Retrieval inhibition in directed forgetting and posthypnotic amnesia

In Experiment 1, subjects received either by word or by list directed forgetting or posthypnotic amnesia instructions. Recall and recognition performance of subjects who received directed forgetting instructions was consistent with previous findings reported by Basden, Basden, and Gargano (1993), with subjects who received by word instructions showing both recall and recognition deficits for to-be-forgotten items. By contrast, subjects who were given by list instructions showed recall but no recognition deficits, which suggests that although differential encoding underlies word method directed forgetting, retrieval inhibition underlies list method directed forgetting. Subjects who received posthypnotic amnesia instructions (irrespective of method of delivery used) showed recall deficits but no recognition deficits, which suggests that retrieval inhibition underlies posthypnotic amnesia. In Experiment 2, recognition scores were lower with public (oral) tests than with private (written) tests, and recovery was equivalent for to-be-forgotten and to-be-remembered items. The results are interpreted as inconsistent with the differential tagging mechanisms proposed by Huesmann, Gruder, and Dorst (1987).