Introduction
Economic models predict that people make rational decisions in bargaining situations. However, emotional aspects, such as trust and fairness, play a big role in social decision making. Within a bargaining situation people try to maximize their own gain (cognitive aspect) but take into account their concerns for others (emotional aspect).
In Event Related Potential (ERP) studies it is shown that receiving an unfair offer elicited higher medial frontal negativity (MFN) amplitudes compared to receiving a fair offer (e.g. Boksem & De Cremer, 2010; Boksem et al., 2011; Van der Veen & Sahibdin, 2010). In the current study we investigate, from a developmental perspective, whether the rejection of a fair offer elicits comparable neural responses within an ultimatum game bargaining situation.
Methods
Participants
17 Adolescents (ages 14-16; M=14.8; 6 M)
19 Young adults (ages 18-26; M=21.0;10 M)
Task
Participants performed
an Ultimatum Game (UG) in which they divided coins between themselves and another player. They decided which of two
divisions of the coins to offer to the other player. The divisions
were 5/5 vs. 7/3 or 3/7 vs. 7/3. The other player accepted or rejected the offer.
Leiden University. The university to discover
Why not? Rejection of Fair Offers in Bargaining Situations:
An Event Related Potential Study
Kiki Zanolie
1 2, David De Cremer
3, & Eveline A. Crone
1 2 4 1 Leiden University, Institute of Psychology; 2 Leiden Institute for Brain and Cognition;3 Erasmus UniversityRotterdam, Rotterdam School of Management; 4 University of Amsterdam, Department of Psychology
c.k.k.zanolie@fsw.leidenuniv.nl
Discussion
Only fair offers rejected in the ultimatum game elicit higher medial frontal negativity amplitudes. These results are found for both adolescents and adults. Our results are comparable to the MFN amplitudes elicited
when receiving an unfair offer in the UG (e.g. Boksem & De Cremer, 2010). As such, neural responses to rejection of a fair offer in an UG bargaining situation are comparable to receiving an unfair offer.
References Boksem, M. A. S., & De Cremer, D. (2010). Fairness concerns predict medial frontal negativity amplitude in ultimatum bargaining. SocNeurosci, 5, 118-128. Boksem, M. A. S., Kostermans, E., & De Cremer, D. (2011). Failing where others have succeeded: Medial Frontal Negativity tracks failure in a social context. Psychophys, 48, 973-979. Van der Veen, F. M., & Sahibdin, P. P. (2011). Dissociation between medial frontal negativity and cardiac responses in the ultimatum game: Effects of offer size and fairness. Cogn Affect Behav Neurosci, 11, 516-525.
This research was supported by a grant from the young academy of the KNAW 500 - 700 ms until response or 2500 ms 3000 ms -RT 1400 - 5000 ms 1400 ms
Results
On feedback onset, when the decision of the other to accept or reject the offer is revealed, there is a significantly higher MFN amplitude after the rejection compared to acceptance of an offer, F(1,33)=8.47, p=0.006. The MFN amplitude is more negative-going when a fair offer is rejected compared to accepted, F(1,33)=16.23, p<0.0001
This pattern is evident for both age groups, although slightly more pronounced in the youngest group (a trend).
0 10 20 30 40 50 60 70 80 90
Fair Unfair Hyper Fair Hyper Unfair
N u m b e r of of fe rs Adolescents Adults 5/5 vs 7/33/7 vs 7/3 3/7 vs 7/35/5 vs 7/3 [µV] 0 10 8 6 4 2 -2 -4 -6 -8 -100 0 200 400 600 [ms]
Cz Fair Accept Adolescents
Reject Adolescents Accept Adults
Reject Adults
Adults and adolescents make an equal number of fair and unfair offers
5/5 vs 7/3 5/5 vs 7/3 5/5 vs 7/3 3/7 vs 7/3 3/7 vs 7/3 3/7 vs 7/3 No No No No Yes Yes Yes Yes 60% 60% 60% 60% 40% 40% 40% 40% 104 trials 104 trials Fair Hyper Unfair Hyper Fair Unfair
Participants were made to believe that they were playing against a real other person. However, they played against a computer which manipulated the rate of rejections and acceptance of the offers.
