Scientists Uncover Why You Can’t Decide What to Order for Lunch

Researchers explore the choice overload effect, a phenomenon that hampers the brain’s ability to make a decision when there are too many options. A study conducted in California nearly 20 years ago is illustrative of the effect. In that study, researchers set up a table offering different samples of jams in a grocery store.

They alternated by providing 24 jam samples one day; another day, only six. Although shoppers were more likely to stop and try the samples when the table had 24 jams, they were also less likely to purchase any jam. Shoppers were less likely to stop at the table when it only had six jams, but when they did, they were 10 times more likely to purchase a jam than the customers at the fuller table.

Lunch entrees and fruit preserves might seem trivial, but choice overload can sometimes have serious consequences, says Colin Camerer, Caltech’s Robert Kirby Professor of Behavioural Economics and the T&C Chen Centre for Social and Decision Neuroscience Leadership Chair. As an example, he points to Sweden’s partial privatization of its social security system. The government allowed citizens to move some of their retirement savings into private funds. The government gave them hundreds of funds from which to choose, and conducted a large advertising campaign encouraging them to make their own choice.

At first, nearly 70% of the eligible adult population took an active role in choosing a fund, but the percentage quickly dropped off. After 10 years, only about 1% of newly eligible Swedes were making an active decision about where to put their retirement money.





As the number of options increases, the potential reward increases, but then begins to level off due to diminishing returns. “The idea is that the best out of 12 is probably rather good, while the jump to the best out of 24 is not a big improvement,” Camerer says. At the same time, the amount of effort required to evaluate the options increases. Together, mental effort and the potential reward result in a sweet spot where the reward isn’t too low and the effort isn’t too high. This pattern was not seen when the subjects merely browsed the images because there was no potential for reward, and thus less effort was required when evaluating the options.

Camerer points out that 12 isn’t some magic number for human decision-making, but rather an artefact of the experimental design. He estimates that the ideal number of options for a person is probably somewhere between 8 and 15, depending on the perceived reward, the difficulty of evaluating the options, and the person’s individual characteristics.




“Essentially, our eyes are bigger than our stomachs,” he says. “When we think about how many choices we want, we may not be mentally representing the frustrations of making the decision.”


“What is mental effort? What does thinking cost? It’s poorly understood,” he says.