Temporal changes in interference

Abstract

A series of five experiments investigating temporal changes in retroactive inhibition (RI) and proactive inhibition (PI) is reported. In the first four experiments changes in retention were measured by unpaced tests over intervals of the order of 20 min. Conditions of acquisition and methods of testing were varied with a view to identifying the factors determining absolute rises in first-list recall (“spontaneous recovery”) and decrements in the recall of interpolated lists (PI). Both of these phenomena were observed and were attributed to the dissipation of a set, established through interpolated learning, to give the most recently learned responses in recall. In the fifth experiment RI and PI were measured on paced tests after intervals of 20 min and 48 hrs. The amounts of RI and PI did not differ significantly after 20 min, and showed no further reliable changes over the 48-hr interval. The results indicate that the level of interference on paced tests is determined largely by the degree of reduction in response availability.