Tri-stable stimuli reveal interactions among subsequent percepts: rivalry is biased by perceptual history.

In rivalry, constant stimuli allow several interpretations ("percepts"). Percepts are characterized by their probability to occur and by the duration of their dominance. During continuous presentation of bi-stable stimuli, both percept probabilities are trivially 50%. To disentangle the processes triggering a percept from those stabilizing it, we introduce tri-stable stimuli having three percepts. We find the probability and dominance duration of a percept independently adjustable. Percept probabilities and dominance durations show mutual dependencies across several perceptual switches. Consequently, the current perceptual experience depends on perceptual history; therefore, rivalry--even for continuous presentation--is not a memory-less process.