Descartes's blind man revisited: bimanual triangulation of distance using static hand-held rods.

Full Abstract

Analogous to binocular convergence, we tested Descartes's proposal that a blind person could triangulate distances using crossed hand-held rods by sensing hand separation and wrist angles. In Experiment 1, 22 participants judged distances to loci at 4 distances, 18-36 in. (45.7-91.4 cm), at 5 eccentricities, 0-12 in. (0-30.5 cm) left and right of center. Participants reliably differentiated and scaled distances. The median individual multiple correlation (actual distances and eccentricities vs. judged distances; nonlinear with eccentricity) was .91 (range, .75 to .95; group R = .98). In Experiment 2, 2 experienced observers judged 7 distances, 30-66 in. (76.2-167.6 cm) at 7 eccentricities, 0-18 in. (0-45.7 cm) left and right. Results replicated those of Experiment 1, with nonlinear multiple Rs of .97 and .99 for the 2 participants. Bimanual triangulation supported reliable distance judgments, comparable to binocular distance perception. No evidence of perceptual learning was found.

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Author information

Author/s: Cabe, Patrick A (PA); Wright, Cheryl D (CD); Wright, Mark A (MA);

Affiliation: Department of Psychology, University of North Carolina at Pembroke, P.O. Box 1510, Pembroke, NC 28372-1510, USA. patrick.cabe(-atsign-)uncp.edu

Journal and publication information

Publication Type: Clinical Trial; Journal Article; Randomized Controlled Trial

Journal: The American journal of psychology (Am J Psychol), published in United States. (Language: eng)

Reference: 2003-; vol 116 (issue 1) : pp 71-98

Dates: Created 2003/04/24; Completed 2003/07/21; Revised 2004/11/17;

PMID: 12710223, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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