Taking glucose seriously

People sometimes talk about lacking the ‘mental energy’ to complete a certain task. But relatively few professionals – or their employers – probably give it further consideration.
Yet when it comes to our ability to make decisions, mental ‘depletion’ is a more serious issue than we might imagine. Our brains are energy-efficient machines, which, when low on glucose, limit our expenditure by avoiding effortful mental computations. Cognitive tasks and logical decision-making, such as complex product purchases, consume a lot of energy, so can cause depletion. But they are also the tasks most affected by it.

A powerful example of this is shared by Daniel Kahneman in his new book ‘Thinking, fast and slow’, which relates to the performance of eight parole judges in Israel. These experienced judges have the task of reviewing parole cases and deciding whether to grant freedom from imprisonment. Each case takes just a matter of minutes, with around 35% of requests being approved on average. The researchers found compelling evidence of ego depletion when tracking the correlation between the judges’ decisions and their food breaks:

‘The proportion [of approved parole requests] spikes after each meal, when about 65% of requests are granted. During the two hours or so until the judges’ next feeding, the approval rate drops steadily, to about zero just before the meal.’

Besides being a cautionary tale about the impact of depletion, it’s also an interesting perceptive on the role of defaults: the judges defer to the default of denying parole when lacking in energy, but go the other way when fuelled-up. Defaults are one of the most accessible behavioural economics principles – that humans are prone to ‘going with the flow’ of what’s already in place. But this case is a reminder neither to see defaults in a vacuum, nor to view behavioural economics as a silver bullet.


At the same time, studies like this prompt us to question long-held assumptions about the ability of humans to make rational decisions – particularly in a professional context. It's certain that behavioural economics equips us with useful tools with which to better analyse these choices. For disciplines like B2B marketing, where a model of rational decision-making is still often assumed, this should be valuable food for thought.

Getting energised about behaviour

Last week some of the PrimeDecision team attended Communicate 2011, the annual conference for environmental communicators. There we witnessed a real appetite among the attendees to understand the practical application of the psychology of behaviour. It was fantastic to see Professor Geoffrey Beattie, prolific psychologist at Manchester University, sharing some of his recent findings – and sparking more questions than any other speaker slot.

In a whistle-stop tour of recent research, Prof. Beattie tackled the distinction between implicit and explicit attitudes – and the gap between what people say and what they ultimately do. In one study his team had asked people questions about green purchases while tracking their body-language. Even though they all said positive things about making green choices, their hand gestures would betray the truth – and predictably confirm or contradict what they were saying. In another study the psychologists were able to predict which candidates people would choose from a selection of CVs, based on whether they were holding implicit racist attitudes. It's fascinating that such strong biases can exist in people who are not consciously aware of them. The team are also doing extensive work with eye-tracking to understand how people process environmental messages on product packaging. We'll definitely be keeping tabs on their progress.

Interestingly, over six thousand miles away, a roundtable organised by the Energy Studies Institute at Singapore International Energy Week was taking place and grappling with the same topic of irrational behaviour. The speakers there challenged the way energy is described, discussed green envy and explored the implications of behavioural economics for energy policy. A short summary from the session is available here. It’s reassuring to see such growing global recognition for the role of psychology in making green choices.

The language of sustainability

Recent contact with organisations like ThinkFutureNow and Bristol Green Capital has certainly helped to crystallise PrimeDecision’s commitment to sustainability. But although our intention to run a green business feels strong and genuine, we are conscious of how vulnerable we all are to contextual influence. Surrounded by sustainability professionals at an event like Communicate, it is easy to be swept along by others’ commitment and enthusiasm. But in everyday life, sometimes the smallest things can deter or drive sustainable behaviour. To create meaningful change, we need to use these factors to our advantage – and be honest about how fallible we humans are.


We found a lovely example of how language can impact green behaviour when visiting Schumacher College. Naturally they place a lot of emphasis on recycling – and have a range of bins for cardboard, cartons, glass, aluminium, compost etc. Now although few people would disagree overtly with the idea of recycling, in the midst of a busy day it can often seem easier to use the general rubbish bin instead. Throwing rubbish into a bin is such a familiar and automatic action. Yet instead of calling it ‘general waste’ or ‘the bin’, Schumacher bluntly labels their bins: ‘Landfill’. Through simple reframing, it disrupts that familiar action and makes the environmental impact so much more apparent. It seemed to us a fantastic antidote for everyday laziness.

We don’t currently have evidence quantifying the impact of this particular change, or the means to encourage the spread of this practice. But it is important that we, and other organisations, take the time to do so. For although seemingly minor, these little cues can have a huge impact on our ability to adopt the sustainable behaviours that we wish for.