Jamie - Suzy has been my best friend for years so I know her well. When she comes to my room after a date I'll inevitably ask if she kissed the lucky man she was out with--that's my right as her best friend. Squinting my eyes and watching her face, I think of myself as a pretty good judge of her body language. She smiles sweetly and looks me in the eyes, "Of course not." The next day, however, I may hear a different story. "You know how I told you I didn't kiss Bob? Well, I did. I just wished that I hadn't and so I didn't want to tell you." It always makes me laugh. No matter how many times this has happened, I can't always be sure if she is telling the truth the night before. So now I ask her if she kissed him, and then ask her what she's going to tell me in the morning. We laugh about it; it's a fun part of our friendship. But our behavior also demonstrates the "truth bias" of Interpersonal Deception Theory. I wouldn't ever assume that Suzy was lying to me. But is she always telling the truth? Obviously not--I have proof from her own mouth. Of course, I'm sure she's not deceiving me the morning after--after all, she's my best friend (truth bias, again)!