Abstract:
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Recent research has demonstrated top–down effects on meter induction in the auditory
modality. However, little is known about these effects in the visual domain, especially
without the involvement of motor acts such as tapping. In the present study, we
aim to assess whether the projection of meter on auditory beats is also present in
the visual domain. We asked 16 musicians to internally project binary (i.e., a strongweak
pattern) and ternary (i.e., a strong-weak-weak pattern) meter onto separate,
but analog, visual and auditory isochronous stimuli. Participants were presented with
sequences of tones or blinking circular shapes (i.e., flashes) at 2.4 Hz while their
electrophysiological responses were recorded. A frequency analysis of the elicited
steady-state evoked potentials allowed us to compare the frequencies of the beat
(2.4 Hz), its first harmonic (4.8 Hz), the binary subharmonic (1.2 Hz), and the ternary
subharmonic (0.8 Hz) within and across modalities. Taking the amplitude spectra into
account, we observed an enhancement of the amplitude at 0.8 Hz in the ternary
condition for both modalities, suggesting meter induction across modalities. There was
an interaction between modality and voltage at 2.4 and 4.8 Hz. Looking at the power
spectra, we also observed significant differences from zero in the auditory, but not in
the visual, binary condition at 1.2 Hz. These findings suggest that meter processing
is modulated by top–down mechanisms that interact with our perception of rhythmic
events and that such modulation can also be found in the visual domain. The reported
cross-modal effects of meter may shed light on the origins of our timing mechanisms,
partially developed in primates and allowing humans to synchronize across modalities
accurately. |