Fig 2. Experimental paradigm.

Stimuli were presented discontinuously for 1000 ms with an inter-stimulus interval of 400 ms. Participants compared the current stimulus with the immediately preceding one. In case of identical percepts across two consecutive stimuli, participants pressed 'S' (stability) on a keyboard (represented as squares with the letters 'R' and 'S' below the time axis). If perception changed from one stimulus to the next, participants pressed 'R' (reversal). Stimulus type and ambiguity/visibility level stayed unchanged within experimental conditions (within rows), but differed between experimental conditions (different rows). The order of conditions (rows) was pseudo-randomized. The specific sequences of stimuli (Si1, Si2, Si3) in b—f are for demonstration purposes.