Hemispheric differences in the interference among components of compound gratings.
The relationship between local/global and high/low spatial-frequency processing in hemispheric asymmetries was explored. Subjects were required to judge the orientation of a high- or low-spatial-frequency component of a compound grating presented in the left visual field (LVF) or right visual field (RVF). In Experiment 1, attention was focused on one or the other component. A signal detection analysis indicated that sensitivity (d') to the high-spatial-frequency target was reduced more by the presence of the low-spatial-frequency component when both were presented in the LVF rather than in the RVF. In Experiment 2, subjects determined whether a target orientation was present, independent of spatial frequency at only a single level (i.e., at the high- or low-spatial-frequency level), as opposed to both or neither level. An RVF/LH (left hemisphere) advantage was found when the decision was based on the orientation of the high-frequency component. The asymmetrical influence of visual field of presentation and spatial frequency upon sensitivity is discussed in terms of hemispheric differences in the magnitude of inhibition between spatial-frequency channels and in the role of transient channel activity to capture and direct higher order attentional processes.
Kitterle
F L
FL
Department of Psychology, Stephen F. Austin State University, Nacogdoches, TX 75962.
Christman
S
S
Conesa
J
J
D001921:Brain / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time; D013028:Space Perception; D014794:Visual Fields; D014796:Visual Perception