[Characteristics of contralateral suppression along the vertical meridian]

A hypothesis has been advanced which suggests that the magnitude of suppression in binocular rivalry along the horizontal meridian is stronger at the center of the rivalrous pattern than at its peripheral. It was tested whether this hypothesis can be extended to the vertical meridian. Accuracy in detecting a briefly flashed target superimposed upon the completely suppressed pattern during binocular rivalry was measured at each of two target positions combined with two fixation positions along the vertical meridian (Exp. I). As a control experiment, target-detection performance in monocular observation was examined (Exp. II). The results obtained from one of the two subjects supported this hypothesis, although the effect of position within the rivalrous pattern was less marked than that obtained along the horizontal meridian. The results obtained from the other subject suggested that there was little difference in suppression effect between the center and the upper end of the pattern. These results suggest that the variation in suppression effect within the pattern along the vertical meridian is smaller than that along the horizontal meridian.