An analysis of stimulus overselectivity in adults with autism

Abstract

The studies reported in this paper examined the effect of varying background colour and relative location of the stimulus on stimulus control in adults with autism and a mental-age matched control group (all adults with intellectual disability). The focus was on extending the stimulus overselectivity literature. The participants were taught to button-press in the presence of the "correct" visual stimulus presented on a computer monitor but to withhold from pressing when the "incorrect" stimulus was presented. Once the discrimination task had been learned, testing was then conducted to identify which components of the stimulus (location or size) had acquired stimulus control. It was found that the participants produced stimulus generalisation gradients which are comparable with other populations. Operationally defined stimulus overselectivity was also evident in adults with autism and controls. This is one of the few demonstrations of this in an adult population. Varying background colour in a discrimination task containing two relevant cues (location and size) did not lead to more evidence of stimulus overselectivity in either adults with autism or mental-age matched controls (study 1). Also, varying the relative placement of the training stimuli on the monitor had no effect (study 2). However, study 2 indicated a difference in stimulus overselectivity between the groups. The difference appeared to be related to the number of stimuli presented and the difference was in the opposite direction to that predicted. That is, participants with autism were less overselective than the mental-age matched control group. The relevance of these findings for the instruction of people with autism and intellectual disability is discussed.