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By Bruce Bower
A brain-damaged man who can’t remember faces has nosed into a scientific debate
about how people learn to recognize
other complex objects. Deaf users of sign
language also have a hand in this dispute.
The man’s facial failures are one symptom of a general inability to perceive configurations of object parts, suggests a new
investigation led by psychologist Cindy
Bukach of the University of Richmond
in Virginia. The man stumbles at identifying not only people’s faces but also
computer-generated, three-part objects
called Greebles, even after extensive
training, Bukach’s team reports online
December 8 in Neuropsychologia.
Bukach and her colleagues studied LR,
a man who fails to recognize his daughter when shown a picture of her but
remembers distinctive facial features,
such as Elvis’ sideburns. Damage in a
car accident to a brain area just under
the right temple caused this condition,
“There are many ways in which face
recognition can be disrupted, but our
evidence shows that LR’s type of prosop-
agnosia impairs recognition of objects
with multiple parts, with faces as the
most obvious example,” Bukach says.
Relative positions of the eyes, nose and
If face recognition depends on a general
capacity for learning to recognize multi-
part objects, Duchaine holds, healthy
volunteers should recognize novel Gree-
bles as poorly as prosopagnosia patients
do at first but perform better than patients
after seeing lots of Greebles. LR’s Gree-
ble difficulties exceeded those of healthy
volunteers from the start, a sign of fun-
damental object-recognition problems
that make the results hard to interpret,
Duchaine contends. “These new results
don’t help us understand mechanisms
used for face processing,” he says.
A brain-damaged man who can’t recognize faces also fared poorly at learning
to distinguish computer-generated “Greebles” (such as these) from one another.
Each Greeble displays a distinctive configuration of three appendage types.