Purpose. Can orientation and direction selective adaptation occur without direct visual awareness of the adapting stimulus? Methods. Crowding was employed to "hide" the adapting stimulus from subjects' direct perceptual awareness. Contrast threshold of a test grating was measured after adapting to a single grating or an "inaccessible" central grating in a crowded array (see Figure below). The adapt and test gratings could be in the same or orthogonal orientation for the orientation case and same or opposite direction for the motion case. Results. Although observers could not report the orientation of the central adapting grating, it nevertheless produced an undiminished orientation-specific adaptation effect. But motion tests showed less direction-specific threshold elevation when the adapting pattern was crowded compared to when the adapting pattern was presented alone. Conclusions. 1. Orientation specific adaptation can happen without perceptual awareness of the adapting orientation. 2. The site where crowding starts to limit our perception must be beyond V1. 3. Motion adaptation is reduced by "crowding", possibly because it involves more (and higher level) structures compared to orientation adaptation. (Figure Presented).
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|