Effects of retention and intertrial intervals on proactive interference in the radial maze performance in rats

Abstract

The present study examined effects of retention and intertrial intervals on proactive interference in the eight-arm radial maze performance in rats. A trial consisted of a forced choice of four arms in a learning phase, retention interval, and a free choice among eight arms in a test phase. In Experiment 1, rats were given two daily trials with 10 s or 1 min. retention intervals between the learning and the test phases and with 5, 30, or 60 min. intertrial intervals. In the 1 min. retention condition, proactive inference indexed by decline in performance from the first trial to the second trial was observed regardless of intertrial intervals. In contrast, such decline in performance was not observed for all the intertrial interval conditions in the 10 s retention condition. In Experiment 2, rats were tested with a 1 min. retention interval and 5 or 120 min. intertrial intervals. Significant proactive interference was observed again for a 5 min. intertrial interval condition replicating the results of Experiment 1. In contrast, proactive interference was eliminated completely by lengthening the intertrial interval to 120 min. These results suggest that discriminability among memories in current and prior trials in terms of elapsed time is a determinant of proactive interference in the radial maze performance in rats.