Hemispheric processing of global form, local form, and texture.

Hemispheric processing of global form, local form, and texture of hierarchical patterns composed of many, relatively small elements and patterns composed of few, relatively large elements was examined in two experiments, employing a Stroop-type paradigm. In experiment 1 subjects were instructed to attend either to the global or the local level of the pattern and to identify the form at the designated level. In experiment 2 subjects were to identify the global form or the texture. A right visual field (left hemisphere) advantage was obtained for detection of local form, and a left visual field (right hemisphere) advantage was obtained for detection of global form. When many-element patterns were processed in terms of global form and texture, the results failed to show reliable hemispheric differences. The results suggest that the hemispheres differ in their sensitivity to the relatively more global versus the relatively more local aspects of visual patterns which require focused attention (as in global/local form detection). When the task involved distributed attention (as in texture detection) no lateralized effects were observed.