We know not to judge a book by its cover—but new research shows that may be exactly what we do.

Scientists have discovered that novel objects perk up the reward system of our brains, indicating our sense of adventure—exploring or learning something new—may be just as tempting as cash and other prizes in the choices we make. Researchers say the finding may explain why marketers are able to bolster sagging sales by simply repackaging old products.

Brain processes "might encourage you to sample [products previously dismissed] again—even though it doesn't make much sense," says Bianca Wittmann, a neuroscientist at University College London's Institute of Cognitive Neuroscience and co-author of the study published today in the journal Neuron. "Just because it has new packaging doesn't mean it has gotten much better."

But Baba Shiv, a professor of marketing at Stanford University's Graduate School of Business, warns marketers to beware of trying to dupe consumers. Although novelty may temporarily boost sales, he says, they will likely slump again once customers realize nothing but the packaging has changed.

Wittmann and her colleagues scanned the brains of 20 volunteers while they played a game in which the goal was to accumulate money. In each trial the researchers showed players four pictures, one of which, if chosen, would net a cash payoff. The images were taken from a bank of 20 postcards, each featuring a different mountain scene. As the game went on, participants learned which images had the highest value.

When subjects selected a postcard that they knew was valuable, a region in their forebrain called the striatum (known to process rewards and pleasures) activated in expectation of their cash prize.

After the game had gone on for awhile, researchers inserted new images of similar landscapes into the mix. They noticed that in nearly all cases, players opted for the fresh shots over the old ones, including the known moneymakers.

"Participants seem to treat the novel ones in a special way," Wittmann says. "Participants treat these novel stimuli as if they expect a higher reward from them."