People Care About Sustainability… But Do Shoppers?

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Sustainability has been a top trending topic on the marketing arena for the last decade, engaging brands and customers into discussing its relevance about the role that different market actors are called to play. Despite the efforts, either pretty insulated actions or collective efforts, purchase behaviour is a rough pattern to be shaped. This reluctance to change might root on the emotional and physiological substrates of our brain and its correlates with buying intention. This study aimed to describe the pre-frontal cortex activity while observing brand ads targeting sustainability.


The marvel of the human brain never ceases to amaze us. Consuming a staggering 20% of the body’s energy, it humbly operates in the background, tirelessly keeping the brain and body running smoothly, largely unnoticed. Astonishingly, the brain’s capacity for information processing is nothing short of remarkable, capable of handling up to 10 million bits per second. Unfortunately, our conscious mind can only process up to 50 bits, leaving us blissfully unaware of the vast amount of mental activity transpiring beyond our awareness.

The brain is a master of self-maintenance and adaptation, seeking to operate within its optimal range of functioning at all times. It swiftly resolves challenging thoughts or tasks by reducing them to more energy-efficient and cost-effective methods of guiding behavior in terms of our physiological and emotional resources. The result is an effortless display of mental agility that often goes unnoticed, outside the mindful radar of our consciousness.

When we consider the sheer number of decisions we make every day such as picking a product, it becomes clear that we don’t have the luxury of being entirely logical, rational, and conscious about every single thing we do.

In fact, there are estimates that suggest we make approximately 30,000 decisions per day, a dizzying array of choices that would be unreachable for our brains to process entirely on a conscious level. The blend between top-down processing (conscious control) and bottom-up processing (subconsciously driven) of the brain allows us to navigate our daily lives with remarkable easiness and adaptability.

We need a more efficient way of getting stuff done, otherwise we’d never get out of bed in the morning, so much less go shopping!


To get into a ‘more efficient way’ we require our Subconscious Mind to help us deal with the uncertainty and solve daily problems. The idea of all these bottom-up processes running in parallel tends to startle people, since over 90% of brain activity is non-conscious and happens below our level of awareness. To put it plainly, a lot of the time, we’ve actually no real idea why we make most decisions, they just happen. So, despite what we might like to say about ourselves, we’re barely rational, conscious or logical – and we have a limited insight into why we do the things we do, therefore when trying to study purchase intention, shopper might lie to you, but the brain does not.

Shifting consumers towards more sustainable ways of thinking and behaving is a serious challenge – as the brain doesn’t like change. The mental and economic models that we use to interact with the market have been built and reinforced over years by the traditional linear economy, praising accumulation, self-interests and social acceptance, which is an approach that is engrained within us.

People in general, have little direct insight into the factors that drive their behaviour – particularly shoppers! We buy based on Emotions, Motivation & Historical Rewards from past purchases in particular and our life in general. Processing millions of data points per second and make a decision in the blink of an eye.

To understand decision making, we can’t simply ask consumers why they bought X, or didn’t buy Y. Because more than likely, they can’t tell you the truth – the part of the brain they use to explain the purchase, isn’t the part of the brain that made the decision.

Through Neuroscience we can step away from the presumption that consumers are rational decision makers, and delve into decision making as it is far more complex than what just people say in a survey or interview.


The Say-Do Gap

Conscious consumers have come to realise that their current consumption practices are not sustainable, and a growing number express a desire to adopt more environmentally friendly behaviours. However, there is still a substantial gap between their stated willingness to engage in the circular economy and their actual behavior.

The truth of the matter is that sustainable behavior is challenging. When presented with a choice, we tend to opt for the easiest solution to accomplish our goals. Sustainability, on the other hand, often requires additional cognitive and behavioural effort, which can be perceived as a cost. For sustainable behaviour to become a habit and close the say-do gap, the brain must balance the emotional and physiological resources required against the perceived benefits from a purchase. The challenge, then, is to find ways to motivate sustainable behaviours by shifting the cost-benefit trade-off.


Perceived Value = Expected Value – Discount for Cost – Discount for Mental Effort – Discount for Delay of Realisation

When we evaluate expected reward of a purchase, it’s perceived value can be calculated by the Expected Value:

  • Minus the Discount for Cost
  • Further reduced by the discount for the mental effort to determine the uncertain validity of claimed environmental benefits
  • Then finally, less the discounted for the delay in realising the value of the environmental benefit. This is an important one as humans tend to value lesser rewards received sooner, to greater rewards received later.

The challenge with motivating consumers towards sustainable shopping is that, if you ask people to use more mental effort evaluating the validity of an environmental claim, and then ask them to pay more for a product that offers uncertain outcomes & delay discounting, what do we expect people to do?

Shoppers are unlikely to choose more demanding and costly products – in exchange for a short moment of gratification for doing the right thing on an abstract level, for benefits that might accrue to someone else in the distant future.


The objective of the research was to evaluate the effectiveness and impact of Sustainability Messaging against Traditional Promotional and Purpose-Driven Messaging and for both luxury and commodity goods. We used a combination of EEG Brain Scanning, Eye Tracking & Facial Expression Analysis to test 30 messages, from 30 brands on 30 participants.

The messages / content selected was classified by three message categories

  1. Traditional Promotional: Typical creative or promotional advertising
  2. Sustainable: environmental related messaging
  3. Purpose Driven: Cause based marketing for topics such as Social Justice, Gender, Mental Health and more

We included Purpose Marketing as a condition within the study because typically, in marketing Research, purpose marketing and green marketing have not been differentiated from one another. Recent studies have demonstrated that they impact different audiences in different ways. Which intuitively suggests that both categories of message trigger different responses within the brain.

Furthermore, purpose and environmental related messages are often critiqued through a similar lens of scepticism, and we wanted to understand the variance between both categories.

The topic of sustainability has never been investigated in this way before, as approaches are like this are quite novel. We executed



So the first area we looked in was the Approach-Avoidance – using a measure called Frontal Asymmetry that is collected from our Pre-Frontal Cortex. The principle being we approach what we want we avoid what we find off-putting. Approach Behaviour has been proven to be strongly correlated with Purchase Intent.

So when reading the chart below:

  • Positive Values = More Approach Behaviour (i.e. Traditional & Sustainable)
  • Negative = More Avoidance (i.e. Purpose)


  1. Sustainability Messaging in general triggers mild ‘Approach Behaviours’ – Particularly relative to Purpose Related Messaging.
  2. Traditional Advertising approaches are 10X more effective
  3. While sustainable messaging works in principle – traditional creative messages would represent a better return on investment


We then drilled down to a deeper level, classifying the messages into their respective categories (Luxury & Commodity) and we found some interesting points. What you’ll below, is that in simple terms, Sustainable Messaging worked for Luxury Goods and did not work for Commodity Goods.

For luxury goods, the level of consideration is higher and consumers are more willing to expend mental effort to evaluate the purchase decision which makes the message more receptive to sustainable messaging.

Interestingly, for Purpose Related Marketing, there was an inverse effect effect where Purpose messaging had a negative effect for luxury goods & a mildly positive effect on commodities. This needs further investigation and analysis in terms of individual differences , but our hypotheses are:

  • That there is a consensus on the imperative nature of the environment while there could be increased variability over the importance of some of the topics included within Purpose Marketing.
  • Secondly, it could be related to pure scepticism about the appropriateness of the brand’s position on these causes – and the brand’s true intentions

From a sustainability perspective, the key insight is that Sustainable Messaging isn’t a ‘One Size Fits All’, it is more nuanced than that. It has been shown to be particularly effective for Luxury Goods but it quite off-putting for Commodity Goods.


As has been explored above, when people are asked whether they want to contribute or purchase sustainably, they will more than likely provide over-index with strong measures of intent, in other words their attitudes.

However, what we can see within the data is that by measuring Approach-Avoidance directly from the Pre-Frontal Cortex, we can identify the Neural Correlates, or to put it plainly, the indicators of purchase behaviours based on the objective emotional response of a group while experiencing Sustainability Messaging.

In short, what you can see in the graph above is that Approach Behaviour predicts purchase intent and Avoidance Behaviour predicts the inverse.


In addition to Approach-Avoidance we also looked at how the different messages affected the brain from a memorisation point of view across the various conditions. Memorisation was measured using the Mean Power Spectral Density (PSD) for cognitive activity within the Theta frequency

Interestingly, what we found was that Sustainable Messaging performed the strongest in terms of learning and memorisation activity within the brain. It is important to note, this doesn’t necessarily reflect Brand Memorisation, it is most likely related to Prior Knowledge & Heuristics that are embedded within social constructs, essentially tapping into existing memory structures about Environmental Messaging

The key takeaway here is that Sustainability is a powerful message – but a risky approach because your brand gets lost as the message can overshadow the brand


Consumers Consciously care about sustainability – but we don’t consume or purchase consciously

So, to summarise our three key insights from this research:

  1. Who’s Doing the Shopping?
    The part of the brain that wants to be more sustainable, is not the same part of the brain executes decision making in retail settings.
  2. Why Is Sustainability So Hard?
    Asking a person to expend more mental effort making a purchase decision and asking them to pay more for a product that offers uncertain & temporally distant benefits over alternative choices – will not drive changes in behaviour.
  3. How Effective is Sustainable Messaging?
    • Traditional  & Creative messages are over 10 times more effective than Sustainability Messaging
    • Sustainable Messaging works for Luxury Goods, but does not work for Commodity Goods
    • Approach-Avoidance measures predict purchase behaviour
    • Sustainability can trigger learning and memory – but the brand can get lost in the mix


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