Official: Coke takes over parts of the brain that Pepsi can't reach

The mind-altering power of advertising has been demonstrated in a remarkable study of the way in which brand recognition affects the workings of the human brain.

A well-known label is so influential, say researchers, that it can alter consumers' perception of the product's taste. They believe the findings are particularly important given the role that sugared soft drinks have on the epidemic of childhood obesity and type 2 diabetes.

The experiment, a laboratory-controlled version of the famous Pepsi Challenge, revealed that flavour seems to be the last thing that consumers rely on in their preference for Pepsi or Coca-Cola.

When asked to taste blind, they showed no preference. However, when the participants were shown company logos before they drank, the Coke label, the more famous of the two, had a dramatic impact: three-quarters of the tasters declared they preferred Coke.

At the same time the researchers found that the Coke label stimulated a huge increase in activity in parts of the brain associated with cultural knowledge, memory and self-image - so much that the scientists could use brain scans to predict which soft drink an individual was likely to prefer. The Pepsi label produced no such increase.

It is believed to be the first time that brand marketing has been shown to have a direct effect on the brain's capacity to make a choice.

Although the finding seems calculated to delight the marketing industry, it suggests that a handful of iconic brands have a particular hold on the public mind. Coca-Cola is so firmly established that it changed our perception of Christmas by persuading us that Santa Claus wears red. This "tradition" is believed to be largely the result of decades of December advertising in which Santa sported the company's corporate colour.

The findings suggest there is no scientific basis for claims made during the Pepsi ad campaign in which testers purportedly chose Pepsi over Coke when they were not told what they were drinking. "We initially measured these behavioural preferences by administering double-blind taste tests," the researchers say in their study, published in the current issue of the journal Neuron. "We found that subjects split equally in their preference for Coke and Pepsi in the absence of brand information."

The scientists chose Pepsi and Coke because the two drinks are almost indistinguishable in colour and taste yet many people express a definite preference for one or the other soft drink. "Everybody's heard of Coke and Pepsi. They have messages and, in the case of Coke, those message have insinuated themselves in our nervous system," Dr P Read Montague, director of the Brown Human Neuroimaging Laboratory at Baylor College in Houston, Texas, said. "There's a huge effect of the Coke label on brain activity related to the control of actions, the dredging up of memories and self-image. There is a response in the brain which leads to a behavioural effect."

Simply looking at a person's brain scan, the scientists were able to predict which soft drink the individual concerned was likely to prefer. "We were stunned by how easy this was," Dr Montague said. The ventral putamen, which is involved in reward-related learning, was active when people drink Coke or Pepsi. This is expected as the brain treats the pleasant taste of sugared water as a reward.

However, the scans also showed that the hippocampus and dorsolateral prefrontal cortex, areas of the brain involved in recalling emotions and cultural memories, were involved when the volunteers were exposed to the Coke brand. The Pepsi brand, meanwhile, had virtually no effect.

Dr Montague said that the work can help to understand why people form eating or drinking habits that may not be good for their health.

"We are not trying to figure out how to market something better. We want to be able to better understand how brains work so that we can cure more neurological disorders."