Encyclopedia of Psychology and Law

the presence of a weapon. Research has demonstrated

that these factors can produce general memory

impairments, but the effects are variable and unpre-

dictable with regard to specific individuals.

Approaches to the

Assessment of Lay Knowledge

Although the subject of scientific investigation of eye-

witness memory is more than 100 years old, it is pri-

marily the last 40 years of research that have provided

a substantive and reliable foundation of data. To assess

public beliefs concerning the eyewitness factors exam-

ined in this research, both directand indirectmethods

have been employed. For examples, the introductory

robbery scenario will serve. One factor that has long

been considered relevant to the reliability of eyewitness

identification is the correspondence between the race of

the witness and that of the suspect. Identification relia-

bility has often been found to be higher when both are

members of the same racial group than when the two

people belong to different racial groups—an outcome

called the “other-race” effect. Using the director survey

approach to the assessment of lay beliefs, respondents

might be asked to agree or disagree with statements

such as “People are better at recognizing members of

their own racial group than those of a different race” or

be asked to choose among a number of alternative for-

mats to the following statement: “When people are

asked to identify someone of a racial group different

from their own, they are just as likely(or more likelyor

less likelyor don’t know) to be correct as when the per-

son is of their own racial group.” On the other hand,

using an indirectapproach, respondents may receive a

brief written vignette in which the respective races of

the witness and perpetrator are either not mentioned at

all (a control condition), are described as being the

same, or described as different. The vignette may in

fact be a summary of an actual experiment in which

identification rates were examined as a function of vari-

ations in the racial similarity variable. After reading the

vignette, the respondents estimate the probability that

the witness’s identification decision is correct, an esti-

mate that is often called a “postdiction” in relation to

the actual experiment. Differences in the probability

estimates from participants who received the different

vignettes are taken to reflect public beliefs about the

direction and magnitude of the relationship between

witness-suspect race and eyewitness memory reliabil-

ity. If, for example, Simon Chung is Asian, but

the witnesses are Caucasian, juror beliefs about the

relevance of this distinction may be important to their

assessments of the identification evidence. Of course,

when compared with the effects of the variable on

actual identification accuracy in research experiments,

these response differences may reflect wholly erro-

neous beliefs.

These kinds of data from public samples will only

be helpful to a judge if he or she has a basis for assess-

ing the accuracy of the beliefs of survey respondents

and research participants and, by extension, the pub-

lic. Therefore, what is needed is a distillation of eye-

witness research that provides the “correct” answer

for each of the eyewitness factors present in a case.

These correct answers have been made available to

courts in two ways. In the first, survey researchers

explicitly compare the public survey and research out-

comes with their interpretations of what the scientific

research literature has revealed. In the second, the sur-

vey researchers instead compare their findings with

the results of surveys of “eyewitness experts” (them-

selves researchers) concerning the effects of variables

on eyewitness reliability. The most recent of the

expert surveys was completed in 2001 by Saul Kassin

and colleagues, who tabulated the survey responses of

64 experts to each of 30 propositions about eyewitness

factors including, for example, the effects of delay,

weapon presence, other-race identification, stress,

age, lineup construction techniques, and long term, to

name but a few. To date, no factor has received com-

plete unanimity from the experts as to its impact on

eyewitness memory. Instead, to determine what is cur-

rently “correct,” courts may look at general agreement

among experts or a consensus of opinion. For exam-

ple, of the 30 propositions presented to experts by

Kassin, only 16 achieved a consensus of 80% agree-

ment across experts. However, as a summarizing

statement, when the responses collected from lay par-

ticipants using both direct and indirect methods are

compared with the consensual opinions of the experts

about the factors, these comparisons frequently

demonstrate significant differences between the beliefs

of experts and those of members of the public.

Direct Methods

The earliest surveys were completed in the early

1980s and tested university students with multiple-

choice questions. The majority of participants did not

give the correct answer to most items, including the

effect of violence on recall accuracy, the relationship

between witness accuracy and confidence, memory

300 ———Eyewitness Memory, Lay Beliefs About

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