Rhythmic Modulation of Visual Discrimination is Dependent on Individuals' Spontaneous Motor Tempo

Rhythmic structure in our daily experience originates from various sources. It is generated endogenously and observed in spontaneous fluctuations in behaviour and performance. It can also arise exogenously from everyday stimuli, such as speech, motion and music. Here we examined how individual differences in spontaneous motor rhythms affect the tendency to use external rhythmic structure to guide perception. To measure individual differences in spontaneous rhythms of performance we utilized a spontaneous tapping task. To measure individual differences in perceptual rhythmic modulation we designed a visual discrimination task in which targets can appear either in-phase or out-of-phase with a preceding rhythmic stream of visual stimuli. We manipulated the tempo of the visual stream over different experimental blocks (0.77 Hz, 1.4 Hz, 2 Hz). We found that visual rhythmic stimulation modulates discrimination performance. The modulation was dependent on the tempo of stimulation, with maximal perceptual benefits for the slowest tempo of stimulation (0.77 Hz). Most importantly, the strength of modulation was also affected by individuals spontaneous motor tempo. Specifically, individuals with slower spontaneous tempi showed greater rhythmic modulation compared to individuals with faster spontaneous tempi. This discovery suggests that different tempi affect the cognitive system with varying levels of efficiency, and that self-generated rhythms impact our ability to utilize rhythmic structure in the environment for guiding perception and performance.