An interview with Professor Geraint Rees


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An Interview with Professor Geraint Rees

As professionals we should constantly be learning about, and frequently learning from, the knowledge and experience of others in the field. For the next few of my blogs I will be presenting edited interviews with some of the leading players in the field of neuroscience, marketing, and retailing. In the first of these Professor Geraint Rees, Director of the Institute of Cognitive Neuroscience, University College London, discusses the two main technologies used by neuromarketing companies – EEG and fMRI. How, in his opinion, had these advanced over the last decade?  



Professor Geraint Rees: “EEG is a stable, mature technology that has been around – [he pauses to think] – well since a very long time. There have not been many technical developments within EEG in the last 10 years. I would have thought that the main developments have been in the way data can be analysed and, in particular, putting the data into frameworks where it can be combined with data from other imaging techniques – such as functional MRI. The software packages now used to analyse functional imaging data, like SPM, or Statistical Parametric Mapping can also be used now to analyse EEG or MEG (1) data. That facilitates data fusion, that is, looking at how a mental process in the human brain operates, combining data from two different techniques. That was quite fashionable, five years ago. With functional MRI, in the last decade, I think it’s a technology that’s rapidly matured. Twenty years ago, it was brand new –it was the new-new thing and it was super hot. And that meant a lot of exploratory studies got done, a lot of things got found out very rapidly. At the same time, there was a lot more heterogeneity in how people analysed their data, and how people reached the conclusions they were going to reach. Perhaps the second phase of that has been, as with any technology, not only has the hardware matured, but also the way in which the data analysed has converged internationally into widely agreed standards, that are – not universally – but near-universally applied. So the field feels a lot more mature in terms of that respect. The hardware has continued to evolve, but I would describe it as incremental, rather than revolutionary. The revolution was inventing B.O.L.D (2) contrast functional MRI in the first place. Since then, there have been repeated advances in terms of the field strength of magnets at which data can be acquired and that, in turn, either increases your sensitivity to detect more subtle effects in the brain, or you keep the same sensitivity, but can get higher spatial resolution. So you can see more bits of the brain and in more detail.



That’s probably the biggest drive, together also with something called parallel imaging, where you can acquire more data, faster, that again allows the same improvement, so the end user is seeing data that are either more sensitive to small changes in the brain, or are more spatially fine-grained, compared to previously. Those have been the main technological developments.

Professor Rees



In EEG, the intrinsic problem is you can never fully determine the pattern of sources in the brain that produce a pattern of EEG waves. For a mathematical reason that is unfixable. This problem is not solvable, or not uniquely solvable. That doesn’t mean that one can’t guess at what pattern of sources, or patterns of activity in the brain made the particular pattern of activity at the scalp that you observe. It just means it’s not uniquely determined, which means you can’t ever be precisely certain. A second, intrinsic, barrier to the nature of the EEG signal is that it’s relatively insensitive to deep brain structures. So the nuclei that live in the middle of our brains that, for example, are affected in Parkinson’s (disease) are not easily accessible to any technique that records the scalp EEG – [which is] much more sensitive to stuff on the surface of the brain. And those are intrinsic and are probably not going to be overcome anytime soon. With functional MRI, the mostly widely used form of functional MRI, B.O.L.D. or Blood-Oxygen Level Dependant, is contingent on the level of deoxyhaemoglobin in the blood. The intrinsic limitation there, whatever the special scale at which blood flow is regulated, is the ultimate spatial resolution on functional MRI, because you are not going to get below that – or you’re going to get below that with difficulty, and inferences, and assumptions. We’ve known for a long time, since experiments in the 19th century, that blood flow changes in the brain are very closely localised to where neural activity changes, to within a millimetre or two. Now a millimetre or two is great – right? I mean, absolutely fantastic for the kind of science I do. But on the other hand, to some people, a millimetre or two is hundreds of thousands of nerve cells, and so that’s a huge distance. It reflects the fact that the brain has these multiple levels of organisation at different spatial scales.



For a technique at one spatial scale to talk, or inform another spatial scale is not always possible, or is more challenging if there are intrinsic limits like this… there have been repeated attempts to get round that; some people have tried to devise MR sequences that, for example, are sensitive to electrical currents. But these generally have not entered wide usage, and are generally speaking, highly technical and not as powerful. Why B.O.L.D contrast fMRI has become the de facto standard is not because it’s the best signal, but it’s because it’s the signal that’s easiest to produce and is jolly reliable. As these things go. So there’s an intrinsic limit of course that many people appreciate, because it’s a blood flow response, which is also temporal. So the timing of the blood flow response lags neural activity by several seconds. But…we don’t know for sure, because people haven’t done a kind of mapping experiment to map out that latency across the whole brain. The reason they haven’t done that is because you’d need to be able to precisely activate every single portion of the brain and you don’t know precisely what to do to do that, to actually make the measurements in the first place. There’s no particular reason to expect wild differences because, of course, given that brains have grown, like the rest of us, from very small numbers of cells, in the embryo. That said, there are some regions of the brain, like, say the cerebellum, where the architecture of the nerve cells is quite different. So you might expect or anticipate or hypothesise that the blood flow response is different. Usually that isn’t a problem for experimenting, because you’re comparing an experimental manipulation in that brain region – you’re not normally comparing what’s happening in one brain region, to another.



You’re looking at what’s happening in a brain region, under two different circumstances. So there are ways round that particular problem – it’s recognised in the field, basically. Within marketing, generally, with honourable exceptions, there’s often a surprising lack of knowledge about whether it works. So for example, I went to a conference where one company gave a very interesting presentation about how difficult they found it, working out whether advertising made any difference to sales. They went to the trouble of essentially randomising half the customers in one town, to receive adverts for one store, or not. Then working with that store to actually determine whether that made a difference in sales. So a really good experiment – well controlled. The challenge they had, was they did observe an effect, a positive effect, but it was so small, and the variability in what people spent at this store, because it was a general – I presume – department store, was so big, that the effect size they were measuring, even with tens of thousands of customers, they found it very difficult to actually say this is definitively a statistically significant difference in marketing. But that said…that difference, multiplied by the number of consumers, was a big difference to their bottom line. So very relevant. That’s not Neuro marketing – they were just doing classic marketing. But I had a lot of sympathy for the challenge they faced in determining whether a large-scale intervention has a very small effect on a very heterogeneous population. It’s not easy. Of course, recording EEG in the wild is always going to be worse than recording EEG in controlled laboratory conditions. Not so much because of the uncontrolled nature of the environment, but because of the electrical interference of everything around us that is electrical…as long as the signal is reflecting the EEG signals, fine. It’s then just a pragmatic issue of, is the signal enough to provide something useful that can correlate, or provide insight, into some behaviour? If it is, it doesn’t matter that it’s not the best in the world.



I was reading a Psych-science paper showing that fMRI responses in a focus group predicted the effectiveness of a marketing campaign. I thought that was a good paper – and it was really interesting. Because that was conceptually doing a really interesting thing, which was saying you can do a high quality laboratory based fMRI study, and a focus group, and it generalises to a large-scale phone survey. Again, from the conceptual issues, that is interesting because that says you don’t have to collect lots of data, badly, from lots of people, and draw a conclusion from noisy data. You can actually do this, but under these kind of circumstances. So if you could understand, for example, the circumstances under which that generalisation works, then that becomes a very useful tool. In the same way that presumably focus groups are useful tools in marketing generally, because the focus group can be generalised to the population.” End





[1] Magnetoencephalography (MEG) a technique for mapping brain activity by recording the magnetic fields produced by naturally occurring electrical currents.

[2] BOLD – Blood Oxygen Level Dependent. A technique for mapping brain activity by measuring changes in blood flow to different regions. The full version of this interview, conducted by Mindlab’s Tom Dixon, can be found at www.the-brainsell.com 


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Neuromarketing Myths (No. 3) – It’s too inaccessible and expensive

neuromarketing myths

Old School MythsHere’s the third post in the Neuromarketing Myths series.  Here we will try and remove some of the mystery surrounding our profession, and address the most common misconceptions we encounter on a day-to-day basis.

I could argue that if the research is really good then there’s going to be an excellent ROI. Fair point, but if you spend all of your research budget on new fangled neuromarketing and get no insight then you’ll soon be looking for a new job. PeoplBrain With Arms, Legs And Magnet On Hands, Catch Many Euro Bankne are loss averse (I know you knew that already). Insight specialists are no different. The status quo bias reminds us that change can seem as a loss so shifting over to new approaches is difficult enough but shifting to expensive new approaches is too big a step to take.

One of the reasons that fMRI and EEG based research isn’t as popular as the press actually suggests is that it’s expensive to do right. This is especially so if the testing is to be done on more than 100 people. The anchoring effect of neuromarketing prices from 10 years ago lingers but the truth is that you can now get comprehensive quantitative insight into emotions, attitudes and perceptions for the cost of many traditional market research approaches.


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Neuromarketing Myths (No. 2) – It’s all about brain scans

neuromarketing myths

 

Old School Myths

Here’s the second installment to our Neuromarketing Myths series. Neuromarketing techniques are increasingly being used by companies in order to test their brand perceptions, new concepts, products, packaging, communications and much more. Its use is so widespread that it is surprising how much misunderstanding there still is around neuromarketing. Here we will try and remove some of the mystery surrounding our profession, and address the most common misconceptions we encounter on a day-to-day basis.

 

It’s all about brain scansModern Examination In The Hospital

It is true that neuromarketing started out with a strong focus on technologies such as fMRI (brain scans) and EEG (measuring electrical brain activity). Modern neuromarketing now however is much more about scalable psychological and cognitive tests that can be carried out online. This is not just because they are cheaper,  faster to turn around and allow us to test many more participants, but also because they tend to provide clear and comparable data that can directly answer many market research questions. Automated facial encoding using webcam and implicit testing (refered to as IAT or IRT) is now becoming mainstream.

 

Neurobollocks

Many people who don’t have a background in psychology and neuroscience seem to believe that brain imaging techniques such as fMRI will give them better answers. Research has shown that people are more likely to be convinced by statements if these are presented next to a brain image and they seem to be similarly seduced by the idea of brain scanning in market research. But results from these studies are often much less clear than they may appear.

Neuromarketing has had some bad press, quite rightly at times. One particular neuromarketing study was lambasted after a New York Times OP-Ed piece compared iPhone addiction to cocaine use and falling in love because the insula’ lit up. The problem is that the insula lights up for loads of things. The same brain area may also be involved in working memory, physical pain, disgust, anger, visual perception, motor sequencing, and memory retrieval.

Insight professionals want to better understand the mechanisms of decision making and neuromarketing can and does help. It’s just a shame that some people get it so very very wrong and make the industry look stupid.


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Neuromarketing Myths (No. 1) – We can brainwash you!

neuromarketing myths

Old School Myths  Neuromarketing techniques are increasingly being used by companies in order to test their brand perceptions, new concepts, products, packaging, communications and much more. Its use is so widespread that it is surprising how much misunderstanding there still is around neuromarketing. Here we will try and remove some of the mystery surrounding our profession, and address the most common misconceptions we encounter on a day-to-day basis.

 

We can read minds (and brainwash you)

One of the most common things we hear when new clients first get in touch with us (or even when we just talk to friends about our jobs) is that they feel there is something ‘spooky’ or ‘scary’ about what we do. People either seem to think that we try and ‘read their mind’ to uncover aspects of themselves that they weren’t even aware of, or brainwash them into buying the latest product, or both.

Let’s be clear here: WhileMind Control it’s flattering that you put this much faith into our abilities as psychologists, neuroscientists, market researchers and data analysts, we’re really not that great. What seems to create this fear in people is neither currently possible nor desirable. Fundamentally, we try to answer the same questions as traditional market research, we just believe we have a better approach to it. Instead of just asking people for their opinion, we measure things such as their gut feelings about a product, how their opinion about a brand has been (very subtly) changed by communications, and whether they pay attention to an advert or not.

None of this has anything to do with brainwashing (not any more than advertising always has) or subliminal messaging. We are simply capturing people’s opinions and attitudes in a more effective way than traditional market research alone does.

Every year $billions are spent on ineffective market research. The aim of neuromarketing is to make market research spend more effective.

 Mindlab offers the most accurate and effective market research available because we don’t just ask people what they think, we find out how they feel.


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Be Strategic – Really?

strategic

Last week I was invited by Digital Annexe and ISBA to talk at ISBA’s Insight and networking event entitled ‘The Next 5 Years in Digital’.

It was great to see such a strong presence from Asda, Morrison’s and Nestle.

Sean Singleton from DA talked about the 7 habits of digital marketers (borrowed from Steven Covey’s 7 Habits of Highly Effective people).

The habit that stood out for me was ‘Be Strategic’. This seems blindingly obvious but most people don’t think long 7 Habitsterm. Sean argues that marketers are too focussed on driving more traffic to their websites but then fail to engage customers with the correct approaches to increase site conversion.

I think that this short term thinking is a ubiquitous problem in business and goes some way to explain why traditional market research dominates the market place and why the science of decision-making has not had more of an impact on marketing. This is despite compelling evidence from countless psychologists and neuroscientists that clearly demonstrates that the majority of our decision making processes occur below our conscious radar.

To translate the findings of decision sciences into marketing practices takes time. The fact that the average tenure of Chief Marketing Officers is just 45 months and the continual demand for short term results means that people are more worried about keeping their jobs than fixing the long term problems with a bloated over-emphasis of explicit self-report in market research.

I regularly speak to insight professionals who have read Thinking Fast & Slow by Daniel Kahneman or Predictably Irrational by Dan Ariely. These people even have a passion for decision sciences and understand that there is a key role in non-conscious processing in decision making but constantly come up against barriers when they discuss ideas of change with colleagues. Marketers need to spend time understanding how people make decisions. This is relevant to all categories but isn’t being done on anything like the scale that it should.

As humans we make mistakes and behave in irrational ways, which is reflected in cognitive biases. The reticence of researchers to change their approaches is, in some way, due to confirmation bias. When we make decisions, such as investing hundreds of thousands of pounds on traditional market research, our brains seek out evidence to make us think that we made the right decision. We are essentially blind to evidence that says the decision was wrong. We like it when a decision feels good.

Sean also states that as a key habit, we should create a culture of experimentation. Too true. New approaches need to be experimented with and validated – a process that takes time. Progressive marketers would be well advised to try out behaviourally based approaches that interrogate our non-conscious minds without post rationalisation. This can easily and cost effectively be done on small projects to introduce new thinking.

‘Be strategic’ may be one of the most overused phrases in business. It may well also be one of the most misunderstood.

Duncan Smith


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An idiot’s guide to neuromarketing – Mental shortcuts

We all know that for certain behaviours, our brain more or less switches to ‘autopilot’. When walking from A to B, you don’t constantly think about every single step that you take, or about how you have to hold up your head, breathe, and balance your body. Similarly, you might remember that the first few times you drove a car, you had to pay close attention to every single action involved in it, while you probably barely remember your last trip home from work.

These behaviours are often explained by saying that ‘your body remembers how to do these things’, or using words such as ‘muscle memory’. So while we understand these shortcuts with physical examples, we often forget that our mind functions in a similar way.

 

Our mental shortcuts influence how we see and perceive the world, how we think and reason, and how we make decisions.

Our behaviours, as well as concepts that have an impact on us, are represented by neural activity in our brains. Every time two behaviours occur at the same time, or two concepts are encountered together, our neural connection between them becomes stronger. This is often described with the sentence ‘cells that fire together, wire together’. In reality, it’s a bit more complicated than that, but it is true that the connections we make between behaviours and/or concepts are reflected in neural networks, and grow stronger the more we encounter these links. This is why you press the clutch pedal and change gears without having to think about linking these behaviours, but also why you associate the taste of an orange with the colour orange.

 

Associations like these get built and used constantly, without us necessarily being aware of them. Dan Ariely believes we are the sum of our early decisions – the product of what he calls an arbitrary coherence of choices that we made long ago (or were made for us). As a result, in many cases, we make decisions that are simply the reflection of our initial choices.

These initial decisions become anchors that take root and resonate throughout our later lives much more than we would like to acknowledge. Our associations help us learn new concepts and avoid dangerous situations (e.g. walking through a dark alleyway or touching a hob), but are also what makes us prejudiced and jump to conclusions. They do however also help us make choices, and that’s where it gets interesting for market research. The vast amount of visual as well as factual information available to us when making pretty much any purchase decision is overwhelming, and we use the connections we have already established to help us make our choice. This can be reflected in the use of heuristics and biases, but even if the decision seems pretty rational to us (and we might be able to come up with an explanation for our choice afterwards), our behaviour is strongly influenced by these links and associations. It might be something as simple as picking one bottle over another because the label colour reminds us of our childhood home.

What does this mean for market research?

Traditional ‘asking methods’ such as surveys and focus groups require people to reflect on their behaviour, opinions and decisions as well as predict how they would act in the future. However, most of the time we don’t understand the associations and connections that underlie the decision-making processes. We still try to come up with explanations for our behaviour when asked to reflect on it, but the reasons we give often have little to do with what really drove our decision. In order to understand what drives behaviour, we need to understand what connections between concepts and associations are common. This means exploring and quantifying what concepts are connected with a brand or an advert, and how communications can be used to strengthen positive associations as well as weaken undesirable ones. Because these (often emotional) connections are what can make or break a purchase decision, it is important to explore them, rather than relying solely on the post-rationalisations people come up with when asked about their decision.


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The Scottish Referendum


 

Mindlab offers the most accurate and effective market research available because we don’t just ask people what they think, we find out how they feel.


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Groupthink and focus groups

Have you ever sat in a group discussion and stayed quiet because you were worried that you were wrong, or that everyone else had a different opinion from yours? Most of us have been a victim of ‘groupthink’ in one way or another. It affects political discussions, work meetings, focus groups and pretty much any situation in which groups try to solve a problem, or come to a consensus decision. Groupthink was first talked about by Irving Janis in the 1970s and has been used to explain bad decision-making in many different contexts. But before I talk about how it has an effect on work or focus groups, let’s focus on one of the prime examples of groupthink:

The Attack on Pearl Harbour

Before Pearl Harbour was attacked on 7th December 1941, internal Japanese messages had been intercepted and it was discovered that they were preparing for an attack in the Pacific. As a result of this, Washington sent a warning to the officers stationed at Pearl Harbour. But why was this warning not taken seriously enough to prepare for the attack? Discussions led the Navy and Army to conclude that the attack was unlikely, and they rationalised their opinion in many different ways. They assumed that the attack would only happen as a response to the US attacking Japan, and that Japan would surely not be crazy enough to start a war that they couldn’t win. Also, the officers thought that even if the attack should happen, they would be able to detect and destroy the fleets before they could reach the base. What does groupthink have to do with these conclusions, and how does it affect our everyday decision-making?

When Janis developed his theory, he named three groups of symptoms that groups suffer from when making a decision: overestimating the group, closed-mindedness and pressure towards uniformity.

Overestimating the Group

According to Janis, group members overestimate their group in two ways: They think they are invulnerable, and they don’t question the morality of their group and the decision it makes. Pearl Harbour suffered from both of these: Overestimating the power of their country (which led them to take the risk of not preparing), and believing to be in the right, supporting the right cause, and therefore ignoring the consequences of their actions (or non-actions in this case). Focus groups are more strongly influenced by the first factor: They are a completely invulnerable group, because they will never be held accountable for their decisions. This encourages the group members to voice support for riskier options than necessary, which can end up costing a company millions.

Closed-Mindedness

But you don’t need to overestimate the group in order to make bad decisions: Group members also tend to rationalise their group decisions and stereotype those who aren’t part of the group. In the Pearl Harbour example, both of these factors played a role. The officers used rationalisations to ignore the warning signs and stereotyped the Japanese army as being too weak and scared to attack the US base. In focus groups, these factors are seen in a more subtle way. The aim of focus groups (and most work discussions) is to come to a consensus decision, which means that they are prone to ignore minority opinions. Additionally, focus groups assume that their opinion is representative of everyone ‘in their right mind’, and ignores people who aren’t represented in the group. Most of the closed-mindedness of focus groups, however, stems from the third group of symptoms:

Pressure toward Uniformity

The pressure toward uniformity arguably has a lot to do with the fact that groups try to reach a consensus decision, and Janis describes the symptoms related to this in four different ways: Self-censorship, illusions of unanimity, direct pressure to conform and mind guards. Self-censorship is exactly what I talked about in the beginning of this post; if you feel that everyone else’s opinion is different from yours, you are reluctant to speak up. This is especially true if you feel that others are more powerful than you (probably the case in the Pearl Harbour discussion) or if you don’t hold particularly strong opinions (as seen in focus groups – would you start a fight over a new bottle design?). This can result in the illusion of unanimity, because the group assumes that silence is a form of agreement. The direct pressure to conform and ‘mind guards’, people who deliberately shield you from dissenting information, might not play as obvious a role in the work environment and focus groups (one would hope), but might influence political decision-making.

Does this mean that all group discussions are automatically doomed and can never come to a good decision? No, but it helps to be aware of group dynamics and how they can influence your discussion. Next time you are in a meeting, speak up (especially if you don’t agree with the rest of the group!) and try to not get carried away with the flow of the discussion. Be realistic about your options, advantages and risks, and you might be able to reduce the influence that groupthink has on your decision-making.

Mindlab offers the most accurate and effective market research available because we don’t just ask people what they think, we find out how they feel.


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Effective Branding

Gaining strong brand equity is an important goal for every brand. If you want to make your brand as successful as it can be, it is important to understand your brand’s personality, its position in the marketplace and its potential for moving into new areas. These questions can be tricky to answer, even using market research. It requires an approach that is completely individual to your brand and a clear understanding of what you are trying to achieve. There are however three key areas that market research should focus on to fully understand your current positioning, potentials and limitations:

Brand Identity

This refers to the personality of your brand, the nature of its products and what values you want people to associate with your brand. There is probably some visual imagery associated with your brand, and you should get your brand to strongly own this imagery. This is tremendously important, as your imagery can lead customers to feel positively about your brand, induce feelings of familiarity and communicate concepts that are desirable to you, such as quality and affordability. All of this can lead to strong brand equity. It is also important that your brand manages to differentiate itself from its competitors. Asking people how they feel about your brand can provide a good starting point, but you should not stop there: It is (arguably even more) important to find out how people truly and subconsciously feel about your brand, which imagery and messages are essential to your brand and which ones are not making people feel more positively about it.

Brand Space

Your brand does not exist in isolation, and you know this. To improve your brand, it is absolutely essential to understand where exactly it lies within its category and marketplace, and what sets it apart from competitors. People need to easily identify your brand as part of the category, but also see it as different enough to understand why they should buy your products, and not the competitors’. Understanding your positioning is essential when you are thinking of growing and expanding your brand, perhaps taking over new categories, or even if you just want to make people feel more positively about your brand and associate it with the right values. How people feel about your brand is largely driven by their subconscious, and measuring these subconscious feelings can help you carve out a unique space in the market and really stand out from the crowd.

Brand Behaviour

Apart from understanding your brand’s personality and its space in the market, you might also want to find out how flexible your brand is. You don’t want your brand to stagnate, but at the same time know it should stay true to its personality. How flexible your brand is will largely depend on its products and categories, but understanding its possibilities and limitations is essential to make your brand as successful as it can be. For addressing potential brand behaviour, an individually tailored approach is needed. It is important to assess how consumers will react to changes to your brand; reaching into new categories, creating new products, changing brand personality, or changing the focus of brand communications. It is also important to find out what consumers really want; are the planned changes to the brand, products or communications desirable to the consumer? At this stage, it is also worth taking your competitors into account. Can your brand react to your competitor’s changes quickly and efficiently? The way this is tested is similar to testing your brand identity and brand space, but you might be interested in monitoring changes over time as well. The three key areas for effective branding can of course be investigated using the traditional asking methods of market research, but this won’t paint the whole picture. A large proportion of the decisions we make is influenced by our subconscious, and it important to test how people truly feel about your brand using the most effective market research available.

Mindlab offers the most accurate and effective market research available because we don’t just ask people what they think, we find out how they feel.


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Detecting emotions with EEG patterns

The holy grail of consumer research is to figure out how to accurately measure emotions. Emotions are complex, involving physiological, cognitive and social components that come together to create the subjective experience. Consumer decision making is driven by emotions (Schwartz, 2000) that signal us to approach or avoid things in our environment, based on how rewarding we think they will be (Damasio et al., 1996).

Common consumer research approaches to measuring emotion all have their weaknesses (self-reporting, autonomic measures, facial encoding, facial electromyography, fMRI).* Electroencephalography (EEG) is a promising tool, as it measures real-time changes in voltage caused by brain activity, has good temporal resolution, and is less invasive than fMRI. Frontal alpha asymmetries are a commonly used metric in EEG consumer research. Greater left than right frontal alpha asymmetry was originally thought to reflect positive valence in the brain (Davidson, 1992), but research on anger revealed it to be a measure of approach motivation rather than positivity (Harmon-Jones, 2007). However, this asymmetry is affected by trait factors as well as current emotional state (Coan & Allen, 2003), and it is unclear how accurate this measure is on a second-by-second basis.

We sought to use EEG pattern recognition to detect positive and negative emotional responses in the brain. The first challenge was eliciting real positive and negative emotions in a reliable and consistent way. We used several methods including presenting participants with emotive pictures, emotional face images and short video clips, mood induction statements,  emotive music and pure major, minor and dissonant tones. We created our own genuine facial emotional expression database for use in the study**. Participants viewed these stimuli while their EEG was measured. Then a classifier recognised which EEG features (power and coherence) corresponded to positive and negative emotions in each individual. We randomly selected 70% of each individual’s data from the positive and negative conditions, respectively, for each stimulus type. A pattern recognition algorithm learned how to classify the data into two separate categories (positive and negative). We then used the other 30% of the data to attempt to predict whether the participant was viewing or listening to positive or negative stimuli. The result is the percentage accuracy of this prediction. EEG power alone had very poor predictive power, hardly better than chance. In contrast, power and coherence together had excellent predictive power. The stimuli that produced the most accurate predictions were pure tones (95% accuracy); and the stimuli that produced the least accurate predictions were emotional images. This is unsurprising as tones are pure and unimpeded by ‘noise’, while images are varied in their content. The music was also highly predictive (93%); followed by the emotional faces (92%), the mood induction statements (91%) and finally the short video clips of emotional faces (87%).

Although this was a pilot study with a very small sample, this study showed that EEG pattern recognition is a promising method for measuring individuals’ emotional responses to visual and auditory stimuli. Its accuracy depends on the validity of the trained algorithms and its capability to perform on new datasets. Further research will focus on whether this powerful method can be used to accurately predict how people feel towards images and videos of products, people, brands and concepts.

* Self-reporting of emotion is a common approach with many pitfalls. Autonomic measures include heart rate and skin conductance, which are good for measuring the physiological intensity of emotion, but fail to specify whether the emotion is positive or negative. Facial encoding or facial electromyography (EMG) only capture the expression of emotion. Functional Magnetic Resonance Imaging (fMRI) is extremely expensive, has poor temporal resolution, and has ecological validity issues, (participants are placed in a small tube in a noisy magnet and must keep still).

** Most emotional face databases are not available for commercial use, and they use acted emotional expressions. We used a variety of tasks to elicit Ekman’s (1971) six emotions (happiness, sadness, disgust, surprise, anger and fear) while recording 20 participants’ emotional expressions. We chose still images and short clips of the participants showing genuine emotion and had 90 participants evaluate the images on valence and arousal to ensure they adequately represented the desired emotions. The innovative idea of creating short video clips capturing the most intense and convincing emotional responses was to ensure the highest possible level of ecological validity. The resulting database of still images and short clips was used to elicit emotions in the EEG study.

 

References:

Coan, J.A., & Allen, J.J. (2003). Frontal EEG asymmetry and the behavioural activation and inhibition systems. Psychophysiology, 40, 106-114.

Damasio, A. R., Everitt, B. J., & Bishop, D. (1996). The somatic marker hypothesis and the possible functions of the prefrontal cortex. Phil. Trans. R. Soc. Lond., 351(1346), 1413-1420.

Davidson, R.J. (1992). Anterior cerebral asymmetry and the nature of emotion. Brain and Cognition, 20, 125–151.

Ekman, P., & Friesen, W. V. (1971). Constants across cultures in the face and emotion. Journal of Personality and Social Psychology, 17(2), 124-129.

Harmon-Jones, E. (2007). Trait anger predicts relative left frontal cortical activation to anger-inducing stimuli. International Journal of Psychophysiology, 66, 154-160.

Schwarz, N. (2000). Emotion, cognition, and decision making. Cognition and Emotion, 14, 433–440.


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