Taking it easy when playing ultimatum game with a Down syndrome proposer: Effects on behavior and medial frontal negativity

ABSTRACT

The ultimatum game (UG) is an endowment sharing game in which a proposer suggests a division of an asset to a recipient, who must accept or reject it. Economic studies showed that despite recipients usually rejecting unfair offers, perception and reaction to unfairness are highly dependent on who is the proposer. Event-related potentials (ERPs) commonly detected in UG games are the medial frontal negativity (MFN), a component detected in recipients facing unfair offers, and the P300, a component related to attentional and memory processes. Given this, we aimed to investigate the behavioral and ERP responses of healthy people playing the UG game with Down syndrome (DS) and typical development (TD) proposers. Nineteen subjects participated in this study. The UG behavioral data were similar to previous studies. ERP analysis showed no MFN in participants facing unfair offers. A higher P300 amplitude was detected when participants faced fair offers from TD compared to DS fair offers. We also found a positive correlation between P300 amplitude for TD offers and self-esteem scale score. Together these findings indicate that insertion of an atypical player in the UG led to changes in participants’ perception and expectancy of the game.

KEYWORDS:

• Down syndrome
• ultimatum game
• MFN
• P300

Acknowledgments

GGR was supported by a CAPES Master grant; and JHTE was supported by a scientific initiation grant PIBIC/CNPq [number 157936/2014-7]. PSB is a CNPq research fellow and is supported by National Council for Scientific and Technological Development [CNPq 311641/2015-6]. We acknowledge two anonymous reviewers for insightful feedback on an earlier version.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by CAPES Master grant, scientific initiation grant PIBIC/CNPq [number 157936/2014-7], National Council for Scientific and Technological Development [CNPq 311641/2015-6].