Behavioral and neuroimaging evidence for a contribution of color and texture information to scene classification in a patient with visual form agnosia.
A common notion is that object perception is a necessary precursor to scene perception. Behavioral evidence suggests, however, that scene perception can operate independently of object perception. Further, neuroimaging has revealed a specialized human cortical area for viewing scenes that is anatomically distinct from areas activated by viewing objects. Here we show that an individual with visual form agnosia, D.F., who has a profound deficit in object recognition but spared color and visual texture perception, could still classify scenes and that she was fastest when the scenes were presented in the appropriate color. When scenes were presented as black-and-white images, she made a large number of errors in classification. Functional magnetic resonance imaging revealed selective activation in the parahippocampal place area (PPA) when D.F. viewed scenes. Unlike control observers, D.F. demonstrated higher activation in the PPA for scenes presented in the appropriate color than for black-and-white versions. The results demonstrate that an individual with profound form vision deficits can still use visual texture and color to classify scenes-and that this intact ability is reflected in differential activation of the PPA with colored versions of scenes.
Department of Psychology, The University of Western Ontario, London, Canada. jsteeves@uwo.ca
Jennifer K E
JK
Steeves
G Keith
GK
Humphrey
Jody C
JC
Culham
Ravi S
RS
Menon
A David
AD
Milner
Melvyn A
MA
Goodale
D000328:Adult; D000377:Agnosia / Q000503:physiopathology*; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology*; D003119:Color Perception Tests; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009949:Orientation; D020534:Parahippocampal Gyrus / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology