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Interpersonality Priming in People With Dissociative Identity Disorder?
Article SummaryInterpersonality disorder is one hallmark of dissociative identity disorder (DID). The different identities do not have access to the specific thoughts, feelings, and actions of the other identities. Psychologists are very interested in the memory deficits of people with DID. At issue is whether the different identities in people with DID share implicit memories even though they do not share explicit memories. Past research has shown that some people with DID do have intact implicit memory, as demonstrated by priming studies. This apparent sharing of implicit memory, or interpersonality priming, is the opposite of interpersonality amnesia, demonstrated by a lack of sharing of explicit memories between identities. Eich, Macaulay, Loewenstein, and Dihle hypothesized that interpersonality priming is a necessary but not sufficient condition for demonstrating that different identities share implicit memories. They argued that interpersonality priming would be apparent only when the priming task tapped general information but would not occur on tasks tapping identity-specific information. They developed two types of tasks that differed in terms of how much prior experience could be used to complete the task. One task was picture completion: A person is shown a set of cards containing fragments of a line drawing of some common object, such as an airplane. The first card has just a little bit of the drawing, the second card a bit more of the drawing, and so on, until the last card has a completed drawing of the object. The goal of the task is to correctly identify the object after having seen the fewest number of cards. Priming is demonstrated if a person can name the picture more rapidly after having encountered the word in a different context than if the person had not encountered the word. Interpersonality priming would occur if one identity could name the picture more rapidly when another identity had previously encountered the word. The other task was stem completion: A person is shown a word stem, such as app-, and is asked to free associate and say the first word that comes to mind that completes the stem, such as apple or appendix. Priming is demonstrated if a person completes the stem with a word that he or she has encountered in a previous context. Interpersonality priming would occur if one identity completed the stem with a word that another identity had encountered. Eich et al. argued that interpersonality priming would more likely occur on tasks where there is only one correct response, as in the picture completion task, but not on tasks where a variety of idiosyncratic answers can be made, as in the stem completion task. Eich and his colleagues tested 9 people with DID. Each of these people could alternate between two identities but who did not claim to have any conscious awareness of the other's experiences. They had one identity (P1) rate words on imageability and pleasantness. The other identity (P2) then did the picture completion and stem completion tasks. Some of the words in these tasks were words that P1 had rated and some were not. P2 also rated a new set of words. Finally, P1 completed the picture and stem tasks, with some of the same words that P2 had rated. As they had predicted, Eich et al. found interpersonality priming only on the picture completion task, for which only one correct answer was possible. They found interpersonality amnesia on the stem completion task, in which participants could free associate an answer. Eich et al. concluded that the amount of interpersonality "leakage" in apparent implicit memory between identities in people with DID is due to identity-specific effects; if different identities could bring their own experiences to the task, there was no interpersonality priming but if the task tapped general semantic knowledge, interpersonality priming did occur. |