Most people are familiar with the way committees make decisions about budgets. A group of individuals, each with their own priorities and interests, must work together to decide how to divide up resources. These decisions are usually guided by rules, like requiring a majority vote or unanimous agreement.
Economists have long studied how people behave in these situations and which decision-making rules work best. Marina Agranov, a professor of economics at Caltech, tests these theories in a recent study. “I want to know whether these theories hold up in the real world and how they might need to change to better predict human behavior,” she says.
An unfair reputation
One common rule, unanimity, often gets a bad rap. “Under unanimity, everyone has veto power, so just one person can block a proposal,” Agranov explains. “Even reasonable and fair proposals can fail because of personal grievances or group dynamics. Majority rule is usually more practical and leads to faster decisions.”
But things get more complicated when the budget isn’t fixed—when, for example, it might grow in the future. Here, unanimity can have surprising benefits. “With majority rule, people often rush to approve smaller budgets, worried they’ll be left out of future deals,” says Agranov. “This can lead to bad outcomes. Unanimity, by forcing everyone to agree, encourages waiting. Committees are more likely to hold out for a bigger budget, which benefits everyone.”
To test this, Agranov and her team created experiments in a lab. “The lab gives us control,” she says. “We can set the rules, track the budgets, and watch how people negotiate. If a theory doesn’t work in this simple setting, it’s unlikely to work in the real world.”
Making a decision
In these experiments, 288 participants were split into small groups and tasked with dividing budgets. Each person sat at their own computer and communicated with teammates through a chat system. Every round, a randomly chosen member could propose how to divide the budget or delay making a decision. Proposals required either majority approval (two out of three votes) or unanimous agreement.
If the group didn’t reach a deal, there was a 20% chance the round would end, and no one would get anything. This reflected the idea that people value immediate rewards more than uncertain future ones.
The experiments started with a budget of $24. In some scenarios, the budget could grow to $48 or $96 in later rounds, depending on chance. In others, it stayed fixed at $24. These setups mimicked real-world committees that meet repeatedly over time.
Clear winner
The results were clear. While unanimity slowed decision-making in one-off scenarios, it worked well in ongoing groups. When future budgets were uncertain, unanimity encouraged patience and fairness, leading to better outcomes.
For example, with $24 to split, the fairest division is $8 per person. But under majority rule, two members might team up to take a larger share. With uncertainty about the future, however, people were more likely to make fair offers. “If you exclude someone now, they might retaliate later,” Agranov explains. “Being fair today makes it more likely you’ll benefit tomorrow.”
In the end, Agranov’s findings highlight the trade-offs between speed and fairness. While unanimity can be frustrating, it pushes committees to cooperate and wait for bigger rewards. In many cases, that patience pays off.
