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A popular myth associates creativity with the right side of the brain, but expert jazz musicians, such as Pat Metheny, may rely more on the left side of the brain when improvising.
enlarge A popular myth associates creativity with the right side of the brain, but expert jazz musicians, such as Pat Metheny, may rely more on the left side of the brain when improvising.

Roberto Panucci/Corbis/Getty Images

There is a popular myth that divides people into the ‘left brain’ and ‘right brain’ categories, with the former being analytical and logical, while the latter being creative and innovative. The reality, of course, is much more complicated than that, and a new study of brain images of improvised jazz guitarists is a prime example. Researchers at Drexel University found that while the right hemisphere is associated with creativity in fairly inexperienced jazz musicians, experts with high mastery of improvisation skills actually rely primarily on the left hemisphere. They described their results in a recent article in the journal NeuroImage.

Co-author David Rosen is a musician and scientist who started playing the piano at the age of eight before picking up the bass guitar in high school. (Rosen’s band, Nakama, just released a new EP, for those wanting to discover new musical vibes while we’re all under isolation orders.) Because improvisation—defined as “the spontaneous invention of melodic solo lines or accompaniments”—is a defining feature of jazz Rosen thought it would be an excellent opportunity to explore the role of the brain, not just in creativity, but more broadly in musical perception and expression.

“I think there are a lot of interesting questions to ask about [musical] perception, both for people who listen to music and for people who perform music,” Rosen told Ars. “The brain is the part that makes us most human and makes us feel those emotions. It’s almost impossible to quantify the altered state we enter when we perform or listen to the music we enjoy most and that means the most to us as individuals. Ultimately, we’re trying to ask very focused scientific questions about what it means to share in that musical experience.”

In the area

Jazz musicians often talk about moments during live performances when all the band members are “in the zone”, as it were, reacting and reacting to each other, rather than being more internally focused on their own independent creative choices. That is the essence of improvisation for Rosen.

“Mastery of jazz relies heavily on one’s ability to constantly improvise in all sorts of different scenarios with different musicians,” Rosen said. “And improvising in jazz is really difficult because of the large number of different chords. The chord sequences can be quite complex, with changes happening very quickly.” From a neuroscientific perspective, that’s the kind of task that puts a heavy cognitive load on the brain, yet master jazz musicians can perform this demanding task in real time thanks to years and years of rigorous training.

A jazz guitarist improvises while his brain activity (EEG) is recorded.
enlarge A jazz guitarist improvises while his brain activity (EEG) is recorded.

University of Drexel

How exactly do you measure a vague concept like ‘creativity’ with some degree of robustness? Rosen et al. For their research, they used an established method known as the ‘consensual assessment technique’, in which experts rate material – be it music, film, etc. – on different types of scales. In this case, a panel of four expert musicians and educators assessed how creative the subjects’ improvisations were, the aesthetic appeal of the performances, and the subjects’ technical ability.

All three measurements were collected independently and were found to be highly correlated, providing the team with a measurable quality score for the experiment. As for the expert panelists, their “inter-rater reliability” across all three scales was very high. “So we have an indication that these people are consistent in their measures,” Rosen said. “Without that reliability, we’d just say, ‘Okay, score random people’s opinions.'”

Thirty-two jazz guitarists – some highly experienced, some relative novices – took part in the study. Each subject was asked to improvise on six jazz lead sheets while connected to an EEG machine. Their playing was accompanied by programmed drums, bass and piano. The resulting 192 recordings were then played back to the expert panel, which judged them for creativity and other associated qualities. then Rosen et al† compared the highest and lowest rated recordings with the recorded EEGs to see which brain regions showed more activity.

Early results showed that there was more left hemisphere activity for highly rated performance on the creativity scale, with more right hemisphere activity for those lower rated performance. According to Rosen, that finding makes sense once you factor in a musician’s degree of experience.

While the right hemisphere is associated with adapting to new, unfamiliar situations, the left side of the brain is generally more involved in ordinary or routine tasks. “If you do something over and over, you get really good at that task,” Rosen said. “But that doesn’t necessarily tell us when the expert has a new or creative experience while they’re doing the task. In our behavioral models, we saw that expertise contributed quite a bit of variance in predicting the scores of the improvisation classifications.”

If expertise was the main driver behind the observed effect, then when the team statistically controlled for level of expertise (especially when it came to public performance), they found little difference in the brain scan data. Instead, there were significant differences in right hemisphere brain activity (especially the frontal region) between performances rated highly creative and performances rated lower creativity ratings.

In short, experts were rated highest by the panel, even though they approached the task of jazz improvisation with the most common routines. Rosen attributes this in part to the fact that, for example, a novice has to go through 16 bars of music on a lead sheet quarter note by quarter note, while an expert can find patterns, such as an ii-VI progression. “That allows them to approach the test with a reduced level of that cognitive control,” he said. Creativity is thus associated with the right hemisphere when we are dealing with an unfamiliar situation and associated with the left hemisphere when we have a lot of experience with the task at hand.

“If creativity is defined in terms of the quality of a productsuch as a song, invention, poem or painting, the left hemisphere plays a key role,” said Rosens co-author John Kounios, director of Drexel’s program for applied and cognitive brain sciences. “However, if creativity is understood as being a person power to deal with new, unfamiliar situations, as is the case with novice improvisers, the right hemisphere plays the leading role.”

A double process

This experiment will contribute to a growing body of research at Rosen’s new music technology startup, Secret Chord Laboratories, which is developing software to predict how listeners will respond to a particular piece of music. The company is currently targeting the record industry, which is always looking for the next hit single. (Rosen describes its mission as “an interdisciplinary exploration of the neuroscience of music.”)

The core technology grew out of a previous study Rosen did with Georgetown University’s Scott Miles on music perception, which examined which sound patterns produce a pleasure response in the brain, if any. They looked at Hot 100 songs on the Billboard charts, from “Johnny B. Goode” in 1958 to Nirvana’s “Smells Like Teen Spirit” in 1991. “We analyzed every single chord of each of those songs and we did a statistical test to see if those mapped in the top quartile had a different level of what we call “familiar surprise,” in terms of the harmonic structure,” Rosen said.

They found that the most popular songs had a high level of harmonic surprise, defined as points where the music deviates from the listener’s expectations — using relatively rare chords in verses, for example, rather than simply holding on to, letting we say, the standard C major chord progression (C, G, F). The best songs follow that harmonic surprise with a catchy common chorus. The resulting patents—since expanded to include rhythm, melody, timbre, and lyrics, as well as harmonies—led to the founding of the company.

Rosen and his colleagues plan to analyze the jazz guitarist’s data to investigate the neural correlates of so-called “flow states.” He also thinks it might be possible to design an experiment to test his hypothesis that jazz musicians engage in a form of “switching,” collecting various tricks and techniques that they can use if they briefly pause during an impromptu performance. lose track. “Once we can have people back in the labs, we can add really weird chords, or have music that doesn’t match the lead sheet, and see how quickly they react when they’re thrown out,” he said.

“My hypothesis is that [experts] would be able to return to the brain state they were in more quickly than a novice could,” Rosen said. “The twin process isn’t just that beginners use all the control and executive functions and experts don’t use any of them. It’s about the interaction of those systems, and which ones prevail at the different levels of expertise.”

DOI: NeuroImage2020. 10.1016/j.neuroimage.2020.116632 (About DOIs).

By akfire1

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