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ERIC Number: EJ945655
Record Type: Journal
Publication Date: 2011-Oct
Pages: 16
Abstractor: As Provided
Reference Count: 49
ISSN: ISSN-0096-1523
Direct Perception of Action-Scaled Affordances: The Shrinking Gap Problem
Fajen, Brett R.; Matthis, Jonathan S.
Journal of Experimental Psychology: Human Perception and Performance, v37 n5 p1442-1457 Oct 2011
The aim of this study was to investigate the perception of possibilities for action (i.e., affordances) that depend on one's movement capabilities, and more specifically, the passability of a shrinking gap between converging obstacles. We introduce a new optical invariant that specifies in intrinsic units the minimum locomotor speed needed to safely pass through a shrinking gap. Detecting this information during self-motion requires recovering the component of the obstacles' local optical expansion attributable to obstacle motion, independent of self-motion. In principle, recovering the obstacle motion component could involve either visual or non-visual self-motion information. We investigated the visual and non-visual contributions in two experiments in which subjects walked through a virtual environment and made judgments about whether it was possible to pass through a shrinking gap. On a small percentage of trials, visual and non-visual self-motion information were independently manipulated by varying the speed with which subjects moved through the virtual environment. Comparisons of judgments on such catch trials with judgments on normal trials revealed both visual and non-visual contributions to the detection of information about minimum walking speed. (Contains 13 figures and 4 footnotes.)
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A