Nowak has found that it can be more advantageous to alternate between giving and matching. In generous tit for tat, the rule is “never forget a good turn, but occasionally forgive a bad one.” You start out cooperating and continue cooperating until your counterpart competes. When your counterpart competes, instead of always responding competitively, generous tit for tat usually means competing two thirds of the time, acting cooperatively in response to one of every three defections. “Generous tit for tat can easily wipe out tit for tat and defend itself against being exploited by defectors,”
