Here’s my latest column for The Guardian, which appears in this morning’s edition:

Neuroscience and marketing had a love child a few years back. It’s name – big surprise – is neuromarketing, and the ugly little fellow is growing up.

Corporate pitchmen have always wanted to get inside our skulls. The more accurately they can predict how we’ll react to stimuli in the marketplace, from prices to packages to advertisements, the more money they can pull from our pockets and transfer into the coffers of their employers.

But picking the brains of consumers hasn’t been easy. Marketers have had to rely on indirect methods to read our thoughts and feelings. They’ve watched what we do in stores or tracked how purchases rise or fall in response to promotional campaigns or changes in pricing. And they’ve carried out endless surveys and focus groups, asking us what we buy and why.

The results have been mixed at best. People, for one thing, don’t always know what they’re thinking, and even when they do, they’re not always honest in reporting it. Traditional market research is fraught with bias and imprecision, which forces companies to fall back on hunches and rules of thumb.

But thanks to recent breakthroughs in brain science, companies can now actually see what goes on inside our minds when we shop. Teams of academic and corporate neuromarketers have begun to hook people up to functional magnetic resonance imaging (fMRI) machines in order to map how their neurons respond to products and pitches.

Last year, the journal Neuron published an article called “Neural Predictors of Purchases” by a group of scholars from three leading U.S. universities. The researchers described how they had used brain imaging to monitor the mental activity of shoppers as they evaluated products and prices on computer screens.

By watching how different neural circuits light up or go dark during the buying process, the researchers found they could predict whether a person would end up purchasing a product or passing it up. They concluded, after further analysis of the results, that “the ability of brain activation to predict purchasing would generalize to other purchasing scenarios.” Forbes heralded the study as a milestone in business, saying it marked the first time researchers have been able “to examine what the brain does while making a purchasing decision.”

At McLean Hospital, a prestigious psychiatric institution affiliated with Harvard University, an advertising agency recently sponsored an experiment in which the brains of a half-dozen young whiskey drinkers were scanned. The goal, according to a report in Business Week, was “to gauge the emotional power of various images, including college kids drinking cocktails on spring break, twentysomethings with flasks around a campfire, and older guys at a swanky bar.” The results were used to fine-tune an advertising campaign for the maker of Jack Daniels.

As you’d expect, a new group of high-tech consulting firms, with names like NeuroFocus, Neuroconsult and EmSense, have sprung up to help companies deploy neuromarketing. The neuromarketers are playing a prominent role at Re:think, the Advertising Research Foundation’s annual convention, which is being held in New York this week. The New York Times says that the agenda is “filled with presentations” on the new scientific approaches to marketing.

In the future, it seems clear, marketers won’t have to ask us what we think or try to decipher our intentions from our actions. They’ll be able monitor what we think directly – at the cellular level. That’s good news for companies. Not only will they be able to spend their marketing budgets more efficiently, but they’ll be able to wield more influence over the purchases we make.

The question is when does influence cross the line into manipulation? If businesses gain the ability to know more about what and how we think than we do ourselves, they’ll also gain the power to control our perceptions and even our behavior in ways we won’t be able to detect. Should neuromarketing achieve even part of its potential, it promises to tip the balance of power in the marketplace from the buyer to the seller.