Arguments against a strong CA relationship have,
however, been much more consistently advanced, with
these views reinforced by demonstrations of overcon-
fidence in various domains of human judgment. Some
of the grounds for questioning a meaningful CA rela-
tionship include our (a) inability to review all factors
that should shape confidence; (b) tendency to focus too
heavily on confirmatory evidence for a decision;
(c) problems with translating subjective judgments of
confidence into some kind of numerical confidence
value; (d) reliance on cues to confidence that, while
sometimes veridical, may also be misleading (e.g., a
face in a lineup may seem very familiar not because it
is that of the offender but because it had been seen in
the context of the event previously, or witnesses may
infer that the face in the lineup that seems most famil-
iar must be the offender because they got an excellent
view of the offender at the crime); and (e) almost
inevitable exposure to postidentification social influ-
ences that produce malleable confidence judgments.Confidence-Accuracy Correlation
For some time the dominant view among eyewitness
memory researchers has been that postidentification
confidence does not provide a particularly informative
guide to the likely accuracy of an identification deci-
sion. It has been generally accepted that the CA rela-
tionship is best described as lying between weak (at
worst) to modest (at best) for witnesses who make a
positive identification (i.e., choosers) from either a
culprit-present lineup or a culprit-absent lineup—
indicated by CA correlations that seldom exceed 0.3—
and virtually nonexistent (correlations around 0) for
witnesses who reject either of these lineups (non-
choosers). Note, however, that the correlations for
choosers have been shown to be higher when, for
example, (a) the encoding and test stimuli have been
allowed to vary as they do in the real world, (b) stimu-
lus encoding conditions were optimal, and (c) wit-
nesses were encouraged to be self-aware with respect
to their preidentification decision behaviors by being
asked to view a video of their own identification deci-
sion before giving a confidence assessment.
Although the finding of a modest CA correlation is
clearly a reliable one, it does not provide the complete
picture regarding the CA relationship. This requires
supplementing the correlation between confidence and
the identification decision outcome (accurate, inaccu-
rate) with an examination of other characteristics ofthe CA relation—specifically, an examination of
CA calibration and patterns of overconfidence/
underconfidence. The correlation coefficient reflects
the variance in decision accuracy associated with vari-
ations in confidence. For the eyewitness identification
paradigm, which typically involves a witness making a
single identification decision, this therefore reflects
variance explained at the level of the group but is not
informative about the likely accuracy of a witness’s
decision accompanied by a specific level of confidence
(e.g., 70% confident or 90% confident). Information
about the latter is, however, obtainable by applying the
calibration approach to the examination of the CA
relationship and, since the late 1990s, a number of
studies of the CA relationship in eyewitness identifica-
tion have used this approach.Confidence-Accuracy Calibration
At a conceptual level, the procedure is quite simple,
with the proportion of accurate identification decisions
determined for each level of identification confidence
(10%, 20%, etc.). This provides the basis for plotting a
calibration curve and the derivation of calibration,
overconfidence/underconfidence, and resolution statis-
tics. Inspection of the calibration curve provides a
direct indication of the levels of identification accuracy
expected in association with varying degrees of confi-
dence; for example, judgments made with 100% con-
fidence might be characterized by 85% accuracy.
Perfect calibration is, of course, characterized by 0%
accuracy at 0% confidence, 10% accuracy at 10% con-
fidence, right through to 100% accuracy at 100% con-
fidence. Any departure from perfect calibration is not
only illustrated by comparing the obtained and ideal
calibration curves but can also be captured in a cali-
bration statistic (varying from 0 to 1, with 0 indicat-
ing perfect calibration) and an overconfidence/
underconfidence statistic (varying from 0 ± 1, with
increasing positive and negative departures from 0
denoting increasing overconfidence and underconfi-
dence, respectively). In addition to the guide provided
by the calibration procedure to the likely accuracy of
identification decisions made with particular levels of
confidence, it also provides a resolution statistic that
(like the correlation coefficient) indicates variance in
decision accuracy associated with confidence.
A number of studies have now applied the calibra-
tion approach to the study of the CA relation within
the eyewitness identification paradigm. While theseConfidence in Identifications——— 139C-Cutler (Encyc)-45463.qxd 11/18/2007 12:41 PM Page 139