When you’re reaching for the supermarket shelf, are you making an informed and perfectly rational consumer choice every time? Probably not. According to Harvard professor Gerald Zaltman, 95% of purchasing decisions are subconscious.

Zaltman, who has been studying consumer behavior for decades, says that the average consumer doesn’t compare multiple competing brands and price points when evaluating a purchasing decision. What’s more, what consumers say they want to buy often contradicts their actual behavior.

That’s because consumer spending is largely shaped by unconscious and emotional urges. In fact, the vast majority of our decision-making is emotional. This is supported by the fact that people who have sustained brain injuries in areas responsible for processing emotions often have serious difficulties in making decisions.

Antonio Damasio, who has been studying people with damage in the part of the brain where emotions are generated for many years, says these patients are normal in all regards, except that they were unable to feel emotions. The patients could describe what they should be doing in logical terms, they found it difficult to make even the simplest decisions, such as what to eat.

Should I have chicken or turkey for dinner? With no emotional filter, you have to make an imaginary pros and cons list in your brain to make a purely rational decision. But the problem is that this comparison is difficult to make purely on objective grounds, so people are stuck. The implication is that our decisions are arguably always driven by emotions. Let’s not kid ourselves: human beings are not as logical as we might imagine.

A professor of neuroscience at the University of Southern California, Damasio strongly believes that neurobiological research has a distinctly philosophical purpose: “The scientist’s voice need not be the mere record of life as it is,” he wrote in a book on ­Descartes. “If only we want it, deeper knowledge of the brain and mind will help achieve … happiness.”

Successful marketers inherently understand that it is emotions that drive consumer behavior and have adjusted their communication accordingly. Zaltman says that companies would be wise to invest in emotion-based campaigns that sell. He gives an example of a “communications device” that invokes deep thoughts and feelings of social bonding. For instance, the way a product is gripped in the hand and the choice of finish in the device’s housing material could have a much more profound impact on consumer behavior than more abstract product value propositions such as technical superiority or long-lasting benefits.

Luxury goods brands should target the consumer’s feelings of self-worth, acceptance, and status while sports brands could inspire by promising adventure and glory through the act of competition.

Research and development that combines neuroscience and product design will do well to stand out from the pack and profit, Zaltman adds. You have to know the customer in order to launch a successful marketing campaign — and this means knowing which kind of emotional experience you want to provide to guide the customer towards making the purchase.

“Technology is indeed revolutionizing our ability to understand customers. Insights about the workings of the cognitive unconscious including memory, attention, information processing, the nature of human universals, and socially shared cognitions, and the neurobiology of figurative thinking, for instance, have already outdated most thinking and current practices among managers. Many of these advances are the product of advances in research techniques. Still, the use of scientific advances requires the imaginative translation of scientific findings into effective practice in the marketplace. This is the art that goes hand-in-hand with science. Imaginative thinking by managers and market researchers is required to successfully apply insights from metaphor-elicitation and neuro-imaging techniques, for example, to generate helpful new products, more informative communications, and more rewarding in-store experiences,” he said during an interview with Harvard Business Review.