October 22, 2004
Coke And Pepsi Advertising Effects Measurable In Brain Scans

Samuel M. McClure, now at Princeton University, Jian Li at Baylor College of Medicine, and a number of colleagues at Baylor have found that brand preferences are measurable using functional magnetic resonance imaging (fMRI) brain scans.

The preference for Coke versus Pepsi is not only a matter for the tongue to decide, Samuel McClure and his colleagues have found. Brain scans of people tasting the soft drinks reveal that knowing which drink they're tasting affects their preference and activates memory-related brain regions that recall cultural influences. Thus, say the researchers, they have shown neurologically how a culturally based brand image influences a behavioral choice.

These choices are affected by perception, wrote the researchers, because "there are visual images and marketing messages that have insinuated themselves into the nervous systems of humans that consume the drinks."

Even though scientists have long believed that such cultural messages affect taste perception, there had been no direct neural probes to test the effect, wrote the researchers. Findings about the effects of such cultural information on the brain have important medical implications, they wrote.

Advertising may be contributing to the obesity epidemic.

"There is literally a growing crisis in obesity, type II diabetes, and all their sequelae that result directly from or are exacerbated by overconsumption of calories. It is now strongly suspected that one major culprit is sugared colas," they wrote.

My prediction: Some day people will be able to elect to be put under brain scanners and shown a series of advertising images to discover which advertisers have done the best job of programming them to like their products. Then some drug combination or other therapy will be available to deliver in conjunction with an image of some product to cause the cancellation of the neural pattern that makes one favor that product.

Besides the health implications of studying soft drink preference, the researchers decided to use Coke and Pepsi because-- even though the two drinks are nearly identical chemically and physically--people routinely strongly favor one over the other. Thus, the two soft drinks made excellent subjects for rigorous experimental studies.

In their study, the researchers first determined the Coke versus Pepsi preference of 67 volunteer subjects, both by asking them and by subjecting them to blind taste tests. They then gave the subjects sips of one drink or the other as they scanned the subjects' brains using functional magnetic resonance imaging (fMRI). In this widely used imaging technique, harmless magnetic fields and radio signals are used to measure blood flow in regions of the brain, with such flow indicating brain activity levels. In the experiments, the sips were preceded by either "anonymous" cues of flashes of light or pictures of a Coke or Pepsi can.

The experimental design enabled the researchers to discover the specific brain regions activated when the subjects used only taste information versus when they also had brand identification. While the researchers found no influence of brand knowledge for Pepsi, they found a dramatic effect of the Coke label on behavioral preference. The brand knowledge of Coke both influenced their preference and activated brain areas including the "dorsolateral prefrontal cortex" and the hippocampus. Both of these areas are implicated in modifying behavior based on emotion and affect. In particular, wrote the researchers, their findings suggest "that the hippocampus may participate in recalling cultural information that biases preference judgments."

The researchers concluded that their findings indicate that two separate brain systems--one involving taste and one recalling cultural influence--in the prefrontal cortex interact to determine preferences.

The ventromedial prefrontal cortex gets programmed by advertising.

We delivered Coke and Pepsi to human subjects in behavioral taste tests and also in passive experiments carried out during functional magnetic resonance imaging (fMRI). Two conditions were examined: (1) anonymous delivery of Coke and Pepsi and (2) brand-cued delivery of Coke and Pepsi. For the anonymous task, we report a consistent neural response in the ventromedial prefrontal cortex that correlated with subjects' behavioral preferences for these beverages. In the brand-cued experiment, brand knowledge for one of the drinks had a dramatic influence on expressed behavioral preferences and on the measured brain responses.

They found that the knowledge of the Coke brand exerted a more powerful effect upon the brain than knowledge of the Pepsi brand. Given that Coke is the bigger seller what is to be expected. Dr. Read Montague, director of the Brown Human Neuroimaging Lab at Baylor, said the brain scans allowed him to predict preference before a sip was taken.

Functional magnetic resonance imaging allowed Montague to predict fairly accurately which people preferred Coke or Pepsi before they even took a sip.

We were stunned by how easy this was, Montague said. I could tell what they were going to do by looking at their brain scans.

A large portion of the market value of Coca Cola is the result of patterns of neural network connections which Coke advertising has created in hundreds of millions of people.

Surely there are similar neural phenomena causing national loyalties, religious loyalties, and other preferences.

Share |      Randall Parker, 2004 October 22 04:04 PM  Brain Conditioning

Alexander Williams said at October 22, 2004 4:52 PM:

I think these guys shoot themselves in the foot early on. Coke and Pepsi may taste similar (in the sense that they're both cola drinks), but they are vastly different in actual flavour.

Randall Parker said at October 22, 2004 6:25 PM:


The scientists tested preferences when people knew and didn't know what brand they were drinking. The scientists also watched brain scans under each circumstance. They got very different results in both voiced preferences and in brain scans when the users did and did not know what they were drinking.

Jody said at October 23, 2004 9:26 AM:

I would like to see the brain scans for those drinking the original (1880s) Coca Cola. I bet brain scans would've been just a leeettle different.

Also I wonder if the original Coca Cola was obesity neutral. How much cocaine would it take to offset the sugar in a can of Coke. Inquiring minds need to know!

p said at October 23, 2004 4:38 PM:

Let's stick with the facts ... there is no obesity epidemic (this is pure hype) ... there is a great deal of research on Adv (this is not the first research on the topic)and it has limited impact on humanoids ... we have known for years that brain activity occurs in specific regions ... this research has just used a branded product ... the speculation is well out of the validity region ... Is this a science digest or a science fiction primer?

Randall Parker said at October 23, 2004 5:38 PM:

P. Yes there is a real obesity epidemic. No, it is not pure hype. Growth in per capita soft drink consumption is contributing to the problem. The epidemic is hitting all age groups.

The rise in the rate of obesity is causing rises in rates of other disorders. Most notably, Type 2 insulin resistant diabetes is a greater risk as excess fat levels increase and type 2 diabetes incidence is rising.

BOSTON As reported yesterday by the Centers for Disease Control and Prevention, an estimated 129.6 million Americans, or 64 percent of the population, are overweight or obese. As obesity in America has become an epidemic over the past decade, the rate of type 2 diabetes, which is closely linked to obesity, has skyrocketed. It is estimated that 18.2 million people in the U.S. have diabetes, and over 90 percent of those have type 2 diabetes. Furthermore, the percentage of adults with diabetes increased 65 percent from 1990 to 2001.

"Statistically, adults in the U.S. have gained 2 billion pounds over the past decade, which is an average of one pound per year per person. This is true for both men and women," says C. Ronald Kahn, M.D., President and Director, Joslin Diabetes Center. "For every one pound increase in weight, there is a 3 to 4 percent increase in the prevalence of type 2 diabetes, or about 800,000 new cases. We urge individual Americans to take steps to reduce their own risk of diabetes, but I also believe prevention must be a priority for the healthcare industry, the food industry and the government."

Research on advertising: You mean if, say, Coke cancelled all their advertising then Pepsi wouldn't gain market share? Or if Ford cancelled all their adverts that GM, Toyota, and Chrysler wouldn't gain marketshare?

p said at October 24, 2004 1:40 PM:

Randall, I stand by the term hype. The studies that are often quoted (and the one you note) are epidemiological studies that are not theory testing rather data fishing exercises. The correlation identified by these researchers is real; it is the significance of the finding is suspect. The number of intervening factors between soft drink consumption and obesity are larger than the concept of obesity itself. The fact that two variables, time and soft drink consumption, increased as obesity increased suggests the possibility of a spurious correlation. Without seeing all the variables that the researchers found that were similarly correlated I remain skeptical what we can safely infer as scientists (If for no other reason than context provides perspective. Journalists and masters of hyperbole may wish to infer a great deal more.

I have a problem with researchers who practice data fishing as a science. I find the practice ascientific given that it is non-falsifiable in its design (one generates a plausible explanation and the work is done. Real science is based upon building non-falsifiable theories that are tested in a manner that competing explanations can arise and be rejected). Once we can demonstrate the finding in an experimental setting and rule out alterative explanations we are ready to call it a scientific findings. Right now this finding is a weak hypothesis. Lets rule out all the other things that are also correlated with Obesity.

Advertising research investigates the persuasive nature of advertising as well as the manner in which it interacts with consumer attitudes and behaviors. In addition, it explores the role it plays in consumer cognitive formation.

Randall Parker said at October 24, 2004 3:06 PM:

P, You applied the term "hype" to the idea that there is an obesity epidemic in the first place. That is the chief question. Whether soft drinks are contributing to that epidemic only matters if there actually is an epidemic. Well, do you still stand by your contention that there is no obesity epidemic?

It is a finding that obesity is increasing. You seem now to be implicitly accepting that this is really the case.

It is a finding that per capita soft drink consumption is also increasing. You could argue that the soft drink calories are displacing, say, milk calories. But the increase in soft drink consumption strikes me as too large to be only having a calorie source displacement effect.

You didn't answer my question about whether companies would suffer no loss of sales if they cut back on their adverts.

p said at October 24, 2004 7:37 PM:


Obesity is increasing ... this does not constitute an epidemic ... just an increase ...

The current definition of obesity by BMI is troubling given that there is no basis for the new standards ... The new BMI standards classify too many people as obese regardless of longevity ... Numerous researchers have pointed this out.

As for the causal link not demonstrated. Just one of probably many correlations.

As to your question on whether companies would suffer loss I missed it - sorry. Good question ... I think that it depends. If we look at the Philip Morris and company I would say no. Soft drinks benefit from advertising but I this would be more around brand choice rather than demand.

aj said at November 11, 2004 8:34 AM:

i love your soda it is great i enjoy the taste of wild cherry pepsi it rocks hader than any other soda i have taste the pepsi blue was good too. i really liked that to . i use that drink before every basket ball game i play and after we play. cause it quenches my thirst.

C said at December 17, 2004 3:48 PM:

Has anyone considered the fact that 1: pepsi is more carbinated then coke and 2: the reasons peoples brainwaves engaged with the coke vs pepsi 'name' could be simply that they associated it automatically with 'cocaine'? That would explain No activity with the pepsi name but drastict activity with the 'coke' name. Everyone knows that 'coke' used to use cocaine. If you look at it from a viewpoint other then just brand preference and ask why, that brand preference? it might just help. I know, to simple and elementary, right?

Andrew said at January 27, 2005 6:45 PM:

ppl...really...you have to like Coke it is the best drink ever invented. Drink it!..if you like Pepsi you are my enemy!!!!!!!!:@:@:@:@:@

eboigbe osezua said at March 31, 2005 2:57 AM:

i have seeing this fact coming in the future a time will come when coke will no longer be good to comzum. i have see it . it effect on the brain. keep yr eye's out yr ear's out too. 4 more imformation

Lamar Cole said at September 27, 2005 11:43 AM:

Love is two people sipping Coca Cola from the same straw on a warm sunny day.

Alexandra Blazer said at November 29, 2005 6:06 PM:

Well I personnaly think that coke is better it jas more taste and umm I prefer drinking it w/ a meal. I also have a question to ask. Umm How does coke or pepsi affect the thought in the brain after consuming one or the other?

Coca said at February 1, 2006 1:03 AM:

Seem like a long while ago people we're commenting this but I've got a little question I'm going to throw out there anyway.
How could he predict wich soda they would prefer with the help of brain wawes?

It doesn't say how he used the brain scans, maybe this is some obvious fact but I do not understand.

ankita dhingra said at October 14, 2006 4:22 AM:

we the students of eco hons 1st yr are doing a project on sales promotion.in this project we have emphasised on how advertising and media effect the mindset of the people regarding a specific product.thus we would be highly elited if you could help us in the sense by providing some case study differenciating any two or three products,with references,graphs,pie charts,figures etc showing how have they effected the pattern of sales.kindly reply at the earliest.
thanking you

tom said at January 3, 2007 10:21 AM:

coke is so much better than pepsi. pepsi stole their idea and managed to be popular. coke could have bought out pepsi bit they were nice and let them try to make i big company. however they managed but coke was made before pepsi proving that they stole their idea.

mirza said at December 3, 2007 4:41 AM:

i would give my everything to taste one drop of coke from 1890's.. guys come on whats wrong with it? its just coke, doesnt beat..

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