ATTENTIONAL CONTROL OF SPATIAL SCALE - EFFECTS ON SELF-ORGANIZED MOTION PATTERNS

Prior to the presentation of a test stimulus, subjects' attentional st ate was either narrowly focused on a particular location or broadly sp read over a large spatial region. In previous studies, it was found th at broadly spread attention enhances the sensitivity of relatively lar ge spatial filters (increasing the perceiver's spatial scale), thereby diminishing spatial resolution and enhancing sensitivity to global st imulus structure. In this study it is shown that attentional spread al so affects the self-organization of unidirectional versus oscillatory motion patterns for the directionally ambiguous, counterphase presenta tion of rows of evenly-spaced visual elements (lines segments; dots); i.e. qualitatively different motion patterns can be formed for the sam e stimulus at different spatial scales. Although the degree to which a ttention is spread along a spatial axis can be controlled by the perce iver, the effects of spread attention are not limited to a single axis . These results, as well as previously observed effects of attentional spread on spatial resolution, are accounted for by a neural model inv olving large, foveally-centered receptive fields with co-operatively i nteracting subunits (probably at the level of MST or higher). (C) 1998 Elsevier Science Ltd. All rights reserved.