mation be coherent. For instance, if the face-recognition system
delivers information that a person is familiar, the person-file system
should try and retrieve a file for the person. If the animacy system
states that the person is moving in a goal-directed manner, the intu-
itive psychology system should produce inferences about what the
goals are, based on what information is accessible to the person. In
general, information from one system also helps correct or fine-tune
information from another one. If your person-file says that so-and-so
is an avid eater, the fact that they charge right across the room to the
kitchen is immediately translated in terms of goals (getting to the
[220] refrigerator) and mental representations (a hope that some delicacies
will be found in there).
This picture of the mind as orchestrating different sources of evi-
dence and different inference-systems would predict that incoherent
output from any system, or a lack of collaboration between these sys-
tems, will wreak havoc with ordinarily smooth operation. This is
indeed what happens in a variety of forms of brain impairment caused
by infection or stroke or head injury.
Prosopagnosia is one such pathology. Patients cannot recall who
people are by looking at their faces. It is not that their visual abilities
are generally impaired. Indeed, in all other visual tasks they can dis-
criminate between different shapes and images, and they can recall
associations between images. It is only faces that pose a special prob-
lem. Note that this deficit is generally limited to human faces. One
patient who became a sheep-farmer learned to identify the individual
"faces" of his own sheep. The impairment is not extended to all
aspects of persons, as voices and other contextual information are still
identified correctly. A spectacular demonstration of this limited
impairment is that patients are sometimes better than nonpatients at
particular tasks. For instance, faces seen upside-down are particularly
difficult for most people to identify. (To test that, open a newspaper
upside-down and look at the photographs of various politicians or
film stars. Chances are, you will not be able to recognize them till you
turn the paper right side up.) When those suffering from prosopag-
nosia are presented with several faces the right side up and asked to
match them to various upside-down images, they are sometimes bet-
ter than normal subjects at performing this task. Why is that? In nor-
mal subjects, face information is not handled by the same systems as
other complex visual shapes. It is sent to special brain areas. Now
these require a particular configuration of features (eyes above nose,
RELIGION EXPLAINED