Intermittent Reinforcement of a Formerly Relevant Dimension in Concept Formation

Abstract

Studies by Kendler and D'Amato (1955), Buss ( 1956), and Harrow and Friedman (1958) have attempted to assess the effects on concept formation of having intermittently reinforced irrelevant stimuli. These studies have concentrated on the possible role intermittent reinforcement might have in the observed superiority of reversal over nonreversal shifts and were designed to eliminate the possibility of intermittent reinforcement of a previously relevant dimension. On the other hand, Gormezano and Grant (1958) systematically varied the amount of intermittent reinforcement of an irrelevant dimension and assessed its effects on the attainment of the concept when in a nonreversal shift it subsequently became relevant. Buss (1953) conjectured that intermittent reinforcement of a previously relevant dimension would impede nonreversal shifts. The present investigation attempts to detail this relationship employing the procedure and analysis of Gormezano and Grant ( 1958). Specifically, it attempts to determine the difficulty of color or number sorting in the Wisconsin Card Sorting Test (WCST) (Grant & Berg, 1948) while intermittently reinforcing the previously relevant dimension of form 0%, 25%, 50%, or 75% of the time. PROCEDURE General procedure.-A detailed description of the procedure can be found in Gormezano and Grant ( 1958). In the present investigation eight decks of 48 cards were formed from WCST cards such that when S sorted on the basis of color or number he was intermittently reinforced O%, 25%, 50%, or 75% of the time on the irrelevant dimension of form. Each card contained one to four identical figures of a single color. There were four colors-red, green, yellow, and blue; and four figures-triangles, stars, crosses, and circles. Each card could therefore be sorted according to the color, form, or number of the figures. In the test situation a gray sorting tray with four double compartments was placed on a table before S. Four stimulus cards (one red triangle, two green stars, three yellow crosses, and four blue circles) were placed from left to right in the upper halves of the four double comparunents. Two decks of response cards, differing in composition, were placed in a partitioned box fastened to one of the legs of the table, facing E and out of S's view. S was instructed in a standard manner (Gormezano & Grant, 1958). E then selected a response card from one of the compartments and handed