HoustonChronicle.com - Coke or Pepsi? It may not be up to taste buds

Most people have a preference for Coke or Pepsi. What most people may not realize, however, is that this preference is dictated by image rather than taste. At least that's the conclusion of a neuroscientist at Baylor College of Medicine.

In one experiment, a group of people were given one cup that was labeled Coke (it was) and another unlabeled cup. The participants were told there was either Coke or Pepsi in the second cup (all were filled with Coke). Nearly 85 percent of participants said the cup labeled "Coke" tasted better.

In the same experiment, only with Pepsi labels and Pepsi in the two cups, there was no behavioral effect. Half of the participants said the Pepsi-labeled product tasted better and half preferred the unlabeled one.

Later, participants were given two unlabeled cups, one with Pepsi and one with Coke. There was no preference — half liked Coke, half liked Pepsi.

The scientist who led the experiments, Read Montague, said the Coke label clearly has a powerful impact on the brain.

"It suggests that the message may be very powerful in some instances, and it may be completely ineffective in the case of others," said Montague, director of the Brown Human Neuroimaging Laboratory at Baylor.

Montague's lab studies neural reward processing — stimulants such as sugar and caffeine enhance dopamine, a sort of reward for the brain for ingesting foods like sugary beverages. Since Coke and Pepsi both contain these ingredients, taste the same and look the same, Montague was curious about what happens in the brain to produce a preference.

The neural response was surprising, he said. By looking at magnetic resonance imaging scans of the brain it was possible to predict whether a participant would prefer Coke or Pepsi.

The results suggest humans are unique in allowing cultural messages to override their biological instincts.

A dog, for example, will eat almost any food put into its bowl — or inadvertently left on the counter. A human, however, might pass on a cookie or slice of cake if they imagine that this food would add to a waistline. In the same way, a person might prefer Coke over Pepsi when, biologically, there is no difference in how it affects them.

If cultural messages or beliefs become strong enough, Montague said, they can override facts or data. The implications are important in a world where many movements are driven by ideals not entirely based in reality.

"People will blow themselves up for an idea or belief even when the most of us think there is no payback," he said.

Montague said his lab is not trying to help companies better market themselves to consumers. He actually hopes his work will make people more aware of their susceptibility to sophisticated marketing. He also says the work has implications for addiction.

"We want to be able to better understand how brains work so that we can hopefully cure more neurological disorders," he said.

Coke or Pepsi? It may not be up to taste buds

Scientist finds image may have final say in choice