The Ultimatum Game is one in which Player A is given a sum of money to split with Player B. Player A gets to determine how that money is divided between them, and Player B can either accept the proposal or reject it. If Player B rejects the proposal, neither player gets anything. A rational, utility-maximizing person should logically accept the proposal regardless of the split. After all, if they reject it, both players go home with nothing. And even if Player A is stingy (for example, splitting $1,000 as $900 for himself and $100 for Player B), Player B would still end up with $100 he didn't have going into the experiment. And yet, studies show that when Player B's share is less than 30% of the total, the proposal is often rejected and both players end up with nothing. Why? Because most people have an inherent sense of fairness and unfairness, to the point that they would disadvantage themselves rather than let someone else get away with being unfair to them.

The Public Goods Game is another exercise in which players are each given a sum of money and must secretly decide how much to contribute to a public pot, which will then be multiplied and divided among all the players. For example, let's say there are four players (A, B, C, and D), each of them has $1,000, and the multiplier is 2. Logically, it's in the group's interest to contribute ALL their money because that would mean $4,000 total would be in the pot, it would get multiplied by 2 (to $8,000), and everyone would walk away with $2,000 (twice what they put in). However, logic also dictates that a rational, utility-maximizing person should logically put no money into the pot, since they would get a share of everyone else's contribution and keep their own. For example, if Player A put in nothing and kept his $1,000, even if the other three only put in $100 each, Player A would end up with $1,150 ($1,000 + [$300 x 2 / 4]) while Players B, C, and D would end up with $1,050 ($900 + [$300 x 2 / 4]). The more the others put in, the more one-sided the benefit for the player that put in nothing. If each of the other three put in $500, for example, Player A would end up with $1,750 ($1,000 + [$1,500 x 2 / 4], while the other three would end up with $1,250 ($500 + [$1,500 x 2 / 4]. In short, logic should dictate that everyone walks away with the same amount (their initial amount) because they're best served by not contributing anything and hoping to benefit from the generosity of others. And yet studies repeatedly show that almost all participants put at least some amount into the pot out of a sense of obligation to the greater good, fairness, etc.

The Diner's Dilemma is a situation where a group of people go out to dinner and agree in advance to split the check equally. Logic would dictate that, between and expensive and inexpensive item, a rational, utility-maximizing person should logically order the more expensive item, since the group is splitting the cost equally. The only downside is if everyone orders the more expensive item. For example, if you go out to eat with four friends and three of them order the soup for $10 and you order the lobster for $50, you're each paying $20 for dinner ($80 / 4) and the person that ordered the lobster is paying way less than they would have on their own. In reality, most people in that situation tend to order the less expensive item so their choices don't stand out as greedy or selfish.