Abstract
Previous work on spatial contextual interactions between shapes defined by radial frequency (RF) contours has demonstrated that such interactions depend on the rotational phase alignment between a mask and target stimulus (Habak et al., 2004; 2009). When the points of maximum curvature in target and masking RF contours are aligned (i.e., zero phase difference), thresholds for detecting deviations from circularity are significantly elevated relative to a baseline condition that contains no masking stimulus, and the strength of masking declines as the relative phase difference increases (Habak et al., 2004; 2009). The current study extended this previous work by examining the effect of RF number on the magnitude of threshold elevation observed across seven target-mask relative phases. We measured detection thresholds for five RF contours (RF3, 5, 6, 8, 11) in the presence of a surrounding mask of the same RF number as the target in seven target-mask relative phase combinations (0°, 30°, 60°, 90°, 120°, 150°, 180°). Although the amount of masking varied considerably across RF contours, we found that the magnitude of masking declined with increasing relative target-mask phase difference for all RF combinations. However, we also found a significant interaction between RF number and phase such that the rate at which masking declined with phase differed across RF contours. Overall, these results suggest significant differences exist in how the frequency of local curvature affects the interference observed as a function of the alignment between two shapes. The results of this study serve as a foundation for interpreting the effect of rotational phase alignment between spatially separated shapes.
Meeting abstract presented at VSS 2015