Bistable figures provide a fascinating window through which to explore human visual awareness. Here we demonstrate for the first time that the semantic context provided by a background auditory soundtrack can modulate an observer’s predominant percept while watching the bistable “my wife or my mother-in-law” figure . The possibility of a response-bias account—that participants simply reported the percept that happened to be congruent with the soundtrack that they were listening to—was excluded in Experiment 2. We further demonstrate that this crossmodal (...) semantic effect was additive with the manipulation of participants’ visual fixation , while it interacted with participants’ voluntary attention . These results indicate that audiovisual semantic congruency constrains the visual processing that gives rise to the conscious perception of bistable visual figures. Crossmodal semantic context therefore provides an important mechanism contributing to the emergence of visual awareness. (shrink)

Illusions that produce perceptual suppression despite constant retinal input are used to manipulate visual consciousness. Here we report on a powerful variant of existing techniques, Continuous Flash Suppression. Distinct images flashed successively around 10 Hz into one eye reliably suppress an image presented to the other eye. Compared to binocular rivalry, the duration of perceptual suppression increased more than 10-fold. Using this tool we show that the strength of the negative afterimage of an adaptor was reduced by half when it (...) was perceptually suppressed by input from the other eye. The more likely the adaptor was completely suppressed, the larger the reduction of the afterimage intensity. Paradoxically, trial-to-trial visibility of the adaptor did not correlate with the degree of suppression. Our results imply that formation of afterimages involves neuronal structures that access input from both eyes, but that do not correspond directly to the neuronal correlates of perceptual awareness. (shrink)