Interactions between global motion and local binocular rivalry.

Binocular rivalry is thought to arise from a low-level cortical site. Experiment 1 evaluates this claim with respect to local and global motion processing by using a multiple-aperture motion stimulus and measuring the predominance of global coherence while one of the component gratings is engaged in rivalry. Results show that rivalry suppression of the component grating precludes global coherence. Presumable, suppression prevents the component motion signal from advancing to higher-level global motion areas, suggesting rivalry occurs between local and global motion processing. However, feedback from higher-level mechanisms might exert an influence on binocular rivalry and thus Experiment 2 measures how the predominance of a local target engaged in binocular rivalry with a competing local stimulus is affected when the target forms part of a globally coherent motion stimulus. The augmented level of target predominance during global motion relative to local motion indicates that higher-level motion mechanisms can feedback and influence the binocular rivalry process. Together, these data imply a looping hierarchy of motion processing stages, with rivalry suppression transpiring at an intermediate level and subject to feedback from higher-level motion areas.