Exploratory movement generates higher-order information that is sufficient for accurate perception of scaled egocentric distance.

Bruno Mantel,Alain Campbell,Thomas A Stoffregen,Benoît G Bardy,Suliann Ben Hamed

doi:10.1371/journal.pone.0120025

Abstract

Body movement influences the structure of multiple forms of ambient energy, including optics and gravito-inertial force. Some researchers have argued that egocentric distance is derived from inferential integration of visual and non-visual stimulation. We suggest that accurate information about egocentric distance exists in perceptual stimulation as higher-order patterns that extend across optics and inertia. We formalize a pattern that specifies the egocentric distance of a stationary object across higher-order relations between optics and inertia. This higher-order parameter is created by self-generated movement of the perceiver in inertial space relative to the illuminated environment. For this reason, we placed minimal restrictions on the exploratory movements of our participants. We asked whether humans can detect and use the information available in this higher-order pattern. Participants judged whether a virtual object was within reach. We manipulated relations between body movement and the ambient structure of optics and inertia. Judgments were precise and accurate when the higher-order optical-inertial parameter was available. When only optic flow was available, judgments were poor. Our results reveal that participants perceived egocentric distance from the higher-order, optical-inertial consequences of their own exploratory activity. Analysis of participants’ movement trajectories revealed that self-selected movements were complex, and tended to optimize availability of the optical-inertial pattern that specifies egocentric distance. We argue that accurate information about egocentric distance exists in higher-order patterns of ambient energy, that self-generated movement can generate these higher-order patterns, and that these patterns can be detected and used to support perception of egocentric distance that is precise and accurate.

Highlights

Animate movement alters the structure of multiple forms of ambient energy
Information about egocentric distance requires that optic flow be scaled
Optic flow might have been scaled as a fact of ambient energy through a higher order pattern comprising haptic/gravito-inertial stimulation, as we suggest

Summary

Introduction

Animate movement alters the structure of multiple forms of ambient energy. Consider walking. In theories of indirect perception it is assumed that patterns of stimulation available to the perceiver bear an ambiguous relation to physical reality If this is true, accurate perception can occur only as a product of inferential processing within the nervous system. In theories of direct perception it is argued that patterns of stimulation available to the perceiver bear a unique, lawful relation to physical reality [6,7,8,9,10] If this is true, and if perceivers are sensitive to the relevant patterns of stimulation, sensory stimulation may be sufficient for accurate perception, such that inferential processing is not required. We argue that the epistemological assumptions of direct perception can apply to the multisensory consequences of animate movement [6]

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Discussion

Conclusion