Abstract
Many researches found out that many of autistic children showed selective stimulus control (i. e. stimulus overselectivity; SO) when they had been trained discrimination task with stimulus complex. In other researches, some of younger normal, mentally retarded and learning disabled children showed SO, too. But there are only a few studies to evaluate whether or not SO is differentially influenced by the two sets of stimulus complex. The purpose of this investigation was to assess the relative effects of two sets of visual stimulus complex on SO; "stimulus with spatially independent elements" (SSIE, e. g. two simple shapes) and "multidimensional stimulus" (MS, e. g. colored shape). Seven autistic, seven MA matched normal children (3 year-old) , nine 4 year-old and nine 6 year-old normal children participated. The children were trained on the simultaneous discrimination task with each of the stimulus sets. And then the subjects were tested on individual elements to determine which element or elements were controlling subject's responses. The results showed that (1) the percentage of overselective subjects did not differ between autistic and MA matched normal children in both stimulus conditions ; but (2) the total percentage of subjects controlled by both elements were significantly more with MS than SSIE; and (3) it was not evident that the percentage of overselective subjects might decrease with MA. The implications -of these data for the notion of stimulus overselectivity and futher research were discussed.
