Dual system in the ultimatum game: evidence from the process dissociation procedure

The ultimatum game is a classic paradigm for measuring fairness preferences. Dual-system theories indicate that people's preferences in the ultimatum game are a result of the interaction between automatic System 1 and controlled System 2. In this study, we recruited 137 and 164 college students for two experiments. Experiment 1 used the process dissociation paradigm to examine how cognitive load influences System 1 processing. Experiment 2 used rational belief to engage System 2 processing. Results revealed that (1) high cognitive load enhanced the contribution of System 1 but did not affect the contribution of System 2 and (2) priming rational belief enhanced the contribution of System 2 but did not affect the contribution of System 1. These findings suggest that the mechanisms behind fairness preferences by indicating that the ultimatum game is driven by two separate systems.