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Charla de Nori Jacoby : “Perceptual priors on musical rhythm revealed cross-culturally by iterated reproduction”

Martes 8 de mayo 18:00hs, Salón Azul (piso 5, salón 502) – Facultad de Ingeniería, J. Herrera y Reissig 565

El Instituto de Ingeniería Eléctrica de la Facultad de Ingeniería de la Universidad de la República invita a la siguiente charla : “Perceptual priors on musical rhythm revealed cross-culturally by iterated reproduction” por Nori Jacoby

Abstract :

Probability distributions over external states (priors) are essential to the interpretation of sensory signals. In many areas of perception and cognition, humans appear to combine current observations with internal beliefs about the environment (the prior) in a process approximating statistical inference. Priors for cultural artifacts such as music and language remain largely uncharacterized, but critically constrain cultural transmission, because only those signals with high probability under the prior can be reliably reproduced and communicated. We developed a method to estimate priors for rhythm via iterated reproduction of random temporal sequences. Listeners were asked to reproduce random “seed” rhythms; their reproductions were fed back as the stimulus, and over time became dominated by internal biases, such that the prior could be estimated by applying the procedure multiple times.
We measured priors on simple rhythms in residents of the United States as well as members of the Tsimané, an Amazonian society with very limited exposure to Western music. We found that priors in US participants showed peaks at rhythms whose time intervals were related by small integer ratios. The modes of the prior were limited to small integer rhythms prevalent in Western music. Priors in Tsimané participants also exhibited modes at integer ratios, but were otherwise qualitatively different from priors in US participants, in ways that are consistent with the structures prevalent in their music. Our results are consistent with the claim that rhythm perception exhibits universal cognitive constraints favoring integer ratios, but indicate that any such constraints are strongly modulated by experience.
I will also present recent results from Botswana, Mali, Brazil, Bolivia, Bulgaria, the United States, South Korea, and Uruguay that suggest that musical exposure, far more than language or geography, profoundly affects the structure of rhythmic perceptual priors. Our method holds promise for characterizing priors in a range of other domains in both audition and vision, including spatial memory, phonetics, and melody.

Bio :

I’m interested in exploring the role of culture in auditory perception, using iterated learning alongside classical psychophysical methods to characterize perceptual biases in music and speech rhythms in populations around the world. My previous work focused on the mathematical modeling of sensorimotor synchronization in the form of tapping experiments as well as the application of machine-learning techniques to model aspects of musical syntax, including tonal harmony, birdsong, and the perception of musical form. I am currently a Presidential Scholar In Society And Neuroscience at Columbia University. Previously, I was a postdoc at the McDermott Computational Audition Lab at MIT, and a visiting postdoctoral researcher in Tom Griffiths’s Computational Cognitive Science Lab at Berkeley. I completed my Ph.D. at the Edmond and Lily Safra Center for Brain Sciences (ELSC) at the Hebrew University of Jerusalem under the supervision of Naftali Tishby and Merav Ahissar, and hold a M.A. in mathematics from the same institution. My research has been published in journals including Current Biology, Nature, Nature Scientific Reports, Philosophical Transactions B, Journal of Neuroscience, Journal of Vision, and Psychonomic Bulletin and Review.