In: Economics
Prisoner 1 has to build a belief about what choice Prisoner 2 is going to make, in order to choose the best strategy. If Prisoner 2 confesses, he will get either -8 or 0, and if he lies he will get either -10 or -1.
It can be easily seen that Prisoner 2 will choose to confess, since he will be better off. Therefore, Prisoner 1 must choose the best strategy given that Prisoner 2 will choose to confess.
Prisoner 1 can either confess (Prisoner 1 confess, which pays -8) or lie (Prisoner 1 lie, which pays -10).
The rational thing to do for Prisoner 1 is to confess. Proceeding inversely, we analyze the beliefs of Prisoner 2 about Prisoner 1’s strategies, which gets us to the same point: the rational thing to do for Prisoner 2 is to confess. Therefore, [Prisoner 1confess, Prisoner 2 confess] is the Nash equilibrium in this game (UNDERLINED -8-8).