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Have you always wanted to write a pop music classic? Good news! Prof. Dr. Stefan Kölsch and PhD student Vincent Ka Ming Cheung from the Max-Planck-Institute for Cognitive and Brain Sciences in Leipzig have decoded part of successful music’s DNA. Songs like James Taylor’s Country Road, UB40’s Red, Red Wine or The Beatles’ Ob-La-Di, Ob-La-Da are irresistible thanks to their perfect combination of anticipation and surprise. Pleasure in music depends on both past and future expectations.

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“It’s fascinating how people are able to enjoy a piece of music, if for no other reason than how chords have been arranged over time,” Vincent Cheung says. “Songs that we like are probably songs that strike a fine balance between our knowing what’s going to happen and the surprise of something we weren’t expecting.” The neuroscientist then adds:

“”If we understand how music activates our pleasure system in the brain, we would also be able to explain why we often feel better when listening to music. Even when we may be feeling melancholic.”

Neuroimaging and machine learning

As part of their research, the experts used a machine learning model to analyze a total of 80,000 chords from 745 classic American billboard pop songs. This enabled them to mathematically quantify uncertainty and surprise. This is one of the elements that distinguishes this study from an earlier one. Previously, reactions to surprising musical passages were only taken into account when a piece of music was actually heard for the first time, Cheung explains. He and his colleagues, on the other hand, have also taken into account “the uncertainty of a former expectation.”

We are all familiar with this: the first bar of a piece of music is heard and we recognize the song straightaway (faster than Shazam can). According to Cheung, the researchers have removed elements such as text, melody and rhythm from the songs in order to prevent this from happening. They just kept the chord sequences of the original pop songs. As a result, the hits were no longer recognizable for the test subjects.

Cheung explains the uniqueness of their research:

“Our study combines neuroimaging and machine learning in order to find out how the anticipation of music makes music enjoyable and also reveal the immediate underlying neural networks.”

Mix of surprise and familiarity

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The result: when test subjects were relatively sure which chords they could expect to hear next, they enjoyed being surprised. In other words, their expectations were compromised. Conversely, the researchers also proved that if test subjects were not sure what they could expect next, they would prefer the next chords to be familiar rather than surprising.

“Although composers have known this intuitively for centuries, the underlying processes of how expectation evokes joy in music were still unknown,” Kölsch confirms. “In the past, most studies have only looked at the effects of surprise on musical pleasure, but not at uncertainty when it comes to listeners’ expectations.

The scientists used brain scans from functional Magnetic Resonance Imaging (fMRI) for their research. They also discovered that the perception of musical pleasure is reflected in three areas of the brain. The amygdala (for processing external impulses). The hippocampus (for controlling influences and memory). And the auditory cortex (auditory center). These regions process emotions, knowledge and memory and sound. By contrast, the activity in the so-called nucleus accumbens, where the anticipation of reward is processed, merely reflects the uncertainty of the listeners. This also came as a complete surprise to the researchers. Up until then, it was thought that this part of the brain (linked to the human reward system) also played a role in processing pleasure in music. It is Cheung’s view that further research will eventually reveal the way in which these brain processes come together and how they exactly lead to delight in music.

Dance and film

In short, the results of the researchers show that the sense of pleasure influences the areas of the brain that process sounds, emotions and memories. “And that musical pleasure depends on the dynamic interaction between past and future expectations. Our fundamental human ability to predict something is therefore an important mechanism whereby abstract audio sequences acquire an emotional significance. By doing so, they transform into a universal cultural phenomenon that we call ‘music’,” the researchers state.

Another important outcome of the study is that people’s expectations of chords are gained implicitly over the course of their lives. In this respect, our previous experiences in music determine our expectations. Take for example, listening to the radio or the sound in bars and restaurants. These can also have an impact on the kinds of music we enjoy.

After considering their findings, the study’s authors encourage future brain research to pay more attention to the combined role of uncertainty and surprise. One could, for instance, examine why other art forms such as dance and film have such great value for people. The results could also be used for improving artificial algorithms that generate music. Or for helping composers to write music or predicting musical trends.

Make it easier, don’t ditch it

The next step for the neuroscientists is to examine how information flows across various parts of the brain while listening to music. They want to know why and how it  happens that people who listen to music sometimes get goosebumps. Cheung anticipates the outcome of that research to be even more significant: “We think there is great potential in combining computer modelling and neuroimaging not only in order to understand why we enjoy music, but also what it means to be human.”

Getting back to music, are we any closer to the moment when an automated composition kit for music might be made based on Cheung’s findings? “Our results could be used to improve artificial algorithms for generating music or simplify compositions.” However, this is not yet a substitute for human composition. Because, after all, a perfect song needs lyrics, melody and an uplifting rhythm.

The study was recently published in the journal Current Biology.