fact, the house in the film was white). The subjects then answered questions
about the film (e.g., ‘‘What was the color of the house?’’ ). The interesting find-
ing was that subjects who were biased by the incorrect detail, and therefore
gave the wrong answer (e.g., ‘‘The house was brown’’), were more confident of
their wrong answer than were the subjects who were not given the misleading
detail and so usually gave the correct answer (e.g., ‘‘The house was white’’).
People may become confident of their inaccurate memories when some inac-
curately remembered piece of information is nevertheless consistent with the
gist of some previously presented information. For instance, Roediger and
McDermott (1995; see also Deese, 1959) presented subjects list of words (e.g.,
bed, rest, awake) for which every word on a list was related to a target word
(e.g.,sleep) not presented on the list. Later, on tests of recall and recognition,
subjects remembered that the target words (e.g.,sleep)wereonthelistaboutas
often and with about the same confidence as they remembered the words that
were actually presented on the lists. Moreover, the greater the number of re-
lated words presented on the list, the more likely subjects were to recall or rec-
ognize the target word not presented on the list (Robinson & Roediger, 1997).
Presumably, the tendency to think of the target word when studying the list
created a false memory for that target word that seemed as real to subjects as
their memories of actually presented words.
The Overlap Principle
The fact that memory makes use of reconstruction strategies, such as relying on
one’s current beliefs to deduce past beliefs, means that remembering is often
inaccurate. But recollections of the past are not inevitably inaccurate. The study
of memory has established that memory of an event is more accurate when the
environment at the time of recollection resembles the environment of the origi-
nally experienced event (Begg & White, 1985; Guthrie, 1959; Tulving, 1983;
Tulving & Thomson, 1973). This principle may be called theoverlap principle—
people’s memory for a past event improves to the extent that the elements of
the recollection environment overlap with the elements of the past event. By
environment, I mean a person’s cognitive and emotional state, as well as the
person’s physical environment. The overlap principle also goes by the name of
encoding specificity, to emphasize that how an event is processed or ‘‘encoded’’
will determine what kinds of cues will later be effective at promoting memory
for the event (Tulving & Thomson, 1973).
Experimental Evidence for the Overlap Principle A good experimental demon-
stration of the overlap principle comes from research designed to help eye-
witnesses more accurately remember crimes and accidents. Courts of law place
strong emphasis on eyewitness accounts when assessing responsibility and
punishment. Yet people often have a hard time remembering important details
of crimes and accidents they have witnessed, a point I used earlier to illustrate
the concept of reconstruction in memory. A variety of research suggests that
eyewitness memory improves if the context surrounding the event is reinstated
(see Geiselman, 1988).
Cutler and Penrod (1988; see also Geiselman, Fisher, MacKinnon, & Holland,
1985) had subjects view a videotape of a robbery and a few days later pick out
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