Expert Can Testify About “Role-Playing In … Sexually Explicit Conversations On The Internet”, Federal Evidence Review, 25 September 2008.
For those of us who have done internet solicitation cases, the concept of role-playing and lying amongst participants is a known serious issue. These cases, as have mine, usually come up because the client shows up to meet the too young for prime time player. Low and behold blow, it's a cop. The defense then is "I didn't believe she was under age, I thought this was all part of the game, and that I was going to meet an adult interested in some role-play sex." Of course these police stings are the ultimate role-playing game.
In United States v. Joseph, 542 F.3d 13 (2d Cir. 2008), the divided court reversed the conviction. In dicta, the court said the court should reconsider the denial of expert testimony about role-playing in internet chat sessions, at retrial.