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Egocentric and allocentric localization during induced motion.
Exp Brain Res. 2008 Dec; 191(4):495-504.EB

Abstract

This research examined motor measures of the apparent egocentric location and perceptual measures of the apparent allocentric location of a target that was being seen to undergo induced motion (IM). In Experiments 1 and 3, subjects fixated a stationary dot (IM target) while a rectangular surround stimulus (inducing stimulus) oscillated horizontally. The inducing stimulus motion caused the IM target to appear to move in the opposite direction. In Experiment 1, two dots (flashed targets) were flashed above and below the IM target when the surround had reached its leftmost or rightmost displacement from the subject's midline. Subjects pointed open-loop at either the apparent egocentric location of the IM target or at the bottom of the two flashed targets. On separate trials, subjects made judgments of the Vernier alignment of the IM target with the flashed targets at the endpoints of the surround's oscillation. The pointing responses were displaced in the direction of the previously seen IM for the IM target and to a lesser degree for the bottom flashed target. However, the allocentric Vernier judgments demonstrated no perceptual displacement of the IM target relative to the flashed targets. Thus, IM results in a dissociation of egocentric location measures from allocentric location measures. In Experiment 2, pointing and Vernier measures were obtained with stationary horizontally displaced surrounds and there was no dissociation of egocentric location measures from allocentric location measures. These results indicate that the Roelofs effect did not produce the pattern of results in Experiment 1. In Experiment 3, pointing and Vernier measures were obtained when the surround was at the midpoint of an oscillation. In this case, egocentric pointing responses were displaced in the direction of surround motion (opposite IM) for the IM target and to a greater degree for the bottom flashed target. However, there was no apparent displacement of the IM target relative to the flashed targets in the allocentric Vernier judgments. Therefore, in Experiment 3 egocentric location measures were again dissociated from allocentric location measures. The results of this experiment also demonstrate that IM does not generate an allocentric displacement illusion analogous to the "flash-lag" effect.

Authors+Show Affiliations

Department of Psychology, University of California, Davis, CA 95616, USA. rbpost@ucdavis.eduNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18751688

Citation

Post, Robert B., et al. "Egocentric and Allocentric Localization During Induced Motion." Experimental Brain Research, vol. 191, no. 4, 2008, pp. 495-504.
Post RB, Welch RB, Whitney D. Egocentric and allocentric localization during induced motion. Exp Brain Res. 2008;191(4):495-504.
Post, R. B., Welch, R. B., & Whitney, D. (2008). Egocentric and allocentric localization during induced motion. Experimental Brain Research, 191(4), 495-504. https://doi.org/10.1007/s00221-008-1550-2
Post RB, Welch RB, Whitney D. Egocentric and Allocentric Localization During Induced Motion. Exp Brain Res. 2008;191(4):495-504. PubMed PMID: 18751688.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Egocentric and allocentric localization during induced motion. AU - Post,Robert B, AU - Welch,Robert B, AU - Whitney,David, Y1 - 2008/08/27/ PY - 2007/11/27/received PY - 2008/08/12/accepted PY - 2008/8/30/pubmed PY - 2009/1/1/medline PY - 2008/8/30/entrez SP - 495 EP - 504 JF - Experimental brain research JO - Exp Brain Res VL - 191 IS - 4 N2 - This research examined motor measures of the apparent egocentric location and perceptual measures of the apparent allocentric location of a target that was being seen to undergo induced motion (IM). In Experiments 1 and 3, subjects fixated a stationary dot (IM target) while a rectangular surround stimulus (inducing stimulus) oscillated horizontally. The inducing stimulus motion caused the IM target to appear to move in the opposite direction. In Experiment 1, two dots (flashed targets) were flashed above and below the IM target when the surround had reached its leftmost or rightmost displacement from the subject's midline. Subjects pointed open-loop at either the apparent egocentric location of the IM target or at the bottom of the two flashed targets. On separate trials, subjects made judgments of the Vernier alignment of the IM target with the flashed targets at the endpoints of the surround's oscillation. The pointing responses were displaced in the direction of the previously seen IM for the IM target and to a lesser degree for the bottom flashed target. However, the allocentric Vernier judgments demonstrated no perceptual displacement of the IM target relative to the flashed targets. Thus, IM results in a dissociation of egocentric location measures from allocentric location measures. In Experiment 2, pointing and Vernier measures were obtained with stationary horizontally displaced surrounds and there was no dissociation of egocentric location measures from allocentric location measures. These results indicate that the Roelofs effect did not produce the pattern of results in Experiment 1. In Experiment 3, pointing and Vernier measures were obtained when the surround was at the midpoint of an oscillation. In this case, egocentric pointing responses were displaced in the direction of surround motion (opposite IM) for the IM target and to a greater degree for the bottom flashed target. However, there was no apparent displacement of the IM target relative to the flashed targets in the allocentric Vernier judgments. Therefore, in Experiment 3 egocentric location measures were again dissociated from allocentric location measures. The results of this experiment also demonstrate that IM does not generate an allocentric displacement illusion analogous to the "flash-lag" effect. SN - 1432-1106 UR - https://www.unboundmedicine.com/medline/citation/18751688/Egocentric_and_allocentric_localization_during_induced_motion_ L2 - https://dx.doi.org/10.1007/s00221-008-1550-2 DB - PRIME DP - Unbound Medicine ER -