Hierarchical Structure of Musical and Visual Meter in Cross-modal "Fit" Judgments

The metrical hierarchy of musical rhythm is defined by the structure of emphasis on beats in measures and has been studied in several ways [1]. Here we investigated the perceived structure of 3/4 and 4/4 time signatures in auditory and visual meter using cross-modal goodness-of-fit ratings for visual and auditory probes, respectively. In the auditory context conditions, four measures in 3/4 or 4/4 time were defined by a louder beat followed a series of 2 or 3 softer, equally-timed beats, respectively. A visual probe circle was introduced into the next four measures at one of 12 phaseangles relative to the auditory downbeat: 0, 45, 60, 90, 120, 135, 180, 225, 240, 270, 300, or 315 degrees. In the visual context conditions, context and probe modalities were reversed, with analogous visual rhythms being defined by a larger downbeat circle followed by a series of 2 or 3 smaller circles, with an auditory probe in the last four measures at one of the same 12 phase-angles. Participants rated how well the probe stimulus "fit" the rhythmic context in the other modality. For the visual context conditions, the probe’s effect on fit-ratings revealed the expected beat-defined metrical hierarchy. In 4/4 time, fit ratings were highest for beat 1, next highest for probes at (or near) beats 2, 3, and 4, and lowest for probes at non-beats. In 3/4 time, they decreased similarly from beat 1 to beats 2 and 3, and from them to non-beats. The auditory context conditions produced unexpected results, however, with a single broad peak at and following the downbeat, and little evidence of elevated fit ratings for other beats over non-beats. Similar results were obtained when participants made explicit ratings of cross-modal synchrony using the same stimuli. Various factors relevant to explaining the asymmetry between these cross-modal conditions are discussed.