Coke wins the Pepsi challenge

Here's a story that probably was front-page news in Atlanta a few months ago, but which SC only found out about from next month's Stereophile (as often is the case with such things, it arrived halfway through the "previous" month). The audio hook is completely self-serving and unobvious; more interesting is the actual science, in particular for what it says about the ability of certain words to take on a very real power over your thinking.

The article by Samuel McClure and colleagues, which originally appeared in the October 14 issue of Neuron, is titled "Neural Correlates of Behavioral Preference for Culturally Familiar Drinks". Despite the imposing name, it's basically the Pepsi Challenge carried out (in part) inside an fMRI machine.

The methodology is quite interesting, if only because of the difficulties involved with getting people to drink inside an fMRI tube without drowning them. This was accomplished like so (although we're getting ahead of ourselves):

Individual squirts of Coke and Pepsi (0.8 mL each) were delivered to subjects through cooled plastic tubes held in the subjects’ mouths with plastic mouthpieces. The volume of soda delivered on each squirt was sufficient to allow the subjects to fully taste the soda but were small enough to allow them to easily swallow while lying in the scanner. A computer-controlled syringe pump (Harvard Apparatus, Holliston, MA) allowed for precise delivery of the colas.

Of course, it's not merely enough to know what's going on inside people's brains when they drink a soda; you have to know whether or not they have an opinion about what they're drinking, and whether or not they can actually tell the difference. The former tells you if they think drinking the soda is a pleasurable experience, the latter if they actually can tell, or if the observed reaction is due to something other than the chemical composition of the soda.

Unsurprisingly for anyone who thinks that all colas are just "brown, carbonated sugar water" (McClure et al.'s description), there was no statistically significant correlation between stated and "behavioral" preferences -- in other words, when they actually did carry out the Pepsi Challenge, they found that people who said they liked Coke better couldn't actually tell between unlabeled drinks. It's not really true that this is the case for everyone; McClure et al. don't mention whether or not they threw out subjects who could actually discriminate above chance, or if they even had any in their sample. SC knows such people exist, though -- he is one. The point here is to measure the suggestive power of branding, and so it's probably most helpful to stick to that part of the population (a rather large majority) that really can't tell the difference.

An interesting variation of the Pepsi Challenge (not carried out inside the fMRI machine) involved having subjects drink from one labeled cup and one unlabeled cup. When the label was "Coke", subjects showed a strong preference for the labeled cup, but when the label was "Pepsi", the distribution of preferences was notably more random. They don't mention whether or not people who expressed preferences for one label or the other actually gravitated towards their stated choices when available; it would be rather strange if they didn't, unless they suspected that the labels might be deceptive. In fact, they were not; in the "semianonymous" trials, both cups contained the same soda.

But the really interesting result came from the fMRI tests -- when subjects were given Coke through the tube/syringe contraption mentioned above, they showed meaningful brain activation in 6 areas, when told it was Coke. No such reaction occurred with Pepsi. No deception was involved in this experiment -- it was a straightforward test of labeled vs. unlabled Coke, and labeled vs. unlabeled Pepsi.

Observing that significant cultural meaning is attached to both Coke and Pepsi, McClure et al. conclude that it's this specific information which acts to bias people's preferences, since it seems able to override preferences in the absence of any such information. From a linguistic standpoint, it's hard to argue with that conclusion -- clearly, the label "Coke" has power over people's minds in ways that "Pepsi" does not -- but it's not clear that it's the whole story, either. Admittedly, Coke is associated with a long history of cultural significance, and much memorable marketing, but they hardly have a monopoly in this regard. The word "enjoy" might trigger strong Coke associations, but SC would bet any reader who remembers the '80s and '90s can easily recall which soda is associated with the lines "The choice of a new generation" or "You got the right one, baby (uh-huh!)". It simply doesn't make sense to SC that the Coke label should be the beneficiary of cultural knowledge while Pepsi is not -- they've both been out there advertising heavily for a long time. Your host isn't familiar with psychological literature on advertising, but the necessary follow-up question is: "To what extent do the various slogans and jingles actually imprint themselves as associations with lexical items?". If Coke advertising historically has stuck with people, while Pepsi has not, this would be strong confirmation of McClure et al.'s conclusion, which otherwise remains rather speculative.

As for the audio conclusion mentioned at the outset? Well, nobody has ever successfully demonstrated an ability to distinguish between well-designed amplifiers in double-blind tests (there are caveats here about distortion levels and output impedance, but they're not relevant for this purpose). Suffice it to say that the Stereophile crowd is well aware that their editorial claims don't generally hold up under double-blind -- or even single-blind -- scrutiny. So when they brought up this study, it was to suggest that brand awareness produces increased listening enjoyment. This means it's critical to know that you're sitting in front of a pair of $350,000 Wavac amplifiers instead of a $200 Pioneer receiver. Such a claim could never be tested, because an MRI machine provides a really awful acoustic environment. But it does provide an amazingly useful justification for the continued existence of magazines which exist to create exactly the sort of brand awareness without which that receiver isn't worth much less than the super-amp.

Comments

[*RURU*]

i think that pepsi is better then coke because it is and thats all i have to say period.

[*RURU*]

i like pepsi go pepsi go pepsi go pepsi

[Jonathan]

Coca-Cola was the first and will forever be the best cola. Pepsi just sounds and looks trashy, not to mention it has been a knock-off of Coke from day one. Coke is it!!!!!

[SFgiants]

Coke is far better than pepsi. pepsi is too sweet and they fail when trying to copy coke in EVERY product they make. Coke makes vanilla coke, then comes pepsi vanilla. coke makes cherry coke, then wild cherry pepsi comes out. There is obviously zero creativity over at the pepsi company. Coke has always been the classiest, whereas pepsi, as Jonathan pointed out, is totally trashy.

[ashlynn]

i am doing a report on the coke and pepsi challenge and i think pepsi i like pepsi because i think it taste better and it is sweeter and not so fizzy but everyone has a different opinion so i am not sure but coke is ok i guess

[mike]

for those who said pepsi ripped off of coke, if u go to pepsi.com, drop down menu of ads & more, pepsi legacy, page 90 of 15, coke tried to rip off of pepsi. AND THEY GOY CAUGHT! haha.

[russische frauen]

Coke is far better than pepsi. pepsi is too sweet and they fail when trying to copy coke in EVERY product they make.

[online auctions]

These two never stopped on competing one another. Even on commercials.

[squirrel]

I LOVE SQUIRRELS!!!!!!!!!!!!!! pull dat pussy

[xl pharmacy]

well you have to take into account the different markets in differents part of the world, for example in America of course Coca Cola wins, but in Asia Pepsi rules.

[Redwing Work Boots]

well this blog is great i love reading your articles.