The Sign of Silence: Negotiating Musical Identities in an Improvising Ensemble

Group musical improvisation, as a spontaneous process of collaborative creativity effected through non-verbal social interaction, is a unique psychological phenomenon and universal capacity. Existing studies focus on improvisation among professional jazz musicians, often using qualitative methods. However, improvisation transcends genres and levels of training or experience, and existing qualitative data are rarely analyzed as discourse. We compare findings from studies of jazz musicians’ improvising with interview data from free improvisers from varied backgrounds focused on their improvising together (n = 10). The ways jazz musicians construct improvising in talk were distinct from the constructions of this more diverse group, suggesting a specifically professional discourse. By focusing on accounts of deciding whether to play, the ambiguity of musical contributions in the non-verbal context of playing is highlighted. Analysis indicates that musical acts within improvisation are interpreted by the musicians involved in ways that inherently support or resist particular identities. The unique creative, communicative and social process of musical improvising in groups can therefore best be understood when the entirety of improvisational practice and its various contexts are acknowledged. Future research can best recognize the diversity of, and change in, what improvisation can encompass with continued discursive investigation of group improvising

A nonlinear updating algorithm captures suboptimal inference in the presence of signal-dependent noise

Bayesian models have advanced the idea that humans combine prior beliefs and sensory observations to optimize behavior. How the brain implements Bayes-optimal inference, however, remains poorly understood. Simple behavioral tasks suggest that the brain can flexibly represent probability distributions. An alternative view is that the brain relies on simple algorithms that can implement Bayes-optimal behavior only when the computational demands are low. To distinguish between these alternatives, we devised a task in which Bayes-optimal performance could not be matched by simple algorithms. We asked subjects to estimate and reproduce a time interval by combining prior information with one or two sequential measurements. In the domain of time, measurement noise increases with duration. This property takes the integration of multiple measurements beyond the reach of simple algorithms. We found that subjects were able to update their estimates using the second measurement but their performance was suboptimal, suggesting that they were unable to update full probability distributions. Instead, subjects’ behavior was consistent with an algorithm that predicts upcoming sensory signals, and applies a nonlinear function to errors in prediction to update estimates. These results indicate that the inference strategies employed by humans may deviate from Bayes-optimal integration when the computational demands are high

Cognitive and affective judgements of syncopated musical themes

This study investigated cognitive and emotional effects of syncopation, a feature of musical rhythm that produces expectancy violations in the listener by emphasising weak temporal locations and de-emphasising strong locations in metric structure. Stimuli consisting of pairs of unsyncopated and syncopated musical phrases were rated by 35 musicians for perceived complexity, enjoyment, happiness, arousal, and tension. Overall, syncopated patterns were more enjoyed, and rated as happier, than unsyncopated patterns, while differences in perceived tension were unreliable. Complexity and arousal ratings were asymmetric by serial order, increasing when patterns moved from unsyncopated to syncopated, but not significantly changing when order was reversed. These results suggest that syncopation influences emotional valence (positively), and that while syncopated rhythms are objectively more complex than unsyncopated rhythms, this difference is more salient when complexity increases than when it decreases. It is proposed that composers and improvisers may exploit this asymmetry in perceived complexity by favoring formal structures that progress from rhythmically simple to complex, as can be observed in the initial sections of musical forms such as theme and variations

Rhythm quantization for transcription

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Cerebellar and basal ganglia contributions to interval timing

Previous studies have suggested that the cerebellum and basal ganglia may play a critical role in interval timing. In the first part of the chapter, we review this literature, focusing on production and perception tasks involving intervals in the hundreds of millisecond range. Overall, the neuropsychological and neuroimaging evidence consistently points to the involvement of the cerebellum in such tasks; the evidence is less consistent with respect to the basal ganglia. In the second half of the chapter, we present an experiment in which patients with either cerebellar or basal ganglia pathology were tested on a repetitive tapping task. Unlike previous studies, a pacing signal was provided, allowing an evaluation of variability associated with internal timing, motor implementation, and error correction. The results suggest a dissociation between the two groups: the patients with cerebellar lesions exhibited noisy internal timing while the gain in error correction was reduced in Parkinson patients. In combination with previous work, these results indicate how the cerebellum and basal ganglia may make differential contributions to tasks that require consistent timing