Similar but separate systems underlie perceptual bistability in vision and audition

Abstract

The dynamics of perceptual bistability, the phenomenon in which perception switches between different interpretations of an unchanging stimulus, are characterised by very similar properties across a wide range of qualitatively different paradigms. This suggests that perceptual switching may be triggered by some common source. However, it is also possible that perceptual switching may arise from a distributed system, whose components vary according to the specifics of the perceptual experiences involved. Here we used a visual and an auditory task to determine whether individuals show cross-modal commonalities in perceptual switching. We found that individual perceptual switching rates were significantly correlated across modalities. We then asked whether perceptual switching arises from some central (modality-) task-independent process or from a more distributed task-specific system. We found that a log-normal distribution best explained the distribution of perceptual phases in both modalities, suggestive of a combined set of independent processes causing perceptual switching. Modality- and/or task-dependent differences in these distributions, and lack of correlation with the modality-independent central factors tested (ego-resiliency, creativity, and executive function), also point towards perceptual switching arising from a distributed system of similar but independent processes.

Figure 1

Mean number of perceptual switches during a 180-second block in each condition and modality. Error bars indicate 95% confidence intervals.

Figure 2

Correlations in the number of perceptual switches across modalities, separately for each condition; shading indicates 95% confidence intervals of the slope of the regression line.

Figure 3

QQ-plots of gamma (left) and log-normal (right) distributions for phase durations from the Neutral conditions in the auditory (upper row) and visual (lower row) modalities.

Figure 4

Mu and Sigma parameters of the log-normal distribution with 95% confidence intervals.

Figure 5

Mnemonics for the perceptual interpretations of the ambiguous structure-from-motion stimulus; LEFT, RIGHT and the key assignment.

Figure 6

Mnemonics for the perceptual interpretations of the tone sequence; INTEGRATED, SEGREGATED, and the key assignment.