Are multiple fixations necessarily deictic?

Sally Bogacz
1997 Behavioral and Brain Sciences  
To describe phenomena that occur at different time scales, computational models of the brain must incorporate different levels of abstraction. At time scales of approximately 1 ⁄3 of a second, orienting movements of the body play a crucial role in cognition and form a useful computational level -more abstract than that used to capture natural phenomena but less abstract than what is traditionally used to study high-level cognitive processes such as reasoning. At this "embodiment level," the
more » ... traints of the physical system determine the nature of cognitive operations. The key synergy is that at time scales of about 1 ⁄3 of a second, the natural sequentiality of body movements can be matched to the natural computational economies of sequential decision systems through a system of implicit reference called deictic in which pointing movements are used to bind objects in the world to cognitive programs. This target article focuses on how deictic bindings make it possible to perform natural tasks. Deictic computation provides a mechanism for representing the essential features that link external sensory data with internal cognitive programs and motor actions. One of the central features of cognition, working memory, can be related to moment-by-moment dispositions of body features such as eye movements and hand movements. Abstract: Deictic coding offers a useful model for understanding the interactions between the dorsal and ventral streams of visual processing in the cerebral cortex. By extending Ballard et al.'s ideas on teleassistance, I show how dedicated low-level visuomotor processes in the dorsal stream Abstract: Ballard et al. model eye position as a deictic pointer for spatial perception. Evidence from research on gaze control indicates, however, that shifts in actual eye position are neither necessary nor sufficient to produce shifts in spatial perception. Deictic context is instead provided by the interaction between two deictic pointers; one representing actual eye position, and the other, intended eye position. Ballard et al. present evidence indicating that the spatial context for perception is provided by deictic pointers such as eye position. ACKNOWLEDGMENT Thanks are due to Bruce Bridgeman, Marc Pomplun, Andreas Sprenger, and Pieter Unema for discussion of these issues. Abstract: This commentary raises three questions about the target article: What are pointers or deictic devices? Why insist on deictic codes for cognition rather than deixis simpliciter? And in what sense is cognition embodied, on this view?
doi:10.1017/s0140525x97221618 fatcat:7zoh5xcc5bbvvbuvjwls74l6ay