A test of Levelt's second proposition for binocular rivalry.

Levelt's second proposition (1968) was tested by investigating the effect of increasing the stimulus strength on the ipsilateral mean dominance duration. In three experiments, three stimulus dimensions were investigated: luminance contrast, colour contrast, and motion velocity. We included an experiment similar to Levelt's own equipment, in which a reversed contrast stimulus was used. In all three experiments, including the Levelt disk-ring experiment, the proposition was rejected. We conclude that Levelt's proposition cannot always be generalized to a broad class of stimulus dimensions and therefore cannot be held against reciprocal inhibition models.