with a completely visible weapon is compared with
performance in a condition with no weapon, but in
some studies researchers have manipulated the amount
of exposure time or the degree of visibility.
The primary dependent variable, witnesses’ memory
of the target’s appearance, has been measured using two
different methods. First, witnesses may attempt to
describe the target’s physical features (e.g., height, hair
color) and clothing by responding to open-ended or
multiple-choice questions. Many studies have demon-
strated that a weapon’s presence impairs the accuracy of
witnesses’ descriptions. A second method is to ask wit-
nesses to identify the target in a lineup. The weapon’s
influence on this less sensitive measure is weaker, with
a few experiments reporting null results.
Although memory of the target’s appearance is the
main interest in most studies, a weapon’s presence can
harm the ability to remember other aspects of the tar-
get as well. For example, witnesses exposed to a
weapon may find it more difficult than controls to
recall the semantic content of verbal statements made
by the target.
If witnesses in the experimental condition focus on
the weapon to a greater extent than controls focus on
the neutral object, one might expect this difference to
be revealed by eye movements and by memory for the
object. Consistent with these expectations, researchers
found that witnesses made more frequent and longer
eye fixations on an object held by a target in a slide
sequence if that object was a gun rather than a non-
weapon. Additionally, although only a few studies
have investigated memory for the object, those that do
exist generally indicate that witnesses can identify and
describe a weapon better than a neutral object.
Some researchers have used field studies rather than
lab experiments to explore the weapon focus effect,
usually by interviewing witnesses to actual crimes or
examining police reports. Some, though not all, of
these investigations have yielded null results. Perhaps
these findings are at odds with those obtained in lab
experiments because field studies are more realistic.
Alternatively, the discrepancy could be attributed to
field researchers’ difficulty in surmounting daunting
methodological obstacles. For example, determining
the accuracy of witnesses’ reports is problematic
because there is often no complete, objective record of
the scene they observed. Also, researchers must strug-
gle to eliminate potential confounds with the weapon’s
presence, such as exposure time, retention interval, the
witness’s vantage point, the perpetrator’s behavior, and
differences in police response (e.g., the police mightquestion witnesses to crimes involving weapons more
thoroughly than witnesses to weaponless crimes).
Nevertheless, field studies are a valuable complement
to lab research, and they offer the possibility of greater
ecological validity.
Two different explanations for the weapon focus
effect have been discussed in the literature. The first
interprets it as a consequence of the psychological
arousal or anxiety that the sight of a weapon is sup-
posed to create. The idea is that as a witness’s anxiety
rises to a point above the optimal level, attentional
capacity shrinks so that the witness focuses mostly on
central cues (e.g., the weapon, because it is the source
of the anxiety) at the expense of peripheral cues (e.g.,
the perpetrator’s clothing and facial features). This
hypothesis is contradicted by several findings:
Memory of the target is not affected by (a) the level of
threat that the armed target directs toward another per-
son, (b) the degree of threat associated with the object
held by the target, or (c) having a confederate holding
a syringe threaten the witnesses by telling them that
they would receive an injection as part of the experi-
ment. Moreover, the weapon focus effect occurs even
when witnesses rate their anxiety as low.
An alternative explanation proposes that weapons
seem unusual or unexpected within many contexts.
Furthermore, it is known that unusual objects within
visual scenes attract attention. Consistent with this
account, research has shown that an unusual object,
such as a stalk of celery or a toy Pillsbury doughboy,
can have the same impact on memory of the target as
a weapon.
One prediction that follows from the unusualness
explanation is that a weapon should fail to elicit the
typical weapon focus effect if it appears within a con-
text in which weapons would be expected. For exam-
ple, a gun held by a target at a shooting range would
not be out of place. A test of this prediction revealed
that, as hypothesized, a weapon focus effect did not
occur in that setting.
An interesting question with both theoretical and
practical implications concerns the mechanism by which
weapons attract attention. Specifically, do weapons cap-
ture attention automatically? If so, witnesses would have
relatively little awareness of and control over their atten-
tional focus. However, if the answer is no, potential
witnesses (e.g., bank tellers and convenience-store work-
ers) could perhaps receive training that educates
them about the weapon focus effect and teaches them
to watch the perpetrator rather than the weapon as a
crime unfolds. Recent data suggest that educatedWeapon Focus——— 863W-Cutler (Encyc)-45463.qxd 11/18/2007 12:44 PM Page 863