Encoding and retrieval processes in retroactive inhibition

Abstract

Three experiments on retroactive inhibition are reported. They deal with the negative relation between response-class similarity and retention of the first list. Although in several previous experiments on this subject such a relation was demonstrated, we propose a hypothesis in which this “Same-Different effect” is thought to be dependent on characteristics of stimulus encoding. Especially, it is assumed that if ordinal relations between the stimulus terms are emphasized, a two-stage retrieval plan is executed in which response-class information is used during the first step. In all other cases a one-stage retrieval plan will be followed in which category cues are bypassed. In accordance with the hypothesis the results of Experiments I and II show a small and nonsignificant Same-Different effect if letters are used as stimuli. In Experiment III a substantial, though insignificant, difference in favor of the hypothesis was demonstrated between adjacent and nonadjacent number stimuli. Finally, implications are discussed for theories about retroactive inhibition.