NOTICE
CERSS Colloquium on March 5th was cancelled due to state of emergency against novel coronavirus (COVID-19) by Governor of Hokkaido.

Date & Time: 2020. 3. 5 (Thu) 14:45-16:15

Location: Hokkaido University, Faculty of Humanities and Human Scieces, room E304

Speaker: Vincent Buskens (Utrecht University, Prof. )

Title: Explaining Rejections of Unfair Offers: Comparing Preference and Emotion-Based Response Behavior in Ultimatum and Impunity Games using EEG and EMG Measurements

Abstract：
It is still under debate whether rejections of unfair offers in Ultimatum-type games are more driven by preference-related arguments such as inequality aversion or emotion-related arguments such as anger.
One reason for this debate is that there exists conflicting evidence on rejection rates of unfair offers in Impunity Games. In Impunity Games, the proposer keeps the proposed share if the responder rejects the offer, while the responder still loses it. Thus, inequality is increased by rejection rather than reduced as in the Ultimatum Game and the proposer cannot be financially punished by the responder. Bolton and Zwick (1995) find much lower rejection rates of unfair offers in the Impunity Game than in the Ultimatum Game favoring the preference-based explanation, while Yamagishi et al. (2009) find comparable rejection rates between the two games favoring the emotion-based explanation. In an innovative design in which proposers are not informed on whether they play Impunity or Ultimatum Game, we compared response behavior in these two games in 48 one-shot trials while, for 40 responders, measuring brain activity (using electroencephalography, EEG), facial expressions (using electromyography, EMG), and skin conductance. We also measure subjective emotion measures and social value orientations for all 78 responders. We find that rejection rates of unfair offers are much lower in the Impunity Game than in the Ultimatum Game and also that rejection is related to social value orientations, confirming the preference-based explanation. Still, we also find that unfair offers induce anger (based on subjective reports of subjects even more anger for the Impunity Game than for the Ultimatum Game) and that negative emotions, based on EMG and EEG measures, induce more rejection behavior in the Ultimatum Game.
Nevertheless, these emotion-based explanations of rejections in Ultimatum Games do not translate into rejections for the Impunity Game suggesting that incentive related arguments are not overtaken by the emotional reactions.

Susumu Ohnuma, Director, Center for Experimental Research in Social Sciences
e-mail: ohnuma@lynx.let.hokudai.ac.jp