Stimulus overselectivity in learning disabled children.

Stimulus overselectivity, a phenomenon exhibited by autistic and institutionalized retarded individuals, was examined in mildly handicapped and nonhandicapped public school children. Subjects were 16 young, educable mentally retarded, 16 learning disabled, 15 nonhandicapped first- and second-graders, and 16 older, educable retarded students. The children were trained on a 3-component visual discrimination task and then tested on individual elements to determine which element or elements were controlling subject responses. Nine of the young educable mentally retarded children and eight of the learning disabled students showed some overselectivity. The majority of overselective retarded children were controlled by only one of the three components of the training cue, whereas the majority of the overselective learning disabled children responded to the discrimination task on the basis of two of the three components. No overselectivity was exhibited by the nonhandicapped students. All three cue components were also functional in controlling the responding of 14 of the 16 older retarded students, but two children were under the control of only one cue. The research indicated that in terms of overselectivity, learning disabled children respond more like young, mildly retarded children than they do like nonhandicapped ones. The demonstration of stimulus overselectivity in a sizable portion of a learning disabled sample may have implications for a more empirically based approach to this handicapped population.