Interaction, Cooperation and Entrainment in Music: Experience and Perspectives

Abstract

Complex multi-agent behavioral coordination requires the capability of reading and sending subtle sensorimotor messages while performing a joint action towards a shared goal. While progress has been made in the field of social neuroscience, the neurobehavioral mechanisms underlying this kind of interaction, still represent the ‘dark matter’ of cognitive neuroscience. Here we present a series of investigations using ensemble musicians as a test-bed to explore whether motion kinematics and advanced time-series analysis could be used to extract these dynamics. The data we report suggests that the pattern of sensorimotor communication flow between musicians and conductors modulate joint action outcome. Furthermore, we also demonstrate that music ensemble communication is conveyed by movements of different body parts, each one of them containing complementary information needed for coordination. This research line has thus the potential to unravel the multi-scale and multi-channel nature of human sensorimotor communication.

Appendices

Addendum

The Phenomenology of Musical Motricity: Perspectives from an Orchestra Conductor ( by Serâ Tokay )

Own-Body, Kinesthesia and Music

I have always considered particularly useful the phenomenological approach to examine the experience of the musician interpreting the works of the classical repertoire (Tokay, 2016). The instrumentalist’s sensorimotor experience is the “place” where it is possible to bring together the muscular kinaesthesia of the instrumental gesture, the reactivation of the creative intuition of the composer and the empathic resonance resulting from what other musicians and the music-lovers hear. As musician and philosopher, my approach makes use of a theory of the constitutive function of the kinaesthetic system derived from the work of Husserl (1966, 1982), re-oriented, in the direction of a theory of the constitution of the musical sound, insofar as the latter emanates from the sensorimotor activity of the musician. In the following sections, inspired by Husserl’s perspective, I will start discussing the empathic process linking conductor, musicians and audience, I will then continue along the theory of an active production, controlled by the technical savoir-faire of the musicians and by the psychophysical bidirectional link established by the conductor with them. Finally, I will examine the experimental results presented in this chapter from a perspective centered on a theory of the aesthetic object (the musical object insofar as it responds to the artistic norms of harmony). My approach has been developed in opposition to the physicalist reduction of the aesthetic dimension of the musical sound through its analysis in terms of physical properties of acoustic oscillations (von Helmholtz 1990; Xenakis 1971; Boulez 1987).

Empathy and Motor Entrainment

As ‘Einfühlung’ Lipps (1903) defined the lively feeling of being-self which an observer is able to derive from the aesthetic contemplation of another being in movement. He emphasized the direct way in which, without any intermediary judgment, a human being can get immersed in another interior life via observation of the facial and corporeal expressions of the other. Husserl noted that the perceptual recognition of the other requires an appreciation of his body as own body, and he amplified Einfühlung into a dynamic process of co-constitution, the constitution of a common world across the intentions and actions of the self and of others. In the same perspective as the co-constitution of a life-world, but by withdrawing from any transcendental abstraction into a more concrete and bodily field, I take account of those participating in a concert. The movements of the instrumentalists, all of whom are oriented towards the same musical “ideas”, frame the horizon within which the sounds produced take on the value of musical sounds for those in the audience.

Conducting an Orchestra: Coordination or Anticipation?

Here I would like to stress that the integration of the actions of the instrumentalists engaged in playing a musical work depends upon the conductor’s power of anticipation. This anticipation depends upon a motor apprehension of musical time. The result of a quite special technical mastery of the movement of the hands and arms. The speed with which neuromuscular innervation is produced enables the conductor to elicit a haptic analogue of the motor intentions of the instrumentalist. As for the musicians, this anticipation of the kinaesthetic temporality of their own movements by those of the conductor is necessary if one is to grasp the expressive intentions guiding the hands, the gaze, the breath and the bodily posture of the conductor. Without all this it is impossible to understand the affective character of the work, its temporality and its rhythm. According to this view, conducting does not mean to create a hierarchical subordination between the micro-intentions of the instrumentalists and the directional intentions of the conductor. Conversely, there is a continuous alternation between the common goal (harmony) and the singular goals of individual musicians, regulated by a collective desire to play the work as well as possible.

As an example I would like to remember the very start of the 4th Symphony of Schumann, which begins with an A without rhythm in tutti, where a rhythm in ¾ has to be conducted in 6 times interspersed with silences, and in an atmosphere agitated by a continual alternation between forte-piano and crescendo-diminuendo, against a background of rubato. In this context the entire orchestra shares a single telos to intuit a tempo. In such a tempestuous climate each musician has to count his quavers individually, even while sharing the same sense of time, whose unity is established by an empathic relation with the movements of the conductor.

Discussion of Some Experimental Results

• 1. The Driving Force of the Conductor

In this work we have analyzed the kinematic recordings of violin players belonging to a chamber orchestra while playing pieces of Mozart under the direction of two different conductors. As Driving Force, we considered the amount of causality between conductor’s hand and baton velocities and violinists’ bows determined according to Granger’s method. This concept of causality depends on the idea that when one has two variables which are relatively independent (like the respective trajectories of the hands of the musicians and of the conductor), but which depend upon each other in such a way that knowledge of the past values of one trajectory make it possible to predict the value of the other (the conductor getting ahead of the musicians), the first ‘causes’ the second (in Granger’s sense of that word). The comparison of the curves described by a recording of the conductors’ batons and the bows of the violinists show that the invited conductor (who directs in advance) exerts a driving force over the musicians that is both more frequent and stronger than that of the principal conductor. A comparison of the curves recording the bows of the violinists when they play under the direction of the 2 conductors shows that the driving force exerted by the musicians on each other is that much weaker when the driving force of the conductor is stronger and when he figures as the source of the unity of the ensemble. It is plausible that the measure of the conductor’s driving force represent an acceptable quantification of the intersubjective experience that we describe from a phenomenological point of view with the concept of motor empathy acting between the conductor and the musicians.

• 2. The leadership of the conductor as soft entrainment

In an orchestra, the leadership exerted by the conductor consists in getting his musicians to play together. So it should be possible to measure the efficiency of the conductor by the degree of entrainment he instils in the orchestra. But unlike the metronome, which achieves a perfect synchronization without any musical value, the entrainment of the orchestra owes its aesthetic character to a subtle modulation of the dynamics of the entrainment (soft entrainment). The emergence of a collective rhythm on the basis of the individual rhythms of the musicians considered as coupled oscillators is made possible by a phase synchronization in the oscillations, which is mathematically described by the Kuramoto model (Kuramoto 1984). An index of synchronization measuring the soft entrainment of the orchestra is calculated for each measure, and for each conductor. This index, coupled with an evaluation of the artistic quality of the execution, offers a criterion for the efficiency of the leadership of the conductor, one that confirms the score already obtained. The most efficient conductor is the one who exerts the most considerable influence on the musicians. The convergence of the results obtained with the same participants in applying two different mathematical models to the data recorded, the one issuing from econometrics (Granger causality), the other from the analytic mechanics of coupled oscillators (Kuramoto model) proves that anticipation is essential to the direction of an orchestra, whatever the theoretical model employed.

• 3. Extended empathy through ancillary movements

This experiment has looked at significant differences between the ancillary movements of the head of the musicians when the musicians benefit from a normal vision of the movements of the conductor, and when part of them (the first row) are turned by 180°, and can only obtain indirect information on tempo, upbeat, bow movements, nuances, beats, fermata, etc. through the visual observation of the gestures of musicians of the second row that does enjoy a direct vision of the conductor. The recordings in question have been made with the overture to Rossini’s Opera: Il Signor Bruschino. Results were clear: the musicians who are unable to see the conductor make more ancillary movements of the head than when they are able to see her/him. This difference is a measurable characteristic of the movement, a geometrical precursor of the intentional orientation of this movement, indicative of the effort the musicians are obliged to make to mitigate with ancillary movements their less than optimal condition. They are able to compensate for the lack of vision of the conductor with glances at the instrumental movements of their colleagues in the other group facing them. If they nevertheless still remain ensemble, it is only because all the musical information provided by their conductor has been relayed to them by the instrumental movements of this other group of musicians. And so it is that a common behavioural pattern emerges, one that constitutes an inter-subjective field of intentions expressed through gestures encompassing the musicians of both groups. Here, the experimental manipulation achieves an exceptional extension of the inter-subjective space of communication, putting to the test the conductor’s ability to convey his artistic intentions no matter how great the distance to be crossed.

What Can We Learn from These Investigations?

In summary, and from my perspective, these are the main outcome of this investigation:

• (1) In the body of the musician, from which every affectively qualified action proceeds, converge both the experiences of the interpreter and of the auditor.

• (2) Only a conductor capable of an auto-affective anticipation finds herself in a position to promote the emotive and motivating principle necessary for the musician to play well.

• (3) An orchestra confronting its conductor awaits from her a non-verbal motor communication, which in turn depends upon her capacity to surpass the initially inevitable affective confrontation with the orchestra by being ahead of herself through a perfectly mastered gestural strategy.

• (4) As a function of its bodily mastery, our understanding of musical experience requires both a subjective reflexivity of a phenomenological order and an objectivity derived from a neuroscientific approach.