The Coke/Pepsi brain scan and other cool experiments at Human Neuroimaging Lab

The Human Neuroimaging Laboratory at Baylor College of Medicine performs groundbreaking research using fMRI scanners (see our main story on the lab's one-man IT staff). Here's a look at some of the lab's major experiments conducted since it opened in 2003.

Hyperscanning

HNL developed this unique research method, which lets multiple human subjects interact with each other while their brains are scanned simultaneously in separate fMRI machines. Hyperscanning software lets scientists control multiple brain scanners over the Internet, even if they are separated in distance by thousands of miles. Subjects in the United States and Hong Kong have been studied simultaneously using this method.

Trust and reputation: the money game

Using hyperscanning, a person in one scanner at Baylor College plays several rounds of a trust game with another person at the California Institute of Technology. Each person gets multiple turns as an investor and multiple turns as a trustee.
The investor starts out with $20 and can either keep money or give it to the trustee, knowing the portion given to the trustee will triple in value. When the trustee becomes investor, he or she can either reciprocate that good will or horde the newfound riches, turning it into an unfair exchange.

"Where it gets interesting is seeing how the trustee divvies up the profit and how that encourages — or discourages — the investor from placing more money in the next round," HNL director Read Montague explained in a news report. "If it's divided 50-50, the next time the investor might decide to invest more. If the trustee keeps it all, then in the next round the investor might not give up even $1." The experiment shows how activity in the brain's caudate nucleus region reflects a person's intention to trust someone. As the game progresses, the "intention to trust" signal starts appearing sooner as reputations for generosity are bolstered – assuming the players are fair to each other.

The Coke-Pepsi test

In what was formally known as the culture and preferences experiment, the HNL examined the tendency of people to express strong preferences for either Coke or Pepsi, even though they are nearly identical in chemical composition. Subjects' brains were scanned while either Coke or Pepsi was squirted into their mouths. In some cases, the subjects knew which drink they were receiving and in others it was a mystery.

Soda consumers showed no preference when they didn't know what they were getting. Yet when they were shown company logos, three out of four people said they preferred Coke.

Brain scans showed that seeing the Coke label stimulated parts of the brain that were unaffected by Pepsi's logo. Specifically, the famous Coke brand "stimulated a huge increase in activity in parts of the brain associated with cultural knowledge, memory and self-image," one newspaper reported. The brain scans thus showed vividly the impact a marketing campaign can have on the human brain, and that people routinely make decisions based not on the taste of a product but on brand preference