Music makes us move even when we don't like it

That groove response is so strong it is even found in people with musical anhedonia, those who take little or no pleasure from music.

The article's lead author is Isaac Romkey, a PhD student in the Department of Psychology. He writes in the journal PLOS One that recent research shows the two aspects of groove, pleasure and urge to move, while usually closely correlated, may in fact be separable.

To test this, Romkey and his co-authors compared groove responses to more than 50 short pieces of music in people with musical anhedonia and non-anhedonic controls. Participants with musical anhedonia were only included if they derived pleasure from other aspects of life, like food and sex, and if they exhibited appropriate reward responses across other metrics. The researchers also ensured participants were not depressed and had intact pitch and beat perception. Participants listened to short pieces of music designed to elicit a groove response and varied in rhythmic complexity. After each piece, they were asked to rate how much pleasure they experienced and how much it made them want to move.

"Normally, we would expect to see an inverted U-shaped response to rhythmic complexity, meaning that we want to move to music that is of medium complex rhythms as opposed to music that is very simple or very complex," Romkey explains.

Based on this, the authors hypothesized that people with anhedonia would show lower pleasure ratings but preserved urge to move ratings for groovy music.

However, they found no differences in either pleasure or urge to move in anhedonics compared to controls. More importantly, they showed that for people with anhedonia, the urge to move appears to drive their experience of pleasure. That suggests that the blunted pleasure sensation found in people with musical anhedonia is compensated by the urge to move.

"In the musical anhedonia group, we expected to see a flattening of that U-shaped curve, but that is not what we saw. That implies that for those with musical anhedonia, they derive pleasure from the urge to move. More generally, it suggests that the urge to move may itself generate pleasure."

Same response, different sources

The causes of musical anhedonia remain understudied, but Romkey says it appears to be heritable. He does note that the urge to move has been linked to the dorsal striatum, a part of the brain that is linked to motor functions, while pleasure is more associated with the ventral striatum, which regulates reward, motivation and goal-directed behaviour.

"For future studies, we are going to look at differences in functional and structural connectivity in the brain between anhedonics and controls in the dorsal and ventral striatum using imaging techniques including MRI and magnetoencephalography," he says.

Co-authors include Nicholas Foster, Simone Dalla Bella and Virginia Penhune at Concordia and Tomas Matthews, PhD 21, of Aarhus University.