Retroaction and proaction in rats and guinea pigs

Abstract

Sixty-day-old rats and guinea pigs and 75-day-old rats were tested on a brightness discrimination task to ascertain whether or not they exhibited the effects of proaction and/or retroaction. Proaction was evaluated by requiring Ss to 1) acquire a discrimination to a criterion of 18 out of 20 responses; 2) learn its reversal to the same criterion; and 3) relearn the same problem to criterion. The corresponding control Ss rested while the experimental Ss acquired the first discrimination but learned the second and third problems in the same manner and to the same criterion as the experimental Ss. In the test for retroaction Ss were required to: 1) learn the discrimination to criterion; 2) learn the reversal of this discrimination to the same criterion; and 3) relearn the initial discrimination, again to the same criterion. Subjects in the corresponding control groups acquired the initial and final tasks to criterion while the experimental group Ss were learning their respective tasks, but rested during the second stage when Ss in the experimental group were learning the reversal. Twenty-four hours separated criterion performance and succeeding reversal tasks in all experimental and control groups. Analysis of variance on the percentage errors to criterion indicated that the 60-day-old rats exhibited proactive interference (PI) while the 75-day-old rats and the guinea pigs showed no PI effects. In contrast, all Ss displayed the effects of retroactive interference (RI). The results were discussed in terms of the relation of the two mechanisms to improvement in SDR learning as well as in terms of their relevance to other studies which tested for proaction and/or retroaction in non-human species.