PERCEPTION WITH LITTLE AWARENESS: THE WINNING GROUP TAKES ALL.
                                                   Y. Bonneh1, A. Cooperman2, D. Sagi2.
Scientitic Learning Corp, Berkeley, CA1; Weizmann Institute of Science, Rehovot, ISRAEL2.

Purpose: We have recently reported a new phenomena of Motion Induced Blindness (MIB) (Bonneh et al., ARVO99) where high-contrast patterns disappear from visual awareness for several seconds when presented together with an overlapping or near moving pattern. Here we use the phenomenon to study perceptual organization under conditions of low awareness. Methods: Observers viewed two high contrast Gabor patches (targets) in the upper-left quadrant (2 deg from fixation), together with a black random dot pattern (mask) arranged on the surface of a 7 deg (diameter) rotating sphere on a gray background. Observers were instructed to attend to the rotating mask and simultaneously depress buttons to report disappearance of the two targets independently. Local orientation and position of the two patches were manipulated between collinear and orthogonal as well as in a full overlap. Results: Individual target Gabor patches were reported to disappear (4 observers) for 20% - 60% (individual differences) of presentation time. The correlation between the two targets disappearances depended on configuration: positive (0.3-0.9) for the collinear configuration (single object) and low positive or negative (-0.5 to 0.2) for orthogonal patches (object rivalry). When the orthogonal patches overlapped (plaid), a strong monocular-rivalry could be observed (as compared with none without the moving structure). When small line grating (orthogonal) patches were presented dichoptically to induce binocular rivalry, the speed of rivalry alternations slowed down (factor 2) with the moving mask (presented to both eyes), as compared to a static presentation. Conclusions: Motion induced blindness (MIB) can expose functional properties of low level visual mechanisms such as object binding by long-range interactions and object competition. In conditions of low awareness, (1) long range interactions operate to define perceptual objects and (2) enhanced competition takes place with one object gaining long term access to consciousness (extinction). 


Yoram Bonneh

Last modified: Fri Dec 3 11:42:08 PST 1999