|
|
-
Study finds morphing eyewitness composites can catch criminals
A new study by Gary Wells, Distinguished Professor of liberal arts and sciences
and professor of psychology, and one of his Ph.D. students reports that
the morphing together of composites made by four individuals produces an
image that better resembles a target face than an individual composite,
as long as the morphed composites don't become too numerous.
"The problem with composites is that frankly, they don't look much
like the person," said Wells. "It's a difficult task for someone
to come up with a composite because we don't perceive faces piecemeal -
we don't store them in memory as individual facial features, such as the
nose, the eyes, or the mouth. Rather, the facial processing is holistic.
So in asking someone to come up with a composite, we're asking people to
do something that is totally unnatural."
Lisa Hasel, a doctoral student in psychology, joined with Wells to author
a research paper titled "Catching the Bad Guy: Morphing Composite Faces
Helps," which has been accepted for publication in Law and Human
Behavior, a professional journal. The study was awarded a national
prize by the Association for Psychological Science.
The researchers selected 16 target faces from a large database of facial
photographs. Each was of 19- to 23-year-olds that fell into four different
categories: four Asian females with long black hair, four Caucasian females
with short brown hair, four Caucasian males with short brown hair, and four
Caucasian males with medium-length black hair.
Sixteen Iowa State students participated in the composite generation phase
of the study, with 72 more participating in an initial attractiveness evaluation
phase, and another 60 in the similarity evaluation and second attractiveness
evaluation phase.
In the composite generation phase, participants were asked to look at one
of four different target faces in a specific category for one minute. After
each face was removed, they were asked to create four composites apiece
using the facial composite software called FACES. The four composites for
each face were then morphed together by an independent experimenter -- resulting
in 64 individual composites and 16 morphed composites.
Participants in the next phase rated the attractiveness of every face image,
comparing the overall attractiveness of the three face image categories
-- photos of target faces, composites, and morphs. The morphed composites
were found to be the most attractive of the three.
The final group also rated the attractiveness of the face images, as well
as the similarity of the individual composites and morphs to both the target
and non-target faces. Upon completing their ratings, they were asked to
select from a face array, which included the target face, which face looked
the most similar to the individual composites or morphs. The morphs produced
a higher target-preference rate (47.7%) than did individual composites (35.2%).
"Does morphing four composites into one represent a specific person
better than individual composites? The bottom line is that the answer is
‘yes,'" said Wells.
Wells reports two side-effects associated with the conclusion:
*The morphed image was found to be more "attractive" than the
individual target faces.
*The morphed image better resembles the intended target face, but also better
resembles other faces who are not the intended target.
-
Gary Wells
Around LAS
October 2-15, 2006
|
|
