Citation

Cohen EH, Schnitzer BS, Gersch TM, Singh MK, Kowler E. Vision Res. 2007; 47(14): 1907-1923.

Affiliation

Department of Psychology and Center for Cognitive Science, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ 08854, USA.

Copyright

(Copyright © 2007, Elsevier Publishing)

DOI

10.1016/j.visres.2007.03.018

PMID

17499833

PMCID

PMC2736607

Abstract

Saccades aimed at spatially extended targets land reliably at central locations determined by pooling information across the target shape [Melcher, D.,&Kowler, E. (1999). Shape, surfaces and saccades. Vision Research, 39, 2929-2946; Vishwanath, D., and Kowler, E. (2003). Localization of shapes: Eye movements and perception compared. Vision Research, 43, 1637-1653]. Previous findings of saccadic errors when attempting to look at a target in the midst of distractors encouraged suggestions that pooling occurs indiscriminately, with little or no influence of a selective filter to eliminate the influence of nearby distractors. To determine the effectiveness of filtering, saccadic localization was studied for saccades made to a set of target elements (discs) interleaved with an equivalent set of distractors of a different color. With such interleaved elements, selection and spatial pooling are constrained to occur over the same spatial region. The results showed that filtering was effective and saccadic landing position was determined mainly by the target elements. Concurrent perceptual judgments made about the same stimuli (estimating the mean size of either target or distractor discs) showed better performance for the target discs than distractors, confirming that perceptual attention was allocated to the set of target elements. These results: (1) support the role of attention in setting the input to the spatial pooling process that guides saccades to spatially extended targets, and (2) show that perceptual judgments of mean value, often thought to impose modest attentional demands, are not immune to the constraints of this pre-saccadic filter.

Language: en