EVIDENCE ACCUMULATION IN CELL-POPULATIONS RESPONSIVE TO FACES - AN ACCOUNT OF GENERALIZATION OF RECOGNITION WITHOUT MENTAL TRANSFORMATIONS

In this paper we analyse the time course of neuronal activity in tempo ral cortex to the sight of the head and body. Previous studies have al ready demonstrated the impact of view, orientation and part occlusion on individual cells. We consider the cells as a population providing e vidence in the form of neuronal activity for perceptual decisions rela ted to recognition. The time course of neural responses to stimuli pro vides an explanation of the variation in speed of recognition across d ifferent viewing circumstances that is seen in behavioural experiments . A simple unifying explanation of the behavioural effects is that the speed of recognition of an object depends on the rate of accumulation of activity from neurones selective for the object, evoked by a parti cular viewing circumstance. This in turn depends on the extent that th e object has been seen previously under the particular circumstance. F or any familiar object, more cells will be tuned to the configuration of the object's features present in the view or views most frequently experienced. Therefore. activity amongst the population of cells selec tive for the object's appearance will accumulate more slowly when the object is seen in an unusual view, orientation or size. This accounts for the increased time to recognise rotated views without the need to postulate 'mental rotation' or 'transformations' of novel views to ali gn with neural representations of familiar views. (C) 1998 Elsevier Sc ience B.V. All rights reserved.