AMERICA'S National Public Radio has just started a new blog on race, and the title is a term from linguistics: Code-Switch. We've touched on code-switching before. Linguists typically use it to mean the instant and frequent switching between two distinct languages, like Spanish and English among many Puerto Rican New Yorkers. But Gene Demby, in explaining the new blog's name, says

we're looking at code-switching a little more broadly: many of us subtly, reflexively change the way we express ourselves all the time. We're hop-scotching between different cultural and linguistic spaces and different parts of our own identities — sometimes within a single interaction.

Many readers will be familiar with this phenomenon:

Your mom or your friend or your partner calls on the phone and you answer. And without thinking, you start talking to them in an entirely different voice — still distinctly your voice, but a certain kind of your voice less suited for the office. You drop the g's at the end of your verbs. Your previously undetectable accent — your easy Southern drawl or your sing-songy Caribbean lilt or your Spanish-inflected vowels or your New Yawker — is suddenly turned way, way up.

Public figures do it too. Mr Demby offers this 2009 video of Barack Obama in a chili-dog restaurant in a black neighborhood in Chicago. His voice is distinctly that of a black man comfortable in black Chicago, not that of the man who would give a soaring, formal inaugural address soon after. Asked if he needed any change for his chili dog, he tells the cashier, "Naw, we straight!"

A certain kind of politician can get away with this. I always enjoyed watching Bill Clinton dial up his southern-fried accent as needed for a barbecue or down for a speech to the United Nations. But I cringed just as much watching Hillary Clinton try to do the same. Here she is quoting some gospel lyrics to a black church in Selma, Alabama in 2007. Her corny southern accent sounds more like George Wallace, Alabama's segregationist governor and presidential candidate, than any of the black churchgoers in the audience. Americans like their politicians to have a common touch, but it should't fit like a crooked fake Groucho Marx moustache.

A good comedian can, of course, call in accents as needed, and the black comedy duo of Key and Peele are very good comedians. Watch the two accents gradually deepen as they negotiate their black identities through an order at a soul-food restaurant.

Click through to Mr Demby's post to see another Key and Peele skit, in which code-switching acts more like a shield than a sign of solidarity.

Language is a proxy for identity, and so code-switching is an apt metaphor for handling more than one identity. That makes it a great name for a blog on race, and I'll look forward to following it.