NPR Science reporters Alix Spiegel and Lulu Miller explain to Ira Glass how they smuggled a rat into NPR headquarters in Washington, and ran an unscientific version of a famous experiment first done by Psychology Professor Robert Rosenthal. It showed how people’s thoughts about rats could affect their behavior.

Alix Spiegel tells the story of Robert Dixon, who's in a maximum security prison in Vacaville California and is unlikely to ever get parole because of his score on the psychopath test. The test also is called "the checklist" or, more formally, the PCL-R, which stands for "Psychopathy Check List—Revised." Alix tells the story of its creation and reports that the man who created the test, Bob Hare, is concerned at how it's being used today in the criminal justice system.