Behaviour Change

PROPAGANDA FOR CHANGE is a project created by the students of Behaviour Change (ps359) and Professor Thomas Hills at the Psychology Department of the University of Warwick. This work was supported by funding from Warwick's Institute for Advanced Teaching and Learning.

Tuesday, March 1, 2016

5 Reasons to Eat 5 a Day

How often do you eat your recommended five portions of fruit and vegetables per day? My guess is not very often, so I’ve used a number of persuasive methods to try and convince you that healthy eating is not so bad!

Firstly, research has shown that those individuals who consume less fruit and veg tend to still eat similar portion sizes as high consumers, but just do so less often (Ashfield-Watt, Welch, Day, & Bingham, 2003). Therefore, the best way to up the intake of low consumers is to encourage them to eat more portions: and so the “5-a-day” message was born, and it's still shown to be the most effective.

We all care about our outward appearance, and research suggests that appearance-based interventions can be very effective at bringing about, and sustaining, behaviour chance (Stock et al., 2009). With other evidence that carotenoid coloration of the skin increases the appearance of health and attractiveness (from pigments in fruit and veg; Stephen, Coetzee & Perrett, 2010), it has been suggested that showing possible appearance improvements may suggest an immediate benefit from improving your diet (Whitehead, Ozakinci, Stephen, & Perrett, 2012). So, this ad gives you that tangible goal: the two women’s faces to the left of the ad represent a difference in daily fruit and veg consumption, and there’s definitely one with a healthier glow (that’s the one on the right – she eats her five a day!).

Most ads seem to include the image of an attractive woman to convince you to do something, and this one does too. When the targeted behaviour is related to appearance, seeing a physically attractive model makes the ad more effective: you assume they look so great because they do this thing, and so you want to do it too (Trampe, Stapel, Siero, & Mulder, 2010). This ad suggests that this slim, attractive model maintains her healthy weight and figure by eating her five portions of fruit a day – the only way to find out if this is true is to try it yourself!

Scare tactics also work wonderfully, so I’ve introduced the threat of several big, nasty illnesses that you might get by not eating healthily. This “fear appeal” makes you change your behaviour to protect yourself from the risks, as explained by the Protection Motivation Theory (Rogers, 1975): you see a threat, consider how likely it is to occur, and then, if a coping behaviour is available, you determine how easy it is to carry out that behaviour – if it’s easy, you’ll change your behaviour and avoid the risk without hesitation! So, this ad presents to you both a risk and an easy solution: eat your 5 a day and you won’t become horribly ill!

You might not know it, but research shows you're probably more influenced by uniformed figures; they appear to be an authority, so you’re more likely to comply to their wishes (Bickman, 2006). There’s also evidence that medical doctors are amongst the most trusted individuals when it comes to providing info about food-related risks (Frewer et al., 1996), so including the photo of a doctor makes you believe more in the statements presented, so you’re more likely to start eating your five a day.

So, there you go: five persuasion techniques to get you to eat your five a day. Maybe next time, you’ll reach for an apple instead of a chocolate bar.

Ashfield-Watt, P. A. L., Welch, A. A., Day, N. E., & Bingham, S. A. (2003). Is ‘five-a-day’ an effective way of increasing fruit and vegetable intakes? Public Health Nutrition, 7, 257-261.
Bickman, L. (2006). The social power of a uniform. Journal of Applied Social Psychology, 4, 47-61.
Dragsted, L. O., Krath, B., Ravn-Haren, G., Vogel, U. B., Vinggaard, A. M., Jensen, P. B., Loft, S., Rasmussen, S. E., Sandstrom, B., & Pedersen, A. (2006). Symposium on ‘phytochemicals’: Biological effects of fruit and vegetables. Proceedings of the Nutrition Society, 65, 61-67.
Frewer, L. J., Howard, C., Hedderley, D., & Shepherd, R. (1996). What determines trust in information about food-related risks? Underlying psychological constructs. Risk Analysis, 16, 473-486
National Stroke Association. (2014). Cholesterol and Stroke. Retrieved from:
NHS Choices. (2015). Why 5 A DAY? Retrieved from:
Rogers, R. W. (1975). A protection motivation theory of fear appeals and attitude change. The Journal of Psychology, 91, 93-114.
Stephen, I. D., Coetzee, V., & Perrett, D. I. (2010). Carotenoid and melanin pigment coloration affect perceived human health. Evolution and Human Behaviour, 32, 216-227.
Stock, M. L., Gerrard, M., Gibbons, F. X., Dykstra, J. L., Mahler, H. I. M., Walsh, L. A., & Kulik, J. A. (2009). Sun protection intervention for highway workers: Long-term efficacy of UV photography and skin cancer information on men’s protective cognitions and behaviour. Annals of Behavioural Medicine, 38, 225-236.
Trampe, D., Stapel, D. A., Siero, F. W., & Multer, H. (2010). Beauty as a tool: The effect of model attractiveness, product relevance, and elaboration likelihood on advertising effectiveness. Psychology & Marketing, 27, 1101-1121.
Whitehead, R. D., Ozakinci, G., Stephen, I. D., & Perrett, D. I. (2012). Appealing to vanity: Could potential appearance improvement motivate vegetable consumption? American Journal of Public Health, 102, 207-211.
Willetts, W. (1994). Diet and health: What should we eat? Science, 264, 532-537.

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