Postcriterion Insertion of a Second Relevant Dimension in a Simple Discrimination Problem

Abstract

Thirty-one human Ss participated in a discrimination problem having three stages. Stage I involved one relevant dimension and one irrelevant dimension. Ss were trained to a criterion of eight successive correct responses. After reaching criterion on Stage I, Ss began Stage II, in which both the relevant and irrelevant cues from Stage I were maintained, and one more relevant and one more irrelevant dimension were added. At this point, it was possible for Ss to solve the problem by responding to the “old” relevant cue, the new cue, or both. Certain theories predict a sampling of the inserted cues; others predict they will not be sampled. In Stage III, the relevant and irrelevant cues from Stage I were dropped out. Solution of the problem could be gained only by responding to the cues inserted in Stage II. A control group was overtrained on Stage I and then went directly to Stage III. The data supported theories predicting sampling of all cues in Stage II.