Monday, May 04, 2009

Is beat induction special? (Part 5)

This year several new insights were published on the phenomenon of beat induction.* Beat induction is the cognitive skill that allows us to hear a regular pulse in music to which we can synchronize. It allows us to dance and make music together. Hence it is considered a skill that must have contributed to the origins of music. Without it, making music would be quite difficult.

Most of these recent studies try to support (or falsify) the criteria that beat induction, as a cognitive skill that allows for music, should fulfill — it should at least be a) special to music (domain-specific), b) develop spontaneously (or be innate), and c) be uniquely human (human-specific).

In earlier blogs I discussed some recent evidence that beat induction is active in newborns, providing support for the innate criterion. This week two new studies appeared in Current Biology challenging the human-specific criterion (see also BBC News or Dutch radio).

The evidence is compelling (and will cost me two bottles of wine). Both the studies of Schachner et al. and Patel et al. show that it is unlikely due to chance that one cockatoo and twentyfive parrots synchronized to music.

Especially Patel and Iversen’s tempo controlled experiment is interesting because there it could be studied whether the cockatoo is actually listening to the music. Although the current paper is only reporting on bouts where the cockatoo synchronized (selected by the researchers !), some tests show this is not simply due to chance. However, synchrony in about ten percent of all recordings is not a lot for a bird that seems to enjoy dancing and almost constantly moves to the music.

Furthermore, it is surprising that Schacher et al. state that none of their bird-subjects was 'explicitly trained to produce movement in response to acoustic material.' This is at least not true for the cockatoo Snowball who was analyzed in both studies. As Patel et al. write, Snowball (likely) learned his foot-lifting behavior from a previous owner making arm movements in synchrony while dancing (to music).

Snowball needs to be in the mood for dancing and has to be enthusiastically spoken too to start him up. It suggests an important role of the owner/trainer being present at the experiment (by the way, it is unclear whether the researchers were actually present at these recording sessions). In addition, during at least half of the experiments the current owner was nodding her head (apparently not systematically influencing the results). It seems Snowball deserves a more formal, yet attractive setting in the near future.

Overall, it makes me interpret these data as learned behavior and a mimicking phenomenon, more than an innate or spontaneously developing form of beat induction that humans have.

Nevertheless, it interesting to think what makes parrots and cockatoos receptive to beat induction, instead of our closer relatives like chimpanzees or bonobo’s? Patel suggests the vocal learning hypothesis: the capacity for entrainment as a by-product of selecting for vocal-mimicking, with both needing modality-specific links between auditory and motor representations. Others believe it is the particular rhythmic chorusing (as a behavior of complex social groups) that is the source of the behavior. I’m currently simply ‘confused’, the best a new empirical finding can do!

ResearchBlogging.orgSchachner, A., Brady, T., Pepperberg, I., & Hauser, M. (2009). Spontaneous Motor Entrainment to Music in Multiple Vocal Mimicking Species Current Biology DOI: 10.1016/j.cub.2009.03.061

ResearchBlogging.orgPatel, A., Iversen, J., Bregman, M., & Schulz, I. (2009). Experimental Evidence for Synchronization to a Musical Beat in a Nonhuman Animal Current Biology DOI: 10.1016/j.cub.2009.03.038

* Beat induction is also referred to as Beat Perception and Synchronization (BPS; Patel, 2008), Sensorimotor Synchronization (SMS; Repp, 2005), or as audio entrainment (cf. Large & Jones, 1999).

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