Cross-cultural research reveals universal bias towards simple rhythmic ratios in music
A comprehensive study spearheaded by researchers from the Massachusetts Institute of Technology and the Max Planck Institute for Empirical Aesthetics provides evidence that people tend to show a predisposition towards rhythms formed by simple integer ratios regardless of cultural background. Despite these universal tendencies, the study revealed significant variations in rhythm preferences across different societies, illuminating the nuanced factors that shape musical cognition.
The findings were published in Nature Human Behaviour.
The pursuit of this research stems from a curiosity about the universality of music cognition. Across the globe, music forms an integral part of human life, yet its manifestation is as varied as the cultures that create it. Previous studies, often focused on Western societies, hinted at a mental bias towards rhythms that can be neatly divided into equal parts, like the steady beat of a heart or the ticking of a clock.
But is this a universal trait, or are our musical minds molded by the melodies and rhythms that surround us from birth? The researchers conducted this study to investigate these answers, seeking to untangle the inherent from the acquired in music cognition.
This large-scale study was carried out among 39 participant groups spanning 15 countries, encompassing both urban societies and Indigenous populations. This diverse sample allowed the researchers to explore the universality and cultural specificity of music cognition, particularly regarding rhythm.
“This is really the first study of its kind in the sense that we did the same experiment in all these different places, with people who are on the ground in those locations. That hasn’t really been done before at anything close to this scale, and it gave us an opportunity to see the degree of variation that might exist around the world,” explained senior author Josh McDermott, an associate professor of brain and cognitive sciences at MIT.
To conduct their study, the researchers utilized a method reminiscent of the game of “telephone,” where a message is whispered from one person to the next, often leading to alterations of the original message. Participants were initially presented with a random “seed” rhythm through headphones. This rhythm consisted of a repeating cycle of three clicks, separated by time intervals that, when combined, totaled two seconds. Participants were asked to reproduce this rhythm by tapping along to it, a task designed to mimic how one might naturally attempt to replicate a rhythm heard in music.
Following the initial reproduction, the participant’s version of the rhythm was then used as the new stimulus for the next iteration of reproduction. This process was iterated several times, allowing the researchers to observe how the reproduced rhythms evolved over successive iterations. The hypothesis was that the participants’ reproductions would gradually converge towards certain preferred rhythms due to their internal biases or “priors” towards specific rhythmic structures. This iterative process effectively magnified the participants’ biases, making them easier to identify and quantify.
“The initial stimulus pattern is random, but at each iteration the pattern is pushed by the listener’s biases, such that it tends to converge to a particular point in the space of possible rhythms,” McDermott explained. “That can give you a picture of what we call the prior, which is the set of internal implicit expectations for rhythms that people have in their heads.”
Across all participant groups spanning 15 countries, there was a clear inclination towards rhythms composed of simple integer ratios, such as evenly spaced beats forming a 1:1:1 ratio. This finding suggests a commonality in human music cognition — a universal bias toward perceiving and enjoying rhythms that are mathematically simple.
However, the study also highlighted the significant variation in these rhythmic preferences across different cultures. While all groups demonstrated a bias towards simple integer ratios, the specific ratios that were preferred varied greatly, reflecting the diversity of local musical practices.
Some cultures showed a particular affinity for rhythms that are prevalent in their musical traditions, indicating that while there may be a universal foundation for rhythm perception, cultural influences play a crucial role in shaping individual and collective musical preferences.
For example, the 2:2:3 rhythm was notably prominent among traditional musicians in Turkey, Botswana, and Bulgaria, reflecting its importance in their local music. Similarly, the 3:3:2 rhythm, prevalent in African and Afro-diasporic music, including sub-Saharan styles and Afro-Cuban and Latin music, was strongly represented in the musical cognition of dancers from the Sagele village in Mali and musicians and dancers from other African and Afro-diaspora traditions.
“Our study provides the clearest evidence yet for some degree of universality in music perception and cognition, in the sense that every single group of participants that was tested exhibits biases for integer ratios. It also provides a glimpse of the variation that can occur across cultures, which can be quite substantial,” explained Nori Jacoby, the study’s lead author and a former MIT postdoc, who is now a research group leader at the Max Planck Institute for Empirical Aesthetics.
The study also delved into the question of whether these rhythmic biases are influenced by musicianship or a more passive exposure to music. Interestingly, the results indicated that the presence of discrete rhythm categories was not necessarily tied to one’s active musical training or expertise.
Instead, the broad exposure to particular types of music, regardless of active participation in music-making, seemed to be the key factor in shaping these perceptual biases. This finding challenges the notion that only trained musicians develop sophisticated rhythmic perceptions, suggesting instead that passive listening experiences can also significantly influence our internal representations of rhythm.
Another insights from this study is the observation that participants from traditional societies displayed rhythmic biases significantly different from those observed in college students and online participants from the same countries. This discrepancy underscores the profound impact of cultural and environmental factors on cognitive processes related to music.
The findings raise important considerations for psychological and cognitive neuroscience research, which has long been critiqued for its overreliance on WEIRD (Western, Educated, Industrialized, Rich, and Democratic) populations. This study provides concrete evidence that this reliance can lead to an underrepresentation of the vast diversity of human cognitive experiences.
“What’s very clear from the paper is that if you just look at the results from undergraduate students around the world, you vastly underestimate the diversity that you see otherwise,” Jacoby explained. “And the same was true of experiments where we tested groups of people online in Brazil and India, because you’re dealing with people who have internet access and presumably have more exposure to Western music.”
Despite the clear patterns that emerged, the study acknowledges its limitations and the potential avenues for future research. The scope of rhythms explored was limited to simple, periodic three-interval rhythms, leaving questions about more complex or extended rhythmic structures. Moreover, while the study provides strong evidence of culture-specific influences on rhythm perception, it also underscores the need for further investigation into how other factors, such as language or environmental sounds, might interplay with musical rhythm cognition.
The study, “Commonality and variation in mental representations of music revealed by a cross-cultural comparison of rhythm priors in 15 countries,” as authored by Nori Jacoby, Rainer Polak, Jessica A. Grahn, Daniel J. Cameron, Kyung Myun Lee, Ricardo Godoy, Eduardo A. Undurraga, Tomás Huanca, Timon Thalwitzer, Noumouké Doumbia, Daniel Goldberg, Elizabeth H. Margulis, Patrick C. M. Wong, Luis Jure, Martín Rocamora, Shinya Fujii, Patrick E. Savage, Jun Ajimi, Rei Konno, Sho Oishi, Kelly Jakubowski, Andre Holzapfel, Esra Mungan, Ece Kaya, Preeti Rao, Mattur A. Rohit, Suvarna Alladi, Bronwyn Tarr, Manuel Anglada-Tort, Peter M. C. Harrison, Malinda J. McPherson, Sophie Dolan, Alex Durango, and Josh H. McDermott.
