- Motivations to reciprocate cooperation and punish defection are calibrated by estimates of how easily others can switch partners

Adjusted odds ratio of each predictor for the decision to switch partners Estimates of how much each predictor affected the decision to switch partners, when controlling for the five others. An odds ratio greater than 1 indicates a greater likelihood of partner switching; an odds ratio less than 1 indicates a lower probability of partner switching. Bars are 95% confidence intervals. Reciprocation by the participant = percent of 3P that the participant returned to the truster (0–100%). Punishment by the partner = whether the truster punished the participant’s response (1, 0). Trust = P, the number of points the participant sent to the responder (0–100). Defection by the responder = the responder defected or reciprocated on the participant (1, 0). Amount paid to punish the responder = number of points the participant paid to punish the responder (0–50).