Ultimatum Game, Fairness Norms
The Last Slice
The Last Slice is an Ultimatum Game and Fairness Norms scenario. The core lesson: Fairness norms override pure rationality in one-shot bargaining. A stranger offers you $100, but only if you can agree with another stranger on how to split it. One of you proposes the split. DecisionPlay maps the players, payoffs, and equilibrium dynamics that shape how this situation typically resolves.
The situation
A stranger offers you $100, but only if you can agree with another stranger on how to split it. One of you proposes the split. The other accepts or rejects. Reject, and both get nothing. You get to propose. What do you offer?
Background
Classical game theory predicts the proposer should offer $1 and the responder should accept, because $1 is better than $0. In real experiments, proposers offer around 40% on average, and responders reject offers below 20-30% even though rejecting costs them money. Why? Because humans treat fairness as a consumable good, getting cheated feels bad enough that people will pay to punish the cheater, even when the cheater is a stranger they will never see again.
What this reveals
The fairness premium
Humans pay real money to punish perceived unfairness, and this is not a bug. It's a social-coordination feature that evolved because it sustains cooperation over the long run.
How to counter it: Don't assume your counterpart is a rational wealth-maximizer. Assume they will reject 'insulting' offers even at personal cost, and price that in.
A question to sit with
When was the last time you walked away from a deal that would have made you better off, because the other side was being unfair? What did that cost you, and was it worth it?
Frequently asked questions
- What game theory concept does The Last Slice illustrate?
- The Last Slice illustrates Ultimatum Game, Fairness Norms. Fairness norms override pure rationality in one-shot bargaining.
- What is the situation in The Last Slice?
- A stranger offers you $100, but only if you can agree with another stranger on how to split it. One of you proposes the split. The other accepts or rejects.
- What does The Last Slice reveal about how people decide?
- The fairness premium. Humans pay real money to punish perceived unfairness, and this is not a bug. It's a social-coordination feature that evolved because it sustains cooperation over the long run.
- How do you avoid the trap in The Last Slice?
- Don't assume your counterpart is a rational wealth-maximizer. Assume they will reject 'insulting' offers even at personal cost, and price that in.
- What is the research behind The Last Slice?
- Classical game theory predicts the proposer should offer $1 and the responder should accept, because $1 is better than $0. In real experiments, proposers offer around 40% on average, and responders reject offers below 20-30% even though rejecting costs them money. Why?
- How long does The Last Slice take to play?
- About 6 min, at intro difficulty, across 4 decision points. It runs in your browser with no account and no sign-in.
Keep exploring
More Classical Game Theory scenarios, or browse all scenarios. New to this? Start with how DecisionPlay works or the game theory glossary.
Topics: ultimatum, fairness, bargaining, behavioral-econ