Biometrics and Experimental Consumer Psychology

Ben Ambridge

Biometrics are playing an increasingly important role in conversion optimisation; but what exactly do they tell us? And, more importantly, how can we use that information to optimise consumer behaviour and drive sales?

In the second of our five-part blog series looking at all of the major biometric techniques, we will be summarising the state of the art of consumer psychology research using EEG (Electroencephalography).

Electroencephalography, or EEG

EEG tells us – literally – what is going on inside a customer’s head when they view a site. Brain cells communicate using electrical signals, and when a thousand or so of these cells are “firing” at once, they create an electric field that can be picked up by electrodes attached to the head.

This allows us to see which parts of the brain are working particularly hard, and to observe changes that take just a fraction of a second. How does this help us? Well, experimental research tells us that certain patterns of cell firing – or “signatures” – are linked with particular emotions or behaviours.

Frontal Asymmetry

Probably the best-known signature, in terms of consumer research, is known as “frontal asymmetry”, which means that the front-left part of the brain is working harder than the front-right. Conventional wisdom in “neuromarketing” says that frontal asymmetry is always a good thing: it means that the customer likes and wants what she is seeing.

And, indeed, a 2009 study by Rafal Ohme1 and colleagues at the Polish Academy of Sciences found that an EEG measure of frontal asymmetry was able to detect tiny differences between more and less effective versions of an advert (for a skin-care product); differences that customers did not even notice (e.g., whether or not a female model made a particular gesture).

But beware! This conventional wisdom is an oversimplification: Frontal asymmetry can also indicate short-term memory load (as summarised in a recent review paper by Reza Habib2). So, sure, this signature could mean that your customer likes what she’s seeing; but it could also mean that she’s struggling to process or remember it.

Late Positive Potential

A less well-known – but potentially more important – EEG signature is the “late positive potential” (so called because it appears almost a second after the customer sees the site, which is “late” in terms of usually-lightning-fast brain processes).

This signature appears when we’re seeing something very unexpected, for example reading “mean” as a description of a person who has just been described as “kind”, “gentle” and “tolerant” (as in a 2009 study by John Cacioppo3 at North-western University).

In the context of a website, this could indicate that a customer has spotted a product they hate in amongst a range of products that they love (or vice versa).

But, again, it’s not always so straightforward: A University of Florida study4 from 2000 found that this EEG signature also appears when people view things that get them worked up, whether the content is erotic or violent. This suggests that the late positive potential could be useful for checking whether a site designed to cause an emotional response is really doing so.

Laterality Shift: That which makes adverts memorable

Finally, two studies used EEG to investigate what makes an advert memorable and effective. A study by Michael Rothschild5 tested customers on their memory for particular parts of an advert. Rothschild found that he could predict which parts of an advert customers would remember by looking out for a “laterality shift” – activity increasing in the right-hand side of the brain and then shifting to the left.

More recently, a 2017 study by Samuel Barnett6 found that both memory for a particular advert and – more importantly – subsequent sales were predicted by the extent to which customers (he studied 58) showed the same EEG patterns. That is, if everyone showed similar EEG patterns in response to the advert, they tended to both remember the advert and buy the product.

So, if your tests show similar EEG profiles for all of your participants, your site is probably onto a winner.

As this whirlwind tour of EEG research has shown, it is never as simple as “this EEG signature means the customer will buy”. The same signature can indicate different things in different contexts (e.g., motivation or memory load; surprise or sexual arousal), meaning that it is always vitally important not only to run your own tests, but to know how to interpret them.

And with years of experience in Biometric Research, we at Endless Gain are both the pioneers and the masters.


1. Ohme, R., Reykowska, D., Wiener, D., & Choromanska, A. (2009). Analysis of neurophysiological reactions to advertising stimuli by means of EEG and galvanic skin response measures. Journal of Neuroscience, Psychology, and Economics, 2, 21–31.

2. Habib, R., Nyberg, L., & Tulving, E. (2003). Hemispheric asymmetries of memory: the HERA model revisited. Trends in Cognitive Sciences, 7(6), 241-245.

3. Cacioppo, J. T., Crites, S. L., Gardner, W. L., & Berntson, G. G. (1994). Bioelectrical echoes from evaluative categorizations: I. A late positive brain potential that varies as a function of trait negativity and extremity. Journal of Personality and Social Psychology, 67(1), 115.

4. Cuthbert, B. N., Schupp, H. T., Bradley, M. M., Birbaumer, N., & Lang, P. J. (2000). Brain potentials in affective picture processing: covariation with autonomic arousal and affective report. Biological Psychology, 52(2), 95-111.

5. Rothschild, M. L., & Hyun, Y. J. (1990). Predicting memory for components of TV commercials from EEG. Journal of consumer research, 16(4), 472-478.

6. Barnett, S. B., & Cerf, M. (2017). A ticket for your thoughts: Method for predicting content recall and sales using neural similarity of moviegoers. Journal of Consumer Research, 44(1), 160-181.