Cécilie Rondan

Attention to low-and high-spatial frequencies in categorizing facial identities, emotions and gender in children with autism

This study was aimed at investigating face categorization strategies in children with autistic spectrum disorders (ASD). Performance of 17 children with ASD was compared to that of 17 control children in a face-matching task, including hybrid faces (composed of two overlapping faces of different spatial bandwidths) and either low- or high-pass filtered faces. Participants were asked to match faces on the basis of identity, emotion or gender. Results revealed that children with ASD used the same strategies as controls when matching faces by gender. By contrast, in the identity and the emotion conditions, children with ASD showed a high-pass bias (i.e., preference for local information), contrary to controls. Consistent with previous studies on autism, these findings suggest that children with ASD do use atypical (local-oriented) strategies to process faces.

Processing of compound visual stimuli by children with autism and Asperger syndrome

A typical modes of visual processing are common in individuals with autism. In particular, and unlike typically developing children, children with autism tend to process the parts of a complex object as a priority, rather than attending to the object as a whole. This bias for local processing is likely to be due to difficulties in assembling subparts into a coherent whole, as proposed by Frith (1989) using the term “weak central coherence” or WCC. This study was aimed to better characterize the processing of complex visual stimuli by children with autism. Thirteen children with autistic spectrum disorders were individually paired with children of two control groups, one matched on verbal mental age (VMA) and one matched on chronological age (CA). Participants from the three groups were tested in two tasks. The first task involved hierarchical global/local stimuli, inspired by Navon (1977). The second task employed compound face‐like or geometrical stimuli. This task emphasized the processing of configural...

Global and local music perception in children with Williams syndrome

Musical processing can be decomposed into the appreciation of global and local elements. This global/local dissociation was investigated with the processing of contour-violated and interval-violated melodies. Performance of a group of 16 children with Williams syndrome and a group of 16 control children were compared in a same–different task. Control participants were more accurate in detecting differences in the contour-violated than in the interval-violated condition while Williams syndrome individuals performed equally well in both conditions. This finding suggests that global precedence may occur at an early perceptual stage in normally developing children. In contrast, no such global precedence is observed in the Williams syndrome population. These data are discussed in the context of atypical cognitive profiles of individuals with Williams syndrome.

Mr. Grimace or Ms. Smile Does Categorization Affect Perceptual Processing in Autism

This study compared the influence of categorization on perceptual processing in adults with autistic spectrum disorders (ASD) and normal control participants. Participants were asked to categorize hybrid faces (composed of two overlapped faces of different spatial bandwidths) by gender and emotion. Control participants exhibited a bias for low-pass information during gender categorization and a bias for high-pass information during emotion categorization. By contrast, adults with ASD showed the same low-pass bias in both tasks. This absence of a shift in processing style in the ASD group is discussed in terms of diminished top-down modulation in autism.

Global and local processing in Williams syndrome: drawing versus perceiving.

It has been hypothesized that a local processing bias underlies overall visuospatial impairments in Williams syndrome (WS). However, recent studies have challenged this hypothesis by providing evidence against a local processing bias at the perceptual level. The aim of the present study was to further examine drawing and perceptual skills in children with WS using closely matched-hierarchical stimuli. In the drawing task children with WS exhibited a local processing bias. However, no significant preferential bias was found in the perceptual task. This indicates that children with WS do not systematically present a preferential bias for local information. Taken together the findings of the present study suggest that perceptual processing deficits per se are unlikely to explain local processing biases in visuoconstructive tasks often described in people with WS.

Social Relevance Boosts Context Processing in Williams Syndrome

The aim of the present study was to determine whether individuals with Williams syndrome (WS) are able to recognize facial expressions of emotion and objects missing on the basis of contextual cues. Sixteen individuals with WS were compared to typically developing individuals matched on chronological and mental age. WS group performed significantly lower than both control groups in object recognition. By contrast, no such group differences were found in facial expression recognition, suggesting that individuals with WS do have the ability to process contextual cues. However, this ability seems to be boosted when they are to process socially relevant cues.

Behavioural indexes of callosal functioning in Williams syndrome

Williams syndrome (WS) is a neurogenetic disorder that stems from a microdeletion on chromosome 7. Recent anatomical studies have found evidence for corpus callosum abnormalities in WS. However, to date, the impact of these structural differences on callosal functionality remains unclear. The aim of the present study was to investigate interhemispheric communication and hemispheric asymmetry in individuals with WS relative to mental age-matched controls. This was assessed using bilateral and unilateral presentations of visual stimuli in a picture-naming task. Results found both groups to exhibit a bilateral field advantage and a left visual advantage on unilateral presentations. However, while a significant performance increase with age was found for controls, no such correlation was found for individuals with WS. Taken together, these findings suggest that despite some evidence for an atypical developmental pathway in WS, both interhemispheric communication and hemispheric asymmetry are functionally intact in this population.