Functional magnetic resonance imaging (fMRI) has revealed distinct brain areas responsive to faces (the fusiform face area or FFA) and attributes of scenes such as houses (the parahippocampal place area or PPA).
The Fusiform
Face Area and the Parahippocampal
Place Area
When an image of a face is presented to one eye and an image of a house to the other, our perception alternates between the two images - this is the phenomenon of binocular rivalry.
Left Eye
Observer Perceives
Right Eye
When
activity in the FFA and PPA is measured using fMRI it is found to correlate
with the subject's perception. When the percept switches from face to
house, activity in the FFA drops and activity in the PPA rises. When the
percept switches back from the house to the face, activity in the PPA
drops back down and activity in the FFA rises back up. All this time there
is no change in the stimuli being presented to the two eyes, so what we
have is a correlation between brain activity and perception in the absence
of any external changes.
