Slow and fast visual motion channels have independent binocular-rivalry stages

We have previously reported a transparent motion after-effect indicating th at the human visual system comprises separate slow and fast motion channels . Here, we report that the presentation of a fast motion in one eye and a s low motion in the other eye does not result in binocular rivalry but in a c lear percept of transparent motion. We call this new visual phenomenon 'dic hoptic motion transparency' (DMT). So far only thr DMT phenomenon and the t wo motion after-effects (the 'classical' motion after-effect, seen after mo tion adaptation on a static test pattern, and the dynamic motion after-effe ct, seen on a dynamic-noise test pattern) appear re, isolate the channels c ompletely The speed ranges of the slow and fast channels overlap strongly a nd are observer dependent. A model is presented that links after-effect dur ations of an observer Co the probability of rivalry or DMT as a function of dichoptic velocity combinations. Model results support the assumption of t wo highly independent channels showing only within-channel rivalry, and no rivalry or after-effect interactions between the channels. The finding of t wo independent motion vision channels, each with a separate rivalry stage a nd a private line to conscious perception, might be helpful in visualizing or analysing pathways to consciousness.