A Classic Neuromarketing Experiment

Cola in a glass

A Classic Neuromarketing Experiment

In 2004, researchers at Baylor College recruited 67 people. They took them into the biomedical laboratory and divided them into four groups. All groups were asked the same question about two almost identical cultural products.

Stated Preference

The question they were asked was, “Which drink do you prefer to consume: Coke, Pepsi or no preference?”

The results were almost evenly divided between Coke and Pepsi. People had a strong preference for either one or the other.

Behavioural Preference (Taste Tests)

Groups 1 & 2 – Anonymous

Next, the first two groups were given two identical plastic cups. Cup A. Cup B. One of them contained Coke. One of them contained Pepsi. Both were unmarked, just a generic styrofoam white cup.

Predictably, the subjects were asked to taste them both and decide whether they preferred cup A or cup B.

The results were evenly split, just like the stated preference question. About half preferred cup A. Half preferred cup B. No significant difference.

Group 3 – Pepsi

Group 3 was also given two identical cups but this time one of them was marked Pepsi. The other was unmarked. Subjects were told that it contained either Coke or Pepsi. In fact, it contained Pepsi as well.

The result was split. The presence of a Pepsi label did not significantly change the result any more than the anonymous taste test.

Group 4 – Coca-Cola

Group 4 was given two identical cups. This time, one was marked Coca-Cola. The other was unmarked. Subjects were told that it could contain either Coke or Pepsi. In fact, it contained Coca-Cola.

This time the results significantly differed to the anonymous taste test. Compared to the anonymous groups, these subjects showed a strong bias in favour of the labelled cup.

The Anonymous MRI Scan

Next, the subjects underwent a functional Magnetic Image Resonance scan. If you’ve ever had an MRI scan, you’ll know that an MRI machine is a claustrophobia cylinder that you get rolled into. You can’t exactly move around inside that machine. You certainly can’t lift your head to sip on a white styrofoam cup.

To deal with the physical constraints, a small plastic tube was inserted into each subject’s mouth. The tube injected a small quantity of either Pepsi or Coke. It was an amount large enough to fully taste, but small enough to be swallowed comfortably with little movement.

To give the subjects a few seconds warning before the liquid was squirted into their mouth, a system of timed, yellow flashing lights was devised. Each time the drink was about to be squirted, whether it was a squirt of Coca-Cola or a squirt of Pepsi, the same generic yellow flashing lights would appear and do a pulsing countdown. No brand information was given. Subjects said nothing and did nothing except enjoy their anonymous drink delivery. The scanner took pictures of their brain activity.

The results of the brain scans showed the brain responses in the ventromedial prefrontal cortex (the ‘reward centre’ of the brain) scaled with the same as the behavioural taste test. For this anonymous unbranded drink delivery group, the brain signals were all pretty consistent.

Pepsi Group MRI

Then, Group 3 went into the scanner. This time, instead of having a yellow flashing light to cue the squirt of drink, they sometimes saw a can of Pepsi flash the drink delivery cue.

The result was that the ventromedial prefrontal cortex showed no significant difference in activity when the can of Pepsi flashed and when the yellow flashing light cued the squirt.

Coca-Cola Group MRI

Group 4 hit the scanners. This time, to cue the squirt of a drink, either a generic yellow light flashed or a can of Coca-Cola flashed. Every element of this tightly controlled experiment was identical to the Pepsi group, but the flashing Pepsi cue was replaced with the Coke can and, of course, the drink was also different.

The process, timing and drink delivery were exactly the same as the Pepsi group and exactly the same as the anonymous group, but the brain activity was very different. When the machine flashed the can of Coke, the knowledge of the brand invoked much stronger brain responses than when the generic light flashed. The reward-centre of the brain lit up in multiple places with the flashing Coke can, but not after the generic yellow cue, despite it being the same drink.

The flashing in fact triggered activity in the hippocampus and midbrain.

An Insinuating Conclusion

The conclusion drawn was that cultural knowledge (e.g. brand knowledge) insinuates itself into the nervous system, biases preference decisions, and has a physiological effect.

And while most people think Coke and Pepsi are pretty evenly matched, Pepsi has none of the brand power that Coke has. This was already demonstrated decades earlier when taste tests showed that people preferred the taste of Pepsi, but bought Coke.

Most people think that brands are intangible so they aren’t real. They don’t matter. They’re a figment of corporate imagination and nothing more than a logo. Neuromarketing studies like the one just mentioned show that brands have a powerful influence on people’s behaviour, thinking and feeling – despite all logic.

Don’t even get me started on the study of a placebo tablet (a mixture of oil and water) that was labelled ‘Rogaine’ and resulted in subjects experiencing 60% hair regrowth.


Samuel M. McClure; Jian Li; Damon Tomlin; Kim S. Cypert; Latane M. Montague & P. Read Montague: Department of Neuroscience, Menninger Department of Psychiatry and Behavioural Sciences, Baylor College of Medicine.

“Neural Correlates of Behaviour Preference for Culturally Familiar Drinks.” Published in Neuron, October 14, 2004, Vol 44, page 379-387.