The Importance of
Mathematical Models
Why is it important to develop mathematical models
for eyewitness identification? Mathematical and com-
putational models can be particularly useful when the
behavior of interest arises from the confluence of many
complex, underlying processes. Eyewitness identifica-
tion decisions certainly fit that description. For exam-
ple, a witness’s identification accuracy may change
with the passage of time, not only because information
is lost from memory but also because the witness may
make adjustments in his or her decision processes (e.g.,
lowering the decision criterion as match values drop
due to the loss of information over time).
Also, models provide a way of evaluating ideas
within a common framework. As noted earlier, when
a witness is given biased instructions, the change in
the witness’s willingness to make an identification
could be due to a change in decision criterion or a
change in the balance of absolute and relative infor-
mation used to make the decision. Competing expla-
nations can be compared within the model to see
which explanation gives the best account of the exper-
imental results.
Models such as the WITNESS model can lead to
new discoveries and new ideas and can challenge
well-accepted views. Such models generate quantita-
tive predictions that can be compared with data,
allowing precise specification, clear predictions, and
straightforward evaluation of the model. When mod-
els are compared in this way, theories that seem intu-
itively plausible sometimes fail quite badly and
theories that seem intuitively wrong sometimes fit
data quite well.Steven E. ClarkSee alsoEyewitness Memory; Instructions to the Witness;
Lineup Size and BiasFurther Readings
Clark, S. E. (2003). A memory and decision model for
eyewitness identification. Applied Cognitive Psychology,
17,629–654.
Hintzman, D. L. (1991). Why are formal models useful in
psychology? In W. E. Hockley & S. Lewandowsky (Eds.),
Relating theory and data: Essays on human memory in
honor of Bennet B. Murdock(pp. 39–56). Hillsdale,
NJ: Lawrence Erlbaum.Wells, G. L. (1984). The psychology of lineup identifications.
Journal of Applied Social Psychology, 14,89–103.
Wells, G. L., & Olson, E. A. (2003). Eyewitness testimony.
Annual Review of Psychology, 54,277–295.WITNESSPREPARATION
The term witness preparationrefers to any type of
advice or training given to someone who is going to
give sworn testimony with the intention of helping
improve the quality of their testimony. All persons
who might testify in court are potential candidates for
witness preparation, including civil and criminal case
defendants, plaintiffs, victims, experts, eyewitnesses,
and other lay witnesses. Witness preparation may be
used to prepare witnesses to testify during trial, but it
is also used to prepare them to testify in pretrial depo-
sitions and hearings. Witness preparation is carried
out by attorneys in most cases, but psychologists,
communication specialists, acting coaches, and other
consultants assist attorneys in preparing witnesses in
some cases—especially high-profile cases.
The two main goals of witness preparation are to
educate witnesses about the testimony process and to
improve their communication skills. Whether carried
out by attorneys, psychologists, or other consultants,
witness preparation can be thought of as a behavioral
intervention designed to improve communication
skills and foster an appropriate level of confidence
about testifying. This entry provides an overview of
the techniques used to prepare witnesses to testify in
court and a summary of the small, but generally sup-
portive research literature examining its use.Witness Education
Most people who undergo witness preparation training
are novice witnesses who have little or no experience
testifying. Sometimes, these witnesses know little
about the nature and process of courtroom testimony,
such as where they will sit in the courtroom, who will
ask them questions, and what the questions will be
like. These circumstances often contribute to feelings
of anxiety and fear in novice witnesses. Research sug-
gests that one way to reduce witnesses’ feelings of anx-
iety about testifying is to educate them about the
testimony process by having them participate in a tes-
timony simulation. A testimony simulation can also be866 ———Witness PreparationW-Cutler (Encyc)-45463.qxd 11/18/2007 12:44 PM Page 866