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Sensitivity to identity and 3-dimensional structure among temporal cortical cells selectively responsive to faces
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SENSITIVITY TO IDENTITY AND 3-DIMENSIONAL STRUCTUREAMONGTEbIPORAL CORTICAL CELLS SELECTIVELY RESPONSIVE TO FACES PERRETT, D . I . , SMITH, P.A. Psychological Laboratory, U n i v e r s i t y of St. Andrews, Fife KY16 9JU, Scotland Substantial numbers of c e l l s have been found in the macaque temporal cortex to respond to the sight of faces but not to other simple, complex or arousing s t i m u l i I , 2. We have investigated the s e n s i t i v i t y of 96 such c e l l s to d i f f e r e n t faces in the superior temporal sulcus of 3 macaque monkeys. Picture faces. T h i r t y - e i g h t c e l l s while responding well to s t a t i c 3-dimensional (3-D) faces were r e l a t i v e l y or t o t a l l y unresponsive to l i f e
sized 2-
dimensional (2-D) photographs, projected slides and videao images of real faces. Increased response to 3-D faces was found even under monocular viewing and therefore could be independent of stereo depth. By contrast 5 c e l l s responded only to p a r t i c u l a r p i c t u r e faces and I only to pictures of monkey faces. Cells responsive to 2-D faces resoonded e q u i v a l e n t l y to colour or monochrome images but 7/11 were less responsive to photographic negatives. I d e n t i t y . Many c e l l s were s e l e c t i v e amongst 3-D faces, responding to real human faces but not to 3-D model faces (24 c e l l s ) or monkey faces (3 c e l l s ) . Thirteen c e l l s were found to be h i g h l y selective f o r p a r t i c u l a r i n d i v i d u a l s f a m i l i a r to the monkey. Differences in response to d i f f e r e n t i n d i v i d u a l s were consistent across a great v a r i e t y of viewing conditions changing face expression, o r i e n t a t i o n , colour, distance and size. Differences in c e l l response were found to arise from independent s e n s i t i v i t y to several features of the preferred face and t h e i r combination or c o n f i g u r a t i o n . The a c t i v i t y of such c e l l s could well provide information p e r t i n e n t to the d i s c r i m i n a t i o n of face i d e n t i t y . Rotation. Isomorphic r o t a t i o n of faces such that they were horizontal or inverted while not preventing c e l l s from responding was found to increase the latency of response by 10-90 ms f o r some c e l l s .
In behavioural tasks requiring
the d i s c r i m i n a t i o n of face form (from normal and jumbled feature arrays) and face i d e n t i t y we f i n d human and monkey reaction time s i m i l a r l y increased (10100 ms depending on task d i f f i c u l t y )
by stimulus r o t a t i o n .
REFERENCES I. Bruce, C.L. et a l . J. Neurophysiol., 46 (1981) 369-384. 2. P e r r e t t , D.I. et a l . Exp. Brain Res., 47 (1982) 329-342.
SENSITIVITY TO IDENTITY AND 3-DIMENSIONAL STRUCTUREAMONGTEbIPORAL CORTICAL CELLS SELECTIVELY RESPONSIVE TO FACES PERRETT, D . I . , SMITH, P.A. Psychological Laboratory, U n i v e r s i t y of St. Andrews, Fife KY16 9JU, Scotland Substantial numbers of c e l l s have been found in the macaque temporal cortex to respond to the sight of faces but not to other simple, complex or arousing s t i m u l i I , 2. We have investigated the s e n s i t i v i t y of 96 such c e l l s to d i f f e r e n t faces in the superior temporal sulcus of 3 macaque monkeys. Picture faces. T h i r t y - e i g h t c e l l s while responding well to s t a t i c 3-dimensional (3-D) faces were r e l a t i v e l y or t o t a l l y unresponsive to l i f e
sized 2-
dimensional (2-D) photographs, projected slides and videao images of real faces. Increased response to 3-D faces was found even under monocular viewing and therefore could be independent of stereo depth. By contrast 5 c e l l s responded only to p a r t i c u l a r p i c t u r e faces and I only to pictures of monkey faces. Cells responsive to 2-D faces resoonded e q u i v a l e n t l y to colour or monochrome images but 7/11 were less responsive to photographic negatives. I d e n t i t y . Many c e l l s were s e l e c t i v e amongst 3-D faces, responding to real human faces but not to 3-D model faces (24 c e l l s ) or monkey faces (3 c e l l s ) . Thirteen c e l l s were found to be h i g h l y selective f o r p a r t i c u l a r i n d i v i d u a l s f a m i l i a r to the monkey. Differences in response to d i f f e r e n t i n d i v i d u a l s were consistent across a great v a r i e t y of viewing conditions changing face expression, o r i e n t a t i o n , colour, distance and size. Differences in c e l l response were found to arise from independent s e n s i t i v i t y to several features of the preferred face and t h e i r combination or c o n f i g u r a t i o n . The a c t i v i t y of such c e l l s could well provide information p e r t i n e n t to the d i s c r i m i n a t i o n of face i d e n t i t y . Rotation. Isomorphic r o t a t i o n of faces such that they were horizontal or inverted while not preventing c e l l s from responding was found to increase the latency of response by 10-90 ms f o r some c e l l s .
In behavioural tasks requiring
the d i s c r i m i n a t i o n of face form (from normal and jumbled feature arrays) and face i d e n t i t y we f i n d human and monkey reaction time s i m i l a r l y increased (10100 ms depending on task d i f f i c u l t y )
by stimulus r o t a t i o n .
REFERENCES I. Bruce, C.L. et a l . J. Neurophysiol., 46 (1981) 369-384. 2. P e r r e t t , D.I. et a l . Exp. Brain Res., 47 (1982) 329-342.