Atypical saccadic scanning in autistic spectrum disorder.

Saccadic scanning was examined for typically developing (TD) adults and those with autistic spectrum disorder (ASD) during inspection of the 'Repin' picture (Yarbus, A. (1967). Eye movements and vision. New York: Plenum) under two different viewing instructions: (A) material instructions ('Estimate the material circumstances of the family'); and (B) social instructions ('Estimate how long the unexpected visitor has been away'). Proportions of fixations and viewing time on the people and the objects in the scene differed between the two task instructions for TD, but not ASD participants showing that people with ASD did not differentially sample the scene according to top down instruction. One tentative explanation for these findings is that dysfunctional or underdeveloped fronto-parietal feedback systems in ASD, could result in defective saccadic sampling strategies, leading to impairments with cognitive processing in ASD.