfully monitored at the initial stage using the time-dependent SAXS measurements.

  20. [The pathomorphology of complicated colorectal cancer and the stages in the development of the tumor process].

    PubMed

    Iarŭmov, N; Popkhristova, E; Viiachki, I; Terziev, I; Gachev, N

    1999-01-01

    A comprehensive pathomorphological assessment is done in 385 patients presenting complicated colorectal carcinoma, covering the period 1990 through 1995. The patients are distributed in 4 groups according to stage, with those in stage III being the most numerous--141 cases. The growth pattern of the neoplasm is as follows: exophytic growth--110 cases, ulcerous growth--57, cup-like growth--13, and endophytic growth--205 cases. On establishing metastatic lymph nodes within I and II lymph collectors, prophylactic postoperative chemo- and immunotherapy are undertaken. In case of lymph nodes present in III lymph collector, the operation is taken to be relatively radical, and for that reason chemo- and immunotherapy assume a therapeutic character.