As the holidays near, we eagerly anticipate spending time with our nearest and dearest. When we gather in the warmth of the hearth, we’re so happy to see them – that is, until we end up at each other’s throats.
How do we encourage our families to behave themselves in a way that reflects how, deep down, they truly love each other? Turn to game theory, the science of strategic thinking.
Game theory underpins everything from negotiations over the broadcasting rights of big sports fixtures to schemes for improving organ donation. The mathematics of the prisoner’s dilemma – one of the field’s most famous problems – have even been applied to the hunt for new life forms in space.
You already know more about it than you realise: whenever you find yourself considering what you should do in terms of how someone else might respond, that’s game theory. But brushing up your know-how could help you preserve family harmony over the holidays. After all, if game theory was able to help avert nuclear apocalypse during the cold war, there’s an outside chance it could get your lazy uncle to help for once.
Who will host?
The solution to this problem may appear simple. In the lead-up to the holidays, have everyone vote: Grandma’s house or Aunt Laurel’s. (You’ll have to draw straws for who gives Grandma the bad news.)
But what if there are three choices? Game theorists say you should use a Borda count. Each person ranks their preferences: 1, 2, 3. Then you add up the numbers. The host with the lowest score wins. Variants of the Borda count are used in some national elections – and even important international matters such as selecting the winner of the Eurovision Song Contest.
Who conducts the Borda count is another question. Maybe break out the straws again?
Who brings what?
That greasy green bean casserole gets thunked down on the table every year – your cousin’s contribution to the festive feast. Many people have delicious alternatives they would love to provide, but no one wants to hurt her feelings, so those woeful wilted beans keep coming back. How can you break free from this pattern without being insulting?
People expect others to behave consistently when they encounter the same situation. But whether a situation is considered the same or different can depend on how it is presented. In game theory, this is known as framing, and it can cause people to radically alter their behaviour. When told something is a business interaction, for instance, people behave more selfishly; if told the exact same interaction is social, they are more altruistic.
So switch frames. Seize on a change of time or venue. “Since we’re at Dad’s house this year, let’s change dishes.”
The last bit of dessert
If your family members aren’t arguing about politics, they’re probably squabbling over who gets the last roast potatoes or the final sliver of Stilton. How can you keep the bickering to a minimum? Game theorists recommend using I Cut, You Pick. If there are two people hankering after the last of the yule log, one slices and the other chooses.
Or, if you’re facing your first holiday after a marital separation, you might use the same technique to peaceably allocate the living room furniture, the still unused china and the fondue set. When the person doing the dividing is motivated to make the portions equally good, it’s more likely that both parties will end up satisfied. And that applies whether it’s cake or crystal.
Too much food?
It’s always the same: every year you’re begging people to take home leftovers. Everyone brings way too much food. Why? Look at their incentives. There’s no real penalty for bringing an excessive amount, but somebody might be offended if they bring too little. So change the incentives.
It works. In 2002, Ireland brought in a 15 cent tax on plastic grocery bags. Within weeks, plastic bag use dropped by 94 per cent. In England, it is down about 80 per cent since a plastic bag fee was introduced in October 2015.
How can you harness the power of incentives to reduce the extra food? Give a prize to the cook whose dish is totally gone, or make the guest with the most leftovers host next time. Now it’s not a measure of one’s love, it’s a game.
Stop playing tag in the living room!
The kids are misbehaving after dinner. Mum yells, “If you don’t stop, we’re leaving!” They ignore her, and minutes later the antique lamp is in pieces. Why didn’t the children listen? They knew an overstuffed Mum didn’t really want to leave. Her warning was a non-credible threat.
The principle is the same when far more is at stake. One argument for holding nuclear weapons is to deter other countries from using theirs. But what if the other country strikes first? You can’t retaliate if you’ve been wiped out. To maintain a credible threat, the UK has “letters of last resort” aboard its four nuclear submarines: instructions for what to do in that situation. Since enemies don’t know where the subs are, or what the instructions say, the danger of retaliation is real.
For Mum though, it might be enough to threaten to make the kids do the dishes. If they know she is more than happy to follow through, it’s more likely to have an impact.
Uncle Larry never helps
Everyone else is busy straightening up the house, but Uncle Larry is on the couch playing Candy Crush. How can you make him do his fair share? It’s no use telling him that everyone thinks he should help. People pay more attention to empirical expectations, what others do, than normative expectations, what others say they should do.
In an experiment where people had a sum of money they could share with others, telling them that “most people donate” encouraged more giving than telling them “other people think you ought to donate”.
You can put empirical expectations to work with Larry. Make a point of having someone clean up around him, so he can see them doing it. He might just feel obliged to pitch in.
You are about to put your feet up when you sense an argument brewing over whether to play charades or put on Elf for the umpteenth time. What to do? Use an auction. Those in the opposing camps can bargain by offering to do chores. Whoever makes the best offer – finish washing the dishes and tidy up the kitchen – gets to pick.
Game theorists recommend auctions for everything from hawking old junk from the attic to selling off bands of radio frequency to broadcasters. They are the best way to figure out who really cares more.
Getting the kids to share
One final trick if all else fails: the ultimatum game. Two kids get a small box of chocolates to share. How do they divvy them up? Ask Sally to keep some for herself and offer the rest to Richard. But add a consequence. If Richard thinks she’s being unfair, you will step in, divide the chocolates and take a few for yourself. That’s a credible threat, because they know you like chocolate.
A similar scenario applies in trade union negotiations or international trade deals. If the terms aren’t fair enough for everyone, they all lose out on the benefits of striking a deal.
Experiments show that people will reject a financial offer, despite losing money in the process, if they think they are getting a raw deal. Even when it comes at our own expense, we all take pleasure in punishing someone who is acting unfairly.
This article appeared in print under the headline “How to win at Christmas”