Bargaining and Trust: The Effects of 36hr Total Sleep Deprivation on Socially Interactive Decisions

Though it is well known that sleep loss results in poor judgment and decisions, little is known about the influence of social context in these processes. Sixteen healthy young adults underwent three games involving bargaining (‘Ultimatum’ and ‘Dictator’) and trust, following total sleep deprivation (TSD) and during rested wakefulness (RW), in a repeated measures, counterbalanced design. To control for repeatability, a second group (n=16) was tested twice under RW conditions. Paired anonymously with another individual, participants made their simple social interaction decisions facing real monetary incentives. For bargaining, following TSD participants were more likely to reject unequal-split offers made by their partner, despite the rejection resulting in a zero monetary payoff for both participants. For the trust game, participants were less likely to place full trust in their anonymous partner, again affecting final payoff. Overall, we provide novel evidence that following TSD, the conflict between personal financial gain and payoff equality is focused on unfavourable inequality. This results in the rejection of unfair offers, at personal monetary cost, and the lack of full trust, which would expose one to being exploited in the interaction. As such, we suggest that within a social domain a rational decision may not prevail over more emotional options following TSD, which has fundamental consequence for real-world decision making involving social exchange. Key Words: Sleep loss, trust, bargaining, social preference, interaction