Altered vision on the hands: Introducing the body boundary hypothesis

J. Eric T Taylor, Purdue University

Abstract

Perception operates differently within different regions of space. For example, stimuli within reaching distance are perceived differently than stimuli beyond reaching distance. Given that perception is sensitive to these regions, henceforth referred to as perceptual boundaries, it is incumbent upon theories of visual perception to identify and describe them. While some perceptual boundaries are well described in the literature, such as nearspace (peripersonal space) or graspable (peri-hand) space, I propose that others have yet to be described. Specifically, I theorize that stimuli in contact with the surface of the body are attended to differently than stimuli in peripersonal space, making the surface of the body a perceptual boundary. In this dissertation, I begin to describe the manner in which visual attention treats stimuli on the body. I employed a spatial cueing paradigm to assess how attention is deployed to the surface of the hands. Stimuli were projected onto or near participants' hands such that detecting invalidly cued targets sometimes required shifting attention across the surface of the hands. I observed the body boundary effect: a delayed orienting of attention between near-hand space to the hand (Experiments 1A & 1B) and from hand to hand (Experiment 2). In contrast to typical findings in object-based attention, this delayed orienting also occurred when shifting attention within the space occupied by a hand (Experiment 3). This effect was differentially sensitive to different surfaces of the body (Experiments 4A & 4B). Finally, I show that grasping a tool induced delayed orienting to the end of the tool, as though it were incorporated into the body boundary (Experiment 5). I suggest that this body boundary could assist the guidance of action by making attention predisposed to avoid orienting toward the hands and instead toward near-hand space, where the targets of actions are usually located.

Degree

Ph.D.

Advisors

Proctor, Purdue University.

Subject Area

Psychology|Cognitive psychology|Physiological psychology

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