In a webinar I joined recently, Google Glass was presented as a more cost-effective eye-tracking device than current research technology. But the speaker seemed more excited by the potential to link it to skin-sensor readers that record how the respondent feels during the research.

His contention was that participants in traditional research often lie about how they are feeling - the only way to reach the ‘truth’ with certainty is to replace personal reportage with empirical science.

There’s a huge desire within business for certainty, particularly for food and drink businesses looking to pitch new products. But the temptation to position research as an exact science can be dangerous.

I’ve conducted hundreds of groups, interviews and forums. I’m sure there have been instances when respondents haven’t told me everything they’ve been thinking. But I’ll accept that in exchange for the insight I’ve gained from watching them react and working out what these responses mean.

Sometimes it’s obvious - when a new biscuit disappears off sample plates in moments and respondents ask to take some home it doesn’t take a genius to work out something good is going on. But people often behave in ways that run counter to what they say they will do. There is a reason, but it is often an emotive, irrational one.

There was a recent story on BBC radio about a Japanese invention - a bra that only unclasps when the wearer’s heart-rate indicates ‘love’ - that perfectly illustrates how nonsensical an overly scientific approach can be. The bra ‘works’ by reading heartbeat increase - a possible sign of love, yes, but also fear, a hit of coffee or exercise.

There’s a lesson here: if you want to understand how consumers feel about your brand, trust the irrational, friendly, interpretative mind of a good researcher. Certainty is a wonderful goal, but rarely achievable when it comes to reading human behaviour. And for food and drink businesses, emotive associations are often the real reason consumers come back time and time again to buy their brands.

Chris Blythe is a director at The Brand Nursery