Peripheral Visual Information Affects Choice

Researchers have known for some time that decision makers are more likely to select items that they look at more during the choice process—and, of course, packaging and placement can encourage this. This is called "attentional choice bias," and it means that you are more inclined to choose the item you're looking at, other factors being equal. One result of attentional choice bias is that at least some of the time you may end up choosing a less desired option simply because you were paying more attention to it.

Indeed, many experiments have shown that this is the case when individuals are scanning supermarket shelves or comparing items side by side. But what happens if the item a decision maker is not focused on is removed, so that it doesn't even appear in their peripheral vision? What if, for example, a consumer is shopping online and viewing only one choice at a time?

This is the question that Caltech social science graduate student and Chen Graduate Fellow Brenden Eum, working with Stephanie Dolbier (BS '18) of UCLA and Antonio Rangel, Bing Professor of Neuroscience, Behavioral Biology, and Economics, sought to answer experimentally.

Eum, Dolbier, and Rangel recruited 50 subjects who reported a liking for snack foods. First, they were shown images of 60 different snack foods on a computer screen and asked to rate, on a five-point scale, how much they like to eat each of these particular foods. Once their preferences were measured, the subjects were asked to make choices between two items shown on the screen. Under one condition, the "visible condition," they were presented with both items on the screen, one on the left side and the other on the right. Eye-tracking software measured the participants' visual fixations as they made their choices.

Under another condition, the "hidden condition," subjects were presented with only the item they were focusing on, as registered by eye-tracking software, while the other item was removed, leaving only an empty box in its place.

Under the visible condition, the participants' choices aligned with the outcomes expected from prior studies of attentional choice bias. That is, even when a participant said they liked chocolate bars more than salty peanuts, they were more likely to choose the peanuts if they spent relatively more time looking at them.

In the hidden condition, which simulates a set-up often found in e-commerce, where one item is shown at a time, the researchers found that the same attentional choice biases were at work but that they were twice as strong as when both items were shown to decision makers.

"There are hundreds of papers about attentional choice bias," Rangel says. "We know that if you're indifferent between two things when you come into a store, you're more likely to choose an object if I can get you to pay more attention to it. This research shows that if I remove one option from your immediate visual field, you'll be twice as likely to choose the one you're looking at."

The study further recorded the duration of visual fixations. "People typically look at the options about two or three times before making a choice," Eum says. "This back-and-forth is faster when both items are visible, and slower when you can only see items one at a time." Rangel speculates that "if there's information in the periphery, the visual system pulls your attention away, making your fixation shorter. When there's nothing in the periphery to pull your attention away, you fixate longer."

"These phenomena are probably known to marketers already as tricks of the trade," Eum says. "But as neuroscientists, we are trying to understand how these techniques are grounded in the decision-making process."

This research is described in "Peripheral Visual Information Halves Attentional Choice Biases," and published in Psychological Science. Eum, Rangel, and Dolbier are co-authors. Funding was provided by the NOMIS Foundation.