Experimental evidence

Two more empirical research projects involved music-psychological experimentation.

First, we created realistically sounding versions of some phrases which are characteristic of the jembe rhythm Manjanin and manipulated the subdivision timing patterns, including the original one (short–medium–long) as well as isochronous and inversed ones (long–medium–short). We played them to dancers and drummers in Mali and checked whether they could hear the difference amongst the different manipulations, and whether they liked them or not. Both participant groups reliably recognized almost all manipulations and aesthetically preferred those closest to the original. Here is a pdf of the paper.

Finally, we used the experimental paradigm of finger-tapping, where research participants listen to simple rhythms while tapping along in best possible synchrony on a small percussion instrument. The systematic deviations between what they hear and how they tap along during this process provide information about the participants’ perceptual prototypes. We found that all tested groups exactly reproduced a 1:1 (isochronous) stimulus and performed quite well on a 2:1 rhythm (which could be notated as a quarter plus and eighth note), but strongly diverged from each other in their response to a stimulus where the two note are related by a complex ratio that falls in between 1:1 and 2:1 (namely, 58:42), as is typical for the two-stroke ostinato accompaniment rhythms of many prominent drumming rhythms from Mali, such as Manjanin and Wolosodòn, among others. German and Bulgarian musicians massively distorted this "swung" ratio towards 2:1, whereas Malian musicians reproduced it with near perfect precision and reliability. This suggests that the Malian but not Bulgarian and German musicians have a perceptual rhythmic category for fast rhythms whose prototype does not fall on a small integer ratio and cannot be mapped to an isochronous fastest pulse. Have a look at a pdf of the study's publication.