Implicit.memory.versus.false.memory.pdf

Implicit Memory versus False Memory

Julian Missig

85-445 Memory Phenomena & Mechanisms

3 May 2005

Background

An unfortunate fact of life is that a person in a position of power does not always have

the best interests of those under him or her in mind. A particularly unfortunate example

is a therapist who would rather believe that a young woman was raised in a satanic cult

and convinces his patient that this really is what happened, despite a complete lack of

evidence (Schacter, 1996). This example is only one of many; there are many cases of

patients recovering memories with the help of therapists only to later discover that

these “memories” were not at all true. Yet these patients completely believed those

memories until the mountain of evidence against them simply grew too big. It is

because of these cases that researchers became interested in how the mind comes distort

real memories in order to accommodate false ones.

Even though Freud and others have studied repressed memories, the study of

false memories as a cognitive process has only recently come to the attention of

researchers. Schacter (1996; Loftus, 1993 tells a similar tale) reviews one account of the

history: In 1990 George Franklin was convicted of the 1969 homicide of his daughter’s

friend Susan Nason. The conviction was based almost entirely upon repressed

memories which his daughter claimed to have recovered. Regardless of whether or not

the allegations were true, many questions arose as to whether these memories were in

fact real. Even if the memories were not real, Franklin’s daughter truly believed them to

be. This case sparked many—by 1992 the number of lawsuits based upon the recovery

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of repressed memories had grown to such a great number that parents joined with

professionals to form the False Memory Syndrome Foundation. Within four years of its

founding, the Foundation had been contacted by 17,000 people about repressed

memory cases (Schacter, 1996).

In discussing the recovery of repressed memories, several cognitive questions

arise: Is it even possible to repress a memory of a tragic event? If so, is it possible to

recover those memories at a much later date? How do you tell the difference between a

truly recovered memory and a memory which was merely suggested by the process of

attempted recovery? It is this last question which I will investigate.

False Memory

Roediger and McDermott (1995) describe a method of creating false memories known as

the Deese-Roediger-McDermott method. One simply presents a list of semantically-

associated words—for example, a list of words relating to “needle”—and then asks the

participant whether they remember seeing words in the list they were presented.

Participants are rather likely to report having seen the word “needle” even though they

did not actually see that word. This is technically a form of false memory, but it is not

quite implanting an entire false episode simply by describing it. I believe that to further

investigate the “recovered” memory situation, we need to look at memories which were

introduced in ways similar to what happens in the court room.

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Wells and Bradﬁeld (1998) presented participants with a grainy video of a man in a

Target Store which was used as evidence in an actual murder case. Participants were

only informed that the man in the video murdered someone after viewing the video.

Participants had to choose the suspect from a set of lineup photos. The photo of the real

suspect never appeared in the lineup. After participants made an identiﬁcation they

were randomly assigned to receive conﬁrming feedback (“Good. You identiﬁed the

actual suspect”), disconﬁrming feedback (“Actually, the suspect was number __”), or no

feedback. The fact that participants were not told that the suspect may not actually be in

the lineup (which occurs in real eyewitness lineup identiﬁcations) combined with the

fact that the actual suspect was not in the lineup led to a 100% false identiﬁcation rate.

After the feedback was given and a short time had passed, the participants were

asked a series of questions about their conﬁdence at the time of identiﬁcation, how good

of a view they had of the suspect’s face, how long it took them to identify the suspect,

and other similar questions. Participants had more conﬁdence in their identiﬁcation

when conﬁrming feedback was given, while disconﬁrming feedback did not lower

conﬁdence very much at all. Further experiments corroborated this and demonstrated

that the participants were not even accurate in reporting their own ability to identify the

suspect —for example, some participants believed they had instantly identiﬁed the

suspect with full conﬁdence. The experimental method used by Wells and Bradﬁeld

(1998) as described above has come to be known as the False Feedback paradigm.

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Implicit Memory

It is possible that people with implanted false memories may still retain implicit, or

unconscious, memory of the real events which happened (Schacter, 1996). This

possibility dates all the way back to Freud and Breuer, who initially believed that the

fears, images, and anxieties that their patients exhibited in response to certain stimuli

were the result of an implicit memory for an event which really happened—which the

patients had blocked out or covered up in their explicit memory. Freud later abandoned

this view in favor of the possibility that these implicit memories were the result of

dreams and the unconscious, but today Terr and other therapists still believe that

implicit memories may be retained (Schacter, 1996).

While not directly implicit memory, one implicit learning paradigm which

involves visual memory is Contextual Cueing. Chun

and Jiang (1998) presented participants with a visual

search task, such as the one in Figure 1 where

participants must ﬁnd the rotated “T” among rotated

“L”s. The participants would then press one key if the

Figure 1. Typical Contextual

Cueing display

“T” was facing right, and another if it was facing left.

Half of the spatial conﬁgurations were essentially random and were never

repeated again, but the other half of the displays were repeatedly presented, spaced

apart by many trials. The participants were not aware of the repetition (even in post-

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