Differential effects of visual attention and working memory on binocular rivalry

The investigation of cognitive influence on binocular rivalry has a long history. However, the effects of visual WM on rivalry have never been studied so far. We examined top-down modulation of rivalry perception in four experiments to compare the effects of visual WM and sustained selective attention: In the first three experiments we failed to observe any sustained effect of the WM content; only the color of the memory probe was found to prime the initially dominant percept. In Experiment 4 we found a clear effect of sustained attention on rivalry both in terms of the first dominant percept and of the overall dominance when participants were involved in a tracking task. Our results provide an example of dissociation between visual WM and selective attention, two phenomena which otherwise functionally overlap to a large extent. Furthermore, our study highlights the importance of the task employed to engage cognitive resources: The observed perceptual epiphenomena of binocular rivalry are indicative of visual competition at an early stage, which is not affected by WM but is still susceptible to attention influence as long as the observer's attention is constrained to one of the two rival images via a specific concomitant task.