DEICTIC CODES FOR THE EMBODIMENT OF COGNITION

To describe phenomena that occur at different time scales, computation al models of the brain must incorporate different levels of abstractio n. At time scales of approximately 1/3 of a second, orienting movement s of the body play a crucial role in cognition and form a useful compu tational level - more abstract than that used to capture natural pheno mena but less abstract than what is traditionally used to study high-l evel cognitive processes such as reasoning. At this ''embodiment level ,'' the constraints of the physical system determine the nature of cog nitive operations. The key synergy is that at time scales of about 1/3 of a second, the natural sequentiality of body movements can be match ed to the natural computational economies of sequential decision syste ms through a system of implicit reference called deictic in which poin ting movements are used to bind objects in the world to cognitive prog rams. This target article focuses on how deictic bindings make it poss ible to perform natural tasks. Deictic computation provides a mechanis m for representing the essential features that link external sensory d ata with internal cognitive programs and motor actions. One of the cen tral features of cognition, working memory, can be related to moment-b y-moment dispositions of body features such as eye movements and hand movements.