Aug 6, 2008

Memory Explanations (Part 2)

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Single-element familiarity

A deja vu experience may be triggered by one element of the present setting that is objectively familiar but unrecognized because it is experienced in a new and changed context. The familiarity elicited by the one unidentified object is misinterpreted as a response to the entire setting, resulting in deja vu. To illustrate, suppose that you visit a friend’s home for the first time, and the grandfather clock in the corner is identical to one in your aunt’s home. While you experience a familiarity reaction to this element, you are unable to connect your response to the “old” object and misattribute the familiarity to the entire new setting, resulting in a deja vu. This interpretation was proposed in earlier writings on the deja vu experience (Banister & Zangwill, 1941a; Boirac, 1876; Boring, Langfeld, & Weld, 1935; Bourdon, 1894; Conklin, 1935; Humphrey, 1923; James, 1890; Lapie, 1894; Leeds, 1944; Oberndorf, 1941) and has been resurrected in more recent speculation (Jordan, 1986; Levitan, 1969; Reed, 1979; Sno & Linszen, 1990; Zeidenberg, 1973).

MacCurdy (1925) called this phenomenon restricted paramnesia: the experience in which an element of the present setting is familiar but its prior identity is obscure. Banister and Zangwill (1941a, 1941b) used hypnotic suggestion to test this notion that a previously encountered but “forgotten” stimulus can be misidentified as familiar. They did not intend to create a deja vu, but wanted simply to evaluate whether participants could misattribute a hypnotically forgotten stimulus to the wrong setting. On the first day, participants studied pictures and odors during a normal waking state. On Day 2 they were hypnotized and presented with additional picture and odor stimuli, followed by a posthypnotic suggestion to forget these Day-2 stimuli. On Day 3, participants were tested with a mixture of new and old stimuli, and most participants (3 out of 5) misidentified some Day-2 stimuli as having been presented on Day 1. Although Banister and Zangwill (1941a, 1941b) emphasized that their study supported the possibility of such paramnesias, they noted that the relationship between their study and deja vu was “conjectural” and said that the results “throw little light on the origin of deja vu” (Banister & Zangwill, 1941b, p. 51). Despite this disclaimer, hypnotic procedures may hold some promise for an experimental paradigm to elicit déjà vu if accompanied by a sufficiently unique context within which to later experience the subsequently forgotten stimuli.

Also related to the single-element hypothesis is Whittlesea and Williams’s (1998) extension of the processing fluency theory of familiarity. Jacoby and Dallas (1981) demonstrated that when information is reexperienced, it is processed more easily and rapidly than in the first encounter, and this fluid reprocessing gives rise to a sense of oldness concerning the stimulus. Whittlesea and Williams argued that in the real world, the processing fluency basis of familiarity occurs primarily when the object or person is encountered in an unexpected context. In theory, meeting your spouse in your own kitchen should engender considerable processing fluency because of repeated exposures, leading to a strong familiarity response. However, this does not occur. In fact, such encounters curiously elicit no sense of familiarity. In contrast, if you unexpectedly spot your spouse sitting in the middle of your class as you lecture, this would arouse an intense and immediate sense of familiarity. Similarly, seeing your mail carrier at your front door arouses no sense of familiarity, but seeing him or her at the movie theater evokes a strong sense of familiarity due to the novel context (Reed, 1979). Applying this interpretation to deja vu, if an individual experiences a single familiar (but unrecognized) element in an unfamiliar context, the fluent reprocessing of this one element may elicit a deja vu experience specifically because the context is different.