SPATIAL INTERACTIONS IN IDENTIFICATION AND DETECTION OF COMPOUND VISUAL STIMULI

Identification and detection thresholds were obtained for stimuli varying in width from 10 min to 40 min of visual angle. Stimuli were presented singly or in pairs, a smaller and a larger one superimposed. In the pairs, the larger component was usually more easily identified and appeared to mediate detection. Both identification of the larger component and detection of the compound were facilitated by increasing the relative width of the smaller component. When the stimuli were presented singly, width had no reliable effect. The results suggest that stimulation is simultaneously processed by several receptive field mechanisms which are coaxial but have different spatial dimensions. The configuration of the stimulus determines which mechanism is dominant. © 1969.