Retrieval-Induced Forgetting: A Proposed Mechanism for Intrusive Reexperiencing in Posttraumatic Stress Disorder
Bittinger, Joyce N.
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Prominent theories of PTSD implicate the disorder-specific process of memory fragmentation as a key mechanism underlying intrusive reexperiencing. Across methods used to explore fragmentation in PTSD, we see these theories do not hold up well as studies fail to show a compelling association between fragmentation and PTSD. In the current study, an alternative retrieval inhibition explanation of intrusions was explored, using the distressing film paradigm to examine memory performance, fragmentation, and intrusion in an analogue undergraduate sample. Using a modified between-subjects retrieval practice paradigm, 165 participants watched a distressing film and were then randomized into one of three conditions; a retrieval practice condition, a no-retrieval practice condition, and a presentation only condition. As predicted, intrusion for film stimuli differed between groups showing both facilitation effect of practice and the RIF effect, demonstrating that the manipulation successfully shifted unintentional recall of memory for the film stimuli. Intentional free recall also differed by group. A facilitation effect was seen; practiced material was recalled more frequently than unpracticed material. However the RIF effect was not observed. Rather than events from the film being recalled more frequently by participants who did not engage in retrieval practice of the film stimuli, as compared to recall for unpracticed events from the practice condition events, the opposite was true. Unpracticed events in the practice group were recalled more frequently than the same events in the no-practice group. The pattern indicated that increased contact with the film appeared to facilitate recall of the unpracticed events and that retrieval practice facilitated unpracticed events beyond that of mere increased contact. Findings are related to boundary conditions of RIF. As the current study proposed an alternative mechanism to fragmentation, the study was designed to examine the role of retrieval on fragmentation indices as well as the association of fragmentation and dissociation on subsequent intrusions. Neither construct was associated with intrusions in the current study; a finding that further challenges fragmentation theories as well as the dissociative encoding hypothesis of PTSD. The need for further study of post-trauma processes, such as differential retrieval, is discussed.
- Psychology