As shown above, perceptual coupling increased the proportion of simultaneous switches but, at the same time, destabilized the individual objects. Given this negative dependence between the perceptual coupling and perceptual stability, we wondered whether the same is true for the individual dominance phases. Specifically, we compared durations of the dominance phases that were preceded by a simultaneous switch in both objects and when objects switched independently. In the former case, the two objects retained the original perceptual coupling, whereas in the latter one this original coupling breaks down. To test this hypothesis, we computed an average dominance phase duration for individual
fully ambiguous objects either following an independent perceptual reversal (
Dindependent) or following a simultaneous switch in both objects (
Dsimultaneous). The duration of the dominance phase was normalized by computing a
z score for all dominance durations of the corresponding perceptual state within a block. Please note that the first and the last dominance phases were excluded from the analysis because the former is not a perceptual switch but a perceptual choice (Noest, van Ee, Nijs, & van Wezel,
2007) and the latter dominance phase is curtailed by the end of the block. As can be seen in
Figure 3C, the duration of the dominance phase was independent of the type of the preceding perceptual switch. Moreover, simultaneous switches did not lead to longer dominance phases even for the blocks with strong perceptual coupling:
t(91.88) = 0.04,
p = 0.9696,
R2 = 0.004, linear mixed-model analysis with the ratio of the
Dsimultaneous to
Dindependent as a dependent variable, balance (
Display Formula\(|{P_{counter - rotation}} - 50|/50\)) as an independent variable, and the observer identity as a random factor. Thus, the simultaneity of perceptual switches does not lead to either perceptual stability or destabilization.