Why Do People Make Errors in Eyewitness Testimony? • 231If the participants in both groups had been tested on their knowledge of the video
at this point, which group do you think would remember more? Although this was not
determined in the experiment, it is likely that the test group would have remembered more
because of the practice provided by being tested. This is what we would predict based on
the results of experiments on the testing effect described in Chapter 7 (page 180), which
showed that taking tests after studying material increases memory for that material.
Instead of testing participants at this point, Chan presented an 8-minute audio that
described some of the events in the TV program. Some events were described accurately,
but some misinformation items differed from what happened in the video. For example,
in the video the terrorist knocked out the fl ight attendant with a hypodermic syringe,
but the misinformation item in the audio stated that the terrorist used a chloroform
pad. The procedure in this part of the experiment is therefore similar to the procedure
in the misinformation studies we described earlier. Finally, all participants took the cued
recall test (the same one that the test group had taken earlier).
Imagine that you are one of the experimenters waiting for the results of the recall
test. Which group would you predict would do better on the recall test—the test group
or the no-test group? Stop for a moment and think about this before reading further.
Did you come up with an answer? Using common sense, and perhaps your knowl-
edge of the testing effect, your answer might be that the test group, which took the recall
test before being exposed to the misleading information, would perform better. However,
the result, shown on the right, indicates that the opposite occurred. The number indicates
the percentage of incorrectly described items (the misinformation items) from the video
that participants indicated were in the original program. The test group said “yes” incor-
rectly to 50 percent of these items, compared to 30 percent for the no-test group.
This result, which Chan calls the reverse testing effect, shows that taking a recall
test right after seeing the program increased participants’ sensitivity to the misinforma-
tion. There are a number of possible reasons for this result. One reason is related to
the reconsolidation effect we described in Chapter 7 (page 195). Remember that reac-
tivating a memory can make it susceptible to being eliminated or modifi ed. This can
strengthen memories if the person is exposed to correct information (as might occur
when reviewing information as you study for an exam), but it can distort memory if the
person is exposed to different information (as occurs in the misinformation procedure).
According to this idea, testing that reactivates memory for an event makes the
memory vulnerable to change. This mechanism would explain Chan’s result, and may
also help explain the experiment by Lindsay, in which participants who looked at a
picture of their grade school class were more likely to be infl uenced by misinforma-
tion (see page 226). Perhaps when Lindsay’s participants looked at the class picture,
their memories were reactivated and so became more vulnerable to being affected by
misinformation. (Review the description of Hupbach et al.’s experiment described on
page 197 in Chapter 7. Can you see the parallel between the Hupbach experiment and
this explanation of Lindsay’s result?)
Chan also describes other possible mechanisms, but the main point for our pur-
poses is that this effect occurs. The main reason this effect is important is that after
witnessing a crime the witness is typically questioned about it, either at the scene or
afterwards. This is, of course, necessary, but according to the results of Chan’s experi-
ment, thinking about this information makes it vulnerable to being changed by sugges-
tion, misinformation, or other postevent experiences.WHAT IS BEING DONE?
The fi rst step toward correcting the problem of inaccurate eyewitness testimony is to recog-
nize that the problem exists. This has been achieved, largely through the efforts of memory
researchers and attorneys and investigators for unjustly convicted people. The next step is
to propose specifi c solutions. Cognitive psychologists have made the following suggestions:- When asking a witness to pick the perpetrator from a lineup, inform the witness
that the perpetrator may not be in the particular lineup he or she is viewing. As
we have seen from the results of a number of studies, witnesses will usually pick
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