Do you talk to yourself? Don’t sweat it: Scientists say you’re not alone. And the ways in which you chatter to yourself, both in your head and out loud, are changing what neuroscientists know about the human brain.

Writing in Scientific American, psychologist Charles Fernyhough reveals why we’re our best conversational partners. Scientists have only recently learned how to study self-talk — and it’s opening up exciting new avenues of research.

It turns out there are two ways of chatting yourself up. In “inner speech,” you speak to yourself without making sound. With “private speech,” you do the same thing, just out loud.

This chatter serves varied purposes: It can help people control themselves and relate to others. But it’s notoriously hard to study. So Fernyhough and colleagues figured out some inventive ways to prompt people to talk to themselves as they lay inside a functional magnetic resonance imaging, or fMRI, scanner.

When they studied the brains of people who talked to themselves internally, the team noticed that spontaneous inner speech activates a different part of the brain than words that the participants were asked to say aloud. And people whose self-talk takes the form of a monologue seem to activate different brain areas than those who carry on a dialogue in their heads.

It’s too early to draw conclusions about how and why people talk to themselves. But the research suggests that self-talk could one day clue scientists in to how different regions of the brain work, alone and in concert. Perhaps, Fernyhough suggests, the words we say to ourselves could one day unlock bigger neurological and psychological secrets. Until then, there’s plenty to discover — and endless private conversations to be had.