Evelyn Gibson | PubMed Health

PubMed2005

The effect of concurrent task load on stimulus over-selectivity.

Stimulus over-selectivity is a phenomenon displayed by individuals with autism, and has been implicated as a basis for many autistic-spectrum symptoms. In four experiments, non-autistic adult participants were required to learn a simple discrimination using picture cards, and then were tested for the emergence of stimulus over-selectivity, both with and without a concurrent task. Greater stimulus over-selectivity was noted when participants completed the concurrent task. The results are discussed in relation to the implications for the development of a model of memory deficits in autism.

Adult↗

PubMed2005

Stimulus over-selectivity in rats.

The present study explored whether a similar phenomenon to stimulus over-selectivity occurred in rats, in the hope of establishing a non-human model for the autism. Rats were serially presented with two-15 seconds, two-element compound stimuli prior to the delivery of food, in an appetitive classical conditioning procedure. Each compound stimulus consisted of two lights. Once the rats had acquired a conditioned response (CR) to the stimuli, they were presented with each of the component elements separately in extinction. The rats demonstrated greater conditioning to components of the compound presented just prior to reinforcement than to the components of the temporally distant compound. However, there was a smaller difference between CRs to the components of the compound presented just prior to reinforcement (i.e. less overshadowing) than between the components of the temporally distant compound. It is suggested that rats demonstrated a form of stimulus over-selectivity, resulting in greater overshadowing of one cue by another. Such results may form the basis of a viable non-human model of this symptom of autistic spectrum disorder.

Animals↗