Ultimatum Game Task¶
HED Task ID: hedtsk_ultimatum_game
Also known as: Ultimatum Game, UG
Proposer offers a division of an endowment; responder accepts or rejects. Rejection of unfair offers indexes inequity aversion and strategic punishment.
Description¶
Two players divide a sum of money. The proposer suggests a division; the responder accepts (both get the proposed split) or rejects (both get nothing). Typically played with computer-controlled offers varying from fair (50-50) to unfair (90-10). Unfair offers activate the anterior insula (negative emotion, inequity aversion) and are rejected at high rates, even at personal cost. The task demonstrates the interplay between emotional reactions and rational economic considerations in social decision-making.
Inclusion test¶
Procedure |
A proposer splits a sum of money; the responder can accept (both keep their shares) or reject (neither gets anything). |
Manipulation |
Offer fairness (proportion offered); endowment size; proposer identity (human, computer); cultural context. |
Measurement |
Rejection rate as function of offer; minimum acceptable offer; proposer strategy (modal offer); fMRI anterior insula activation to unfair offers. |
Variations¶
Variation |
Description |
Justification |
|---|---|---|
Standard Ultimatum |
Two-player, single-shot; proposer offers, responder accepts/rejects. |
Canonical: proposer offers split, responder accepts/rejects |
Strategy Method |
Responder specifies minimum acceptable offer for all possible offers. |
Responder states acceptance threshold for all possible offers; different elicitation |
Multi-Round Ultimatum |
Repeated interactions with same partner; reputation effects. |
Repeated rounds; tests learning and adaptation |
Third-Party Punishment |
Observer can punish unfair proposer at personal cost. |
Observer can punish unfair proposer; adds external enforcement |
Proposer Competition |
Multiple proposers compete with offers to one responder. |
Multiple proposers compete for responder; changes market structure |
Asymmetric Information |
Endowment size unknown to one party. |
Responder does not know pie size; different information structure |
Stake Variation |
Varying endowment size from $1 to $100+. |
Systematically varies total pie size; tests stake sensitivity |
Anonymous vs. Identified Partners |
Varying social distance and information about partner. |
Social identification changes accountability |
Ultimatum with Earned vs. Windfall Endowment |
Effort-based vs. random allocation. |
Endowment from effort vs. luck; changes perceived legitimacy |
Cognitive processes¶
This task engages the following cognitive processes:
Key references¶
{‘authors’: ‘Güth, W., Schmittberger, R., & Schwarze, B.’, ‘year’: 1982, ‘title’: ‘An experimental analysis of ultimatum bargaining’, ‘venue’: ‘Journal of Economic Behavior & Organization’, ‘venue_type’: ‘journal’, ‘journal’: ‘Journal of Economic Behavior & Organization’, ‘volume’: ‘3’, ‘issue’: ‘4’, ‘pages’: ‘367-388’, ‘doi’: ‘10.1016/0167-2681(82)90011-7’, ‘openalex_id’: None, ‘pmid’: None, ‘citation_string’: ‘Guth, W., Schmittberger, R., & Schwarze, B. (1982). An experimental analysis of ultimatum bargaining. Journal of Economic Behavior & Organization, 3(4), 367-388.’, ‘url’: ‘https://doi.org/10.1016/0167-2681(82)90011-7’, ‘source’: ‘crossref’, ‘confidence’: ‘high’, ‘verified_on’: ‘2026-04-20’}
{‘authors’: ‘Sanfey, A. G., Rilling, J. K., Aronson, J. A., Nystrom, L. E., & Cohen, J. D.’, ‘year’: 2003, ‘title’: ‘The Neural Basis of Economic Decision-Making in the Ultimatum Game’, ‘venue’: ‘Science’, ‘venue_type’: ‘journal’, ‘journal’: ‘Science’, ‘volume’: ‘300’, ‘issue’: ‘5626’, ‘pages’: ‘1755-1758’, ‘doi’: ‘10.1126/science.1082976’, ‘openalex_id’: None, ‘pmid’: None, ‘citation_string’: ‘Sanfey, A. G., Rilling, J. K., Aronson, J. A., Nystrom, L. E., & Cohen, J. D. (2003). The neural basis of economic decision-making in the Ultimatum Game. Science, 300(5626), 1755-1758.’, ‘url’: ‘https://doi.org/10.1126/science.1082976’, ‘source’: ‘crossref’, ‘confidence’: ‘high’, ‘verified_on’: ‘2026-04-20’}
{‘authors’: ‘Liu, Y., Lin, W., Xu, P., Zhang, D., & Luo, Y.’, ‘year’: 2015, ‘title’: ‘Neural basis of disgust perception in racial prejudice’, ‘venue’: ‘Human Brain Mapping’, ‘venue_type’: ‘journal’, ‘journal’: ‘Human Brain Mapping’, ‘volume’: ‘36’, ‘issue’: ‘12’, ‘pages’: ‘5275-5286’, ‘doi’: ‘10.1002/hbm.23010’, ‘openalex_id’: None, ‘pmid’: None, ‘citation_string’: ‘Feng, C., Luo, Y. J., & Krueger, F. (2015). Neural signatures of fairness-related normative decision-making in the ultimatum game: A coordinate-based meta-analysis. Human Brain Mapping, 36(2), 591-602.’, ‘url’: ‘https://doi.org/10.1002/hbm.23010’, ‘source’: ‘crossref’, ‘confidence’: ‘high’, ‘verified_on’: ‘2026-04-20’}
Recent references¶
{‘authors’: ‘Gabay, A. S., Radua, J., Kempton, M. J., & Mehta, M. A.’, ‘year’: 2014, ‘title’: ‘The Ultimatum Game and the brain: A meta-analysis of neuroimaging studies’, ‘venue’: ‘Neuroscience & Biobehavioral Reviews’, ‘venue_type’: ‘journal’, ‘journal’: ‘Neuroscience & Biobehavioral Reviews’, ‘volume’: ‘47’, ‘issue’: None, ‘pages’: ‘549-558’, ‘doi’: ‘10.1016/j.neubiorev.2014.10.014’, ‘openalex_id’: None, ‘pmid’: None, ‘citation_string’: ‘Gabay, A. S., Radua, J., Kempton, M. J., & Mehta, M. A. (2014). The Ultimatum Game and the brain: A meta-analysis of neuroimaging studies. Neuroscience & Biobehavioral Reviews, 47, 549–558.’, ‘url’: ‘https://doi.org/10.1016/j.neubiorev.2014.10.014’, ‘source’: ‘crossref’, ‘confidence’: ‘high’, ‘verified_on’: ‘2026-04-20’}
{‘authors’: ‘Henrich, J., Boyd, R., Bowles, S., Camerer, C., Fehr, E., Gintis, H., McElreath, R., Alvard, M., Barr, A., Ensminger, J., Henrich, N. S., Hill, K., Gil-White, F., Gurven, M., Marlowe, F. W., Patton, J. Q., & Tracer, D.’, ‘year’: 2005, ‘title’: ‘“Economic man” in cross-cultural perspective: Behavioral experiments in 15 small-scale societies’, ‘venue’: ‘Behavioral and Brain Sciences’, ‘venue_type’: ‘journal’, ‘journal’: ‘Behavioral and Brain Sciences’, ‘volume’: ‘28’, ‘issue’: ‘6’, ‘pages’: ‘795-815’, ‘doi’: ‘10.1017/s0140525x05000142’, ‘openalex_id’: None, ‘pmid’: None, ‘citation_string’: ‘Henrich, J., Boyd, R., Bowles, S., et al. (2005). “Economic man” in cross-cultural perspective: Behavioral experiments in 15 small-scale societies. Behavioral and Brain Sciences, 28(6), 795–815.’, ‘url’: ‘https://doi.org/10.1017/s0140525x05000142’, ‘source’: ‘crossref’, ‘confidence’: ‘high’, ‘verified_on’: ‘2026-04-20’}
{‘authors’: ‘Liu, Y., Lin, W., Xu, P., Zhang, D., & Luo, Y.’, ‘year’: 2015, ‘title’: ‘Neural basis of disgust perception in racial prejudice’, ‘venue’: ‘Human Brain Mapping’, ‘venue_type’: ‘journal’, ‘journal’: ‘Human Brain Mapping’, ‘volume’: ‘36’, ‘issue’: ‘12’, ‘pages’: ‘5275-5286’, ‘doi’: ‘10.1002/hbm.23010’, ‘openalex_id’: None, ‘pmid’: None, ‘citation_string’: ‘Feng, C., Luo, Y. J., & Krueger, F. (2015). Neural signatures of fairness-related normative decision-making in the ultimatum game: A coordinate-based meta-analysis. Human Brain Mapping, 36(2), 591–602.’, ‘url’: ‘https://doi.org/10.1002/hbm.23010’, ‘source’: ‘crossref’, ‘confidence’: ‘high’, ‘verified_on’: ‘2026-04-20’}