scholarly journals Acquisition of visual priors and induced hallucinations in chronic schizophrenia

2018 ◽  
Author(s):  
Vincent Valton ◽  
Povilas Karvelis ◽  
Katie L. Richards ◽  
Aaron R. Seitz ◽  
Stephen M. Lawrie ◽  
...  
Keyword(s):  
Statistical Learning ◽  
Antipsychotic Medication ◽  
Chronic Schizophrenia ◽  
Learning Task ◽  
Detection Task ◽  
Estimation Task ◽  
Learning Deficits ◽  
The World ◽  
Sensory Evidence ◽  
Perceptual Threshold

AbstractProminent theories suggest that symptoms of schizophrenia stem from learning deficiencies resulting in distorted internal models of the world. To further test these theories, we here use a visual statistical learning task known to induce rapid implicit learning of the stimulus statistics (Chalk et al., 2010). In this task, participants are presented with a field of coherently moving dots and need to report the presented direction of the dots (estimation task) and whether they saw any dots or not (detection task). Two of the directions were more frequently presented than the others. In controls, the implicit acquisition of the stimuli statistics influences their perception in two ways: 1-motion directions are perceived as being more similar to the most frequently presented directions than they really are (estimation biases); 2-in the absence of stimuli, participants sometimes report perceiving the most frequently presented directions (a form of hallucinations). Such behaviour is consistent with probabilistic inference, i.e. combining learnt perceptual priors with sensory evidence. We investigated whether patients with chronic, stable, treated schizophrenia (n=20) differ from controls (n=23) in the acquisition of the perceptual priors and/or their influence on perception. We found that, although patients were slower than controls, they showed comparable acquisition of perceptual priors, correctly approximating the stimulus statistics. This suggests that patients have no statistical learning deficits in our task. This may reflect our patients relative wellbeing on antipsychotic medication. Intriguingly, however, patients made significantly fewer hallucinations of the most frequently presented directions than controls and fewer prior-based lapse estimations. This suggests that prior expectations had less influence on patients’ perception than on controls when stimuli were absent or below perceptual threshold.

scholarly journals Acquisition of visual priors and induced hallucinations in chronic schizophrenia

Brain ◽  
2019 ◽  
Vol 142 (8) ◽  
pp. 2523-2537 ◽  
Author(s):  
Vincent Valton ◽  
Povilas Karvelis ◽  
Katie L Richards ◽  
Aaron R Seitz ◽  
Stephen M Lawrie ◽  
...  
Keyword(s):  
Statistical Learning ◽  
Antipsychotic Medication ◽  
Chronic Schizophrenia ◽  
Learning Task ◽  
Detection Task ◽  
Estimation Task ◽  
Learning Deficits ◽  
The World ◽  
Sensory Evidence ◽  
Perceptual Threshold

Abstract Prominent theories suggest that symptoms of schizophrenia stem from learning deficiencies resulting in distorted internal models of the world. To test these theories further, we used a visual statistical learning task known to induce rapid implicit learning of the stimulus statistics. In this task, participants are presented with a field of coherently moving dots and are asked to report the presented direction of the dots (estimation task), and whether they saw any dots or not (detection task). Two of the directions were more frequently presented than the others. In controls, the implicit acquisition of the stimuli statistics influences their perception in two ways: (i) motion directions are perceived as being more similar to the most frequently presented directions than they really are (estimation biases); and (ii) in the absence of stimuli, participants sometimes report perceiving the most frequently presented directions (a form of hallucinations). Such behaviour is consistent with probabilistic inference, i.e. combining learnt perceptual priors with sensory evidence. We investigated whether patients with chronic, stable, treated schizophrenia (n = 20) differ from controls (n = 23) in the acquisition of the perceptual priors and/or their influence on perception. We found that although patients were slower than controls, they showed comparable acquisition of perceptual priors, approximating the stimulus statistics. This suggests that patients have no statistical learning deficits in our task. This may reflect our patients’ relative wellbeing on antipsychotic medication. Intriguingly, however, patients experienced significantly fewer (P = 0.016) hallucinations of the most frequently presented directions than controls when the stimulus was absent or when it was very weak (prior-based lapse estimations). This suggests that prior expectations had less influence on patients’ perception than on controls when stimuli were absent or below perceptual threshold.

scholarly journals Model-based learning deficits in compulsivity are linked to faulty representations of task structure

2020 ◽  
Author(s):  
Tricia X.F. Seow ◽  
Redmond O’Connell ◽  
Claire M. Gillan
Keyword(s):  
Learning Task ◽  
Task Structure ◽  
Learning Deficits ◽  
Accurate Model ◽  
Model Based ◽  
Relational Knowledge ◽  
Band Power ◽  
The World ◽  
Underlying Causes ◽  
Eeg Recordings

AbstractIndividuals with higher levels of compulsivity exhibit poorer performance on tasks that require model-based planning but the underlying causes have yet to be established. Here, we sought to determine whether these deficits stem from impoverished action-outcome relational knowledge (i.e. issues building an accurate model of the world) and/or an inability to translate models into action. 192 participants performed a two-step reinforcement learning task with concurrent EEG recordings. We found that representations of task-relevant action-outcome associations reflected in reaction time and parietal-occipital alpha-band power were stronger in individuals whose decisions were more model-based, and critically, were weaker in those high in compulsivity. At the time of choice, mid-frontal theta power, a general marker of cognitive control, was also negatively associated with compulsivity, but not model-based planning. These data suggest that model-based planning deficits in compulsive individuals may arise from failures in building an accurate model of the world.

Rapid Serial Auditory Presentation

2015 ◽  
Vol 62 (5) ◽  
pp. 346-351 ◽  
Author(s):  
Ana Franco ◽  
Julia Eberlen ◽  
Arnaud Destrebecqz ◽  
Axel Cleeremans ◽  
Julie Bertels
Keyword(s):  
Statistical Learning ◽  
Reaction Times ◽  
Visual Presentation ◽  
Detection Task ◽  
Speech Segmentation ◽  
Auditory Presentation ◽  
Indirect Measure ◽  
Speech Stream ◽  
Adult Participants ◽  
Presentation Procedure

Abstract. The Rapid Serial Visual Presentation procedure is a method widely used in visual perception research. In this paper we propose an adaptation of this method which can be used with auditory material and enables assessment of statistical learning in speech segmentation. Adult participants were exposed to an artificial speech stream composed of statistically defined trisyllabic nonsense words. They were subsequently instructed to perform a detection task in a Rapid Serial Auditory Presentation (RSAP) stream in which they had to detect a syllable in a short speech stream. Results showed that reaction times varied as a function of the statistical predictability of the syllable: second and third syllables of each word were responded to faster than first syllables. This result suggests that the RSAP procedure provides a reliable and sensitive indirect measure of auditory statistical learning.

scholarly journals Multi-Task Learning Using Task Dependencies for Face Attributes Prediction

2019 ◽  
Vol 9 (12) ◽  
pp. 2535
Author(s):  
Di Fan ◽  
Hyunwoo Kim ◽  
Jummo Kim ◽  
Yunhui Liu ◽  
Qiang Huang
Keyword(s):  
Human Computer Interaction ◽  
Video Surveillance ◽  
State Of The Art ◽  
Learning Task ◽  
Face Verification ◽  
Task Learning ◽  
The World ◽  
In The Wild ◽  
And Gender ◽  
Learning Architectures

Face attributes prediction has an increasing amount of applications in human–computer interaction, face verification and video surveillance. Various studies show that dependencies exist in face attributes. Multi-task learning architecture can build a synergy among the correlated tasks by parameter sharing in the shared layers. However, the dependencies between the tasks have been ignored in the task-specific layers of most multi-task learning architectures. Thus, how to further boost the performance of individual tasks by using task dependencies among face attributes is quite challenging. In this paper, we propose a multi-task learning using task dependencies architecture for face attributes prediction and evaluate the performance with the tasks of smile and gender prediction. The designed attention modules in task-specific layers of our proposed architecture are used for learning task-dependent disentangled representations. The experimental results demonstrate the effectiveness of our proposed network by comparing with the traditional multi-task learning architecture and the state-of-the-art methods on Faces of the world (FotW) and Labeled faces in the wild-a (LFWA) datasets.

scholarly journals LIP activity in the interstimulus interval of a change detection task biases the behavioral response

2015 ◽  
Vol 114 (5) ◽  
pp. 2637-2648 ◽  
Author(s):  
Fabrice Arcizet ◽  
Koorosh Mirpour ◽  
Daniel J. Foster ◽  
Caroline J. Charpentier ◽  
James W. Bisley
Keyword(s):  
Eye Movements ◽  
Change Detection ◽  
Behavioral Response ◽  
Interstimulus Interval ◽  
Detection Task ◽  
Covert Attention ◽  
Change Detection Task ◽  
Lateral Intraparietal Area ◽  
Overt Attention ◽  
The World

When looking around at the world, we can only attend to a limited number of locations. The lateral intraparietal area (LIP) is thought to play a role in guiding both covert attention and eye movements. In this study, we tested the involvement of LIP in both mechanisms with a change detection task. In the task, animals had to indicate whether an element changed during a blank in the trial by making a saccade to it. If no element changed, they had to maintain fixation. We examine how the animal's behavior is biased based on LIP activity prior to the presentation of the stimulus the animal must respond to. When the activity was high, the animal was more likely to make an eye movement toward the stimulus, even if there was no change; when the activity was low, the animal either had a slower reaction time or maintained fixation, even if a change occurred. We conclude that LIP activity is involved in both covert and overt attention, but when decisions about eye movements are to be made, this role takes precedence over guiding covert attention.

scholarly journals Changes of mind and absolute evidence

2019 ◽  
Author(s):  
William Turner ◽  
Daniel Feuerriegel ◽  
Milan Andrejevic ◽  
Robert Hester ◽  
Stefan Bode
Keyword(s):  
Decision Process ◽  
Initial Response ◽  
Luminance Ratio ◽  
Noise Sources ◽  
Initial Decision ◽  
Luminance Difference ◽  
The World ◽  
Sensory Evidence

To navigate the world safely, we often need to rapidly ‘change our mind’ about decisions. Current models assume that initial decisions and change-of-mind decisions draw upon common sources of sensory evidence. In two-choice scenarios, this evidence may be ‘relative’ or ‘absolute’. For example, when judging which of two objects is the brightest, the luminance difference and luminance ratio between the two objects are sources of ‘relative’ evidence, which are invariant across additive and multiplicative luminance changes. Conversely, the overall luminance of the two objects combined is a source of ‘absolute’ evidence, which necessarily varies across symmetric luminance manipulations. Previous studies have shown that initial decisions are sensitive to both relative and absolute evidence; however, it is unknown whether change-of-mind decisions are sensitive to absolute evidence. Here, we investigated this question across two experiments. In each experiment participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli remained on screen for a brief period and participants could change their response. To investigate the effect of absolute evidence, the overall luminance of the two squares was varied whilst either the luminance difference (Experiment 1) or luminance ratio (Experiment 2) was held constant. In both experiments we found that increases in absolute evidence led to faster, less accurate initial responses and slower changes of mind. Change-of-mind accuracy decreased when the luminance difference was held constant, but remained unchanged when the luminance ratio was fixed. The initial response effects could be explained by the presence of input-dependent noise within the decision process, varying either within or across trials. However, the change-of-mind effects could not be captured by existing models, nor by two modified models which included input-dependent noise sources. This suggests that that the continued integration of sensory evidence following an initial decision operates differently to that described in existing theoretical accounts.

Inferential Anti-skepticism about Perception

2021 ◽  
pp. 35-56
Author(s):  
Michael Bergmann
Keyword(s):  
A Priori ◽  
Sensory Experience ◽  
A Priori Knowledge ◽  
Skeptical Hypothesis ◽  
The World ◽  
Sensory Evidence ◽  
Priori Knowledge

This chapter examines multiple kinds of deductive and nondeductive anti-skeptical arguments from our sensory experience to the likely truth of our perceptual beliefs based on that evidence and finds them all wanting. In the first two sections, it briefly considers deductive anti-skeptical arguments (of the theological and transcendental variety), inductive anti-skeptical arguments from past correlations of sensory experience with true perceptual beliefs based on it, and anti-skeptical arguments based on a priori knowledge of probabilistic principles saying that our sensory evidence for our perceptual beliefs makes probable the truth of those beliefs. In the final three sections, the focus turns to abductive or inference to the best explanation (IBE) arguments, which are currently the most popular anti-skeptical arguments. IBE anti-skeptical arguments conclude that our sensory experience, or some feature of it, is best explained by the truth of our perceptual beliefs. These three sections argue that we lack good reasons for thinking that our sensory experience is better explained by a Standard Hypothesis (saying that the world is approximately as it seems) than by a skeptical hypothesis, such as the hypothesis that a deceptive demon wants to mislead us into falsely believing the world is as it seems.

scholarly journals Statistical learning in domestic chicks is modulated by strain and sex

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chiara Santolin ◽  
Orsola Rosa-Salva ◽  
Bastien S. Lemaire ◽  
Lucia Regolin ◽  
Giorgio Vallortigara
Keyword(s):  
Sex Differences ◽  
Statistical Learning ◽  
Comparative Research ◽  
Learning Task ◽  
Human Infants ◽  
Sensory Inputs ◽  
Automated Tracking ◽  
Domestic Chicks ◽  
Continuous Stream

Abstract Statistical learning is a key mechanism for detecting regularities from a variety of sensory inputs. Precocial newborn domestic chicks provide an excellent model for (1) exploring unsupervised forms of statistical learning in a comparative perspective, and (2) elucidating the ecological function of statistical learning using imprinting procedures. Here we investigated the role of the sex of the chicks in modulating the direction of preference (for familiarity or novelty) in a visual statistical learning task already employed with chicks and human infants. Using both automated tracking and direct human coding, we confirmed chicks’ capacity to recognize the presence of a statistically defined structure underlying a continuous stream of shapes. Using a different chicken strain than previous studies, we were also able to highlight sex differences in chicks’ propensity to approach the familiar or novel sequence. This could also explain a previous failure to reveal statistical learning in chicks which sex was however not determined. Our study confirms chicks’ ability to track visual statistics. The pivotal role of sex in determining familiarity or novelty preferences in this species and the interaction with the animals’ strain highlight the importance to contextualize comparative research within the ecology of each species.

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