Trial outcomes (reward, R; temptation, T; sucker, S; punishment, P) in 24 trials/day (mean±SEM) from rats playing iterated Prisoner’s Dilemma (IPD) or Stag hunt (SH) with a Stooge who follows a random response strategy (IPD-Random, A), Win-stay/Lose-shift (IPD-WSLS, B), or Tit-for-tat (IPD-TFT, C; SH-TFT, D). See Figure 1 for experimental details. Rats were pre-treated i.p. with saline (open bars) or 0.1 mg/kg oxytocin (OT, closed bars). Asterisk indicates significant effect of OT.