When you're at a party and you meet new people, you'd like to have some way to get to know about them quickly. You can try to talk about sports with people, but not everyone follows sports. You can try to talk about politics, but those conversations can get heated quickly.
Instead, people often ask others about music. Finding out the music that someone else likes seems to give you a lot of information about them, quickly. A study by Peter Rentfrow, and Sam Gosling published in Psychological Science in 2006 found that college students getting to know each other over the Internet are more likely to ask about music preferences than about all other categories of conversation topics combined. This research also found that knowing someone's music preferences allowed students to do a reasonable job of predicting some of the new person's personality characteristics and values. Personality characteristics are the basic dimensions of behavior along which people differ. Values are beliefs and goals that influence how people approach the world.
On top of that, when we find out that someone shares our musical interests, that increases how much we like them. This idea was explored in a paper by Diana Boer, Ronald Fischer, Micha Strack, Michael Bond, Eva Lo, and Jason Lam in the September, 2011 issue of Personality and Social Psychology Bulletin.
In one study, they asked fans of metal or hip-hop music to evaluate descriptions of people who either shared their musical taste, had a different music preference, or had no stated music preference. The participants were asked how much they thought they would like this person. They also rated how similar they thought this person was to them along a variety of personality characteristics and values.
Unsurprisingly, people expressed that they liked a new person better when finding that they shared the same musical taste than when they did not. The amount that someone felt that they would like the new person was based strongly on how much they thought the new person would share similar values rather than similar personality characteristics.
This effect was also observed in a study of college roommates in Hong Kong. In this study, college students who had been rooming together for a few months were asked about music preference, how much they liked each other and a variety of questions about similarities in values. Music preferences predicted similarities in values, which in turn predicted how much the roommates liked each other.
This research suggests that we often ask people about their musical preferences because musical taste serves as an easy indicator of whether we are likely to be similar to new people in ways that will influence how much we like them.
In the end, of course, we can't know from this research whether music influences values or values influence the music people like (or both). That is, people may generally spend time with others who share their values. In these social settings, music is often shared, and the music you hear affects what music you like. So, sharing values could cause music preference.
But the opposite could also be true. Music expresses values. Lyrics have social messages. In this way, listening to particular musical styles could affect people's values. But that is a topic for future research.