FROM EGOCENTRIC TO ALLOCENTRIC SPATIAL-BEHAVIOR - A COMPUTATIONAL MODEL OF SPATIAL DEVELOPMENT

Psychological experiments on children's development of spatial knowled ge suggest that experience at self-locomotion and visual tracking are important factors. Yet, the mechanism underlying development is unknow n. We propose a robot that learns to track a target object mentally (i .e., maintaining a representation of an object's position when outside the field of view) as a model for spatial development Mental tracking is considered as prediction of an object's position, given the previo us environmental state and motor commands and the current environment state resulting from movement Following Jordan and Rumelhart's (1992) forward modeling architecture, the system consists of two components: an inverse model of sensory input to desired meter commands and a forw ard model of motor commands to desired sensory input (goals). The robo t was tested on the ''three cups'' paradigm lin which children are req uired, under Various movement conditions, to select the cup containing the hidden object). Consistent with child development, in the absence of the capacity for self-locomotion, the robot makes errors that are self-center-based. When given the ability for self-locomotion, the rob ot responds allocentrically.