Ruth Van der Hallen

Precise minds in uncertain worlds: predictive coding in autism.

There have been numerous attempts to explain the enigma of autism, but existing neurocognitive theories often provide merely a refined description of 1 cluster of symptoms. Here we argue that deficits in executive functioning, theory of mind, and central coherence can all be understood as the consequence of a core deficit in the flexibility with which people with autism spectrum disorder can process violations to their expectations. More formally we argue that the human mind processes information by making and testing predictions and that the errors resulting from violations to these predictions are given a uniform, inflexibly high weight in autism spectrum disorder. The complex, fluctuating nature of regularities in the world and the stochastic and noisy biological system through which people experience it require that, in the real world, people not only learn from their errors but also need to (meta-)learn to sometimes ignore errors. Especially when situations (e.g., social) or stimuli (e.g., faces) become too complex or dynamic, people need to tolerate a certain degree of error in order to develop a more abstract level of representation. Starting from an inability to flexibly process prediction errors, a number of seemingly core deficits become logically secondary symptoms. Moreover, an insistence on sameness or the acting out of stereotyped and repetitive behaviors can be understood as attempts to provide a reassuring sense of predictive success in a world otherwise filled with error. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Global processing takes time: A meta-analysis on local–global visual processing in ASD.

What does an individual with autism spectrum disorder (ASD) perceive first: the forest or the trees? In spite of 30 years of research and influential theories like the weak central coherence (WCC) theory and the enhanced perceptual functioning (EPF) account, the interplay of local and global visual processing in ASD remains only partly understood. Research findings vary in indicating a local processing bias or a global processing deficit, and often contradict each other. We have applied a formal meta-analytic approach and combined 56 articles that tested about 1,000 ASD participants and used a wide range of stimuli and tasks to investigate local and global visual processing in ASD. Overall, results show no enhanced local visual processing nor a deficit in global visual processing. Detailed analysis reveals a difference in the temporal pattern of the local-global balance, that is, slow global processing in individuals with ASD. Whereas task-dependent interaction effects are obtained, gender, age, and IQ of either participant groups seem to have no direct influence on performance. Based on the overview of the literature, suggestions are made for future research.

Illusory Visual Completion of an Object's Invisible Backside Can Make Your Finger Feel Shorter

In a well-known magic trick known as multiplying balls, conjurers fool their audience with the use of a semi-spherical shell, which the audience perceives as a complete ball [1]. Here, we report that this illusion persists even when observers touch the inside of the shell with their own finger. Even more intriguingly, this also produces an illusion of bodily self-awareness in which the finger feels shorter, as if to make space for the purely illusory volume of the visually completed ball. This observation provides strong evidence for the controversial and counterintuitive idea that our experience of the hidden backsides of objects is shaped by genuine perceptual representations rather than mere cognitive guesswork or imagery [2].

Brief Report: Reduced Grouping Interference in Children with ASD: Evidence from a Multiple Object Tracking Task

This study was inspired by the more locally oriented processing style in autism spectrum disorders (ASD). A modified multiple object tracking (MOT) task was administered to a group of children with and without ASD. Participants not only had to distinguish moving targets from distracters, but they also had to track targets when they were visually grouped to distracters, a manipulation which has a detrimental effect on tracking performance in adults. MOT performance in the ASD group was also affected by grouping, but this effect was significantly reduced. This result highlights how the reduced bias towards more global processing in ASD could influence further stages of cognition by altering the way in which attention selects information for further processing.

Disentangling signal and noise in autism spectrum disorder

HighlightsIndividuals with ASD may have difficulties separating signal from noise.This could be explained by deficient precision‐setting.It implies problems in learning expectations on input variability over experiences.It creates problems in context‐dependent assignment of salience of inputs.It decreases robustness in perception (cf. coherent motion). Abstract Predictive coding has recently been welcomed as a fruitful framework to understand autism spectrum disorder. Starting from an account centered on deficient differential weighting of prediction errors (based in so‐called precision estimation), we illustrate that individuals with autism have particular difficulties with separating signal from noise, across different tasks. Specifically, we discuss how deficient precision‐setting is detrimental for learning in unstable environments, for context‐dependent assignment of salience to inputs, and for robustness in perception, as illustrated in coherent motion paradigms.

Local-global processing bias is not a unitary individual difference in visual processing

ABSTRACT A large body of research reports individual differences in local and global visual processing in relation to expertise, culture and psychopathology. However, recent research has suggested that various different measures of local‐global processing are not strongly associated with one another, calling its construct validity into question. The current study sought to further explore the validity of local‐global processing biases in perception by developing three tasks based on two existing paradigms: the Embedded Figures Test (EFT) and the Navon hierarchical letters task. The newly developed tasks aimed to control for stimulus and response factors that may have impacted upon the reliability of previous research. They were administered to a large sample of undergraduate students (N > 100). The results of two new versions of the EFT indicated that disembedding performance is influenced by the structure of the embedding context. In addition, global precedence and interference in the Navon task remained present even when local attentional approaches to global hierarchical stimuli were restricted. Inter‐task correlations within the EFT were high but low between the EFT and the Navon task, lending support to the notion that local‐global processing is not a monolithic construct, but representative of a number of distinct perceptual abilities and biases. Future research may use these task distinctions to pinpoint more precisely which aspects of perceptual processing characterise specific (clinical) participant populations.

In the Eye of the Beholder: Rapid Visual Perception of Real-Life Scenes by Young Adults with and Without ASD

Typically developing (TD) adults are able to extract global information from natural images and to categorize them within a single glance. This study aimed at extending these findings to individuals with autism spectrum disorder (ASD) using a free description open-encoding paradigm. Participants were asked to freely describe what they saw when looking at briefly presented real-life photographs. Our results show subtle but consistent group-level differences. More specifically, individuals with ASD spontaneously reported the presence of people in the display less frequently than TD participants, and they grasped the gist of the scene less well. These findings argue for a less efficient rapid feedforward processing of global semantic aspects and a less spontaneous interpretation of socially salient information in ASD.

Ultra-Rapid Categorization of Meaningful Real-Life Scenes in Adults With and Without ASD

In comparison to typically developing (TD) individuals, people with autism spectrum disorder (ASD) appear to be worse in the fast extraction of the global meaning of a situation or picture. Ultra-rapid categorization [paradigm developed by Thorpe et al. (Nature 381:520–522, 1996)] involves such global information processing. We therefore tested a group of adults with and without ASD, without intellectual disability, on a set of ultra-rapid categorization tasks. Individuals with ASD performed equally well as TD individuals except when the task required the categorization of social interactions. These results argue against a general deficit in ultra-rapid gist perception in people with ASD, while suggesting a more specific problem with the fast processing of information about social relations.

Multiple Object Tracking Reveals Object-Based Grouping Interference in Children with ASD

The multiple object tracking (MOT) paradigm has proven its value in targeting a number of aspects of visual cognition. This study used MOT to investigate the effect of object-based grouping, both in children with and without autism spectrum disorder (ASD). A modified MOT task was administered to both groups, who had to track and distinguish four targets that moved randomly amongst four distracters, irrespective of the grouping condition. No group difference was revealed between children with and without ASD: both showed adequate MOT abilities and a similar amount of grouping interference. Implications of the current result are considered for previous MOT studies, the developmental trajectory of perceptual grouping, and the idea of heightened sensitivity to task characteristics in ASD.

Developing the Leuven Embedded Figures Test (L-EFT): testing the stimulus features that influence embedding

Background The Embedded Figures Test (EFT, developed by Witkin and colleagues (1971)) has been used extensively in research on individual differences, particularly in the study of autism spectrum disorder. The EFT was originally conceptualized as a measure of field (in)dependence, but in recent years performance on the EFT has been interpreted as a measure of local versus global perceptual style. Although many have used the EFT to measure perceptual style, relatively few have focused on understanding the stimulus features that cause a shape to become embedded. The primary aim of this work was to investigate the relation between the strength of embedding and perceptual grouping on a group level. Method New embedded figure stimuli (both targets and contexts) were developed in which stimulus features that may influence perceptual grouping were explicitly manipulated. The symmetry, closure and complexity of the target shape were manipulated as well as its good continuation by varying the number of lines from the target that continued into the context. We evaluated the effect of these four stimulus features on target detection in a new embedded figures task (Leuven Embedded Figures Test, L-EFT) in a group of undergraduate psychology students. The results were then replicated in a second experiment using a slightly different version of the task. Results Stimulus features that influence perceptual grouping, especially good continuation and symmetry, clearly affected performance (lower accuracy, slower response times) on the L-EFT. Closure did not yield results in line with our predictions. Discussion These results show that some stimulus features, which are known to affect perceptual grouping, also influence how effectively a stimulus becomes embedded in different contexts. Whether these results imply that the EFT measures individual differences in perceptual grouping ability must be further investigated.