Moving objects are accurately perceived in an allocentric environment during locomotion

Abstract

An allocentric frame of reference is necessary to control flexible interaction with the world, but the optical stimulus is received in an egocentric frame of reference. This means that if an animal moves in the presence of a moving object, then the optical motion of the object is the combination of object motion and self-motion. How does the nervous system recover object motion in an allocentric frame of reference? The flow parsing hypothesis suggests that the visual contributions of self-motion can be deducted from the local optical motion of an object on the basis of the global motion stimulus alone. Previous studies have tested the flow parsing hypothesis in virtual environments during simulated locomotion, but demonstrate systematic distortions of object-motion perception in the allocentric frame of reference. We tested the conditions under which object-motion perception during self-motion is accurate, with respect to object-motion perception while stationary. Participants judged the trajectories of moving objects during simulated locomotion, during real locomotion, and while stationary in Experiment 1 and in textured and untextured environments in Experiment 2. We observed that object-motion perception was accurate and more precise only if observers were actively walking through a textured environment. The inaccuracies of object-motion perception during simulated locomotion and in the untextured environment have implications for the role of non-visual information about self-motion during object-motion perception.