Orientation-selective adaptation during motion-induced blindness.

When a global moving pattern is superimposed on high-contrast stationary or slowly moving stimuli, the latter occasionally disappear for periods of several seconds (motion-induced blindness, MIB). Here, an adaptation paradigm was used to determine if orientation-selective adaptation still occurs for the stimulus that is no longer visible. Two slowly drifting high-contrast Gabor patches were presented to observers. As soon as both patches disappeared, one was eliminated from the screen. After 2 s, two low-contrast Gabor patches were presented as tests at the same locations and observers were asked to report their orientations. The observers' performance was significantly higher when the orientation of the low-contrast test patch was orthogonal to the orientation of the high-contrast adapting patch (p < 0.0001) for the location where the patch was present during MIB, even though it was perceptually invisible. The observers' performance was not significantly different at the adjacent control location where the stimulus was absent during the MIB. Although no stimulus was visible at either location, orientation-selective adaptation was preserved only for the location at which the patch remained present. Since orientation information is processed in low-level visual areas such as the primary visual cortex (V1), we conclude that MIB originates in an area higher than V1.