Commonality and variation in mental representations of music revealed by a cross-cultural comparison of rhythm priors in 15 countries.

Music is present in every known society but varies from place to place. What, if anything, is universal to music cognition? We measured a signature of mental representations of rhythm in 39 participant groups in 15 countries, spanning urban societies and Indigenous populations. Listeners reproduced random 'seed' rhythms; their reproductions were fed back as the stimulus (as in the game of 'telephone'), such that their biases (the prior) could be estimated from the distribution of reproductions. Every tested group showed a sparse prior with peaks at integer-ratio rhythms. However, the importance of different integer ratios varied across groups, often reflecting local musical practices. Our results suggest a common feature of music cognition: discrete rhythm 'categories' at small-integer ratios. These discrete representations plausibly stabilize musical systems in the face of cultural transmission but interact with culture-specific traditions to yield the diversity that is evident when mental representations are probed across many cultures.

Aesthetics of musical timing: Culture and expertise affect preferences for isochrony but not synchrony.

Expressive communication in the arts often involves deviations from stylistic norms, which can increase the aesthetic evaluation of an artwork or performance. The detection and appreciation of such expressive deviations may be amplified by cultural familiarity and expertise of the observer. One form of expressive communication in music is playing "out of time," including asynchrony (deviations from synchrony between different instruments) and non-isochrony (deviations from equal spacing between subsequent note onsets or metric units). As previous research has provided somewhat conflicting perspectives on the degree to which deviations from synchrony and isochrony are aesthetically relevant, we aimed to shed new light on this topic by accounting for the effects of listeners' cultural familiarity and expertise. We manipulated (a)synchrony and (non-)isochrony separately in excerpts from three groove-based musical styles (jazz, candombe, and jembe), using timings from real performances. We recruited musician and non-musician participants (N = 176) from three countries (UK, Uruguay, and Mali), selected to vary in their prior experience of hearing and performing these three styles. Participants completed both an aesthetic preference rating task and a perceptual discrimination task for the stimuli. Our results indicate an overall preference toward synchrony in these styles, but culturally contingent, expertise-dependent preferences for deviations from isochrony. This suggests that temporal processing relies on mechanisms that vary in their dependence on low-level and high-level perception, and emphasizes the role of cultural familiarity and expertise in shaping aesthetic preferences.