Encyclopedia of Psychology and Law

criminal may influence a witness’s ability to later make

a correct identification of the criminal, research results

to do not support this assumption. Research has shown

that viewing mug shots has virtually no effect on later

identification accuracy from lineups.

Unconscious Transference

Unconscious transference from viewing mug shots

refers to the event in which an innocent lineup member,

who is also the only lineup member previously viewed

by the witness in a prior mug shot task, seems more

familiar than do the other lineup members because he

was viewed in the mug shots. The concern is that this

sense of familiarity on the part of the witness may lead

to an increased rate of selection of the (only) lineup

member who was seen previously in a mug shot task.

The phenomenon of unconscious transference has

likely plagued most adults at one time or another as evi-

denced in the common question, “Where do I know that

face?” For witnesses who view mug shots, followed by

a lineup that contains one person seen in those mug

shots and five photographs never seen before, they are

faced with a similar question. The correct answer is for

witnesses to say, “I saw that face in the mug shot task,”

and the erroneous conclusion is that the face is familiar

because it is the face of the criminal.

Support for unconscious transference from mug

shots is mixed, with only a few published studies find-

ing support for the effect. Researchers have manipu-

lated variables such as the number of mug shots viewed

(from 10 to more than 600) and the delay from viewing

the mug shots to the lineup task (immediately to several

weeks later) but have been unable to find a consistent

predictor of the unconscious transference effect.

Commitment

Commitment refers to the event when a witness selects

a (innocent) person from a mug shot task and then

selects the same (incorrect) person from a later lineup

procedure. Research on the commitment effect is con-

sistent in that it is relatively easy to produce and that

it has the largest negative impact on lineup identifica-

tion accuracy when considered with the other two

effects described above. In one research example,

almost two-thirds of witnesses who selected an inno-

cent person from a mug shot task went on to later

identify that same innocent person from a lineup. A

comparison group of participants who did not see mug

shots picked the innocent person at a rate of only 20%.

Procedural Matters

As with any identification procedure, there are numer-

ous ways that investigators could conduct the mug

shot task that may have differential effects on the out-

come. Some procedural variations that have been

examined include whether the photographs are sorted

by gender, age, race, and type of crime before view-

ing; the ideal number of mug shots to view; and

whether a computerized sorting system yields more

accurate identification results than do standard mug

shot methods.

In sum, mug shot research has not supported the

intuitive concerns that interference and unconscious

transference effects generate. Commitment to a photo-

graph, however, does seem to be a strong predictor of

identification errors from mug shot searching.

Regardless of the area of research described above, an

increase in real-world data obtained from field studies

will be highly beneficial and informative for future

mug shot research.

Jennifer E. Dysart

See alsoEyewitness Descriptions, Accuracy of; Eyewitness

Memory; Identification Tests, Best Practices in;

Unconscious Transference

Further Readings

Deffenbacher, K. A., Bornstein, B. H., & Penrod, S. D. (2006).

Mugshot exposure effects: Retroactive interference,

mugshot commitment, source confusion, and unconscious

transference. Law and Human Behavior, 30,287–307.

Dysart, J. E., Lindsay, R. C. L., Hammond, R., &

Dupuis, P. R. (2001). Mug shot exposure prior to lineup

identification: Interference, transference, and commitment

effects. Journal of Applied Psychology, 86,1280–1284.

Gorenstein, G. W., & Ellsworth, P. C. (1980). Effect

of choosing an incorrect photograph on a later

identification by an eyewitness. Journal of Applied

Psychology, 65,616–622.

McAllister, H. A., Stewart, H. A., & Loveland, J. (2003).

Effects of mug book size and computerized pruning on

the usefulness of dynamic mug book procedures.

Psychology, Crime & Law, 9,265–277.

MULTIPLE PERSONALITY DISORDER

See DISSOCIATIVEIDENTITYDISORDER

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