Free classification as a window on executive functioning in autism spectrum disorders.

Spontaneous classification was assessed using a free serial search task in 18 school-aged children at the high functioning end of the autistic spectrum and compared with results from age-matched typically developing controls. The task required participants to touch shapes in an exhaustive non-repetitive sequence. The positions of the items varied randomly between touches. The objective was to measure the extent to which children with autism and Asperger's syndrome could spontaneously utilise category information such as shape and color to organise their search. There were no group differences on measures of sequential control and levels of categorization once age and IQ had been partialled out. The results are contrasted with findings from the same lab using a size seriation task.