Why Consumers Say Yes While Their Bodies Say No in Market Research

Survey answers did not reliably predict what people bought. That mismatch pushed me out of quantitative research.

Early in my career, I managed consumer-health product research for a pharmaceutical company. I developed new product ideas through large quantitative surveys, showed respondents carefully written product descriptions and forecast sales from their purchase intent. We tabulated results to the decimal point. The data looked precise. The market did not always follow.

During a focus group at the pharmaceutical company, I watched through a two-way mirror as a moderator read a product concept we had tested in the survey. She asked, “If this was available, would you buy it?” A woman clearly said yes while shaking her head no. Neither she nor the moderator noticed, and our team tallied a yes.

I did not treat the headshake as a lie detector, and I never learned what she bought. Still, her answer looked less settled than her voice sounded. From then on, I recorded verbal and nonverbal responses. A yes arrived with a wince, eye roll or furrowed brow. Some respondents delivered an excited “yes” in a deadpan tone.

The written reasons remained well-reasoned and coherent. They were not useless, but they did not provide the clear window into behavior that the market research industry expected. I began to doubt the assumption that honest people could fully explain their answers.

When the pharmaceutical company offered me a paid executive MBA at Columbia, I asked to earn a psychology degree. The company said no. I said no, left and joined a qualitative research firm conducting focus groups and in-depth interviews. I wanted to see the real story emerge before respondents packaged it into words.

Why confident answers can mislead

Years later, neuroscientist Michael Gazzaniga offered a mechanism for the say-versus-do gap that had undermined my quantitative forecasts. In studies of patients whose corpus callosum, the fibers connecting the brain’s hemispheres, had been cut to control severe epilepsy, he showed information to one hemisphere while the other did not see it.

The surgery sharply limited communication between the two sides and made the process easier to observe.

One patient received the word “walk” through his right hemisphere and got up and began walking. When the experimenter asked why, the speech-controlling left hemisphere had not seen the instruction. The expected honest answer was “I don’t know.” Instead, the patient said, “I was thirsty and wanted a drink.”

Gazzaniga called this left-hemisphere function the interpreter: a process that turns an action into the most coherent explanation available. The patient’s reason was sincere, not evidence of deliberate deception. Gazzaniga argued that healthy brains also construct explanations, although they use more information and often reach the right conclusion. The surgery made the interpreter visible by cutting off evidence the brain normally integrates.

The woman was not a split-brain patient; her hemispheres communicated normally, so the cases cannot be compared literally. They shared the same gap: a fluent verbal response did not match her actions. Gazzaniga’s argument extends beyond surgery.

What does this change for market researchers?

It changes the method, not the need for explanation. Researchers should treat a first rationale as a start rather than a verdict. They should record what happened immediately before the choice, compare spoken and nonverbal responses, and use qualitative interviews or observation to find motives a polished answer leaves out.

Researchers at Lund University in Sweden tested the same mechanism in a grocery store. Shoppers tasted jam, named a preferred jar and then tasted it again. The researchers secretly replaced their chosen jam with another. Most participants did not notice the swap.

They still explained the preference with ease after rejecting the original jam. The reasons seemed like honest reports even when they may have been invented.

Hall, Johansson, Tärning, Sikström and Deutgen published the study in 2010 in Cognition, volume 117, issue 1, pages 54–61. Its title was Magic at the marketplace: Choice blindness for the taste of jam and the smell of tea.

The gap can shape larger decisions. A job may feel right, a new relationship may inspire trust, or a remark may trigger a defensive explanation: “I was just having a bad day.” The stated reason may be true without capturing a deeper feeling of dismissal, an unnamed worry or a preference for avoiding conflict.

I argue that people tend to avoid bad feelings rather than try to get what they want. Three examples from the account make the mechanism concrete:

• Choosing a more expensive bottle to avoid looking cheap.
• Agreeing with someone to avoid a fight.
• Delaying an action because of fear about what might happen.

The first explanation often offers the simplest story a person can assemble quickly. I would check whether it fits everything observed, including behavior the respondent initially ignored. The useful analysis is whether the person was moving toward something or away from it.

I never learned what the woman finally did. She said yes, her body said no, and neither response told the whole story. Your explanation may be sincere, but it also might be incomplete.

For marketers, the practical change is to pair surveys with observation and interviews, and to treat a confident answer as the beginning of the inquiry rather than the end.