Instrumental performance and time between reinforcements: Intimate relation to learning or memory retrieval?

Abstract

According to scalar expectancy theory (SET), instrumental performance is determined by the ratio of the time between reinforcements in the trial (T(T)) to the overall time between reinforcements (T(O)). Groups for which the T(O)|T(T) ratio is the same should perform similarly. According to the sequential-memory view, the memory of nonreward becomes a signal for reward, and thereby promotes strong responding, when that memory is retrieved on a reward trial. In each of three runway investigations employing rats in a runway, two groups were compared that had the same T(O)|T(T) ratio but that differed in the tendency to retrieve the memory of nonreward on a rewarded trial. In each investigation faster running on critical nonrewarded trials was associated with the group having the stronger tendency to retrieve the memory of nonreward on a rewarded trial. These findings are consistent with the predictions of the sequential-memory view, as well as with certain earlier findings, but are inconsistent with SET. It was indicated that the groups compared here were matched along a considerable number of dimensions- an unprecedented number for a varied reward investigation.