Proactive inhibition in short-term memory

Abstract

Summary Two experiments investigating short-time retention of individual verbal items were performed. In the first, 72 Ss were tested for retention of each of a series of 12 CCC trigrams after intervals of 9, 18 and 27 sec. In the second, three groups of 24 Ss each were presented a series of 24 trigrams. For one group, retention of each item was measured after 3 sec, for a second group after 9 sec, and for the third group after 18 sec. At 3-week intervals Ss returned to learn additional series of trigrams which were tested at the remaining retention intervals. In both experiments, retention of the first trigram of a series remained constant over all retention intervals, while retention of the second trigram decreased as the length of the retention interval increased. Beyond the second trigram interpretation is complicated by the development of a practice effect. Results support the contention that PI operates in a similar fashion in short-term and in long-term memory and indicate that much of the forgetting observed in experiments using the Peterson technique of presenting and testing single verbal items can be attributed to the development of PI.