What You See Affects What You Want

When it comes to making choices, say Caltech's Antonio Rangel and his colleagues, much depends on which items catch—and keep—your eye.

"We're interested in how the brain makes simple choices, like which item to pick from a buffet table," says Rangel, professor of neuroscience and economics. "Why is it that when we look at the buffet table, our gaze shifts back and forth between the items in order to make a choice? What is the role of visual attention in all this?"

To find out, Rangel—along with Caltech postdoctoral scholar Ian Krajbich and Stanford University's Carrie Armel—designed a mathematical model to describe the impact of what they call "visual fixation" on the making of these sorts of choices. (Simply put, visual fixation is the amount of time you spend gazing in one direction or at one item versus another.) They recently published their research online in the journal Nature Neuroscience.

"The model makes very specific predictions about how the pattern of fixation is related to our choices," Rangel explains. "For example, after controlling for other variables, items that are looked at more should be chosen more often."

But are they? To make sure, the team carried out an eye-tracking experiment in which subjects were shown pairs of food items on a computer screen, allowed to look at the items for as long as they wanted, and then were asked to choose one or the other. While the subjects gazed, the researchers tracked the movements of their eyes.

Just as predicted, the item a subject looked at longest was the one he or she most often picked—nearly three-quarters of the time, in fact.

Interesting stuff on its own merit, right? It also has implications for the business world—putting increased emphasis on things like packaging and in-store displays. "[T]he model explains how cultural norms (for example, reading left to right) can interact with comparator processes to produce cultural choice biases," the scientists write. "These biases help to explain, for example, why shelf and computer screen space on the top-left is more valuable than other positions."