Ultimatum Game

Saturday afternoon, a café. You sit across from someone you've never met before — the experiment matched you. A facilitator brings an envelope: $100 in cash. 'You two can split this. The other person sets the ratio. You can only accept or reject. If you reject, both get nothing. One round only. You'll never see each other again.' The woman across from you is in her 30s, well-dressed, calm. She writes on a card and turns it toward you: 'Me $80, You $20.' The facilitator looks at you. Twenty dollars is free money. You could spend it right here on a coffee. But her taking $80 — something about it stings. Rejecting means you both lose. She loses her $80 too. Your $20 and her $80 are both balanced on your next word.