Implicit interpretation biases affect emotional vulnerability: a training study.

PubMed

Tran, Tanya B; Siemer, Matthias; Joormann, Jutta

2011-04-01

Cognitive theories of emotion propose that the interpretation of emotion-eliciting situations crucially shapes affective responses. Implicit or automatic biases in these interpretations may hinder emotion regulation and thereby increase risk for the onset and maintenance of psychological disorders. In this study, participants were randomly assigned to a positive or negative interpretation bias training using ambiguous social scenarios. After the completion of the training, a stress task was administered and changes in positive and negative affect and self-esteem were assessed. The results demonstrate that the interpretation bias training was successful in that participants exhibited a tendency to interpret novel scenarios in accordance with their training condition. Importantly, the positive training condition also had a protective effect on self-esteem. Participants in this condition did not exhibit a decrease in self-esteem after the stress task, whereas participants in the negative condition did. These results demonstrate that implicit cognitive biases can be trained and that this training affects self-esteem. Implications of these findings for research on psychopathology and emotion regulation are discussed. © 2011 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

Positive affect promotes well-being and alleviates depression: The mediating effect of attentional bias.

PubMed

Xu, Yuanyuan; Yu, Yongju; Xie, Yuanjun; Peng, Li; Liu, Botao; Xie, Junrun; Bian, Chen; Li, Min

2015-08-30

The present study tested whether the relationships among positive affect, psychological well-being, life satisfaction and depression could be explained by positive and negative attentional bias. Structural equation modeling and mediation analyses were conducted based on 565 medical freshmen in China. The model of attentional bias as a mediator between positive affect promoting well-being and decreasing depression fit the data. Finding showed positive affect significantly related to positive and negative attentional biases. People who had higher level of positive affect held more positive attentional bias and less negative attentional bias, and reported higher levels of psychological well-being, life satisfaction and lower levels of depression. The utility of the attentional bias as the mechanism through which positive affect enhances well-being and alleviates depression was supported. Applications in cultivating positive affect and regulating attentional bias in counseling and education are discussed. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Lower Risk of Death With SGLT2 Inhibitors in Observational Studies: Real or Bias?

PubMed

Suissa, Samy

2018-01-01

Two recent observational studies reported a remarkably lower rate of all-cause death associated with sodium-glucose cotransporter 2 inhibitor (-SGLT2i) use in all patients with type 2 diabetes and not only those at increased cardiovascular risk. The >50% lower mortality rates reported in these studies are much greater than those found in the BI 10773 (Empagliflozin) Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients (EMPA-REG OUTCOME) and CANagliflozin cardioVascular Assessment Study (CANVAS) randomized trials. We show that these observational studies are affected by time-related biases, including immortal time bias and time-lag bias, which tend to exaggerate the benefits observed with a drug. The Comparative Effectiveness of Cardiovascular Outcomes in New Users of SGLT-2 Inhibitors (CVD-REAL) study, based on 166,033 users of SGLT2i and 1,226,221 users of other glucose-lowering drugs (oGLD) identified from health care databases of six countries, was affected by immortal time bias. Indeed, the immortal time between the first oGLD prescription and the first SGLT2i prescription was omitted from the analysis, which resulted in increasing the rate of death in the oGLD group and thus producing the appearance of a lower risk of death with SGLT2i use. The Swedish study compared 10,879 SGLT2i/dipeptidyl peptidase 4 inhibitor (DPP-4i) users with 10,879 matched insulin users. Such comparisons involving second-line therapies with a third-line therapy can introduce time-lag bias, as the patients may not be at the same stage of diabetes. This bias is compounded by the fact that the users of insulin had already started their insulin before cohort entry, unlike the new users of SGLT2i. Finally, the study also introduces immortal time bias with respect to the effects of SGLT2i relative to DPP-4i. In conclusion, the >50% lower rate of death with SGLT2i in type 2 diabetes reported by two recent observational studies is likely exaggerated by immortal time and time

How does bias correction of regional climate model precipitation affect modelled runoff?

NASA Astrophysics Data System (ADS)

Teng, J.; Potter, N. J.; Chiew, F. H. S.; Zhang, L.; Wang, B.; Vaze, J.; Evans, J. P.

2015-02-01

Many studies bias correct daily precipitation from climate models to match the observed precipitation statistics, and the bias corrected data are then used for various modelling applications. This paper presents a review of recent methods used to bias correct precipitation from regional climate models (RCMs). The paper then assesses four bias correction methods applied to the weather research and forecasting (WRF) model simulated precipitation, and the follow-on impact on modelled runoff for eight catchments in southeast Australia. Overall, the best results are produced by either quantile mapping or a newly proposed two-state gamma distribution mapping method. However, the differences between the methods are small in the modelling experiments here (and as reported in the literature), mainly due to the substantial corrections required and inconsistent errors over time (non-stationarity). The errors in bias corrected precipitation are typically amplified in modelled runoff. The tested methods cannot overcome limitations of the RCM in simulating precipitation sequence, which affects runoff generation. Results further show that whereas bias correction does not seem to alter change signals in precipitation means, it can introduce additional uncertainty to change signals in high precipitation amounts and, consequently, in runoff. Future climate change impact studies need to take this into account when deciding whether to use raw or bias corrected RCM results. Nevertheless, RCMs will continue to improve and will become increasingly useful for hydrological applications as the bias in RCM simulations reduces.

Observer Biases in the Classroom.

ERIC Educational Resources Information Center

Kite, Mary E.

1991-01-01

Presents three student exercises that demonstrate common perceptual errors described in social psychological literature: actor-observer effect, false consensus bias, and priming effects. Describes methods to be followed and gives terms, sentences, and a story to be used in the exercises. Suggests discussion of the bases and impact of such…

Data assimilation in integrated hydrological modelling in the presence of observation bias

NASA Astrophysics Data System (ADS)

Rasmussen, J.; Madsen, H.; Jensen, K. H.; Refsgaard, J. C.

2015-08-01

The use of bias-aware Kalman filters for estimating and correcting observation bias in groundwater head observations is evaluated using both synthetic and real observations. In the synthetic test, groundwater head observations with a constant bias and unbiased stream discharge observations are assimilated in a catchment scale integrated hydrological model with the aim of updating stream discharge and groundwater head, as well as several model parameters relating to both stream flow and groundwater modeling. The Colored Noise Kalman filter (ColKF) and the Separate bias Kalman filter (SepKF) are tested and evaluated for correcting the observation biases. The study found that both methods were able to estimate most of the biases and that using any of the two bias estimation methods resulted in significant improvements over using a bias-unaware Kalman Filter. While the convergence of the ColKF was significantly faster than the convergence of the SepKF, a much larger ensemble size was required as the estimation of biases would otherwise fail. Real observations of groundwater head and stream discharge were also assimilated, resulting in improved stream flow modeling in terms of an increased Nash-Sutcliffe coefficient while no clear improvement in groundwater head modeling was observed. Both the ColKF and the SepKF tended to underestimate the biases, which resulted in drifting model behavior and sub-optimal parameter estimation, but both methods provided better state updating and parameter estimation than using a bias-unaware filter.

Data assimilation in integrated hydrological modelling in the presence of observation bias

NASA Astrophysics Data System (ADS)

Rasmussen, Jørn; Madsen, Henrik; Høgh Jensen, Karsten; Refsgaard, Jens Christian

2016-05-01

The use of bias-aware Kalman filters for estimating and correcting observation bias in groundwater head observations is evaluated using both synthetic and real observations. In the synthetic test, groundwater head observations with a constant bias and unbiased stream discharge observations are assimilated in a catchment-scale integrated hydrological model with the aim of updating stream discharge and groundwater head, as well as several model parameters relating to both streamflow and groundwater modelling. The coloured noise Kalman filter (ColKF) and the separate-bias Kalman filter (SepKF) are tested and evaluated for correcting the observation biases. The study found that both methods were able to estimate most of the biases and that using any of the two bias estimation methods resulted in significant improvements over using a bias-unaware Kalman filter. While the convergence of the ColKF was significantly faster than the convergence of the SepKF, a much larger ensemble size was required as the estimation of biases would otherwise fail. Real observations of groundwater head and stream discharge were also assimilated, resulting in improved streamflow modelling in terms of an increased Nash-Sutcliffe coefficient while no clear improvement in groundwater head modelling was observed. Both the ColKF and the SepKF tended to underestimate the biases, which resulted in drifting model behaviour and sub-optimal parameter estimation, but both methods provided better state updating and parameter estimation than using a bias-unaware filter.

Affective biasing of choices in gambling task decision making.

PubMed

Hinson, John M; Whitney, Paul; Holben, Heather; Wirick, Aaron K

2006-09-01

The proponents of the somatic marker hypothesis presume that rational decision making is guided by emotional reactions that are developed from prior experience. Supporting evidence for the hypothesis comes almost exclusively from the short-term affective reactions that are learned during the course of a hypothetical decision-making task--the gambling task (GT). We examined GT performance and affective reactions to choices when those choices were biased by words that had preexisting affective value. In one experiment, affectively valued words directly signaled good and bad choices. A congruent relation between affective value of word and choice outcome improved GT performance, whereas an incongruent relation greatly interfered with performance. In another experiment, affectively valued words were maintained as a working memory (WM) load between GT choices. A WM load with affectively positive words somewhat improved GT performance, whereas affectively negative words interfered with performance. Somatic markers-indicated by differential anticipatory skin conductance response (SCR) amplitude for good and bad choices-appeared at a point in the GT session when choice performance was superior. However, differential SCR developed during the session after good choice performance was already established. These results indicate that preexisting affective biases can influence GT decision making. In addition, the somatic markers that are regular accompaniments of GT decision making appeared to be temporally lagging indicators of choice performance.

Hindsight bias: how knowledge and heuristics affect our reconstruction of the past.

PubMed

Hertwig, Ralph; Fanselow, Carola; Hoffrage, Ulrich

2003-01-01

Once people know the outcome of an event, they tend to overestimate what could have been anticipated in foresight. Although typically considered to be a robust phenomenon, this hindsight bias is subject to moderating circumstances. In their meta-analysis, Christensen-Szalanski and Willham (1991) observed that the more experience people have with the task under consideration, the smaller is the resulting hindsight bias. This observation is one benchmark against which the explanatory power of process models of hindsight bias can be measured. Therefore, we used it to put the recently proposed RAFT model (Hoffrage, Hertwig, & Gigerenzer, 2000) to another test. Our findings were consistent with the "expertise effect." Specifically, we observed-using computer simulations of the RAFT model-that the more comprehensive people's knowledge is in foresight, the smaller is their hindsight bias. In addition, we made two counterintuitive observations: First, the relation between foresight knowledge and hindsight bias appears to be independent of how knowledge is processed. Second, even if foresight knowledge is false, it can reduce hindsight bias. We conclude with a discussion of the functional value of hindsight bias.

Applying signal-detection theory to the study of observer accuracy and bias in behavioral assessment.

PubMed

Lerman, Dorothea C; Tetreault, Allison; Hovanetz, Alyson; Bellaci, Emily; Miller, Jonathan; Karp, Hilary; Mahmood, Angela; Strobel, Maggie; Mullen, Shelley; Keyl, Alice; Toupard, Alexis

2010-01-01

We evaluated the feasibility and utility of a laboratory model for examining observer accuracy within the framework of signal-detection theory (SDT). Sixty-one individuals collected data on aggression while viewing videotaped segments of simulated teacher-child interactions. The purpose of Experiment 1 was to determine if brief feedback and contingencies for scoring accurately would bias responding reliably. Experiment 2 focused on one variable (specificity of the operational definition) that we hypothesized might decrease the likelihood of bias. The effects of social consequences and information about expected behavior change were examined in Experiment 3. Results indicated that feedback and contingencies reliably biased responding and that the clarity of the definition only moderately affected this outcome.

Biased learning affects mate choice in a butterfly.

PubMed

Westerman, Erica L; Hodgins-Davis, Andrea; Dinwiddie, April; Monteiro, Antónia

2012-07-03

Early acquisition of mate preferences or mate-preference learning is associated with signal diversity and speciation in a wide variety of animal species. However, the diversity of mechanisms of mate-preference learning across taxa remains poorly understood. Using the butterfly Bicyclus anynana we uncover a mechanism that can lead to directional sexual selection via mate-preference learning: a bias in learning enhanced ornamentation, which is independent of preexisting mating biases. Naïve females mated preferentially with wild-type males over males with enhanced wing ornamentation, but females briefly exposed to enhanced males mated significantly more often with enhanced males. In contrast, females exposed to males with reduced wing ornamentation did not learn to prefer drab males. Thus, we observe both a learned change of a preexisting mating bias, and a bias in ability to learn enhanced male ornaments over reduced ornaments. Our findings demonstrate that females are able to change their preferences in response to a single social event, and suggest a role for biased learning in the evolution of visual sexual ornamentation.

Modelling cognitive affective biases in major depressive disorder using rodents

PubMed Central

Hales, Claire A; Stuart, Sarah A; Anderson, Michael H; Robinson, Emma S J

2014-01-01

Major depressive disorder (MDD) affects more than 10% of the population, although our understanding of the underlying aetiology of the disease and how antidepressant drugs act to remediate symptoms is limited. Major obstacles include the lack of availability of good animal models that replicate aspects of the phenotype and tests to assay depression-like behaviour in non-human species. To date, research in rodents has been dominated by two types of assays designed to test for depression-like behaviour: behavioural despair tests, such as the forced swim test, and measures of anhedonia, such as the sucrose preference test. These tests have shown relatively good predictive validity in terms of antidepressant efficacy, but have limited translational validity. Recent developments in clinical research have revealed that cognitive affective biases (CABs) are a key feature of MDD. Through the development of neuropsychological tests to provide objective measures of CAB in humans, we have the opportunity to use ‘reverse translation’ to develop and evaluate whether similar methods are suitable for research into MDD using animals. The first example of this approach was reported in 2004 where rodents in a putative negative affective state were shown to exhibit pessimistic choices in a judgement bias task. Subsequent work in both judgement bias tests and a novel affective bias task suggest that these types of assay may provide translational methods for studying MDD using animals. This review considers recent work in this area and the pharmacological and translational validity of these new animal models of CABs. Linked Articles This article is part of a themed section on Animal Models in Psychiatry Research. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-20 PMID:24467454

The nature of assembly bias - III. Observational properties

NASA Astrophysics Data System (ADS)

Lacerna, Ivan; Padilla, Nelson; Stasyszyn, Federico

2014-10-01

We analyse galaxies in groups in the Sloan Digital Sky Survey (SDSS) and find a weak but significant assembly-type bias, where old central galaxies have a higher clustering amplitude (61 ± 9 per cent) at scales >1 h-1 Mpc than young central galaxies of equal host halo mass (Mh ˜ 1011.8 h- 1 M⊙). The observational sample is volume limited out to z = 0.1 with Mr - 5 log (h) ≤ -19.6. We construct a mock catalogue of galaxies that shows a similar signal of assembly bias (46 ± 9 per cent) at the same halo mass. We then adapt the model presented by Lacerna & Padilla (Paper I) to redefine the overdensity peak height, which traces the assembly bias such that galaxies in equal density peaks show the same clustering regardless of their stellar age, but this time using observational features such as a flux limit. The proxy for peak height, which is proposed as a better alternative than the virial mass, consists in the total mass given by the mass of neighbour host haloes in cylinders centred at each central galaxy. The radius of the cylinder is parameterized as a function of stellar age and virial mass. The best-fitting sets of parameters that make the assembly bias signal lower than 5-15 per cent for both SDSS and mock central galaxies are similar. The idea behind the parameterization is not to minimize the bias, but it is to use this method to understand the physical features that produce the assembly bias effect. Even though the tracers of the density field used here differ significantly from those used in Paper I, our analysis of the simulated catalogue indicates that the different tracers produce correlated proxies, and therefore the reason behind assembly bias is the crowding of peaks in both simulations and the SDSS.

Attentional and affective biases for attractive females emerge early in development.

PubMed

Rennels, Jennifer Lynn; Verba, Stephanie Ann

2017-01-01

Predominant experience with females early in development results in infants developing an attractive, female-like facial representation that guides children's attention toward and affective preferences for attractive females. When combined with increased interest in the other sex at puberty, these early emerging biases might help explain the robust prosocial and financial biases men exhibit toward attractive women during adulthood.

Framing obesity a disease: Indirect effects of affect and controllability beliefs on weight bias.

PubMed

Nutter, Sarah; Alberga, Angela S; MacInnis, Cara; Ellard, John H; Russell-Mayhew, Shelly

2018-05-24

Obesity has been declared a disease by the American and Canadian Medical Associations. Although these declarations sparked much debate as to the impact of framing obesity as a disease on weight bias, strong empirical research is needed to examine this impact. The current study examined the impact of framing obesity a disease on weight bias, focusing on moderating and mediating processes. A sample of 309 participants living in the United States or Canada was recruited from Crowdflower. Participants completed measures of demographics, ideology, general attitudes, and previous contact quality and quantity with people living with obesity. Participants then read one of three articles as part of an experimental manipulation framing obesity as a disease, obesity not as a disease, and a control article unrelated to obesity. Post-manipulation included measures of affect, disgust, empathy, blame, and weight bias. Orthogonal contrasts were used to compare the obesity-disease condition to the obesity-not-disease condition and control condition. The manipulation had a direct effect on affect (emotions), such that affect toward individuals with obesity was more positive in the obesity-disease condition than the obesity-not-disease and control condition combined. Exploration of moderating effects revealed that both the belief in a just world and weight satisfaction moderated the relationship between the obesity-disease manipulation and blame for obesity. Two models of indirect effects on weight bias were also examined, which demonstrated that the obesity-disease manipulation predicted less weight bias through more positive affect (model 1) as well as less weight bias through decreased blame among individuals high in belief in a just world (model 2). This study further highlights the complex effects of declaring obesity a disease, uncovering a new direction for future research into the role of affect as well as indirect effects of characterising obesity a disease on weight bias.

Estimation and correction of different flavors of surface observation biases in ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Lorente-Plazas, Raquel; Hacker, Josua P.; Collins, Nancy; Lee, Jared A.

2017-04-01

The impact of assimilating surface observations has been shown in several publications, for improving weather prediction inside of the boundary layer as well as the flow aloft. However, the assimilation of surface observations is often far from optimal due to the presence of both model and observation biases. The sources of these biases can be diverse: an instrumental offset, errors associated to the comparison of point-based observations and grid-cell average, etc. To overcome this challenge, a method was developed using the ensemble Kalman filter. The approach consists on representing each observation bias as a parameter. These bias parameters are added to the forward operator and they extend the state vector. As opposed to the observation bias estimation approaches most common in operational systems (e.g. for satellite radiances), the state vector and parameters are simultaneously updated by applying the Kalman filter equations to the augmented state. The method to estimate and correct the observation bias is evaluated using observing system simulation experiments (OSSEs) with the Weather Research and Forecasting (WRF) model. OSSEs are constructed for the conventional observation network including radiosondes, aircraft observations, atmospheric motion vectors, and surface observations. Three different kinds of biases are added to 2-meter temperature for synthetic METARs. From the simplest to more sophisticated, imposed biases are: (1) a spatially invariant bias, (2) a spatially varying bias proportional to topographic height differences between the model and the observations, and (3) bias that is proportional to the temperature. The target region characterized by complex terrain is the western U.S. on a domain with 30-km grid spacing. Observations are assimilated every 3 hours using an 80-member ensemble during September 2012. Results demonstrate that the approach is able to estimate and correct the bias when it is spatially invariant (experiment 1). More

A bias-adjusted evidence synthesis of RCT and observational data: the case of total hip replacement.

PubMed

Schnell-Inderst, Petra; Iglesias, Cynthia P; Arvandi, Marjan; Ciani, Oriana; Matteucci Gothe, Raffaella; Peters, Jaime; Blom, Ashley W; Taylor, Rod S; Siebert, Uwe

2017-02-01

Evaluation of clinical effectiveness of medical devices differs in some aspects from the evaluation of pharmaceuticals. One of the main challenges identified is lack of robust evidence and a will to make use of experimental and observational studies (OSs) in quantitative evidence synthesis accounting for internal and external biases. Using a case study of total hip replacement to compare the risk of revision of cemented and uncemented implant fixation modalities, we pooled treatment effect estimates from OS and RCTs, and simplified existing methods for bias-adjusted evidence synthesis to enhance practical application. We performed an elicitation exercise using methodological and clinical experts to determine the strength of beliefs about the magnitude of internal and external bias affecting estimates of treatment effect. We incorporated the bias-adjusted treatment effects into a generalized evidence synthesis, calculating both frequentist and Bayesian statistical models. We estimated relative risks as summary effect estimates with 95% confidence/credibility intervals to capture uncertainty. When we compared alternative approaches to synthesizing evidence, we found that the pooled effect size strongly depended on the inclusion of observational data as well as on the use bias-adjusted estimates. We demonstrated the feasibility of using observational studies in meta-analyses to complement RCTs and incorporate evidence from a wider spectrum of clinically relevant studies and healthcare settings. To ensure internal validity, OS data require sufficient correction for confounding and selection bias, either through study design and primary analysis, or by applying post-hoc bias adjustments to the results. © 2017 The Authors. Health Economics published by John Wiley & Sons, Ltd. © 2017 The Authors. Health Economics published by John Wiley & Sons, Ltd.

The impact bias in self and others: Affective and empathic forecasting in individuals with social anxiety.

PubMed

Arditte Hall, Kimberly A; Joormann, Jutta; Siemer, Matthias; Timpano, Kiara R

2018-07-01

People tend to overestimate the intensity and duration of affect (i.e., impact bias) when making predictions about their own and others' responding, termed affective and empathic forecasting, respectively. Research links impact biases to clinical symptoms of affective disorders, but little work has been done to examine how social anxiety is related to affective and empathic forecasting biases. The current investigation included two studies examining these associations in independent samples of young adults with dimensionally distributed social anxiety symptoms. Study 1 (N = 100) examined the associations between social anxiety and affective and empathic forecasts in response to a series of novel hypothetical vignettes in which a second-person narrator (i.e., the self) elicited anger, disgust, or happiness from another person (i.e., the other). Study 2 utilized an innovative experimental paradigm involving N = 68 participant dyads. Overall, results supported the existence of affective and empathic forecasting biases. Further, symptoms of social anxiety were associated with the tendency to overestimate one's own and others' negative affect and underestimate others' positive affect. Such forecasting biases may help to explain the avoidance that is characteristic of individuals with social anxiety and could represent a fruitful target of cognitive behavioral intervention. Copyright © 2018 Elsevier Ltd. All rights reserved.

Affective modulation of external misattribution bias in source monitoring in schizophrenia.

PubMed

Costafreda, S G; Brébion, G; Allen, P; McGuire, P K; Fu, C H Y

2008-06-01

Schizophrenic patients tend to attribute internal events to external agents, a bias that may be linked to positive symptoms. We investigated the effect of emotional valence on the cognitive bias. Male schizophrenic subjects (n=30) and an experimenter alternatively produced neutral and negative words. The subject then decided whether he or the experimenter had generated the item. External misattributions were more common than self-misattributions, and the bias was greater for patients with active hallucinations and delusions relative to patients in remission. Actively psychotic patients but not patients in remission were more likely to generate external misattributions with negative relative to neutral words. Affective modulation of the externalizing cognitive bias in source monitoring is evident in patients with hallucinations and delusions.

An Eye Tracking Investigation of Attentional Biases towards Affect in Young Children

ERIC Educational Resources Information Center

Burris, Jessica L.; Barry-Anwar, Ryan A.; Rivera, Susan M.

2017-01-01

This study examines attentional biases in the presence of angry, happy and neutral faces using a modified eye tracking version of the dot probe task (DPT). Participants were 111 young children between 9 and 48 months. Children passively viewed an affective attention bias task that consisted of a face pairing (neutral paired with either neutral,…

Smokers exhibit biased neural processing of smoking and affective images.

PubMed

Oliver, Jason A; Jentink, Kade G; Drobes, David J; Evans, David E

2016-08-01

There has been growing interest in the role that implicit processing of drug cues can play in motivating drug use behavior. However, the extent to which drug cue processing biases relate to the processing biases exhibited to other types of evocative stimuli is largely unknown. The goal of the present study was to determine how the implicit cognitive processing of smoking cues relates to the processing of affective cues using a novel paradigm. Smokers (n = 50) and nonsmokers (n = 38) completed a picture-viewing task, in which participants were presented with a series of smoking, pleasant, unpleasant, and neutral images while engaging in a distractor task designed to direct controlled resources away from conscious processing of image content. Electroencephalogram recordings were obtained throughout the task for extraction of event-related potentials (ERPs). Smokers exhibited differential processing of smoking cues across 3 different ERP indices compared with nonsmokers. Comparable effects were found for pleasant cues on 2 of these indices. Late cognitive processing of smoking and pleasant cues was associated with nicotine dependence and cigarette use. Results suggest that cognitive biases may extend across classes of stimuli among smokers. This raises important questions about the fundamental meaning of cognitive biases, and suggests the need to consider generalized cognitive biases in theories of drug use behavior and interventions based on cognitive bias modification. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Biases in affective forecasting and recall in individuals with depression and anxiety symptoms.

PubMed

Wenze, Susan J; Gunthert, Kathleen C; German, Ramaris E

2012-07-01

The authors used experience sampling to investigate biases in affective forecasting and recall in individuals with varying levels of depression and anxiety symptoms. Participants who were higher in depression symptoms demonstrated stronger (more pessimistic) negative mood prediction biases, marginally stronger negative mood recall biases, and weaker (less optimistic) positive mood prediction and recall biases. Participants who were higher in anxiety symptoms demonstrated stronger negative mood prediction biases, but positive mood prediction biases that were on par with those who were lower in anxiety. Anxiety symptoms were not associated with mood recall biases. Neither depression symptoms nor anxiety symptoms were associated with bias in event prediction. Their findings fit well with the tripartite model of depression and anxiety. Results are also consistent with the conceptualization of anxiety as a "forward-looking" disorder, and with theories that emphasize the importance of pessimism and general negative information processing in depressive functioning.

Response Conflict and Affective Responses in the Control and Expression of Race Bias

PubMed Central

Bartholow, Bruce D.; Henry, Erika A.

2010-01-01

Models of racial attitudes traditionally have assumed that individual differences in the strength of underlying, ‘implicit’ associations between racial categories and stereotypical traits are the primary determinant of the expression of race bias. Thus, individual differences in performance on laboratory tasks designed to assess implicit race bias tend to be interpreted in terms of association strength. Here, we argue that such associations tell only part of the story, and probably the least interesting part. We posit that response conflict and its regulation are critical to understanding the need for control, and that affect-related processes help to determine the extent to which control resources will be implemented to overcome biased associations. We present data from a number of recent behavioral and psychophysiological studies in support of this idea, as well as conceptual accounts that point toward a model of race bias regulation that depends upon processes identified as important for regulation of thought, affect and action more generally. PMID:21278910

Response Conflict and Affective Responses in the Control and Expression of Race Bias.

PubMed

Bartholow, Bruce D; Henry, Erika A

2010-10-01

Models of racial attitudes traditionally have assumed that individual differences in the strength of underlying, 'implicit' associations between racial categories and stereotypical traits are the primary determinant of the expression of race bias. Thus, individual differences in performance on laboratory tasks designed to assess implicit race bias tend to be interpreted in terms of association strength. Here, we argue that such associations tell only part of the story, and probably the least interesting part. We posit that response conflict and its regulation are critical to understanding the need for control, and that affect-related processes help to determine the extent to which control resources will be implemented to overcome biased associations. We present data from a number of recent behavioral and psychophysiological studies in support of this idea, as well as conceptual accounts that point toward a model of race bias regulation that depends upon processes identified as important for regulation of thought, affect and action more generally.

Task relevance of emotional information affects anxiety-linked attention bias in visual search.

PubMed

Dodd, Helen F; Vogt, Julia; Turkileri, Nilgun; Notebaert, Lies

2017-01-01

Task relevance affects emotional attention in healthy individuals. Here, we investigate whether the association between anxiety and attention bias is affected by the task relevance of emotion during an attention task. Participants completed two visual search tasks. In the emotion-irrelevant task, participants were asked to indicate whether a discrepant face in a crowd of neutral, middle-aged faces was old or young. Irrelevant to the task, target faces displayed angry, happy, or neutral expressions. In the emotion-relevant task, participants were asked to indicate whether a discrepant face in a crowd of middle-aged neutral faces was happy or angry (target faces also varied in age). Trait anxiety was not associated with attention in the emotion-relevant task. However, in the emotion-irrelevant task, trait anxiety was associated with a bias for angry over happy faces. These findings demonstrate that the task relevance of emotional information affects conclusions about the presence of an anxiety-linked attention bias. Copyright © 2016 Elsevier B.V. All rights reserved.

Marijuana's acute effects on cognitive bias for affective and marijuana cues.

PubMed

Metrik, Jane; Aston, Elizabeth R; Kahler, Christopher W; Rohsenow, Damaris J; McGeary, John E; Knopik, Valerie S

2015-10-01

Marijuana produces acute increases in positive subjective effects and decreased reactivity to negative affective stimuli, though may also acutely induce anxiety. Implicit attentional and evaluative processes may explicate marijuana's ability to acutely increase positive and negative emotions. This within-subjects study examined whether smoked marijuana with 2.7-3.0% delta-9-tetrahydrocannabinol (THC), relative to placebo, acutely changed attentional processing of rewarding and negative affective stimuli as well as marijuana-specific stimuli. On 2 separate days, regular marijuana users (N = 89) smoked placebo or active THC cigarette and completed subjective ratings of mood, intoxication, urge to smoke marijuana, and 2 experimental tasks: pleasantness rating (response latency and perceived pleasantness of affective and marijuana-related stimuli) and emotional Stroop (attentional bias to affective stimuli). On the pleasantness rating task, active marijuana increased response latency to negatively valenced and marijuana-related (vs. neutral) visual stimuli, beyond a general slowing of response. Active marijuana also increased pleasantness ratings of marijuana images, although to a lesser extent than placebo due to reduced marijuana urge after smoking. Overall, active marijuana did not acutely change processing of positive emotional stimuli. There was no evidence of attentional bias to affective word stimuli on the emotional Stroop task with the exception of attentional bias to positive word stimuli in the subgroup of marijuana users with cannabis dependence. Marijuana may increase allocation of attentional resources toward marijuana-specific and negatively valenced visual stimuli without altering processing of positively valenced stimuli. Marijuana-specific cues may be more attractive with higher levels of marijuana craving and less wanted with low craving levels. (c) 2015 APA, all rights reserved).

Do the affective properties of smoking-related cues influence attentional and approach biases in cigarette smokers?

PubMed

Bradley, B P; Field, M; Healy, H; Mogg, K

2008-09-01

Research indicates that drug-related cues elicit attention and approach biases in drug users. However, attentional biases are not unique to addiction (e.g., they are also found for emotional information). This study examined whether attentional and approach biases in cigarette smokers are mediated by the motivational salience of cues (relevance to drug-taking), rather than by their affective properties (subjective liking of the cues). Cues included pleasant and unpleasant smoking-related pictures. Attentional biases, approach tendencies and subjective evaluation of the cues were assessed on visual probe, stimulus-response compatibility and rating tasks, respectively. Compared with non-smokers, smokers showed a greater attentional bias for both pleasant and unpleasant smoking-related cues presented for 2000 ms, but not for 200 ms. Smokers showed a greater approach bias for unpleasant cues, although the groups did not differ significantly in approach bias for pleasant smoking-related cues. Smokers rated both pleasant and unpleasant smoking pictures more positively than did non-smokers. Results suggest that a bias to maintain attention on smoking-related cues in young adult smokers is primarily a function of drug-relevance, rather than affective properties, of the cues. In contrast, approach tendencies and pleasantness judgements were influenced by drug use, drug-relevance and the affective properties of the cues.

Model-Based Control of Observer Bias for the Analysis of Presence-Only Data in Ecology

PubMed Central

Warton, David I.; Renner, Ian W.; Ramp, Daniel

2013-01-01

Presence-only data, where information is available concerning species presence but not species absence, are subject to bias due to observers being more likely to visit and record sightings at some locations than others (hereafter “observer bias”). In this paper, we describe and evaluate a model-based approach to accounting for observer bias directly – by modelling presence locations as a function of known observer bias variables (such as accessibility variables) in addition to environmental variables, then conditioning on a common level of bias to make predictions of species occurrence free of such observer bias. We implement this idea using point process models with a LASSO penalty, a new presence-only method related to maximum entropy modelling, that implicitly addresses the “pseudo-absence problem” of where to locate pseudo-absences (and how many). The proposed method of bias-correction is evaluated using systematically collected presence/absence data for 62 plant species endemic to the Blue Mountains near Sydney, Australia. It is shown that modelling and controlling for observer bias significantly improves the accuracy of predictions made using presence-only data, and usually improves predictions as compared to pseudo-absence or “inventory” methods of bias correction based on absences from non-target species. Future research will consider the potential for improving the proposed bias-correction approach by estimating the observer bias simultaneously across multiple species. PMID:24260167

Gender bias affects forests worldwide

Treesearch

Marlène Elias; Susan S Hummel; Bimbika S Basnett; Carol J.P. Colfer

2017-01-01

Gender biases persist in forestry research and practice. These biases result in reduced scientific rigor and inequitable, ineffective, and less efficient policies, programs, and interventions. Drawing from a two-volume collection of current and classic analyses on gender in forests, we outline five persistent and inter-related themes: gendered governance, tree tenure,...

Mutational Biases and GC-Biased Gene Conversion Affect GC Content in the Plastomes of Dendrobium Genus

PubMed Central

Niu, Zhitao; Xue, Qingyun; Wang, Hui; Xie, Xuezhu; Zhu, Shuying; Liu, Wei; Ding, Xiaoyu

2017-01-01

The variation of GC content is a key genome feature because it is associated with fundamental elements of genome organization. However, the reason for this variation is still an open question. Different kinds of hypotheses have been proposed to explain the variation of GC content during genome evolution. However, these hypotheses have not been explicitly investigated in whole plastome sequences. Dendrobium is one of the largest genera in the orchid species. Evolutionary studies of the plastomic organization and base composition are limited in this genus. In this study, we obtained the high-quality plastome sequences of D. loddigesii and D. devonianum. The comparison results showed a nearly identical organization in Dendrobium plastomes, indicating that the plastomic organization is highly conserved in Dendrobium genus. Furthermore, the impact of three evolutionary forces—selection, mutational biases, and GC-biased gene conversion (gBGC)—on the variation of GC content in Dendrobium plastomes was evaluated. Our results revealed: (1) consistent GC content evolution trends and mutational biases in single-copy (SC) and inverted repeats (IRs) regions; and (2) that gBGC has influenced the plastome-wide GC content evolution. These results suggest that both mutational biases and gBGC affect GC content in the plastomes of Dendrobium genus. PMID:29099062

Intrapersonal Variability in Negative Affect as a Moderator of Accuracy and Bias in Interpersonal Perception.

PubMed

Sadikaj, Gentiana; Moskowitz, D S; Zuroff, David C

2015-08-01

High intrapersonal variability has frequently been found to be related to poor personal and interpersonal outcomes. Little research has examined processes by which intrapersonal variability influences outcomes. This study explored the relation of intrapersonal variability in negative affect (negative affect flux) to accuracy and bias in the perception of a romantic partner's quarrelsome behavior. A sample of 93 cohabiting couples participated in a study using an event-contingent recording (ECR) methodology in which they reported their negative affect, quarrelsome behavior, and perception of their partner's quarrelsome behavior in interactions with each other during a 20-day period. Negative affect flux was operationalized as the within-person standard deviation of negative affect scores across couple interactions. Findings suggested that participants were both accurate in tracking changes in their partner's quarrelsome behavior and biased in assuming their partner's quarrelsome behavior mirrored their own quarrelsome behavior. Negative affect flux moderated both accuracy and bias of assumed similarity such that participants with higher flux manifested both greater tracking accuracy and larger bias of assumed similarity. Negative affect flux may be related to enhanced vigilance to close others' negative behavior, which may explain higher tracking accuracy and propensity to rely on a person's own negative behavior as a means of judging others' negative behavior. These processes may augment these individuals' negative interpersonal behavior, enhance cycles of negative social interactions, and lead to poor intrapersonal and interpersonal outcomes.

Counter-regulation in affective attentional biases: a basic mechanism that warrants flexibility in emotion and motivation.

PubMed

Rothermund, Klaus; Voss, Andreas; Wentura, Dirk

2008-02-01

We investigated whether anticipating positive or negative future outcomes during goal pursuit has a modulatory effect on attentional biases for affectively congruent and incongruent distractor stimuli. In two experiments using a flanker task, we found that distractor interference of stimuli signaling opportunities or dangers was stronger after inducing an outcome focus of the opposite valence. The second experiment provided additional evidence that the incongruency effect reflects a global shift in affective attentional biases and is not mediated by changes in strategies or in the perceived valence of the stimuli. It is argued that counter-regulation in affective attentional biases serves an important function for the regulation of emotion and action.

Facial affect processing and depression susceptibility: cognitive biases and cognitive neuroscience.

PubMed

Bistricky, Steven L; Ingram, Rick E; Atchley, Ruth Ann

2011-11-01

Facial affect processing is essential to social development and functioning and is particularly relevant to models of depression. Although cognitive and interpersonal theories have long described different pathways to depression, cognitive-interpersonal and evolutionary social risk models of depression focus on the interrelation of interpersonal experience, cognition, and social behavior. We therefore review the burgeoning depressive facial affect processing literature and examine its potential for integrating disciplines, theories, and research. In particular, we evaluate studies in which information processing or cognitive neuroscience paradigms were used to assess facial affect processing in depressed and depression-susceptible populations. Most studies have assessed and supported cognitive models. This research suggests that depressed and depression-vulnerable groups show abnormal facial affect interpretation, attention, and memory, although findings vary based on depression severity, comorbid anxiety, or length of time faces are viewed. Facial affect processing biases appear to correspond with distinct neural activity patterns and increased depressive emotion and thought. Biases typically emerge in depressed moods but are occasionally found in the absence of such moods. Indirect evidence suggests that childhood neglect might cultivate abnormal facial affect processing, which can impede social functioning in ways consistent with cognitive-interpersonal and interpersonal models. However, reviewed studies provide mixed support for the social risk model prediction that depressive states prompt cognitive hypervigilance to social threat information. We recommend prospective interdisciplinary research examining whether facial affect processing abnormalities promote-or are promoted by-depressogenic attachment experiences, negative thinking, and social dysfunction.

Interventions that affect gender bias in hiring: a systematic review.

PubMed

Isaac, Carol; Lee, Barbara; Carnes, Molly

2009-10-01

To systematically review experimental evidence for interventions mitigating gender bias in employment. Unconscious endorsement of gender stereotypes can undermine academic medicine's commitment to gender equity. The authors performed electronic and hand searches for randomized controlled studies since 1973 of interventions that affect gender differences in evaluation of job applicants. Twenty-seven studies met all inclusion criteria. Interventions fell into three categories: application information, applicant features, and rating conditions. The studies identified gender bias as the difference in ratings or perceptions of men and women with identical qualifications. Studies reaffirmed negative bias against women being evaluated for positions traditionally or predominantly held by men (male sex-typed jobs). The assessments of male and female raters rarely differed. Interventions that provided raters with clear evidence of job-relevant competencies were effective. However, clearly competent women were rated lower than equivalent men for male sex-typed jobs unless evidence of communal qualities was also provided. A commitment to the value of credentials before review of applicants and women's presence at above 25% of the applicant pool eliminated bias against women. Two studies found unconscious resistance to "antibias" training, which could be overcome with distraction or an intervening task. Explicit employment equity policies and an attractive appearance benefited men more than women, whereas repeated employment gaps were more detrimental to men. Masculine-scented perfume favored the hiring of both sexes. Negative bias occurred against women who expressed anger or who were perceived as self-promoting. High-level evidence exists for strategies to mitigate gender bias in hiring.

Interventions That Affect Gender Bias in Hiring: A Systematic Review

PubMed Central

Isaac, Carol; Lee, Barbara; Carnes, Molly

2015-01-01

Purpose To systematically review experimental evidence for interventions mitigating gender bias in employment. Unconscious endorsement of gender stereotypes can undermine academic medicine's commitment to gender equity. Method The authors performed electronic and hand searches for randomized controlled studies since 1973 of interventions that affect gender differences in evaluation of job applicants. Twenty-seven studies met all inclusion criteria. Interventions fell into three categories: application information, applicant features, and rating conditions. Results The studies identified gender bias as the difference in ratings or perceptions of men and women with identical qualifications. Studies reaffirmed negative bias against women being evaluated for positions traditionally or predominantly held by men (male sex-typed jobs). The assessments of male and female raters rarely differed. Interventions that provided raters with clear evidence of job-relevant competencies were effective. However, clearly competent women were rated lower than equivalent men for male sex-typed jobs unless evidence of communal qualities was also provided. A commitment to the value of credentials before review of applicants and women's presence at above 25% of the applicant pool eliminated bias against women. Two studies found unconscious resistance to “antibias” training, which could be overcome with distraction or an intervening task. Explicit employment equity policies and an attractive appearance benefited men more than women, whereas repeated employment gaps were more detrimental to men. Masculine-scented perfume favored the hiring of both sexes. Negative bias occurred against women who expressed anger or who were perceived as self-promoting. Conclusions High-level evidence exists for strategies to mitigate gender bias in hiring. PMID:19881440

Bias against research on gender bias.

PubMed

Cislak, Aleksandra; Formanowicz, Magdalena; Saguy, Tamar

2018-01-01

The bias against women in academia is a documented phenomenon that has had detrimental consequences, not only for women, but also for the quality of science. First, gender bias in academia affects female scientists, resulting in their underrepresentation in academic institutions, particularly in higher ranks. The second type of gender bias in science relates to some findings applying only to male participants, which produces biased knowledge. Here, we identify a third potentially powerful source of gender bias in academia: the bias against research on gender bias. In a bibliometric investigation covering a broad range of social sciences, we analyzed published articles on gender bias and race bias and established that articles on gender bias are funded less often and published in journals with a lower Impact Factor than articles on comparable instances of social discrimination. This result suggests the possibility of an underappreciation of the phenomenon of gender bias and related research within the academic community. Addressing this meta-bias is crucial for the further examination of gender inequality, which severely affects many women across the world.

Observational Evidence for the Effect of Amplification Bias in Gravitational Microlensing Experiments

NASA Astrophysics Data System (ADS)

Han, Cheongho; Jeong, Youngjin; Kim, Ho-Il

1998-11-01

Recently Alard, Mao, & Guibert and Alard proposed to detect the shift of a star's image centroid, δx, as a method to identify the lensed source among blended stars. Goldberg & Woźniak actually applied this method to the OGLE-1 database and found that seven of 15 events showed significant centroid shifts of δx >~ 0.2". The amount of centroid shift has been estimated theoretically by Goldberg; however, he treated the problem in general and did not apply it to a particular survey or field and therefore based his estimate on simple toy model luminosity functions (i.e., power laws). In this paper, we construct the expected distribution of δx for Galactic bulge events based on the precise stellar luminosity function observed by Holtzman et al. using the Hubble Space Telescope. Their luminosity function is complete up to MI ~ 9.0 (MV ~ 12), which corresponds to faint M-type stars. In our analysis we find that regular blending cannot produce a large fraction of events with measurable centroid shifts. By contrast, a significant fraction of events would have measurable centroid shifts if they are affected by amplification-bias blending. Therefore, the measurements of large centroid shifts for an important fraction of microlensing events of Goldberg & Woźniak confirm the prediction of Han & Alard that a large fraction of Galactic bulge events are affected by amplification-bias blending.

Understanding and Avoiding Immortal-Time Bias in Gastrointestinal Observational Research.

PubMed

Targownik, Laura E; Suissa, Samy

2015-12-01

Pharmacoepidemiologic analyses, in which observational data is interrogated to evaluate relationships between patterns of drug use and both beneficial and adverse outcomes, are being increasingly used in the study of inflammatory bowel disease. However, the results of many of these analyses may be corrupted by the presence of immortal person-time bias, an analytic error which can result in an overestimation of the benefits of medical therapy. In this report, we will describe immortal person-time bias, explain the mechanism through which it confers a false benefit, and guide the reader in how to identify this source of bias in the medical literature.

Marijuana’s Acute Effects on Cognitive Bias for Affective and Marijuana Cues

PubMed Central

Metrik, Jane; Aston, Elizabeth R.; Kahler, Christopher W.; Rohsenow, Damaris J.; McGeary, John E.; Knopik, Valerie S.

2015-01-01

Marijuana produces acute increases in positive subjective effects and decreased reactivity to negative affective stimuli, though may also acutely induce anxiety. Implicit attentional and evaluative processes may explicate marijuana’s ability to acutely increase positive and negative emotions. This within-subjects study examined whether smoked marijuana with 2.7–3.0 % delta-9-tetrahydrocannabinol (THC), relative to placebo, acutely changed attentional processing of rewarding and negative affective stimuli as well as marijuana-specific stimuli. On two separate days, regular marijuana users (N=89) smoked placebo or active THC cigarette and completed subjective ratings of mood, intoxication, urge to smoke marijuana, and two experimental tasks: Pleasantness Rating (response latency and perceived pleasantness of affective and marijuana-related stimuli) and Emotional Stroop (attentional bias to affective stimuli). On the Pleasantness Rating task, active marijuana increased response latency to negatively-valenced and marijuana-related (vs. neutral) visual stimuli, beyond a general slowing of response. Active marijuana also increased pleasantness ratings of marijuana images, although to a lesser extent than placebo due to reduced marijuana urge after smoking. Overall, active marijuana did not acutely change processing of positive emotional stimuli. There was no evidence of attentional bias to affective word stimuli on the Emotional Stroop task with the exception of attentional bias to positive word stimuli in the subgroup of marijuana users with cannabis dependence. Marijuana may increase allocation of attentional resources towards marijuana-specific and negatively-valenced visual stimuli without altering processing of positively-valenced stimuli. Marijuana-specific cues may be more attractive with higher levels of marijuana craving and less wanted with low craving levels. PMID:26167716

Personality traits affecting judgement bias task performance in dogs (Canis familiaris).

PubMed

Barnard, Shanis; Wells, Deborah L; Milligan, Adam D S; Arnott, Gareth; Hepper, Peter G

2018-04-27

Certain personality traits (e.g. anxiousness, fearfulness), are known to affect the cognitive processing of environmental stimuli, such as the judgement of ambiguous stimuli (judgement bias). Our aim was to assess if personality traits are predictive of a more or less 'pessimistic' or 'optimistic' judgement bias in the domestic dog. We assessed dog personality (N = 31) using two validated protocols: the Dog Mentality Assessment (standardised battery test) and the CBARQ (owner-based survey). We used a common task based on the animals' latency to approach a bowl placed in one of three ambiguous positions (Near Positive, Middle, Near Negative) between a baited (Positive) and a non-baited food bowl (Negative) to assess judgement bias. Linear Mixed Model analyses revealed that dogs scoring higher on sociability, excitability and non-social-fear had shorter response latencies to bowls in an ambiguous location, indicating a more 'optimistic' bias. In contrast, dogs scoring higher on separation-related-behaviour and dog-directed-fear/aggression traits were more likely to judge an ambiguous stimulus as leading to a negative outcome, indicating a more 'pessimistic' bias. Results, partially consistent with previous findings in humans, indicate that personality plays a role in the cognitive processing of environmental stimuli in the domestic dog.

Two roads diverged: Distinct mechanisms of attentional bias differentially predict negative affect and persistent negative thought.

PubMed

Onie, Sandersan; Most, Steven B

2017-08-01

Attentional biases to threatening stimuli have been implicated in various emotional disorders. Theoretical approaches often carry the implicit assumption that various attentional bias measures tap into the same underlying construct, but attention itself is not a unitary mechanism. Most attentional bias tasks-such as the dot probe (DP)-index spatial attention, neglecting other potential attention mechanisms. We compared the DP with emotion-induced blindness (EIB), which appears to be mechanistically distinct, and examined the degree to which these tasks predicted (a) negative affect, (b) persistent negative thought (i.e., worry, rumination), and (c) each other. The 2 tasks did not predict each other, and they uniquely accounted for negative affect in a regression analysis. The relationship between EIB and negative affect was mediated by persistent negative thought, whereas that between the DP and negative affect was not, suggesting that EIB may be more intimately linked than spatial attention with persistent negative thought. Experiment 2 revealed EIB to have a favorable test-retest reliability. Together, these findings underscore the importance of distinguishing between attentional bias mechanisms when constructing theoretical models of, and interventions that target, particular emotional disorders. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Overcorrection for Social-Categorization Information Moderates Impact Bias in Affective Forecasting.

PubMed

Lau, Tatiana; Morewedge, Carey K; Cikara, Mina

2016-10-01

Plural societies require individuals to forecast how others-both in-group and out-group members-will respond to gains and setbacks. Typically, correcting affective forecasts to include more relevant information improves their accuracy by reducing their extremity. In contrast, we found that providing affective forecasters with social-category information about their targets made their forecasts more extreme and therefore less accurate. In both political and sports contexts, forecasters across five experiments exhibited greater impact bias for both in-group and out-group members (e.g., a Democrat or Republican) than for unspecified targets when predicting experiencers' responses to positive and negative events. Inducing time pressure reduced the extremity of forecasts for group-labeled but not unspecified targets, which suggests that the increased impact bias was due to overcorrection for social-category information, not different intuitive predictions for identified targets. Finally, overcorrection was better accounted for by stereotypes than by spontaneous retrieval of extreme group exemplars.

Partial verification bias and incorporation bias affected accuracy estimates of diagnostic studies for biomarkers that were part of an existing composite gold standard.

PubMed

Karch, Annika; Koch, Armin; Zapf, Antonia; Zerr, Inga; Karch, André

2016-10-01

To investigate how choice of gold standard biases estimates of sensitivity and specificity in studies reassessing the diagnostic accuracy of biomarkers that are already part of a lifetime composite gold standard (CGS). We performed a simulation study based on the real-life example of the biomarker "protein 14-3-3" used for diagnosing Creutzfeldt-Jakob disease. Three different types of gold standard were compared: perfect gold standard "autopsy" (available in a small fraction only; prone to partial verification bias), lifetime CGS (including the biomarker under investigation; prone to incorporation bias), and "best available" gold standard (autopsy if available, otherwise CGS). Sensitivity was unbiased when comparing 14-3-3 with autopsy but overestimated when using CGS or "best available" gold standard. Specificity of 14-3-3 was underestimated in scenarios comparing 14-3-3 with autopsy (up to 24%). In contrast, overestimation (up to 20%) was observed for specificity compared with CGS; this could be reduced to 0-10% when using the "best available" gold standard. Choice of gold standard affects considerably estimates of diagnostic accuracy. Using the "best available" gold standard (autopsy where available, otherwise CGS) leads to valid estimates of specificity, whereas sensitivity is estimated best when tested against autopsy alone. Copyright © 2016 Elsevier Inc. All rights reserved.

Threat processing in generalized social phobia: an investigation of interpretation biases in ambiguous facial affect.

PubMed

Jusyte, Aiste; Schönenberg, Michael

2014-06-30

Facial affect is one of the most important information sources during the course of social interactions, but it is susceptible to distortion due to the complex and dynamic nature. Socially anxious individuals have been shown to exhibit alterations in the processing of social information, such as an attentional and interpretative bias toward threatening information. This may be one of the key factors contributing to the development and maintenance of anxious psychopathology. The aim of the current study was to investigate whether a threat-related interpretation bias is evident for ambiguous facial stimuli in a population of individuals with a generalized Social Anxiety Disorder (gSAD) as compared to healthy controls. Participants judged ambiguous happy/fearful, angry/fearful and angry/happy blends varying in intensity and rated the predominant affective expression. The results obtained in this study do not indicate that gSAD is associated with a biased interpretation of ambiguous facial affect. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Affective health bias in older adults: Considering positive and negative affect in a general health context.

PubMed

Whitehead, Brenda R; Bergeman, C S

2016-09-01

Because subjective health reports are a primary source of health information in a number of medical and research-based contexts, much research has been devoted to establishing the extent to which these self-reports of health correspond to health information from more objective sources. One of the key factors considered in this area is trait affect, with most studies emphasizing the impact of negative affect (negative emotions) over positive affect (positive emotions), and focusing on high-arousal affect (e.g., anger, excitement) over moderate- or low-arousal affect (e.g., relaxed, depressed). The present study examines the impact of both Positive and Negative Affect (PA/NA)-measured by items of both high and low arousal-on the correspondence between objective health information and subjective health reports. Another limitation of existing literature in the area is the focus on samples suffering from a particular diagnosis or on specific symptom reports; here, these effects are investigated in a sample of community-dwelling older adults representing a broader spectrum of health. 153 older adults (Mage = 71.2) took surveys assessing Perceived Health and Affect and underwent an objective physical health assessment. Structural equation modeling was used to investigate the extent to which the relationship between Objective Health and Perceived Health was moderated by PA or NA, which would indicate the presence of affective health bias. Results reveal a significant moderation effect for NA, but not for PA; PA appeared to serve a more mediational function, indicating that NA and PA operate on health perceptions in distinct ways. These findings provide evidence that in our high-functioning, community-dwelling sample of older adults, a) affective health bias is present within a general health context, and not only within specific symptom or diagnostic categories; and b) that both PA and NA play important roles in the process. Copyright © 2016 Elsevier Ltd. All rights

Using selection bias to explain the observed structure of Internet diffusions

PubMed Central

Golub, Benjamin; Jackson, Matthew O.

2010-01-01

Recently, large datasets stored on the Internet have enabled the analysis of processes, such as large-scale diffusions of information, at new levels of detail. In a recent study, Liben-Nowell and Kleinberg [(2008) Proc Natl Acad Sci USA 105:4633–4638] observed that the flow of information on the Internet exhibits surprising patterns whereby a chain letter reaches its typical recipient through long paths of hundreds of intermediaries. We show that a basic Galton–Watson epidemic model combined with the selection bias of observing only large diffusions suffices to explain these patterns. Thus, selection biases of which data we observe can radically change the estimation of classical diffusion processes. PMID:20534439

Land Surface Model Biases and their Impacts on the Assimilation of Snow-related Observations

NASA Astrophysics Data System (ADS)

Arsenault, K. R.; Kumar, S.; Hunter, S. M.; Aman, R.; Houser, P. R.; Toll, D.; Engman, T.; Nigro, J.

2007-12-01

Some recent snow modeling studies have employed a wide range of assimilation methods to incorporate snow cover or other snow-related observations into different hydrological or land surface models. These methods often include taking both model and observation biases into account throughout the model integration. This study focuses more on diagnosing the model biases and presenting their subsequent impacts on assimilating snow observations and modeled snowmelt processes. In this study, the land surface model, the Community Land Model (CLM), is used within the Land Information System (LIS) modeling framework to show how such biases impact the assimilation of MODIS snow cover observations. Alternative in-situ and satellite-based observations are used to help guide the CLM LSM in better predicting snowpack conditions and more realistic timing of snowmelt for a western US mountainous region. Also, MODIS snow cover observation biases will be discussed, and validation results will be provided. The issues faced with inserting or assimilating MODIS snow cover at moderate spatial resolutions (like 1km or less) will be addressed, and the impacts on CLM will be presented.

Asymmetric bias in perception of facial affect among Roman and Arabic script readers.

PubMed

Heath, Robin L; Rouhana, Aida; Ghanem, Dana Abi

2005-01-01

The asymmetric chimeric faces test is used frequently as an indicator of right hemisphere involvement in the perception of facial affect, as the test is considered free of linguistic elements. Much of the original research with the asymmetric chimeric faces test was conducted with subjects reading left-to-right Roman script, i.e., English. As readers of right-to-left scripts, such as Arabic, demonstrated a mixed or weak rightward bias in judgements of facial affect, the influence of habitual scanning direction was thought to intersect with laterality. We administered the asymmetric chimeric faces test to 1239 adults who represented a range of script experience, i.e., Roman script readers (English and French), Arabic readers, bidirectional readers of Roman and Arabic scripts, and illiterates. Our findings supported the hypothesis that the bias in facial affect judgement is rooted in laterality, but can be influenced by script direction. Specifically, right-handed readers of Roman script demonstrated the greatest mean leftward score, and mixed-handed Arabic script readers demonstrated the greatest mean rightward score. Biliterates showed a gradual shift in asymmetric perception, as their scores fell between those of Roman and Arabic script readers, basically distributed in the order expected by their handedness and most often used script. Illiterates, whose only directional influence was laterality, showed a slight leftward bias.

Sex differences in affective responses to homoerotic stimuli: evidence for an unconscious bias among heterosexual men, but not heterosexual women.

PubMed

Mahaffey, Amanda L; Bryan, Angela; Hutchison, Kent E

2005-10-01

Antigay bias is a well-documented social problem among heterosexual men, though heterosexual women display a lesser tendency toward this bias. Startle eye blink has been established as a valid measure of the affective component of antigay bias in heterosexual men. In the current study, a sample of 91 heterosexual women and 87 heterosexual men were exposed to a variety of sexual photographic stimuli accompanied by startle probes. Heterosexual men who expressed more bias against gay men using a social distance measure (i.e., discomfort with being in close quarters with a gay man) displayed a startle response consistent with greater negative affect (e.g., fear and disgust) toward gay male stimuli, while those with less self-reported antigay bias did not display a physiological bias against gay men, and none of these men showed a relationship between bias against lesbians and physiological responses while viewing lesbian images. There were no such physiological manifestations of antigay bias in heterosexual women while viewing lesbian or gay male images, even among those who self-reported such bias. It appears that heterosexual women do not tend to have the same affective response toward homosexuals that some heterosexual men experience.

Measuring Attitudes That Bias Teacher Observation.

ERIC Educational Resources Information Center

Marston, Paul T.; Clements, Richard O.

It was hypothesized that individual differences in observer attitudes might affect the way observers code teacher behavior. A questionnaire assessing educational attitudes was given to 22 subjects who were trained on 3 classroom observation systems: the Flanders Interaction Analysis, the Classroom Observation Scales, and the Classroom Observation…

Simultaneous Estimation of Model State Variables and Observation and Forecast Biases Using a Two-Stage Hybrid Kalman Filter

NASA Technical Reports Server (NTRS)

Pauwels, V. R. N.; DeLannoy, G. J. M.; Hendricks Franssen, H.-J.; Vereecken, H.

2013-01-01

In this paper, we present a two-stage hybrid Kalman filter to estimate both observation and forecast bias in hydrologic models, in addition to state variables. The biases are estimated using the discrete Kalman filter, and the state variables using the ensemble Kalman filter. A key issue in this multi-component assimilation scheme is the exact partitioning of the difference between observation and forecasts into state, forecast bias and observation bias updates. Here, the error covariances of the forecast bias and the unbiased states are calculated as constant fractions of the biased state error covariance, and the observation bias error covariance is a function of the observation prediction error covariance. In a series of synthetic experiments, focusing on the assimilation of discharge into a rainfall-runoff model, it is shown that both static and dynamic observation and forecast biases can be successfully estimated. The results indicate a strong improvement in the estimation of the state variables and resulting discharge as opposed to the use of a bias-unaware ensemble Kalman filter. Furthermore, minimal code modification in existing data assimilation software is needed to implement the method. The results suggest that a better performance of data assimilation methods should be possible if both forecast and observation biases are taken into account.

The future in clinical genetics: affective forecasting biases in patient and clinician decision making.

PubMed

Peters, S A; Laham, S M; Pachter, N; Winship, I M

2014-04-01

When clinicians facilitate and patients make decisions about predictive genetic testing, they often base their choices on the predicted emotional consequences of positive and negative test results. Research from psychology and decision making suggests that such predictions may often be biased. Work on affective forecasting-predicting one's future emotional states-shows that people tend to overestimate the impact of (especially negative) emotional events on their well-being; a phenomenon termed the impact bias. In this article, we review the causes and consequences of the impact bias in medical decision making, with a focus on applying such findings to predictive testing in clinical genetics. We also recommend strategies for reducing the impact bias and consider the ethical and practical implications of doing so. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Immortal time bias in observational studies of time-to-event outcomes.

PubMed

Jones, Mark; Fowler, Robert

2016-12-01

The purpose of the study is to show, through simulation and example, the magnitude and direction of immortal time bias when an inappropriate analysis is used. We compare 4 methods of analysis for observational studies of time-to-event outcomes: logistic regression, standard Cox model, landmark analysis, and time-dependent Cox model using an example data set of patients critically ill with influenza and a simulation study. For the example data set, logistic regression, standard Cox model, and landmark analysis all showed some evidence that treatment with oseltamivir provides protection from mortality in patients critically ill with influenza. However, when the time-dependent nature of treatment exposure is taken account of using a time-dependent Cox model, there is no longer evidence of a protective effect of treatment. The simulation study showed that, under various scenarios, the time-dependent Cox model consistently provides unbiased treatment effect estimates, whereas standard Cox model leads to bias in favor of treatment. Logistic regression and landmark analysis may also lead to bias. To minimize the risk of immortal time bias in observational studies of survival outcomes, we strongly suggest time-dependent exposures be included as time-dependent variables in hazard-based analyses. Copyright © 2016 Elsevier Inc. All rights reserved.

Intrinsic scatter of caustic masses and hydrostatic bias: An observational study

NASA Astrophysics Data System (ADS)

Andreon, S.; Trinchieri, G.; Moretti, A.; Wang, J.

2017-10-01

All estimates of cluster mass have some intrinsic scatter and perhaps some bias with true mass even in the absence of measurement errors for example caused by cluster triaxiality and large scale structure. Knowledge of the bias and scatter values is fundamental for both cluster cosmology and astrophysics. In this paper we show that the intrinsic scatter of a mass proxy can be constrained by measurements of the gas fraction because masses with higher values of intrinsic scatter with true mass produce more scattered gas fractions. Moreover, the relative bias of two mass estimates can be constrained by comparing the mean gas fraction at the same (nominal) cluster mass. Our observational study addresses the scatter between caustic (I.e., dynamically estimated) and true masses, and the relative bias of caustic and hydrostatic masses. For these purposes, we used the X-ray Unbiased Cluster Sample, a cluster sample selected independently from the intracluster medium content with reliable masses: 34 galaxy clusters in the nearby (0.050 < z < 0.135) Universe, mostly with 14 < log M500/M⊙ ≲ 14.5, and with caustic masses. We found a 35% scatter between caustic and true masses. Furthermore, we found that the relative bias between caustic and hydrostatic masses is small, 0.06 ± 0.05 dex, improving upon past measurements. The small scatter found confirms our previous measurements of a highly variable amount of feedback from cluster to cluster, which is the cause of the observed large variety of core-excised X-ray luminosities and gas masses.

The Effects of Oncologist Implicit Racial Bias in Racially Discordant Oncology Interactions

PubMed Central

Dovidio, John F.; Gonzalez, Richard; Albrecht, Terrance L.; Chapman, Robert; Foster, Tanina; Harper, Felicity W.K.; Hagiwara, Nao; Hamel, Lauren M.; Shields, Anthony F.; Gadgeel, Shirish; Simon, Michael S.; Griggs, Jennifer J.; Eggly, Susan

2016-01-01

Purpose Health providers’ implicit racial bias negatively affects communication and patient reactions to many medical interactions. However, its effects on racially discordant oncology interactions are largely unknown. Thus, we examined whether oncologist implicit racial bias has similar effects in oncology interactions. We further investigated whether oncologist implicit bias negatively affects patients’ perceptions of recommended treatments (i.e., degree of confidence, expected difficulty). We predicted oncologist implicit bias would negatively affect communication, patient reactions to interactions, and, indirectly, patient perceptions of recommended treatments. Methods Participants were 18 non-black medical oncologists and 112 black patients. Oncologists completed an implicit racial bias measure several weeks before video-recorded treatment discussions with new patients. Observers rated oncologist communication and recorded interaction length of time and amount of time oncologists and patients spoke. Following interactions, patients answered questions about oncologists’ patient-centeredness and difficulty remembering contents of the interaction, distress, trust, and treatment perceptions. Results As predicted, oncologists higher in implicit racial bias had shorter interactions, and patients and observers rated these oncologists’ communication as less patient-centered and supportive. Higher implicit bias also was associated with more patient difficulty remembering contents of the interaction. In addition, oncologist implicit bias indirectly predicted less patient confidence in recommended treatments, and greater perceived difficulty completing them, through its impact on oncologists’ communication (as rated by both patients and observers). Conclusion Oncologist implicit racial bias is negatively associated with oncologist communication, patients’ reactions to racially discordant oncology interactions, and patient perceptions of recommended treatments

A double-observer method for reducing bias in faecal pellet surveys of forest ungulates

USGS Publications Warehouse

Jenkins, K.J.; Manly, B.F.J.

2008-01-01

1. Faecal surveys are used widely to study variations in abundance and distribution of forest-dwelling mammals when direct enumeration is not feasible. The utility of faecal indices of abundance is limited, however, by observational bias and variation in faecal disappearance rates that obscure their relationship to population size. We developed methods to reduce variability in faecal surveys and improve reliability of faecal indices. 2. We used double-observer transect sampling to estimate observational bias of faecal surveys of Roosevelt elk Cervus elaphus roosevelti and Columbian black-tailed deer Odocoileus hemionus columbianus in Olympic National Park, Washington, USA. We also modelled differences in counts of faecal groups obtained from paired cleared and uncleared transect segments as a means to adjust standing crop faecal counts for a standard accumulation interval and to reduce bias resulting from variable decay rates. 3. Estimated detection probabilities of faecal groups ranged from < 0.2-1.0 depending upon the observer, whether the faecal group was from elk or deer, faecal group size, distance of the faecal group from the sampling transect, ground vegetation cover, and the interaction between faecal group size and distance from the transect. 4. Models of plot-clearing effects indicated that standing crop counts of deer faecal groups required 34% reduction on flat terrain and 53% reduction on sloping terrain to represent faeces accumulated over a standard 100-day interval, whereas counts of elk faecal groups required 0% and 46% reductions on flat and sloping terrain, respectively. 5. Synthesis and applications. Double-observer transect sampling provides a cost-effective means of reducing observational bias and variation in faecal decay rates that obscure the interpretation of faecal indices of large mammal abundance. Given the variation we observed in observational bias of faecal surveys and persistence of faeces, we emphasize the need for future

A pancultural perspective on the fading affect bias in autobiographical memory.

PubMed

Ritchie, Timothy D; Batteson, Tamzin J; Bohn, Annette; Crawford, Matthew T; Ferguson, Georgie V; Schrauf, Robert W; Vogl, Rodney J; Walker, W Richard

2015-01-01

The fading affect bias (FAB) refers to the negative affect associated with autobiographical events fading faster than the positive affect associated with such events, a reliable and valid valence effect established by researchers in the USA. The present study examined the idea that the FAB is a ubiquitous emotion regulating phenomenon in autobiographical memory that is present in people from a variety of cultures. We tested for evidence of the FAB by sampling more than 2400 autobiographical event descriptions from 562 participants in 10 cultures around the world. Using variations on a common method, each sample evidenced a FAB: positive affect faded slower than negative affect did. Results suggest that in tandem with local norms and customs, the FAB may foster recovery from negative life events and promote the retention of the positive emotions, within and outside of the USA. We discuss these findings in the context of Keltner and Haidt's levels of analysis theory of emotion and culture.

Impaired cognition and decision-making in bipolar depression but no 'affective bias' evident.

PubMed

Rubinsztein, J S; Michael, A; Underwood, B R; Tempest, M; Sahakian, B J

2006-05-01

Depression is usually the predominant affective state in bipolar disorder. There are few studies, with discrepant views, examining the extent of cognitive impairment in patients with bipolar depression. To our knowledge, there are no previous studies examining decision-making ability or whether there is an affective attentional bias in bipolar depression. We ascertained 24 depressed bipolar I patients from acute psychiatric hospital wards and out-patient clinics and 26 age- and IQ-matched healthy controls. Using computerized tests we evaluated their performance on 'neutral' (non-emotional) cognitive tasks (i.e. memory, attention and executive function) and on novel tasks of emotional cognition (i.e. the decision-making task and the affective go/no-go task). Accuracy measures were significantly impaired on tests of visual and spatial recognition and attentional set-shifting in bipolar depression compared with age- and IQ-matched controls. The quality of decision-making was also significantly impaired in the patients. A mood-congruent attentional bias for 'sad' targets was not evident on the affective go/no-go task. We found widespread evidence of significant cognitive impairment and impaired quality of decision-making in symptomatically severe depressed bipolar patients. This cognitive impairment may contribute to difficulties with daily living, decision-making and the ability to engage and comply with psychological and drug treatments.

The Importance of Covariate Selection in Controlling for Selection Bias in Observational Studies

ERIC Educational Resources Information Center

Steiner, Peter M.; Cook, Thomas D.; Shadish, William R.; Clark, M. H.

2010-01-01

The assumption of strongly ignorable treatment assignment is required for eliminating selection bias in observational studies. To meet this assumption, researchers often rely on a strategy of selecting covariates that they think will control for selection bias. Theory indicates that the most important covariates are those highly correlated with…

Conditioned social dominance threat: observation of others’ social dominance biases threat learning

PubMed Central

Molapour, Tanaz; Olsson, Andreas

2016-01-01

Social groups are organized along dominance hierarchies, which determine how we respond to threats posed by dominant and subordinate others. The persuasive impact of these dominance threats on mental and physical well-being has been well described but it is unknown how dominance rank of others bias our experience and learning in the first place. We introduce a model of conditioned social dominance threat in humans, where the presence of a dominant other is paired with an aversive event. Participants first learned about the dominance rank of others by observing their dyadic confrontations. During subsequent fear learning, the dominant and subordinate others were equally predictive of an aversive consequence (mild electric shock) to the participant. In three separate experiments, we show that participants’ eye-blink startle responses and amygdala reactivity adaptively tracked dominance of others during observation of confrontation. Importantly, during fear learning dominant vs subordinate others elicited stronger and more persistent learned threat responses as measured by physiological arousal and amygdala activity. Our results characterize the neural basis of learning through observing conflicts between others, and how this affects subsequent learning through direct, personal experiences. PMID:27217107

Information bias in health research: definition, pitfalls, and adjustment methods

PubMed Central

Althubaiti, Alaa

2016-01-01

As with other fields, medical sciences are subject to different sources of bias. While understanding sources of bias is a key element for drawing valid conclusions, bias in health research continues to be a very sensitive issue that can affect the focus and outcome of investigations. Information bias, otherwise known as misclassification, is one of the most common sources of bias that affects the validity of health research. It originates from the approach that is utilized to obtain or confirm study measurements. This paper seeks to raise awareness of information bias in observational and experimental research study designs as well as to enrich discussions concerning bias problems. Specifying the types of bias can be essential to limit its effects and, the use of adjustment methods might serve to improve clinical evaluation and health care practice. PMID:27217764

Fully correcting the meteor speed distribution for radar observing biases

NASA Astrophysics Data System (ADS)

Moorhead, Althea V.; Brown, Peter G.; Campbell-Brown, Margaret D.; Heynen, Denis; Cooke, William J.

2017-09-01

Meteor radars such as the Canadian Meteor Orbit Radar (CMOR) have the ability to detect millions of meteors, making it possible to study the meteoroid environment in great detail. However, meteor radars also suffer from a number of detection biases; these biases must be fully corrected for in order to derive an accurate description of the meteoroid population. We present a bias correction method for patrol radars that accounts for the full form of ionization efficiency and mass distribution. This is an improvement over previous methods such as that of Taylor (1995), which requires power-law distributions for ionization efficiency and a single mass index. We apply this method to the meteor speed distribution observed by CMOR and find a significant enhancement of slow meteors compared to earlier treatments. However, when the data set is severely restricted to include only meteors with very small uncertainties in speed, the fraction of slow meteors is substantially reduced, indicating that speed uncertainties must be carefully handled.

Bias to pollen odors is affected by early exposure and foraging experience.

PubMed

Arenas, A; Farina, W M

2014-07-01

In many pollinating insects, foraging preferences are adjusted on the basis of floral cues learned at the foraging site. In addition, olfactory experiences gained at early adult stages might also help them to initially choose food sources. To understand pollen search behavior of honeybees, we studied how responses elicited by pollen-based odors are biased in foraging-age workers according to (i) their genetic predisposition to collect pollen, (ii) pollen related information gained during foraging and (iii) different experiences with pollen gained at early adult ages. Bees returning to the hive carrying pollen loads, were strongly biased to unfamiliar pollen bouquets when tested in a food choice device against pure odors. Moreover, pollen foragers' orientation response was specific to the odors emitted by the pollen type they were carrying on their baskets, which suggests that foragers retrieve pollen odor information to recognize rewarding flowers outside the hive. We observed that attraction to pollen odor was mediated by the exposure to a pollen diet during the first week of life. We did not observe the same attraction in foraging-age bees early exposed to an artificial diet that did not contain pollen. Contrary to the specific response observed to cues acquired during foraging, early exposure to single-pollen diets did not bias orientation response towards a specific pollen odor in foraging-age bees (i.e. bees chose equally between the exposed and the novel monofloral pollen odors). Our results show that pollen exposure at early ages together with olfactory experiences gained in a foraging context are both relevant to bias honeybees' pollen search behavior. Copyright © 2014 Elsevier Ltd. All rights reserved.

Final Sampling Bias in Haptic Judgments: How Final Touch Affects Decision-Making.

PubMed

Mitsuda, Takashi; Yoshioka, Yuichi

2018-01-01

When people make a choice between multiple items, they usually evaluate each item one after the other repeatedly. The effect of the order and number of evaluating items on one's choices is essential to understanding the decision-making process. Previous studies have shown that when people choose a favorable item from two items, they tend to choose the item that they evaluated last. This tendency has been observed regardless of sensory modalities. This study investigated the origin of this bias by using three experiments involving two-alternative forced-choice tasks using handkerchiefs. First, the bias appeared in a smoothness discrimination task, which indicates that the bias was not based on judgments of preference. Second, the handkerchief that was touched more often tended to be chosen more frequently in the preference task, but not in the smoothness discrimination task, indicating that a mere exposure effect enhanced the bias. Third, in the condition where the number of touches did not differ between handkerchiefs, the bias appeared when people touched a handkerchief they wanted to touch last, but not when people touched the handkerchief that was predetermined. This finding suggests a direct coupling between final voluntary touching and judgment.

The Effects of Oncologist Implicit Racial Bias in Racially Discordant Oncology Interactions.

PubMed

Penner, Louis A; Dovidio, John F; Gonzalez, Richard; Albrecht, Terrance L; Chapman, Robert; Foster, Tanina; Harper, Felicity W K; Hagiwara, Nao; Hamel, Lauren M; Shields, Anthony F; Gadgeel, Shirish; Simon, Michael S; Griggs, Jennifer J; Eggly, Susan

2016-08-20

Health providers' implicit racial bias negatively affects communication and patient reactions to many medical interactions. However, its effects on racially discordant oncology interactions are largely unknown. Thus, we examined whether oncologist implicit racial bias has similar effects in oncology interactions. We further investigated whether oncologist implicit bias negatively affects patients' perceptions of recommended treatments (i.e., degree of confidence, expected difficulty). We predicted oncologist implicit bias would negatively affect communication, patient reactions to interactions, and, indirectly, patient perceptions of recommended treatments. Participants were 18 non-black medical oncologists and 112 black patients. Oncologists completed an implicit racial bias measure several weeks before video-recorded treatment discussions with new patients. Observers rated oncologist communication and recorded interaction length of time and amount of time oncologists and patients spoke. Following interactions, patients answered questions about oncologists' patient-centeredness and difficulty remembering contents of the interaction, distress, trust, and treatment perceptions. As predicted, oncologists higher in implicit racial bias had shorter interactions, and patients and observers rated these oncologists' communication as less patient-centered and supportive. Higher implicit bias also was associated with more patient difficulty remembering contents of the interaction. In addition, oncologist implicit bias indirectly predicted less patient confidence in recommended treatments, and greater perceived difficulty completing them, through its impact on oncologists' communication (as rated by both patients and observers). Oncologist implicit racial bias is negatively associated with oncologist communication, patients' reactions to racially discordant oncology interactions, and patient perceptions of recommended treatments. These perceptions could subsequently directly

Space-based IR tracking bias removal using background star observations

NASA Astrophysics Data System (ADS)

Clemons, T. M., III; Chang, K. C.

2009-05-01

This paper provides the results of a proposed methodology for removing sensor bias from a space-based infrared (IR) tracking system through the use of stars detected in the background field of the tracking sensor. The tracking system consists of two satellites flying in a lead-follower formation tracking a ballistic target. Each satellite is equipped with a narrow-view IR sensor that provides azimuth and elevation to the target. The tracking problem is made more difficult due to a constant, non-varying or slowly varying bias error present in each sensor's line of sight measurements. As known stars are detected during the target tracking process, the instantaneous sensor pointing error can be calculated as the difference between star detection reading and the known position of the star. The system then utilizes a separate bias filter to estimate the bias value based on these detections and correct the target line of sight measurements to improve the target state vector. The target state vector is estimated through a Linearized Kalman Filter (LKF) for the highly non-linear problem of tracking a ballistic missile. Scenarios are created using Satellite Toolkit(C) for trajectories with associated sensor observations. Mean Square Error results are given for tracking during the period when the target is in view of the satellite IR sensors. The results of this research provide a potential solution to bias correction while simultaneously tracking a target.

Development of pile foundation bias factors using observed behavior of platforms during Hurricane Andrew

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

Aggarwal, R.K.; Litton, R.W.; Cornell, C.A.

1996-12-31

The performance of more than 3,000 offshore platforms in the Gulf of Mexico was observed during the passage of Hurricane Andrew in August 1992. This event provided an opportunity to test the procedures used for platform analysis and design. A global bias was inferred for overall platform capacity and loads in the Andrew Joint Industry Project (JIP) Phase 1. It was predicted that the pile foundations of several platforms should have failed, but did not. These results indicated that the biases specific to foundation failure modes may be higher than those of jacket failure modes. The biases in predictions ofmore » foundation failure modes were therefore investigated further in this study. The work included capacity analysis and calibration of predictions with the observed behavior for 3 jacket platforms and 3 caissons using Bayesian updating. Bias factors for two foundation failure modes, lateral shear and overturning, were determined for each structure. Foundation capacity estimates using conventional methods were found to be conservatively biased overall.« less

Observer Bias: An Interaction of Temperament Traits with Biases in the Semantic Perception of Lexical Material

PubMed Central

Trofimova, Ira

2014-01-01

The lexical approach is a method in differential psychology that uses people's estimations of verbal descriptors of human behavior in order to derive the structure of human individuality. The validity of the assumptions of this method about the objectivity of people's estimations is rarely questioned. Meanwhile the social nature of language and the presence of emotionality biases in cognition are well-recognized in psychology. A question remains, however, as to whether such an emotionality-capacities bias is strong enough to affect semantic perception of verbal material. For the lexical approach to be valid as a method of scientific investigations, such biases should not exist in semantic perception of the verbal material that is used by this approach. This article reports on two studies investigating differences between groups contrasted by 12 temperament traits (i.e. by energetic and other capacities, as well as emotionality) in the semantic perception of very general verbal material. Both studies contrasted the groups by a variety of capacities: endurance, lability and emotionality separately in physical, social-verbal and mental aspects of activities. Hypotheses of “background emotionality” and a “projection through capacities” were supported. Non-evaluative criteria for categorization (related to complexity, organization, stability and probability of occurrence of objects) followed the polarity of evaluative criteria, and did not show independence from this polarity. Participants with stronger physical or social endurance gave significantly more positive ratings to a variety of concepts, and participants with faster physical tempo gave more positive ratings to timing-related concepts. The results suggest that people's estimations of lexical material related to human behavior have emotionality, language- and dynamical capacities-related biases and therefore are unreliable. This questions the validity of the lexical approach as a method for the objective

Biases and systematics in the observational derivation of galaxy properties: comparing different techniques on synthetic observations of simulated galaxies

NASA Astrophysics Data System (ADS)

Guidi, Giovanni; Scannapieco, Cecilia; Walcher, C. Jakob

2015-12-01

We study the sources of biases and systematics in the derivation of galaxy properties from observational studies, focusing on stellar masses, star formation rates, gas and stellar metallicities, stellar ages, magnitudes and colours. We use hydrodynamical cosmological simulations of galaxy formation, for which the real quantities are known, and apply observational techniques to derive the observables. We also analyse biases that are relevant for a proper comparison between simulations and observations. For our study, we post-process the simulation outputs to calculate the galaxies' spectral energy distributions (SEDs) using stellar population synthesis models and also generate the fully consistent far-UV-submillimetre wavelength SEDs with the radiative transfer code SUNRISE. We compared the direct results of simulations with the observationally derived quantities obtained in various ways, and found that systematic differences in all studied galaxy properties appear, which are caused by: (1) purely observational biases, (2) the use of mass-weighted and luminosity-weighted quantities, with preferential sampling of more massive and luminous regions, (3) the different ways of constructing the template of models when a fit to the spectra is performed, and (4) variations due to different calibrations, most notably for gas metallicities and star formation rates. Our results show that large differences can appear depending on the technique used to derive galaxy properties. Understanding these differences is of primary importance both for simulators, to allow a better judgement of similarities and differences with observations, and for observers, to allow a proper interpretation of the data.

Hindsight bias and outcome bias in the social construction of medical negligence: a review.

PubMed

Hugh, Thomas B; Dekker, Sidney W A

2009-05-01

Medical negligence has been the subject of much public debate in recent decades. Although the steep increase in the frequency and size of claims against doctors at the end of the last century appears to have plateaued, in Australia at least, medical indemnity costs and consequences are still a matter of concern for doctors, medical defence organisations and governments in most developed countries. Imprecision in the legal definition of negligence opens the possibility that judgments of this issue at several levels may be subject to hindsight and outcome bias. Hindsight bias relates to the probability of an adverse event perceived by a retrospective observer ("I would have known it was going to happen"), while outcome bias is a largely subconscious cognitive distortion produced by the observer's knowledge of the adverse outcome. This review examines the relevant legal, medical, psychological and sociological literature on the operation of these pervasive and universal biases in the retrospective evaluation of adverse events. A finding of medical negligence is essentially an after-the-event social construction and is invariably affected by hindsight bias and knowledge of the adverse outcome. Such biases obviously pose a threat to the fairness of judgments. A number of debiasing strategies have been suggested but are relatively ineffective because of the universality and strength of these biases and the inherent difficulty of concealing from expert witnesses knowledge of the outcome. Education about the effect of the biases is therefore important for lawyers, medical expert witnesses and the judiciary.

A Nonlinear Spacecraft Attitude Controller and Observer with an Unknown Constant Gyro Bias and Gyro Noise

NASA Technical Reports Server (NTRS)

Deutschmann, Julie; Sanner, Robert M.

2001-01-01

A nonlinear control scheme for attitude control of a spacecraft is combined with a nonlinear gyro bias observer for the case of constant gyro bias, in the presence of gyro noise. The observer bias estimates converge exponentially to a mean square bound determined by the standard deviation of the gyro noise. The resulting coupled, closed loop dynamics are proven to be globally stable, with asymptotic tracking which is also mean square bounded. A simulation of the proposed observer-controller design is given for a rigid spacecraft tracking a specified, time-varying attitude sequence to illustrate the theoretical claims.

Towards identification of relevant variables in the observed aerosol optical depth bias between MODIS and AERONET observations

NASA Astrophysics Data System (ADS)

Malakar, N. K.; Lary, D. J.; Gencaga, D.; Albayrak, A.; Wei, J.

2013-08-01

Measurements made by satellite remote sensing, Moderate Resolution Imaging Spectroradiometer (MODIS), and globally distributed Aerosol Robotic Network (AERONET) are compared. Comparison of the two datasets measurements for aerosol optical depth values show that there are biases between the two data products. In this paper, we present a general framework towards identifying relevant set of variables responsible for the observed bias. We present a general framework to identify the possible factors influencing the bias, which might be associated with the measurement conditions such as the solar and sensor zenith angles, the solar and sensor azimuth, scattering angles, and surface reflectivity at the various measured wavelengths, etc. Specifically, we performed analysis for remote sensing Aqua-Land data set, and used machine learning technique, neural network in this case, to perform multivariate regression between the ground-truth and the training data sets. Finally, we used mutual information between the observed and the predicted values as the measure of similarity to identify the most relevant set of variables. The search is brute force method as we have to consider all possible combinations. The computations involves a huge number crunching exercise, and we implemented it by writing a job-parallel program.

Conditioned social dominance threat: observation of others' social dominance biases threat learning.

PubMed

Haaker, Jan; Molapour, Tanaz; Olsson, Andreas

2016-10-01

Social groups are organized along dominance hierarchies, which determine how we respond to threats posed by dominant and subordinate others. The persuasive impact of these dominance threats on mental and physical well-being has been well described but it is unknown how dominance rank of others bias our experience and learning in the first place. We introduce a model of conditioned social dominance threat in humans, where the presence of a dominant other is paired with an aversive event. Participants first learned about the dominance rank of others by observing their dyadic confrontations. During subsequent fear learning, the dominant and subordinate others were equally predictive of an aversive consequence (mild electric shock) to the participant. In three separate experiments, we show that participants' eye-blink startle responses and amygdala reactivity adaptively tracked dominance of others during observation of confrontation. Importantly, during fear learning dominant vs subordinate others elicited stronger and more persistent learned threat responses as measured by physiological arousal and amygdala activity. Our results characterize the neural basis of learning through observing conflicts between others, and how this affects subsequent learning through direct, personal experiences. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Associations among Negative Parenting, Attention Bias to Anger, and Social Anxiety among Youth

PubMed Central

Gulley, Lauren; Oppenheimer, Caroline; Hankin, Benjamin

2014-01-01

Theories of affective learning suggest that early experiences contribute to emotional disorders by influencing the development of processing biases for negative emotional stimuli. Although studies show that physically abused children preferentially attend to angry faces, it is unclear whether youth exposed to more typical aspects of negative parenting would exhibit the same type of bias. The current studies extend previous research by linking observed negative parenting styles (e.g. authoritarian) and behaviors (e.g. criticism and negative affect) to attention bias for angry faces in both a psychiatrically enriched (ages 11–17 years; N = 60) and a general community (ages 9–15 years; N = 75) sample of youth. In addition, the association between observed negative parenting (e.g. authoritarian style and negative affect) and youth social anxiety was mediated by attention bias for angry faces in the general community sample. Overall, findings provide preliminary support for theories of affective learning and risk for psychopathology among youth. PMID:23815705

Associations among negative parenting, attention bias to anger, and social anxiety among youth.

PubMed

Gulley, Lauren D; Oppenheimer, Caroline W; Hankin, Benjamin L

2014-02-01

Theories of affective learning suggest that early experiences contribute to emotional disorders by influencing the development of processing biases for negative emotional stimuli. Although studies have shown that physically abused children preferentially attend to angry faces, it is unclear whether youth exposed to more typical aspects of negative parenting exhibit the same type of bias. The current studies extend previous research by linking observed negative parenting styles (e.g., authoritarian) and behaviors (e.g., criticism and negative affect) to attention bias for angry faces in both a psychiatrically enriched (ages 11-17 years; N = 60) and a general community (ages 9-15 years; N = 75) sample of youth. In addition, the association between observed negative parenting (e.g., authoritarian style and negative affect) and youth social anxiety was mediated by attention bias for angry faces in the general community sample. Overall, findings provide preliminary support for theories of affective learning and risk for psychopathology among youth.

A Judgement Bias Test to Assess Affective State and Potential Therapeutics in a Rat Model of Chemotherapy-Induced Mucositis.

PubMed

George, Rebecca P; Barker, Timothy H; Lymn, Kerry A; Bigatton, Dylan A; Howarth, Gordon S; Whittaker, Alexandra L

2018-05-29

Chemotherapy-induced mucositis is an extremely painful condition that occurs in 40-60% of patients undergoing chemotherapy. As mucositis currently has no effective treatment, and due to the self-limiting nature of the condition, the major treatment aims are to manage symptoms and limit pain with significance placed on improving patient quality of life. Rodent models are frequently used in mucositis research. These investigations typically assess pathological outcomes, yet fail to include a measure of affective state; the key therapeutic goal. Assessment of cognitive biases is a novel approach to determining the affective state of animals. Consequently, this study aimed to validate a cognitive bias test through a judgement bias paradigm to measure affective state in a rat model of chemotherapy-induced intestinal mucositis. Rats with intestinal mucositis demonstrated a negative affective state, which was partially ameliorated by analgesic administration, whilst healthy rats showed an optimistic response. This study concluded that the judgement bias test was able to evaluate the emotional state of rats with chemotherapy-induced mucositis. These findings provide a foundation for future refinement to the experimental design associated with the animal model that will expedite successful transitioning of novel therapeutics to clinical practice, and also improve humane endpoint implementation.

Ethnic bias and clinical decision-making among New Zealand medical students: an observational study.

PubMed

Harris, Ricci; Cormack, Donna; Stanley, James; Curtis, Elana; Jones, Rhys; Lacey, Cameron

2018-01-23

Health professional racial/ethnic bias may impact on clinical decision-making and contribute to subsequent ethnic health inequities. However, limited research has been undertaken among medical students. This paper presents findings from the Bias and Decision-Making in Medicine (BDMM) study, which sought to examine ethnic bias (Māori (indigenous peoples) compared with New Zealand European) among medical students and associations with clinical decision-making. All final year New Zealand (NZ) medical students in 2014 and 2015 (n = 888) were invited to participate in a cross-sectional online study. Key components included: two chronic disease vignettes (cardiovascular disease (CVD) and depression) with randomized patient ethnicity (Māori or NZ European) and questions on patient management; implicit bias measures (an ethnicity preference Implicit Association Test (IAT) and an ethnicity and compliant patient IAT); and, explicit ethnic bias questions. Associations between ethnic bias and clinical decision-making responses to vignettes were tested using linear regression. Three hundred and two students participated (34% response rate). Implicit and explicit ethnic bias favoring NZ Europeans was apparent among medical students. In the CVD vignette, no significant differences in clinical decision-making by patient ethnicity were observed. There were also no differential associations by patient ethnicity between any measures of ethnic bias (implicit or explicit) and patient management responses in the CVD vignette. In the depression vignette, some differences in the ranking of recommended treatment options were observed by patient ethnicity and explicit preference for NZ Europeans was associated with increased reporting that NZ European patients would benefit from treatment but not Māori (slope difference 0.34, 95% CI 0.08, 0.60; p = 0.011), although this was the only significant finding in these analyses. NZ medical students demonstrated ethnic bias, although

Bias modification training can alter approach bias and chocolate consumption.

PubMed

Schumacher, Sophie E; Kemps, Eva; Tiggemann, Marika

2016-01-01

Recent evidence has demonstrated that bias modification training has potential to reduce cognitive biases for attractive targets and affect health behaviours. The present study investigated whether cognitive bias modification training could be applied to reduce approach bias for chocolate and affect subsequent chocolate consumption. A sample of 120 women (18-27 years) were randomly assigned to an approach-chocolate condition or avoid-chocolate condition, in which they were trained to approach or avoid pictorial chocolate stimuli, respectively. Training had the predicted effect on approach bias, such that participants trained to approach chocolate demonstrated an increased approach bias to chocolate stimuli whereas participants trained to avoid such stimuli showed a reduced bias. Further, participants trained to avoid chocolate ate significantly less of a chocolate muffin in a subsequent taste test than participants trained to approach chocolate. Theoretically, results provide support for the dual process model's conceptualisation of consumption as being driven by implicit processes such as approach bias. In practice, approach bias modification may be a useful component of interventions designed to curb the consumption of unhealthy foods. Copyright © 2015 Elsevier Ltd. All rights reserved.

Greek Physical Education Teachers' Gender Biases in Learning and Teaching

ERIC Educational Resources Information Center

Mouratidou, Katerina; Barkoukis, Vassilis

2018-01-01

Gender biases have often been observed in physical education (PE) classes, as many teachers adopt a male-biased perspective in teaching and learning. This might affect their evaluation of students' behavior and may lead students to accept and reproduce gender biases in other social contexts. The aim of this study was to examine whether PE teachers…

Efficient bias correction for magnetic resonance image denoising.

PubMed

Mukherjee, Partha Sarathi; Qiu, Peihua

2013-05-30

Magnetic resonance imaging (MRI) is a popular radiology technique that is used for visualizing detailed internal structure of the body. Observed MRI images are generated by the inverse Fourier transformation from received frequency signals of a magnetic resonance scanner system. Previous research has demonstrated that random noise involved in the observed MRI images can be described adequately by the so-called Rician noise model. Under that model, the observed image intensity at a given pixel is a nonlinear function of the true image intensity and of two independent zero-mean random variables with the same normal distribution. Because of such a complicated noise structure in the observed MRI images, denoised images by conventional denoising methods are usually biased, and the bias could reduce image contrast and negatively affect subsequent image analysis. Therefore, it is important to address the bias issue properly. To this end, several bias-correction procedures have been proposed in the literature. In this paper, we study the Rician noise model and the corresponding bias-correction problem systematically and propose a new and more effective bias-correction formula based on the regression analysis and Monte Carlo simulation. Numerical studies show that our proposed method works well in various applications. Copyright © 2012 John Wiley & Sons, Ltd.

Facilitation or disengagement? Attention bias in facial affect processing after short-term violent video game exposure

PubMed Central

Liu, Yanling; Lan, Haiying; Teng, Zhaojun; Guo, Cheng; Yao, Dezhong

2017-01-01

Previous research has been inconsistent on whether violent video games exert positive and/or negative effects on cognition. In particular, attentional bias in facial affect processing after violent video game exposure continues to be controversial. The aim of the present study was to investigate attentional bias in facial recognition after short term exposure to violent video games and to characterize the neural correlates of this effect. In order to accomplish this, participants were exposed to either neutral or violent video games for 25 min and then event-related potentials (ERPs) were recorded during two emotional search tasks. The first search task assessed attentional facilitation, in which participants were required to identify an emotional face from a crowd of neutral faces. In contrast, the second task measured disengagement, in which participants were required to identify a neutral face from a crowd of emotional faces. Our results found a significant presence of the ERP component, N2pc, during the facilitation task; however, no differences were observed between the two video game groups. This finding does not support a link between attentional facilitation and violent video game exposure. Comparatively, during the disengagement task, N2pc responses were not observed when participants viewed happy faces following violent video game exposure; however, a weak N2pc response was observed after neutral video game exposure. These results provided only inconsistent support for the disengagement hypothesis, suggesting that participants found it difficult to separate a neutral face from a crowd of emotional faces. PMID:28249033

Facilitation or disengagement? Attention bias in facial affect processing after short-term violent video game exposure.

PubMed

Liu, Yanling; Lan, Haiying; Teng, Zhaojun; Guo, Cheng; Yao, Dezhong

2017-01-01

Previous research has been inconsistent on whether violent video games exert positive and/or negative effects on cognition. In particular, attentional bias in facial affect processing after violent video game exposure continues to be controversial. The aim of the present study was to investigate attentional bias in facial recognition after short term exposure to violent video games and to characterize the neural correlates of this effect. In order to accomplish this, participants were exposed to either neutral or violent video games for 25 min and then event-related potentials (ERPs) were recorded during two emotional search tasks. The first search task assessed attentional facilitation, in which participants were required to identify an emotional face from a crowd of neutral faces. In contrast, the second task measured disengagement, in which participants were required to identify a neutral face from a crowd of emotional faces. Our results found a significant presence of the ERP component, N2pc, during the facilitation task; however, no differences were observed between the two video game groups. This finding does not support a link between attentional facilitation and violent video game exposure. Comparatively, during the disengagement task, N2pc responses were not observed when participants viewed happy faces following violent video game exposure; however, a weak N2pc response was observed after neutral video game exposure. These results provided only inconsistent support for the disengagement hypothesis, suggesting that participants found it difficult to separate a neutral face from a crowd of emotional faces.

Obesity bias in training: attitudes, beliefs, and observations among advanced trainees in professional health disciplines.

PubMed

Puhl, Rebecca M; Luedicke, Joerg; Grilo, Carlos M

2014-04-01

This study examined weight bias among students training in health disciplines and its associations with their perceptions about treating patients with obesity, causes of obesity, and observations of weight bias by instructors and peers. Students (N = 107) enrolled in a post-graduate health discipline (Physician Associate, Clinical Psychology, Psychiatric Residency) completed anonymous questionnaires to assess the above variables. Students reported that patients with obesity are a common target of negative attitudes and derogatory humor by peers (63%), health-care providers (65%), and instructors (40%). Although 80% of students felt confident to treat obesity, many reported that patients with obesity lack motivation to make changes (33%), lead to feelings of frustration (36%), and are non-compliant with treatment (36%). Students with higher weight bias expressed greater frustration in these areas. The effect of students' weight bias on expectations for treatment compliance of patients with obesity was partially mediated by beliefs that obesity is caused by behavioral factors. Weight bias is commonly observed by students in health disciplines, who themselves report frustrations and stereotypes about treating patients with obesity. These findings contribute new knowledge about weight bias among students and provide several targets for medical training and education. Copyright © 2013 The Obesity Society.

Obesity Bias in Training: Attitudes, Beliefs, and Observations among Advanced Trainees in Professional Health Disciplines

PubMed Central

Puhl, Rebecca M.; Luedicke, Joerg; Grilo, Carlos M.

2013-01-01

Objective This study examined weight bias among students training in health disciplines and its associations with their perceptions about treating patients with obesity, causes of obesity, and observations of weight bias by instructors and peers. Design and Methods Students (N = 107) enrolled in a post-graduate health discipline (Physician Associate, Clinical Psychology, Psychiatric Residency) completed anonymous questionnaires to assess the above variables. Results Students reported that patients with obesity are a common target of negative attitudes and derogatory humor by peers (63%), health-care providers (65%), and instructors (40%). Although 80% of students felt confident to treat obesity, many reported that patients with obesity lack motivation to make changes (33%), lead to feelings of frustration (36%), and are noncompliant with treatment (36%). Students with higher weight bias expressed greater frustration in these areas. The effect of students’ weight bias on expectations for treatment compliance of patients with obesity was partially mediated by beliefs that obesity is caused by behavioral factors. Conclusions Weight bias is commonly observed by students in health disciplines, who themselves report frustrations and stereotypes about treating patients with obesity. These findings contribute new knowledge about weight bias among students and provide several targets for medical training and education. PMID:24124078

Subliminal cues bias perception of facial affect in patients with social phobia: evidence for enhanced unconscious threat processing

PubMed Central

Jusyte, Aiste; Schönenberg, Michael

2014-01-01

Socially anxious individuals have been shown to exhibit altered processing of facial affect, especially expressions signaling threat. Enhanced unaware processing has been suggested an important mechanism which may give rise to anxious conscious cognition and behavior. This study investigated whether individuals with social anxiety disorder (SAD) are perceptually more vulnerable to the biasing effects of subliminal threat cues compared to healthy controls. In a perceptual judgment task, 23 SAD and 23 matched control participants were asked to rate the affective valence of parametrically manipulated affective expressions ranging from neutral to angry. Each trial was preceded by subliminal presentation of an angry/neutral cue. The SAD group tended to rate target faces as “angry” when the preceding subliminal stimulus was angry vs. neutral, while healthy participants were not biased by the subliminal stimulus presentation. The perceptual bias in SAD was also associated with higher reaction time latencies in the subliminal angry cue condition. The results provide further support for enhanced unconscious threat processing in SAD individuals. The implications for etiology, maintenance, and treatment of SAD are discussed. PMID:25136307

Subliminal cues bias perception of facial affect in patients with social phobia: evidence for enhanced unconscious threat processing.

PubMed

Jusyte, Aiste; Schönenberg, Michael

2014-01-01

Socially anxious individuals have been shown to exhibit altered processing of facial affect, especially expressions signaling threat. Enhanced unaware processing has been suggested an important mechanism which may give rise to anxious conscious cognition and behavior. This study investigated whether individuals with social anxiety disorder (SAD) are perceptually more vulnerable to the biasing effects of subliminal threat cues compared to healthy controls. In a perceptual judgment task, 23 SAD and 23 matched control participants were asked to rate the affective valence of parametrically manipulated affective expressions ranging from neutral to angry. Each trial was preceded by subliminal presentation of an angry/neutral cue. The SAD group tended to rate target faces as "angry" when the preceding subliminal stimulus was angry vs. neutral, while healthy participants were not biased by the subliminal stimulus presentation. The perceptual bias in SAD was also associated with higher reaction time latencies in the subliminal angry cue condition. The results provide further support for enhanced unconscious threat processing in SAD individuals. The implications for etiology, maintenance, and treatment of SAD are discussed.

Current Paranoid Thinking in Patients With Delusions: The Presence of Cognitive-Affective Biases

PubMed Central

Freeman, Daniel

2013-01-01

Background: There has been renewed interest in the influence of affect on psychosis. Psychological research on persecutory delusions ascribes a prominent role to cognitive processes related to negative affect: anxiety leads to the anticipation of threat within paranoia; depressive negative ideas about the self create a sense of vulnerability in which paranoid thoughts flourish; and self-consciousness enhances feelings of the self as a target. The objective of this study was to examine such affective processes in relation to state paranoia in patients with delusions. Methods: 130 patients with delusions in the context of a nonaffective psychosis diagnosis (predominately schizophrenia) were assessed for contemporaneous levels of persecutory ideation on 5 visual analog scales. Measures were taken of anxiety, depression, threat anticipation, interpretation of ambiguity, self-focus, and negative ideas about the self. Results: Of the patients, 85% report paranoid thinking at testing. Symptoms of anxiety and depression were highly prevalent. Current paranoid thinking was associated with anxiety, depression, greater anticipation of threat events, negative interpretations of ambiguous events, a self-focused cognitive style, and negative ideas about the self. Conclusions: The study provides a clear demonstration that a range of emotion-related cognitive biases, each of which could plausibly maintain delusions, are associated with current paranoid thinking in patients with psychosis. We identified biases both in the contents of cognition and in the processing of information. Links between affect and psychosis are central to the understanding of schizophrenia. We conclude that treatment of emotional dysfunction should lead to reductions in current psychotic experiences. PMID:23223342

Current paranoid thinking in patients with delusions: the presence of cognitive-affective biases.

PubMed

Freeman, Daniel; Dunn, Graham; Fowler, David; Bebbington, Paul; Kuipers, Elizabeth; Emsley, Richard; Jolley, Suzanne; Garety, Philippa

2013-11-01

There has been renewed interest in the influence of affect on psychosis. Psychological research on persecutory delusions ascribes a prominent role to cognitive processes related to negative affect: anxiety leads to the anticipation of threat within paranoia; depressive negative ideas about the self create a sense of vulnerability in which paranoid thoughts flourish; and self-consciousness enhances feelings of the self as a target. The objective of this study was to examine such affective processes in relation to state paranoia in patients with delusions. 130 patients with delusions in the context of a nonaffective psychosis diagnosis (predominately schizophrenia) were assessed for contemporaneous levels of persecutory ideation on 5 visual analog scales. Measures were taken of anxiety, depression, threat anticipation, interpretation of ambiguity, self-focus, and negative ideas about the self. Of the patients, 85% report paranoid thinking at testing. Symptoms of anxiety and depression were highly prevalent. Current paranoid thinking was associated with anxiety, depression, greater anticipation of threat events, negative interpretations of ambiguous events, a self-focused cognitive style, and negative ideas about the self. The study provides a clear demonstration that a range of emotion-related cognitive biases, each of which could plausibly maintain delusions, are associated with current paranoid thinking in patients with psychosis. We identified biases both in the contents of cognition and in the processing of information. Links between affect and psychosis are central to the understanding of schizophrenia. We conclude that treatment of emotional dysfunction should lead to reductions in current psychotic experiences.

The facing bias in biological motion perception: Effects of stimulus gender and observer sex.

PubMed

Schouten, Ben; Troje, Nikolaus F; Brooks, Anna; van der Zwan, Rick; Verfaillie, Karl

2010-07-01

Under orthographic projection, biological motion point-light walkers offer no cues to the order of the dots in depth: Views from the front and from the back result in the very same stimulus. Yet observers show a bias toward seeing a walker facing the viewer (Vanrie, Dekeyser, & Verfaillie, 2004). Recently, we reported that this facing bias strongly depends on the gender of the walker (Brooks et al., 2008). The goal of the present study was, first, to examine the robustness of the effect by testing a much larger subject sample and, second, to investigate whether the effect depends on observer sex. Despite the fact that we found a significant effect of figure gender, we clearly failed to replicate the strong effect observed in the original study. We did, however, observe a significant interaction between figure gender and observer sex.

Preference bias of head orientation in choosing between two non-durables.

PubMed

Funaya, Hiroyuki; Shibata, Tomohiro

2015-01-01

The goal of this study is to investigate how customers' gaze, head and body orientations reflect their choices. Although the relationship between human choice and gaze behavior has been well-studied, other behaviors such as head and body are unknown. We conducted a two-alternatives-forced-choice task to examine (1) whether preference bias, i.e., a positional bias in gaze, head and body toward the item that was later chosen, exists in choice, (2) when preference bias is observed and when prediction of the resulting choice becomes possible (3) whether human choice is affected when the body orientations are manipulated. We used real non-durable products (cheap snacks and clothing) on a shopping shelf. The results showed that there was a significant preference bias in head orientation at the beginning 1 s when the subjects stood straight toward the shelf, and that the head orientation was more biased toward the selected item than the gaze and the center of pressure at the ending 1 s. Manipulating body orientation did not affect the result of choice. The preference bias detected by observing the head orientation would be useful in marketing science for predicting customers' choice.

Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling.

PubMed

Biro, Peter A

2013-02-01

Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, 'hidden' trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

The Use of Propensity Scores and Observational Data to Estimate Randomized Controlled Trial Generalizability Bias

PubMed Central

Pressler, Taylor R.; Kaizar, Eloise E.

2014-01-01

While randomized controlled trials (RCT) are considered the “gold standard” for clinical studies, the use of exclusion criteria may impact the external validity of the results. It is unknown whether estimators of effect size are biased by excluding a portion of the target population from enrollment. We propose to use observational data to estimate the bias due to enrollment restrictions, which we term generalizability bias. In this paper we introduce a class of estimators for the generalizability bias and use simulation to study its properties in the presence of non-constant treatment effects. We find the surprising result that our estimators can be unbiased for the true generalizability bias even when all potentially confounding variables are not measured. In addition, our proposed doubly robust estimator performs well even for mis-specified models. PMID:23553373

Neural Correlates of Racial Ingroup Bias in Observing Computer-Animated Social Encounters.

PubMed

Katsumi, Yuta; Dolcos, Sanda

2017-01-01

Despite evidence for the role of group membership in the neural correlates of social cognition, the mechanisms associated with processing non-verbal behaviors displayed by racially ingroup vs. outgroup members remain unclear. Here, 20 Caucasian participants underwent fMRI recording while observing social encounters with ingroup and outgroup characters displaying dynamic and static non-verbal behaviors. Dynamic behaviors included approach and avoidance behaviors, preceded or not by a handshake; both dynamic and static behaviors were followed by participants' ratings. Behaviorally, participants showed bias toward their ingroup members, demonstrated by faster/slower reaction times for evaluating ingroup static/approach behaviors, respectively. At the neural level, despite overall similar responses in the action observation network to ingroup and outgroup encounters, the medial prefrontal cortex showed dissociable activation, possibly reflecting spontaneous processing of ingroup static behaviors and positive evaluations of ingroup approach behaviors. The anterior cingulate and superior frontal cortices also showed sensitivity to race, reflected in coordinated and reduced activation for observing ingroup static behaviors. Finally, the posterior superior temporal sulcus showed uniquely increased activity to observing ingroup handshakes. These findings shed light on the mechanisms of racial ingroup bias in observing social encounters, and have implications for understanding factors related to successful interactions with individuals from diverse backgrounds.

Neural Correlates of Racial Ingroup Bias in Observing Computer-Animated Social Encounters

PubMed Central

Katsumi, Yuta; Dolcos, Sanda

2018-01-01

Despite evidence for the role of group membership in the neural correlates of social cognition, the mechanisms associated with processing non-verbal behaviors displayed by racially ingroup vs. outgroup members remain unclear. Here, 20 Caucasian participants underwent fMRI recording while observing social encounters with ingroup and outgroup characters displaying dynamic and static non-verbal behaviors. Dynamic behaviors included approach and avoidance behaviors, preceded or not by a handshake; both dynamic and static behaviors were followed by participants’ ratings. Behaviorally, participants showed bias toward their ingroup members, demonstrated by faster/slower reaction times for evaluating ingroup static/approach behaviors, respectively. At the neural level, despite overall similar responses in the action observation network to ingroup and outgroup encounters, the medial prefrontal cortex showed dissociable activation, possibly reflecting spontaneous processing of ingroup static behaviors and positive evaluations of ingroup approach behaviors. The anterior cingulate and superior frontal cortices also showed sensitivity to race, reflected in coordinated and reduced activation for observing ingroup static behaviors. Finally, the posterior superior temporal sulcus showed uniquely increased activity to observing ingroup handshakes. These findings shed light on the mechanisms of racial ingroup bias in observing social encounters, and have implications for understanding factors related to successful interactions with individuals from diverse backgrounds. PMID:29354042

A novel method for correcting scanline-observational bias of discontinuity orientation

PubMed Central

Huang, Lei; Tang, Huiming; Tan, Qinwen; Wang, Dingjian; Wang, Liangqing; Ez Eldin, Mutasim A. M.; Li, Changdong; Wu, Qiong

2016-01-01

Scanline observation is known to introduce an angular bias into the probability distribution of orientation in three-dimensional space. In this paper, numerical solutions expressing the functional relationship between the scanline-observational distribution (in one-dimensional space) and the inherent distribution (in three-dimensional space) are derived using probability theory and calculus under the independence hypothesis of dip direction and dip angle. Based on these solutions, a novel method for obtaining the inherent distribution (also for correcting the bias) is proposed, an approach which includes two procedures: 1) Correcting the cumulative probabilities of orientation according to the solutions, and 2) Determining the distribution of the corrected orientations using approximation methods such as the one-sample Kolmogorov-Smirnov test. The inherent distribution corrected by the proposed method can be used for discrete fracture network (DFN) modelling, which is applied to such areas as rockmass stability evaluation, rockmass permeability analysis, rockmass quality calculation and other related fields. To maximize the correction capacity of the proposed method, the observed sample size is suggested through effectiveness tests for different distribution types, dispersions and sample sizes. The performance of the proposed method and the comparison of its correction capacity with existing methods are illustrated with two case studies. PMID:26961249

The Observed Behavior of the Bias in MODIS-retrieved Cloud Droplet Effective Radius through MISR-MODIS Data Fusion

NASA Astrophysics Data System (ADS)

Fu, D.; Di Girolamo, L.; Liang, L.; Zhao, G.

2017-12-01

Listed as one of the Essential Climate Variables by the Global Climate Observing System, the effective radius (Re) of the cloud drop size distribution plays an important role in the energy and water cycles of the Earth system. Re is retrieved from several passive sensors, such as the Moderate Resolution Imaging Spectroradiometer (MODIS), based on a visible and near-infrared bi-spectral technique that had its foundation more than a quarter century ago. This technique makes a wide range of assumptions, including 1-D radiative transfer, assumed single-mode drop size distribution, and cloud horizontal and vertical homogeneity. It is well known that deviations from these assumptions lead to bias in the retrieved Re. Recently, an effort to characterize the bias in MODIS-retrieved Re through MISR-MODIS data fusion revealed biases in the zonal-mean values of MODIS-retrieved Re that varied from 2 to 11 µm, depending on latitude (Liang et al., 2015). Here, in a push towards bias-correction of MODIS-retrieved Re, we further examine the bias with MISR-MODIS data fusion as it relates to other observed cloud properties, such as cloud-top height and the spatial variability of the radiance field, sun-view geometry, and the driving meteorology had from reanalysis data. Our results show interesting relationships in Re bias behavior with these observed properties, revealing that while Re bias do show a certain degree of dependence on some properties, no single property dominates the behavior in MODIS-retrieved Re bias.

Impact of attention biases to threat and effortful control on individual variations in negative affect and social withdrawal in very young children.

PubMed

Cole, Claire E; Zapp, Daniel J; Fettig, Nicole B; Pérez-Edgar, Koraly

2016-01-01

Early temperamental sensitivity may form the basis for the later development of socioemotional maladjustment. In particular, temperamental negative affect places children at risk for the development of anxiety. However, not all children who show negative affect go on to develop anxiety or extreme social withdrawal. Recent research indicates that reactive control, in the form of attention to threat, may serve as a bridge between early temperament and the development of later social difficulties. In addition, variation in effortful control may also modulate this trajectory. Children (mean age=5.57 years) were assessed for attention bias to threatening and pleasant faces using a dot-probe paradigm. Attention bias to threatening (but not happy) faces moderated the direct positive relation between negative affect and social withdrawal. Children with threat biases showed a significant link between negative affect and social withdrawal, whereas children who avoided threat did not. In contrast, effortful control did not moderate the relation between negative affect and social withdrawal. Rather, there was a direct negative relation between effortful control and social withdrawal. The findings from this short report indicate that the relations among temperament, attention bias, and social withdrawal appears early in life and point to early emerging specificity in reactive and regulatory functioning. Copyright © 2015 Elsevier Inc. All rights reserved.

Impact of Attention Biases to Threat and Effortful Control on Individual Variations in Negative Affect and Social Withdrawal in Very Young Children

PubMed Central

Zapp, Daniel J.; Fettig, Nicole B.; Pérez-Edgar, Koraly

2015-01-01

Early temperamental sensitivity may form the basis for the later development of socioemotional maladjustment. In particular, temperamental negative affect places children at risk for the development of anxiety. However, not all children who show negative affect go on to develop anxiety or extreme social withdrawal. Recent research indicates that reactive control, in the form of attention to threat, may serve as a bridge between early temperament and the development of later social difficulties. In addition, variation in effortful control may also modulate this trajectory. Children (MeanAge=5.57 years) were assessed for attention bias to threatening and pleasant faces using a dot-probe paradigm. Attention bias to threatening (but not happy) faces moderated the direct positive relation between negative affect and social withdrawal. Children with threat biases showed a significant link between negative affect and social withdrawal, while children who avoided threat did not. In contrast, effortful control did not moderate the relation between negative affect and social withdrawal. Rather, there was a direct negative relation between effortful control and social withdrawal. The findings from this short report indicate that the relation amongst temperament, attention bias, and social withdrawal appears early in life and point to early emerging specificity in reactive and regulatory functioning. PMID:26477597

Explication of Interspousal Criticality Bias

PubMed Central

Peterson, Kristina M.; Smith, David A.; Windle, Chaunce R.

2009-01-01

Although bias towards perceiving spousal criticism is related to dysphoria and marital discord (Smith & Peterson, 2008), the bias construct has received insufficient elaboration. We explicated the criticality bias construct by exploring its correlates and incremental validity relative to perceived criticism, marital attributions, and negative affect. 118 couples completed self-report measures and undertook a videotaped discussion task. Signal detection analyses of both spouses’ and outside observers’ ratings of discussions produced bias indices. Criticality bias evidenced a pattern of convergent and discriminant validity mirroring perceived criticism’s (Renshaw, 2008). Bias also provided incremental validity beyond perceived criticism, marital attributions, and negative affect to the prediction of behavior. Bias may be a dysfunctional way to view marital events and a stress generation process. PMID:19286167

On the relative independence of thinking biases and cognitive ability.

PubMed

Stanovich, Keith E; West, Richard F

2008-04-01

In 7 different studies, the authors observed that a large number of thinking biases are uncorrelated with cognitive ability. These thinking biases include some of the most classic and well-studied biases in the heuristics and biases literature, including the conjunction effect, framing effects, anchoring effects, outcome bias, base-rate neglect, "less is more" effects, affect biases, omission bias, myside bias, sunk-cost effect, and certainty effects that violate the axioms of expected utility theory. In a further experiment, the authors nonetheless showed that cognitive ability does correlate with the tendency to avoid some rational thinking biases, specifically the tendency to display denominator neglect, probability matching rather than maximizing, belief bias, and matching bias on the 4-card selection task. The authors present a framework for predicting when cognitive ability will and will not correlate with a rational thinking tendency. (c) 2008 APA, all rights reserved.

Analysis of biases from parallel observations of co-located manual and automatic weather stations in Indonesia

NASA Astrophysics Data System (ADS)

Sopaheluwakan, Ardhasena; Fajariana, Yuaning; Satyaningsih, Ratna; Aprilina, Kharisma; Astuti Nuraini, Tri; Ummiyatul Badriyah, Imelda; Lukita Sari, Dyah; Haryoko, Urip

2017-04-01

Inhomogeneities are often found in long records of climate data. These can occur because of various reasons, among others such as relocation of observation site, changes in observation method, and the transition to automated instruments. Changes to these automated systems are inevitable, and it is taking place worldwide in many of the National Meteorological Services. However this shift of observational practice must be done cautiously and a sufficient period of parallel observation of co-located manual and automated systems should take place as suggested by the World Meteorological Organization. With a sufficient parallel observation period, biases between the two systems can be analyzed. In this study we analyze the biases of a yearlong parallel observation of manual and automatic weather stations in 30 locations in Indonesia. The location of the sites spans from east to west of approximately 45 longitudinal degrees covering different climate characteristics and geographical settings. We study measurements taken by both sensors for temperature and rainfall parameters. We found that the biases from both systems vary from place to place and are more dependent to the setting of the instrument rather than to the climatic and geographical factors. For instance, daytime observations of the automatic weather stations are found to be consistently higher than the manual observation, and vice versa night time observations of the automatic weather stations are lower than the manual observation.

Racial bias in neural empathic responses to pain.

PubMed

Contreras-Huerta, Luis Sebastian; Baker, Katharine S; Reynolds, Katherine J; Batalha, Luisa; Cunnington, Ross

2013-01-01

Recent studies have shown that perceiving the pain of others activates brain regions in the observer associated with both somatosensory and affective-motivational aspects of pain, principally involving regions of the anterior cingulate and anterior insula cortex. The degree of these empathic neural responses is modulated by racial bias, such that stronger neural activation is elicited by observing pain in people of the same racial group compared with people of another racial group. The aim of the present study was to examine whether a more general social group category, other than race, could similarly modulate neural empathic responses and perhaps account for the apparent racial bias reported in previous studies. Using a minimal group paradigm, we assigned participants to one of two mixed-race teams. We use the term race to refer to the Chinese or Caucasian appearance of faces and whether the ethnic group represented was the same or different from the appearance of the participant' own face. Using fMRI, we measured neural empathic responses as participants observed members of their own group or other group, and members of their own race or other race, receiving either painful or non-painful touch. Participants showed clear group biases, with no significant effect of race, on behavioral measures of implicit (affective priming) and explicit group identification. Neural responses to observed pain in the anterior cingulate cortex, insula cortex, and somatosensory areas showed significantly greater activation when observing pain in own-race compared with other-race individuals, with no significant effect of minimal groups. These results suggest that racial bias in neural empathic responses is not influenced by minimal forms of group categorization, despite the clear association participants showed with in-group more than out-group members. We suggest that race may be an automatic and unconscious mechanism that drives the initial neural responses to observed pain in

Racial Bias in Neural Empathic Responses to Pain

PubMed Central

Contreras-Huerta, Luis Sebastian; Baker, Katharine S.; Reynolds, Katherine J.; Batalha, Luisa; Cunnington, Ross

2013-01-01

Recent studies have shown that perceiving the pain of others activates brain regions in the observer associated with both somatosensory and affective-motivational aspects of pain, principally involving regions of the anterior cingulate and anterior insula cortex. The degree of these empathic neural responses is modulated by racial bias, such that stronger neural activation is elicited by observing pain in people of the same racial group compared with people of another racial group. The aim of the present study was to examine whether a more general social group category, other than race, could similarly modulate neural empathic responses and perhaps account for the apparent racial bias reported in previous studies. Using a minimal group paradigm, we assigned participants to one of two mixed-race teams. We use the term race to refer to the Chinese or Caucasian appearance of faces and whether the ethnic group represented was the same or different from the appearance of the participant' own face. Using fMRI, we measured neural empathic responses as participants observed members of their own group or other group, and members of their own race or other race, receiving either painful or non-painful touch. Participants showed clear group biases, with no significant effect of race, on behavioral measures of implicit (affective priming) and explicit group identification. Neural responses to observed pain in the anterior cingulate cortex, insula cortex, and somatosensory areas showed significantly greater activation when observing pain in own-race compared with other-race individuals, with no significant effect of minimal groups. These results suggest that racial bias in neural empathic responses is not influenced by minimal forms of group categorization, despite the clear association participants showed with in-group more than out-group members. We suggest that race may be an automatic and unconscious mechanism that drives the initial neural responses to observed pain in

Immortal time bias in observational studies of drug effects in pregnancy.

PubMed

Matok, Ilan; Azoulay, Laurent; Yin, Hui; Suissa, Samy

2014-09-01

The use of decongestants during the second or third trimesters of pregnancy has been associated with a decreased risk of preterm delivery in two observational studies. This effect may have been subject to immortal time bias, a bias arising from the improper classification of exposure during follow-up. We illustrate this bias by repeating the studies using a different data source. The United Kingdom Hospital Episodes Statistics and the Clinical Practice Research Datalink databases were linked to identify all live singleton pregnancies among women aged 15 to 45 years between 1997 and 2012. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals of preterm delivery (before 37 weeks of gestation) by considering the use of decongestants during the third trimester as a time-fixed (biased analysis which misclassifies unexposed person-time as exposed person-time) and time-varying exposure (unbiased analysis with proper classification of unexposed person-time). All models were adjusted for maternal age, smoking status, maternal diabetes, maternal hypertension, preeclampsia, and parity. Of the 195,582 singleton deliveries, 10,248 (5.2%) were born preterm. In the time-fixed analysis, the HR of preterm delivery for the use of decongestants was below the null and suggestive of a 46% decreased risk (adjusted HR = 0.54; 95% confidence interval, 0.24-1.20). In contrast, the HR was closer to null (adjusted HR = 0.93 95% confidence interval, 0.42-2.06) when the use of decongestants was treated as a time-varying variable. Studies of drug safety in pregnancy should use the appropriate statistical techniques to avoid immortal time bias, particularly when the exposure occurs at later stages of pregnancy. © 2014 Wiley Periodicals, Inc.

The Presentation Location of the Reference Stimuli Affects the Left-Side Bias in the Processing of Faces and Chinese Characters

PubMed Central

Li, Chenglin; Cao, Xiaohua

2017-01-01

For faces and Chinese characters, a left-side processing bias, in which observers rely more heavily on information conveyed by the left side of stimuli than the right side of stimuli, has been frequently reported in previous studies. However, it remains unclear whether this left-side bias effect is modulated by the reference stimuli's location. The present study adopted the chimeric stimuli task to investigate the influence of the presentation location of the reference stimuli on the left-side bias in face and Chinese character processing. The results demonstrated that when a reference face was presented in the left visual field of its chimeric images, which are centrally presented, the participants showed a preference higher than the no-bias threshold for the left chimeric face; this effect, however, was not observed in the right visual field. This finding indicates that the left-side bias effect in face processing is stronger when the reference face is in the left visual field. In contrast, the left-side bias was observed in Chinese character processing when the reference Chinese character was presented in either the left or right visual field. Together, these findings suggest that although faces and Chinese characters both have a left-side processing bias, the underlying neural mechanisms of this left-side bias might be different. PMID:29018391

The Presentation Location of the Reference Stimuli Affects the Left-Side Bias in the Processing of Faces and Chinese Characters.

PubMed

Li, Chenglin; Cao, Xiaohua

2017-01-01

For faces and Chinese characters, a left-side processing bias, in which observers rely more heavily on information conveyed by the left side of stimuli than the right side of stimuli, has been frequently reported in previous studies. However, it remains unclear whether this left-side bias effect is modulated by the reference stimuli's location. The present study adopted the chimeric stimuli task to investigate the influence of the presentation location of the reference stimuli on the left-side bias in face and Chinese character processing. The results demonstrated that when a reference face was presented in the left visual field of its chimeric images, which are centrally presented, the participants showed a preference higher than the no-bias threshold for the left chimeric face; this effect, however, was not observed in the right visual field. This finding indicates that the left-side bias effect in face processing is stronger when the reference face is in the left visual field. In contrast, the left-side bias was observed in Chinese character processing when the reference Chinese character was presented in either the left or right visual field. Together, these findings suggest that although faces and Chinese characters both have a left-side processing bias, the underlying neural mechanisms of this left-side bias might be different.

Housing conditions affect rat responses to two types of ambiguity in a reward–reward discrimination cognitive bias task

PubMed Central

Parker, Richard M.A.; Paul, Elizabeth S.; Burman, Oliver H.P.; Browne, William J.; Mendl, Michael

2014-01-01

Decision-making under ambiguity in cognitive bias tasks is a promising new indicator of affective valence in animals. Rat studies support the hypothesis that animals in a negative affective state evaluate ambiguous cues negatively. Prior automated operant go/go judgement bias tasks have involved training rats that an auditory cue of one frequency predicts a Reward and a cue of a different frequency predicts a Punisher (RP task), and then measuring whether ambiguous cues of intermediate frequency are judged as predicting reward (‘optimism’) or punishment (‘pessimism’). We investigated whether an automated Reward–Reward (RR) task yielded similar results to, and was faster to train than, RP tasks. We also introduced a new ambiguity test (simultaneous presentation of the two training cues) alongside the standard single ambiguous cue test. Half of the rats experienced an unpredictable housing treatment (UHT) designed to induce a negative state. Control rats were relatively ‘pessimistic’, whilst UHT rats were quicker, but no less accurate, in their responses in the RR test, and showed less anxiety-like behaviour in independent tests. A possible reason for these findings is that rats adapted to and were stimulated by UHT, whilst control rats in a predictable environment were more sensitive to novelty and change. Responses in the new ambiguity test correlated positively with those in single ambiguous cue tests, and may provide a measure of attention bias. The RR task was quicker to train than previous automated RP tasks. Together, they could be used to disentangle how reward and punishment processes underpin affect-induced cognitive biases. PMID:25106739

The role of the (111) texture on the exchange bias and interlayer coupling effects observed in sputtered NiFe/IrMn/Co trilayers

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

Castro, I. L.; Nascimento, V. P.; Passamani, E. C.

2013-05-28

Magnetic properties of sputtered NiFe/IrMn/Co trilayers grown on different seed layers (Cu or Ta) deposited on Si (100) substrates were investigated by magnetometry and ferromagnetic resonance measurements. Exchange bias effect and magnetic spring behavior have been studied by changing the IrMn thickness. As shown by X-ray diffraction, Ta and Cu seed layers provoke different degrees of (111) fcc-texture that directly affect the exchange bias and indirectly modify the exchange spring coupling behavior. Increasing the IrMn thickness, it was observed that the coupling angle between the Co and NiFe ferromagnetic layers increases for the Cu seed system, but it reduces formore » the Ta case. The results were explained considering (i) different anisotropies of the Co and IrMn layers induced by the different degree of the (111) texture and (ii) the distinct exchange bias set at the NiFe/IrMn and IrMn/Co interfaces in both systems. The NiFe and Co interlayer coupling angle is strongly correlated with both exchange bias and exchange magnetic spring phenomena. It was also shown that the highest exchange bias field occurs when an unstressed L1{sub 2} IrMn structure is stabilized.« less

Biases in Long-term NO2 Averages Inferred from Satellite Observations Due to Cloud Selection Criteria

NASA Technical Reports Server (NTRS)

Geddes, Jeffrey A.; Murphy, Jennifer G.; O'Brien, Jason M.; Celarier, Edward A.

2012-01-01

Retrievals of atmospheric trace gas column densities from space are compromised by the presence of clouds, requiring most studies to exclude observations with significant cloud fractions in the instrument's field of view. Using NO2 observations at three ground stations representing urban, suburban, and rural environments, and tropospheric vertical column densities measured by the Ozone Monitoring Instrument (OMI) over each site, we show that the observations from space represent monthly averaged ground-level pollutant conditions well (R=0.86) under relatively cloud-free conditions. However, by analyzing the ground-level data and applying the OMI cloud fraction as a filter, we show there is a significant bias in long-term averaged NO2 as a result of removing the data during cloudy conditions. For the ground-based sites considered in this study, excluding observations on days when OMI-derived cloud fractions were greater than 0.2 causes 12:00-14:00 mean summer mixing ratios to be underestimated by 12%+/-6%, 20%+/-7%, and 40%+/-10% on average (+/-1 standard deviation) at the urban, suburban, and rural sites respectively. This bias was investigated in particular at the rural site, a region where pollutant transport is the main source of NO2, and where longterm observations of NOy were also available. Evidence of changing photochemical conditions and a correlation between clear skies and the transport of cleaner air masses play key roles in explaining the bias. The magnitude of a bias is expected to vary from site to site depending on meteorology and proximity to NOx sources, and decreases when longer averaging times of ground station data (e.g. 24-h) are used for the comparison.

Fandom Biases Retrospective Judgments Not Perception.

PubMed

Huff, Markus; Papenmeier, Frank; Maurer, Annika E; Meitz, Tino G K; Garsoffky, Bärbel; Schwan, Stephan

2017-02-24

Attitudes and motivations have been shown to affect the processing of visual input, indicating that observers may see a given situation each literally in a different way. Yet, in real-life, processing information in an unbiased manner is considered to be of high adaptive value. Attitudinal and motivational effects were found for attention, characterization, categorization, and memory. On the other hand, for dynamic real-life events, visual processing has been found to be highly synchronous among viewers. Thus, while in a seminal study fandom as a particularly strong case of attitudes did bias judgments of a sports event, it left the question open whether attitudes do bias prior processing stages. Here, we investigated influences of fandom during the live TV broadcasting of the 2013 UEFA-Champions-League Final regarding attention, event segmentation, immediate and delayed cued recall, as well as affect, memory confidence, and retrospective judgments. Even though we replicated biased retrospective judgments, we found that eye-movements, event segmentation, and cued recall were largely similar across both groups of fans. Our findings demonstrate that, while highly involving sports events are interpreted in a fan dependent way, at initial stages they are processed in an unbiased manner.

Fandom Biases Retrospective Judgments Not Perception

PubMed Central

Huff, Markus; Papenmeier, Frank; Maurer, Annika E.; Meitz, Tino G. K.; Garsoffky, Bärbel; Schwan, Stephan

2017-01-01

Attitudes and motivations have been shown to affect the processing of visual input, indicating that observers may see a given situation each literally in a different way. Yet, in real-life, processing information in an unbiased manner is considered to be of high adaptive value. Attitudinal and motivational effects were found for attention, characterization, categorization, and memory. On the other hand, for dynamic real-life events, visual processing has been found to be highly synchronous among viewers. Thus, while in a seminal study fandom as a particularly strong case of attitudes did bias judgments of a sports event, it left the question open whether attitudes do bias prior processing stages. Here, we investigated influences of fandom during the live TV broadcasting of the 2013 UEFA-Champions-League Final regarding attention, event segmentation, immediate and delayed cued recall, as well as affect, memory confidence, and retrospective judgments. Even though we replicated biased retrospective judgments, we found that eye-movements, event segmentation, and cued recall were largely similar across both groups of fans. Our findings demonstrate that, while highly involving sports events are interpreted in a fan dependent way, at initial stages they are processed in an unbiased manner. PMID:28233877

Keep your bias to yourself: How deliberating with differently biased others affects mock-jurors' guilt decisions, perceptions of the defendant, memories, and evidence interpretation.

PubMed

Ruva, Christine L; Guenther, Christina C

2017-10-01

This experiment explored how mock-jurors' (N = 648) guilt decisions, perceptions of the defendant, memories, and evidence interpretation varied as a function of jury type and pretrial publicity (PTP); utilizing a 2 (jury type: pure-PTP vs. mixed-PTP) × 3 (PTP: defendant, victim, and irrelevant) factorial design. Mock-juries (N = 126) were composed of jurors exposed to the same type of PTP (pure-PTP; e.g., defendant-PTP) or different types of PTP (mixed-PTP; e.g., half exposed to defendant-PTP and half to irrelevant-PTP). Before deliberations jurors exposed to defendant-PTP were most likely to vote guilty; while those exposed to victim-PTP were least likely. After deliberations, jury type and PTP affected jurors' guilt decisions. Specifically, jurors deliberating on pure-PTP juries had verdict distributions that closely resembled the predeliberation distributions. The verdict distributions of jurors on mixed-PTP juries suggested that jurors were influenced by those they deliberated with. Jurors not exposed to PTP appeared to incorporate bias from PTP-exposed jurors. Only PTP had significant effects on postdeliberation measures of memory and evidence interpretation. Mediation analyses revealed that evidence interpretation and defendant credibility assessments mediated the effect of PTP on guilt ratings. Taken together these findings suggest that during deliberations PTP bias can spread to jurors not previously exposed to PTP. In addition, juries composed of jurors exposed to different PTP slants, as opposed to a single PTP slant, can result in less biased decisions. Finally, deliberating with others who do not share similar biases may have little, if any, impact on biased evidence interpretation or memory errors. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Towards a more practical attention bias test to assess affective state in sheep

PubMed Central

Doyle, Rebecca E.; Colditz, Ian G.; Belson, Sue; Cronin, Greg M.; Lee, Caroline

2018-01-01

Tests for attention bias potentially offer more rapid assessment of affective state in animals than existing cognitive methods. An attention bias test has previously been developed for sheep and validated as a measure of anxious states. The 3 minute test assessed behavioural responses of sheep in an enclosed arena after brief exposure to the threat of a dog. Experiment 1 of the current study aimed to refine the previously developed method, removing the need for a habituation period and shortening the test duration. Sheep were given either an anxiolytic drug, an anxiogenic drug or a control treatment prior to testing to induce contrasting affective states. Differences in behaviour were found between the treatment groups within the first 45s of the test, indicating the original test duration could be shortened from 180 s. During testing, 36 of 40 animals in the control and anxiolytic groups ate the novel feed offered in the test, indicating it is not necessary to habituate animals to a feed container. Experiment 2 aimed to confirm the responses measured in the test were primarily towards the dog rather than other aspects of the test environment. Sheep exposed to an empty window at the beginning of the test behaved differently to those which were exposed to a dog, indicating sheep behaviour in the test is at least partially a response to the dog. A third group of sheep were also tested with the dog immediately after having small data loggers attached to their necks. Behaviour of these sheep did not differ from the sheep tested without loggers, indicating data logger attachment did not impact their behaviour in the test. In both experiments, treatments did not appear to modify activity (zones crossed), which we propose indicates the test was primarily detecting valence of the affective state rather than arousal. PMID:29293636

Skin-deep diagnosis: affective bias and zebra retreat complicating the diagnosis of systemic sclerosis.

PubMed

Miller, Chad S

2013-01-01

Nearly half of medical errors can be attributed to an error of clinical reasoning or decision making. It is estimated that the correct diagnosis is missed or delayed in between 5% and 14% of acute hospital admissions. Through understanding why and how physicians make these errors, it is hoped that strategies can be developed to decrease the number of these errors. In the present case, a patient presented with dyspnea, gastrointestinal symptoms and weight loss; the diagnosis was initially missed when the treating physicians took mental short cuts and used heuristics as in this case. Heuristics have an inherent bias that can lead to faulty reasoning or conclusions, especially in complex or difficult cases. Affective bias, which is the overinvolvement of emotion in clinical decision making, limited the available information for diagnosis because of the hesitancy to acquire a full history and perform a complete physical examination in this patient. Zebra retreat, another type of bias, is when a rare diagnosis figures prominently on the differential diagnosis but the physician retreats for various reasons. Zebra retreat also factored in the delayed diagnosis. Through the description of these clinical reasoning errors in an actual case, it is hoped that future errors can be prevented or inspiration for additional research in this area will develop.

Hindsight Bias and Outcome-Consistent Thoughts when Observing and Making Service Provider Decisions

ERIC Educational Resources Information Center

Louie, Therese A.

2005-01-01

Two studies examined the relationship between hindsight bias and corresponding open-ended thoughts for decisions in a service provider setting. Perspectives of those observing and making decisions were examined. In study 1, business students who learned the results of a financial advisor's stock purchase showed the traditional hindsight effect…

Observability considerations for multi-sensor and product fusion: Bias, information content, and validation (Invited)

NASA Astrophysics Data System (ADS)

Reid, J. S.; Zhang, J.; Hyer, E. J.; Campbell, J. R.; Christopher, S. A.; Ferrare, R. A.; Leptoukh, G. G.; Stackhouse, P. W.

2009-12-01

With the successful development of many aerosol products from the NASA A-train as well as new operational geostationary and polar orbiting sensors, the scientific community now has a host of new parameters to use in their analyses. The variety and quality of products has reached a point where the community has moved from basic observation-based science to sophisticated multi-component research that addresses the complex atmospheric environment. In order for these satellite data contribute to the science their uncertainty levels must move from semi-quantitative to quantitative. Initial attempts to quantify uncertainties have led to some recent debate in the community as to the efficacy of aerosol products from current and future NASA satellite sensors. In an effort to understand the state of satellite product fidelity, the Naval Research Laboratory and a newly reformed Global Energy and Water Cycle Experiment (GEWEX) aerosol panel have both initiated assessments of the nature of aerosol remote sensing uncertainty and bias. In this talk we go over areas of specific concern based on the authors’ experiences with the data, emphasizing the multi-sensor problem. We first enumerate potential biases, including retrieval, sampling/contextual, and cognitive bias. We show examples of how these biases can subsequently lead to the pitfalls of correlated/compensating errors, tautology, and confounding. The nature of bias is closely related to the information content of the sensor signal and its subsequent application to the derived aerosol quantity of interest (e.g., optical depth, flux, index of refraction, etc.). Consequently, purpose-specific validation methods must be employed, especially when generating multi-sensor products. Indeed, cloud and lower boundary condition biases in particular complicate the more typical methods of regressional bias elimination and histogram matching. We close with a discussion of sequestration of uncertainty in multi-sensor applications of

A Phenomenological Case Study: Teacher Bias Effects on Early Education Assessments

ERIC Educational Resources Information Center

Reynolds, Rebecca Jeannine

2012-01-01

This qualitative phenomenological case study explored the lived experiences of a purposive sample of 20 current and past early education teachers who have experience in assessing children through observational assessment. The purpose of this study was to determine if bias affects the documentation of observational assessment and the implementation…

A Mixed Phase Tale: New Ways of using in-situ cloud observations to reduce climate model biases in Southern Ocean

NASA Astrophysics Data System (ADS)

Gettelman, A.; Stith, J. L.

2014-12-01

Southern ocean clouds are a critical part of the earth's energy budget, and significant biases in the climatology of these clouds exist in models used to predict climate change. We compare in situ measurements of cloud microphysical properties of ice and liquid over the S. Ocean with constrained output from the atmospheric component of an Earth System Model. Observations taken during the HIAPER (the NSF/NCAR G-V aircraft) Pole-to-Pole Observations (HIPPO) multi-year field campaign are compared with simulations from the atmospheric component of the Community Earth System Model (CESM). Remarkably, CESM is able to accurately simulate the locations of cloud formation, and even cloud microphysical properties are comparable between the model and observations. Significantly, the simulations do not predict sufficient supercooled liquid. Altering the model cloud and aerosol processes to better reproduce the observations of supercooled liquid acts to reduce long-standing biases in S. Ocean clouds in CESM, which are typical of other models. Furthermore, sensitivity tests show where better observational constraints on aerosols and cloud microphysics can reduce uncertainty and biases in global models. These results are intended to show how we can connect large scale simulations with field observations in the S. Ocean to better understand Southern Ocean cloud processes and reduce biases in global climate simulations.

Validation of a weather forecast model at radiance level against satellite observations allowing quantification of temperature, humidity, and cloud-related biases

NASA Astrophysics Data System (ADS)

Bani Shahabadi, Maziar; Huang, Yi; Garand, Louis; Heilliette, Sylvain; Yang, Ping

2016-09-01

An established radiative transfer model (RTM) is adapted for simulating all-sky infrared radiance spectra from the Canadian Global Environmental Multiscale (GEM) model in order to validate its forecasts at the radiance level against Atmospheric InfraRed Sounder (AIRS) observations. Synthetic spectra are generated for 2 months from short-term (3-9 h) GEM forecasts. The RTM uses a monthly climatological land surface emissivity/reflectivity atlas. An updated ice particle optical property library was introduced for cloudy radiance calculations. Forward model brightness temperature (BT) biases are assessed to be of the order of ˜1 K for both clear-sky and overcast conditions. To quantify GEM forecast meteorological variables biases, spectral sensitivity kernels are generated and used to attribute radiance biases to surface and atmospheric temperatures, atmospheric humidity, and clouds biases. The kernel method, supplemented with retrieved profiles based on AIRS observations in collocation with a microwave sounder, achieves good closure in explaining clear-sky radiance biases, which are attributed mostly to surface temperature and upper tropospheric water vapor biases. Cloudy-sky radiance biases are dominated by cloud-induced radiance biases. Prominent GEM biases are identified as: (1) too low surface temperature over land, causing about -5 K bias in the atmospheric window region; (2) too high upper tropospheric water vapor, inducing about -3 K bias in the water vapor absorption band; (3) too few high clouds in the convective regions, generating about +10 K bias in window band and about +6 K bias in the water vapor band.

Risk of bias and confounding of observational studies of Zika virus infection: A scoping review of research protocols

PubMed Central

Haby, Michelle M.; Martínez-Vega, Ruth; Pinzón-Flores, Carlos E.; Smith, Emma; Pinart, Mariona; Broutet, Nathalie; Becerra-Posada, Francisco; Aldighieri, Sylvain; Van Kerkhove, Maria D.

2017-01-01

Introduction Given the severity and impact of the current Zika virus (ZIKV) outbreak in the Americas, numerous countries have rushed to develop research studies to assess ZIKV and its potential health consequences. In an effort to ensure that studies are comprehensive, both internally and externally valid, and with reliable results, the World Health Organization, the Pan American Health Organization, Institut Pasteur, the networks of Fiocruz, the Consortia for the Standardization of Influenza Seroepidemiology (CONSISE) and the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) have generated six standardized clinical and epidemiological research protocols and questionnaires to address key public health questions on ZIKV. Methods We conducted a systematic search of ongoing study protocols related to ZIKV research. We analyzed the content of protocols of 32 cohort studies and 13 case control studies for systematic bias that could produce erroneous results. Additionally we aimed to characterize the risks of bias and confounding in observational studies related to ZIKV and to propose ways to minimize them, including the use of six newly standardized research protocols. Results Observational studies of ZIKV face an array of challenges, including measurement of exposure and outcomes (microcephaly and Guillain-Barré Syndrome). Potential confounders need to be measured where known and controlled for in the analysis. Selection bias due to non-random selection is a significant issue, particularly in the case-control design, and losses to follow-up is equally important for the cohort design. Conclusion Observational research seeking to answer key questions on the ZIKV should consider these restrictions and take precautions to minimize bias in an effort to provide reliable and valid results. Utilization of the standardized research protocols developed by the WHO, PAHO, Institut Pasteur, and CONSISE will harmonize the key methodological aspects

Risk of bias and confounding of observational studies of Zika virus infection: A scoping review of research protocols.

PubMed

Reveiz, Ludovic; Haby, Michelle M; Martínez-Vega, Ruth; Pinzón-Flores, Carlos E; Elias, Vanessa; Smith, Emma; Pinart, Mariona; Broutet, Nathalie; Becerra-Posada, Francisco; Aldighieri, Sylvain; Van Kerkhove, Maria D

2017-01-01

Given the severity and impact of the current Zika virus (ZIKV) outbreak in the Americas, numerous countries have rushed to develop research studies to assess ZIKV and its potential health consequences. In an effort to ensure that studies are comprehensive, both internally and externally valid, and with reliable results, the World Health Organization, the Pan American Health Organization, Institut Pasteur, the networks of Fiocruz, the Consortia for the Standardization of Influenza Seroepidemiology (CONSISE) and the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) have generated six standardized clinical and epidemiological research protocols and questionnaires to address key public health questions on ZIKV. We conducted a systematic search of ongoing study protocols related to ZIKV research. We analyzed the content of protocols of 32 cohort studies and 13 case control studies for systematic bias that could produce erroneous results. Additionally we aimed to characterize the risks of bias and confounding in observational studies related to ZIKV and to propose ways to minimize them, including the use of six newly standardized research protocols. Observational studies of ZIKV face an array of challenges, including measurement of exposure and outcomes (microcephaly and Guillain-Barré Syndrome). Potential confounders need to be measured where known and controlled for in the analysis. Selection bias due to non-random selection is a significant issue, particularly in the case-control design, and losses to follow-up is equally important for the cohort design. Observational research seeking to answer key questions on the ZIKV should consider these restrictions and take precautions to minimize bias in an effort to provide reliable and valid results. Utilization of the standardized research protocols developed by the WHO, PAHO, Institut Pasteur, and CONSISE will harmonize the key methodological aspects of each study design to minimize bias at

Biases in the production and reception of collective knowledge: the case of hindsight bias in Wikipedia.

PubMed

Oeberst, Aileen; von der Beck, Ina; D Back, Mitja; Cress, Ulrike; Nestler, Steffen

2017-04-17

The Web 2.0 enabled collaboration at an unprecedented level. In one of the flagships of mass collaboration-Wikipedia-a large number of authors socially negotiate the world's largest compendium of knowledge. Several guidelines in Wikipedia restrict contributions to verifiable information from reliable sources to ensure recognized knowledge. Much psychological research demonstrates, however, that individual information processing is biased. This poses the question whether individual biases translate to Wikipedia articles or whether they are prevented by its guidelines. The present research makes use of hindsight bias to examine this question. To this end, we analyzed foresight and hindsight versions of Wikipedia articles regarding a broad variety of events (Study 1). We found the majority of articles not to contain traces of hindsight bias-contrary to prior individual research. However, for a particular category of events-disasters-we found robust evidence for hindsight bias. In a lab experiment (Study 2), we then examined whether individuals' hindsight bias is translated into articles under controlled conditions and tested whether collaborative writing-as present in Wikipedia-affects the resultant bias (vs. individual writing). Finally, we investigated the impact of biased Wikipedia articles on readers (Study 3). As predicted, biased articles elicited a hindsight bias in readers, who had not known of the event previously. Moreover, biased articles also affected individuals who knew about the event already, and who had already developed a hindsight bias: biased articles further increased their hindsight.

Specifying a target trial prevents immortal time bias and other self-inflicted injuries in observational analyses

PubMed Central

Hernán, Miguel A.; Sauer, Brian C.; Hernández-Díaz, Sonia; Platt, Robert; Shrier, Ian

2016-01-01

Many analyses of observational data are attempts to emulate a target trial. The emulation of the target trial may fail when researchers deviate from simple principles that guide the design and analysis of randomized experiments. We review a framework to describe and prevent biases, including immortal time bias, that result from a failure to align start of follow-up, specification of eligibility, and treatment assignment. We review some analytic approaches to avoid these problems in comparative effectiveness or safety research. PMID:27237061

The moderating role of cognitive biases on the relationship between negative affective states and psychotic-like experiences in non-clinical adults.

PubMed

Prochwicz, Katarzyna; Kłosowska, Joanna

2018-04-13

Negative emotions and cognitive biases are important factors underlying psychotic symptoms and psychotic-like experiences (PLEs); however, it is not clear whether these factors interact when they influence psychotic phenomena. The aim of our study was to investigate whether psychosis-related cognitive biases moderate the relationship between negative affective states, i.e. anxiety and depression, and psychotic-like experiences. The study sample contains 251 participants who have never been diagnosed with psychiatric disorders. Anxiety, depression, cognitive biases, and psychotic-like experiences were assessed with self-report questionnaires. A moderation analysis was performed to examine the relationship between the study variables. The analyses revealed that the link between anxiety and positive PLEs is moderated by External Attribution bias, whereas the relationship between depression and positive PLEs is moderated by Attention to Threat bias. Attributional bias was also found to moderate the association between depression and negative subclinical symptoms; Jumping to Conclusions bias served as a moderator in the link between anxiety and depression and negative PLEs. Further studies in clinical samples are required to verify the moderating role of individual cognitive biases on the relationship between negative emotional states and full-blown psychotic symptoms. Copyright © 2018 Elsevier B.V. All rights reserved.

Impact bias or underestimation? Outcome specifications predict the direction of affective forecasting errors.

PubMed

Buechel, Eva C; Zhang, Jiao; Morewedge, Carey K

2017-05-01

Affective forecasts are used to anticipate the hedonic impact of future events and decide which events to pursue or avoid. We propose that because affective forecasters are more sensitive to outcome specifications of events than experiencers, the outcome specification values of an event, such as its duration, magnitude, probability, and psychological distance, can be used to predict the direction of affective forecasting errors: whether affective forecasters will overestimate or underestimate its hedonic impact. When specifications are positively correlated with the hedonic impact of an event, forecasters will overestimate the extent to which high specification values will intensify and low specification values will discount its impact. When outcome specifications are negatively correlated with its hedonic impact, forecasters will overestimate the extent to which low specification values will intensify and high specification values will discount its impact. These affective forecasting errors compound additively when multiple specifications are aligned in their impact: In Experiment 1, affective forecasters underestimated the hedonic impact of winning a smaller prize that they expected to win, and they overestimated the hedonic impact of winning a larger prize that they did not expect to win. In Experiment 2, affective forecasters underestimated the hedonic impact of a short unpleasant video about a temporally distant event, and they overestimated the hedonic impact of a long unpleasant video about a temporally near event. Experiments 3A and 3B showed that differences in the affect-richness of forecasted and experienced events underlie these differences in sensitivity to outcome specifications, therefore accounting for both the impact bias and its reversal. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Chemosensory Communication of Gender Information: Masculinity Bias in Body Odor Perception and Femininity Bias Introduced by Chemosignals During Social Perception.

PubMed

Mutic, Smiljana; Moellers, Eileen M; Wiesmann, Martin; Freiherr, Jessica

2015-01-01

Human body odor is a source of important social information. In this study, we explore whether the sex of an individual can be established based on smelling axillary odor and whether exposure to male and female odors biases chemosensory and social perception. In a double-blind, pseudo-randomized application, 31 healthy normosmic heterosexual male and female raters were exposed to male and female chemosignals (odor samples of 27 heterosexual donors collected during a cardio workout) and a no odor sample. Recipients rated chemosensory samples on a masculinity-femininity scale and provided intensity, familiarity and pleasantness ratings. Additionally, the modulation of social perception (gender-neutral faces and personality attributes) and affective introspection (mood) by male and female chemosignals was assessed. Male and female axillary odors were rated as rather masculine, regardless of the sex of the donor. As opposed to the masculinity bias in the odor perception, a femininity bias modulating social perception appeared. A facilitated femininity detection in gender-neutral faces and personality attributes in male and female chemosignals appeared. No chemosensory effect on mood of the rater was observed. The results are discussed with regards to the use of male and female chemosignals in affective and social communication.

Perceiving emotions in neutral faces: expression processing is biased by affective person knowledge.

PubMed

Suess, Franziska; Rabovsky, Milena; Abdel Rahman, Rasha

2015-04-01

According to a widely held view, basic emotions such as happiness or anger are reflected in facial expressions that are invariant and uniquely defined by specific facial muscle movements. Accordingly, expression perception should not be vulnerable to influences outside the face. Here, we test this assumption by manipulating the emotional valence of biographical knowledge associated with individual persons. Faces of well-known and initially unfamiliar persons displaying neutral expressions were associated with socially relevant negative, positive or comparatively neutral biographical information. The expressions of faces associated with negative information were classified as more negative than faces associated with neutral information. Event-related brain potential modulations in the early posterior negativity, a component taken to reflect early sensory processing of affective stimuli such as emotional facial expressions, suggest that negative affective knowledge can bias the perception of faces with neutral expressions toward subjectively displaying negative emotions. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Evaluation of the Relative Contribution of Observing Systems in Reanalyses: Aircraft Temperature Bias and Analysis Innovations

NASA Technical Reports Server (NTRS)

Bosilovich, Michael G.; Dasilva, Arindo M.

2012-01-01

Reanalyses have become important sources of data in weather and climate research. While observations are the most crucial component of the systems, few research projects consider carefully the multitudes of assimilated observations and their impact on the results. This is partly due to the diversity of observations and their individual complexity, but also due to the unfriendly nature of the data formats. Here, we discuss the NASA Modern-Era Retrospective analysis for Research and Applications (MERRA) and a companion dataset, the Gridded Innovations and Observations (GIO). GIO is simply a post-processing of the assimilated observations and their innovations (forecast error and analysis error) to a common spatio-temporal grid, following that of the MERRA analysis fields. This data includes in situ, retrieved and radiance observations that are assimilated and used in the reanalysis. While all these disparate observations and statistics are in a uniform easily accessible format, there are some limitations. Similar observations are binned to the grid, so that multiple observations are combined in the gridding process. The data is then implicitly thinned. Some details in the meta data may also be lost (e.g. aircraft or station ID). Nonetheless, the gridded observations should provide easy access to all the observations input to the reanalysis. To provide an example of the GIO data, a case study evaluating observing systems over the United States and statistics is presented, and demonstrates the evaluation of the observations and the data assimilation. The GIO data is used to collocate 200mb Radiosonde and Aircraft temperature measurements from 1979-2009. A known warm bias of the aircraft measurements is apparent compared to the radiosonde data. However, when larger quantities of aircraft data are available, they dominate the analysis and the radiosonde data become biased against the forecast. When AMSU radiances become available the radiosonde and aircraft analysis and

Meta-assessment of bias in science

PubMed Central

Fanelli, Daniele; Costas, Rodrigo; Ioannidis, John P. A.

2017-01-01

Numerous biases are believed to affect the scientific literature, but their actual prevalence across disciplines is unknown. To gain a comprehensive picture of the potential imprint of bias in science, we probed for the most commonly postulated bias-related patterns and risk factors, in a large random sample of meta-analyses taken from all disciplines. The magnitude of these biases varied widely across fields and was overall relatively small. However, we consistently observed a significant risk of small, early, and highly cited studies to overestimate effects and of studies not published in peer-reviewed journals to underestimate them. We also found at least partial confirmation of previous evidence suggesting that US studies and early studies might report more extreme effects, although these effects were smaller and more heterogeneously distributed across meta-analyses and disciplines. Authors publishing at high rates and receiving many citations were, overall, not at greater risk of bias. However, effect sizes were likely to be overestimated by early-career researchers, those working in small or long-distance collaborations, and those responsible for scientific misconduct, supporting hypotheses that connect bias to situational factors, lack of mutual control, and individual integrity. Some of these patterns and risk factors might have modestly increased in intensity over time, particularly in the social sciences. Our findings suggest that, besides one being routinely cautious that published small, highly-cited, and earlier studies may yield inflated results, the feasibility and costs of interventions to attenuate biases in the literature might need to be discussed on a discipline-specific and topic-specific basis. PMID:28320937

Cosmic shear bias and calibration in dark energy studies

NASA Astrophysics Data System (ADS)

Taylor, A. N.; Kitching, T. D.

2018-07-01

With the advent of large-scale weak lensing surveys there is a need to understand how realistic, scale-dependent systematics bias cosmic shear and dark energy measurements, and how they can be removed. Here, we show how spatially varying image distortions are convolved with the shear field, mixing convergence E and B modes, and bias the observed shear power spectrum. In practise, many of these biases can be removed by calibration to data or simulations. The uncertainty in this calibration is marginalized over, and we calculate how this propagates into parameter estimation and degrades the dark energy Figure-of-Merit. We find that noise-like biases affect dark energy measurements the most, while spikes in the bias power have the least impact. We argue that, in order to remove systematic biases in cosmic shear surveys and maintain statistical power, effort should be put into improving the accuracy of the bias calibration rather than minimizing the size of the bias. In general, this appears to be a weaker condition for bias removal. We also investigate how to minimize the size of the calibration set for a fixed reduction in the Figure-of-Merit. Our results can be used to correctly model the effect of biases and calibration on a cosmic shear survey, assess their impact on the measurement of modified gravity and dark energy models, and to optimize survey and calibration requirements.

Specifying a target trial prevents immortal time bias and other self-inflicted injuries in observational analyses.

PubMed

Hernán, Miguel A; Sauer, Brian C; Hernández-Díaz, Sonia; Platt, Robert; Shrier, Ian

2016-11-01

Many analyses of observational data are attempts to emulate a target trial. The emulation of the target trial may fail when researchers deviate from simple principles that guide the design and analysis of randomized experiments. We review a framework to describe and prevent biases, including immortal time bias, that result from a failure to align start of follow-up, specification of eligibility, and treatment assignment. We review some analytic approaches to avoid these problems in comparative effectiveness or safety research. Copyright © 2016 Elsevier Inc. All rights reserved.

How does the cosmic large-scale structure bias the Hubble diagram?

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

Fleury, Pierre; Clarkson, Chris; Maartens, Roy, E-mail: pierre.fleury@uct.ac.za, E-mail: chris.clarkson@qmul.ac.uk, E-mail: roy.maartens@gmail.com

2017-03-01

The Hubble diagram is one of the cornerstones of observational cosmology. It is usually analysed assuming that, on average, the underlying relation between magnitude and redshift matches the prediction of a Friedmann-Lemaître-Robertson-Walker model. However, the inhomogeneity of the Universe generically biases these observables, mainly due to peculiar velocities and gravitational lensing, in a way that depends on the notion of average used in theoretical calculations. In this article, we carefully derive the notion of average which corresponds to the observation of the Hubble diagram. We then calculate its bias at second-order in cosmological perturbations, and estimate the consequences on themore » inference of cosmological parameters, for various current and future surveys. We find that this bias deeply affects direct estimations of the evolution of the dark-energy equation of state. However, errors in the standard inference of cosmological parameters remain smaller than observational uncertainties, even though they reach percent level on some parameters; they reduce to sub-percent level if an optimal distance indicator is used.« less

Evaluation of Bias Correction Method for Satellite-Based Rainfall Data

PubMed Central

Bhatti, Haris Akram; Rientjes, Tom; Haile, Alemseged Tamiru; Habib, Emad; Verhoef, Wouter

2016-01-01

With the advances in remote sensing technology, satellite-based rainfall estimates are gaining attraction in the field of hydrology, particularly in rainfall-runoff modeling. Since estimates are affected by errors correction is required. In this study, we tested the high resolution National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Centre (CPC) morphing technique (CMORPH) satellite rainfall product (CMORPH) in the Gilgel Abbey catchment, Ethiopia. CMORPH data at 8 km-30 min resolution is aggregated to daily to match in-situ observations for the period 2003–2010. Study objectives are to assess bias of the satellite estimates, to identify optimum window size for application of bias correction and to test effectiveness of bias correction. Bias correction factors are calculated for moving window (MW) sizes and for sequential windows (SW’s) of 3, 5, 7, 9, …, 31 days with the aim to assess error distribution between the in-situ observations and CMORPH estimates. We tested forward, central and backward window (FW, CW and BW) schemes to assess the effect of time integration on accumulated rainfall. Accuracy of cumulative rainfall depth is assessed by Root Mean Squared Error (RMSE). To systematically correct all CMORPH estimates, station based bias factors are spatially interpolated to yield a bias factor map. Reliability of interpolation is assessed by cross validation. The uncorrected CMORPH rainfall images are multiplied by the interpolated bias map to result in bias corrected CMORPH estimates. Findings are evaluated by RMSE, correlation coefficient (r) and standard deviation (SD). Results showed existence of bias in the CMORPH rainfall. It is found that the 7 days SW approach performs best for bias correction of CMORPH rainfall. The outcome of this study showed the efficiency of our bias correction approach. PMID:27314363

Evaluation of Bias Correction Method for Satellite-Based Rainfall Data.

PubMed

Bhatti, Haris Akram; Rientjes, Tom; Haile, Alemseged Tamiru; Habib, Emad; Verhoef, Wouter

2016-06-15

With the advances in remote sensing technology, satellite-based rainfall estimates are gaining attraction in the field of hydrology, particularly in rainfall-runoff modeling. Since estimates are affected by errors correction is required. In this study, we tested the high resolution National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Centre (CPC) morphing technique (CMORPH) satellite rainfall product (CMORPH) in the Gilgel Abbey catchment, Ethiopia. CMORPH data at 8 km-30 min resolution is aggregated to daily to match in-situ observations for the period 2003-2010. Study objectives are to assess bias of the satellite estimates, to identify optimum window size for application of bias correction and to test effectiveness of bias correction. Bias correction factors are calculated for moving window (MW) sizes and for sequential windows (SW's) of 3, 5, 7, 9, …, 31 days with the aim to assess error distribution between the in-situ observations and CMORPH estimates. We tested forward, central and backward window (FW, CW and BW) schemes to assess the effect of time integration on accumulated rainfall. Accuracy of cumulative rainfall depth is assessed by Root Mean Squared Error (RMSE). To systematically correct all CMORPH estimates, station based bias factors are spatially interpolated to yield a bias factor map. Reliability of interpolation is assessed by cross validation. The uncorrected CMORPH rainfall images are multiplied by the interpolated bias map to result in bias corrected CMORPH estimates. Findings are evaluated by RMSE, correlation coefficient (r) and standard deviation (SD). Results showed existence of bias in the CMORPH rainfall. It is found that the 7 days SW approach performs best for bias correction of CMORPH rainfall. The outcome of this study showed the efficiency of our bias correction approach.

Observational drawing biases are predicted by biases in perception: Empirical support of the misperception hypothesis of drawing accuracy with respect to two angle illusions.

PubMed

Ostrofsky, Justin; Kozbelt, Aaron; Cohen, Dale J

2015-01-01

We tested the misperception hypothesis of drawing errors, which states that drawing accuracy is strongly influenced by the perceptual encoding of a to-be-drawn stimulus. We used a highly controlled experimental paradigm in which nonartist participants made perceptual judgements and drawings of angles under identical stimulus exposure conditions. Experiment 1 examined the isosceles/scalene triangle angle illusion; congruent patterns of bias in the perception and drawing tasks were found for 40 and 60° angles, but not for 20 or 80° angles, providing mixed support for the misperception hypothesis. Experiment 2 examined shape constancy effects with respect to reproductions of single acute or obtuse angles; congruent patterns of bias in the perception and drawing tasks were found across a range of angles from 29 to 151°, providing strong support for the misperception hypothesis. In both experiments, perceptual and drawing biases were positively correlated. These results are largely consistent with the misperception hypothesis, suggesting that inaccurate perceptual encoding of angles is an important reason that nonartists err in drawing angles from observation.

The impact of selection bias on vaccine effectiveness estimates from test-negative studies.

PubMed

Jackson, Michael L; Phillips, C Hallie; Benoit, Joyce; Kiniry, Erika; Madziwa, Lawrence; Nelson, Jennifer C; Jackson, Lisa A

2018-01-29

Estimates of vaccine effectiveness (VE) from test-negative studies may be subject to selection bias. In the context of influenza VE, we used simulations to identify situations in which meaningful selection bias can occur. We also analyzed observational study data for evidence of selection bias. For the simulation study, we defined a hypothetical population whose members are at risk for acute respiratory illness (ARI) due to influenza and other pathogens. An unmeasured "healthcare seeking proclivity" affects both probability of vaccination and probability of seeking care for an ARI. We varied the direction and magnitude of these effects and identified situations where meaningful bias occurred. For the observational study, we reanalyzed data from the United States Influenza VE Network, an ongoing test-negative study. We compared "bias-naïve" VE estimates to bias-adjusted estimates, which used data from the source populations to correct for sampling bias. In the simulation study, an unmeasured care-seeking proclivity could create selection bias if persons with influenza ARI were more (or less) likely to seek care than persons with non-influenza ARI. However, selection bias was only meaningful when rates of care seeking between influenza ARI and non-influenza ARI were very different. In the observational study, the bias-naïve VE estimate of 55% (95% CI, 47--62%) was trivially different from the bias-adjusted VE estimate of 57% (95% CI, 49--63%). In combination, these studies suggest that while selection bias is possible in test-negative VE studies, this bias in unlikely to be meaningful under conditions likely to be encountered in practice. Researchers and public health officials can continue to rely on VE estimates from test-negative studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

"The impact of uncertain threat on affective bias: Individual differences in response to ambiguity": Correction.

PubMed

2018-04-01

Reports an error in "The impact of uncertain threat on affective bias: Individual differences in response to ambiguity" by Maital Neta, Julie Cantelon, Zachary Haga, Caroline R. Mahoney, Holly A. Taylor and F. Caroline Davis ( Emotion , 2017[Dec], Vol 17[8], 1137-1143). In this article, the copyright attribution was incorrectly listed under the Creative Commons CC-BY license due to production-related error. The correct copyright should be "In the public domain." The online version of this article has been corrected. (The following abstract of the original article appeared in record 2017-40275-001.) Individuals who operate under highly stressful conditions (e.g., military personnel and first responders) are often faced with the challenge of quickly interpreting ambiguous information in uncertain and threatening environments. When faced with ambiguity, it is likely adaptive to view potentially dangerous stimuli as threatening until contextual information proves otherwise. One laboratory-based paradigm that can be used to simulate uncertain threat is known as threat of shock (TOS), in which participants are told that they might receive mild but unpredictable electric shocks while performing an unrelated task. The uncertainty associated with this potential threat induces a state of emotional arousal that is not overwhelmingly stressful, but has widespread-both adaptive and maladaptive-effects on cognitive and affective function. For example, TOS is thought to enhance aversive processing and abolish positivity bias. Importantly, in certain situations (e.g., when walking home alone at night), this anxiety can promote an adaptive state of heightened vigilance and defense mobilization. In the present study, we used TOS to examine the effects of uncertain threat on valence bias, or the tendency to interpret ambiguous social cues as positive or negative. As predicted, we found that heightened emotional arousal elicited by TOS was associated with an increased tendency to

"In the Eye of the Beholder": Sex Bias in Observations and Ratings of Children's Aggression

ERIC Educational Resources Information Center

Pellegrini, Anthony D.

2011-01-01

The processes by which children are classified as aggressive have important educational and research implications. For example, aggression in childhood reliably predicts dropping out of school and incarceration. The author argues that the sex-role stereotypicality of aggression produces bias in both observers and raters of student behavior. The…

Sleep-related attentional bias in poor versus good sleepers is independent of affective valence.

PubMed

Barclay, Nicola L; Ellis, Jason G

2013-08-01

Contradictory evidence exists relating to the presence of an attention bias to sleep-related stimuli in poor sleepers/insomnia using the emotional Stroop task (EST). These inconsistencies may be due to methodological issues related to the affective valence of the sleep-related stimuli. Thus, individuals may attend differentially to sleep-related stimuli not because of their 'sleep' properties, but their negativity. The current study addresses this by controlling the affective valence of sleep-related words. A total of 107 participants [mean age = 33.22 years, standard deviation (SD) = 12.31 years; 61.7% female] were recruited during an evening event at the Newcastle Science Festival. Participants completed the Pittsburgh Sleep Quality Index (PSQI) and a computerized EST containing 20 non-affective sleep-related, 20 neutral and 20 negatively valenced threat words. Good and poor sleepers were categorized using the PSQI. There were no significant differences between groups on response latency to sleep-related words (t(105) = -0.30, P = 0.76). However, the interaction between good versus poor sleepers and word-type on response latency was significant (F(2,210) = 3.06, P < 0.05). Poor sleepers took longer to respond to sleep-related words (mean = 723.35, SD = 172.55) compared to threat words (mean = 694.63, SD = 162.17) than good sleepers (mean = 713.20, SD = 166.32; and mean = 716.65, SD = 181.14). The results demonstrate the presence of an attention bias towards sleep-related stimuli compared to threat stimuli in poor sleepers. Accordingly, poor sleepers may be consumed by stimuli relevant to their specific difficulties, as well as being more highly attuned to negative cues that signal anxious states. Thus, the present research suggests that there are two opposing forces at play: one which facilitates performance (non-specific threats) and one which hinders performance (personally relevant threats). © 2013 European Sleep Research Society.

Chemosensory Communication of Gender Information: Masculinity Bias in Body Odor Perception and Femininity Bias Introduced by Chemosignals During Social Perception

PubMed Central

Mutic, Smiljana; Moellers, Eileen M.; Wiesmann, Martin; Freiherr, Jessica

2016-01-01

Human body odor is a source of important social information. In this study, we explore whether the sex of an individual can be established based on smelling axillary odor and whether exposure to male and female odors biases chemosensory and social perception. In a double-blind, pseudo-randomized application, 31 healthy normosmic heterosexual male and female raters were exposed to male and female chemosignals (odor samples of 27 heterosexual donors collected during a cardio workout) and a no odor sample. Recipients rated chemosensory samples on a masculinity-femininity scale and provided intensity, familiarity and pleasantness ratings. Additionally, the modulation of social perception (gender-neutral faces and personality attributes) and affective introspection (mood) by male and female chemosignals was assessed. Male and female axillary odors were rated as rather masculine, regardless of the sex of the donor. As opposed to the masculinity bias in the odor perception, a femininity bias modulating social perception appeared. A facilitated femininity detection in gender-neutral faces and personality attributes in male and female chemosignals appeared. No chemosensory effect on mood of the rater was observed. The results are discussed with regards to the use of male and female chemosignals in affective and social communication. PMID:26834656

Human observers are biased in judging the angular approach of a projectile.

PubMed

Welchman, Andrew E; Tuck, Val L; Harris, Julie M

2004-01-01

How do we decide whether an object approaching us will hit us? The optic array provides information sufficient for us to determine the approaching trajectory of a projectile. However, when using binocular information, observers report that trajectories near the mid-sagittal plane are wider than they actually are. Here we extend this work to consider stimuli containing additional depth cues. We measure observers' estimates of trajectory direction first for computer rendered, stereoscopically presented, rich-cue objects, and then for real objects moving in the world. We find that, under both rich cue conditions and with real moving objects, observers show positive bias, overestimating the angle of approach when movement is near the mid-sagittal plane. The findings question whether the visual system, using both binocular and monocular cues to depth, can make explicit estimates of the 3-D location and movement of objects in depth.

Self-face Captures, Holds, and Biases Attention.

PubMed

Wójcik, Michał J; Nowicka, Maria M; Kotlewska, Ilona; Nowicka, Anna

2017-01-01

The implicit self-recognition process may take place already in the pre-attentive stages of perception. After a silent stimulus has captured attention, it is passed on to the attentive stage where it can affect decision making and responding. Numerous studies show that the presence of self-referential information affects almost every cognitive level. These effects may share a common and fundamental basis in an attentional mechanism, conceptualized as attentional bias: the exaggerated deployment of attentional resources to a salient stimulus. A gold standard in attentional bias research is the dot-probe paradigm. In this task, a prominent stimulus (cue) and a neutral stimulus are presented in different spatial locations, followed by the presentation of a target. In the current study we aimed at investigating whether the self-face captures, holds and biases attention when presented as a task-irrelevant stimulus. In two dot-probe experiments coupled with the event-related potential (ERP) technique we analyzed the following relevant ERPs components: N2pc and SPCN which reflect attentional shifts and the maintenance of attention, respectively. An inter-stimulus interval separating face-cues and probes (800 ms) was introduced only in the first experiment. In line with our predictions, in Experiment 1 the self-face elicited the N2pc and the SPCN component. In Experiment 2 in addition to N2pc, an attentional bias was observed. Our results indicate that unintentional self-face processing disables the top-down control setting to filter out distractors, thus leading to the engagement of attentional resources and visual short-term memory.

FIP BIAS EVOLUTION IN A DECAYING ACTIVE REGION

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

Baker, D.; Yardley, S. L.; Driel-Gesztelyi, L. van

Solar coronal plasma composition is typically characterized by first ionization potential (FIP) bias. Using spectra obtained by Hinode’s EUV Imaging Spectrometer instrument, we present a series of large-scale, spatially resolved composition maps of active region (AR)11389. The composition maps show how FIP bias evolves within the decaying AR during the period 2012 January 4–6. Globally, FIP bias decreases throughout the AR. We analyzed areas of significant plasma composition changes within the decaying AR and found that small-scale evolution in the photospheric magnetic field is closely linked to the FIP bias evolution observed in the corona. During the AR’s decay phase,more » small bipoles emerging within supergranular cells reconnect with the pre-existing AR field, creating a pathway along which photospheric and coronal plasmas can mix. The mixing timescales are shorter than those of plasma enrichment processes. Eruptive activity also results in shifting the FIP bias closer to photospheric in the affected areas. Finally, the FIP bias still remains dominantly coronal only in a part of the AR’s high-flux density core. We conclude that in the decay phase of an AR’s lifetime, the FIP bias is becoming increasingly modulated by episodes of small-scale flux emergence, i.e., decreasing the AR’s overall FIP bias. Our results show that magnetic field evolution plays an important role in compositional changes during AR development, revealing a more complex relationship than expected from previous well-known Skylab results showing that FIP bias increases almost linearly with age in young ARs.« less

Reliving emotional personal memories: affective biases linked to personality and sex-related differences.

PubMed

Denkova, Ekaterina; Dolcos, Sanda; Dolcos, Florin

2012-06-01

Although available evidence suggests that the emotional valence and recollective properties of autobiographical memories (AMs) may be influenced by personality- and sex-related differences, overall these relationships remain poorly understood. The present study investigated these issues by comparing the effect of general personality traits (extraversion and neuroticism) and specific traits linked to emotion regulation (ER) strategies (reappraisal and suppression) on the retrieval of emotional AMs and on the associated postretrieval emotional states, in men and women. First, extraversion predicted recollection of positive AMs in both men and women, whereas neuroticism predicted the proportion of negative AMs in men and the frequency of rehearsing negative AMs in women. Second, reappraisal predicted positive AMs in men, and suppression predicted negative AMs in women. Third, while reliving of positive memories had an overall indirect effect on postretrieval positive mood through extraversion, reliving of negative AMs had a direct effect on postretrieval negative mood, which was linked to inefficient engagement of suppression in women. Our findings suggest that personality traits associated with positive affect predict recollection of positive AMs and maintenance of a positive mood, whereas personality traits associated with negative affect, along with differential engagement of habitual ER strategies in men and women, predict sex-related differences in the recollection and experiencing of negative AMs. These findings provide insight into the factors that influence affective biases in reliving AMs, and into their possible link to sex-related differences in the susceptibility to affective disorders.

Prefrontal cortex stimulation does not affect emotional bias, but may slow emotion identification.

PubMed

Nord, Camilla L; Forster, Sophie; Halahakoon, D Chamith; Penton-Voak, Ian S; Munafò, Marcus R; Roiser, Jonathan P

2017-05-01

Transcranial direct current stimulation (tDCS) has recently garnered attention as a putative depression treatment. However, the cognitive mechanisms by which it exerts an antidepressant effect are unclear: tDCS may directly alter 'hot' emotional processing biases, or alleviate depression through changes in 'cold' (non-emotional) cognitive function. Here, 75 healthy participants performed a facial emotion identification task during 20 minutes of anodal or sham tDCS over the left dorsolateral prefrontal cortex (DLPFC) in a double-blind, within-subject crossover design. A subset of 31 participants additionally completed a task measuring attentional distraction during stimulation. Compared to sham stimulation, anodal tDCS of the left DLPFC resulted in an increase in response latency across all emotional conditions. Bayesian analysis showed definitively that tDCS exerted no emotion-dependent effect on behaviour. Thus, we demonstrate that anodal tDCS produces a general, rather than an emotion-specific, effect. We also report a preliminary finding in the subset of participants who completed the distractibility task: increased distractibility during active stimulation correlated significantly with the degree to which tDCS slowed emotion identification. Our results provide insight into the possible mechanisms by which DLPFC tDCS may treat symptoms of depression, suggesting that it may not alter emotional biases, but instead may affect 'cold' cognitive processes. © The Author (2017). Published by Oxford University Press.

A modified carrier-to-code leveling method for retrieving ionospheric observables and detecting short-term temporal variability of receiver differential code biases

NASA Astrophysics Data System (ADS)

Zhang, Baocheng; Teunissen, Peter J. G.; Yuan, Yunbin; Zhang, Xiao; Li, Min

2018-03-01

Sensing the ionosphere with the global positioning system involves two sequential tasks, namely the ionospheric observable retrieval and the ionospheric parameter estimation. A prominent source of error has long been identified as short-term variability in receiver differential code bias (rDCB). We modify the carrier-to-code leveling (CCL), a method commonly used to accomplish the first task, through assuming rDCB to be unlinked in time. Aside from the ionospheric observables, which are affected by, among others, the rDCB at one reference epoch, the Modified CCL (MCCL) can also provide the rDCB offsets with respect to the reference epoch as by-products. Two consequences arise. First, MCCL is capable of excluding the effects of time-varying rDCB from the ionospheric observables, which, in turn, improves the quality of ionospheric parameters of interest. Second, MCCL has significant potential as a means to detect between-epoch fluctuations experienced by rDCB of a single receiver.

Eye Movements while Reading Biased Homographs: Effects of Prior Encounter and Biasing Context on Reducing the Subordinate Bias Effect

PubMed Central

Leinenger, Mallorie; Rayner, Keith

2013-01-01

Readers experience processing difficulties when reading biased homographs preceded by subordinate-biasing contexts. Attempts to overcome this processing deficit have often failed to reduce the subordinate bias effect (SBE). In the present studies, we examined the processing of biased homographs preceded by single-sentence, subordinate-biasing contexts, and varied whether this preceding context contained a prior instance of the homograph or a control word/phrase. Having previously encountered the homograph earlier in the sentence reduced the SBE for the subsequent encounter, while simply instantiating the subordinate meaning produced processing difficulty. We compared these reductions in reading times to differences in processing time between dominant-biased repeated and non-repeated conditions in order to verify that the reductions observed in the subordinate cases did not simply reflect a general repetition benefit. Our results indicate that a strong, subordinate-biasing context can interact during lexical access to overcome the activation from meaning frequency and reduce the SBE during reading. PMID:24073328

Biased figure-ground assignment affects conscious object recognition in spatial neglect.

PubMed

Eramudugolla, Ranmalee; Driver, Jon; Mattingley, Jason B

2010-09-01

Unilateral spatial neglect is a disorder of attention and spatial representation, in which early visual processes such as figure-ground segmentation have been assumed to be largely intact. There is evidence, however, that the spatial attention bias underlying neglect can bias the segmentation of a figural region from its background. Relatively few studies have explicitly examined the effect of spatial neglect on processing the figures that result from such scene segmentation. Here, we show that a neglect patient's bias in figure-ground segmentation directly influences his conscious recognition of these figures. By varying the relative salience of figural and background regions in static, two-dimensional displays, we show that competition between elements in such displays can modulate a neglect patient's ability to recognise parsed figures in a scene. The findings provide insight into the interaction between scene segmentation, explicit object recognition, and attention.

A Diffusion Model Analysis of Decision Biases Affecting Delayed Recognition of Emotional Stimuli

PubMed Central

Bowen, Holly J.; Spaniol, Julia; Patel, Ronak; Voss, Andreas

2016-01-01

Previous empirical work suggests that emotion can influence accuracy and cognitive biases underlying recognition memory, depending on the experimental conditions. The current study examines the effects of arousal and valence on delayed recognition memory using the diffusion model, which allows the separation of two decision biases thought to underlie memory: response bias and memory bias. Memory bias has not been given much attention in the literature but can provide insight into the retrieval dynamics of emotion modulated memory. Participants viewed emotional pictorial stimuli; half were given a recognition test 1-day later and the other half 7-days later. Analyses revealed that emotional valence generally evokes liberal responding, whereas high arousal evokes liberal responding only at a short retention interval. The memory bias analyses indicated that participants experienced greater familiarity with high-arousal compared to low-arousal items and this pattern became more pronounced as study-test lag increased; positive items evoke greater familiarity compared to negative and this pattern remained stable across retention interval. The findings provide insight into the separate contributions of valence and arousal to the cognitive mechanisms underlying delayed emotion modulated memory. PMID:26784108

A Diffusion Model Analysis of Decision Biases Affecting Delayed Recognition of Emotional Stimuli.

PubMed

Bowen, Holly J; Spaniol, Julia; Patel, Ronak; Voss, Andreas

2016-01-01

Previous empirical work suggests that emotion can influence accuracy and cognitive biases underlying recognition memory, depending on the experimental conditions. The current study examines the effects of arousal and valence on delayed recognition memory using the diffusion model, which allows the separation of two decision biases thought to underlie memory: response bias and memory bias. Memory bias has not been given much attention in the literature but can provide insight into the retrieval dynamics of emotion modulated memory. Participants viewed emotional pictorial stimuli; half were given a recognition test 1-day later and the other half 7-days later. Analyses revealed that emotional valence generally evokes liberal responding, whereas high arousal evokes liberal responding only at a short retention interval. The memory bias analyses indicated that participants experienced greater familiarity with high-arousal compared to low-arousal items and this pattern became more pronounced as study-test lag increased; positive items evoke greater familiarity compared to negative and this pattern remained stable across retention interval. The findings provide insight into the separate contributions of valence and arousal to the cognitive mechanisms underlying delayed emotion modulated memory.

The grouping benefit in extinction: overcoming the temporal order bias.

PubMed

Rappaport, Sarah J; Riddoch, M Jane; Humphreys, Glyn W

2011-01-01

Grouping between contra- and ipsilesional stimuli can alleviate the lateralised bias in spatial extinction (Gilchrist, Humphreys, & Riddoch, 1996; Ward, Goodrich, & Driver, 1994). In the current study we demonstrate for the first time that perceptual grouping can also modulate the spatio/temporal biases in temporal order judgements affecting the temporal as well as the spatial coding of stimuli. Perceived temporal order was assessed by presenting two coloured letter stimuli in either hemi-field temporally segregated by a range of onset-intervals. Items were either identical (grouping condition) or differed in both shape and colour (non-grouping condition). Observers were required to indicate which item appeared second. Patients with visual extinction had a bias against the contralesional item appearing first, but this was modulated by perceptual grouping. When both items were identical in shape and colour the temporal bias against reporting the contralesional item was reduced. The results suggest that grouping can alter the coding of temporal relations between stimuli. Copyright © 2010 Elsevier Ltd. All rights reserved.

Variable Autosomal and X Divergence Near and Far from Genes Affects Estimates of Male Mutation Bias in Great Apes

PubMed Central

Narang, Pooja; Wilson Sayres, Melissa A.

2016-01-01

Male mutation bias, when more mutations are passed on via the male germline than via the female germline, is observed across mammals. One common way to infer the magnitude of male mutation bias, α, is to compare levels of neutral sequence divergence between genomic regions that spend different amounts of time in the male and female germline. For great apes, including human, we show that estimates of divergence are reduced in putatively unconstrained regions near genes relative to unconstrained regions far from genes. Divergence increases with increasing distance from genes on both the X chromosome and autosomes, but increases faster on the X chromosome than autosomes. As a result, ratios of X/A divergence increase with increasing distance from genes and corresponding estimates of male mutation bias are significantly higher in intergenic regions near genes versus far from genes. Future studies in other species will need to carefully consider the effect that genomic location will have on estimates of male mutation bias. PMID:27702816

Facial affect processing in social anxiety disorder with early onset: evidence of an intensity amplification bias.

PubMed

Schwab, Daniela; Schienle, Anne

2018-06-01

The present event-related potential (ERP) study investigated for the first time whether children with early-onset social anxiety disorder (SAD) process affective facial expressions of varying intensities differently than non-anxious controls. Participants were 15 SAD patients and 15 non-anxious controls (mean age of 9 years). They were presented with schematic faces displaying anger and happiness at four intensity levels (25%, 50%, 75%, and 100%), as well as with neutral faces. ERPs in early and later time windows (P100, N170, late positivity [LP]), as well as affective ratings (valence and arousal) for the faces, were recorded. SAD patients rated the faces as generally more arousing, regardless of the type of emotion and intensity. Moreover, they displayed enhanced right-parietal LP (350-650 ms). Both arousal ratings and LP reflect stimulus intensity. Therefore, this study provides first evidence of an intensity amplification bias in pediatric SAD during facial affect processing.

Reassessing biases and other uncertainties in sea surface temperature observations measured in situ since 1850: 2. Biases and homogenization

NASA Astrophysics Data System (ADS)

Kennedy, J. J.; Rayner, N. A.; Smith, R. O.; Parker, D. E.; Saunby, M.

2011-07-01

Changes in instrumentation and data availability have caused time-varying biases in estimates of global and regional average sea surface temperature. The size of the biases arising from these changes are estimated and their uncertainties evaluated. The estimated biases and their associated uncertainties are largest during the period immediately following the Second World War, reflecting the rapid and incompletely documented changes in shipping and data availability at the time. Adjustments have been applied to reduce these effects in gridded data sets of sea surface temperature and the results are presented as a set of interchangeable realizations. Uncertainties of estimated trends in global and regional average sea surface temperature due to bias adjustments since the Second World War are found to be larger than uncertainties arising from the choice of analysis technique, indicating that this is an important source of uncertainty in analyses of historical sea surface temperatures. Despite this, trends over the twentieth century remain qualitatively consistent.

Interpretation biases in paranoia.

PubMed

Savulich, George; Freeman, Daniel; Shergill, Sukhi; Yiend, Jenny

2015-01-01

Information in the environment is frequently ambiguous in meaning. Emotional ambiguity, such as the stare of a stranger, or the scream of a child, encompasses possible good or bad emotional consequences. Those with elevated vulnerability to affective disorders tend to interpret such material more negatively than those without, a phenomenon known as "negative interpretation bias." In this study we examined the relationship between vulnerability to psychosis, measured by trait paranoia, and interpretation bias. One set of material permitted broadly positive/negative (valenced) interpretations, while another allowed more or less paranoid interpretations, allowing us to also investigate the content specificity of interpretation biases associated with paranoia. Regression analyses (n=70) revealed that trait paranoia, trait anxiety, and cognitive inflexibility predicted paranoid interpretation bias, whereas trait anxiety and cognitive inflexibility predicted negative interpretation bias. In a group comparison those with high levels of trait paranoia were negatively biased in their interpretations of ambiguous information relative to those with low trait paranoia, and this effect was most pronounced for material directly related to paranoid concerns. Together these data suggest that a negative interpretation bias occurs in those with elevated vulnerability to paranoia, and that this bias may be strongest for material matching paranoid beliefs. We conclude that content-specific biases may be important in the cause and maintenance of paranoid symptoms. Copyright © 2014. Published by Elsevier Ltd.

Large-scale galaxy bias

NASA Astrophysics Data System (ADS)

Desjacques, Vincent; Jeong, Donghui; Schmidt, Fabian

2018-02-01

This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy statistics. We then review the excursion-set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

Understanding Unconscious Bias and Unintentional Racism

ERIC Educational Resources Information Center

Moule, Jean

2009-01-01

Unconscious biases affect one's relationships, whether they are fleeting relationships in airports or longer term relationships between teachers and students, teachers and parents, teachers and other educators. In this article, the author argues that understanding one's possible biases is essential for developing community in schools.…

Racial bias shapes social reinforcement learning.

PubMed

Lindström, Björn; Selbing, Ida; Molapour, Tanaz; Olsson, Andreas

2014-03-01

Both emotional facial expressions and markers of racial-group belonging are ubiquitous signals in social interaction, but little is known about how these signals together affect future behavior through learning. To address this issue, we investigated how emotional (threatening or friendly) in-group and out-group faces reinforced behavior in a reinforcement-learning task. We asked whether reinforcement learning would be modulated by intergroup attitudes (i.e., racial bias). The results showed that individual differences in racial bias critically modulated reinforcement learning. As predicted, racial bias was associated with more efficiently learned avoidance of threatening out-group individuals. We used computational modeling analysis to quantitatively delimit the underlying processes affected by social reinforcement. These analyses showed that racial bias modulates the rate at which exposure to threatening out-group individuals is transformed into future avoidance behavior. In concert, these results shed new light on the learning processes underlying social interaction with racial-in-group and out-group individuals.

Effects of Inventory Bias on Landslide Susceptibility Calculations

NASA Technical Reports Server (NTRS)

Stanley, T. A.; Kirschbaum, D. B.

2017-01-01

Many landslide inventories are known to be biased, especially inventories for large regions such as Oregon's SLIDO or NASA's Global Landslide Catalog. These biases must affect the results of empirically derived susceptibility models to some degree. We evaluated the strength of the susceptibility model distortion from postulated biases by truncating an unbiased inventory. We generated a synthetic inventory from an existing landslide susceptibility map of Oregon, then removed landslides from this inventory to simulate the effects of reporting biases likely to affect inventories in this region, namely population and infrastructure effects. Logistic regression models were fitted to the modified inventories. Then the process of biasing a susceptibility model was repeated with SLIDO data. We evaluated each susceptibility model with qualitative and quantitative methods. Results suggest that the effects of landslide inventory bias on empirical models should not be ignored, even if those models are, in some cases, useful. We suggest fitting models in well-documented areas and extrapolating across the study region as a possible approach to modeling landslide susceptibility with heavily biased inventories.

Effects of Inventory Bias on Landslide Susceptibility Calculations

NASA Technical Reports Server (NTRS)

Stanley, Thomas; Kirschbaum, Dalia B.

2017-01-01

Many landslide inventories are known to be biased, especially inventories for large regions such as Oregons SLIDO or NASAs Global Landslide Catalog. These biases must affect the results of empirically derived susceptibility models to some degree. We evaluated the strength of the susceptibility model distortion from postulated biases by truncating an unbiased inventory. We generated a synthetic inventory from an existing landslide susceptibility map of Oregon, then removed landslides from this inventory to simulate the effects of reporting biases likely to affect inventories in this region, namely population and infrastructure effects. Logistic regression models were fitted to the modified inventories. Then the process of biasing a susceptibility model was repeated with SLIDO data. We evaluated each susceptibility model with qualitative and quantitative methods. Results suggest that the effects of landslide inventory bias on empirical models should not be ignored, even if those models are, in some cases, useful. We suggest fitting models in well-documented areas and extrapolating across the study region as a possible approach to modelling landslide susceptibility with heavily biased inventories.

CALIPSO IIR Version 2 Level 1b calibrated radiances: analysis and reduction of residual biases in the Northern Hemisphere

NASA Astrophysics Data System (ADS)

Garnier, Anne; Trémas, Thierry; Pelon, Jacques; Lee, Kam-Pui; Nobileau, Delphine; Gross-Colzy, Lydwine; Pascal, Nicolas; Ferrage, Pascale; Scott, Noëlle A.

2018-04-01

Version 2 of the Level 1b calibrated radiances of the Imaging Infrared Radiometer (IIR) on board the Cloud-Aerosol Lidar and Infrared Satellite Observation (CALIPSO) satellite has been released recently. This new version incorporates corrections of small but systematic seasonal calibration biases previously revealed in Version 1 data products mostly north of 30° N. These biases - of different amplitudes in the three IIR channels 8.65 µm (IIR1), 10.6 µm (IIR2), and 12.05 µm (IIR3) - were made apparent by a striping effect in images of IIR inter-channel brightness temperature differences (BTDs) and through seasonal warm biases of nighttime IIR brightness temperatures in the 30-60° N latitude range. The latter were highlighted through observed and simulated comparisons with similar channels of the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Aqua spacecraft. To characterize the calibration biases affecting Version 1 data, a semi-empirical approach is developed, which is based on the in-depth analysis of the IIR internal calibration procedure in conjunction with observations such as statistical comparisons with similar MODIS/Aqua channels. Two types of calibration biases are revealed: an equalization bias affecting part of the individual IIR images and a global bias affecting the radiometric level of each image. These biases are observed only when the temperature of the instrument increases, and they are found to be functions of elapsed time since night-to-day transition, regardless of the season. Correction coefficients of Version 1 radiances could thus be defined and implemented in the Version 2 code. As a result, the striping effect seen in Version 1 is significantly attenuated in Version 2. Systematic discrepancies between nighttime and daytime IIR-MODIS BTDs in the 30-60° N latitude range in summer are reduced from 0.2 K in Version 1 to 0.1 K in Version 2 for IIR1-MODIS29. For IIR2-MODIS31 and IIR3-MODIS32, they are reduced from 0.4 K

Observational intensity bias associated with illness adjustment: cross sectional analysis of insurance claims

PubMed Central

Staiger, Douglas O; Sharp, Sandra M; Gottlieb, Daniel J; Bevan, Gwyn; McPherson, Klim; Welch, H Gilbert

2013-01-01

rates of visits by physicians introduce substantial bias when regional mortality and spending rates are adjusted for illness using comorbidity measures based on the observed number of diagnoses recorded in Medicare’s administrative database. Adjusting without correction for regional variation in visit rates tends to make regions with high rates of visits seem to have lower mortality and lower costs, and vice versa. Visit corrected comorbidity measures better explain variation in age, sex, and race mortality than observed measures, and reduce observational intensity bias. PMID:23430282

Study of the Dependence on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

NASA Technical Reports Server (NTRS)

Bandler, Simon

2011-01-01

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in the AC bias configuration. For x-ray photons at 6keV the AC biased pixel shows a best energy resolution of 3.7eV, which is about a factor of 2 worse than the energy resolution observed in identical DC-biased pixels. To better understand the reasons of this discrepancy, we investigated the detector performance as a function of temperature, bias working point and applied magnetic field. A strong periodic dependence of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recent weak-link behaviour observed inTES microcalorimeters.

Development of Spatiotemporal Bias-Correction Techniques for Downscaling GCM Predictions

NASA Astrophysics Data System (ADS)

Hwang, S.; Graham, W. D.; Geurink, J.; Adams, A.; Martinez, C. J.

2010-12-01

Accurately representing the spatial variability of precipitation is an important factor for predicting watershed response to climatic forcing, particularly in small, low-relief watersheds affected by convective storm systems. Although Global Circulation Models (GCMs) generally preserve spatial relationships between large-scale and local-scale mean precipitation trends, most GCM downscaling techniques focus on preserving only observed temporal variability on point by point basis, not spatial patterns of events. Downscaled GCM results (e.g., CMIP3 ensembles) have been widely used to predict hydrologic implications of climate variability and climate change in large snow-dominated river basins in the western United States (Diffenbaugh et al., 2008; Adam et al., 2009). However fewer applications to smaller rain-driven river basins in the southeastern US (where preserving spatial variability of rainfall patterns may be more important) have been reported. In this study a new method was developed to bias-correct GCMs to preserve both the long term temporal mean and variance of the precipitation data, and the spatial structure of daily precipitation fields. Forty-year retrospective simulations (1960-1999) from 16 GCMs were collected (IPCC, 2007; WCRP CMIP3 multi-model database: https://esg.llnl.gov:8443/), and the daily precipitation data at coarse resolution (i.e., 280km) were interpolated to 12km spatial resolution and bias corrected using gridded observations over the state of Florida (Maurer et al., 2002; Wood et al, 2002; Wood et al, 2004). In this method spatial random fields which preserved the observed spatial correlation structure of the historic gridded observations and the spatial mean corresponding to the coarse scale GCM daily rainfall were generated. The spatiotemporal variability of the spatio-temporally bias-corrected GCMs were evaluated against gridded observations, and compared to the original temporally bias-corrected and downscaled CMIP3 data for the

Large-scale galaxy bias

NASA Astrophysics Data System (ADS)

Jeong, Donghui; Desjacques, Vincent; Schmidt, Fabian

2018-01-01

Here, we briefly introduce the key results of the recent review (arXiv:1611.09787), whose abstract is as following. This review presents a comprehensive overview of galaxy bias, that is, the statistical relation between the distribution of galaxies and matter. We focus on large scales where cosmic density fields are quasi-linear. On these scales, the clustering of galaxies can be described by a perturbative bias expansion, and the complicated physics of galaxy formation is absorbed by a finite set of coefficients of the expansion, called bias parameters. The review begins with a detailed derivation of this very important result, which forms the basis of the rigorous perturbative description of galaxy clustering, under the assumptions of General Relativity and Gaussian, adiabatic initial conditions. Key components of the bias expansion are all leading local gravitational observables, which include the matter density but also tidal fields and their time derivatives. We hence expand the definition of local bias to encompass all these contributions. This derivation is followed by a presentation of the peak-background split in its general form, which elucidates the physical meaning of the bias parameters, and a detailed description of the connection between bias parameters and galaxy (or halo) statistics. We then review the excursion set formalism and peak theory which provide predictions for the values of the bias parameters. In the remainder of the review, we consider the generalizations of galaxy bias required in the presence of various types of cosmological physics that go beyond pressureless matter with adiabatic, Gaussian initial conditions: primordial non-Gaussianity, massive neutrinos, baryon-CDM isocurvature perturbations, dark energy, and modified gravity. Finally, we discuss how the description of galaxy bias in the galaxies' rest frame is related to clustering statistics measured from the observed angular positions and redshifts in actual galaxy catalogs.

Variable Autosomal and X Divergence Near and Far from Genes Affects Estimates of Male Mutation Bias in Great Apes.

PubMed

Narang, Pooja; Wilson Sayres, Melissa A

2016-12-31

Male mutation bias, when more mutations are passed on via the male germline than via the female germline, is observed across mammals. One common way to infer the magnitude of male mutation bias, α, is to compare levels of neutral sequence divergence between genomic regions that spend different amounts of time in the male and female germline. For great apes, including human, we show that estimates of divergence are reduced in putatively unconstrained regions near genes relative to unconstrained regions far from genes. Divergence increases with increasing distance from genes on both the X chromosome and autosomes, but increases faster on the X chromosome than autosomes. As a result, ratios of X/A divergence increase with increasing distance from genes and corresponding estimates of male mutation bias are significantly higher in intergenic regions near genes versus far from genes. Future studies in other species will need to carefully consider the effect that genomic location will have on estimates of male mutation bias. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

BallotMaps: detecting name bias in alphabetically ordered ballot papers.

PubMed

Wood, Jo; Badawood, Donia; Dykes, Jason; Slingsby, Aidan

2011-12-01

The relationship between candidates' position on a ballot paper and vote rank is explored in the case of 5000 candidates for the UK 2010 local government elections in the Greater London area. This design study uses hierarchical spatially arranged graphics to represent two locations that affect candidates at very different scales: the geographical areas for which they seek election and the spatial location of their names on the ballot paper. This approach allows the effect of position bias to be assessed; that is, the degree to which the position of a candidate's name on the ballot paper influences the number of votes received by the candidate, and whether this varies geographically. Results show that position bias was significant enough to influence rank order of candidates, and in the case of many marginal electoral wards, to influence who was elected to government. Position bias was observed most strongly for Liberal Democrat candidates but present for all major political parties. Visual analysis of classification of candidate names by ethnicity suggests that this too had an effect on votes received by candidates, in some cases overcoming alphabetic name bias. The results found contradict some earlier research suggesting that alphabetic name bias was not sufficiently significant to affect electoral outcome and add new evidence for the geographic and ethnicity influences on voting behaviour. The visual approach proposed here can be applied to a wider range of electoral data and the patterns identified and hypotheses derived from them could have significant implications for the design of ballot papers and the conduct of fair elections. © 2010 IEEE

Lost in translation: Review of identification bias, translation bias and research waste in dentistry.

PubMed

Layton, Danielle M; Clarke, Michael

2016-01-01

To review how articles are retrieved from bibliographic databases, what article identification and translation problems have affected research, and how these problems can contribute to research waste and affect clinical practice. This literature review sought and appraised articles regarding identification- and translation-bias in the medical and dental literature, which limit the ability of users to find research articles and to use these in practice. Articles can be retrieved from bibliographic databases by performing a word or index-term (for example, MeSH for MEDLINE) search. Identification of articles is challenging when it is not clear which words are most relevant, and which terms have been allocated to indexing fields. Poor reporting quality of abstracts and articles has been reported across the medical literature at large. Specifically in dentistry, research regarding time-to-event survival analyses found the allocation of MeSH terms to be inconsistent and inaccurate, important words were omitted from abstracts by authors, and the quality of reporting in the body of articles was generally poor. These shortcomings mean that articles will be difficult to identify, and difficult to understand if found. Use of specialized electronic search strategies can decrease identification bias, and use of tailored reporting guidelines can decrease translation bias. Research that cannot be found, or cannot be used results in research waste, and undermines clinical practice. Identification- and translation-bias have been shown to affect time-to-event dental articles, are likely affect other fields of research, and are largely unrecognized by authors and evidence seekers alike. By understanding that the problems exist, solutions can be sought to improve identification and translation of our research. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Methodological approaches in analysing observational data: A practical example on how to address clustering and selection bias.

PubMed

Trutschel, Diana; Palm, Rebecca; Holle, Bernhard; Simon, Michael

2017-11-01

Because not every scientific question on effectiveness can be answered with randomised controlled trials, research methods that minimise bias in observational studies are required. Two major concerns influence the internal validity of effect estimates: selection bias and clustering. Hence, to reduce the bias of the effect estimates, more sophisticated statistical methods are needed. To introduce statistical approaches such as propensity score matching and mixed models into representative real-world analysis and to conduct the implementation in statistical software R to reproduce the results. Additionally, the implementation in R is presented to allow the results to be reproduced. We perform a two-level analytic strategy to address the problems of bias and clustering: (i) generalised models with different abilities to adjust for dependencies are used to analyse binary data and (ii) the genetic matching and covariate adjustment methods are used to adjust for selection bias. Hence, we analyse the data from two population samples, the sample produced by the matching method and the full sample. The different analysis methods in this article present different results but still point in the same direction. In our example, the estimate of the probability of receiving a case conference is higher in the treatment group than in the control group. Both strategies, genetic matching and covariate adjustment, have their limitations but complement each other to provide the whole picture. The statistical approaches were feasible for reducing bias but were nevertheless limited by the sample used. For each study and obtained sample, the pros and cons of the different methods have to be weighted. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Tropospheric GOM at the Pic du Midi Observatory-Correcting Bias in Denuder Based Observations.

PubMed

Marusczak, Nicolas; Sonke, Jeroen E; Fu, Xuewu; Jiskra, Martin

2017-01-17

Gaseous elemental mercury (GEM, Hg) emissions are transformed to divalent reactive Hg (RM) forms throughout the troposphere and stratosphere. RM is often operationally quantified as the sum of particle bound Hg (PBM) and gaseous oxidized Hg (GOM). The measurement of GOM and PBM is challenging and under mounting criticism. Here we intercompare six months of automated GOM and PBM measurements using a Tekran (TK) KCl-coated denuder and quartz regenerable particulate filter method (GOM TK , PBM TK , and RM TK ) with RM CEM collected on cation exchange membranes (CEMs) at the high altitude Pic du Midi Observatory. We find that RM TK is systematically lower by a factor of 1.3 than RM CEM . We observe a significant relationship between GOM TK (but not PBM TK ) and Tekran flush TK blanks suggesting significant loss (36%) of labile GOM TK from the denuder or inlet. Adding the flush TK blank to RM TK results in good agreement with RM CEM (slope = 1.01, r 2 = 0.90) suggesting we can correct bias in RM TK and GOM TK . We provide a bias corrected (*) Pic du Midi data set for 2012-2014 that shows GOM* and RM* levels in dry free tropospheric air of 198 ± 57 and 229 ± 58 pg m -3 which agree well with in-flight observed RM and with model based GOM and RM estimates.

The Impact of Experience on Affective Responses during Action Observation.

PubMed

Kirsch, Louise P; Snagg, Arielle; Heerey, Erin; Cross, Emily S

2016-01-01

Perceiving others in action elicits affective and aesthetic responses in observers. The present study investigates the extent to which these responses relate to an observer's general experience with observed movements. Facial electromyographic (EMG) responses were recorded in experienced dancers and non-dancers as they watched short videos of movements performed by professional ballet dancers. Responses were recorded from the corrugator supercilii (CS) and zygomaticus major (ZM) muscles, both of which show engagement during the observation of affect-evoking stimuli. In the first part of the experiment, participants passively watched the videos while EMG data were recorded. In the second part, they explicitly rated how much they liked each movement. Results revealed a relationship between explicit affective judgments of the movements and facial muscle activation only among those participants who were experienced with the movements. Specifically, CS activity was higher for disliked movements and ZM activity was higher for liked movements among dancers but not among non-dancers. The relationship between explicit liking ratings and EMG data in experienced observers suggests that facial muscles subtly echo affective judgments even when viewing actions that are not intentionally emotional in nature, thus underscoring the potential of EMG as a method to examine subtle shifts in implicit affective responses during action observation.

The Role of Response Bias in Perceptual Learning

PubMed Central

2015-01-01

Sensory judgments improve with practice. Such perceptual learning is often thought to reflect an increase in perceptual sensitivity. However, it may also represent a decrease in response bias, with unpracticed observers acting in part on a priori hunches rather than sensory evidence. To examine whether this is the case, 55 observers practiced making a basic auditory judgment (yes/no amplitude-modulation detection or forced-choice frequency/amplitude discrimination) over multiple days. With all tasks, bias was present initially, but decreased with practice. Notably, this was the case even on supposedly “bias-free,” 2-alternative forced-choice, tasks. In those tasks, observers did not favor the same response throughout (stationary bias), but did favor whichever response had been correct on previous trials (nonstationary bias). Means of correcting for bias are described. When applied, these showed that at least 13% of perceptual learning on a forced-choice task was due to reduction in bias. In other situations, changes in bias were shown to obscure the true extent of learning, with changes in estimated sensitivity increasing once bias was corrected for. The possible causes of bias and the implications for our understanding of perceptual learning are discussed. PMID:25867609

How does dynamical downscaling affect model biases and future projections of explosive extratropical cyclones along North America's Atlantic coast?

NASA Astrophysics Data System (ADS)

Seiler, C.; Zwiers, F. W.; Hodges, K. I.; Scinocca, J. F.

2018-01-01

Explosive extratropical cyclones (EETCs) are rapidly intensifying low pressure systems that generate severe weather along North America's Atlantic coast. Global climate models (GCMs) tend to simulate too few EETCs, perhaps partly due to their coarse horizontal resolution and poorly resolved moist diabatic processes. This study explores whether dynamical downscaling can reduce EETC frequency biases, and whether this affects future projections of storms along North America's Atlantic coast. A regional climate model (CanRCM4) is forced with the CanESM2 GCM for the periods 1981 to 2000 and 2081 to 2100. EETCs are tracked from relative vorticity using an objective feature tracking algorithm. CanESM2 simulates 38% fewer EETC tracks compared to reanalysis data, which is consistent with a negative Eady growth rate bias (-0.1 day^{-1}). Downscaling CanESM2 with CanRCM4 increases EETC frequency by one third, which reduces the frequency bias to -22%, and increases maximum EETC precipitation by 22%. Anthropogenic greenhouse gas forcing is projected to decrease EETC frequency (-15%, -18%) and Eady growth rate (-0.2 day^{-1}, -0.2 day^{-1}), and increase maximum EETC precipitation (46%, 52%) in CanESM2 and CanRCM4, respectively. The limited effect of dynamical downscaling on EETC frequency projections is consistent with the lack of impact on the maximum Eady growth rate. The coarse spatial resolution of GCMs presents an important limitation for simulating extreme ETCs, but Eady growth rate biases are likely just as relevant. Further bias reductions could be achieved by addressing processes that lead to an underestimation of lower tropospheric meridional temperature gradients.

Direct estimation and correction of bias from temporally variable non-stationary noise in a channelized Hotelling model observer.

PubMed

Fetterly, Kenneth A; Favazza, Christopher P

2016-08-07

Channelized Hotelling model observer (CHO) methods were developed to assess performance of an x-ray angiography system. The analytical methods included correction for known bias error due to finite sampling. Detectability indices ([Formula: see text]) corresponding to disk-shaped objects with diameters in the range 0.5-4 mm were calculated. Application of the CHO for variable detector target dose (DTD) in the range 6-240 nGy frame(-1) resulted in [Formula: see text] estimates which were as much as 2.9×  greater than expected of a quantum limited system. Over-estimation of [Formula: see text] was presumed to be a result of bias error due to temporally variable non-stationary noise. Statistical theory which allows for independent contributions of 'signal' from a test object (o) and temporally variable non-stationary noise (ns) was developed. The theory demonstrates that the biased [Formula: see text] is the sum of the detectability indices associated with the test object [Formula: see text] and non-stationary noise ([Formula: see text]). Given the nature of the imaging system and the experimental methods, [Formula: see text] cannot be directly determined independent of [Formula: see text]. However, methods to estimate [Formula: see text] independent of [Formula: see text] were developed. In accordance with the theory, [Formula: see text] was subtracted from experimental estimates of [Formula: see text], providing an unbiased estimate of [Formula: see text]. Estimates of [Formula: see text] exhibited trends consistent with expectations of an angiography system that is quantum limited for high DTD and compromised by detector electronic readout noise for low DTD conditions. Results suggest that these methods provide [Formula: see text] estimates which are accurate and precise for [Formula: see text]. Further, results demonstrated that the source of bias was detector electronic readout noise. In summary, this work presents theory and methods to test for the

Solar array/spacecraft biasing

NASA Technical Reports Server (NTRS)

Fitzgerald, D. J.

1981-01-01

Biasing techniques and their application to the control of spacecraft potential is discussed. Normally when a spacecraft is operated with ion thrusters, the spacecraft will be 10-20 volts negative of the surrounding plasma. This will affect scientific measurements and will allow ions from the charge-exchange plasma to bombard the spacecraft surfaces with a few tens of volts of energy. This condition may not be tolerable. A proper bias system is described that can bring the spacecraft to or near the potential of the surrounding plasma.

On the Limitations of Variational Bias Correction

NASA Technical Reports Server (NTRS)

Moradi, Isaac; Mccarty, Will; Gelaro, Ronald

2018-01-01

Satellite radiances are the largest dataset assimilated into Numerical Weather Prediction (NWP) models, however the data are subject to errors and uncertainties that need to be accounted for before assimilating into the NWP models. Variational bias correction uses the time series of observation minus background to estimate the observations bias. This technique does not distinguish between the background error, forward operator error, and observations error so that all these errors are summed up together and counted as observation error. We identify some sources of observations errors (e.g., antenna emissivity, non-linearity in the calibration, and antenna pattern) and show the limitations of variational bias corrections on estimating these errors.

The impact of uncertain threat on affective bias: Individual differences in response to ambiguity.

PubMed

Neta, Maital; Cantelon, Julie; Haga, Zachary; Mahoney, Caroline R; Taylor, Holly A; Davis, F Caroline

2017-12-01

Individuals who operate under highly stressful conditions (e.g., military personnel and first responders) are often faced with the challenge of quickly interpreting ambiguous information in uncertain and threatening environments. When faced with ambiguity, it is likely adaptive to view potentially dangerous stimuli as threatening until contextual information proves otherwise. One laboratory-based paradigm that can be used to simulate uncertain threat is known as threat of shock (TOS), in which participants are told that they might receive mild but unpredictable electric shocks while performing an unrelated task. The uncertainty associated with this potential threat induces a state of emotional arousal that is not overwhelmingly stressful, but has widespread-both adaptive and maladaptive-effects on cognitive and affective function. For example, TOS is thought to enhance aversive processing and abolish positivity bias. Importantly, in certain situations (e.g., when walking home alone at night), this anxiety can promote an adaptive state of heightened vigilance and defense mobilization. In the present study, we used TOS to examine the effects of uncertain threat on valence bias, or the tendency to interpret ambiguous social cues as positive or negative. As predicted, we found that heightened emotional arousal elicited by TOS was associated with an increased tendency to interpret ambiguous cues negatively. Such negative interpretations are likely adaptive in situations in which threat detection is critical for survival and should override an individual's tendency to interpret ambiguity positively in safe contexts. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

NASA Technical Reports Server (NTRS)

Gottardi, L.; Bruijn, M.; denHartog, R.; Hoevers, H.; deKorte, P.; vanderKuur, J.; Linderman, M.; Adams, J.; Bailey, C.; Bandler, S.;

Biased recognition of facial affect in patients with major depressive disorder reflects clinical state.

PubMed

Münkler, Paula; Rothkirch, Marcus; Dalati, Yasmin; Schmack, Katharina; Sterzer, Philipp

2015-01-01

Cognitive theories of depression posit that perception is negatively biased in depressive disorder. Previous studies have provided empirical evidence for this notion, but left open the question whether the negative perceptual bias reflects a stable trait or the current depressive state. Here we investigated the stability of negatively biased perception over time. Emotion perception was examined in patients with major depressive disorder (MDD) and healthy control participants in two experiments. In the first experiment subjective biases in the recognition of facial emotional expressions were assessed. Participants were presented with faces that were morphed between sad and neutral and happy expressions and had to decide whether the face was sad or happy. The second experiment assessed automatic emotion processing by measuring the potency of emotional faces to gain access to awareness using interocular suppression. A follow-up investigation using the same tests was performed three months later. In the emotion recognition task, patients with major depression showed a shift in the criterion for the differentiation between sad and happy faces: In comparison to healthy controls, patients with MDD required a greater intensity of the happy expression to recognize a face as happy. After three months, this negative perceptual bias was reduced in comparison to the control group. The reduction in negative perceptual bias correlated with the reduction of depressive symptoms. In contrast to previous work, we found no evidence for preferential access to awareness of sad vs. happy faces. Taken together, our results indicate that MDD-related perceptual biases in emotion recognition reflect the current clinical state rather than a stable depressive trait.

The contribution of natural variability to GCM bias: Can we effectively bias-correct climate projections?

NASA Astrophysics Data System (ADS)

McAfee, S. A.; DeLaFrance, A.

2017-12-01

Investigating the impacts of climate change often entails using projections from inherently imperfect general circulation models (GCMs) to drive models that simulate biophysical or societal systems in great detail. Error or bias in the GCM output is often assessed in relation to observations, and the projections are adjusted so that the output from impacts models can be compared to historical or observed conditions. Uncertainty in the projections is typically accommodated by running more than one future climate trajectory to account for differing emissions scenarios, model simulations, and natural variability. The current methods for dealing with error and uncertainty treat them as separate problems. In places where observed and/or simulated natural variability is large, however, it may not be possible to identify a consistent degree of bias in mean climate, blurring the lines between model error and projection uncertainty. Here we demonstrate substantial instability in mean monthly temperature bias across a suite of GCMs used in CMIP5. This instability is greatest in the highest latitudes during the cool season, where shifts from average temperatures below to above freezing could have profound impacts. In models with the greatest degree of bias instability, the timing of regional shifts from below to above average normal temperatures in a single climate projection can vary by about three decades, depending solely on the degree of bias assessed. This suggests that current bias correction methods based on comparison to 20- or 30-year normals may be inappropriate, particularly in the polar regions.

Does Ethnic Bias Affect Kindergarten Teachers' School Entry Recommendations?

ERIC Educational Resources Information Center

Becker, Birgit; Tuppat, Julia

2018-01-01

Background: Ethnic educational inequality is present in almost all Western societies. One possible explanation for the persisting disadvantages of children from immigrant family backgrounds is discrimination. Individual ethnic discrimination has been reported in the form of ethnic bias in school teachers' evaluations and recommendations. Children…

Expectancy biases in fear and anxiety and their link to biases in attention.

PubMed

Aue, Tatjana; Okon-Singer, Hadas

2015-12-01

Healthy individuals often exhibit prioritized processing of aversive information, as manifested in enhanced orientation of attention to threatening stimuli compared with neutral items. In contrast to this adaptive behavior, anxious, fearful, and phobic individuals show exaggerated attention biases to threat. In addition, they overestimate the likelihood of encountering their feared stimulus and the severity of the consequences; both are examples of expectancy biases. The co-occurrence of attention and expectancy biases in fear and anxiety raises the question about causal influences. Herein, we summarize findings related to expectancy biases in fear and anxiety, and their association with attention biases. We suggest that evidence calls for more comprehensive research strategies in the investigation of mutual influences between expectancy and attention biases, as well as their combined effects on fear and anxiety. Moreover, both types of bias need to be related to other types of distorted information processing commonly observed in fear and anxiety (e.g., memory and interpretation biases). Finally, we propose new research directions that may be worth considering in developing more effective treatments for anxiety disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

Developmental Changes in the Whole Number Bias

ERIC Educational Resources Information Center

Braithwaite, David W.; Siegler, Robert S.

2017-01-01

Many students' knowledge of fractions is adversely affected by whole number bias, the tendency to focus on the separate whole number components (numerator and denominator) of a fraction rather than on the fraction's integrated magnitude (ratio of numerator to denominator). Although whole number bias appears early in the fraction learning process…

Evidence of Cognitive Bias in Decision Making Around Implantable-Cardioverter Defibrillators: A Qualitative Framework Analysis.

PubMed

Matlock, Daniel D; Jones, Jacqueline; Nowels, Carolyn T; Jenkins, Amy; Allen, Larry A; Kutner, Jean S

2017-11-01

Studies have demonstrated that patients with primary prevention implantable cardioverter-defibrillators (ICDs) often misunderstand the ICD. Advances in behavioral economics demonstrate that some misunderstandings may be due to cognitive biases. We aimed to explore the influence of cognitive bias on ICD decision making. We used a qualitative framework analysis including 9 cognitive biases: affect heuristic, affective forecasting, anchoring, availability, default effects, halo effects, optimism bias, framing effects, and state dependence. We interviewed 48 patients from 4 settings in Denver. The majority were male (n = 32). Overall median age was 61 years. We found frequent evidence for framing, default, and halo effects; some evidence of optimism bias, affect heuristic, state dependence, anchoring and availability bias; and little or no evidence of affective forecasting. Framing effects were apparent in overestimation of benefits and downplaying or omitting potential harms. We found evidence of cognitive bias in decision making for ICD implantation. The majority of these biases appeared to encourage ICD treatment. Published by Elsevier Inc.

Observation of electric potential in organic thin-film transistor by bias-applied hard X-ray photoemission spectroscopy

NASA Astrophysics Data System (ADS)

Watanabe, Takeshi; Tada, Keisuke; Yasuno, Satoshi; Oji, Hiroshi; Yoshimoto, Noriyuki; Hirosawa, Ichiro

2016-03-01

The effect of gate voltage on electric potential in a pentacene (PEN) layer was studied by hard X-ray photoelectron spectroscopy under a bias voltage. It was observed that applying a negative gate voltage substantially increases the width of a C 1s peak. This suggested that injected and accumulated carriers in an organic thin film transistor channel modified the potential depth profile in PEN. It was also observed that the C 1s kinetic energy tends to increase monotonically with threshold voltage.

Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter.

PubMed

Gottardi, L; Adams, J; Bailey, C; Bandler, S; Bruijn, M; Chervenak, J; Eckart, M; Finkbeiner, F; den Hartog, R; Hoevers, H; Kelley, R; Kilbourne, C; de Korte, P; van der Kuur, J; Lindeman, M; Porter, F; Sadlier, J; Smith, S

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Δ E FWHM =3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

Practical Bias Correction in Aerial Surveys of Large Mammals: Validation of Hybrid Double-Observer with Sightability Method against Known Abundance of Feral Horse (Equus caballus) Populations

PubMed Central

2016-01-01

Reliably estimating wildlife abundance is fundamental to effective management. Aerial surveys are one of the only spatially robust tools for estimating large mammal populations, but statistical sampling methods are required to address detection biases that affect accuracy and precision of the estimates. Although various methods for correcting aerial survey bias are employed on large mammal species around the world, these have rarely been rigorously validated. Several populations of feral horses (Equus caballus) in the western United States have been intensively studied, resulting in identification of all unique individuals. This provided a rare opportunity to test aerial survey bias correction on populations of known abundance. We hypothesized that a hybrid method combining simultaneous double-observer and sightability bias correction techniques would accurately estimate abundance. We validated this integrated technique on populations of known size and also on a pair of surveys before and after a known number was removed. Our analysis identified several covariates across the surveys that explained and corrected biases in the estimates. All six tests on known populations produced estimates with deviations from the known value ranging from -8.5% to +13.7% and <0.7 standard errors. Precision varied widely, from 6.1% CV to 25.0% CV. In contrast, the pair of surveys conducted around a known management removal produced an estimated change in population between the surveys that was significantly larger than the known reduction. Although the deviation between was only 9.1%, the precision estimate (CV = 1.6%) may have been artificially low. It was apparent that use of a helicopter in those surveys perturbed the horses, introducing detection error and heterogeneity in a manner that could not be corrected by our statistical models. Our results validate the hybrid method, highlight its potentially broad applicability, identify some limitations, and provide insight and guidance

Practical Bias Correction in Aerial Surveys of Large Mammals: Validation of Hybrid Double-Observer with Sightability Method against Known Abundance of Feral Horse (Equus caballus) Populations.

PubMed

Lubow, Bruce C; Ransom, Jason I

2016-01-01

Reliably estimating wildlife abundance is fundamental to effective management. Aerial surveys are one of the only spatially robust tools for estimating large mammal populations, but statistical sampling methods are required to address detection biases that affect accuracy and precision of the estimates. Although various methods for correcting aerial survey bias are employed on large mammal species around the world, these have rarely been rigorously validated. Several populations of feral horses (Equus caballus) in the western United States have been intensively studied, resulting in identification of all unique individuals. This provided a rare opportunity to test aerial survey bias correction on populations of known abundance. We hypothesized that a hybrid method combining simultaneous double-observer and sightability bias correction techniques would accurately estimate abundance. We validated this integrated technique on populations of known size and also on a pair of surveys before and after a known number was removed. Our analysis identified several covariates across the surveys that explained and corrected biases in the estimates. All six tests on known populations produced estimates with deviations from the known value ranging from -8.5% to +13.7% and <0.7 standard errors. Precision varied widely, from 6.1% CV to 25.0% CV. In contrast, the pair of surveys conducted around a known management removal produced an estimated change in population between the surveys that was significantly larger than the known reduction. Although the deviation between was only 9.1%, the precision estimate (CV = 1.6%) may have been artificially low. It was apparent that use of a helicopter in those surveys perturbed the horses, introducing detection error and heterogeneity in a manner that could not be corrected by our statistical models. Our results validate the hybrid method, highlight its potentially broad applicability, identify some limitations, and provide insight and guidance

Does observer bias contribute to variations in the rate of retinopathy of prematurity between centres?

PubMed

Darlow, Brian A; Elder, Mark J; Horwood, L John; Donoghue, Deborah A; Henderson-Smart, David J

2008-01-01

We aimed to indirectly assess the contribution from observer bias to between centre variability in the incidence of acute retinopathy of prematurity (ROP). The Australian and New Zealand Neonatal Network (ANZNN) collected data on the highest stage of acute ROP in either eye in 2286 infants born at less than 29 weeks in 1998-1999 and cared for in one of 25 neonatal intensive care units (NICUs). Chi-squared analysis was used to detect differences in the proportion of stages of ROP for each neonatal intensive care unit. These proportions were compared with those reported in two large studies of treatment for ROP. The incidence of acute ROP in the ANZNN cohort was 42% and the ratio of stage 1:2:3 ROP was 1.5:1.9:1. There was considerable variation in both the incidence of acute ROP and the proportions with stage 1:2:3 ROP between centres. A chi-squared test determined that the assignment of stages 1, 2 and 3/4 ROP was not independent of centre (chi(2)(48) = 165.2; P < 0.0001). Treatment of stage 3 ROP varied between 15% and 120%, indicating some eyes were treated at less than stage 3. The data are highly suggestive of observer bias contributing to the observed between centre variation in the incidence of acute ROP. In neonatal intervention studies where acute ROP is an outcome it would seem important to have an accreditation process for examining ophthalmologists, and there are similar arguments for neonatal networks which collect these data.

Cognitive determinants of affective forecasting errors

PubMed Central

Hoerger, Michael; Quirk, Stuart W.; Lucas, Richard E.; Carr, Thomas H.

2011-01-01

Often to the detriment of human decision making, people are prone to an impact bias when making affective forecasts, overestimating the emotional consequences of future events. The cognitive processes underlying the impact bias, and methods for correcting it, have been debated and warrant further exploration. In the present investigation, we examined both individual differences and contextual variables associated with cognitive processing in affective forecasting for an election. Results showed that the perceived importance of the event and working memory capacity were both associated with an increased impact bias for some participants, whereas retrieval interference had no relationship with bias. Additionally, an experimental manipulation effectively reduced biased forecasts, particularly among participants who were most distracted thinking about peripheral life events. These findings have direct theoretical implications for understanding the impact bias, highlight the importance of individual differences in affective forecasting, and have ramifications for future decision making research. The possible functional role of the impact bias is discussed within the context of evolutionary psychology. PMID:21912580

Understanding Implicit Bias: What Educators Should Know

ERIC Educational Resources Information Center

Staats, Cheryl

2016-01-01

The desire to ensure the best for children is precisely why educators should become aware of the concept of implicit bias: the attitudes or stereotypes that affect our understanding, actions, and decisions in an unconscious manner. Operating outside of our conscious awareness, implicit biases are pervasive, and they can challenge even the most…

Developmental Changes in the Whole Number Bias

ERIC Educational Resources Information Center

Braithwaite, David W.; Siegler, Robert S.

2018-01-01

Many students' knowledge of fractions is adversely affected by whole number bias, the tendency to focus on the separate whole number components (numerator and denominator) of a fraction rather than on the fraction's magnitude (ratio of numerator to denominator). Although whole number bias appears early in the fraction learning process and under…

Content specificity of attentional bias to threat in post-traumatic stress disorder.

PubMed

Zinchenko, A; Al-Amin, M M; Alam, M M; Mahmud, W; Kabir, N; Reza, H M; Burne, T H J

2017-08-01

Attentional bias to affective information and reduced cognitive control may maintain the symptoms of post-traumatic stress disorder (PTSD) and impair cognitive functioning. However, the role of content specificity of affective stimuli (e.g., trauma-related, emotional trauma-unrelated) in the observed attentional bias and cognitive control is less clear, as this has not been tested simultaneously before. Therefore, we examined the content specificity of attentional bias to threat in PTSD. PTSD participants (survivors of a multistory factory collapse, n=30) and matched controls (n=30) performed an Eriksen Flanker task. They identified the direction of a centrally presented target arrow, which was flanked by several task-irrelevant distractor arrows pointed to the same (congruent) or opposite direction (incongruent). Additionally, participants were presented with a picture of a face (neutral, emotional) or building (neutral=normal, emotional=collapsed multistory factory) as a task-irrelevant background image. We found that PTSD participants produced overall larger conflict effects and longer reaction times (RT) to emotional than to neutral stimuli relative to their healthy counterparts. Moreover, PTSD, but not healthy participants showed a stimulus specific dissociation in processing emotional stimuli. Emotional faces elicited longer RTs compared to neutral faces, while emotional buildings elicited faster responses, compared to neutral buildings. PTSD patients show a content-sensitive attentional bias to emotional information and impaired cognitive control. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Statistical Analysis of Reviewer Agreement and Bias in Evaluating Medical Abstracts 1

PubMed Central

Cicchetti, Domenic V.; Conn, Harold O.

1976-01-01

Observer variability affects virtually all aspects of clinical medicine and investigation. One important aspect, not previously examined, is the selection of abstracts for presentation at national medical meetings. In the present study, 109 abstracts, submitted to the American Association for the Study of Liver Disease, were evaluated by three “blind” reviewers for originality, design-execution, importance, and overall scientific merit. Of the 77 abstracts rated for all parameters by all observers, interobserver agreement ranged between 81 and 88%. However, corresponding intraclass correlations varied between 0.16 (approaching statistical significance) and 0.37 (p < 0.01). Specific tests of systematic differences in scoring revealed statistically significant levels of observer bias on most of the abstract components. Moreover, the mean differences in interobserver ratings were quite small compared to the standard deviations of these differences. These results emphasize the importance of evaluating the simple percentage of rater agreement within the broader context of observer variability and systematic bias. PMID:997596

How trait anxiety, interpretation bias and memory affect acquired fear in children learning about new animals.

PubMed

Field, Zoë C; Field, Andy P

2013-06-01

Cognitive models of vulnerability to anxiety propose that information processing biases such as interpretation bias play a part in the etiology and maintenance of anxiety disorders. However, at present little is known about the role of memory in information processing accounts of child anxiety. The current study investigates the relationships between interpretation biases, memory and fear responses when learning about new stimuli. Children (aged 8-11 years) were presented with ambiguous information regarding a novel animal, and their fear, interpretation bias, and memory for the information was measured. The main findings were: (1) trait anxiety and interpretation bias significantly predicted acquired fear; (2) interpretation bias did not significantly mediate the relationship between trait anxiety and acquired fear; (3) interpretation bias appeared to be a more important predictor of acquired fear than trait anxiety per se; and (4) the relationship between interpretation bias and acquired fear was not mediated by the number of negative memories but was mediated by the number of positive and false-positive memories. The findings suggest that information processing models of child anxiety need to explain the role of positive memory in the formation of fear responses.

Ranking Bias in Association Studies

PubMed Central

Jeffries, Neal O.

2009-01-01

Background It is widely appreciated that genomewide association studies often yield overestimates of the association of a marker with disease when attention focuses upon the marker showing the strongest relationship. For example, in a case-control setting the largest (in absolute value) estimated odds ratio has been found to typically overstate the association as measured in a second, independent set of data. The most common reason given for this observation is that the choice of the most extreme test statistic is often conditional upon first observing a significant p value associated with the marker. A second, less appreciated reason is described here. Under common circumstances it is the multiple testing of many markers and subsequent focus upon those with most extreme test statistics (i.e. highly ranked results) that leads to bias in the estimated effect sizes. Conclusions This bias, termed ranking bias, is separate from that arising from conditioning on a significant p value and may often be a more important factor in generating bias. An analytic description of this bias, simulations demonstrating its extent, and identification of some factors leading to its exacerbation are presented. PMID:19172085

Evaluating species richness: biased ecological inference results from spatial heterogeneity in species detection probabilities

USGS Publications Warehouse

McNew, Lance B.; Handel, Colleen M.

2015-01-01

Accurate estimates of species richness are necessary to test predictions of ecological theory and evaluate biodiversity for conservation purposes. However, species richness is difficult to measure in the field because some species will almost always be overlooked due to their cryptic nature or the observer's failure to perceive their cues. Common measures of species richness that assume consistent observability across species are inviting because they may require only single counts of species at survey sites. Single-visit estimation methods ignore spatial and temporal variation in species detection probabilities related to survey or site conditions that may confound estimates of species richness. We used simulated and empirical data to evaluate the bias and precision of raw species counts, the limiting forms of jackknife and Chao estimators, and multi-species occupancy models when estimating species richness to evaluate whether the choice of estimator can affect inferences about the relationships between environmental conditions and community size under variable detection processes. Four simulated scenarios with realistic and variable detection processes were considered. Results of simulations indicated that (1) raw species counts were always biased low, (2) single-visit jackknife and Chao estimators were significantly biased regardless of detection process, (3) multispecies occupancy models were more precise and generally less biased than the jackknife and Chao estimators, and (4) spatial heterogeneity resulting from the effects of a site covariate on species detection probabilities had significant impacts on the inferred relationships between species richness and a spatially explicit environmental condition. For a real dataset of bird observations in northwestern Alaska, the four estimation methods produced different estimates of local species richness, which severely affected inferences about the effects of shrubs on local avian richness. Overall, our results

Attentional bias to negative affect moderates negative affect's relationship with smoking abstinence.

PubMed

Etcheverry, Paul E; Waters, Andrew J; Lam, Cho; Correa-Fernandez, Virmarie; Vidrine, Jennifer Irvin; Cinciripini, Paul M; Wetter, David W

2016-08-01

To examine whether initial orienting (IO) and inability to disengage (ITD) attention from negative affective stimuli moderate the association of negative affect with smoking abstinence during a quit attempt. Data were from a longitudinal cohort study of smoking cessation (N = 424). A negative affect modified Stroop task was administered 1 week before and on quit day to measure IO and ITD. Ecological Momentary Assessments were used to create negative affect intercepts and linear slopes for the week before quitting and on quit day. Quit day and long-term abstinence measures were collected. Continuation ratio logit model analyses found significant interactions for prequit negative affect slope with prequit ITD, odds ratio (OR) = 0.738 (0.57, 0.96), p = .02, and for quit day negative affect intercept with quit day ITD, OR = 0.62 (0.41, 950), p = .03, predicting abstinence. The Prequit Negative Affect Intercept × Prequit IO interaction predicting quit day abstinence was significant, OR = 1.42 (1.06, 1.90), p = .02, as was the Quit Day Negative Affect Slope × Quit Day IO interaction predicting long-term abstinence, OR = 1.45 (1.02, 2.08), p = .04. The hypothesis that the association of negative affect with smoking abstinence would be moderated by ITD was generally supported. Among individuals with high ITD, negative affect was inversely related to abstinence, but unrelated to abstinence among individuals with lower levels of ITD. Unexpectedly, among individuals with low IO, negative affect was inversely related to abstinence, but unrelated to abstinence among individuals with higher levels of ITD. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Use of the Magnetic Field for Improving Gyroscopes’ Biases Estimation

PubMed Central

Munoz Diaz, Estefania; de Ponte Müller, Fabian; García Domínguez, Juan Jesús

2017-01-01

An accurate orientation is crucial to a satisfactory position in pedestrian navigation. The orientation estimation, however, is greatly affected by errors like the biases of gyroscopes. In order to minimize the error in the orientation, the biases of gyroscopes must be estimated and subtracted. In the state of the art it has been proposed, but not proved, that the estimation of the biases can be accomplished using magnetic field measurements. The objective of this work is to evaluate the effectiveness of using magnetic field measurements to estimate the biases of medium-cost micro-electromechanical sensors (MEMS) gyroscopes. We carry out the evaluation with experiments that cover both, quasi-error-free turn rate and magnetic measurements and medium-cost MEMS turn rate and magnetic measurements. The impact of different homogeneous magnetic field distributions and magnetically perturbed environments is analyzed. Additionally, the effect of the successful biases subtraction on the orientation and the estimated trajectory is detailed. Our results show that the use of magnetic field measurements is beneficial to the correct biases estimation. Further, we show that different magnetic field distributions affect differently the biases estimation process. Moreover, the biases are likewise correctly estimated under perturbed magnetic fields. However, for indoor and urban scenarios the biases estimation process is very slow. PMID:28398232

Adaptable history biases in human perceptual decisions.

PubMed

Abrahamyan, Arman; Silva, Laura Luz; Dakin, Steven C; Carandini, Matteo; Gardner, Justin L

2016-06-21

When making choices under conditions of perceptual uncertainty, past experience can play a vital role. However, it can also lead to biases that worsen decisions. Consistent with previous observations, we found that human choices are influenced by the success or failure of past choices even in a standard two-alternative detection task, where choice history is irrelevant. The typical bias was one that made the subject switch choices after a failure. These choice history biases led to poorer performance and were similar for observers in different countries. They were well captured by a simple logistic regression model that had been previously applied to describe psychophysical performance in mice. Such irrational biases seem at odds with the principles of reinforcement learning, which would predict exquisite adaptability to choice history. We therefore asked whether subjects could adapt their irrational biases following changes in trial order statistics. Adaptability was strong in the direction that confirmed a subject's default biases, but weaker in the opposite direction, so that existing biases could not be eradicated. We conclude that humans can adapt choice history biases, but cannot easily overcome existing biases even if irrational in the current context: adaptation is more sensitive to confirmatory than contradictory statistics.

A Dynamic Bayesian Observer Model Reveals Origins of Bias in Visual Path Integration.

PubMed

Lakshminarasimhan, Kaushik J; Petsalis, Marina; Park, Hyeshin; DeAngelis, Gregory C; Pitkow, Xaq; Angelaki, Dora E

2018-06-20

Path integration is a strategy by which animals track their position by integrating their self-motion velocity. To identify the computational origins of bias in visual path integration, we asked human subjects to navigate in a virtual environment using optic flow and found that they generally traveled beyond the goal location. Such a behavior could stem from leaky integration of unbiased self-motion velocity estimates or from a prior expectation favoring slower speeds that causes velocity underestimation. Testing both alternatives using a probabilistic framework that maximizes expected reward, we found that subjects' biases were better explained by a slow-speed prior than imperfect integration. When subjects integrate paths over long periods, this framework intriguingly predicts a distance-dependent bias reversal due to buildup of uncertainty, which we also confirmed experimentally. These results suggest that visual path integration in noisy environments is limited largely by biases in processing optic flow rather than by leaky integration. Copyright © 2018 Elsevier Inc. All rights reserved.

Scanning of speechless comics changes spatial biases in mental model construction.

PubMed

Román, Antonio; Flumini, Andrea; Santiago, Julio

2018-08-05

The mental representation of both time and number shows lateral spatial biases, which can be affected by habitual reading and writing direction. However, this effect is in place before children begin to read. One potential early cause is the experiences of looking at picture books together with a carer, as those images also follow the directionality of the script. What is the underlying mechanism for this effect? In the present study, we test the possibility that such experiences induce spatial biases in mental model construction, a mechanism which is a good candidate to induce the biases observed with numbers and times. We presented a speechless comic in either standard (left-to-right) or mirror-reversed (right-to-left) form to adult Spanish participants. We then asked them to draw the scene depicted by sentences like 'the square is between the cross and the circle'. The position of the lateral objects in these drawings reveals the spatial biases at work when building mental models in working memory. Under conditions of highly consistent directionality, the mirror comic changed pre-existing lateral biases. Processes of mental model construction in working memory stand as a potential mechanism for the generation of spatial biases for time and number.This article is part of the theme issue 'Varieties of abstract concepts: development, use and representation in the brain'. © 2018 The Author(s).

Attention bias to threat faces in severe mood dysregulation.

PubMed

Hommer, Rebecca E; Meyer, Allison; Stoddard, Joel; Connolly, Megan E; Mogg, Karin; Bradley, Brendan P; Pine, Daniel S; Leibenluft, Ellen; Brotman, Melissa A

2014-07-01

We used a dot-probe paradigm to examine attention bias toward threat (i.e., angry) and happy face stimuli in severe mood dysregulation (SMD) versus healthy comparison (HC) youth. The tendency to allocate attention to threat is well established in anxiety and other disorders of negative affect. SMD is characterized by the negative affect of irritability, and longitudinal studies suggest childhood irritability predicts adult anxiety and depression. Therefore, it is important to study pathophysiologic connections between irritability and anxiety disorders. SMD patients (N = 74) and HC youth (N = 42) completed a visual probe paradigm to assess attention bias to emotional faces. Diagnostic interviews were conducted and measures of irritability and anxiety were obtained in patients. SMD youth differed from HC youth in having a bias toward threatening faces (P < .01). Threat bias was positively correlated with the severity of the SMD syndrome and depressive symptoms; degree of threat bias did not differ between SMD youth with and without co-occurring anxiety disorders or depression. SMD and HC youth did not differ in bias toward or away from happy faces. SMD youth demonstrate an attention bias toward threat, with greater threat bias associated with higher levels of SMD symptom severity. Our findings suggest that irritability may share a pathophysiological link with anxiety and depressive disorders. This finding suggests the value of exploring further whether attention bias modification treatments that are effective for anxiety are also helpful in the treatment of irritability. © 2013 Wiley Periodicals, Inc.

Modifying Threat-Related Interpretive Bias in Adolescents

ERIC Educational Resources Information Center

Salemink, Elske; Wiers, Reinout W.

2011-01-01

Socially anxious feelings sharply increase during adolescence and such feelings have been associated with interpretive biases. Studies in adults have shown that interpretive biases can be modified using Cognitive Bias Modification procedures (CBM-I) and subsequent effects on anxiety have been observed. The current study was designed to examine…

Differences in codon bias cannot explain differences in translational power among microbes.

PubMed

Dethlefsen, Les; Schmidt, Thomas M

2005-01-06

Translational power is the cellular rate of protein synthesis normalized to the biomass invested in translational machinery. Published data suggest a previously unrecognized pattern: translational power is higher among rapidly growing microbes, and lower among slowly growing microbes. One factor known to affect translational power is biased use of synonymous codons. The correlation within an organism between expression level and degree of codon bias among genes of Escherichia coli and other bacteria capable of rapid growth is commonly attributed to selection for high translational power. Conversely, the absence of such a correlation in some slowly growing microbes has been interpreted as the absence of selection for translational power. Because codon bias caused by translational selection varies between rapidly growing and slowly growing microbes, we investigated whether observed differences in translational power among microbes could be explained entirely by differences in the degree of codon bias. Although the data are not available to estimate the effect of codon bias in other species, we developed an empirically-based mathematical model to compare the translation rate of E. coli to the translation rate of a hypothetical strain which differs from E. coli only by lacking codon bias. Our reanalysis of data from the scientific literature suggests that translational power can differ by a factor of 5 or more between E. coli and slowly growing microbial species. Using empirical codon-specific in vivo translation rates for 29 codons, and several scenarios for extrapolating from these data to estimates over all codons, we find that codon bias cannot account for more than a doubling of the translation rate in E. coli, even with unrealistic simplifying assumptions that exaggerate the effect of codon bias. With more realistic assumptions, our best estimate is that codon bias accelerates translation in E. coli by no more than 60% in comparison to microbes with very little

Visual detail about the body modulates tactile localisation biases.

PubMed

Margolis, Aaron N; Longo, Matthew R

2015-02-01

The localisation of tactile stimuli requires the integration of visual and somatosensory inputs within an internal representation of the body surface and is prone to consistent bias. Joints may play a role in segmenting such internal body representations, and may therefore influence tactile localisation biases, although the nature of this influence remains unclear. Here, we investigate the relationship between conceptual knowledge of joint locations and tactile localisation biases on the hand. In one task, participants localised tactile stimuli applied to the dorsum of their hand. A distal localisation bias was observed in all participants, consistent with previous results. We also manipulated the availability of visual information during this task, to determine whether the absence of this information could account for the distal bias observed here and by Mancini et al. (Neuropsychologia 49:1194-1201, 2011). The observed distal bias increased in magnitude when visual information was restricted, without a corresponding decrease in precision. In a separate task, the same participants indicated, from memory, knuckle locations on a silhouette image of their hand. Analogous distal biases were also seen in the knuckle localisation task. The accuracy of conceptual joint knowledge was not correlated with tactile localisation bias magnitude, although a similarity in observed bias direction suggests that both tasks may rely on a common, higher-order body representation. These results also suggest that distortions of conceptual body representation may be more common in healthy individuals than previously thought.

How Negative Social Bias Affects Memory for Faces: An Electrical Neuroimaging Study

PubMed Central

Proverbio, Alice Mado; La Mastra, Francesca; Zani, Alberto

2016-01-01

During social interactions, we make inferences about people’s personal characteristics based on their appearance. These inferences form a potential prejudice that can positively or negatively bias our interaction with them. Not much is known about the effects of negative bias on face perception and the ability to recognize people faces. This ability was investigated by recording event-related potentials (ERPs) from 128 sites in 16 volunteers. In the first session (encoding), they viewed 200 faces associated with a short fictional story that described anecdotal positive or negative characteristics about each person. In the second session (recognition), they underwent an old/new memory test, in which they had to distinguish 100 new faces from the previously shown faces. ERP data relative to the encoding phase showed a larger anterior negativity in response to negatively (vs. positively) biased faces, indicating an additional processing of faces with unpleasant social traits. In the recognition task, ERPs recorded in response to new faces elicited a larger FN400 than to old faces, and to positive than negative faces. Additionally, old faces elicited a larger Old-New parietal response than new faces, in the form of an enlarged late positive (LPC) component. An inverse solution SwLORETA (450–550 ms) indicated that remembering old faces was associated with the activation of right superior frontal gyrus (SFG), left medial temporal gyrus, and right fusiform gyrus. Only negatively connoted faces strongly activated the limbic and parahippocampal areas and the left SFG. A dissociation was found between familiarity (modulated by negative bias) and recollection (distinguishing old from new faces). PMID:27655327

Lack of blinding of outcome assessors in animal model experiments implies risk of observer bias.

PubMed

Bello, Segun; Krogsbøll, Lasse T; Gruber, Jan; Zhao, Zhizhuang J; Fischer, Doris; Hróbjartsson, Asbjørn

2014-09-01

To examine the impact of not blinding outcome assessors on estimates of intervention effects in animal experiments modeling human clinical conditions. We searched PubMed, Biosis, Google Scholar, and HighWire Press and included animal model experiments with both blinded and nonblinded outcome assessors. For each experiment, we calculated the ratio of odds ratios (ROR), that is, the odds ratio (OR) from nonblinded assessments relative to the corresponding OR from blinded assessments. We standardized the ORs according to the experimental hypothesis, such that an ROR <1 indicates that nonblinded assessor exaggerated intervention effect, that is, exaggerated benefit in experiments investigating possible benefit or exaggerated harm in experiments investigating possible harm. We pooled RORs with inverse variance random-effects meta-analysis. We included 10 (2,450 animals) experiments in the main meta-analysis. Outcomes were subjective in most experiments. The pooled ROR was 0.41 (95% confidence interval [CI], 0.20, 0.82; I(2) = 75%; P < 0.001), indicating an average exaggeration of the nonblinded ORs by 59%. The heterogeneity was quantitative and caused by three pesticides experiments with very large observer bias, pooled ROR was 0.20 (95% CI, 0.07, 0.59) in contrast to the pooled ROR in the other seven experiments, 0.82 (95% CI, 0.57, 1.17). Lack of blinding of outcome assessors in animal model experiments with subjective outcomes implies a considerable risk of observer bias. Copyright © 2014 Elsevier Inc. All rights reserved.

Individual differences in emotional processing and autobiographical memory: interoceptive awareness and alexithymia in the fading affect bias.

PubMed

Muir, Kate; Madill, Anna; Brown, Charity

2017-11-01

The capacity to perceive internal bodily states is linked to emotional awareness and effective emotional regulation. We explore individual differences in emotional awareness in relation to the fading affect bias (FAB), which refers to the greater dwindling of unpleasant compared to pleasant emotions in autobiographical memory. We consider interoceptive awareness and alexithymia in relation to the FAB, and private event rehearsal as a mediating process. With increasing interoceptive awareness, there was an enhanced FAB, but with increasing alexithymia, there was a decreased FAB. Further, the effects of interoceptive awareness were partially mediated by private rehearsal of pleasant events. We provide novel evidence that capacity for emotional awareness and thus effective processing is an important factor predictive of the FAB. Moreover, our results imply an important role for maintaining positive affect in the FAB. Our findings offer new insights into the effects of interoception and alexithymia on autobiographical memory, and support concepts of the FAB emerging as a result of adaptive emotional regulation processes.

Interpreting anomalies observed in oxide semiconductor TFTs under negative and positive bias stress

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

Jin, Jong Woo; Nathan, Arokia, E-mail: an299@cam.ac.uk; Barquinha, Pedro

2016-08-15

Oxide semiconductor thin-film transistors can show anomalous behavior under bias stress. Two types of anomalies are discussed in this paper. The first is the shift in threshold voltage (V{sub TH}) in a direction opposite to the applied bias stress, and highly dependent on gate dielectric material. We attribute this to charge trapping/detrapping and charge migration within the gate dielectric. We emphasize the fundamental difference between trapping/detrapping events occurring at the semiconductor/dielectric interface and those occurring at gate/dielectric interface, and show that charge migration is essential to explain the first anomaly. We model charge migration in terms of the non-instantaneous polarizationmore » density. The second type of anomaly is negative V{sub TH} shift under high positive bias stress, with logarithmic evolution in time. This can be argued as electron-donating reactions involving H{sub 2}O molecules or derived species, with a reaction rate exponentially accelerated by positive gate bias and exponentially decreased by the number of reactions already occurred.« less

Implications of weight-based stigma and self-bias on quality of life among individuals with Schizophrenia

PubMed Central

Barber, Jessica; Palmese, Laura; Reutenauer, Erin L.; Grilo, Carlos; Tek, Cenk

2011-01-01

Obesity has been associated with significant stigma and weight-related self-bias in community and clinical studies, but these issues have not been studied among individuals with schizophrenia. A consecutive series of 70 obese individuals with schizophrenia or schizoaffective disorder underwent assessment for perceptions of weight-based stigmatization, self-directed weight-bias, negative affect, medication compliance, and quality of life. Levels of weight-based stigmatization and self-bias were compared to levels reported for non-psychiatric overweight/obese samples. Weight measures were unrelated to stigma, self-bias, affect, and quality of life. Weight-based stigmatization was lower than published levels for non-psychiatric samples, whereas levels of weight-based self-bias did not differ. After controlling for negative affect, weight-based self-bias predicted an additional 11% of the variance in the quality of life measure. Individuals with schizophrenia and schizoaffective disorder reported weight-based self-bias to the same extent as non-psychiatric samples despite reporting less weight stigma. Weight-based self-bias was associated with poorer quality of life after controlling for negative affect. PMID:21716053

The association between male-biased sex ratio and indicators of stress in red-spotted newts.

PubMed

Aspbury, Andrea S; Grayson, Kristine L; Fantaye, Selamawit; Nichols, Ian; Myers-Burton, Miranda; Ortiz-Mangual, Xavier; Gabor, Caitlin R

2017-05-01

In populations with a male-biased operational sex ratio, coercive mating by males can have fitness consequences for females. One component of reduced fitness for females in populations with a male-biased OSR may be greater activation of the stress response, resulting in higher corticosterone release rates (CORT; a glucocorticoid stress hormone in amphibians). We test the hypothesis that a male-biased sex ratio affects female activity and release rates of CORT and testosterone (T) in male and female red-spotted newts (Notophthalmus viridescens). First, we evaluated if chemical cues from a male-biased sex ratio affect activity and CORT release rates in females. We predicted that females exposed to chemical cues of three males would be less active and have higher CORT release rates than those exposed to chemical cues of one male. Second, we measured CORT release rates of red-spotted newts in field enclosures with either a male-biased or a female-biased sex ratio. We predicted that females in the male-biased treatment would have higher CORT and T release rates than those in a female-biased treatment, owing to higher levels of male harassment. We also predicted that males would have higher CORT and T release rates in male-biased treatments due to higher levels of male-male competition. Females were not less active in response to chemical cues from more males over fewer males, but there was a positive relationship between female activity and CORT when they were exposed to the cues of three males. We also found that females, but not males, in the male-biased sex ratio treatment had higher CORT and T release rates than those in the female-biased treatment. Our results support the hypothesis that a male-biased sex ratio leads to a higher stress response, which may underlie the observed decrease in immune function and body condition in previous work exposing female red-spotted newts to a male-biased sex ratio. This study furthers our understanding of the mechanistic basis

Treatment of Star Catalog Biases in Asteroid Astrometric Observations

DTIC Science & Technology

2010-01-01

90 to +40 (Zacharias et al., 2004). (Note: The recently introduced UCAC3 catalog (Zacharias et al., 2004) covers the entire sky, thus resolving ...the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the...Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 With the catalog biases resolved , a future paper will describe the subsequent development of a

Anchoring bias in online voting

NASA Astrophysics Data System (ADS)

Yang, Zimo; Zhang, Zi-Ke; Zhou, Tao

2012-12-01

Voting online with explicit ratings could largely reflect people's preferences and objects' qualities, but ratings are always irrational, because they may be affected by many unpredictable factors like mood, weather and other people's votes. By analyzing two real systems, this paper reveals a systematic bias embedding in the individual decision-making processes, namely people tend to give a low rating after a low rating, as well as a high rating following a high rating. This so-called anchoring bias is validated via extensive comparisons with null models, and numerically speaking, the extent of bias decays with voting interval in a logarithmic form. Our findings could be applied in the design of recommender systems and considered as important complementary materials to previous knowledge about anchoring effects on financial trades, performance judgments, auctions, and so on.

Immortal time bias in pharmaco-epidemiology.

PubMed

Suissa, Samy

2008-02-15

Immortal time is a span of cohort follow-up during which, because of exposure definition, the outcome under study could not occur. Bias from immortal time was first identified in the 1970s in epidemiology in the context of cohort studies of the survival benefit of heart transplantation. It recently resurfaced in pharmaco-epidemiology, with several observational studies reporting that various medications can be extremely effective at reducing morbidity and mortality. These studies, while using different cohort designs, all involved some form of immortal time and the corresponding bias. In this paper, the author describes various cohort study designs leading to this bias, quantifies its magnitude under different survival distributions, and illustrates it by using data from a cohort of lung cancer patients. The author shows that for time-based, event-based, and exposure-based cohort definitions, the bias in the rate ratio resulting from misclassified or excluded immortal time increases proportionately to the duration of immortal time. The bias is more pronounced with a decreasing hazard function for the outcome event, as illustrated with the Weibull distribution compared with a constant hazard from the exponential distribution. In conclusion, observational studies of drug benefit in which computerized databases are used must be designed and analyzed properly to avoid immortal time bias.

A principal components analysis of dynamic spatial memory biases.

PubMed

Motes, Michael A; Hubbard, Timothy L; Courtney, Jon R; Rypma, Bart

2008-09-01

Research has shown that spatial memory for moving targets is often biased in the direction of implied momentum and implied gravity, suggesting that representations of the subjective experiences of these physical principles contribute to such biases. The present study examined the association between these spatial memory biases. Observers viewed targets that moved horizontally from left to right before disappearing or viewed briefly shown stationary targets. After a target disappeared, observers indicated the vanishing position of the target. Principal components analysis revealed that biases along the horizontal axis of motion loaded on separate components from biases along the vertical axis orthogonal to motion. The findings support the hypothesis that implied momentum and implied gravity biases have unique influences on spatial memory. (c) 2008 APA, all rights reserved.

Biases in research: risk factors for non-replicability in psychotherapy and pharmacotherapy research.

PubMed

Leichsenring, F; Abbass, A; Hilsenroth, M J; Leweke, F; Luyten, P; Keefe, J R; Midgley, N; Rabung, S; Salzer, S; Steinert, C

2017-04-01

Replicability of findings is an essential prerequisite of research. For both basic and clinical research, however, low replicability of findings has recently been reported. Replicability may be affected by research biases not sufficiently controlled for by the existing research standards. Several biases such as researcher allegiance or selective reporting are well-known for affecting results. For psychotherapy and pharmacotherapy research, specific additional biases may affect outcome (e.g. therapist allegiance, therapist effects or impairments in treatment implementation). For meta-analyses further specific biases are relevant. In psychotherapy and pharmacotherapy research these biases have not yet been systematically discussed in the context of replicability. Using a list of 13 biases as a starting point, we discuss each bias's impact on replicability. We illustrate each bias by selective findings of recent research, showing that (1) several biases are not yet sufficiently controlled for by the presently applied research standards, (2) these biases have a pernicious effect on replicability of findings. For the sake of research credibility, it is critical to avoid these biases in future research. To control for biases and to improve replicability, we propose to systematically implement several measures in psychotherapy and pharmacotherapy research, such as adversarial collaboration (inviting academic rivals to collaborate), reviewing study design prior to knowing the results, triple-blind data analysis (including subjects, investigators and data managers/statisticians), data analysis by other research teams (crowdsourcing), and, last not least, updating reporting standards such as CONSORT or the Template for Intervention Description and Replication (TIDieR).

Quantifying the clear-sky bias of satellite-derived infrared LST

NASA Astrophysics Data System (ADS)

Ermida, S. L.; Trigo, I. F.; DaCamara, C.

2017-12-01

Land surface temperature (LST) is one of the most relevant parameters when addressing the physical processes that take place at the surface of the Earth. Satellite data are particularly appropriate for measuring LST over the globe with high temporal resolution. Remote-sensed LST estimation from space-borne sensors has been systematically performed over the Globe for nearly 3 decades and geostationary LST climate data records are now available. The retrieval of LST from satellite observations generally relies on measurements in the thermal infrared (IR) window. Although there is a large number of IR sensors on-board geostationary satellites and polar orbiters suitable for LST retrievals with different temporal and spatial resolutions, the use of IR observations limits LST estimates to clear sky conditions. As a consequence, climate studies based on IR LST are likely to be affected by the restriction of LST data to cloudless conditions. However, such "clear sky bias" has never been quantified and, therefore, the actual impact of relying only on clear sky data is still to be determined. On the other hand, an "all-weather" global LST database may be set up based on passive microwave (MW) measurements which are much less affected by clouds. An 8-year record of all-weather MW LST is here used to quantify the clear-sky bias of IR LST at global scale based on MW observations performed by the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) onboard NASA's Aqua satellite. Selection of clear-sky and cloudy pixels is based on information derived from measurements performed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the same satellite.

Bias in Hazard Ratios Arising From Misclassification According to Self-Reported Weight and Height in Observational Studies of Body Mass Index and Mortality.

PubMed

Flegal, Katherine M; Kit, Brian K; Graubard, Barry I

2018-01-01

Misclassification of body mass index (BMI) categories arising from self-reported weight and height can bias hazard ratios in studies of BMI and mortality. We examined the effects on hazard ratios of such misclassification using national US survey data for 1976 through 2010 that had both measured and self-reported weight and height along with mortality follow-up for 48,763 adults and a subset of 17,405 healthy never-smokers. BMI was categorized as <22.5 (low), 22.5-24.9 (referent), 25.0-29.9 (overweight), 30.0-34.9 (class I obesity), and ≥35.0 (class II-III obesity). Misreporting at higher BMI categories tended to bias hazard ratios upwards for those categories, but that effect was augmented, counterbalanced, or even reversed by misreporting in other BMI categories, in particular those that affected the reference category. For example, among healthy male never-smokers, misclassifications affecting the overweight and the reference categories changed the hazard ratio for overweight from 0.85 with measured data to 1.24 with self-reported data. Both the magnitude and direction of bias varied according to the underlying hazard ratios in measured data, showing that findings on bias from one study should not be extrapolated to a study with different underlying hazard ratios. Because of misclassification effects, self-reported weight and height cannot reliably indicate the lowest-risk BMI category. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Attentional bias mediates the effect of neurostimulation on emotional vulnerability.

PubMed

Chen, Nigel T M; Basanovic, Julian; Notebaert, Lies; MacLeod, Colin; Clarke, Patrick J F

2017-10-01

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique which has garnered recent interest in the potential treatment for emotion-based psychopathology. While accumulating evidence suggests that tDCS may attenuate emotional vulnerability, critically, little is known about underlying mechanisms of this effect. The present study sought to clarify this by examining the possibility that tDCS may affect emotional vulnerability via its capacity to modulate attentional bias towards threatening information. Fifty healthy participants were randomly assigned to receive either anodal tDCS (2 mA/min) stimulation to the left dorsolateral prefrontal cortex (DLPFC), or sham. Participants were then eye tracked during a dual-video stressor task designed to elicit emotional reactivity, while providing a concurrent in-vivo measure of attentional bias. Greater attentional bias towards threatening information was associated with greater emotional reactivity to the stressor task. Furthermore, the active tDCS group showed reduced attentional bias to threat, compared to the sham group. Importantly, attentional bias was found to statistically mediate the effect of tDCS on emotional reactivity, while no direct effect of tDCS on emotional reactivity was observed. The findings are consistent with the notion that the effect of tDCS on emotional vulnerability may be mediated by changes in attentional bias, holding implications for the application of tDCS in emotion-based psychopathology. The findings also highlight the utility of in-vivo eye tracking measures in the examination of the mechanisms associated with DLPFC neuromodulation in emotional vulnerability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Projecting my envy onto you: neurocognitive mechanisms of an offline emotional egocentricity bias.

PubMed

Steinbeis, Nikolaus; Singer, Tania

2014-11-15

Humans often project their own beliefs, desires and emotions onto others, indicating an inherent egocentrism. In five studies we investigated the neurocognitive mechanisms underlying emotional egocentricity bias (EEB) and specifically an offline EEB, defined as the projection of one's own tendency to react with a certain emotional response pattern in a given situation onto other people. We used a competitive reaction time game associated with monetary gains and losses that allowed inducing feelings of envy and Schadenfreude. While we found evidence for the first hand experience of envy and Schadenfreude, we also observed an offline bias, that is participants on average projected feelings of envy and Schadenfreude when having to judge others. Importantly the extent of experienced and projected social emotions were highly correlated. This bias was observed when participants were both directly involved and also as an uninvolved party, suggesting the offline bias to be independent of the presently experienced emotion. Under increased time pressure however an online bias emerged whereby participants just projected their presently experienced emotions onto the other. Finally, we show that on the neural level shared neuronal networks underlie the offline EEB at least for envy. Thus, for envy, activity of the same part of anterior insula was sensitive to individual differences both in the experience and the projection of envy. These findings outline the set of circumstances leading to specific types of empathic attribution biases and show that individual differences in the experience of social emotions are predictive of the offline egocentricity bias both on a behavioral as well as a neural level. These data extend present models on the neurocognitive mechanisms of interpersonal understanding in the socio-affective domain. Copyright © 2014 Elsevier Inc. All rights reserved.

Space-based bias of covert visual attention in complex regional pain syndrome.

PubMed

Bultitude, Janet H; Walker, Ian; Spence, Charles

2017-09-01

See Legrain (doi:10.1093/awx188) for a scientific commentary on this article. Some patients with complex regional pain syndrome report that movements of the affected limb are slow, more effortful, and lack automaticity. These symptoms have been likened to the syndrome that sometimes follows brain injury called hemispatial neglect, in which patients exhibit attentional impairments and problems with movements affecting the contralesional side of the body and space. Psychophysical testing of patients with complex regional pain syndrome has found evidence for spatial biases when judging visual targets distanced at 2 m, but not in directions that indicate reduced attention to the affected side. In contrast, when judging visual or tactile stimuli presented on their own body surface, or pictures of hands and feet within arm's reach, patients with complex regional pain syndrome exhibited a bias away from the affected side. What is not yet known is whether patients with complex regional pain syndrome only have biased attention for bodily-specific information in the space within arm's reach, or whether they also show a bias for information that is not associated with the body, suggesting a more generalized attention deficit. Using a temporal order judgement task, we found that patients with complex regional pain syndrome processed visual stimuli more slowly on the affected side (relative to the unaffected side) when the lights were projected onto a blank surface (i.e. when no bodily information was visible), and when the lights were projected onto the dorsal surfaces of their uncrossed hands. However, with the arms crossed (such that the left and right lights projected onto the right and left hands, respectively), patients' responses were no different than controls. These results provide the first demonstration of a generalized attention bias away from the affected side of space in complex regional pain syndrome patients that is not specifically related to bodily

Opposing Forces of A/T-Biased Mutations and G/C-Biased Gene Conversions Shape the Genome of the Nematode Pristionchus pacificus

PubMed Central

Weller, Andreas M.; Rödelsperger, Christian; Eberhardt, Gabi; Molnar, Ruxandra I.; Sommer, Ralf J.

2014-01-01

Base substitution mutations are a major source of genetic novelty and mutation accumulation line (MAL) studies revealed a nearly universal AT bias in de novo mutation spectra. While a comparison of de novo mutation spectra with the actual nucleotide composition in the genome suggests the existence of general counterbalancing mechanisms, little is known about the evolutionary and historical details of these opposing forces. Here, we correlate MAL-derived mutation spectra with patterns observed from population resequencing. Variation observed in natural populations has already been subject to evolutionary forces. Distinction between rare and common alleles, the latter of which are close to fixation and of presumably older age, can provide insight into mutational processes and their influence on genome evolution. We provide a genome-wide analysis of de novo mutations in 22 MALs of the nematode Pristionchus pacificus and compare the spectra with natural variants observed in resequencing of 104 natural isolates. MALs show an AT bias of 5.3, one of the highest values observed to date. In contrast, the AT bias in natural variants is much lower. Specifically, rare derived alleles show an AT bias of 2.4, whereas common derived alleles close to fixation show no AT bias at all. These results indicate the existence of a strong opposing force and they suggest that the GC content of the P. pacificus genome is in equilibrium. We discuss GC-biased gene conversion as a potential mechanism acting against AT-biased mutations. This study provides insight into genome evolution by combining MAL studies with natural variation. PMID:24414549

A mathematical model of case-ascertainment bias: Applied to case-control studies nested within a randomized screening trial.

PubMed

Jansen, Rick J; Alexander, Bruce H; Hayes, Richard B; Miller, Anthony B; Wacholder, Sholom; Church, Timothy R

2018-01-01

When some individuals are screen-detected before the beginning of the study, but otherwise would have been diagnosed symptomatically during the study, this results in different case-ascertainment probabilities among screened and unscreened participants, referred to here as lead-time-biased case-ascertainment (LTBCA). In fact, this issue can arise even in risk-factor studies nested within a randomized screening trial; even though the screening intervention is randomly allocated to trial arms, there is no randomization to potential risk-factors and uptake of screening can differ by risk-factor strata. Under the assumptions that neither screening nor the risk factor affects underlying incidence and no other forms of bias operate, we simulate and compare the underlying cumulative incidence and that observed in the study due to LTBCA. The example used will be constructed from the randomized Prostate, Lung, Colorectal, and Ovarian cancer screening trial. The derived mathematical model is applied to simulating two nested studies to evaluate the potential for screening bias in observational lung cancer studies. Because of differential screening under plausible assumptions about preclinical incidence and duration, the simulations presented here show that LTBCA due to chest x-ray screening can significantly increase the estimated risk of lung cancer due to smoking by 1% and 50%. Traditional adjustment methods cannot account for this bias, as the influence screening has on observational study estimates involves events outside of the study observation window (enrollment and follow-up) that change eligibility for potential participants, thus biasing case ascertainment.

Rapid Evolution of Ovarian-Biased Genes in the Yellow Fever Mosquito (Aedes aegypti).

PubMed

Whittle, Carrie A; Extavour, Cassandra G

2017-08-01

Males and females exhibit highly dimorphic phenotypes, particularly in their gonads, which is believed to be driven largely by differential gene expression. Typically, the protein sequences of genes upregulated in males, or male-biased genes, evolve rapidly as compared to female-biased and unbiased genes. To date, the specific study of gonad-biased genes remains uncommon in metazoans. Here, we identified and studied a total of 2927, 2013, and 4449 coding sequences (CDS) with ovary-biased, testis-biased, and unbiased expression, respectively, in the yellow fever mosquito Aedes aegypti The results showed that ovary-biased and unbiased CDS had higher nonsynonymous to synonymous substitution rates (dN/dS) and lower optimal codon usage (those codons that promote efficient translation) than testis-biased genes. Further, we observed higher dN/dS in ovary-biased genes than in testis-biased genes, even for genes coexpressed in nonsexual (embryo) tissues. Ovary-specific genes evolved exceptionally fast, as compared to testis- or embryo-specific genes, and exhibited higher frequency of positive selection. Genes with ovary expression were preferentially involved in olfactory binding and reception. We hypothesize that at least two potential mechanisms could explain rapid evolution of ovary-biased genes in this mosquito: (1) the evolutionary rate of ovary-biased genes may be accelerated by sexual selection (including female-female competition or male-mate choice) affecting olfactory genes during female swarming by males, and/or by adaptive evolution of olfactory signaling within the female reproductive system ( e.g. , sperm-ovary signaling); and/or (2) testis-biased genes may exhibit decelerated evolutionary rates due to the formation of mating plugs in the female after copulation, which limits male-male sperm competition. Copyright © 2017 by the Genetics Society of America.

Observational selection biases in time-delay strong lensing and their impact on cosmography

NASA Astrophysics Data System (ADS)

Collett, Thomas E.; Cunnington, Steven D.

2016-11-01

Inferring cosmological parameters from time-delay strong lenses requires a significant investment of telescope time; it is therefore tempting to focus on the systems with the brightest sources, the highest image multiplicities and the widest image separations. We investigate if this selection bias can influence the properties of the lenses studied and the cosmological parameters inferred. Using an ellipsoidal power-law deflector population, we build a sample of double- and quadruple-image systems. Assuming reasonable thresholds on image separation and flux, based on current lens monitoring campaigns, we find that the typical density profile slopes of monitorable lenses are significantly shallower than the input ensemble. From a sample of quads, we find that this selection function can introduce a 3.5 per cent bias on the inferred time-delay distances if the properties of the input ensemble are (incorrectly) used as priors on the lens model. This bias remains at the 2.4 per cent level when high-resolution imaging of the quasar host is used to precisely infer the properties of individual lenses. We also investigate if the lines of sight for monitorable strong lenses are biased. The expectation value for the line-of-sight convergence is increased by 0.009 (0.004) for quads (doubles) implying a 0.9 per cent (0.4 per cent) bias on H0. We therefore conclude that whilst the properties of typical quasar lenses and their lines of sight do deviate from the global population, the total magnitude of this effect is likely to be a subdominant effect for current analyses, but has the potential to be a major systematic for samples of ˜25 or more lenses.

Cognitive Bias in the Verification and Validation of Space Flight Systems

NASA Technical Reports Server (NTRS)

Larson, Steve

2012-01-01

Cognitive bias is generally recognized as playing a significant role in virtually all domains of human decision making. Insight into this role is informally built into many of the system engineering practices employed in the aerospace industry. The review process, for example, typically has features that help to counteract the effect of bias. This paper presents a discussion of how commonly recognized biases may affect the verification and validation process. Verifying and validating a system is arguably more challenging than development, both technically and cognitively. Whereas there may be a relatively limited number of options available for the design of a particular aspect of a system, there is a virtually unlimited number of potential verification scenarios that may be explored. The probability of any particular scenario occurring in operations is typically very difficult to estimate, which increases reliance on judgment that may be affected by bias. Implementing a verification activity often presents technical challenges that, if they can be overcome at all, often result in a departure from actual flight conditions (e.g., 1-g testing, simulation, time compression, artificial fault injection) that may raise additional questions about the meaningfulness of the results, and create opportunities for the introduction of additional biases. In addition to mitigating the biases it can introduce directly, the verification and validation process must also overcome the cumulative effect of biases introduced during all previous stages of development. A variety of cognitive biases will be described, with research results for illustration. A handful of case studies will be presented that show how cognitive bias may have affected the verification and validation process on recent JPL flight projects, identify areas of strength and weakness, and identify potential changes or additions to commonly used techniques that could provide a more robust verification and validation of

An online means of testing asymmetries in seating preference reveals a bias for airplanes and theaters.

PubMed

Nicholls, Michael E R; Thomas, Nicole A; Loetscher, Tobias

2013-08-01

The aim of this study was to investigate asymmetrical interactions between humans and their environment using online seat booking sites. Functional differences between the cerebral hemispheres affect the choices people make. For example, when asked to imagine going to a cinema, people preferentially select seats to the right We investigated whether this experimental research generalizes to online booking sites for aircraft and theaters. Occupancy rates for seats taken on the left and right sides were assessed for 100 airline flights with 12,762 available seats and 37 theater performances with 34,456 seats. On the basis of previous research, a rightward bias was predicted for aircraft and theaters. For aircraft, contrary to expectation, occupancy rate was higher for left- compared with right-side seats. For theaters, a rightward bias was observed when the theater was less than half full.The bias was not affected by the orientation of the map. For aircraft, the leftward preference could be attributable to a rightward turning bias or a "feeling" that the port seats are closer to the exit, even though they are not. For theaters, the data demonstrate that the rightward preference observed in earlier studies exists only when the theater is relatively empty. Asymmetrical seating may play an important role in the efficient assimilation of information from the environment, and this role should take this into account when designing effective human-environment interfaces.The online method of assessing seating used in the current study provides an informative and potentially powerful means of assessing asymmetries in human perception and action.

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…

The cross-cut statistic and its sensitivity to bias in observational studies with ordered doses of treatment.

PubMed

Rosenbaum, Paul R

2016-03-01

A common practice with ordered doses of treatment and ordered responses, perhaps recorded in a contingency table with ordered rows and columns, is to cut or remove a cross from the table, leaving the outer corners--that is, the high-versus-low dose, high-versus-low response corners--and from these corners to compute a risk or odds ratio. This little remarked but common practice seems to be motivated by the oldest and most familiar method of sensitivity analysis in observational studies, proposed by Cornfield et al. (1959), which says that to explain a population risk ratio purely as bias from an unobserved binary covariate, the prevalence ratio of the covariate must exceed the risk ratio. Quite often, the largest risk ratio, hence the one least sensitive to bias by this standard, is derived from the corners of the ordered table with the central cross removed. Obviously, the corners use only a portion of the data, so a focus on the corners has consequences for the standard error as well as for bias, but sampling variability was not a consideration in this early and familiar form of sensitivity analysis, where point estimates replaced population parameters. Here, this cross-cut analysis is examined with the aid of design sensitivity and the power of a sensitivity analysis. © 2015, The International Biometric Society.

Biased perception about gene technology: How perceived naturalness and affect distort benefit perception.

PubMed

Siegrist, Michael; Hartmann, Christina; Sütterlin, Bernadette

2016-01-01

In two experiments, the participants showed biased responses when asked to evaluate the benefits of gene technology. They evaluated the importance of additional yields in corn fields due to a newly introduced variety, which would increase a farmer's revenues. In one condition, the newly introduced variety was described as a product of traditional breeding; in the other, it was identified as genetically modified (GM). The two experiments' findings showed that the same benefits were perceived as less important for a farmer when these were the result of GM crops compared with traditionally bred crops. Mediation analyses suggest that perceived naturalness and the affect associated with the technology per se influence the interpretation of the new information. The lack of perceived naturalness of gene technology seems to be the reason for the participants' perceived lower benefits of a new corn variety in the gene technology condition compared with the perceptions of the participants assigned to the traditional breeding condition. The strategy to increase the acceptance of gene technology by introducing plant varieties that better address consumer and producer needs may not work because people discount its associated benefits. Copyright © 2015 Elsevier Ltd. All rights reserved.

Motion, identity and the bias toward agency

PubMed Central

Fields, Chris

2014-01-01

The well-documented human bias toward agency as a cause and therefore an explanation of observed events is typically attributed to evolutionary selection for a “social brain”. Based on a review of developmental and adult behavioral and neurocognitive data, it is argued that the bias toward agency is a result of the default human solution, developed during infancy, to the computational requirements of object re-identification over gaps in observation of more than a few seconds. If this model is correct, overriding the bias toward agency to construct mechanistic explanations of observed events requires structure-mapping inferences, implemented by the pre-motor action planning system, that replace agents with mechanisms as causes of unobserved changes in contextual or featural properties of objects. Experiments that would test this model are discussed. PMID:25191245

Propranolol reduces implicit negative racial bias.

PubMed

Terbeck, Sylvia; Kahane, Guy; McTavish, Sarah; Savulescu, Julian; Cowen, Philip J; Hewstone, Miles

2012-08-01

Implicit negative attitudes towards other races are important in certain kinds of prejudicial social behaviour. Emotional mechanisms are thought to be involved in mediating implicit "outgroup" bias but there is little evidence concerning the underlying neurobiology. The aim of the present study was to examine the role of noradrenergic mechanisms in the generation of implicit racial attitudes. Healthy volunteers (n = 36) of white ethnic origin, received a single oral dose of the β-adrenoceptor antagonist, propranolol (40 mg), in a randomised, double-blind, parallel group, placebo-controlled, design. Participants completed an explicit measure of prejudice and the racial implicit association test (IAT), 1-2 h after propranolol administration. Relative to placebo, propranolol significantly lowered heart rate and abolished implicit racial bias, without affecting the measure of explicit racial prejudice. Propranolol did not affect subjective mood. Our results indicate that β-adrenoceptors play a role in the expression of implicit racial attitudes suggesting that noradrenaline-related emotional mechanisms may mediate negative racial bias. Our findings may also have practical importance given that propranolol is a widely used drug. However, further studies will be needed to examine whether a similar effect can be demonstrated in the course of clinical treatment.

Adolescent recognition of parental affect: influence of depressive symptoms.

PubMed

Ehrmantrout, Nikki; Allen, Nicholas B; Leve, Craig; Davis, Betsy; Sheeber, Lisa

2011-08-01

This study examined depressive biases in adolescents' labeling of parental affect. Adolescents (151 girls; 82 boys) and their parents engaged in videotaped problem-solving interactions. Adolescents then participated in a video-mediated recall procedure in which they watched the videotaped interaction and indicated how they thought their parents were feeling. Indices of parents' affect during the problem-solving interactions were also provided by parent self-report and behavioral observations. Adolescent depressive symptoms were associated with overreporting of parental aggressive affect and underreporting of parental happy and neutral affects, relative to both directly observed and self-reported parental affect. Depressive symptoms were not associated with overreporting of parental dysphoric affect. Given the importance of accurately reading affective cues for negotiating interpersonal interactions, these findings likely have implications for understanding processes that contribute to adverse relationships among the families of adolescents with depressive symptoms. © 2011 American Psychological Association

Plant Disease Severity Assessment-How Rater Bias, Assessment Method, and Experimental Design Affect Hypothesis Testing and Resource Use Efficiency.

PubMed

Chiang, Kuo-Szu; Bock, Clive H; Lee, I-Hsuan; El Jarroudi, Moussa; Delfosse, Philippe

2016-12-01

The effect of rater bias and assessment method on hypothesis testing was studied for representative experimental designs for plant disease assessment using balanced and unbalanced data sets. Data sets with the same number of replicate estimates for each of two treatments are termed "balanced" and those with unequal numbers of replicate estimates are termed "unbalanced". The three assessment methods considered were nearest percent estimates (NPEs), an amended 10% incremental scale, and the Horsfall-Barratt (H-B) scale. Estimates of severity of Septoria leaf blotch on leaves of winter wheat were used to develop distributions for a simulation model. The experimental designs are presented here in the context of simulation experiments which consider the optimal design for the number of specimens (individual units sampled) and the number of replicate estimates per specimen for a fixed total number of observations (total sample size for the treatments being compared). The criterion used to gauge each method was the power of the hypothesis test. As expected, at a given fixed number of observations, the balanced experimental designs invariably resulted in a higher power compared with the unbalanced designs at different disease severity means, mean differences, and variances. Based on these results, with unbiased estimates using NPE, the recommended number of replicate estimates taken per specimen is 2 (from a sample of specimens of at least 30), because this conserves resources. Furthermore, for biased estimates, an apparent difference in the power of the hypothesis test was observed between assessment methods and between experimental designs. Results indicated that, regardless of experimental design or rater bias, an amended 10% incremental scale has slightly less power compared with NPEs, and that the H-B scale is more likely than the others to cause a type II error. These results suggest that choice of assessment method, optimizing sample number and number of replicate

Temperature effects on pitfall catches of epigeal arthropods: a model and method for bias correction.

PubMed

Saska, Pavel; van der Werf, Wopke; Hemerik, Lia; Luff, Martin L; Hatten, Timothy D; Honek, Alois; Pocock, Michael

2013-02-01

Carabids and other epigeal arthropods make important contributions to biodiversity, food webs and biocontrol of invertebrate pests and weeds. Pitfall trapping is widely used for sampling carabid populations, but this technique yields biased estimates of abundance ('activity-density') because individual activity - which is affected by climatic factors - affects the rate of catch. To date, the impact of temperature on pitfall catches, while suspected to be large, has not been quantified, and no method is available to account for it. This lack of knowledge and the unavailability of a method for bias correction affect the confidence that can be placed on results of ecological field studies based on pitfall data.Here, we develop a simple model for the effect of temperature, assuming a constant proportional change in the rate of catch per °C change in temperature, r , consistent with an exponential Q 10 response to temperature. We fit this model to 38 time series of pitfall catches and accompanying temperature records from the literature, using first differences and other detrending methods to account for seasonality. We use meta-analysis to assess consistency of the estimated parameter r among studies.The mean rate of increase in total catch across data sets was 0·0863 ± 0·0058 per °C of maximum temperature and 0·0497 ± 0·0107 per °C of minimum temperature. Multiple regression analyses of 19 data sets showed that temperature is the key climatic variable affecting total catch. Relationships between temperature and catch were also identified at species level. Correction for temperature bias had substantial effects on seasonal trends of carabid catches. Synthesis and Applications . The effect of temperature on pitfall catches is shown here to be substantial and worthy of consideration when interpreting results of pitfall trapping. The exponential model can be used both for effect estimation and for bias correction of observed data. Correcting for temperature

Effects of Bias Modification Training in Binge Eating Disorder.

PubMed

Schmitz, Florian; Svaldi, Jennifer

2017-09-01

Food-related attentional biases have been identified as maintaining factors in binge eating disorder (BED) as they can trigger a binge episode. Bias modification training may reduce symptoms, as it has been shown to be successful in other appetitive disorders. The aim of this study was to assess and modify food-related biases in BED. It was tested whether biases could be increased and decreased by means of a modified dot-probe paradigm, how long such bias modification persisted, and whether this affected subjective food craving. Participants were randomly assigned to a bias enhancement (attend to food stimulus) group or to a bias reduction (avoid food stimulus) group. Food-related attentional bias was found to be successfully reduced in the bias-reduction group, and effects persisted briefly. Additionally, subjective craving for food was influenced by the intervention, and possible mechanisms are discussed. Given these promising initial results, future research should investigate boundary conditions of the experimental intervention to understand how it could complement treatment of BED. Copyright © 2017. Published by Elsevier Ltd.

Toward a synthesis of cognitive biases: how noisy information processing can bias human decision making.

PubMed

Hilbert, Martin

2012-03-01

A single coherent framework is proposed to synthesize long-standing research on 8 seemingly unrelated cognitive decision-making biases. During the past 6 decades, hundreds of empirical studies have resulted in a variety of rules of thumb that specify how humans systematically deviate from what is normatively expected from their decisions. Several complementary generative mechanisms have been proposed to explain those cognitive biases. Here it is suggested that (at least) 8 of these empirically detected decision-making biases can be produced by simply assuming noisy deviations in the memory-based information processes that convert objective evidence (observations) into subjective estimates (decisions). An integrative framework is presented to show how similar noise-based mechanisms can lead to conservatism, the Bayesian likelihood bias, illusory correlations, biased self-other placement, subadditivity, exaggerated expectation, the confidence bias, and the hard-easy effect. Analytical tools from information theory are used to explore the nature and limitations that characterize such information processes for binary and multiary decision-making exercises. The ensuing synthesis offers formal mathematical definitions of the biases and their underlying generative mechanism, which permits a consolidated analysis of how they are related. This synthesis contributes to the larger goal of creating a coherent picture that explains the relations among the myriad of seemingly unrelated biases and their potential psychological generative mechanisms. Limitations and research questions are discussed.

Partial Sleep Deprivation Attenuates the Positive Affective System: Effects Across Multiple Measurement Modalities.

PubMed

Finan, Patrick H; Quartana, Phillip J; Remeniuk, Bethany; Garland, Eric L; Rhudy, Jamie L; Hand, Matthew; Irwin, Michael R; Smith, Michael T

2017-01-01

Ample behavioral and neurobiological evidence links sleep and affective functioning. Recent self-report evidence suggests that the affective problems associated with sleep loss may be stronger for positive versus negative affective state and that those effects may be mediated by changes in electroencepholographically measured slow wave sleep (SWS). In the present study, we extend those preliminary findings using multiple measures of affective functioning. In a within-subject randomized crossover experiment, we tested the effects of one night of sleep continuity disruption via forced awakenings (FA) compared to one night of uninterrupted sleep (US) on three measures of positive and negative affective functioning: self-reported affective state, affective pain modulation, and affect-biased attention. The study was set in an inpatient clinical research suite. Healthy, good sleeping adults (N = 45) were included. Results indicated that a single night of sleep continuity disruption attenuated positive affective state via FA-induced reductions in SWS. Additionally, sleep continuity disruption attenuated the inhibition of pain by positive affect as well as attention bias to positive affective stimuli. Negative affective state, negative affective pain facilitation, nor negative attention bias were altered by sleep continuity disruption. The present findings, observed across multiple measures of affective function, suggest that sleep continuity disruption has a stronger influence on the positive affective system relative to the negative affective affective system. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

W(h)ither the Oracle? Cognitive biases and other human challenges of integrated environmental modeling

USGS Publications Warehouse

Glynn, Pierre D.; Ames, D.P.; Quinn, N. W. T.; Rizzoli, A.E.

2014-01-01

Integrated environmental modeling (IEM) can organize and increase our knowledge of the complex, dynamic ecosystems that house our natural resources and control the quality of our environments. Human behavior, however, must be taken into account. Human biases/heuristics reflect adaptation over our evolutionary past to frequently experienced situations that affected our survival and that provided sharply distinguished feedbacks at the level of the individual. Unfortunately, human behavior is not adapted to the more diffusely experienced, less frequently encountered, problems and issues that IEM typically seeks to address in the simulation of natural resources and environments. While seeking inspiration from the prophetic traditions of the Oracle of Delphi, several human biases are identified that may affect how the science base of IEM is assembled, and how IEM results are interpreted and used. These biases are supported by personal observations, and by the findings of behavioral scientists. A process for critical analysis is proposed that solicits explicit accounting and cognizance of potential human biases. A number of suggestions are made to address the human challenges of IEM, in addition to maintaining attitudes of watchful humility, open-mindedness, honesty, and transparent accountability. These include creating a new area of study in the behavioral biogeosciences, using structured processes for engaging the modeling and stakeholder community in IEM, and using “red teams” to increase resilience of IEM constructs and use.

Is Gaydar Affected by Attitudes Toward Homosexuality? Confidence, Labeling Bias, and Accuracy.

PubMed

Brewer, Gayle; Lyons, Minna

2017-01-01

Previous research has largely ignored the relationship between sexual orientation judgement accuracy, confidence, and attitudes toward homosexuality. In an online study, participants (N = 269) judged the sexual orientation of homosexual and heterosexual targets presented via a series of facial photographs. Participants also indicated their confidence in each judgment and completed the Modern Homonegativity Scale (Morrison & Morrison, 2002). We found that (1) homosexual men and heterosexual women were more accurate when judging photographs of women as opposed to photographs of men, and (2) in heterosexual men, negative attitudes toward homosexual men predicted confidence and bias when rating men's photographs. Findings indicate that homosexual men and heterosexual women are similar in terms of accuracy in judging women's sexuality. Further, especially in men, homophobia is associated with cognitive biases in labeling other men but does not have a relationship with increased accuracy.

Physiological responses and partisan bias: beyond self-reported measures of party identification.

PubMed

Petersen, Michael Bang; Giessing, Ann; Nielsen, Jesper

2015-01-01

People are biased partisans: they tend to agree with policies from political parties they identify with, independent of policy content. Here, we investigate how physiological reactions to political parties shape bias. Using changes in galvanic skin conductance responses to the visual presentation of party logos, we obtained an implicit and physiological measure of the affective arousal associated with political parties. Subsequently, we exposed subjects to classical party cue experiments where the party sponsors of specific policies were experimentally varied. We found that partisan bias only obtains among those exhibiting a strong physiological reaction to the party source; being a self-reported party identifier is not sufficient on its own. This suggests that partisan bias is rooted in implicit, affective reactions.

Physiological Responses and Partisan Bias: Beyond Self-Reported Measures of Party Identification

PubMed Central

Petersen, Michael Bang; Giessing, Ann; Nielsen, Jesper

2015-01-01

People are biased partisans: they tend to agree with policies from political parties they identify with, independent of policy content. Here, we investigate how physiological reactions to political parties shape bias. Using changes in galvanic skin conductance responses to the visual presentation of party logos, we obtained an implicit and physiological measure of the affective arousal associated with political parties. Subsequently, we exposed subjects to classical party cue experiments where the party sponsors of specific policies were experimentally varied. We found that partisan bias only obtains among those exhibiting a strong physiological reaction to the party source; being a self-reported party identifier is not sufficient on its own. This suggests that partisan bias is rooted in implicit, affective reactions. PMID:26010527

Attention biases, anxiety, and development: Toward or away from threats or rewards?

PubMed Central

Shechner, Tomer; Britton, Jennifer C.; Pérez-Edgar, Koraly; Bar-Haim, Yair; Ernst, Monique; Fox, Nathan A.; Leibenluft, Ellen; Pine, Daniel S.

2012-01-01

Research on attention provides a promising framework for studying anxiety pathophysiology and treatment. The study of attention biases appears particularly pertinent to developmental research, as attention affects learning and has down-stream effects on behavior. This review summarizes recent findings about attention orienting in anxiety, drawing on findings in recent developmental psychopathology and affective neuroscience research. These findings generate specific insights about both development and therapeutics. The review goes beyond a traditional focus on biased processing of threats and considers biased processing of rewards. Building on this work, we then turn to treatment of pediatric anxiety, where manipulation of attention to threat and/or reward may serve a therapeutic role as a component of Attention Bias Modification Therapy. PMID:22170764

The Impact of Experiential Avoidance on the Inference of Characters' Emotions: Evidence for an Emotional Processing Bias.

PubMed

Pickett, Scott M; Kurby, Christopher A

2010-12-01

Experiential avoidance is a functional class of maladaptive strategies that contribute to the development and maintenance of psychopathology. Although previous research has demonstrated group differences in the interpretation of aversive stimuli, there is limited work on the influence of experiential avoidance during the online processing of emotion. An experimental design investigated the influence of self-reported experiential avoidance during emotion processing by assessing emotion inferences during the comprehension of narratives that imply different emotions. Results suggest that experiential avoidance is partially characterized by an emotional information processing bias. Specifically, individuals reporting higher experiential avoidance scores exhibited a bias towards activating negative emotion inferences, whereas individuals reporting lower experiential avoidance scores exhibited a bias towards activating positive emotion inferences. Minimal emotional inference was observed for the non-bias affective valence. Findings are discussed in terms of the implications of experiential avoidance as a cognitive vulnerability for psychopathology.

Debiasing the mind through meditation: mindfulness and the sunk-cost bias.

PubMed

Hafenbrack, Andrew C; Kinias, Zoe; Barsade, Sigal G

2014-02-01

In the research reported here, we investigated the debiasing effect of mindfulness meditation on the sunk-cost bias. We conducted four studies (one correlational and three experimental); the results suggest that increased mindfulness reduces the tendency to allow unrecoverable prior costs to influence current decisions. Study 1 served as an initial correlational demonstration of the positive relationship between trait mindfulness and resistance to the sunk-cost bias. Studies 2a and 2b were laboratory experiments examining the effect of a mindfulness-meditation induction on increased resistance to the sunk-cost bias. In Study 3, we examined the mediating mechanisms of temporal focus and negative affect, and we found that the sunk-cost bias was attenuated by drawing one's temporal focus away from the future and past and by reducing state negative affect, both of which were accomplished through mindfulness meditation.

Impact of chlorophyll bias on the tropical Pacific mean climate in an earth system model

NASA Astrophysics Data System (ADS)

Lim, Hyung-Gyu; Park, Jong-Yeon; Kug, Jong-Seong

2017-12-01

Climate modeling groups nowadays develop earth system models (ESMs) by incorporating biogeochemical processes in their climate models. The ESMs, however, often show substantial bias in simulated marine biogeochemistry which can potentially introduce an undesirable bias in physical ocean fields through biogeophysical interactions. This study examines how and how much the chlorophyll bias in a state-of-the-art ESM affects the mean and seasonal cycle of tropical Pacific sea-surface temperature (SST). The ESM used in the present study shows a sizeable positive bias in the simulated tropical chlorophyll. We found that the correction of the chlorophyll bias can reduce the ESM's intrinsic cold SST mean bias in the equatorial Pacific. The biologically-induced cold SST bias is strongly affected by seasonally-dependent air-sea coupling strength. In addition, the correction of chlorophyll bias can improve the annual cycle of SST by up to 25%. This result suggests a possible modeling approach in understanding the two-way interactions between physical and chlorophyll biases by biogeophysical effects.

Diffusion Modelling Reveals the Decision Making Processes Underlying Negative Judgement Bias in Rats

PubMed Central

Hales, Claire A.; Robinson, Emma S. J.; Houghton, Conor J.

2016-01-01

Human decision making is modified by emotional state. Rodents exhibit similar biases during interpretation of ambiguous cues that can be altered by affective state manipulations. In this study, the impact of negative affective state on judgement bias in rats was measured using an ambiguous-cue interpretation task. Acute treatment with an anxiogenic drug (FG7142), and chronic restraint stress and social isolation both induced a bias towards more negative interpretation of the ambiguous cue. The diffusion model was fit to behavioural data to allow further analysis of the underlying decision making processes. To uncover the way in which parameters vary together in relation to affective state manipulations, independent component analysis was conducted on rate of information accumulation and distances to decision threshold parameters for control data. Results from this analysis were applied to parameters from negative affective state manipulations. These projected components were compared to control components to reveal the changes in decision making processes that are due to affective state manipulations. Negative affective bias in rodents induced by either FG7142 or chronic stress is due to a combination of more negative interpretation of the ambiguous cue, reduced anticipation of the high reward and increased anticipation of the low reward. PMID:27023442

Diffusion Modelling Reveals the Decision Making Processes Underlying Negative Judgement Bias in Rats.

PubMed

Hales, Claire A; Robinson, Emma S J; Houghton, Conor J

2016-01-01

Human decision making is modified by emotional state. Rodents exhibit similar biases during interpretation of ambiguous cues that can be altered by affective state manipulations. In this study, the impact of negative affective state on judgement bias in rats was measured using an ambiguous-cue interpretation task. Acute treatment with an anxiogenic drug (FG7142), and chronic restraint stress and social isolation both induced a bias towards more negative interpretation of the ambiguous cue. The diffusion model was fit to behavioural data to allow further analysis of the underlying decision making processes. To uncover the way in which parameters vary together in relation to affective state manipulations, independent component analysis was conducted on rate of information accumulation and distances to decision threshold parameters for control data. Results from this analysis were applied to parameters from negative affective state manipulations. These projected components were compared to control components to reveal the changes in decision making processes that are due to affective state manipulations. Negative affective bias in rodents induced by either FG7142 or chronic stress is due to a combination of more negative interpretation of the ambiguous cue, reduced anticipation of the high reward and increased anticipation of the low reward.

Bias correction of daily satellite precipitation data using genetic algorithm

NASA Astrophysics Data System (ADS)

Pratama, A. W.; Buono, A.; Hidayat, R.; Harsa, H.

2018-05-01

Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS) was producted by blending Satellite-only Climate Hazards Group InfraRed Precipitation (CHIRP) with Stasion observations data. The blending process was aimed to reduce bias of CHIRP. However, Biases of CHIRPS on statistical moment and quantil values were high during wet season over Java Island. This paper presented a bias correction scheme to adjust statistical moment of CHIRP using observation precipitation data. The scheme combined Genetic Algorithm and Nonlinear Power Transformation, the results was evaluated based on different season and different elevation level. The experiment results revealed that the scheme robustly reduced bias on variance around 100% reduction and leaded to reduction of first, and second quantile biases. However, bias on third quantile only reduced during dry months. Based on different level of elevation, the performance of bias correction process is only significantly different on skewness indicators.

A shortened protocol for assessing cognitive bias in rats.

PubMed

Brydges, Nichola M; Hall, Lynsey

2017-07-15

Reliable measurement of affective state in animals is a significant goal of animal welfare. Such measurements would also improve the validity of pre-clinical mental health research which relies on animal models. However, at present, affective states in animals are inaccessible to direct measurement. In humans, changes in cognitive processing can give reliable indications of emotional state. Therefore, similar techniques are increasingly being used to gain proxy measures of affective states in animals. In particular, the 'cognitive bias' assay has gained popularity in recent years. Major disadvantages of this technique include length of time taken for animals to acquire the task (typically several weeks), negative experiences associated with task training, and issues of motivation. Here we present a shortened cognitive bias protocol using only positive reinforcers which must actively be responded to. The protocol took an average of 4days to complete, and produced similar results to previous, longer methods (minimum 30days). Specifically, rats housed in standard laboratory conditions demonstrated negative cognitive biases when presented with ambiguous stimuli, and took longer to make a decision when faced with an ambiguous stimulus. Compared to previous methods, this protocol is significantly shorter (average 4days vs. minimum 30days), utilises only positive reinforcers to avoid inducing negative affective states, and requires active responses to all cues, avoiding potential confounds of motivational state. We have successfully developed a shortened cognitive bias protocol, suitable for use with laboratory rats. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Nonresponse Bias to Mail Survey Questionnaires within a Professional Population.

ERIC Educational Resources Information Center

Hovland, Eric J.; And Others

1980-01-01

The possible bias resulting from excluding nonresponders in tabulating data from mail survey questionnaires in a dentist population was investigated. The differences between the responders and the nonresponders were analyzed with respect to the dentists' demographic data, attitudes, and knowledge. Nonresponse bias did not affect the results of…

Attention, interpretation, and memory biases in subclinical depression: a proof-of-principle test of the combined cognitive biases hypothesis.

PubMed

Everaert, Jonas; Duyck, Wouter; Koster, Ernst H W

2014-04-01

Emotional biases in attention, interpretation, and memory are viewed as important cognitive processes underlying symptoms of depression. To date, there is a limited understanding of the interplay among these processing biases. This study tested the dependence of memory on depression-related biases in attention and interpretation. Subclinically depressed and nondepressed participants completed a computerized version of the scrambled sentences test (measuring interpretation bias) while their eye movements were recorded (measuring attention bias). This task was followed by an incidental free recall test of previously constructed interpretations (measuring memory bias). Path analysis revealed a good fit for the model in which selective orienting of attention was associated with interpretation bias, which in turn was associated with a congruent bias in memory. Also, a good fit was observed for a path model in which biases in the maintenance of attention and interpretation were associated with memory bias. Both path models attained a superior fit compared with path models without the theorized functional relations among processing biases. These findings enhance understanding of how mechanisms of attention and interpretation regulate what is remembered. As such, they offer support for the combined cognitive biases hypothesis or the notion that emotionally biased cognitive processes are not isolated mechanisms but instead influence each other. Implications for theoretical models and emotion regulation across the spectrum of depressive symptoms are discussed.

Ligation Bias in Illumina Next-Generation DNA Libraries: Implications for Sequencing Ancient Genomes

PubMed Central

Seguin-Orlando, Andaine; Schubert, Mikkel; Clary, Joel; Stagegaard, Julia; Alberdi, Maria T.; Prado, José Luis; Prieto, Alfredo; Willerslev, Eske; Orlando, Ludovic

2013-01-01

Ancient DNA extracts consist of a mixture of endogenous molecules and contaminant DNA templates, often originating from environmental microbes. These two populations of templates exhibit different chemical characteristics, with the former showing depurination and cytosine deamination by-products, resulting from post-mortem DNA damage. Such chemical modifications can interfere with the molecular tools used for building second-generation DNA libraries, and limit our ability to fully characterize the true complexity of ancient DNA extracts. In this study, we first use fresh DNA extracts to demonstrate that library preparation based on adapter ligation at AT-overhangs are biased against DNA templates starting with thymine residues, contrarily to blunt-end adapter ligation. We observe the same bias on fresh DNA extracts sheared on Bioruptor, Covaris and nebulizers. This contradicts previous reports suggesting that this bias could originate from the methods used for shearing DNA. This also suggests that AT-overhang adapter ligation efficiency is affected in a sequence-dependent manner and results in an uneven representation of different genomic contexts. We then show how this bias could affect the base composition of ancient DNA libraries prepared following AT-overhang ligation, mainly by limiting the ability to ligate DNA templates starting with thymines and therefore deaminated cytosines. This results in particular nucleotide misincorporation damage patterns, deviating from the signature generally expected for authenticating ancient sequence data. Consequently, we show that models adequate for estimating post-mortem DNA damage levels must be robust to the molecular tools used for building ancient DNA libraries. PMID:24205269

A Principal Components Analysis of Dynamic Spatial Memory Biases

ERIC Educational Resources Information Center

Motes, Michael A.; Hubbard, Timothy L.; Courtney, Jon R.; Rypma, Bart

2008-01-01

Research has shown that spatial memory for moving targets is often biased in the direction of implied momentum and implied gravity, suggesting that representations of the subjective experiences of these physical principles contribute to such biases. The present study examined the association between these spatial memory biases. Observers viewed…

The role of ensemble-based statistics in variational assimilation of cloud-affected observations from infrared imagers

NASA Astrophysics Data System (ADS)

Hacker, Joshua; Vandenberghe, Francois; Jung, Byoung-Jo; Snyder, Chris

2017-04-01

Effective assimilation of cloud-affected radiance observations from space-borne imagers, with the aim of improving cloud analysis and forecasting, has proven to be difficult. Large observation biases, nonlinear observation operators, and non-Gaussian innovation statistics present many challenges. Ensemble-variational data assimilation (EnVar) systems offer the benefits of flow-dependent background error statistics from an ensemble, and the ability of variational minimization to handle nonlinearity. The specific benefits of ensemble statistics, relative to static background errors more commonly used in variational systems, have not been quantified for the problem of assimilating cloudy radiances. A simple experiment framework is constructed with a regional NWP model and operational variational data assimilation system, to provide the basis understanding the importance of ensemble statistics in cloudy radiance assimilation. Restricting the observations to those corresponding to clouds in the background forecast leads to innovations that are more Gaussian. The number of large innovations is reduced compared to the more general case of all observations, but not eliminated. The Huber norm is investigated to handle the fat tails of the distributions, and allow more observations to be assimilated without the need for strict background checks that eliminate them. Comparing assimilation using only ensemble background error statistics with assimilation using only static background error statistics elucidates the importance of the ensemble statistics. Although the cost functions in both experiments converge to similar values after sufficient outer-loop iterations, the resulting cloud water, ice, and snow content are greater in the ensemble-based analysis. The subsequent forecasts from the ensemble-based analysis also retain more condensed water species, indicating that the local environment is more supportive of clouds. In this presentation we provide details that explain the

The facing bias in biological motion perception: structure, kinematics, and body parts.

PubMed

Schouten, Ben; Troje, Nikolaus F; Verfaillie, Karl

2011-01-01

Depth-ambiguous point-light walkers (PLWs) elicit a facing bias: Observers perceive a PLW as facing toward them more often than as facing away (Vanrie,Dekeyser, & Verfaillie, Perception, 33, 547-560, 2004). While the facing bias correlates with the PLW's perceived gender (Brooks et al., Current Biology, 18, R728-R729, 2008; Schouten, Troje, Brooks, van der Zwan, & Verfaillie, Attention, Perception, & Psychophysics, 72,1256-1260, 2010), it remains unclear whether the change in perceived in-depth orientation is caused by a change in perceived gender. In Experiment 1, we show that structural and kinematic stimulus properties that lead to the same changes in perceived gender elicit opposite changes in perceived in-depth orientation, indicating that the relation between perceived gender and in-depth orientation is not causal. The results of Experiments 2 and 3 further suggest that the perceived in-depth orientation of PLWs is strongly affected by locally acting stimulus properties. The facing bias seems to be induced by stimulus properties in the lower part of the PLW.

Looking on the bright side: biased attention and the human serotonin transporter gene.

PubMed

Fox, Elaine; Ridgewell, Anna; Ashwin, Chris

2009-05-22

Humans differ in terms of biased attention for emotional stimuli and these biases can confer differential resilience and vulnerability to emotional disorders. Selective processing of positive emotional information, for example, is associated with enhanced sociability and well-being while a bias for negative material is associated with neuroticism and anxiety. A tendency to selectively avoid negative material might also be associated with mental health and well-being. The neurobiological mechanisms underlying these cognitive phenotypes are currently unknown. Here we show for the first time that allelic variation in the promotor region of the serotonin transporter gene (5-HTTLPR) is associated with differential biases for positive and negative affective pictures. Individuals homozygous for the long allele (LL) showed a marked bias to selectively process positive affective material alongside selective avoidance of negative affective material. This potentially protective pattern was absent among individuals carrying the short allele (S or SL). Thus, allelic variation on a common genetic polymorphism was associated with the tendency to selectively process positive or negative information. The current study is important in demonstrating a genotype-related alteration in a well-established processing bias, which is a known risk factor in determining both resilience and vulnerability to emotional disorders.

Guilt leads to enhanced facing-the-viewer bias

PubMed Central

Shen, Mowei; Zhu, Chengfeng; Liao, Huayu; Zhang, Haihang; Zhou, Jifan

2018-01-01

As an important moral emotion, guilt plays a critical role in social interaction. It has been found that people tended to exhibit prosocial behavior under circumstances of guilt. However, all extant studies have predominantly focused on the influence of guilt on macro-level behavior. So far, no study has investigated whether guilt affects people’s micro-level perception. The current study closes this gap by examining whether guilt affects one’s inclination to perceive approaching motion. We achieved this aim by probing a facing-the-viewer bias (FTV bias). Specifically, when an ambiguous walking biological motion display is presented to participants via the point-light display technique, participants tend to perceive a walking agent approaching them. We hypothesized that guilt modulated FTV bias. To test this hypothesis, we adopted a two-person situation induction task to induce guilt, whereby participants were induced to feel that because of their poor task performance, their partner did not receive a satisfactory payment. We found that when participants were told that the perceived biological motion was motion-captured from their partner, the FTV bias was significantly increased for guilty participants relative to neutral participants. However, when participants were informed that the perceived biological motion was from a third neutral agent, the FTV bias was not modulated by guilt. These results suggest that guilt influences one’s inclination to perceive approaching motion, but this effect is constrained to the person towards whom guilt is directed. PMID:29649338

Implications of CO Bias for Ozone and Methane Lifetime in a CCM

NASA Technical Reports Server (NTRS)

Strode, Sarah; Duncan, Bryan Neal; Yegorova, Elena; Douglass, Anne

2013-01-01

A low bias in carbon monoxide compared to observations at high latitudes is a common feature of chemistry climate models. CO bias can both indicate and contribute to a bias in modeled OH and methane lifetime. This study examines possible causes of CO bias in the ACCMIP simulation of the GEOSCCM, and considers how attributing the CO bias to uncertainty in CO emissions versus biases in other constituents impacts the relationship between CO bias and methane lifetime. We use a simplified model of CO tagged by source with specified OH to quantify the sensitivity of the CO bias to changes in CO emissions or OH concentration, comparing the modeled CO to surface and MOPITT observations. The simplified model shows that decreasing OH in the northern hemisphere removes most of the global mean and inter-hemispheric bias in surface CO. We then use results from this analysis to explore how adjusting CO sources in the CCM impacts the concentrations of ozone, OH and methane. The CCM simulation also exhibits biases in ozone and water vapor compared to observations. We use a parameterized CO-OH-CH4 model that takes ozone and water vapor as inputs to the parameterization to examine whether correcting water and ozone biases can alter OH enough to remove the CO bias. Through this analysis, we aim to better quantify the relationship between CO bias and model biases in ozone concentrations and methane lifetime.

Temperature trend biases

NASA Astrophysics Data System (ADS)

Venema, Victor; Lindau, Ralf

2016-04-01

In an accompanying talk we show that well-homogenized national dataset warm more than temperatures from global collections averaged over the region of common coverage. In this poster we want to present auxiliary work about possible biases in the raw observations and on how well relative statistical homogenization can remove trend biases. There are several possible causes of cooling biases, which have not been studied much. Siting could be an important factor. Urban stations tend to move away from the centre to better locations. Many stations started inside of urban areas and are nowadays more outside. Even for villages the temperature difference between the centre and edge can be 0.5°C. When a city station moves to an airport, which often happened around WWII, this takes the station (largely) out of the urban heat island. During the 20th century the Stevenson screen was established as the dominant thermometer screen. This screen protected the thermometer much better against radiation than earlier designs. Deficits of earlier measurement methods have artificially warmed the temperatures in the 19th century. Newer studies suggest we may have underestimated the size of this bias. Currently we are in a transition to Automatic Weather Stations. The net global effect of this transition is not clear at this moment. Irrigation on average decreases the 2m-temperature by about 1 degree centigrade. At the same time, irrigation has increased significantly during the last century. People preferentially live in irrigated areas and weather stations serve agriculture. Thus it is possible that there is a higher likelihood that weather stations are erected in irrigated areas than elsewhere. In this case irrigation could lead to a spurious cooling trend. In the Parallel Observations Science Team of the International Surface Temperature Initiative (ISTI-POST) we are studying influence of the introduction of Stevenson screens and Automatic Weather Stations using parallel measurements

Formal Classroom Observations: Factors That Affect Their Success

ERIC Educational Resources Information Center

Zaidi, Zeba

2017-01-01

Formal class room observation is a very delicate topic in any educational institution. It involves a series of emotions and sentiments that come with the package. In this paper, the researcher will attempt to analyze the factors that affect the process in a relatively significant manner and thereby contribute greatly to the success or failure of…

Spatiotemporal brain dynamics underlying attentional bias modifications.

PubMed

Sallard, Etienne; Hartmann, Lea; Ptak, Radek; Spierer, Lucas

2018-06-05

Exaggerated attentional biases toward specific elements of the environment contribute to the maintenance of several psychiatric conditions, such as biases to threatening faces in social anxiety. Although recent literature indicates that attentional bias modification may constitute an effective approach for psychiatric remediation, the underlying neurophysiological mechanisms remain unclear. We addressed this question by recording EEG in 24 healthy participants performing a modified dot-probe task in which pairs of neutral cues (colored shapes) were replaced by probe stimuli requiring a discrimination judgment. To induce an attentional bias toward or away from the cues, the probes were systematically presented either at the same or at the opposite position of a specific cue color. This paradigm enabled participants to spontaneously develop biases to initially unbiased, neutral cues, as measured by the response speed to the probe presented after the cues. Behavioral result indicated that the ABM procedure induced approach and avoidance biases. The influence of ABM on inhibitory control was assessed in a separated Go/NoGo task: Changes in AB did not influence participants' capacity to inhibit their responses to the cues. Attentional bias modification was associated with a topographic modulation of event-related potentials already 50-84 ms following the onset of the cues. Statistical analyses of distributed electrical source estimations revealed that the development of attentional biases was associated with decreased activity in the left temporo-parieto-occipital junction. These findings suggest that attentional bias modification affects early sensory processing phases related to the extraction of information based on stimulus saliency. Copyright © 2017. Published by Elsevier B.V.

Assessing climate change impacts on the rape stem weevil, Ceutorhynchus napi Gyll., based on bias- and non-bias-corrected regional climate change projections.

PubMed

Junk, J; Ulber, B; Vidal, S; Eickermann, M

2015-11-01

Agricultural production is directly affected by projected increases in air temperature and changes in precipitation. A multi-model ensemble of regional climate change projections indicated shifts towards higher air temperatures and changing precipitation patterns during the summer and winter seasons up to the year 2100 for the region of Goettingen (Lower Saxony, Germany). A second major controlling factor of the agricultural production is the infestation level by pests. Based on long-term field surveys and meteorological observations, a calibration of an existing model describing the migration of the pest insect Ceutorhynchus napi was possible. To assess the impacts of climate on pests under projected changing environmental conditions, we combined the results of regional climate models with the phenological model to describe the crop invasion of this species. In order to reduce systematic differences between the output of the regional climate models and observational data sets, two different bias correction methods were applied: a linear correction for air temperature and a quantile mapping approach for precipitation. Only the results derived from the bias-corrected output of the regional climate models showed satisfying results. An earlier onset, as well as a prolongation of the possible time window for the immigration of Ceutorhynchus napi, was projected by the majority of the ensemble members.

Assessing climate change impacts on the rape stem weevil, Ceutorhynchus napi Gyll., based on bias- and non-bias-corrected regional climate change projections

NASA Astrophysics Data System (ADS)

Junk, J.; Ulber, B.; Vidal, S.; Eickermann, M.

2015-11-01

Agricultural production is directly affected by projected increases in air temperature and changes in precipitation. A multi-model ensemble of regional climate change projections indicated shifts towards higher air temperatures and changing precipitation patterns during the summer and winter seasons up to the year 2100 for the region of Goettingen (Lower Saxony, Germany). A second major controlling factor of the agricultural production is the infestation level by pests. Based on long-term field surveys and meteorological observations, a calibration of an existing model describing the migration of the pest insect Ceutorhynchus napi was possible. To assess the impacts of climate on pests under projected changing environmental conditions, we combined the results of regional climate models with the phenological model to describe the crop invasion of this species. In order to reduce systematic differences between the output of the regional climate models and observational data sets, two different bias correction methods were applied: a linear correction for air temperature and a quantile mapping approach for precipitation. Only the results derived from the bias-corrected output of the regional climate models showed satisfying results. An earlier onset, as well as a prolongation of the possible time window for the immigration of Ceutorhynchus napi, was projected by the majority of the ensemble members.

Estimating Sampling Biases and Measurement Uncertainties of AIRS-AMSU-A Temperature and Water Vapor Observations Using MERRA Reanalysis

NASA Technical Reports Server (NTRS)

Hearty, Thomas J.; Savtchenko, Andrey K.; Tian, Baijun; Fetzer, Eric; Yung, Yuk L.; Theobald, Michael; Vollmer, Bruce; Fishbein, Evan; Won, Young-In

2014-01-01

We use MERRA (Modern Era Retrospective-Analysis for Research Applications) temperature and water vapor data to estimate the sampling biases of climatologies derived from the AIRS/AMSU-A (Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A) suite of instruments. We separate the total sampling bias into temporal and instrumental components. The temporal component is caused by the AIRS/AMSU-A orbit and swath that are not able to sample all of time and space. The instrumental component is caused by scenes that prevent successful retrievals. The temporal sampling biases are generally smaller than the instrumental sampling biases except in regions with large diurnal variations, such as the boundary layer, where the temporal sampling biases of temperature can be +/- 2 K and water vapor can be 10% wet. The instrumental sampling biases are the main contributor to the total sampling biases and are mainly caused by clouds. They are up to 2 K cold and greater than 30% dry over mid-latitude storm tracks and tropical deep convective cloudy regions and up to 20% wet over stratus regions. However, other factors such as surface emissivity and temperature can also influence the instrumental sampling bias over deserts where the biases can be up to 1 K cold and 10% wet. Some instrumental sampling biases can vary seasonally and/or diurnally. We also estimate the combined measurement uncertainties of temperature and water vapor from AIRS/AMSU-A and MERRA by comparing similarly sampled climatologies from both data sets. The measurement differences are often larger than the sampling biases and have longitudinal variations.

Comparison of whole-genome bisulfite sequencing library preparation strategies identifies sources of biases affecting DNA methylation data.

PubMed

Olova, Nelly; Krueger, Felix; Andrews, Simon; Oxley, David; Berrens, Rebecca V; Branco, Miguel R; Reik, Wolf

2018-03-15

Whole-genome bisulfite sequencing (WGBS) is becoming an increasingly accessible technique, used widely for both fundamental and disease-oriented research. Library preparation methods benefit from a variety of available kits, polymerases and bisulfite conversion protocols. Although some steps in the procedure, such as PCR amplification, are known to introduce biases, a systematic evaluation of biases in WGBS strategies is missing. We perform a comparative analysis of several commonly used pre- and post-bisulfite WGBS library preparation protocols for their performance and quality of sequencing outputs. Our results show that bisulfite conversion per se is the main trigger of pronounced sequencing biases, and PCR amplification builds on these underlying artefacts. The majority of standard library preparation methods yield a significantly biased sequence output and overestimate global methylation. Importantly, both absolute and relative methylation levels at specific genomic regions vary substantially between methods, with clear implications for DNA methylation studies. We show that amplification-free library preparation is the least biased approach for WGBS. In protocols with amplification, the choice of bisulfite conversion protocol or polymerase can significantly minimize artefacts. To aid with the quality assessment of existing WGBS datasets, we have integrated a bias diagnostic tool in the Bismark package and offer several approaches for consideration during the preparation and analysis of WGBS datasets.

Perceptual and Gaze Biases during Face Processing: Related or Not?

PubMed Central

Samson, Hélène; Fiori-Duharcourt, Nicole; Doré-Mazars, Karine; Lemoine, Christelle; Vergilino-Perez, Dorine

2014-01-01

Previous studies have demonstrated a left perceptual bias while looking at faces, due to the fact that observers mainly use information from the left side of a face (from the observer's point of view) to perform a judgment task. Such a bias is consistent with the right hemisphere dominance for face processing and has sometimes been linked to a left gaze bias, i.e. more and/or longer fixations on the left side of the face. Here, we recorded eye-movements, in two different experiments during a gender judgment task, using normal and chimeric faces which were presented above, below, right or left to the central fixation point or on it (central position). Participants performed the judgment task by remaining fixated on the fixation point or after executing several saccades (up to three). A left perceptual bias was not systematically found as it depended on the number of allowed saccades and face position. Moreover, the gaze bias clearly depended on the face position as the initial fixation was guided by face position and landed on the closest half-face, toward the center of gravity of the face. The analysis of the subsequent fixations revealed that observers move their eyes from one side to the other. More importantly, no apparent link between gaze and perceptual biases was found here. This implies that we do not look necessarily toward the side of the face that we use to make a gender judgment task. Despite the fact that these results may be limited by the absence of perceptual and gaze biases in some conditions, we emphasized the inter-individual differences observed in terms of perceptual bias, hinting at the importance of performing individual analysis and drawing attention to the influence of the method used to study this bias. PMID:24454927

Cognitive Remediation and Bias Modification Strategies in Mood and Anxiety Disorders

PubMed Central

Gold, Alexandra K.; Montana, Rebecca E.; Sylvia, Louisa G.; Nierenberg, Andrew A.; Deckersbach, Thilo

2016-01-01

Purpose of review Cognitive impairments and biases, which are prevalent in patients with mood and anxiety disorders, can affect quality of life and functioning. Traditional treatments are only insufficiently addressing these impairments and biases. We review the cognitive impairments and biases present in these disorders as well as treatments targeting these domains. Recent findings Interventions aimed at improving cognitive impairments and biases may help improve cognitive deficits and overall functioning in patients with mood and anxiety disorders. Direct comparisons of treatments for cognitive impairments or biases versus more traditional psychosocial interventions have produced diverse results. Summary Overall, treatments for cognitive impairments and cognitive biases warrant additional study in clinical trials. Future research should explore cognitive remediation and cognitive bias modification adjunctive to psychosocial treatments to optimize patient outcomes in mood and anxiety disorders. PMID:27917364

FIP bias in a sigmoidal active region

NASA Astrophysics Data System (ADS)

Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, Lidia; Green, L. M.; Steed, K.; Carlyle, J.

2014-01-01

We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) - coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359'' × 485''. Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ~1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration.

Development of Quantitative Reasoning and Gender Biases.

ERIC Educational Resources Information Center

Klaczynski, Paul A.; Aneja, Alka

2002-01-01

The relationship between higher order reasoning and sex bias was investigated among children 7, 9 and 11 years old. Children read arguments enhancing their own or other gender, then rated argument intelligence, judged other children based on observations, and justified their arguments. Findings showed that own-gender reasoning biases declined with…

Decision-making heuristics and biases across the life span.

PubMed

Strough, Jonell; Karns, Tara E; Schlosnagle, Leo

2011-10-01

We outline a contextual and motivational model of judgment and decision-making (JDM) biases across the life span. Our model focuses on abilities and skills that correspond to deliberative, experiential, and affective decision-making processes. We review research that addresses links between JDM biases and these processes as represented by individual differences in specific abilities and skills (e.g., fluid and crystallized intelligence, executive functioning, emotion regulation, personality traits). We focus on two JDM biases-the sunk-cost fallacy (SCF) and the framing effect. We trace the developmental trajectory of each bias from preschool through middle childhood, adolescence, early adulthood, and later adulthood. We conclude that life-span developmental trajectories differ depending on the bias investigated. Existing research suggests relative stability in the framing effect across the life span and decreases in the SCF with age, including in later life. We highlight directions for future research on JDM biases across the life span, emphasizing the need for process-oriented research and research that increases our understanding of JDM biases in people's everyday lives. © 2011 New York Academy of Sciences.

SU-F-I-80: Correction for Bias in a Channelized Hotelling Model Observer Caused by Temporally Variable Non-Stationary Noise

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

Favazza, C; Fetterly, K

2016-06-15

Purpose: Application of a channelized Hotelling model observer (CHO) over a wide range of x-ray angiography detector target dose (DTD) levels demonstrated substantial bias for conditions yielding low detectability indices (d’), including low DTD and small test objects. The purpose of this work was to develop theory and methods to correct this bias. Methods: A hypothesis was developed wherein the measured detectability index (d’b) for a known test object is positively biased by temporally variable non-stationary noise in the images. Hotelling’s T2 test statistic provided the foundation for a mathematical theory which accounts for independent contributions to the measured d’bmore » value from both the test object (d’o) and non-stationary noise (d’ns). Experimental methods were developed to directly estimate d’o by determining d’ns and subtracting it from d’b, in accordance with the theory. Specifically, d’ns was determined from two sets of images from which the traditional test object was withheld. This method was applied to angiography images with DTD levels in the range 0 to 240 nGy and for disk-shaped iodine-based contrast targets with diameters 0.5 to 4.0 mm. Results: Bias in d’ was evidenced by d’b values which exceeded values expected from a quantum limited imaging system and decreasing object size and DTD. d’ns increased with decreasing DTD, reaching a maximum of 2.6 for DTD = 0. Bias-corrected d’o estimates demonstrated sub-quantum limited performance of the x-ray angiography for low DTD. Findings demonstrated that the source of non-stationary noise was detector electronic readout noise. Conclusion: Theory and methods to estimate and correct bias in CHO measurements from temporally variable non-stationary noise were presented. The temporal non-stationary noise was shown to be due to electronic readout noise. This method facilitates accurate estimates of d’ values over a large range of object size and detector target dose.« less

An Observation-based Assessment of Instrument Requirements for a Future Precipitation Process Observing System

NASA Astrophysics Data System (ADS)

Nelson, E.; L'Ecuyer, T. S.; Wood, N.; Smalley, M.; Kulie, M.; Hahn, W.

2017-12-01

Global models exhibit substantial biases in the frequency, intensity, duration, and spatial scales of precipitation systems. Much of this uncertainty stems from an inadequate representation of the processes by which water is cycled between the surface and atmosphere and, in particular, those that govern the formation and maintenance of cloud systems and their propensity to form the precipitation. Progress toward improving precipitation process models requires observing systems capable of quantifying the coupling between the ice content, vertical mass fluxes, and precipitation yield of precipitating cloud systems. Spaceborne multi-frequency, Doppler radar offers a unique opportunity to address this need but the effectiveness of such a mission is heavily dependent on its ability to actually observe the processes of interest in the widest possible range of systems. Planning for a next generation precipitation process observing system should, therefore, start with a fundamental evaluation of the trade-offs between sensitivity, resolution, sampling, cost, and the overall potential scientific yield of the mission. Here we provide an initial assessment of the scientific and economic trade-space by evaluating hypothetical spaceborne multi-frequency radars using a combination of current real-world and model-derived synthetic observations. Specifically, we alter the field of view, vertical resolution, and sensitivity of a hypothetical Ka- and W-band radar system and propagate those changes through precipitation detection and intensity retrievals. The results suggest that sampling biases introduced by reducing sensitivity disproportionately affect the light rainfall and frozen precipitation regimes that are critical for warm cloud feedbacks and ice sheet mass balance, respectively. Coarser spatial resolution observations introduce regime-dependent biases in both precipitation occurrence and intensity that depend on cloud regime, with even the sign of the bias varying within a

Temperament differentially influences early information processing in men and women: Preliminary electrophysiological evidence of attentional biases in healthy individuals.

PubMed

Pintzinger, Nina M; Pfabigan, Daniela M; Pfau, Lorenz; Kryspin-Exner, Ilse; Lamm, Claus

2017-01-01

Preferential processing of threat-related information is a robust finding in anxiety disorders. The observation that attentional biases are also present in healthy individuals suggests factors other than clinical symptoms to play a role. Using a dot-probe paradigm while event-related potentials were recorded in 59 healthy adults, we investigated whether temperament and gender, both related to individual variation in anxiety levels, influence attentional processing. All participants showed protective attentional biases in terms of enhanced attention engagement with positive information, indexed by larger N1 amplitudes in positive compared to negative conditions. Taking gender differences into account, we observed that women showed enhanced attention engagement with negative compared to neutral information, indicated by larger P2 amplitudes in congruent than in incongruent negative conditions. Attentional processing was influenced by the temperament traits negative affect and effortful control. Our results emphasize that gender and temperament modulate attentional biases in healthy adults. Copyright © 2016 Elsevier B.V. All rights reserved.

Galaxy bias and primordial non-Gaussianity

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

Assassi, Valentin; Baumann, Daniel; Schmidt, Fabian, E-mail: assassi@ias.edu, E-mail: D.D.Baumann@uva.nl, E-mail: fabians@MPA-Garching.MPG.DE

2015-12-01

We present a systematic study of galaxy biasing in the presence of primordial non-Gaussianity. For a large class of non-Gaussian initial conditions, we define a general bias expansion and prove that it is closed under renormalization, thereby showing that the basis of operators in the expansion is complete. We then study the effects of primordial non-Gaussianity on the statistics of galaxies. We show that the equivalence principle enforces a relation between the scale-dependent bias in the galaxy power spectrum and that in the dipolar part of the bispectrum. This provides a powerful consistency check to confirm the primordial origin ofmore » any observed scale-dependent bias. Finally, we also discuss the imprints of anisotropic non-Gaussianity as motivated by recent studies of higher-spin fields during inflation.« less

Cognitive Bias for Learning Speech Sounds From a Continuous Signal Space Seems Nonlinguistic.

PubMed

van der Ham, Sabine; de Boer, Bart

2015-10-01

When learning language, humans have a tendency to produce more extreme distributions of speech sounds than those observed most frequently: In rapid, casual speech, vowel sounds are centralized, yet cross-linguistically, peripheral vowels occur almost universally. We investigate whether adults' generalization behavior reveals selective pressure for communication when they learn skewed distributions of speech-like sounds from a continuous signal space. The domain-specific hypothesis predicts that the emergence of sound categories is driven by a cognitive bias to make these categories maximally distinct, resulting in more skewed distributions in participants' reproductions. However, our participants showed more centered distributions, which goes against this hypothesis, indicating that there are no strong innate linguistic biases that affect learning these speech-like sounds. The centralization behavior can be explained by a lack of communicative pressure to maintain categories.

Attention bias modification in specific fears: Spiders versus snakes.

PubMed

Luo, Xijia; Ikani, Nessa; Barth, Anja; Rengers, Lea; Becker, Eni; Rinck, Mike

2015-12-01

Attention Bias Modification (ABM) is used to manipulate attention biases in anxiety disorders. It has been successful in reducing attention biases and anxious symptoms in social anxiety and generalized anxiety, but not yet in specific fears and phobias. We designed a new version of the dot-probe training task, aiming to train fearful participants' attention away from or towards pictures of threatening stimuli. Moreover, we studied whether the training also affected participants' avoidance behavior and their physical arousal upon being confronted with a real threat object. In Experiment 1, students with fear of spiders were trained. We found that the attention manipulation was successful, but the training failed to affect behavior or arousal. In Experiment 2, the same procedure was used on snake-fearful students. Again, attention was trained in the expected directions. Moreover, participants whose attention had been trained away from snakes showed lower physiological arousal upon being confronted with a real snake. The study involved healthy students with normal distribution of the fear of spider/snake. Future research with clinical sample could help with determining the generalizability of the current findings. The effect of ABM on specific phobia is still in question. The finding in the present study suggested the possibility to alter attentional bias with a dot-probe task with general positive stimuli and this training could even affect the behavior while encountering a real threat. Copyright © 2015 Elsevier Ltd. All rights reserved.

What causes the facing-the-viewer bias in biological motion?

PubMed

Weech, Séamas; McAdam, Matthew; Kenny, Sophie; Troje, Nikolaus F

2014-10-13

Orthographically projected biological motion point-light displays are generally ambiguous with respect to their orientation in depth, yet observers consistently prefer the facing-the-viewer interpretation. There has been discussion as to whether this bias can be attributed to the social relevance of biological motion stimuli or relates to local, low-level stimulus properties. In the present study we address this question. In Experiment 1, we compared the facing-the-viewer bias produced by a series of four stick figures and three human silhouettes that differed in posture, gender, and the presence versus absence of walking motion. Using a paradigm in which we asked observers to indicate the spinning direction of these figures, we found no bias when participants observed silhouettes, whereas a pronounced degree of bias was elicited by most stick figures. We hypothesized that the ambiguous surface normals on the lines and dots that comprise stick figures are prone to a visual bias that assumes surfaces to be convex. The local surface orientations of the occluding contours of silhouettes are unambiguous, and as such the convexity bias does not apply. In Experiment 2, we tested the role of local features in ambiguous surface perception by adding dots to the elbows and knees of silhouettes. We found biases consistent with the facing directions implied by a convex body surface. The results unify a number of findings regarding the facing-the-viewer bias. We conclude that the facing-the-viewer bias is established at the level of surface reconstruction from local image features rather than on a semantic level. © 2014 ARVO.

Influence of polarized bias and porous silicon morphology on the electrical behavior of Au-porous silicon contacts*

PubMed Central

Zhao, Yue; Li, Dong-sheng; Xing, Shou-xiang; Yang, De-ren; Jiang, Min-hua

2005-01-01

This paper reports the surface morphology and I-V curves of porous silicon (PS) samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the devices were operated under different external bias (10 V or 3 V) for 10 min, their observed obvious differences in electrical properties may be due to the different control mechanisms in the Al/PS interface and PS matrix morphology. PMID:16252350

Causes of the large warm bias in the Angola-Benguela Frontal Zone in the Norwegian Earth System Model

NASA Astrophysics Data System (ADS)

Koseki, Shunya; Keenlyside, Noel; Demissie, Teferi; Toniazzo, Thomas; Counillon, Francois; Bethke, Ingo; Ilicak, Mehmet; Shen, Mao-Lin

2018-06-01

We have investigated the causes of the sea surface temperature (SST) bias in the Angola-Benguela Frontal Zone (ABFZ) of the southeastern Atlantic Ocean simulated by the Norwegian Earth System Model (NorESM). Similar to other coupled-models, NorESM has a warm SST bias in the ABFZ of up to 8 °C in the annual mean. Our analysis of NorESM reveals that a cyclonic surface wind bias over the ABFZ drives a locally excessively strong southward (0.05 m/s (relative to observation)) Angola Current displacing the ABFZ southward. A series of uncoupled stand-alone atmosphere and ocean model simulations are performed to investigate the cause of the coupled model bias. The stand-alone atmosphere model driven with observed SST exhibits a similar cyclonic surface circulation bias; while the stand-alone ocean model forced with the reanalysis data produces a warm SST in the ABFZ with a magnitude approximately half of that in the coupled NorESM simulation. An additional uncoupled sensitivity experiment shows that the atmospheric model's local negative surface wind curl generates anomalously strong Angola Current at the ocean surface. Consequently, this contributes to the warm SST bias in the ABFZ by 2 °C (compared to the reanalysis forced simulation). There is no evidence that local air-sea feedbacks among wind stress curl, SST, and sea level pressure (SLP) affect the ABFZ SST bias. Turbulent surface heat flux differences between coupled and uncoupled experiments explain the remaining 2 °C warm SST bias in NorESM. Ocean circulation, upwelling and turbulent heat flux errors all modulate the intensity and the seasonality of the ABFZ errors.

Investigating diagnostic bias in autism spectrum conditions: An item response theory analysis of sex bias in the AQ-10.

PubMed

Murray, Aja Louise; Allison, Carrie; Smith, Paula L; Baron-Cohen, Simon; Booth, Tom; Auyeung, Bonnie

2017-05-01

Diagnostic bias is a concern in autism spectrum conditions (ASC) where prevalence and presentation differ by sex. To ensure that females with ASC are not under-identified, it is important that ASC screening tools do not systematically underestimate autistic traits in females relative to males. We evaluated whether the AQ-10, a brief screen for ASC recommended by the National Institute of Clinical Excellence in cases of suspected ASC, exhibits such a bias. Using an item response theory approach, we evaluated differential item functioning and differential test functioning. We found that although individual items showed some sex bias, these biases at times favored males and at other times favored females. Thus, at the level of test scores the item-level biases cancelled out to give an unbiased overall score. Results support the continued use of the AQ-10 sum score in its current form; however, suggest that caution should be exercised when interpreting responses to individual items. The nature of the item level biases could serve as a guide for future research into how ASC affects males and females differently. Autism Res 2017, 10: 790-800. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Describing Perceived Racial Bias Among Youth With Sickle Cell Disease.

PubMed

Wakefield, Emily O; Pantaleao, Ashley; Popp, Jill M; Dale, Lourdes P; Santanelli, James P; Litt, Mark D; Zempsky, William T

2018-03-17

Sickle cell disease (SCD) predominately affects Black Americans. This is the first study of its kind to describe the racial bias experiences of youth with SCD and their reactions to these experiences. Participants were 20 youth with SCD (ages 13-21 years) who were asked to describe any racial bias events they experienced, as recorded on the Perception of Racism in Children and Youth measure (PRaCY). Interviews were recorded, transcribed, and analyzed by two independent raters using a conventional content analysis approach. All participants reported at least one incident of racial bias. Content analysis of racial bias events (n = 104) yielded 4 categories and 12 subcategories as follows: Perpetrator (Peers, Authority Figures, and General Public), Type of Racial Bias (Explicit, Implicit), Behavioral Reaction (Approach, Avoidant), and Emotional Response (Dysphoria, Anger, Unconcerned, Inferior, Anxious). This study provides a description of racial bias experiences within community and medical settings and highlights the need for further evaluation of the impact of racial bias among youth with SCD.

Biases in GNSS-Data Processing

NASA Astrophysics Data System (ADS)

Schaer, S. C.; Dach, R.; Lutz, S.; Meindl, M.; Beutler, G.

2010-12-01

Within the Global Positioning System (GPS) traditionally different types of pseudo-range measurements (P-code, C/A-code) are available on the first frequency that are tracked by the receivers with different technologies. For that reason, P1-C1 and P1-P2 Differential Code Biases (DCB) need to be considered in a GPS data processing with a mix of different receiver types. Since the Block IIR-M series of GPS satellites also provide C/A-code on the second frequency, P2-C2 DCB need to be added to the list of biases for maintenance. Potential quarter-cycle biases between different phase observables (specifically L2P and L2C) are another issue. When combining GNSS (currently GPS and GLONASS), careful consideration of inter-system biases (ISB) is indispensable, in particular when an adequate combination of individual GLONASS clock correction results from different sources (using, e.g., different software packages) is intended. Facing the GPS and GLONASS modernization programs and the upcoming GNSS, like the European Galileo and the Chinese Compass, an increasing number of types of biases is expected. The Center for Orbit Determination in Europe (CODE) is monitoring these GPS and GLONASS related biases for a long time based on RINEX files of the tracking network of the International GNSS Service (IGS) and in the frame of the data processing as one of the global analysis centers of the IGS. Within the presentation we give an overview on the stability of the biases based on the monitoring. Biases derived from different sources are compared. Finally, we give an outlook on the potential handling of such biases with the big variety of signals and systems expected in the future.

Attention bias modification training under working memory load increases the magnitude of change in attentional bias.

PubMed

Clarke, Patrick J F; Branson, Sonya; Chen, Nigel T M; Van Bockstaele, Bram; Salemink, Elske; MacLeod, Colin; Notebaert, Lies

2017-12-01

Attention bias modification (ABM) procedures have shown promise as a therapeutic intervention, however current ABM procedures have proven inconsistent in their ability to reliably achieve the requisite change in attentional bias needed to produce emotional benefits. This highlights the need to better understand the precise task conditions that facilitate the intended change in attention bias in order to realise the therapeutic potential of ABM procedures. Based on the observation that change in attentional bias occurs largely outside conscious awareness, the aim of the current study was to determine if an ABM procedure delivered under conditions likely to preclude explicit awareness of the experimental contingency, via the addition of a working memory load, would contribute to greater change in attentional bias. Bias change was assessed among 122 participants in response to one of four ABM tasks given by the two experimental factors of ABM training procedure delivered either with or without working memory load, and training direction of either attend-negative or avoid-negative. Findings revealed that avoid-negative ABM procedure under working memory load resulted in significantly greater reductions in attentional bias compared to the equivalent no-load condition. The current findings will require replication with clinical samples to determine the utility of the current task for achieving emotional benefits. These present findings are consistent with the position that the addition of a working memory load may facilitate change in attentional bias in response to an ABM training procedure. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Battle over Studies of Faculty Bias

ERIC Educational Resources Information Center

Gravois, John

2007-01-01

The American Federation of Teachers (AFT) recently commissioned a study to review the research that finds liberal bias run amok in academe. Believing that the AFT is not a dispassionate observer of this debate, this article provides "The Chronicle of Higher Education's" survey of the genre. The studies reviewed include: (1) "Political Bias in the…

Lateral bias in theatre-seat choice.

PubMed

Harms, Victoria; Reese, Miriam; Elias, Lorin J

2014-01-01

Examples of behavioural asymmetries are common in the range of human behaviour; even when faced with a symmetrical environment people demonstrate reliable asymmetries in behaviours like gesturing, cradling, and even seating. One such asymmetry is the observation that participants tend to choose seats to the right of the screen when asked to select their preferred seating location in a movie theatre. However, these results are based on seat selection using a seating chart rather than examining real seat choice behaviour in the theatre context. This study investigated the real-world seating patterns of theatre patrons during actual film screenings. Analysis of bias scores calculated using photographs of theatre patrons revealed a significant bias to choose seats on the right side of the theatre. These findings are consistent with the prior research in the area and confirm that the seating bias observed when seats are selected from a chart accurately reflects real-world seating behaviour.

Attentional bias for affective visual stimuli in posttraumatic stress disorder and the role of depression.

PubMed

Hauschildt, Marit; Wittekind, Charlotte; Moritz, Steffen; Kellner, Michael; Jelinek, Lena

2013-05-15

An attentional bias for trauma-related verbal cues was frequently demonstrated in posttraumatic stress disorder (PTSD) using variants of the emotional Stroop task (EST). However, the mechanisms underlying the Stroop-effect are ill-defined and it is yet unclear how the findings apply to different paradigms and stimulus modalities. To address these open questions, for the first time a spatial-cuing task with pictorial cues of different emotional valence was administered to trauma-exposed individuals with and without PTSD, and non-trauma-exposed controls. Groups did not show different response profiles across affective conditions. However, a group effect was evident when comparing depressed with non-depressed individuals: Those with depression showed delayed attending towards trauma-related cues and faster attending away from negative cues. In correlational analyses, attentional avoidance was associated with both depression and PTSD symptom severity. These findings highlight the need for research on trauma populations and anxiety in general to pay closer attention to depression as an important confound in the study of emotional information processing. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Apparatus bias and place conditioning with ethanol in mice.

PubMed

Cunningham, Christopher L; Ferree, Nikole K; Howard, MacKenzie A

2003-12-01

ethanol was paired with the initially non-preferred cue, and not when it was paired with the initially preferred cue. These conclusions held regardless of which dependent variable was used to index place conditioning, but only if the counterbalancing factor was included in statistical analyses. These studies indicate that apparatus bias plays a major role in determining whether biased assignment of an ethanol-paired stimulus affects ability to demonstrate conditioned place preference. Ethanol's ability to produce conditioned place preference in an unbiased apparatus, regardless of the direction of the initial cue bias, supports previous studies that interpret such findings as evidence of a primary rewarding drug effect. Moreover, these studies suggest that the asymmetrical outcome observed in the biased apparatus is most likely due to a measurement problem (e.g., ceiling effect) rather than to an interaction between the drug's effect and an unconditioned motivational response (e.g., "anxiety") to the initially non-preferred stimulus. More generally, these findings illustrate the importance of providing clear information on apparatus bias in all place-conditioning studies.

Calibration of colour gradient bias in shear measurement using HST/CANDELS data

NASA Astrophysics Data System (ADS)

Er, X.; Hoekstra, H.; Schrabback, T.; Cardone, V. F.; Scaramella, R.; Maoli, R.; Vicinanza, M.; Gillis, B.; Rhodes, J.

2018-06-01

Accurate shape measurements are essential to infer cosmological parameters from large area weak gravitational lensing studies. The compact diffraction-limited point spread function (PSF) in space-based observations is greatly beneficial, but its chromaticity for a broad-band observation can lead to new subtle effects that could hitherto be ignored: the PSF of a galaxy is no longer uniquely defined and spatial variations in the colours of galaxies result in biases in the inferred lensing signal. Taking Euclid as a reference, we show that this colour gradient bias (CG bias) can be quantified with high accuracy using available multicolour Hubble Space Telescope (HST) data. In particular we study how noise in the HST observations might impact such measurements and find this to be negligible. We determine the CG bias using HST observations in the F606W and F814W filters and observe a correlation with the colour, in line with expectations, whereas the dependence with redshift is weak. The biases for individual galaxies are generally well below 1 per cent, which may be reduced further using morphological information from the Euclid data. Our results demonstrate that CG bias should not be ignored, but it is possible to determine its amplitude with sufficient precision, so that it will not significantly bias the weak lensing measurements using Euclid data.

Decoupling global biases and local interactions between cell biological variables

PubMed Central

Zaritsky, Assaf; Obolski, Uri; Gan, Zhuo; Reis, Carlos R; Kadlecova, Zuzana; Du, Yi; Schmid, Sandra L; Danuser, Gaudenz

2017-01-01

Analysis of coupled variables is a core concept of cell biological inference, with co-localization of two molecules as a proxy for protein interaction being a ubiquitous example. However, external effectors may influence the observed co-localization independently from the local interaction of two proteins. Such global bias, although biologically meaningful, is often neglected when interpreting co-localization. Here, we describe DeBias, a computational method to quantify and decouple global bias from local interactions between variables by modeling the observed co-localization as the cumulative contribution of a global and a local component. We showcase four applications of DeBias in different areas of cell biology, and demonstrate that the global bias encapsulates fundamental mechanistic insight into cellular behavior. The DeBias software package is freely accessible online via a web-server at https://debias.biohpc.swmed.edu. DOI: http://dx.doi.org/10.7554/eLife.22323.001 PMID:28287393

Characterizing sampling and quality screening biases in infrared and microwave limb sounding

NASA Astrophysics Data System (ADS)

Millán, Luis F.; Livesey, Nathaniel J.; Santee, Michelle L.; von Clarmann, Thomas

2018-03-01

This study investigates orbital sampling biases and evaluates the additional impact caused by data quality screening for the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the Aura Microwave Limb Sounder (MLS). MIPAS acts as a proxy for typical infrared limb emission sounders, while MLS acts as a proxy for microwave limb sounders. These biases were calculated for temperature and several trace gases by interpolating model fields to real sampling patterns and, additionally, screening those locations as directed by their corresponding quality criteria. Both instruments have dense uniform sampling patterns typical of limb emission sounders, producing almost identical sampling biases. However, there is a substantial difference between the number of locations discarded. MIPAS, as a mid-infrared instrument, is very sensitive to clouds, and measurements affected by them are thus rejected from the analysis. For example, in the tropics, the MIPAS yield is strongly affected by clouds, while MLS is mostly unaffected. The results show that upper-tropospheric sampling biases in zonally averaged data, for both instruments, can be up to 10 to 30 %, depending on the species, and up to 3 K for temperature. For MIPAS, the sampling reduction due to quality screening worsens the biases, leading to values as large as 30 to 100 % for the trace gases and expanding the 3 K bias region for temperature. This type of sampling bias is largely induced by the geophysical origins of the screening (e.g. clouds). Further, analysis of long-term time series reveals that these additional quality screening biases may affect the ability to accurately detect upper-tropospheric long-term changes using such data. In contrast, MLS data quality screening removes sufficiently few points that no additional bias is introduced, although its penetration is limited to the upper troposphere, while MIPAS may cover well into the mid-troposphere in cloud-free scenarios. We emphasize that the

Fluid simulation of the bias effect in inductive/capacitive discharges

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

Zhang, Yu-Ru; Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, Wilrijk, BE-2610 Antwerp; Gao, Fei

Computer simulations are performed for an argon inductively coupled plasma (ICP) with a capacitive radio-frequency bias power, to investigate the bias effect on the discharge mode transition and on the plasma characteristics at various ICP currents, bias voltages, and bias frequencies. When the bias frequency is fixed at 13.56 MHz and the ICP current is low, e.g., 6 A, the spatiotemporal averaged plasma density increases monotonically with bias voltage, and the bias effect is already prominent at a bias voltage of 90 V. The maximum of the ionization rate moves toward the bottom electrode, which indicates clearly the discharge mode transition in inductive/capacitivemore » discharges. At higher ICP currents, i.e., 11 and 13 A, the plasma density decreases first and then increases with bias voltage, due to the competing mechanisms between the ion acceleration power dissipation and the capacitive power deposition. At 11 A, the bias effect is still important, but it is noticeable only at higher bias voltages. At 13 A, the ionization rate is characterized by a maximum at the reactor center near the dielectric window at all selected bias voltages, which indicates that the ICP power, instead of the bias power, plays a dominant role under this condition, and no mode transition is observed. Indeed, the ratio of the bias power to the total power is lower than 0.4 over a wide range of bias voltages, i.e., 0–300 V. Besides the effect of ICP current, also the effect of various bias frequencies is investigated. It is found that the modulation of the bias power to the spatiotemporal distributions of the ionization rate at 2 MHz is strikingly different from the behavior observed at higher bias frequencies. Furthermore, the minimum of the plasma density appears at different bias voltages, i.e., 120 V at 2 MHz and 90 V at 27.12 MHz.« less

Estimation of attitude sensor timetag biases

NASA Technical Reports Server (NTRS)

Sedlak, J.

1995-01-01

This paper presents an extended Kalman filter for estimating attitude sensor timing errors. Spacecraft attitude is determined by finding the mean rotation from a set of reference vectors in inertial space to the corresponding observed vectors in the body frame. Any timing errors in the observations can lead to attitude errors if either the spacecraft is rotating or the reference vectors themselves vary with time. The state vector here consists of the attitude quaternion, timetag biases, and, optionally, gyro drift rate biases. The filter models the timetags as random walk processes: their expectation values propagate as constants and white noise contributes to their covariance. Thus, this filter is applicable to cases where the true timing errors are constant or slowly varying. The observability of the state vector is studied first through an examination of the algebraic observability condition and then through several examples with simulated star tracker timing errors. The examples use both simulated and actual flight data from the Extreme Ultraviolet Explorer (EUVE). The flight data come from times when EUVE had a constant rotation rate, while the simulated data feature large angle attitude maneuvers. The tests include cases with timetag errors on one or two sensors, both constant and time-varying, and with and without gyro bias errors. Due to EUVE's sensor geometry, the observability of the state vector is severely limited when the spacecraft rotation rate is constant. In the absence of attitude maneuvers, the state elements are highly correlated, and the state estimate is unreliable. The estimates are particularly sensitive to filter mistuning in this case. The EUVE geometry, though, is a degenerate case having coplanar sensors and rotation vector. Observability is much improved and the filter performs well when the rate is either varying or noncoplanar with the sensors, as during a slew. Even with bad geometry and constant rates, if gyro biases are

Anticipation or ascertainment bias in schizophrenia? Penrose`s familial mental illness sample

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

Bassett, A.S.; Husted, J.

Several studies have observed anticipation (earlier age at onset [AAO] in successive generations) in familial schizophrenia. However, whether true anticipation or ascertainment bias is the principal originating mechanism remains unclear. In 1944 L.S. Penrose collected AAO data on a large, representative sample of familial mental illness, using a broad ascertainment strategy. These data allowed examination of anticipation and ascertainment biases in five two-generation samples of affected relative pairs. The median intergenerational difference (MID) in AAO was used to assess anticipation. Results showed significant anticipation in parent-offspring pairs with schizophrenia (n = 137 pairs; MID 15 years; P = .0001) andmore » in a positive control sample with Huntington disease (n = 11; P = .01). Broadening the diagnosis of the schizophrenia sample suggested anticipation of severity of illness. However, other analyses provided evidence for ascertainment bias, especially in later-AAO parents, in parent-offspring pairs. Aunt/uncle-niece/nephew schizophrenia pairs showed anticipation (n = 111; P = .0001), but the MID was 8 years and aunts/uncles had earlier median AAO than parents. Anticipation effects were greatest in pairs with late-AAO parents but remained significant in a subgroup of schizophrenia pairs with early parental AAO (n = 31; P = .03). A small control sample of other diseases had MID of 5 years but no significant anticipation (n = 9; F = .38). These results suggest that, although ascertainment-bias effects were observed in parent-offspring pairs, true anticipation appears to be inherent in the transmission of familial schizophrenia. The findings support investigations of unstable mutations and other mechanisms that may contribute to true anticipation in schizophrenia. 37 refs., 2 tabs.« less

Affect, affective disorder and schizophrenia. A neuropsychological investigation of right hemisphere function.

PubMed

David, A S; Cutting, J C

1990-04-01

Performance on a happy-sad chimeric face test was used to examine the role of right hemisphere activation in positive and negative affect, both normal and abnormal, as well as in schizophrenia. This test is known to elicit a left-sided perceptual bias in right-handed normal subjects. Happy and sad mood in normals did not influence the perceptual bias. Depression and mania were associated with reduced and increased biases respectively, while schizophrenics showed no bias to either side. Possible explanations are right hemisphere hyperfunction in mania, moderate relative hypofunction in depression, and severe relative hypofunction in schizophrenia. The marked difference between mania and schizophrenia supports distinct pathophysiologies underlying the two conditions.

Group bias in cooperative norm enforcement

PubMed Central

McAuliffe, Katherine; Dunham, Yarrow

2016-01-01

A hallmark of human social cognition is the tendency for both adults and children to favour members of their own groups. Critically, this in-group bias exerts a strong influence on cooperative decision-making: people (i) tend to share more with members of their in-group and (ii) differentially enforce fairness norms depending on the group membership of their interaction partners. But why do people show these group biases in cooperation? One possibility is that the enforcement of cooperative norm violations is an evolved mechanism supporting within-group cooperation (Norms-Focused Hypothesis). Alternatively, group bias in cooperation could be a by-product of more general affective preferences for in-group members (Mere Preferences Hypothesis). Here, we appraise evidence from studies of both adults and children with the goal of understanding whether one of these two accounts is better supported by existing data. While the pattern of evidence is complex, much of it is broadly consistent with the Mere Preferences Hypothesis and little is uniquely supportive of the Norms-Focused Hypothesis. We highlight possible reasons for this complexity and suggest ways that future work can continue to help us understand the important relationship between group bias and cooperation. PMID:26644592

Attentional bias modulation by reappraisal in patients with generalized anxiety disorder: an event-related potential study

PubMed Central

Han, H.Y.; Gan, T.; Li, P.; Li, Z.J.; Guo, M.; Yao, S.M.

2014-01-01

Affective states influence subsequent attention allocation. We evaluated emotional negativity bias modulation by reappraisal in patients with generalized anxiety disorder (GAD) relative to normal controls. Event-related potential (ERP) recordings were obtained, and changes in P200 and P300 amplitudes in response to negative or neutral words were noted after decreasing negative emotion or establishing a neutral condition. We found that in GAD patients only, the mean P200 amplitude after negative word presentation was much higher than after the presentation of neutral words. In normal controls, after downregulation of negative emotion, the mean P300 amplitude in response to negative words was much lower than after neutral words, and this was significant in both the left and right regions. In GAD patients, the negative bias remained prominent and was not affected by reappraisal at the early stage. Reappraisal was observed to have a lateralized effect at the late stage. PMID:24863650

Instrumental variables as bias amplifiers with general outcome and confounding.

PubMed

Ding, P; VanderWeele, T J; Robins, J M

2017-06-01

Drawing causal inference with observational studies is the central pillar of many disciplines. One sufficient condition for identifying the causal effect is that the treatment-outcome relationship is unconfounded conditional on the observed covariates. It is often believed that the more covariates we condition on, the more plausible this unconfoundedness assumption is. This belief has had a huge impact on practical causal inference, suggesting that we should adjust for all pretreatment covariates. However, when there is unmeasured confounding between the treatment and outcome, estimators adjusting for some pretreatment covariate might have greater bias than estimators without adjusting for this covariate. This kind of covariate is called a bias amplifier, and includes instrumental variables that are independent of the confounder, and affect the outcome only through the treatment. Previously, theoretical results for this phenomenon have been established only for linear models. We fill in this gap in the literature by providing a general theory, showing that this phenomenon happens under a wide class of models satisfying certain monotonicity assumptions. We further show that when the treatment follows an additive or multiplicative model conditional on the instrumental variable and the confounder, these monotonicity assumptions can be interpreted as the signs of the arrows of the causal diagrams.

Decision-making heuristics and biases across the life span

PubMed Central

Strough, JoNell; Karns, Tara E.; Schlosnagle, Leo

2013-01-01

We outline a contextual and motivational model of judgment and decision-making (JDM) biases across the life span. Our model focuses on abilities and skills that correspond to deliberative, experiential, and affective decision-making processes. We review research that addresses links between JDM biases and these processes as represented by individual differences in specific abilities and skills (e.g., fluid and crystallized intelligence, executive functioning, emotion regulation, personality traits). We focus on two JDM biases—the sunk-cost fallacy (SCF) and the framing effect. We trace the developmental trajectory of each bias from preschool through middle childhood, adolescence, early adulthood, and later adulthood. We conclude that life-span developmental trajectories differ depending on the bias investigated. Existing research suggests relative stability in the framing effect across the life span and decreases in the SCF with age, including in later life. We highlight directions for future research on JDM biases across the life span, emphasizing the need for process-oriented research and research that increases our understanding of JDM biases in people’s everyday lives. PMID:22023568

Bias to experience approaching motion in a three-dimensional virtual environment.

PubMed

Lewis, Clifford F; McBeath, Michael K

2004-01-01

We used two-frame apparent motion in a three-dimensional virtual environment to test whether observers had biases to experience approaching or receding motion in depth. Observers viewed a tunnel of tiles receding in depth, that moved ambiguously either toward or away from them. We found that observers exhibited biases to experience approaching motion. The strengths of the biases were decreased when stimuli pointed away, but size of the display screen had no effect. Tests with diamond-shaped tiles that varied in the degree of pointing asymmetry resulted in a linear trend in which the bias was strongest for stimuli pointing toward the viewer, and weakest for stimuli pointing away. We show that the overall bias to experience approaching motion is consistent with a computational strategy of matching corresponding features between adjacent foreshortened stimuli in consecutive visual frames. We conclude that there are both adaptational and geometric reasons to favor the experience of approaching motion.

Double propensity-score adjustment: A solution to design bias or bias due to incomplete matching.

PubMed

Austin, Peter C

2017-02-01

Propensity-score matching is frequently used to reduce the effects of confounding when using observational data to estimate the effects of treatments. Matching allows one to estimate the average effect of treatment in the treated. Rosenbaum and Rubin coined the term "bias due to incomplete matching" to describe the bias that can occur when some treated subjects are excluded from the matched sample because no appropriate control subject was available. The presence of incomplete matching raises important questions around the generalizability of estimated treatment effects to the entire population of treated subjects. We describe an analytic solution to address the bias due to incomplete matching. Our method is based on using optimal or nearest neighbor matching, rather than caliper matching (which frequently results in the exclusion of some treated subjects). Within the sample matched on the propensity score, covariate adjustment using the propensity score is then employed to impute missing potential outcomes under lack of treatment for each treated subject. Using Monte Carlo simulations, we found that the proposed method resulted in estimates of treatment effect that were essentially unbiased. This method resulted in decreased bias compared to caliper matching alone and compared to either optimal matching or nearest neighbor matching alone. Caliper matching alone resulted in design bias or bias due to incomplete matching, while optimal matching or nearest neighbor matching alone resulted in bias due to residual confounding. The proposed method also tended to result in estimates with decreased mean squared error compared to when caliper matching was used.

Double propensity-score adjustment: A solution to design bias or bias due to incomplete matching

PubMed Central

2016-01-01

Propensity-score matching is frequently used to reduce the effects of confounding when using observational data to estimate the effects of treatments. Matching allows one to estimate the average effect of treatment in the treated. Rosenbaum and Rubin coined the term “bias due to incomplete matching” to describe the bias that can occur when some treated subjects are excluded from the matched sample because no appropriate control subject was available. The presence of incomplete matching raises important questions around the generalizability of estimated treatment effects to the entire population of treated subjects. We describe an analytic solution to address the bias due to incomplete matching. Our method is based on using optimal or nearest neighbor matching, rather than caliper matching (which frequently results in the exclusion of some treated subjects). Within the sample matched on the propensity score, covariate adjustment using the propensity score is then employed to impute missing potential outcomes under lack of treatment for each treated subject. Using Monte Carlo simulations, we found that the proposed method resulted in estimates of treatment effect that were essentially unbiased. This method resulted in decreased bias compared to caliper matching alone and compared to either optimal matching or nearest neighbor matching alone. Caliper matching alone resulted in design bias or bias due to incomplete matching, while optimal matching or nearest neighbor matching alone resulted in bias due to residual confounding. The proposed method also tended to result in estimates with decreased mean squared error compared to when caliper matching was used. PMID:25038071

Cognitive debiasing 1: origins of bias and theory of debiasing.

PubMed

Croskerry, Pat; Singhal, Geeta; Mamede, Sílvia

2013-10-01

Numerous studies have shown that diagnostic failure depends upon a variety of factors. Psychological factors are fundamental in influencing the cognitive performance of the decision maker. In this first of two papers, we discuss the basics of reasoning and the Dual Process Theory (DPT) of decision making. The general properties of the DPT model, as it applies to diagnostic reasoning, are reviewed. A variety of cognitive and affective biases are known to compromise the decision-making process. They mostly appear to originate in the fast intuitive processes of Type 1 that dominate (or drive) decision making. Type 1 processes work well most of the time but they may open the door for biases. Removing or at least mitigating these biases would appear to be an important goal. We will also review the origins of biases. The consensus is that there are two major sources: innate, hard-wired biases that developed in our evolutionary past, and acquired biases established in the course of development and within our working environments. Both are associated with abbreviated decision making in the form of heuristics. Other work suggests that ambient and contextual factors may create high risk situations that dispose decision makers to particular biases. Fatigue, sleep deprivation and cognitive overload appear to be important determinants. The theoretical basis of several approaches towards debiasing is then discussed. All share a common feature that involves a deliberate decoupling from Type 1 intuitive processing and moving to Type 2 analytical processing so that eventually unexamined intuitive judgments can be submitted to verification. This decoupling step appears to be the critical feature of cognitive and affective debiasing.

Cognitive debiasing 1: origins of bias and theory of debiasing

PubMed Central

Croskerry, Pat; Singhal, Geeta; Mamede, Sílvia

2013-01-01

Numerous studies have shown that diagnostic failure depends upon a variety of factors. Psychological factors are fundamental in influencing the cognitive performance of the decision maker. In this first of two papers, we discuss the basics of reasoning and the Dual Process Theory (DPT) of decision making. The general properties of the DPT model, as it applies to diagnostic reasoning, are reviewed. A variety of cognitive and affective biases are known to compromise the decision-making process. They mostly appear to originate in the fast intuitive processes of Type 1 that dominate (or drive) decision making. Type 1 processes work well most of the time but they may open the door for biases. Removing or at least mitigating these biases would appear to be an important goal. We will also review the origins of biases. The consensus is that there are two major sources: innate, hard-wired biases that developed in our evolutionary past, and acquired biases established in the course of development and within our working environments. Both are associated with abbreviated decision making in the form of heuristics. Other work suggests that ambient and contextual factors may create high risk situations that dispose decision makers to particular biases. Fatigue, sleep deprivation and cognitive overload appear to be important determinants. The theoretical basis of several approaches towards debiasing is then discussed. All share a common feature that involves a deliberate decoupling from Type 1 intuitive processing and moving to Type 2 analytical processing so that eventually unexamined intuitive judgments can be submitted to verification. This decoupling step appears to be the critical feature of cognitive and affective debiasing. PMID:23882089

Increasing Principal Preparation Candidates' Awareness of Biases in Educational Environments

ERIC Educational Resources Information Center

Jones, Karen D.; Ringler, Marjorie C.

2017-01-01

The purpose of the study was to determine whether the study of diversity topics embedded in a Principal Preparation Program (PPP) internship changed candidates' self-awareness of their biases in educational environments and the biases they observed in their school community. In this study PPP candidates' perceptions of their biases and those of…

Biased lineup instructions and face identification from video images.

PubMed

Thompson, W Burt; Johnson, Jaime

2008-01-01

Previous eyewitness memory research has shown that biased lineup instructions reduce identification accuracy, primarily by increasing false-positive identifications in target-absent lineups. Because some attempts at identification do not rely on a witness's memory of the perpetrator but instead involve matching photos to images on surveillance video, the authors investigated the effects of biased instructions on identification accuracy in a matching task. In Experiment 1, biased instructions did not affect the overall accuracy of participants who used video images as an identification aid, but nearly all correct decisions occurred with target-present photo spreads. Both biased and unbiased instructions resulted in high false-positive rates. In Experiment 2, which focused on video-photo matching accuracy with target-absent photo spreads, unbiased instructions led to more correct responses (i.e., fewer false positives). These findings suggest that investigators should not relax precautions against biased instructions when people attempt to match photos to an unfamiliar person recorded on video.

Cognitive Bias for Learning Speech Sounds From a Continuous Signal Space Seems Nonlinguistic

PubMed Central

de Boer, Bart

2015-01-01

When learning language, humans have a tendency to produce more extreme distributions of speech sounds than those observed most frequently: In rapid, casual speech, vowel sounds are centralized, yet cross-linguistically, peripheral vowels occur almost universally. We investigate whether adults’ generalization behavior reveals selective pressure for communication when they learn skewed distributions of speech-like sounds from a continuous signal space. The domain-specific hypothesis predicts that the emergence of sound categories is driven by a cognitive bias to make these categories maximally distinct, resulting in more skewed distributions in participants’ reproductions. However, our participants showed more centered distributions, which goes against this hypothesis, indicating that there are no strong innate linguistic biases that affect learning these speech-like sounds. The centralization behavior can be explained by a lack of communicative pressure to maintain categories. PMID:27648212

On the linearity of tracer bias around voids

NASA Astrophysics Data System (ADS)

Pollina, Giorgia; Hamaus, Nico; Dolag, Klaus; Weller, Jochen; Baldi, Marco; Moscardini, Lauro

2017-07-01

The large-scale structure of the Universe can be observed only via luminous tracers of the dark matter. However, the clustering statistics of tracers are biased and depend on various properties, such as their host-halo mass and assembly history. On very large scales, this tracer bias results in a constant offset in the clustering amplitude, known as linear bias. Towards smaller non-linear scales, this is no longer the case and tracer bias becomes a complicated function of scale and time. We focus on tracer bias centred on cosmic voids, I.e. depressions of the density field that spatially dominate the Universe. We consider three types of tracers: galaxies, galaxy clusters and active galactic nuclei, extracted from the hydrodynamical simulation Magneticum Pathfinder. In contrast to common clustering statistics that focus on auto-correlations of tracers, we find that void-tracer cross-correlations are successfully described by a linear bias relation. The tracer-density profile of voids can thus be related to their matter-density profile by a single number. We show that it coincides with the linear tracer bias extracted from the large-scale auto-correlation function and expectations from theory, if sufficiently large voids are considered. For smaller voids we observe a shift towards higher values. This has important consequences on cosmological parameter inference, as the problem of unknown tracer bias is alleviated up to a constant number. The smallest scales in existing data sets become accessible to simpler models, providing numerous modes of the density field that have been disregarded so far, but may help to further reduce statistical errors in constraining cosmology.

Shape measurement biases from underfitting and ellipticity gradients

DOE PAGES

Bernstein, Gary M.

2010-08-21

With this study, precision weak gravitational lensing experiments require measurements of galaxy shapes accurate to <1 part in 1000. We investigate measurement biases, noted by Voigt and Bridle (2009) and Melchior et al. (2009), that are common to shape measurement methodologies that rely upon fitting elliptical-isophote galaxy models to observed data. The first bias arises when the true galaxy shapes do not match the models being fit. We show that this "underfitting bias" is due, at root, to these methods' attempts to use information at high spatial frequencies that has been destroyed by the convolution with the point-spread function (PSF)more » and/or by sampling. We propose a new shape-measurement technique that is explicitly confined to observable regions of k-space. A second bias arises for galaxies whose ellipticity varies with radius. For most shape-measurement methods, such galaxies are subject to "ellipticity gradient bias". We show how to reduce such biases by factors of 20–100 within the new shape-measurement method. The resulting shear estimator has multiplicative errors < 1 part in 10 3 for high-S/N images, even for highly asymmetric galaxies. Without any training or recalibration, the new method obtains Q = 3000 in the GREAT08 Challenge of blind shear reconstruction on low-noise galaxies, several times better than any previous method.« less

Free energy calculations: an efficient adaptive biasing potential method.

PubMed

Dickson, Bradley M; Legoll, Frédéric; Lelièvre, Tony; Stoltz, Gabriel; Fleurat-Lessard, Paul

2010-05-06

We develop an efficient sampling and free energy calculation technique within the adaptive biasing potential (ABP) framework. By mollifying the density of states we obtain an approximate free energy and an adaptive bias potential that is computed directly from the population along the coordinates of the free energy. Because of the mollifier, the bias potential is "nonlocal", and its gradient admits a simple analytic expression. A single observation of the reaction coordinate can thus be used to update the approximate free energy at every point within a neighborhood of the observation. This greatly reduces the equilibration time of the adaptive bias potential. This approximation introduces two parameters: strength of mollification and the zero of energy of the bias potential. While we observe that the approximate free energy is a very good estimate of the actual free energy for a large range of mollification strength, we demonstrate that the errors associated with the mollification may be removed via deconvolution. The zero of energy of the bias potential, which is easy to choose, influences the speed of convergence but not the limiting accuracy. This method is simple to apply to free energy or mean force computation in multiple dimensions and does not involve second derivatives of the reaction coordinates, matrix manipulations nor on-the-fly adaptation of parameters. For the alanine dipeptide test case, the new method is found to gain as much as a factor of 10 in efficiency as compared to two basic implementations of the adaptive biasing force methods, and it is shown to be as efficient as well-tempered metadynamics with the postprocess deconvolution giving a clear advantage to the mollified density of states method.

Investigating bias in squared regression structure coefficients

PubMed Central

Nimon, Kim F.; Zientek, Linda R.; Thompson, Bruce

2015-01-01

The importance of structure coefficients and analogs of regression weights for analysis within the general linear model (GLM) has been well-documented. The purpose of this study was to investigate bias in squared structure coefficients in the context of multiple regression and to determine if a formula that had been shown to correct for bias in squared Pearson correlation coefficients and coefficients of determination could be used to correct for bias in squared regression structure coefficients. Using data from a Monte Carlo simulation, this study found that squared regression structure coefficients corrected with Pratt's formula produced less biased estimates and might be more accurate and stable estimates of population squared regression structure coefficients than estimates with no such corrections. While our findings are in line with prior literature that identified multicollinearity as a predictor of bias in squared regression structure coefficients but not coefficients of determination, the findings from this study are unique in that the level of predictive power, number of predictors, and sample size were also observed to contribute bias in squared regression structure coefficients. PMID:26217273

Biases in Total Precipitable Water Vapor Climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer

NASA Technical Reports Server (NTRS)

Fetzer, Eric J.; Lambrigtsen, Bjorn H.; Eldering, Annmarie; Aumann, Hartmut H.; Chahine, Moustafa T.

2006-01-01

We examine differences in total precipitable water vapor (PWV) from the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Scanning Radiometer (AMSR-E) experiments sharing the Aqua spacecraft platform. Both systems provide estimates of PWV over water surfaces. We compare AIRS and AMSR-E PWV to constrain AIRS retrieval uncertainties as functions of AIRS retrieved infrared cloud fraction. PWV differences between the two instruments vary only weakly with infrared cloud fraction up to about 70%. Maps of AIRS-AMSR-E PWV differences vary with location and season. Observational biases, when both instruments observe identical scenes, are generally less than 5%. Exceptions are in cold air outbreaks where AIRS is biased moist by 10-20% or 10-60% (depending on retrieval processing) and at high latitudes in winter where AIRS is dry by 5-10%. Sampling biases, from different sampling characteristics of AIRS and AMSR-E, vary in sign and magnitude. AIRS sampling is dry by up to 30% in most high-latitude regions but moist by 5-15% in subtropical stratus cloud belts. Over the northwest Pacific, AIRS samples conditions more moist than AMSR-E by a much as 60%. We hypothesize that both wet and dry sampling biases are due to the effects of clouds on the AIRS retrieval methodology. The sign and magnitude of these biases depend upon the types of cloud present and on the relationship between clouds and PWV. These results for PWV imply that climatologies of height-resolved water vapor from AIRS must take into consideration local meteorological processes affecting AIRS sampling.

Unconscious mood-congruent memory bias in depression.

PubMed

Watkins, P C; Vache, K; Verney, S P; Muller, S; Mathews, A

1996-02-01

The purpose of this study was to investigate an unconscious or implicit mood-congruent memory (MCM) bias in clinical depression. Many studies have shown an explicit memory bias, but no study has yet found an implicit MCM bias in clinical depression. The authors compared depressed and control group participants on a conceptually driven implicit memory test. After studying words of positive, neutral, and negative affective valences, participants produced free associations to various cues. Implicit memory or priming was demonstrated by the production of more studied than unstudied words to the association cues. Depressed participants showed more priming of negative words, whereas controls showed more priming of positive words, thus supporting the MCM pattern. Also, no implicit memory deficit was found in depressed participants. These findings are discussed in the context of several prominent theories of cognition and depression.

Children's attractiveness, gender, and race biases: a comparison of their strength and generality.

PubMed

Rennels, Jennifer L; Langlois, Judith H

2014-01-01

Although research suggests that facial attractiveness biases significantly affect social development and interactions, these biases are understudied in the developmental literature and are overlooked when designing interventions relative to gender and race. The authors, therefore, compared how much bias 3- to 11-year-olds (N = 102) displayed in the three domains. They also examined whether bias and flexibility (understanding that different social groups can possess similar attributes) were related across domains. Children's attractiveness biases, particularly for girl targets, were as strong as or stronger than gender or race biases. Flexibility, but not bias, was related across domains. Developmental scientists and policy makers should increase efforts toward understanding development of attractiveness biases and determine which methods of teaching flexibility are most successful at reducing bias across domains. © 2014 The Authors. Child Development © 2014 Society for Research in Child Development, Inc.

Mood-congruent free recall bias in anxious individuals is not a consequence of response bias.

PubMed

Russo, Riccardo; Whittuck, Dora; Roberson, Debi; Dutton, Kevin; Georgiou, George; Fox, Elaine

2006-05-01

The status of mood-congruent free recall bias in anxious individuals was evaluated following incidental encoding of target words. Individuals with high and low levels of trait anxiety completed a modified Stroop task, which revealed an attentional bias for threat-related stimuli in anxious individuals. This group was significantly slower in naming the colour in which threat-related words were displayed compared to neutral words. In a subsequent free recall test for the words used in the modified Stroop task, anxious individuals recalled more threat-related words compared to low-anxious people. This difference was significant even when controlling for the false recall of items that had not been presented during study. These results support the view put forward by Russo, Fox, Bellinger, and Nguyen-Van-Tam (2001) that mood-congruent free recall bias in anxious individuals can be observed if the target material is encoded at a relatively shallow level. Moreover, contrary to Dowens and Calvo (2003), the current results show that the memory advantage for threat-related information in anxious individuals is not a consequence of response bias.

Mood-congruent free recall bias in anxious individuals is not a consequence of response bias

PubMed Central

Russo, Riccardo; Whittuck, Dora; Roberson, Debi; Dutton, Kevin; Georgiou, George; Fox, Elaine

2007-01-01

The status of mood-congruent free recall bias in anxious individuals was evaluated following incidental encoding of target words. Individuals with high and low levels of trait anxiety completed a modified Stroop task, which revealed an attentional bias for threat-related stimuli in anxious individuals. This group was significantly slower in naming the colour in which threat-related words were displayed compared to neutral words. In a subsequent free recall test for the words used in the modified Stroop task, anxious individuals recalled more threat-related words compared to low-anxious people. This difference was significant even when controlling for the false recall of items that had not been presented during study. These results support the view put forward by Russo, Fox, Bellinger, and Nguyen-Van-Tam (2001) that mood-congruent free recall bias in anxious individuals can be observed if the target material is encoded at a relatively shallow level. Moreover, contrary to Dowens and Calvo (2003), the current results show that the memory advantage for threat-related information in anxious individuals is not a consequence of response bias. PMID:16766443

Investigating d-cycloserine as a potential pharmacological enhancer of an emotional bias learning procedure.

PubMed

Woud, Marcella L; Blackwell, Simon E; Steudte-Schmiedgen, Susann; Browning, Michael; Holmes, Emily A; Harmer, Catherine J; Margraf, Jürgen; Reinecke, Andrea

2018-05-01

The partial N-methyl-D-aspartate receptor agonist d-cycloserine may enhance psychological therapies. However, its exact mechanism of action is still being investigated. Cognitive bias modification techniques allow isolation of cognitive processes and thus investigation of how they may be affected by d-cycloserine. We used a cognitive bias modification paradigm targeting appraisals of a stressful event, Cognitive Bias Modification-Appraisal, to investigate whether d-cycloserine enhanced the modification of appraisal, and whether it caused greater reduction in indices of psychopathology. Participants received either 250 mg of d-cycloserine ( n=19) or placebo ( n=19). As a stressor task, participants recalled a negative life event, followed by positive Cognitive Bias Modification-Appraisal training. Before and after Cognitive Bias Modification-Appraisal, appraisals and indices of psychopathology related to the stressor were assessed. Cognitive Bias Modification-Appraisal successfully modified appraisals, but d-cycloserine did not affect appraisals post-training. There were no post-training group differences in frequency of intrusions. Interestingly, d-cycloserine led to a greater reduction in distress and impact on state mood from recalling the event, and lower distress post-training was associated with fewer intrusions. Therefore, d-cycloserine may affect emotional reactivity to recalling a negative event when combined with induction of a positive appraisal style, but via a mechanism other than enhanced learning of the appraisal style.

Attention bias and anxiety in young children exposed to family violence.

PubMed

Briggs-Gowan, Margaret J; Pollak, Seth D; Grasso, Damión; Voss, Joel; Mian, Nicholas D; Zobel, Elvira; McCarthy, Kimberly J; Wakschlag, Lauren S; Pine, Daniel S

2015-11-01

Attention bias toward threat is associated with anxiety in older youth and adults and has been linked with violence exposure. Attention bias may moderate the relationship between violence exposure and anxiety in young children. Capitalizing on measurement advances, this study examines these relationships at a younger age than previously possible. Young children (mean age 4.7, ±0.8) from a cross-sectional sample oversampled for violence exposure (N = 218) completed the dot-probe task to assess their attention biases. Observed fear/anxiety was characterized with a novel observational paradigm, the Anxiety Dimensional Observation Scale. Mother-reported symptoms were assessed with the Preschool Age Psychiatric Assessment and Trauma Symptom Checklist for Young Children. Violence exposure was characterized with dimensional scores reflecting probability of membership in two classes derived via latent class analysis from the Conflict Tactics Scales: Abuse and Harsh Parenting. Family violence predicted greater child anxiety and trauma symptoms. Attention bias moderated the relationship between violence and anxiety. Attention bias toward threat may strengthen the effects of family violence on the development of anxiety, with potentially cascading effects across childhood. Such associations maybe most readily detected when using observational measures of childhood anxiety.

Biased Tests.

ERIC Educational Resources Information Center

Green, Donald Ross

This paper is concerned with the accusations made by such groups as the Association of Black Psychologists in their call for a moratorium on testing, that standardized tests are biased. A biased test measures one trait in one group of people but a different trait in a second group. Evidence about the amount of bias in tests is thin. Bias must be…

Approach bias modification in inpatient psychiatric smokers.

PubMed

Machulska, Alla; Zlomuzica, Armin; Rinck, Mike; Assion, Hans-Jörg; Margraf, Jürgen

2016-05-01

Drug-related automatic approach tendencies contribute to the development and maintenance of addictive behavior. The present study investigated whether a nicotine-related approach bias can be modified in smokers undergoing inpatient psychiatric treatment by using a novel training variant of the nicotine Approach-Avoidance-Task (AAT). Additionally, we assessed whether the AAT-training would affect smoking behavior. Inpatient smokers were randomly assigned to either an AAT-training or a sham-training condition. In the AAT-training condition, smokers were indirectly instructed to make avoidance movements in response to nicotine-related pictures and to make approach movements in response to tooth-cleaning pictures. In the sham-training condition, no contingency between picture content und arm movements existed. Trainings were administered in four sessions, accompanied by a brief smoking-cessation intervention. Smoking-related self-report measures and automatic approach biases toward smoking cues were measured before and after training. Three months after training, daily nicotine consumption was obtained. A total of 205 participants were recruited, and data from 139 participants were considered in the final analysis. Prior to the trainings, smokers in both conditions exhibited a stronger approach bias for nicotine-related pictures than for tooth-cleaning pictures. After both trainings, this difference was no longer evident. Although reduced smoking behavior at posttest was observed after both trainings, only the AAT-training led to a larger reduction of nicotine consumption at a three-month follow-up. Our preliminary data partially support the conclusion that the AAT might be a feasible tool to reduce smoking in the long-term in psychiatric patients, albeit its effect on other smoking-related measures remains to be explored. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spitzer Observations of GRB Hosts: A Legacy Approach

NASA Astrophysics Data System (ADS)

Perley, Daniel; Tanvir, Nial; Hjorth, Jens; Berger, Edo; Laskar, Tanmoy; Michalowski, Michal; Chary, Ranga-Ram; Fynbo, Johan; Levan, Andrew

2012-09-01

The host galaxies of long-duration GRBs are drawn from uniquely broad range of luminosities and redshifts. Thus they offer the possibility of studying the evolution of star-forming galaxies without the limitations of other luminosity-selected samples, which typically are increasingly biased towards the most massive systems at higher redshift. However, reaping the full benefits of this potential requires careful attention to the selection biases affecting host identification. To this end, we propose observations of a Legacy sample of 70 GRB host galaxies (an additional 70 have already been observed by Spitzer), in order to constrain the mass and luminosity function in GRB-selected galaxies at high redshift, including its dependence on redshift and on properties of the afterglow. Crucially, and unlike previous Spitzer surveys, this sample is carefully designed to be uniform and free of optical selection biases that have caused previous surveys to systematically under-represent the role of luminous, massive hosts. We also propose to extend to larger, more powerfully constraining samples the study of two science areas where Spitzer observations have recently shown spectacular success: the hosts of dust-obscured GRBs (which promise to further our understanding of the connection between GRBs and star-formation in the most luminous galaxies), and the evolution of the mass-metallicity relation at z>2 (for which GRB host observations provide particularly powerful constraints on high-z chemical evolution).

Applying quantitative bias analysis to estimate the plausible effects of selection bias in a cluster randomised controlled trial: secondary analysis of the Primary care Osteoarthritis Screening Trial (POST).

PubMed

Barnett, L A; Lewis, M; Mallen, C D; Peat, G

2017-12-04

Selection bias is a concern when designing cluster randomised controlled trials (c-RCT). Despite addressing potential issues at the design stage, bias cannot always be eradicated from a trial design. The application of bias analysis presents an important step forward in evaluating whether trial findings are credible. The aim of this paper is to give an example of the technique to quantify potential selection bias in c-RCTs. This analysis uses data from the Primary care Osteoarthritis Screening Trial (POST). The primary aim of this trial was to test whether screening for anxiety and depression, and providing appropriate care for patients consulting their GP with osteoarthritis would improve clinical outcomes. Quantitative bias analysis is a seldom-used technique that can quantify types of bias present in studies. Due to lack of information on the selection probability, probabilistic bias analysis with a range of triangular distributions was also used, applied at all three follow-up time points; 3, 6, and 12 months post consultation. A simple bias analysis was also applied to the study. Worse pain outcomes were observed among intervention participants than control participants (crude odds ratio at 3, 6, and 12 months: 1.30 (95% CI 1.01, 1.67), 1.39 (1.07, 1.80), and 1.17 (95% CI 0.90, 1.53), respectively). Probabilistic bias analysis suggested that the observed effect became statistically non-significant if the selection probability ratio was between 1.2 and 1.4. Selection probability ratios of > 1.8 were needed to mask a statistically significant benefit of the intervention. The use of probabilistic bias analysis in this c-RCT suggested that worse outcomes observed in the intervention arm could plausibly be attributed to selection bias. A very large degree of selection of bias was needed to mask a beneficial effect of intervention making this interpretation less plausible.

Deadly Attraction - Attentional Bias toward Preferred Cigarette Brand in Smokers.

PubMed

Domaradzka, Ewa; Bielecki, Maksymilian

2017-01-01

Numerous studies have shown that biases in visual attention might be evoked by affective and personally relevant stimuli, for example addiction-related objects. Despite the fact that addiction is often linked to specific products and systematic purchase behaviors, no studies focused directly on the existence of bias evoked by brands. Smokers are characterized by high levels of brand loyalty and everyday contact with cigarette packaging. Using the incentive-salience mechanism as a theoretical framework, we hypothesized that this group might exhibit a bias toward the preferred cigarette brand. In our study, a group of smokers ( N = 40) performed a dot probe task while their eye movements were recorded. In every trial a pair of pictures was presented - each of them showed a single cigarette pack. The visual properties of stimuli were carefully controlled, so branding information was the key factor affecting subjects' reactions. For each participant, we compared gaze behavior related to the preferred vs. other brands. The analyses revealed no attentional bias in the early, orienting phase of the stimulus processing and strong differences in maintenance and disengagement. Participants spent more time looking at the preferred cigarettes and saccades starting at the preferred brand location had longer latencies. In sum, our data shows that attentional bias toward brands might be found in situations not involving choice or decision making. These results provide important insights into the mechanisms of formation and maintenance of attentional biases to stimuli of personal relevance and might serve as a first step toward developing new attitude measurement techniques.

TYPE Ia SUPERNOVA DISTANCE MODULUS BIAS AND DISPERSION FROM K-CORRECTION ERRORS: A DIRECT MEASUREMENT USING LIGHT CURVE FITS TO OBSERVED SPECTRAL TIME SERIES

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

Saunders, C.; Aldering, G.; Aragon, C.

2015-02-10

We estimate systematic errors due to K-corrections in standard photometric analyses of high-redshift Type Ia supernovae. Errors due to K-correction occur when the spectral template model underlying the light curve fitter poorly represents the actual supernova spectral energy distribution, meaning that the distance modulus cannot be recovered accurately. In order to quantify this effect, synthetic photometry is performed on artificially redshifted spectrophotometric data from 119 low-redshift supernovae from the Nearby Supernova Factory, and the resulting light curves are fit with a conventional light curve fitter. We measure the variation in the standardized magnitude that would be fit for a givenmore » supernova if located at a range of redshifts and observed with various filter sets corresponding to current and future supernova surveys. We find significant variation in the measurements of the same supernovae placed at different redshifts regardless of filters used, which causes dispersion greater than ∼0.05 mag for measurements of photometry using the Sloan-like filters and a bias that corresponds to a 0.03 shift in w when applied to an outside data set. To test the result of a shift in supernova population or environment at higher redshifts, we repeat our calculations with the addition of a reweighting of the supernovae as a function of redshift and find that this strongly affects the results and would have repercussions for cosmology. We discuss possible methods to reduce the contribution of the K-correction bias and uncertainty.« less

Nutrition affects insect susceptibility to Bt toxins

NASA Astrophysics Data System (ADS)

Deans, Carrie A.; Behmer, Spencer T.; Tessnow, Ashley E.; Tamez-Guerra, Patricia; Pusztai-Carey, Marianne; Sword, Gregory A.

2017-01-01

Pesticide resistance represents a major challenge to global food production. The spread of resistance alleles is the primary explanation for observations of reduced pesticide efficacy over time, but the potential for gene-by-environment interactions (plasticity) to mediate susceptibility has largely been overlooked. Here we show that nutrition is an environmental factor that affects susceptibility to Bt toxins. Protein and carbohydrates are two key macronutrients for insect herbivores, and the polyphagous pest Helicoverpa zea self-selects and performs best on diets that are protein-biased relative to carbohydrates. Despite this, most Bt bioassays employ carbohydrate-biased rearing diets. This study explored the effect of diet protein-carbohydrate content on H. zea susceptibility to Cry1Ac, a common Bt endotoxin. We detected a 100-fold increase in LC50 for larvae on optimal versus carbohydrate-biased diets, and significant diet-mediated variation in survival and performance when challenged with Cry1Ac. Our results suggest that Bt resistance bioassays that use ecologically- and physiologically-mismatched diets over-estimate susceptibility and under-estimate resistance.

Incorporating affective bias in models of human decision making

NASA Technical Reports Server (NTRS)

Nygren, Thomas E.

1991-01-01

Research on human decision making has traditionally focused on how people actually make decisions, how good their decisions are, and how their decisions can be improved. Recent research suggests that this model is inadequate. Affective as well as cognitive components drive the way information about relevant outcomes and events is perceived, integrated, and used in the decision making process. The affective components include how the individual frames outcomes as good or bad, whether the individual anticipates regret in a decision situation, the affective mood state of the individual, and the psychological stress level anticipated or experienced in the decision situation. A focus of the current work has been to propose empirical studies that will attempt to examine in more detail the relationships between the latter two critical affective influences (mood state and stress) on decision making behavior.

Zero bias thermally stimulated currents in synthetic diamond

NASA Astrophysics Data System (ADS)

Mori, R.; Miglio, S.; Bruzzi, M.; Bogani, F.; De Sio, A.; Pace, E.

2009-06-01

Zero bias thermally stimulated currents (ZBTSCs) have been observed in single crystal high pressure high temperature (HPHT) and polycrystalline chemical vapor deposited (pCVD) diamond films. The ZBTSC technique is characterized by an increased sensitivity with respect to a standard TSC analysis. Due to the absence of the thermally activated background current, new TSC peaks have been observed in both HPHT and pCVD diamond films, related to shallow activation energies usually obscured by the emission of the dominant impurities. The ZBTSC peaks are explained in terms of defect discharge in the nonequilibrium potential distribution created by a nonuniform traps filling at the metal-diamond junctions. The electric field due to the charged defects has been estimated in a quasizero bias TSC experiment by applying an external bias.

Effects of Hot Limiter Biasing on Tokamak Runaway Discharges

NASA Astrophysics Data System (ADS)

Salar Elahi, A.; Ghoranneviss, M.; Ghanbari, M. R.

2013-10-01

In this research hot limiter biasing effects on the Runaway discharges were investigated. First wall of the tokamak reactors can affects serious damage due to the high energy runaway electrons during a major disruption and therefore its life time can be reduced. Therefore, it is important to find methods to decrease runaway electron generation and their energy. Tokamak limiter biasing is one of the methods for controlling the radial electric field and can induce a transition to an improved confinement state. In this article generation of runaway electrons and the energy they can obtain will be investigated theoretically. Moreover, in order to apply radial biasing an emissive limiter biasing is utilized. The biased limiter can apply +380 V in the status of cold and hot to the plasma and result in the increase of negative bias current in hot status. In fact, in this experiment we try to decrease the generation of runaway electrons and their energy by using emissive limiter biasing inserted on the IR-T1 tokamak. The mean energy of these electrons was obtained by spectroscopy of hard X-ray. Also, the plasma current center shift was measured from the vertical field coil characteristics in presence of limiter biasing. The calculation is made focusing on the vertical field coil current and voltage changes due to a horizontal displacement of plasma column.

Written threat: Electrophysiological evidence for an attention bias to affective words in social anxiety disorder.

PubMed

Wabnitz, Pascal; Martens, Ulla; Neuner, Frank

2016-01-01

Social anxiety disorder (SAD) is associated with heightened sensitivity to threat cues, typically represented by emotional facial expressions. To examine if this bias can be transferred to a general hypersensitivity or whether it is specific to disorder relevant cues, we investigated electrophysiological correlates of emotional word processing (alpha activity and event-related potentials) in 20 healthy participants and 20 participants with SAD. The experimental task was a silent reading of neutral, positive, physically threatening and socially threatening words (the latter were abusive swear words) while responding to a randomly presented dot. Subsequently, all participants were asked to recall as many words as possible during an unexpected recall test. Participants with SAD showed blunted sensory processing followed by a rapid processing of emotional words during early stages (early posterior negativity - EPN). At later stages, all participants showed enhanced processing of negative (physically and socially threatening) compared to neutral and positive words (N400). Moreover, at later processing stages alpha activity was increased specifically for negative words in participants with SAD but not in healthy controls. Recall of emotional words for all subjects was best for socially threatening words, followed by negative and positive words irrespective of social anxiety. The present findings indicate that SAD is associated with abnormalities in emotional word processing characterised by early hypervigilance to emotional cues followed by cognitive avoidance at later processing stages. Most importantly, the specificity of these attentional biases seems to change as a function of time with a general emotional bias at early and a more specific bias at later processing stages.

Neural signatures of cognitive and emotional biases in depression

PubMed Central

Fossati, Philippe

2008-01-01

Functional brain imaging studies suggest that depression is a system-level disorder affecting discrete but functionally linked cortical and limbic structures, with abnormalities in the anterior cingulate, lateral, ami medial prefrontal cortex, amygdala, ami hippocampus. Within this circuitry, abnormal corticolimbic interactions underlie cognitive deficits ami emotional impairment in depression. Depression involves biases toward processing negative emotional information and abnormal self-focus in response to emotional stimuli. These biases in depression could reflect excessive analytical self-focus in depression, as well as impaired cognitive control of emotional response to negative stimuli. By combining structural and functional investigations, brain imaging studies mav help to generate novel antidepressant treatments that regulate structural and factional plasticity within the neural network regulating mood and affective behavior.

A normality bias in legal decision making.

PubMed

Prentice, Robert A; Koehler, Jonathan J

2003-03-01

It is important to understand how legal fact finders determine causation and assign blame. However, this process is poorly understood. Among the psychological factors that affect decision makers are an omission bias (a tendency to blame actions more than inactions [omissions] for bad results), and a normality bias (a tendency to react more strongly to bad outcomes that spring from abnormal rather than normal circumstances). The omission and normality biases often reinforce one another when inaction preserves the normal state and when action creates an abnormal state. But what happens when these biases push in opposite directions as they would when inaction promotes an abnormal state or when action promotes a normal state? Which bias exerts the stronger influence on the judgments and behaviors of legal decision makers? The authors address this issue in two controlled experiments. One experiment involves medical malpractice and the other involves stockbroker negligence. They find that jurors pay much more attention to the normality of conditions than to whether those conditions arose through acts or omissions. Defendants who followed a nontraditional medical treatment regime or who chose a nontraditional stock portfolio received more blame and more punishment for bad outcomes than did defendants who obtained equally poor results after recommending a traditional medical regime or a traditional stock portfolio. Whether these recommendations entailed an action or an omission was essentially irrelevant. The Article concludes with a discussion of the implications of a robust normality bias for American jurisprudence.

Children’s Attractiveness, Gender, and Race Biases: A Comparison of Their Strength and Generality

PubMed Central

Rennels, Jennifer L.; Langlois, Judith H.

2013-01-01

Although research suggests that facial attractiveness biases significantly affect social development and interactions, these biases are understudied in the developmental literature and are overlooked when designing interventions relative to gender and race. The authors, therefore, compared how much bias 3–11-year-olds (N=102) displayed in the three domains. They also examined whether bias and flexibility (understanding that different social groups can possess similar attributes) were related across domains. Children’s attractiveness biases, particularly for girl targets, were as strong as or stronger than gender or race biases. Flexibility, but not bias, was related across domains. Developmental scientists and policymakers should increase efforts toward understanding development of attractiveness biases and determine which methods of teaching flexibility are most successful at reducing bias across domains. PMID:24673180

Physician Racial Bias and Word Use during Racially Discordant Medical Interactions.

PubMed

Hagiwara, Nao; Slatcher, Richard B; Eggly, Susan; Penner, Louis A

2017-04-01

Physician racial bias can negatively affect Black patients' reactions to racially discordant medical interactions, suggesting that racial bias is manifested in physicians' communication with their Black patients. However, little is known about how physician racial bias actually influences their communication during these interactions. This study investigated how non-Black physicians' racial bias is related to their word use during medical interactions with Black patients. One hundred and seventeen video-recorded racially discordant medical interactions from a larger study were transcribed and analyzed using Linguistic Inquiry and Word Count (LIWC) software. Physicians with higher levels of implicit racial bias used first-person plural pronouns and anxiety-related words more frequently than physicians with lower levels of implicit bias. There was also a trend for physicians with higher levels of explicit racial bias to use first-person singular pronouns more frequently than physicians with lower levels of explicit bias. These findings suggest that non-Black physicians with higher levels of implicit racial bias may tend to use more words that reflect social dominance (i.e., first-person plural pronouns) and anxiety when interacting with Black patients.

Physician Racial Bias and Word Use during Racially Discordant Medical Interactions

PubMed Central

Hagiwara, Nao; Slatcher, Richard B.; Eggly, Susan; Penner, Louis A.

2016-01-01

Physician racial bias can negatively affect Black patients’ reactions to racially discordant medical interactions, suggesting that racial bias is manifested in physicians’ communication with their Black patients. However, little is known about how physician racial bias actually influences their communication during these interactions. This study investigated how non-Black physicians’ racial bias is related to their word use during medical interactions with Black patients. One hundred and seventeen video-recorded racially discordant medical interactions from a larger study were transcribed and analyzed using Linguistic Inquiry and Word Count (LIWC) software. Physicians with higher levels of implicit racial bias used first-person plural pronouns and anxiety-related words more frequently than physicians with lower levels of implicit bias. There was also a trend for physicians with higher levels of explicit racial bias to use first-person singular pronouns more frequently than physicians with lower levels of explicit bias. These findings suggest that non-Black physicians with higher levels of implicit racial bias may tend to use more words that reflect social dominance (i.e., first-person plural pronouns) and anxiety when interacting with Black patients. PMID:27309596

Giant perpendicular exchange bias with antiferromagnetic MnN

NASA Astrophysics Data System (ADS)

Zilske, P.; Graulich, D.; Dunz, M.; Meinert, M.

2017-05-01

We investigated an out-of-plane exchange bias system that is based on the antiferromagnet MnN. Polycrystalline, highly textured film stacks of Ta/MnN/CoFeB/MgO/Ta were grown on SiOx by (reactive) magnetron sputtering and studied by x-ray diffraction and Kerr magnetometry. Nontrivial modifications of the exchange bias and the perpendicular magnetic anisotropy were observed as functions of both film thicknesses and field cooling temperatures. In optimized film stacks, a giant perpendicular exchange bias of 3600 Oe and a coercive field of 350 Oe were observed at room temperature. The effective interfacial exchange energy is estimated to be Jeff = 0.24 mJ/m2 and the effective uniaxial anisotropy constant of the antiferromagnet is Keff = 24 kJ/m3. The maximum effective perpendicular anisotropy field of the CoFeB layer is Hani = 3400 Oe. These values are larger than any previously reported values. These results possibly open a route to magnetically stable, exchange biased perpendicularly magnetized spin valves.

Handling the satellite inter-frequency biases in triple-frequency observations

NASA Astrophysics Data System (ADS)

Zhao, Lewen; Ye, Shirong; Song, Jia

2017-04-01

The new generation of GNSS satellites, including BDS, Galileo, modernized GPS, and GLONASS, transmit navigation sdata at more frequencies. Multi-frequency signals open new prospects for precise positioning, but satellite code and phase inter-frequency biases (IFB) induced by the third frequency need to be handled. Satellite code IFB can be corrected using products estimated by different strategies, the theoretical and numerical compatibility of these methods need to be proved. Furthermore, a new type of phase IFB, which changes with the relative sun-spacecraft-earth geometry, has been observed. It is necessary to investigate the cause and possible impacts of phase Time-variant IFB (TIFB). Therefore, we present systematic analysis to illustrate the relevancy between satellite clocks and phase TIFB, and compare the handling strategies of the code and phase IFB in triple-frequency positioning. First, the un-differenced L1/L2 satellite clock corrections considering the hardware delays are derived. And IFB induced by the dual-frequency satellite clocks to triple-frequency PPP model is detailed. The analysis shows that estimated satellite clocks actually contain the time-variant phase hardware delays, which can be compensated in L1/L2 ionosphere-free combinations. However, the time-variant hardware delays will lead to TIFB if the third frequency is used. Then, the methods used to correct the code and phase IFB are discussed. Standard point positioning (SPP) and precise point positioning (PPP) using BDS observations are carried out to validate the improvement of different IFB correction strategies. Experiments show that code IFB derived from DCB or geometry-free and ionosphere-free combination show an agreement of 0.3 ns for all satellites. Positioning results and error distribution with two different code IFB correcting strategies achieve similar tendency, which shows their substitutability. The original and wavelet filtered phase TIFB long-term series show significant

Location and color biases have different influences on selective attention.

PubMed

Fecteau, Jillian H; Korjoukov, Ilia; Roelfsema, Pieter R

2009-05-01

Are locations or colors more effective cues in biasing attention? We addressed this question with a visual search task that featured an associative priming manipulation. The observers indicated which target appeared in a search array. Unknown to them, one target appeared at the same location more often and a second target appeared in the same color more often. Both location and color biases facilitated performance, but location biases benefited the selection of all targets, whereas color biases only benefited the associated target letter. The generalized benefit of location biases suggests that locations are more effective cues to attention.

Tunable reverse-biased graphene/silicon heterojunction Schottky diode sensor.

PubMed

Singh, Amol; Uddin, Ahsan; Sudarshan, Tangali; Koley, Goutam

2014-04-24

A new chemical sensor based on reverse-biased graphene/Si heterojunction diode has been developed that exhibits extremely high bias-dependent molecular detection sensitivity and low operating power. The device takes advantage of graphene's atomically thin nature, which enables molecular adsorption on its surface to directly alter graphene/Si interface barrier height, thus affecting the junction current exponentially when operated in reverse bias and resulting in ultrahigh sensitivity. By operating the device in reverse bias, the work function of graphene, and hence the barrier height at the graphene/Si heterointerface, can be controlled by the bias magnitude, leading to a wide tunability of the molecular detection sensitivity. Such sensitivity control is also possible by carefully selecting the graphene/Si heterojunction Schottky barrier height. Compared to a conventional graphene amperometric sensor fabricated on the same chip, the proposed sensor demonstrated 13 times higher sensitivity for NO₂ and 3 times higher for NH₃ in ambient conditions, while consuming ∼500 times less power for same magnitude of applied voltage bias. The sensing mechanism based on heterojunction Schottky barrier height change has been confirmed using capacitance-voltage measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anticipatory versus reactive spatial attentional bias to threat.

PubMed

Gladwin, Thomas E; Möbius, Martin; McLoughlin, Shane; Tyndall, Ian

2018-05-10

Dot-probe or visual probe tasks (VPTs) are used extensively to measure attentional biases. A novel variant termed the cued VPT (cVPT) was developed to focus on the anticipatory component of attentional bias. This study aimed to establish an anticipatory attentional bias to threat using the cVPT and compare its split-half reliability with a typical dot-probe task. A total of 120 students performed the cVPT task and dot-probe tasks. Essentially, the cVPT uses cues that predict the location of pictorial threatening stimuli, but on trials on which probe stimuli are presented the pictures do not appear. Hence, actual presentation of emotional stimuli did not affect responses. The reliability of the cVPT was higher at most cue-stimulus intervals and was .56 overall. A clear anticipatory attentional bias was found. In conclusion, the cVPT may be of methodological and theoretical interest. Using visually neutral predictive cues may remove sources of noise that negatively impact reliability. Predictive cues are able to bias response selection, suggesting a role of predicted outcomes in automatic processes. © 2018 The British Psychological Society.

Hispanic nurses' experiences of bias in the workplace.

PubMed

Moceri, Joane T

2014-01-01

The continuing issue of health inequity for Hispanics highlights the importance of retaining Hispanic nurses in the workplace. This article describes the use of short answers such as "Describe the bias you experienced" and "If a patient refused care, what was the reason given?" to increase understandings about bias through the descriptions of Hispanic nurses. In this study, bias was defined as those implicit negative stereotypes and attitudes that negatively affect judgments about, evaluations of, and actions toward others. For this qualitative component of a descriptive study employing both qualitative and quantitative methods, 111 Hispanic nurses responded to open-ended questions about experiences of bias that were included with a survey tool and demographic questionnaire. Three themes emerged: being overlooked and undervalued, having to prove competency, and living with "only-ness." Respect was an overarching concept. The written descriptions of bias provided depth and understanding to the quantitative findings. Nurse leaders are well positioned to develop and implement strategies to more effectively support Hispanic nurses and to promote nonbiased interactions in the workplace. Retaining Hispanic nurses is a vital component to address issues of health inequity for Hispanic patients.

Verbal makes it positive, spatial makes it negative: working memory biases judgments, attention, and moods.

PubMed

Storbeck, Justin; Watson, Philip

2014-12-01

Prior research has suggested that emotion and working memory domains are integrated, such that positive affect enhances verbal working memory, whereas negative affect enhances spatial working memory (Gray, 2004; Storbeck, 2012). Simon (1967) postulated that one feature of emotion and cognition integration would be reciprocal connectedness (i.e., emotion influences cognition and cognition influences emotion). We explored whether affective judgments and attention to affective qualities are biased by the activation of verbal and spatial working memory mind-sets. For all experiments, participants completed a 2-back verbal or spatial working memory task followed by an endorsement task (Experiments 1 & 2), word-pair selection task (Exp. 3), or attentional dot-probe task (Exp. 4). Participants who had an activated verbal, compared with spatial, working memory mind-set were more likely to endorse pictures (Exp. 1) and words (Exp. 2) as being more positive and to select the more positive word pair out of a set of word pairs that went 'together best' (Exp. 3). Additionally, people who completed the verbal working memory task took longer to disengage from positive stimuli, whereas those who completed the spatial working memory task took longer to disengage from negative stimuli (Exp. 4). Interestingly, across the 4 experiments, we observed higher levels of self-reported negative affect for people who completed the spatial working memory task, which was consistent with their endorsement and attentional bias toward negative stimuli. Therefore, emotion and working memory may have a reciprocal connectedness allowing for bidirectional influence.

Developmental bias in cleavage-stage mouse blastomeres

PubMed Central

Tabansky, Inna; Lenarcic, Alan; Draft, Ryan W.; Loulier, Karine; Keskin, Derin B; Rosains, Jacqueline; Rivera-Feliciano, José; Lichtman, Jeff W.; Livet, Jean; Stern, Joel NH; Sanes, Joshua R.; Eggan, Kevin

2012-01-01

Summary Introduction The cleavage stage mouse embryo is composed of superficially equivalent blastomeres that will generate both the embryonic inner cell mass (ICM) and the supportive trophectoderm (TE). However, it remains unsettled whether the contribution of each blastomere to these two lineages can be accounted for by chance. Addressing the question of blastomere cell fate may be of practical importance, as preimplantation genetic diagnosis (PGD) requires removal of blastomeres from the early human embryo. To determine if blastomere allocation to the two earliest lineages is random, we developed and utilized a recombination-mediated, non-invasive combinatorial fluorescent labeling method for embryonic lineage tracing. Results When we induced recombination at cleavage stages, we observed a statistically significant bias in the contribution of the resulting labeled clones to the trophectoderm or the inner cell mass in a subset of embryos. Surprisingly, we did not find a correlation between localization of clones in the embryonic and abembryonic hemispheres of the late blastocyst and their allocation to the TE and ICM, suggesting that TE-ICM bias arises separately from embryonic-abembryonic bias. Rainbow lineage tracing also allowed us to demonstrate that the bias observed in the blastocyst persists into post-implantation stages, and therefore has relevance for subsequent development. Discussion The Rainbow transgenic mice that we describe here have allowed us to detect lineage-dependent bias in early development. They should also enable assessment of the developmental equivalence of mammalian progenitor cells in a variety of tissues. PMID:23177476

Spectral Resolution-linked Bias in Transit Spectroscopy of Extrasolar Planets

NASA Astrophysics Data System (ADS)

Deming, Drake; Sheppard, Kyle

2017-05-01

We re-visit the principles of transmission spectroscopy for transiting extrasolar planets, focusing on the overlap between the planetary spectrum and the illuminating stellar spectrum. Virtually all current models of exoplanetary transmission spectra utilize an approximation that is inaccurate when the spectrum of the illuminating star has a complex line structure, such as molecular bands in M-dwarf spectra. In those cases, it is desirable to model the observations using a coupled stellar-planetary radiative transfer model calculated at high spectral resolving power, followed by convolution to the observed resolution. Not consistently accounting for overlap of stellar M-dwarf and planetary lines at high spectral resolution can bias the modeled amplitude of the exoplanetary transmission spectrum, producing modeled absorption that is too strong. We illustrate this bias using the exoplanet TRAPPIST-1b, as observed using Hubble Space Telescope/WFC3. The bias in this case is about 250 ppm, 12% of the modeled transit absorption. Transit spectroscopy using JWST will have access to longer wavelengths where the water bands are intrinsically stronger, and the observed signal-to-noise ratios will be higher than currently possible. We therefore expect that this resolution-linked bias will be especially important for future JWST observations of TESS-discovered super-Earths and mini-Neptunes transiting M-dwarfs.

Science faculty's subtle gender biases favor male students.

PubMed

Moss-Racusin, Corinne A; Dovidio, John F; Brescoll, Victoria L; Graham, Mark J; Handelsman, Jo

2012-10-09

Despite efforts to recruit and retain more women, a stark gender disparity persists within academic science. Abundant research has demonstrated gender bias in many demographic groups, but has yet to experimentally investigate whether science faculty exhibit a bias against female students that could contribute to the gender disparity in academic science. In a randomized double-blind study (n = 127), science faculty from research-intensive universities rated the application materials of a student-who was randomly assigned either a male or female name-for a laboratory manager position. Faculty participants rated the male applicant as significantly more competent and hireable than the (identical) female applicant. These participants also selected a higher starting salary and offered more career mentoring to the male applicant. The gender of the faculty participants did not affect responses, such that female and male faculty were equally likely to exhibit bias against the female student. Mediation analyses indicated that the female student was less likely to be hired because she was viewed as less competent. We also assessed faculty participants' preexisting subtle bias against women using a standard instrument and found that preexisting subtle bias against women played a moderating role, such that subtle bias against women was associated with less support for the female student, but was unrelated to reactions to the male student. These results suggest that interventions addressing faculty gender bias might advance the goal of increasing the participation of women in science.

Enhanced spin wave propagation in magnonic rings by bias field modulation

NASA Astrophysics Data System (ADS)

Venkat, G.; Venkateswarlu, D.; Joshi, R. S.; Franchin, M.; Fangohr, H.; Anil Kumar, P. S.; Prabhakar, A.

2018-05-01

We simulate the spin wave (SW) dynamics in ring structures and obtain the ω - k dispersion relations corresponding to the output waveguide. Different bias field configurations affect the transfer of SW power from one arm of the structure to the other arm. To this end, we show that circular or radial bias fields are more suitable for energy transfer across the ring than the conventional horizontal bias field Hx. The SW dispersion shows that modes excited, when the bias field is along the ring radius, are almost 10 dB higher in power when compared to the modal power in the case of Hx. This is also corroborated by the SW energy density in the receiving stub.

An Exploration Based Cognitive Bias Test for Mice: Effects of Handling Method and Stereotypic Behaviour.

PubMed

Novak, Janja; Bailoo, Jeremy D; Melotti, Luca; Rommen, Jonas; Würbel, Hanno

2015-01-01

Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias). Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive bias test, using two different handling methods, as previous studies have shown that standard tail handling of mice increases physiological and behavioural measures of anxiety compared to cupped handling. Therefore, we hypothesised that tail handled mice would display a negative cognitive bias. We handled 28 female CD-1 mice for 16 weeks using either tail handling or cupped handling. The mice were then trained in an eight arm radial maze, where two adjacent arms predicted a positive outcome (darkness and food), while the two opposite arms predicted a negative outcome (no food, white noise and light). After six days of training, the mice were also given access to the four previously unavailable intermediate ambiguous arms of the radial maze and tested for cognitive bias. We were unable to validate this test, as mice from both handling groups displayed a similar pattern of exploration. Furthermore, we examined whether maze exploration is affected by the expression of stereotypic behaviour in the home cage. Mice with higher levels of stereotypic behaviour spent more time in positive arms and avoided ambiguous arms, displaying a negative cognitive bias. While this test needs further validation, our results indicate that it may allow the assessment of affective state in mice with minimal training-a major confound in current cognitive bias paradigms.

An Exploration Based Cognitive Bias Test for Mice: Effects of Handling Method and Stereotypic Behaviour

PubMed Central

Novak, Janja; Bailoo, Jeremy D.; Melotti, Luca; Rommen, Jonas; Würbel, Hanno

2015-01-01

Behavioural tests to assess affective states are widely used in human research and have recently been extended to animals. These tests assume that affective state influences cognitive processing, and that animals in a negative affective state interpret ambiguous information as expecting a negative outcome (displaying a negative cognitive bias). Most of these tests however, require long discrimination training. The aim of the study was to validate an exploration based cognitive bias test, using two different handling methods, as previous studies have shown that standard tail handling of mice increases physiological and behavioural measures of anxiety compared to cupped handling. Therefore, we hypothesised that tail handled mice would display a negative cognitive bias. We handled 28 female CD-1 mice for 16 weeks using either tail handling or cupped handling. The mice were then trained in an eight arm radial maze, where two adjacent arms predicted a positive outcome (darkness and food), while the two opposite arms predicted a negative outcome (no food, white noise and light). After six days of training, the mice were also given access to the four previously unavailable intermediate ambiguous arms of the radial maze and tested for cognitive bias. We were unable to validate this test, as mice from both handling groups displayed a similar pattern of exploration. Furthermore, we examined whether maze exploration is affected by the expression of stereotypic behaviour in the home cage. Mice with higher levels of stereotypic behaviour spent more time in positive arms and avoided ambiguous arms, displaying a negative cognitive bias. While this test needs further validation, our results indicate that it may allow the assessment of affective state in mice with minimal training—a major confound in current cognitive bias paradigms. PMID:26154309

Is there scale-dependent bias in single-field inflation?

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

De Putter, Roland; Doré, Olivier; Green, Daniel, E-mail: rdputter@caltech.edu, E-mail: Olivier.P.Dore@jpl.nasa.gov, E-mail: drgreen@cita.utoronto.ca

2015-10-01

Scale-dependent halo bias due to local primordial non-Gaussianity provides a strong test of single-field inflation. While it is universally understood that single-field inflation predicts negligible scale-dependent bias compared to current observational uncertainties, there is still disagreement on the exact level of scale-dependent bias at a level that could strongly impact inferences made from future surveys. In this paper, we clarify this confusion and derive in various ways that there is exactly zero scale-dependent bias in single-field inflation. Much of the current confusion follows from the fact that single-field inflation does predict a mode coupling of matter perturbations at the levelmore » of f{sub NL}{sup local}; ≈ −5/3, which naively would lead to scale-dependent bias. However, we show explicitly that this mode coupling cancels out when perturbations are evaluated at a fixed physical scale rather than fixed coordinate scale. Furthermore, we show how the absence of scale-dependent bias can be derived easily in any gauge. This result can then be incorporated into a complete description of the observed galaxy clustering, including the previously studied general relativistic terms, which are important at the same level as scale-dependent bias of order f{sub NL}{sup local} ∼ 1. This description will allow us to draw unbiased conclusions about inflation from future galaxy clustering data.« less

Dopamine receptor blockade attenuates the general incentive motivational effects of noncontingently delivered rewards and reward-paired cues without affecting their ability to bias action selection.

PubMed

Ostlund, Sean B; Maidment, Nigel T

2012-01-01

Environmental cues affect our behavior in a variety of ways. Despite playing an invaluable role in guiding our daily activities, such cues also appear to trigger the harmful, compulsive behaviors that characterize addiction and other disorders of behavioral control. In instrumental conditioning, rewards and reward-paired cues bias action selection and invigorate reward-seeking behaviors, and appear to do so through distinct neurobehavioral processes. Although reward-paired cues are known to invigorate performance through a dopamine-dependent incentive motivational process, it is not known if dopamine also mediates the influence of rewards and reward-paired cues over action selection. The current study contrasted the effects of systemic administration of the nonspecific dopamine receptor antagonist flupentixol on response invigoration and action bias in Pavlovian-instrumental transfer, a test of cue-elicited responding, and in instrumental reinstatement, a test of noncontingent reward-elicited responding. Hungry rats were trained on two different stimulus-outcome relationships (eg, tone-grain pellets and noise-sucrose solution) and two different action-outcome relationships (eg, left press-grain and right press-sucrose). At test, we found that flupentixol pretreatment blocked the response invigoration generated by the cues but spared their ability to bias action selection to favor the action whose outcome was signaled by the cue being presented. The response-biasing influence of noncontingent reward deliveries was also unaffected by flupentixol. Interestingly, although flupentixol had a modest effect on the immediate response invigoration produced by those rewards, it was particularly potent in countering the lingering enhancement of responding produced by multiple reward deliveries. These findings indicate that dopamine mediates the general incentive motivational effects of noncontingent rewards and reward-paired cues but does not support their ability to bias

Attention bias and anxiety in young children exposed to family violence

PubMed Central

Briggs-Gowan, Margaret J.; Pollak, Seth D.; Grasso, Damion; Voss, Joel; Mian, Nicholas D.; Zobel, Elvira; McCarthy, Kimberly J.; Wakschlag, Lauren S.; Pine, Daniel S.

2015-01-01

Background Attention bias towards threat is associated with anxiety in older youth and adults and has been linked with violence exposure. Attention bias may moderate the relationship between violence exposure and anxiety in young children. Capitalizing on measurement advances, the current study examines these relationships at a younger age than previously possible. Methods Young children (mean age 4.7, ±0.8) from a cross-sectional sample oversampled for violence exposure (N = 218) completed the dot-probe task to assess their attention biases. Observed fear/anxiety was characterized with a novel observational paradigm, the Anxiety Diagnostic Observation Schedule. Mother-reported symptoms were assessed with the Preschool-Age Psychiatric Assessment and Trauma Symptom Checklist for Young Children. Violence exposure was characterized with dimensional scores reflecting probability of membership in two classes derived via latent class analysis from the Conflict Tactics Scales: Abuse and Harsh Parenting. Results Family violence predicted greater child anxiety and trauma symptoms. Attention bias moderated the relationship between violence and anxiety. Conclusions Attention bias towards threat may strengthen the effects of family violence on the development of anxiety, with potentially cascading effects across childhood. Such associations may be most readily detected when using observational measures of childhood anxiety. PMID:26716142

Social desirability bias in dietary self-report may compromise the validity of dietary intake measures.

PubMed

Hebert, J R; Clemow, L; Pbert, L; Ockene, I S; Ockene, J K

1995-04-01

Self-report of dietary intake could be biased by social desirability or social approval thus affecting risk estimates in epidemiological studies. These constructs produce response set biases, which are evident when testing in domains characterized by easily recognizable correct or desirable responses. Given the social and psychological value ascribed to diet, assessment methodologies used most commonly in epidemiological studies are particularly vulnerable to these biases. Social desirability and social approval biases were tested by comparing nutrient scores derived from multiple 24-hour diet recalls (24HR) on seven randomly assigned days with those from two 7-day diet recalls (7DDR) (similar in some respects to commonly used food frequency questionnaires), one administered at the beginning of the test period (pre) and one at the end (post). Statistical analysis included correlation and multiple linear regression. Cross-sectionally, no relationships between social approval score and the nutritional variables existed. Social desirability score was negatively correlated with most nutritional variables. In linear regression analysis, social desirability score produced a large downward bias in nutrient estimation in the 7DDR relative to the 24HR. For total energy, this bias equalled about 50 kcal/point on the social desirability scale or about 450 kcal over its interquartile range. The bias was approximately twice as large for women as for men and only about half as large in the post measures. Individuals having the highest 24HR-derived fat and total energy intake scores had the largest downward bias due to social desirability. We observed a large downward bias in reporting food intake related to social desirability score. These results are consistent with the theoretical constructs on which the hypothesis is based. The effect of social desirability bias is discussed in terms of its influence on epidemiological estimates of effect. Suggestions are made for future work

Sympathetic bias.

PubMed

Levy, David M; Peart, Sandra J

2008-06-01

We wish to deal with investigator bias in a statistical context. We sketch how a textbook solution to the problem of "outliers" which avoids one sort of investigator bias, creates the temptation for another sort. We write down a model of the approbation seeking statistician who is tempted by sympathy for client to violate the disciplinary standards. We give a simple account of one context in which we might expect investigator bias to flourish. Finally, we offer tentative suggestions to deal with the problem of investigator bias which follow from our account. As we have given a very sparse and stylized account of investigator bias, we ask what might be done to overcome this limitation.

Cognitive-Processing Bias in Chinese Student Teachers with Strong and Weak Professional Identity.

PubMed

Wang, Xin-Qiang; Zhu, Jun-Cheng; Liu, Lu; Chen, Xiang-Yu

2017-01-01

Professional identity plays an important role in career development. Although many studies have examined professional identity, differences in cognitive-processing biases between Chinese student teachers with strong and weak professional identity are poorly understood. The current study adopted Tversky's social-cognitive experimental paradigm to explore cognitive-processing biases in Chinese student teachers with strong and weak professional identity. Experiment 1 showed that participants with strong professional identity exhibited stronger positive-coding bias toward positive profession-related life events, relative to that observed in those with weak professional identity. Experiment 2 showed that participants with strong professional identity exhibited greater recognition bias for previously read items, relative to that observed in those with weak professional identity. Overall, the results suggested that participants with strong professional identity exhibited greater positive cognitive-processing bias relative to that observed in those with weak professional identity.

Controllable exchange bias in Fe/metamagnetic FeRh bilayers

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

Suzuki, Ippei; Hamasaki, Yosuke; Itoh, Mitsuru

2014-10-27

We report the studies of tuning the exchange bias at ferromagnetic Fe/metamagnetic FeRh bilayer interfaces. Fe/FeRh(111) bilayers show exchange bias in the antiferromagnetic state of FeRh while no exchange bias occurs at Fe/FeRh(001) interface. The contrasting results are attributed to the spin configurations of FeRh at the interface, i.e., the uncompensated ferromagnetic spin configuration of FeRh appears exclusively for (111) orientation. The exchange bias disappears as the bilayers are warmed above the antiferromagnetic-ferromagnetic transition temperature. The direction of the exchange bias for Fe/FeRh(111) is also found to be perpendicular to the cooling-field direction, in contrast to the commonly observed directionmore » of exchange bias for ferromagnetic/antiferromagnetic interfaces. In view of these results, the exchange bias in Fe/FeRh bilayers with the (111) crystallographic orientation should be useful for the design of rapid writing technology for magnetic information devices.« less

Postdeployment threat-related attention bias interacts with combat exposure to account for PTSD and anxiety symptoms in soldiers.

PubMed

Sipos, Maurice L; Bar-Haim, Yair; Abend, Rany; Adler, Amy B; Bliese, Paul D

2014-02-01

Recent studies suggest that assessment of threat-related attention bias may be useful in identifying soldiers at risk for clinical symptoms. The present study assessed the degree to which soldiers experienced combat events and showed attentional threat avoidance affected their reported levels of post-traumatic stress disorder (PTSD) and anxiety symptoms. Four months after a combat deployment to Iraq, 63 US soldiers completed a survey assessing combat exposures and clinical symptoms as well as a dot-probe task assessing threat-related attention bias. Significant three-way interactions regressing threat reaction times (RTs), neutral RTs, and combat exposure on PTSD and anxiety symptoms were observed. Specifically, soldiers with high levels of combat exposure, who were more likely to demonstrate attentional bias away from threat, were also more symptomatic. These results demonstrate the potential of threat-related attention bias as a behavioral marker of PTSD and anxiety symptoms in a high-risk military occupational context. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Bias, belief, and consensus: Collective opinion formation on fluctuating networks

NASA Astrophysics Data System (ADS)

Ngampruetikorn, Vudtiwat; Stephens, Greg J.

2016-11-01

With the advent of online networks, societies have become substantially more interconnected with individual members able to easily both maintain and modify their own social links. Here, we show that active network maintenance exposes agents to confirmation bias, the tendency to confirm one's beliefs, and we explore how this bias affects collective opinion formation. We introduce a model of binary opinion dynamics on a complex, fluctuating network with stochastic rewiring and we analyze these dynamics in the mean-field limit of large networks and fast link rewiring. We show that confirmation bias induces a segregation of individuals with different opinions and stabilizes the consensus state. We further show that bias can have an unusual, nonmonotonic effect on the time to consensus and this suggests a novel avenue for large-scale opinion manipulation.

Evidence against mood-congruent attentional bias in Major Depressive Disorder.

PubMed

Cheng, Philip; Preston, Stephanie D; Jonides, John; Mohr, Alicia Hofelich; Thummala, Kirti; Casement, Melynda; Hsing, Courtney; Deldin, Patricia J

2015-12-15

Depression is consistently associated with biased retrieval and interpretation of affective stimuli, but evidence for depressive bias in earlier cognitive processing, such as attention, is mixed. In five separate experiments, individuals with depression (three experiments with clinically diagnosed major depression, two experiments with dysphoria measured via the Beck Depression Inventory) completed three tasks designed to elicit depressive biases in attention, including selective attention, attentional switching, and attentional inhibition. Selective attention was measured using a modified emotional Stroop task, while attentional switching and inhibition was examined via an emotional task-switching paradigm and an emotional counter task. Results across five different experiments indicate that individuals with depression perform comparably with healthy controls, providing corroboration that depression is not characterized by biases in attentional processes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Bias, belief, and consensus: Collective opinion formation on fluctuating networks.

PubMed

Ngampruetikorn, Vudtiwat; Stephens, Greg J

2016-11-01

With the advent of online networks, societies have become substantially more interconnected with individual members able to easily both maintain and modify their own social links. Here, we show that active network maintenance exposes agents to confirmation bias, the tendency to confirm one's beliefs, and we explore how this bias affects collective opinion formation. We introduce a model of binary opinion dynamics on a complex, fluctuating network with stochastic rewiring and we analyze these dynamics in the mean-field limit of large networks and fast link rewiring. We show that confirmation bias induces a segregation of individuals with different opinions and stabilizes the consensus state. We further show that bias can have an unusual, nonmonotonic effect on the time to consensus and this suggests a novel avenue for large-scale opinion manipulation.

Exploring cognitive bias in destination therapy left ventricular assist device decision making: A retrospective qualitative framework analysis.

PubMed

Magid, Molly; McIlvennan, Colleen K; Jones, Jaqueline; Nowels, Carolyn T; Allen, Larry A; Thompson, Jocelyn S; Matlock, Dan

2016-10-01

Cognitive biases are psychological influences, which cause humans to make decisions, which do not seemingly maximize utility. For people with heart failure, the left ventricular assist device (LVAD) is a surgically implantable device with complex tradeoffs. As such, it represents an excellent model within which to explore cognitive bias in a real-world decision. We conducted a framework analysis to examine for evidence of cognitive bias among people deciding whether or not to get an LVAD. The aim of this study was to explore the influence of cognitive bias on the LVAD decision-making process. We analyzed previously conducted interviews of patients who had either accepted or declined an LVAD using a deductive, predetermined framework of cognitive biases. We coded and analyzed the interviews using an inductive-deductive framework approach, which also allowed for other themes to emerge. We interviewed a total of 22 heart failure patients who had gone through destination therapy LVAD decision making (15 who had accepted the LVAD and 7 who had declined). All patients appeared influenced by state dependence, where both groups described high current state of suffering, but the groups differed in whether they believed LVAD would relieve suffering or not. We found evidence of cognitive bias that appeared to influence decision making in both patient groups, but groups differed in terms of which cognitive biases were present. Among accepters, we found evidence of anchoring bias, availability bias, optimism bias, and affective forecasting. Among decliners, we found evidence of errors in affective forecasting. Medical decision making is often a complicated and multifaceted process that includes cognitive bias as well as other influences. It is important for clinicians to recognize that patients can be affected by cognitive bias, so they can better understand and improve the decision-making process to ensure that patients are fully informed. Published by Elsevier Inc.

Observation of giant exchange bias in bulk Mn50Ni42Sn8 Heusler alloy

NASA Astrophysics Data System (ADS)

Sharma, Jyoti; Suresh, K. G.

2015-02-01

We report a giant exchange bias (EB) field of 3520 Oe in bulk Mn50Ni42Sn8 Heusler alloy. The low temperature magnetic state of the martensite phase has been studied by DC magnetization and AC susceptibility measurements. Frequency dependence of spin freezing temperature (Tf) on critical slowing down relation and observation of memory effect in zero field cooling mode confirms the super spin glass (SSG) phase at low temperatures. Large EB is attributed to the strong exchange coupling between the SSG clusters formed by small regions of ferromagnetic order embedded in an antiferromagnetic (AFM) matrix. The temperature and cooling field dependence of EB have been studied and related to the change in unidirectional anisotropy at SSG/AFM interface. The training effect also corroborates with the presence of frozen (SSG) moments at the interface and their role in EB.

Model for Codon Position Bias in RNA Editing

NASA Astrophysics Data System (ADS)

Liu, Tsunglin; Bundschuh, Ralf

2005-08-01

RNA editing can be crucial for the expression of genetic information via inserting, deleting, or substituting a few nucleotides at specific positions in an RNA sequence. Within coding regions in an RNA sequence, editing usually occurs with a certain bias in choosing the positions of the editing sites. In the mitochondrial genes of Physarum polycephalum, many more editing events have been observed at the third codon position than at the first and second, while in some plant mitochondria the second codon position dominates. Here we propose an evolutionary model that explains this bias as the basis of selection at the protein level. The model predicts a distribution of the three positions rather close to the experimental observation in Physarum. This suggests that the codon position bias in Physarum is mainly a consequence of selection at the protein level.

Publication Bias in Meta-Analyses of the Efficacy of Psychotherapeutic Interventions for Depression

ERIC Educational Resources Information Center

Niemeyer, Helen; Musch, Jochen; Pietrowsky, Reinhard

2013-01-01

Objective: The aim of this study was to assess whether systematic reviews investigating psychotherapeutic interventions for depression are affected by publication bias. Only homogeneous data sets were included, as heterogeneous data sets can distort statistical tests of publication bias. Method: We applied Begg and Mazumdar's adjusted rank…

Suppression of turbulent particle flux during biased rotation in LAPD

NASA Astrophysics Data System (ADS)

Carter, T. A.

2005-10-01

The edge plasma in LAPD is rotated through the application of a bias voltage (typically 100V-200V) between the plasma source cathode and the vacuum vessel wall. Without bias, cross-field turbulent particle transport causes the density profile to extend well past the cathode edge, with a fairly gentle gradient (Ln˜10 cm). As the bias voltage is applied and increased past a threshold value, the measured density profile steepens dramatically (Ln˜2 cm) at a radius near the peak of the flow shear. Turbulent transport flux measurements in this region show that the flux is reduced and then suppressed completely as the threshold is approached. As the bias voltage is increased further, the measured turbulent transport flux reverses direction. The amplitude of the density and azimuthal electric field fluctuations is observed to decrease during biased rotation, the product of the amplitudes decreasing by a factor of 5. However the dominant change appears in the cross-phase, which is altered dramatically, leading to the observed suppression and reversal of the turbulent flux. Detailed two-dimensional turbulent correlation measurements have been performed using the high repetition rate (1 Hz) and high reproducibility of LAPD plasmas. In unbiased plasmas, the correlation is localized to around 5 cm radially and a slightly smaller distance azimuthally (ρs˜0.5-1 cm). During biased rotation, a dramatic increase in the azimuthal correlation is observed, however there is little change in the radial correlation length.

Attention Bias Modification for Major Depressive Disorder: Effects on Attention Bias, Resting State Connectivity, and Symptom Change

PubMed Central

Beevers, Christopher G.; Clasen, Peter C.; Enock, Philip M.; Schnyer, David M.

2015-01-01

Cognitive theories of depression posit that selective attention for negative information contributes to the maintenance of depression. The current study experimentally tested this idea by randomly assigning adults with Major Depressive Disorder (MDD) to four weeks of computer-based attention bias modification designed to reduce negative attention bias or four weeks of placebo attention training. Findings indicate that compared to placebo training, attention bias modification reduced negative attention bias and increased resting-state connectivity within a neural circuit (i.e., middle frontal gyrus and dorsal anterior cingulate cortex) that supports control over emotional information. Further, pre- to post-training change in negative attention bias was significantly correlated with depression symptom change only in the active training condition. Exploratory analyses indicated that pre- to post-training changes in resting state connectivity within a circuit associated with sustained attention to visual information (i.e., precuenus and middle frontal gyrus) contributed to symptom improvement in the placebo condition. Importantly, depression symptoms did not change differentially between the training groups—overall, a 40% decrease in symptoms was observed across attention training conditions. Findings suggest that negative attention bias is associated with the maintenance of depression; however, general attentional control may also maintain depression symptoms, as evidenced by resting state connectivity and depression symptom improvement in the placebo training condition. PMID:25894440

The SDT Model of Belief Bias: Complexity, Time, and Cognitive Ability Mediate the Effects of Believability

ERIC Educational Resources Information Center

Trippas, Dries; Handley, Simon J.; Verde, Michael F.

2013-01-01

When people evaluate conclusions, they are often influenced by prior beliefs. Prevalent theories claim that "belief bias" affects the quality of syllogistic reasoning. However, recent work by Dube, Rotello, and Heit (2010) has suggested that belief bias may be a simple response bias. In Experiment 1, receiver operating characteristic…

Dependence of Halo Bias and Kinematics on Assembly Variables

NASA Astrophysics Data System (ADS)

Xu, Xiaoju; Zheng, Zheng

2018-06-01

Using dark matter haloes identified in a large N-body simulation, we study halo assembly bias, with halo formation time, peak maximum circular velocity, concentration, and spin as the assembly variables. Instead of grouping haloes at fixed mass into different percentiles of each assembly variable, we present the joint dependence of halo bias on the values of halo mass and each assembly variable. In the plane of halo mass and one assembly variable, the joint dependence can be largely described as halo bias increasing outward from a global minimum. We find it unlikely to have a combination of halo variables to absorb all assembly bias effects. We then present the joint dependence of halo bias on two assembly variables at fixed halo mass. The gradient of halo bias does not necessarily follow the correlation direction of the two assembly variables and it varies with halo mass. Therefore in general for two correlated assembly variables one cannot be used as a proxy for the other in predicting halo assembly bias trend. Finally, halo assembly is found to affect the kinematics of haloes. Low-mass haloes formed earlier can have much higher pairwise velocity dispersion than those of massive haloes. In general, halo assembly leads to a correlation between halo bias and halo pairwise velocity distribution, with more strongly clustered haloes having higher pairwise velocity and velocity dispersion. However, the correlation is not tight, and the kinematics of haloes at fixed halo bias still depends on halo mass and assembly variables.

Surface Winds and Dust Biases in Climate Models

NASA Astrophysics Data System (ADS)

Evan, A. T.

2018-01-01

An analysis of North African dust from models participating in the Fifth Climate Models Intercomparison Project (CMIP5) suggested that, when forced by observed sea surface temperatures, these models were unable to reproduce any aspects of the observed year-to-year variability in dust from North Africa. Consequently, there would be little reason to have confidence in the models' projections of changes in dust over the 21st century. However, no subsequent study has elucidated the root causes of the disagreement between CMIP5 and observed dust. Here I develop an idealized model of dust emission and then use this model to show that, over North Africa, such biases in CMIP5 models are due to errors in the surface wind fields and not due to the representation of dust emission processes. These results also suggest that because the surface wind field over North Africa is highly spatially autocorrelated, intermodel differences in the spatial structure of dust emission have little effect on the relative change in year-to-year dust emission over the continent. I use these results to show that similar biases in North African dust from the NASA Modern Era Retrospective analysis for Research and Applications (MERRA) version 2 surface wind field biases but that these wind biases were not present in the first version of MERRA.

Impact of tropical Atlantic sea-surface temperature biases on the simulated atmospheric circulation and precipitation over the Atlantic region: An ECHAM6 model study

NASA Astrophysics Data System (ADS)

Eichhorn, Astrid; Bader, Jürgen

2017-09-01

As many coupled atmosphere-ocean general circulation models, the coupled Earth System Model developed at the Max Planck Institute for Meteorology suffers from severe sea-surface temperature (SST) biases in the tropical Atlantic. We performed a set of SST sensitivity experiments with its atmospheric model component ECHAM6 to understand the impact of tropical Atlantic SST biases on atmospheric circulation and precipitation. The model was forced by a climatology of observed global SSTs to focus on simulated seasonal and annual mean state climate. Through the superposition of varying tropical Atlantic bias patterns extracted from the MPI-ESM on top of the control field, this study investigates the relevance of the seasonal variation and spatial structure of tropical Atlantic biases for the simulated response. Results show that the position and structure of the Intertropical Convergence Zone (ITCZ) across the Atlantic is significantly affected, exhibiting a dynamically forced shift of annual mean precipitation maximum to the east of the Atlantic basin as well as a southward shift of the oceanic rain belt. The SST-induced changes in the ITCZ in turn affect seasonal rainfall over adjacent continents. However not only the ITCZ position but also other effects arising from biases in tropical Atlantic SSTs, e.g. variations in the wind field, change the simulation of precipitation over land. The seasonal variation and spatial pattern of tropical Atlantic SST biases turns out to be crucial for the simulated atmospheric response and is essential for analyzing the contribution of SST biases to coupled model mean state biases. Our experiments show that MPI-ESM mean-state biases in the Atlantic sector are mainly driven by SST biases in the tropical Atlantic while teleconnections from other basins seem to play a minor role.

Effects of salience-network-node neurofeedback training on affective biases in major depressive disorder.

PubMed

Hamilton, J Paul; Glover, Gary H; Bagarinao, Epifanio; Chang, Catie; Mackey, Sean; Sacchet, Matthew D; Gotlib, Ian H

2016-03-30

Neural models of major depressive disorder (MDD) posit that over-response of components of the brain's salience network (SN) to negative stimuli plays a crucial role in the pathophysiology of MDD. In the present proof-of-concept study, we tested this formulation directly by examining the affective consequences of training depressed persons to down-regulate response of SN nodes to negative material. Ten participants in the real neurofeedback group saw, and attempted to learn to down-regulate, activity from an empirically identified node of the SN. Ten other participants engaged in an equivalent procedure with the exception that they saw SN-node neurofeedback indices from participants in the real neurofeedback group. Before and after scanning, all participants completed tasks assessing emotional responses to negative scenes and to negative and positive self-descriptive adjectives. Compared to participants in the sham-neurofeedback group, from pre- to post-training, participants in the real-neurofeedback group showed a greater decrease in SN-node response to negative stimuli, a greater decrease in self-reported emotional response to negative scenes, and a greater decrease in self-reported emotional response to negative self-descriptive adjectives. Our findings provide support for a neural formulation in which the SN plays a primary role in contributing to negative cognitive biases in MDD. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

When being narrow minded is a good thing: locally biased people show stronger contextual cueing.

PubMed

Bellaera, Lauren; von Mühlenen, Adrian; Watson, Derrick G

2014-01-01

Repeated contexts allow us to find relevant information more easily. Learning such contexts has been proposed to depend upon either global processing of the repeated contexts, or alternatively processing of the local region surrounding the target information. In this study, we measured the extent to which observers were by default biased to process towards a more global or local level. The findings showed that the ability to use context to help guide their search was strongly related to an observer's local/global processing bias. Locally biased people could use context to help improve their search better than globally biased people. The results suggest that the extent to which context can be used depends crucially on the observer's attentional bias and thus also to factors and influences that can change this bias.

Prior probability and feature predictability interactively bias perceptual decisions

PubMed Central

Dunovan, Kyle E.; Tremel, Joshua J.; Wheeler, Mark E.

2014-01-01

Anticipating a forthcoming sensory experience facilitates perception for expected stimuli but also hinders perception for less likely alternatives. Recent neuroimaging studies suggest that expectation biases arise from feature-level predictions that enhance early sensory representations and facilitate evidence accumulation for contextually probable stimuli while suppressing alternatives. Reasonably then, the extent to which prior knowledge biases subsequent sensory processing should depend on the precision of expectations at the feature level as well as the degree to which expected features match those of an observed stimulus. In the present study we investigated how these two sources of uncertainty modulated pre- and post-stimulus bias mechanisms in the drift-diffusion model during a probabilistic face/house discrimination task. We tested several plausible models of choice bias, concluding that predictive cues led to a bias in both the starting-point and rate of evidence accumulation favoring the more probable stimulus category. We further tested the hypotheses that prior bias in the starting-point was conditional on the feature-level uncertainty of category expectations and that dynamic bias in the drift-rate was modulated by the match between expected and observed stimulus features. Starting-point estimates suggested that subjects formed a constant prior bias in favor of the face category, which exhibits less feature-level variability, that was strengthened or weakened by trial-wise predictive cues. Furthermore, we found that the gain on face/house evidence was increased for stimuli with less ambiguous features and that this relationship was enhanced by valid category expectations. These findings offer new evidence that bridges psychological models of decision-making with recent predictive coding theories of perception. PMID:24978303

Experimental and theoretical determination of sea-state bias in radar altimetry

NASA Technical Reports Server (NTRS)

Stewart, Robert H.

1991-01-01

The major unknown error in radar altimetry is due to waves on the sea surface which cause the mean radar-reflecting surface to be displaced from mean sea level. This is the electromagnetic bias. The primary motivation for the project was to understand the causes of the bias so that the error it produces in radar altimetry could be calculated and removed from altimeter measurements made from space by the Topex/Poseidon altimetric satellite. The goals of the project were: (1) observe radar scatter at vertical incidence using a simple radar on a platform for a wide variety of environmental conditions at the same time wind and wave conditions were measured; (2) calculate electromagnetic bias from the radar observations; (3) investigate the limitations of the present theory describing radar scatter at vertical incidence; (4) compare measured electromagnetic bias with bias calculated from theory using measurements of wind and waves made at the time of the radar measurements; and (5) if possible, extend the theory so bias can be calculated for a wider range of environmental conditions.