Cognitive abnormalities in Autism Spectrum Disorders (ASD) have been attributed to a preference for local processing, alongside global processing difficulties. Whereas local processing focuses on the details, global processing aims for a more holistic, integrative picture. An important skill, often associated with global processing, is the ability to use context. Yet, research findings regarding the ability of individuals with ASD to understand context have been inconclusive.
A common paradigm that enables a separate assessment of local and global visual processing uses stimuli that have been filtered to reveal only high or low frequency bands, respectively. Studies that have used this paradigm with social stimuli, described a tendency for local processing among individuals with ASD. However, no such studies examined the high and low frequency processing of non-social stimuli. Furthermore, the ability of individuals with ASD to use context in order to enhance their global visual processing has not been previously explored.
Objectives: This study examined the ability of high functioning adolescents with ASD to use context when processing social and non-social stimuli, and their ability to harness contextual information in support of their processing of these visual stimuli.
Methods: Sixteen children and adolescents (aged 11-17) with ASD and sixteen Typically Developing (TD) controls, matched on chronological and mental age, took two computerized recognition tasks, one presenting social stimuli (facial expressions) and the other presenting non-social stimuli (animal face photos). In order to examine the ability to use context, each visual stimulus was preceded by an auditory prime that was either congruent, incongruent, or neutral to it. In order to examine local and global processing style in each task, visual stimuli were presented in three spatial frequency conditions: High Frequency (HF), Low Frequency (LF), and Broad-Band (BB). Response time for correct responses was recorded for each condition.
Results: Reaction time analyses for both social and non-social stimuli confirmed main effects of group (TD<ASD), context (Congruent<Incongruent=Neutral), and spatial frequency (BB<LF=HF). Analysis for reaction time to facial expressions showed no group by context interactions on HF and BB spatial frequency conditions. However, on the LF (i.e., global) condition, only the TD group performed faster on the congruent condition, compared to the incongruent and neutral conditions, whereas the ASD group showed no such improvement due to supporting context. Analysis of reaction time to non-social stimuli showed no significant interactions with group.
Conclusions: High Functioning adolescents with ASD show intact global and local visual processing of both social and non-social stimuli. However, their ability to support global processing of social stimuli through the use of context is compromised. These findings may affect our understanding of current cognitive theories of ASD and their clinical applications.
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