When deciding between two similarly appealing options, people tend to prefer the one that they spend more time looking at. The results, published online this week in Nature Neuroscience, suggest that the subjective value of an item can be enhanced simply by looking at it for longer.

In order to choose what they prefer, people often look repeatedly back and forth between options, presumably as a way of comparing the two alternatives. Rangel and colleagues asked hungry participants to choose between pairs of appetizing snack foods that the participant had previously claimed to like equally. The participants were allowed to view both items until they selected the one they preferred. The authors found that participants chose the option they looked at half a second longer about 70% of the time.