Stimulus over-selectivity occurs when one aspect of the environment controls behavior at the expense of other equally salient aspects. Participants were trained on a match-to-sample (MTS) discrimination task. Levels of over-selectivity in a group of children (4-18 years) with Autism Spectrum Disorders (ASD) were compared with a mental-aged matched…

Schedules of reinforcement typically produce reliable patterns of behaviour, and one factor that can cause deviations from these normally reliable patterns is schizotypy. Low scorers on the unusual experiences subscale of the Oxford-Liverpool Inventory of Feelings and Experiences performed as expected on a yoked random-ratio (RR), random-interval…

In three experiments, human participants pressed the space bar on a computer keyboard to earn points on random-ratio (RR) and random-interval (RI) schedules of reinforcement. Verbalized contingency awareness (CA) for each schedule was measured after the entire task (Experiments 1 and 2), or after each RR-RI trial (Experiment 3). In all three…

The conditions under which stimulus over-selectivity occurred were studied using a matching-to-sample procedure with non-autistic adults. A matching-to-sample discrimination learning task with a number of sample-comparison retention intervals was used. The results demonstrated that an increase in retention interval increased the degree of stimulus…

Response rates under random-interval schedules are lower when a brief (500 ms) signal accompanies reinforcement than when there is no signal. The present study examined this signaled-reinforcement effect and its relation to resistance to change. In Experiment 1, rats responded on a multiple random-interval 60-s random-interval 60-s schedule, with…