You may have come across a viral video on Facebook from "deception expert" Rick Lax, who invites you to participate in a little pop quiz involving numbers. If you haven't seen it, watch the 1-minute-plus video right now . (I'd embed the video in this post for you but I'm not sure I'm allowed to do so.) If you were like me, you thought of the number 7 at the end. Of course, this is exactly the number Lax wanted you to come up with. So how does it work? Or does it work at all? There was some discussion about this urgent matter on Facebook in the Psychological Methods Discussion Group . The moderator of that group, Uli Schimmack, who also thought of 7, suggested this was the result of priming. But then he questioned his explanation: " We don't know because we don't know how often he gets it right? We just see 1 million shares. It is like reading Psych Science . We only see the successes." This makes sense. In theory there could be a mas