Behavioral contrast as a function of the temporal location of reinforcement

Pigeons were trained on a multiple variable-interval variable-interval schedule of reinforcement. One component was then changed to a variation of a fixed-interval schedule in which the same rate of reinforcement was obtained as previously but the location of the reinforcer was fixed within the component. The effects of different temporal locations were compared. An increase in response rate for the unchanged variable-interval component (behavioral contrast) occurred when the reinforcer was located in the middle or at the end of the FI component, but response suppression occurred when it was located at the beginning of the component. The pattern of results cannot be explained by any previous theories of contrast. The overall response rates, and the pattern of local rates within the components, were consistent with the hypothesis that the major determinant of the contrast effect was the transition to a lower reinforcement rate following the unchanged component.     

Effects of schedule and magnitude of reinforcement under conditions of thirst motivation

In contrast to a recent finding (Macdonald, G. E., & De Toledo, L. Learning and Motivation, 1974, 5, 288–298.) the results of three experiments investigating various partial reinforcement (PRF) manipulations under conditions of thirst motivation demonstrated strong similarity to analogous manipulations involving food reward. Specifically, for animals receiving water reinforcement, PRF was shown to generate greater resistance to extinction than continuous reinforcement (Expt 1 & 3), the schedule of reinforcement was shown to interact with level of acquisition (Expt 1 and 2), and the magnitude of the partial reinforcement extinction effect was shown to be a function of reward magnitude (Expt 3). These results provide strong evidence that mechanisms which operate in partial reinforcement situations are highly similar, regardless of the type of appetitive reinforcement.     

Cognitive Offloading: Structuring the Environment to Improve Children's Working Memory Task Performance

Research has shown that adults can engage in cognitive offloading, whereby internal processes are offloaded onto the environment to help task performance. Here, we investigate an application of this approach with children, in particular children with poor working memory. Participants were required to remember and recall sequences of colors by placing colored blocks in the correct serial order. In one condition the blocks were arranged to facilitate cognitive offloading (i.e., grouped by color), whereas in the other condition they were arranged randomly. Across two experiments (total N = 166) the ordered condition improved task performance for children with low working memory ability. In addition, participants in Experiment 2 rated the difficulty of the two arrangements and performed a further condition in which they were given an opportunity to freely arrange the blocks before completing the task. Despite performing better in the ordered condition, children with low working memory ability did not rate the ordered arrangement as easier, nor did they choose an ordered arrangement when given the opportunity to do so. This research shows that cognitive offloading can also be a useful process in populations other than typical adults, and the implications of this work for supporting children with poor working memory are discussed.