But if you really are a selfish player, and you have somehow persuaded the other player to trust you and play "deny" then you should definitely play "confess" t

But if you really are a selfish player, and you have somehow persuaded the other player to trust you and play "deny" then you should definitely play "confess" to maximize your payoff. With selfish players there is no way to move to ("deny","deny") in a one-shot Prisoners' Dilemma. Cultural change cannot help unless it amounts to a change in payoffs. [The story would have been different in a coordination game with multiple Pareto-ranked equilibria where a change in beliefs can move you from a bad equilibrium to a good equilibrium.]