Encyclopedia of Psychology and Law

EYEWITNESSIDENTIFICATION:

GENERALACCEPTANCE IN THE

SCIENTIFICCOMMUNITY

This entry focuses on the degree to which experts

and others are persuaded that each of a number of fac-

tors influences the accuracy of eyewitness identifica-

tions. Supreme Court cases, among them United States

v. Amaral(1973) and Daubert v. Merrell Dow Pharma-

ceuticals (1993), have opened avenues of research

addressing how the influence of various factors on the

judgments of eyewitnesses is perceived by different par-

ties in the legal system. Reflecting their familiarity with

the literature, experts substantially agree on the extent to

which many variables influence identifications. Research

indicates that jurors do not agree with the experts on

many of these influencing factors. The use of legal

processes that will help jurors make better decisions in

cases that involve eyewitness identifications, such as

having experts testify in these cases, is thus justifiable.

Those who serve as law enforcement personnel show

unexpected patterns of agreement with experts, though

this tendency may change as a result of eyewitness

reform at the state level.

The Rationale

The issue of whether or not to allow scientific findings

into the courtroom continues to evolve in the United

States. The Supreme Court established the admissibil-

ity of eyewitness research in United States v. Amaral

(1973). The later Daubert v. Merrell Dow Pharmaceu-

ticals(1993) ruling established criteria that had to be

demonstrated for scientific testimony to be entered into

a trial. One of these criteria was that the basis for the

testimony should be generally accepted by the scien-

tific community. The Daubertdecision renewed inter-

est in what eyewitness factors are in fact generally

accepted by the scientific community. The first survey

focusing on the acceptance of eyewitness factors was

published in 1989. Research since then has greatly

expanded psychologists’ understanding of how mem-

bers of the scientific, legal, and lay communities accept

the findings reported in the eyewitness literature and

how this acceptance has changed over time.

It is now common for members of the legal psychol-

ogy community to distinguish between what are known

as system variables and estimator variables. System

variablesare those that are under the control of the legal

system and that can potentially bias an eyewitness dur-

ing the course of a criminal identification procedure. For

example, bias could enter into an identification proce-

dure through the techniques used to construct the crim-

inal lineup or by the use of leading identification

instructions given to an eyewitness. In contrast to sys-

tem variables,estimator variablesare those that encom-

pass eyewitness and crime scene characteristics that are

not under the direct control of the legal system.

Examples include the length of time afforded to the eye-

witness to view the crime or the presence of multiple

perpetrators at the crime scene. The provision of expert

testimony in a trial in which variables such as these are

relevant may serve to highlight potential biases in the

identification procedure that otherwise may have escaped

consideration by the judge or jurors.

The Opinions of Experts

Survey research demonstrates that many phenomena

experts overwhelmingly reported as being sufficiently

reliable to introduce under oath in 1989 continue to be

viewed as reliable influences on the accuracy of eye-

witness identifications more than a decade later. There

appears to be considerable consensus among experts as

to the reliability of the research evidence regarding the

wording of questions, the construction of lineups, and

the role of witnesses’ attitudes and expectations in

influencing their identifications, and on the relationship

between witnesses’ confidence in their identification

and their identification accuracy. Furthermore, experts

agree on the existence of other variables that reliably

influence eyewitness identifications, such as the rate at

which memories decay, the impact of exposure time on

memory and subsequent identifications, and the uncon-

scious transference of the memory of a familiar face

from one situation to another. Appreciable increases

were observed between 1989 and 2001 in the percent-

age of experts who agreed that human attention is likely

to be focused on a weapon rather than on a perpetrator’s

face (a weapon focus effect) and the impact of hypnotic

suggestibility. Both changes in consensus were attrib-

uted to the respective increases in interest and scholar-

ship on both topics in the years following the publication

of the first expert survey.

Later research would investigate the general accep-

tance of eyewitness factors not addressed in the original

1989 survey of experts. Attesting to the expanding cor-

pus of literature in the eyewitness field, a substantial

majority of experts agreed on the malleability of

eyewitness confidence, the suggestibility of the child

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