Encyclopedia of Psychology and Law

often than when the suspect is placed between two

other lineup members that have a greater resemblance

to the suspect. This problem may arise even when the

average pairwise similarity rating across the lineup

members is high. Therefore, it is important that the

foils are selected for the lineup using the same crite-

ria. Another method for circumventing possible

popout effects is for researchers to systematically

rotate, or counterbalance, the position of the suspect

in the lineup across participants.

Counterbalancing the position of the suspect in

the lineup also controls for the possibility that the

decision standard varies along with the number of

faces that are viewed. This may be problematic espe-

cially in sequential lineups, in which the witness

views each face one at a time. In particular, there is

some evidence that the decision standard that wit-

nesses use in making a positive identification may be

lowered as they progress through the series of faces

in a sequential lineup. As such, innocent suspects

might have a higher probability of being chosen if

they are positioned later in the sequence, as opposed

to earlier.

Heather D. Flowe

See alsoClothing Bias in Identification Procedures; Facial

Composites; Identification Tests, Best Practices in; Lineup

Size and Bias; Mug Shots; Popout Effect in Eyewitness

Identification; Simultaneous and Sequential Lineup

Presentation; Wrongful Conviction

Further Readings

Gonzalez, R., Davis, J., & Ellsworth, P. C. (1995). Who

should stand next to the suspect? Problems in the

assessment of lineup fairness.Journal of Applied

Psychology, 80(4), 525–531.

McQuiston, D. E., & Malpass, R. S. (2002). Validity of the

mockwitness paradigm: Testing the assumptions.Law and

Human Behavior, 26(4), 439–453.

Tredoux, C. (2002). A direct measure of facial similarity

and its relation to human similarity perceptions.

Journal of Experimental Psychology: Applied,

8 (3), 180–193.

Tunnicliff, J. L., & Clark, S. E. (2000). Selecting foils for

identification lineups: Matching suspects or descriptions?

Law and Human Behavior, 24(2), 231–258.

Wells, G. L., Rydell, S. M., & Seelau, E. P. (1993). The

selection of distractors for eyewitness lineups.Journal of

Applied Psychology, 78(5), 835–844.

LINEUPSIZE ANDBIAS

A lineup is constructed by placing a person suspected

of committing a crime (the suspect) among a collec-

tion of innocent people (fillers). An eyewitness is

asked to identify the offender from this collection,

with a suitable admonition that the offender may not

be present. A properly conducted lineup can provide

evidence that the suspect is (or is not) the offender or

that the eyewitness does not have a reliable memory

of the offender’s identity. For this to be the case the

lineup must not be biased and it must be of sufficient

effective size.A lineup is biased when a witness with

a poor (or absent) memory is able to guess the identity

of the suspect at a rate greater than chance expectation

(one per lineup size). A lineup has a certain number of

members, including the suspect, and this is called the

nominal size.A lineup is unfair to the extent that it

contains fillers who are not plausible choice alterna-

tives to the suspect for a witness choosing randomly

or a witness with a poor (or absent) memory. The sus-

pect plus the number of persons who are alternative-

choice alternatives is called the lineup’s effective size.

Two basic rules govern the construction of eyewit-

ness identification lineups. First, the suspect in the

lineup should not “stand out” (be inappropriately dis-

tinct) from the other lineup members. Second, fillers

should resemble the suspect in important attributes

and should be appropriate-choice alternatives (i.e.,

witnesses who have a poor memory of the offender

should not be able to reject them).

Lineup Fairness Evaluation

To determine whether the two basic rules have been

adhered to, lineup evaluation research participants

who have not seen the offender are asked to guess

which lineup member is the suspect on the basis of a

brief physical description (e.g., the description origi-

nally given by the witness to the police) or with no

information at all about the appearance of the

offender.

Lineup Bias

Bias is bidirectional—it can make the suspect more

likely, or less likely, to be chosen by a witness who

has no or very little specific memory of the offender.

It is defined as a statistically reliable tendency for a

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