effect of witness confidence. When experts testify for
both sides, however, jurors appear to become skepti-
cal of all eyewitness testimony, including identifica-
tions made under relatively good conditions.SScciieennttiiffiicc aanndd SSttaattiissttiiccaall EEvviiddeennccee
Finally, it has been found that jurors can have par-
ticular difficulty with certain types of complex evi-
dence, such as statistical, scientific, or other forms of
expert testimony. On the one hand, expert evidence
often proves helpful to juries—for example, helping
them better evaluate other evidence, such as eyewit-
ness testimony or confessions (see above). In addition,
there is evidence that jurors carefully evaluate such
expert testimony, approaching expert witnesses with
some skepticism and working to evaluate both the
experts (e.g., their credentials and motives) and the
substantive testimony. On the other hand, it has been
found that jurors sometimes have difficulty in under-
standing and using such evidence properly. For exam-
ple, there is evidence that jurors are not skilled at
identifying flaws in the design of scientific research
studies and may not discount the value of such
research appropriately. Studies with confounding vari-
ables, missing control groups, problems with the valid-
ity of measures, and the opportunity of experimenter
demand are as influential as better-designed studies,
and witnesses presenting such flawed research are not
seen as any less credible than witnesses presenting
studies without such flaws. Similarly, interviews with
jurors as well as experimental studies have shown that
jurors experience difficulty in reasoning about and
making inferences from statistical evidence, such as
probability estimates and information about popula-
tion base rates. Recent research, however, suggests that
improved judicial instructions may help jurors better
understand scientific testimony.Civil Decision Making
Civil juries in particular have been criticized as unpre-
dictable, arbitrary, biased against plaintiffs, and prone
to making large damage awards. Data from actual
cases, however, provide little evidence of juries that
are out of control; most jury awards are modest.
However, while jury damage awards are appropriately
influenced by legally relevant factors, they can also be
highly variable, such that different amounts are
awarded in cases involving what seem to be similarinjuries. In addition, studies have found that juries
tend to overcompensate small injuries but undercom-
pensate large injuries. Moreover, there is evidence that
for noneconomic damages, such as damages for pain
and suffering, and for punitive damages, jurors have
some difficulty in translating their judgments into dol-
lar figures and can be influenced by cognitive biases
such as anchoring.
Concern is often expressed that juries are biased in
favor of plaintiffs and against defendants, particularly
those defendants with “deep pockets.” However, there
is evidence that jurors are relatively skeptical of plain-
tiffs and their claims. In addition, there is little evi-
dence that the wealth of the defendant influences
jurors’ liability determinations or their compensatory
damage awards. In contrast, however, corporate
defendants do seem to be held to a higher (“reason-
able corporation”) standard of conduct than are defen-
dants who are individuals.Jury Instructions
The primary way in which juries are schooled in the
requirements of the law is through the legal instruc-
tions that trial judges give them to guide their deci-
sions. These instructions explain the jury’s role, inform
the jury about the legal rules that govern the case that
it is to decide, define the standard and burden of proof,
and define the possible alternative verdicts available to
the jury. Typical instructions focus on stating the law
precisely rather than on comprehensibility; contain
many legal terms of art; and consist of lengthy, com-
plex sentences. Perhaps not surprisingly, therefore, a
large body of research has demonstrated that while
jurors perform relatively well at understanding and
remembering the factual evidence presented at trial,
they often have difficulty in understanding, remember-
ing, and applying these legal instructions. For exam-
ple, jurors have particular difficulty in understanding
the “beyond a reasonable doubt” standard in criminal
cases, the “negligence” standard in civil cases, and
legal terms such as “aggravation” and “mitigation” in
capital punishment instructions. Similarly, typical
instructions limiting the use of particular evidence or
indicating that particular evidence is to be ignored are
poorly understood.
Significantly, there is evidence that the comprehen-
sion of and ability to follow instructions is improved
when instructions are rewritten following the basic
principles of psycholinguistics. Removing legal jargon,Jury Competence——— 403J-Cutler (Encyc)-45463.qxd 11/18/2007 12:43 PM Page 403