Apparent Amnesia : interidentity memory functioning in dissociative identity disdorder

Abstract

Dissociative identity disorder (DID) is characterized by the presence of two or more distinct identities or personality states that recurrently take control of the individual s behavior. Between 95 and 100 % of DID patients report experiences of blank spells for periods of time when other identities are in control of their behavior. In this thesis, the fundamental question of whether objective evidence for the reported interidentity amnesia in DID can be found under rigorous experimental conditions was addressed. The thesis provides a systematic exploration of interidentity amnesia in DID for both neutral as well as trauma-related information on a variety of different encoding and retrieval tasks. In order to provide an unequivocal measure of memory performance, much attention was given to the use of tasks on which simulation of amnesia-symptoms is expected to be very difficult. Also, a control group instructed to simulate DID was included. The conclusion that can be drawn is that, the patients results did not indicate amnesia but transfer of information between the identities tested. How can the discrepancy between patient s reports of interidentity amnesia and the lack of objective test results be reconciled? The DID patients experience of amnesia may result from a faulty cognitive evaluation of a recollection after intact memory retrieval. Because patients are convinced of having different identities, they construct an image of their memories being compartmentalized in their separate identities. This distortion may lead them not to use some retrieved memories, that they are convinced belong to other identities. Deciding not to use correctly retrieved information then lies at the basis of their amnesia-like behaviors. These behaviors may thus reflect the patient s appraisal of retrieved memories as ego-dystonic or ego-syntonic rather than a memory encoding and/or retrieval impairment.