Which choice is the rational one? An investigation of need for cognition in the ultimatum game

• Large and heterogeneous sample of 1326 participants.
• First study to investigate need for cognition in relation to the ultimatum game.
• Actual money as payout in the ultimatum game.
• Surprisingly, higher rejection rates for two indicators of rational decision-making.
• Rational (accept) vs. emotional (reject) interpretation falls short.

Recent studies have identified several factors, such as negative affect or fairness concerns, that contribute to explaining the seemingly irrational behavior of receivers in the ultimatum game, namely rejecting unfair offers despite the corresponding personal loss. The opposite behavior, accepting offers, has often been attributed to rational decision-making, as predicted by rational choice theory. Based on this assumption, we investigated long reaction times as a behavioral variable and need for cognition as an individual differences variable as indicators of thoughtful and rational decision-making. To our surprise, we found both reaction times and need for cognition to predict rejection, rather than acceptance of unfair offers. Our results challenge the interpretation of acceptance vs. rejection in terms of rational vs. emotional accounts.