The scheme of differential reinforcement of low response rates (DRL) is largely employed in behavioral studies of temporal discrimination. However, it is not clear what the behavioral effects of different deprivation levels on the behavior under the control of temporal schemes of reinforcement are, especially the DRL. The present study tested the hypothesis that more severe deprivation disrupts the subjects' performance under DRL control, compared to that of subjects exposed lower levels of deprivation. Three groups of rats initially submitted to three different food deprivation levels (80, 90 and 100% ad lib) were trained under a DRL-20 s scheme. After the training, deprivation was manipulated intra-group, in two consecutive testing conditions: the deprivation of the 80% group was changed to 100% ad lib and deprivation of the 100% group was changed to 80% ad lib; the 90% deprived group was kept under this level of deprivation across all experimental sessions as a control-group. The animals showed a worse performance in the DRL task when the deprivation transition went from 100% to 80% ad lib and a better performance when the transition was from 80% to 100% ad lib. There were no systematic changes in performance under the transitions from 90% to 100% or from 90% to 80% ad lib. The results indicate that the rats performance in a DRL is affected not only by the state generated by a specific level of food deprivation, but also by physiological and cognitive states acquired in preceding situations.
Rats; DRL; food deprivation; inter response-times
