Cognitive multiplicity in polyrhythmic pattern performance.

Abstract

The performance of 4 forms of a 4:3 polyrhythm by 3 experienced percussionists using a synchronous protocol was examined. The percussionists were able to selectively apply different production models to their performance, and the authors show that these can be systematically elaborated in cognitive terms using structural equation modeling. All models were found to be variants of a general hierarchical standard model, which is based on a clock pulse, motor delay variables, subdivision variables, and certain basic covariance assumptions. Size of cognitive ground (fundamental clock pulse) was the primary variable affecting production; control processes were predominantly hand independent. The ground-associated hand showed better accuracy and consistency than the nonground (figure) hand for withinhand intervals. In contrast, ground hand motor delay variances were larger than corresponding figure hand variances.

Modelling rhythmic function in a musician post-stroke

“…In response to the tone, he was asked to tap one of two force-sensitive keys (Honeywell microswitch PK89133) placed before him on a flat table, using first the right and then the left hand in alternate runs. The keys were connected to an IBM 486 computer equipped with special recording and data analysis software, as previously described by Pressing and co-workers [47][48][49][50]. The measurement accuracy of the equipment was between 1-2 ms.…”

“…This model was originally enunciated by Wing and Kristofferson [68,69] and has received substantial empirical support across a range of experimental contexts [19,50,57,[65][66][67]. For self-generated, isochronous tapping, the basic model comprises two independent components.…”

Cross-cultural studies of musical pitch and time

“…Polyrhythms place non-trivial cognitive and motor demands on performers and listeners [50,52]. In Africa, polyrhythms create perceptual entrainment effects in ritual; effects that are linked to multiplicity of perception.…”

“…Perceptual organization varies with the individual and the speed, use of accents, attentional strategy, and the frequencies of tones used in the two streams [53]. Figure-ground assignments are interpreted as ''unidirectional coupling between oscillators'' [50], and the model of timing builds on that of Wing and Kristofferson [54].…”

“…Considering the production of rhythm, Pressing et al [50] draw attention to the presence of polyrhythms in world musics. Polyrhythm is a form of rhythmic dissonance, that is, time is divided by two or more differently rated strata.…”