Science Interviews

Interview

Sat, 8th Sep 2012

Improving our diets with the right kind of information

Julia Allan

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Chris -   Now we’ve all been there.  It’s the end of a very long day.  You're tired and hungry, and you know you shouldn’t but you're finding the lure of the cake counter impossible to resist.  Now scientists think that this sort of willpower failure is responsible for many of us putting on weight.  Thankfully, Aberdeen Psychologist Julia Allan has come to the rescue.

MenuJulia -   What we were particularly interested in is why people don’t stick to their good dietary intentions.  So we know that a lot of health promotion campaigns focus around giving people information, under the assumption that if you give people more information, they’ll make a better choice.  So, an example would be the 5-a-day campaign.  We’re telling people, "you should eat 5 a day," we’re telling people the benefits of 5 a day, and we’re assuming at some level that having that information will make them more likely to eat 5-a-day.  But, unfortunately, what we know and what's now very well established is that information on its own isn’t sufficient to produce behaviour change.  So, we’ve been developing little signs to be displayed at food order points in coffee shops, and the signs show the entire range of snack foods that are available, ordered from on the left hand side the least calorific, up to the most calorific on the right hand side.  And they have a little message at the top saying, “If you want to eat fewer calories today then choose one of the snacks on the left.”  And so, we’re directing people’s attention away from the higher calorie snacks and towards the lower calorie ones.

Chris -   That would be sort of Mars bar over on the right, banana on the left; and so, you're saying to people, “You can have one of those or one of those.  And if you want fewer calories, go to the left hand end of the scale.”

 Julia -   Yes and we’re trying to capitalise on people’s natural slight bias for the left side of visual space, so people will naturally pay slightly more attention to things presented on the left than the right.

 Chris -   Does it work?

 Julia -   When we’ve been testing these, we randomly allocate coffee shops in blocks of a week.  So, we’ll have the sign randomly displayed for 6 weeks out of a 12-week period and then we’ll record sales figures throughout the entire period and compare sales of all the different items when the signs are there and when the signs are not.  And what we’re seeing is that, when the signs are present, we see a measurable reduction in sales of all of the higher calorie items and about half of the lower calorie items increase their sales. So people do seem to be switching down and making different dietary decisions.

Chris -   So, it clearly works because people were changing their behaviour.  How did it go down with the store owners though, because if they're not selling a Mars bar and they're selling an apple instead, that’s okay; but if they sell no Mars bar and someone doesn’t buy something instead, they're going to lose money...

Julia -   I think that’s always a tricky issue and we did have a lot of negotiations at the start of this project about whether or not we could trial an intervention that ultimately might negatively impact on their sales.  But I think there's been a real shift in the culture of organisations towards promoting healthy eating, so many of these places now have a healthy living award, and so on.  So, they were actually fairly open to the idea.  The beauty of this intervention is, more typically, people were switching one purchase for another.  So, some people certainly didn’t buy things, but a more typical pattern was to see how many calories were in – for example a latte - and to choose to have a black coffee instead.

Chris -   Did you quiz any customers who had interacted with the sign and then bought something so that you could see how they reacted to it?  What was their perspective?

Julia -   Yes, we did.  We had about 130 customers who agreed to come and be interviewed after the study, and we went away and we measured their executive function [willpower], and we found that the people with the weakest executive function were much more likely than others to have changed their behaviour in response to the sign.  People were buying fewer calories than they would typically buy during a visit to that coffee shop.  And when we asked them how they’d use the sign, most had used it in the way that we’d expected or had not used it at all.  They had either not noticed it or not felt it was relevant. But we did have a sizeable minority who used the sign in a way where we hadn’t anticipated.  They would see, for example, that there were 300 calories in their milky coffee and decide that they could have 3 "Milky Ways" [chocolate bars] instead of that - and that’s exactly what they did!

 Chris -   So, they were buying stuff which was actually not necessarily a healthier option, but they knew they could get away with this many bad things in place of one coffee, so they were trading one evil for another...

Julia -   Yes, there was a sizeable minority that did exactly that and I have to say, anecdotally, they were all women.  So, they’ve made the decision based on, it seemed to us that, “Oh well, I would’ve had that anyway and look, I could have 3 small bars of chocolate for the cost of that coffee,” which was not really what we intend.  So, it’s a work in progress.

Chris -   Will this translate to other things?  You’ve done it with food.  What about fizzy drinks or maybe other things?  Could it work with cigarettes?  Could you have nicotine and tar levels or something on a similar sort of scale and persuade people to switch to a less unhealthy cigarette?

Julia -   Well, we’ve done it initially in snack foods and we’ve also done it in drinks because we know that the kind of premium coffee industry is also a big source of calories.  So I think a lot of people don’t realise when they're in Starbucks that there's up to a 500-calorie difference between a full fat hot chocolate and a black coffee.  And so, we’ve got the same effect in drinks, but there's a general principle, so in theory it should apply to any behaviour that requires willpower or self-regulation.

Chris -   I'm going to have to knock the lattes on the head.  That was Julia Allan. And the results of her study show that people tended to eat, on average, 66 fewer calories as a result of her intervention and that is sufficient, other studies have shown, to make a meaningful dent in a person’s likelihood of gaining weight.

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