Equal status in Ultimatum Games promotes rational sharing

Area of Science:

• Behavioral Economics
• Evolutionary Game Theory
• Experimental Economics

Background:

• Standard Ultimatum Game (UG) experiments reveal non-rational human behavior, with frequent rejection of low offers and acceptance of fair proposals.
• Theoretical models suggest evolutionary explanations for UG behavior in structured populations where individuals play both roles.

Purpose of the Study:

• To investigate Ultimatum Game behavior in a novel experimental setup where subjects simultaneously fulfill both proposer and responder roles within a fixed population structure.
• To compare experimental results from structured UG with predictions from evolutionary game theory and findings from traditional, well-mixed UG experiments.

Main Methods:

• Subjects participated in simultaneous, dual-role Ultimatum Game experiments with a fixed interaction structure.
• Analysis focused on acceptance levels of responders and offer strategies of proposers within this structured environment.

Main Results:

• Responders exhibited acceptance levels closer to rationality compared to single-role UG experiments.
• Proposers adapted their offers based on their environment, demonstrating a best-response-like strategy.
• Status equality in structured UG promoted rational sharing, while population structure led to fairer offers than in well-mixed populations.

Conclusions:

• Simultaneous dual-role play in a structured Ultimatum Game significantly alters behavior compared to single-role experiments.
• Findings challenge existing evolutionary game theory predictions for UG, highlighting the impact of social structure and role integration on economic decision-making.