Did you know that too many choices overwhelm your brain

Do you always find it difficult to decide what to order for lunch? According to researchers, this is due to the phenomenon of choice overload, which occurs as a result of too many choices being available to your brain.

A study conducted at California Institute of Technology by Colin Camerer reveals new insights into choice overload, including the parts of the brain responsible for it, and how many options the brain actually prefers when it is making a choice.

In the study, volunteers were presented with pictures of scenic landscapes that they could have printed on a piece of merchandise such as a coffee mug. Each participant was offered a variety of sets of images, containing six, 12, or 24 pictures. They were asked to make their decisions while a functional magnetic resonance imaging (fMRI) machine recorded activity in their brains. As a control, the volunteers were asked to browse the images again, but this time their image selection was made randomly by a computer.

The fMRI scans revealed brain activity in two regions while the participants were making their choices: the anterior cingulate cortex (ACC), where the potential costs and benefits of decisions are weighed, Camerer said; and the striatum, a part of the brain responsible for determining value.

Camerer and his colleagues also saw that activity in these two regions was highest in subjects who had 12 options to pick from, and lowest in those with either six or 24 items to choose from.

Camerer said that pattern of activity is probably the result of the striatum and the ACC interacting and weighing the increasing potential for reward (getting a picture they really like for their mug) against the increasing amount of work the brain will have to do to evaluate possible outcomes.

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 said.

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.

Of course, a trip to the nearest grocery store is likely to reveal that lots of products come in many more than a dozen varieties. There might be a whole aisle of toothpaste of varying brands, sizes, flavours, textures, and properties, and on the condiment aisle, there might be dozens of kinds of mustards to choose from.

Camerer said that's partly because people tend to feel freer and like they have more control over their lives when they have more options to choose from, even if having all those options ends up distressing them at decision time.

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

The study appears in the journal Nature Human Behaviour.