In the wiretapped phone conversation between Roland Burris and Robert Blagojevich, the former governor’s brother and chief fundraiser, Burris repeatedly utters a nervous laugh—seven times, in fact, as indicated by “(chuckles)” in the transcript of the six-and-a-half-minute tape.

We asked Robert Provine, a neuroscientist, psychologist, and author of Laughter: A Scientific Investigation (Viking; 2000), to listen to the Burris-Blagojevich audiotape and read over the transcript and tell us why Burris (chuckles) so much.

Provine says he can’t say for sure, but he suggests that Burris displays “the behavior of a stressed person.”

At a couple of points, Provine notices that Burris laughs while speaking, what Provine calls “laughspeak”—a signal that someone is “usually trying to defuse a delicate situation.” Oh, you mean like Chicago politics?

Photograph: AP Photo/Belleville News-Democrat/Derik Holtmann