Allison Sheridan couldn’t care less about music. Songs of love and heartbreak don’t bring her to tears, complex classical compositions don’t amaze her, peppy beats don’t make her want to dance. For Sheridan, a retired engineer, now a podcaster, who owns 12 vinyl records and hasn’t programed the radio stations in her car, “music sits in an odd spot halfway between boring and distracting.”

Despite coming from a tremendously musical family, Sheridan is part of the roughly 3 to 5 percent of the world’s population that has an apathy toward music. It’s what’s referred to as specific musical anhedonia—different from general anhedonia, which is the inability to feel any kind of pleasure and which is often associated with depression. In fact, there’s nothing inherently wrong with musical anhedonics; their indifference to music isn’t a source of depression or suffering of any kind, although Sheridan notes, “The only suffering is being mocked by other people, because they don’t understand it. Everybody loves music, right?”

Previous research shows that the vast majority of people who enjoy music show an increase in heart rate or skin conductance—where a person’s skin temporarily becomes a conductor of electricity in response to something they find stimulating. Musical anhedonics, however, show no such physiological change to music. A recent study, published in the Proceedings of the National Academy of Sciences, took those findings a step further by studying neural responses to music.

As part of the study, 45 students from the University of Barcelona (where most of the study authors are based) were asked to fill out a questionnaire that helped determine their sensitivity to musical reward. Based on their responses, they were divided into groups of three—people who don’t care for music at all, those who have some interest in music, and those who essentially live and breathe music. The researchers then had them listen to music while measuring their brain activity with an fMRI machine.

For people who enjoy music, activity in the brain’s auditory and reward regions is closely coupled and, for them, hearing a song resulted in joy and pleasure. But, in the brains of people with specific musical anhedonia, researchers found that the auditory and reward regions of the brain simply didn’t interact in response to music. As a control, to make sure that musical anhedonics responded to other stimuli, researchers also had participants play a gambling game and found that winning money activated the brain’s reward system just fine.

Meanwhile, in the brains of hyper-hedonics—people on the other end of the musical spectrum—researchers saw the strongest transfer of information between the auditory and reward parts of the brain. “It shows that the experience that you have for music is linked to this type of neural response pattern—the more you have it, the more interaction there is between those two systems, the more you are likely to feel pleasure to music,” says Robert Zatorre, a cognitive neuroscientist at McGill University in Montreal and one of the authors of the study. “These are people who say life would be unimaginable without music.”

Sitting at that musically inclined end is Paul Silvia, who is often immersed in post-rock, shoegazer rock, electronic, or jazz music. “I hear music in my mind a lot, and I can get chills from this imagined music,” says Silvia, a psychology professor at the University of Carolina at Greensboro, who experiences chills in response to music several times a day. In fact, it was this response that got Silvia to begin studying chills almost a decade ago.

“Chills are fascinating,” says Silvia, because “there’s a difference between some song you like coming on the radio and emotions from music that are deep.” It’s that feeling of wanting to cry when you hear a particularly moving piece or feeling your heart soar as notes get larger and more grandiose. “It seems to be part of this whole cluster of feelings that people find very hard to have words for,” Silvia says.

As part of his research, Silvia found that some people were more prone to get chills and experience goosebumps when listening to music, and those people also tended to be more open to new experiences. “People with high openness to experience are much more creative and imaginative, and they get these kinds of awe-style experiences so much more often,” Silvia says. “They’re much more likely to play an instrument, they go to concerts, they listen to a wider range of music, they listen to more uncommon music. They just get more out of music.”

These kinds of findings can help researchers further explore different pathways to the reward system. “Just as with musical anhedonia, where people respond to everything except music, there are some people who don’t respond to anything except music,” says Zatorre. “Maybe they can learn to activate the reward system through music,” he says. “And if they can do that, maybe they can transfer that knowledge to a different domain, whether it’s control over their reward system, control over their mood state, or control over their pleasure response.”

Zatorre says his findings have also helped musical anhedonics get well-meaning friends and family off their back. “People came to me saying, ‘I’m glad you’ve given us scientific proof, because now I can tell my friends to stop bugging me about music. It doesn’t do anything for me.’”