Average player traits as predictors of cooperation in a repeated prisoner's dilemma

Many studies have looked at how individual player traits influence individual choice in the repeated prisoner’s dilemma, but few studies have looked at how the average traits of pairs of players influence the average choices of pairs. We consider cognitive ability, patience, risk tolerance, and the Big Five personality measures as predictors of individual and average group choices in a ten-round repeated prisoner’s dilemma. We find that a pair’s average cognitive ability measured by the Raven’s IQ test predicts average cooperation rates robustly and average earnings more modestly. Higher individual cognitive ability also predicts a greater probability of sustaining cooperation in the second round, suggesting that positive reciprocity is more likely among players with higher Raven’s scores. Openness is the only control variable that predicts first-round cooperative behavior.