Objectives: To provide an updated review of the literature relevant to perceptual functioning in autism.
Methods: We conducted a review of the behavioral, cognitive, psychophysical and brain imaging literature on autistic perception spanning 2006 - 2009. New empirical and theoretical content was considered as to its consistency, or lack thereof, with the eight principles composing the 2006 EPF model.
Results: Superior pitch processing is now the second most replicated example of an autistic perceptual peak. The autistic visual system appears to be more sensitive to high spatial frequencies. Reduced crowding effects, absence of critical distances in crowding, and greater thickness in perceptual cortices, all indicate atypical neural organization. Altered lateral neural interactions are a possible elementary mechanism accounting for superior extraction of perceptual features in both visual and auditory modalities. More sensitive and rapid detection of patterns may underlie superiorities in multiple perceptual domains and be especially developed in autistics with exceptional skills. Low level perceptual abilities in autism contribute to superior visuo-constructive ability and are positively related to performance in matrix reasoning. The role of visual perception in fluid reasoning is also demonstrated by enhanced extrastriate activity during performance on Raven’s Progressive Matrices. A meta-analysis of functional imaging studies indicates that autistics’ primary and associative visual areas are consistently more active on tasks involving face, object, and written language processing, while frontal areas are less engaged. Performance on a wide range of tasks, from perception of regularities within social information, to detection of anomalies in an ecological change blindness task, to a test of logical consistency, suggests an overall more independent and versatile functioning of cognitive processes in autism.
Conclusions: Most propositions of the EPF model have been supported by results reported in recent years. In addition, there are indications for a greater role of associative perceptual areas in autistic performance peaks involving visual perceptual tasks and fluid intelligence.