The Jazz Turnaround: A Back-to-Back Paradigm for Studying Improvisation

Musical improvisation involves extremely complex cognitive processes—with performers engaging in rapid, in-the-moment decision-making coupled with focussed motor attention, all-the-while maintaining awareness of the other musicians and the music. It’s no wonder that it captivates the interest of Dr Freya Bailes, a music researcher at the University of Leeds, who presented a talk on the cognitive mechanisms involved in improvisation at Goldsmiths College on the 1st of February 2018.

Who’s leading who?

One aspect of improvisation that may not automatically spring to mind is leadership. Traditionally, within certain types of improvisation such as jazz music, leadership may arise from a conductor or more likely, the lead-player within the ensemble. These individuals show where the music is going (rhythmically, harmonically, and dynamically) through subtle changes in their playing and (often fantastically cryptic!) gestures and visual cues. But how does leadership occur for two people improvising freely?

This was one of the core focuses for Bailes and Dean in a recent study investigating cognitive processes in improvisation. The researchers paired professional pianists, instructing them to perform six, three-minute improvisations. However, there was a catch! The performers had to play back-to-back at separate MIDI pianos, rendering them unable to use visual cues while improvising—Bailes wanted exchange of auditory information only.

UntitledBack-to-back pianists—the set-up used in Bailes’ experiment. (Source)

Limited directions for the format of the six improvisations were given. Two of the improvisations were labelled as completely free, one had a dynamic structure (quiet, loud, quiet), one was to be centred around a pulse, one was instructed to be led by Performer 1, and the last was to be led by Performer 2. The researchers were interested in how responses to each other’s playing would influence the development of leadership roles between the two performers. In addition, they were curious to discover the performers’ perceived leadership roles, i.e. who each performer believed was leading the improvisation at different points in the piece. Thirty minutes after performing, the performers listened back to their improvisations and rated who they felt influenced the music most in each section. They found that aural cues alone were sufficient for performers to identify who was taking the lead.

Sweat for science

Bailes and Dean aimed to probe both conscious and unconscious measures of the performers’ experiences. Therefore, in addition to the conscious measure (leadership rating), they employed an unconscious measure by recording the physiological arousal of performers while improvising. Arousal is considered a component of the emotional response triggered by listening to music (Khalfa et al. 2002; Rickard, 2004). They measured arousal by recording changes in skin conductance (SC)—a type of electrodermal activity caused by variations in the sweat glands, controlled unconsciously by the sympathetic nervous system (Khalfa, Isabelle, Jean-Pierre, & Manon, 2002).

Untitled.png SC.pngSkin conductance (SC) is captured via skin electrodes placed on the fingertips or, when confronted with jazz pianists, on the left ankle. (Source)

SC is often measured on the fingertips—a bit problematic for pianists! Instead, Bailes and Dean measured SC on the pianist’s left ankle, as the performers were able to keep that part of their body still (the right ankle was left free for pedalling). Interestingly, it was previously hypothesised that SC might increase more during transitions in the improvisations, as those points in the music require increased attention and effort to develop a new pattern in the music (Dean & Bailes, 2016). An analysis of a case study for one duo found that SC typically did increase during transitions, e.g. when a new dynamic section began. One player’s SC matched the musical structure of the improvisations, while the other player had an overall greater variability in SC but did not always follow the shape of the music. In general, improvisation could intensify a performer’s arousal state by focussing attention on the moment-by-moment decision making, and awareness and reaction to the other performers’ actions. That’s a lot to think about at once!

How about you, the audience?

In addition to obtaining leadership perception from the performers, Bailes also investigated listeners’ (specifically non-musicians) perceptions on the leadership roles during the improvisation. It seems that Bailes enjoys tackling difficult topics as she herself described ‘perception of leadership in improvisation’ as an impossible task for non-musicians! It was the researchers’ turn to improvise, as they devised an alternative approach—to ask an open question to the non-musician listeners: “Indicate where any significant changes in sound occur within the improvised piece of music”. The piece they listened to was taken directly from the recordings of the professional musicians used for their study on leadership roles (Dean & Bailes, 2016). The questions asked were left deliberately open to interpretation as they didn’t want to bias any perceptions. Participants were asked to listen to the piece at a computer and move the mouse to indicate change. Large changes in music were to be indicated by faster mouse movements, and smaller changes by slower movements.

In addition to this, non-musicians were asked to report the level of perceived arousal expressed during the piece of music. By moving the mouse along a scale (moving up the scale = higher arousal), participants mapped out the level of arousal over the time-course of the music. Here, the team were interested in whether outside-listeners were sensitive to the physiological arousal of the performers. By comparing the outside-listeners’ perceived arousal with the SC of the performers over the time course of the music, Bailes and Dean were able to analyse the data for any correlations that may support their hypotheses.

Bailes and Dean developed a couple of interesting hypotheses concerning outside-listeners. Firstly, they predicted the perceptions of the outside-listeners would align with the performers’ perceptions of changed leadership, however, this was not the case. Instead, the case study analysis of one duo revealed that the listeners’ perception of changes in sound aligned with the computational segmentation of each pianist’s performed key velocity. Their second hypothesis was that the outside-listeners’ perception of arousal would align with the performers’ level of physiological arousal, as measured by their SC level, over the time-course of the music. Interestingly, a mixed result was found regarding their second hypothesis. In the same case study, Performer 2’s skin conductance correlated with the listeners perceptions of arousal, and yet in the same piece of music, performer one’s skin conductance did not align with the listeners perceptions. Bailes suggests that perhaps individual differences in SC (Performer 1 was more prone to sweating!) may have weakened the link between perceptions and physiological measures of arousal.

Untitled.png arousalDiagram illustrating the levels of arousal measured in the experiment (Bailes, 2018)

The research presented by Bailes and Dean display some interesting details. Their research looked at a range of intriguing questions regarding improvisation, from leadership roles to arousal and the interactions between performers’ perception and physiological changes and non-musician’s perceptions. Bailes and Dean’s research suggests that when two performers are playing together, aural cues alone are enough to allow performers to agree on who was leading the music at any given point. However, their case study also found no evidence to support some of the hypotheses proposed, potentially highlighting the intricacy of investigating such concepts. It seems that when you’re fascinated by researching impossible tasks, you can’t always expect straightforward results—but that’s all part of the fun.

Nicholas Feasey, Taylor Liptak, and Alex Lascelles


Bailes, F. (2018). Cognitive processes in improvisation [Powerpoint slides]. Retrieved from

Dean, R. T., & Bailes, F. (2016). Relationships between generated musical structure, performers’ physiological arousal and listener perceptions in solo piano improvisation. Journal of New Music Research, 45(4), 361-374.

Khalfa, S., Isabelle, P., Jean-Pierre, B., & Manon, R. (2002). Event-related skin conductance responses to musical emotions in humans. Neuroscience letters, 328(2), 145-149.

Rickard, N. S. (2004). Intense emotional responses to music: a test of the physiological arousal hypothesis. Psychology of music, 32(4), 371-388.

Rowe, M. (2011, May 13). Jazz Code. [Web log post]. Retrieved January 20, 2018, from


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