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Variables Influencing Stimulus Overselectivity In Normally Developing Children




Smith, Kimberley

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Stimulus overselectivity is a type of responding observed in children and adults with autism spectrum disorders and mental retardation. It involves responding that is controlled by a small, often irrelevant portion of a total stimulus that results in other stimulus components failing to exert control over responding. Although this phenomenon has been examined frequently in individuals with autism spectrum disorders and mental retardation, few studies are available examining overselective responding in normally developing children and adults. Evidence that is available suggests that young normally developing children respond to few components of a complex stimulus. The present experiment was designed to identify variables influencing overselective responding in preschoolers and more specifically, what type of stimulus presentation might result in overselective responding. Participants, ages 3.11, 4.2 and 4.6, were presented a delayed matching to sample task displayed on a computer touch screen. The matching task was presented as a game to the children in groups of 10 trials. Stimuli appeared on the screen and the children were told to find the one that matches the first picture. Matching tasks involving size, shape, number of stimuli and configuration of stimuli within a stimulus complex were presented. Participants showed decreases in correctly matching the dimension of size when stimuli were complex and of high number. Additionally, results from the configuration condition showed that when responses to the top left shape in the configuration were required, correct responding was 50% or less across subjects suggesting that the stimulus dimensions of size and configuration within these conditions was not exerting stimulus control over participants responding. This observation of overselective responding illustrates the effect that stimulus features may have on matching responses. The results also make apparent the implications of stimulus arrangement on correct responding and the issues this poses for teachers and trainers. In addition, there does not seem to be a distinct phenomenon in any specific sense different than stimulus control deficits. Rather, it could be argued that certain stimulus presentations tend to generate particular types of errors. Conceptual and definitional issues surrounding stimulus overselectivity should be reexamined.