Behaviour Change

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

Thursday, March 3, 2016

Lemons: Lose weight and live longer

This advert uses several persuasion techniques to try to encourage people to drink lemon juice:

The first technique used is the 'that's-not-all technique'. The idea is that people will be tempted to try drinking lemon juice after hearing that it could help them to lose weight. They then find out it will also improve their health - suddenly it's a no brainer, they have to try lemon juice! The effectiveness of this technique has been demonstrated by Burger (1986). When people approached his stall to ask about the price of a cupcake they were either told it would be 75 cents for a cake and two cookies or they were told 75 cents for one cake before being informed by another sales person that the price now included two free cookies (that's-not-all). Almost twice as many participants bought the cupcake when the that's-not-all technique was used. This suggests that withholding information about the health benefits of lemon juice at first will make people more impressed by them later and therefore more likely to drink lemon juice. 

The second technique used in the advert uses the power of the messenger. Jenifer Aniston is seen smiling next to a statement that she uses lemon juice to lose weight. Research shows that using attractive women in adverts is effective - those shown an advert for sun-tan lotion rated the product more favorably after seeing an avert containing an attractive woman than an unattractive one (DeBono & Telesca, 1990). Attractive messengers don't just increase our liking of products; they also increase the likelihood that we will buy the product. Participants who heard a sales pitch for car insurance from an attractive male rated themselves as significantly more likely to purchase the insurance than those who heard the pitch from an unattractive male (DeShields, Kara & Kaynak, 1996). Therefore, the inclusion of Jenifer Aniston in the advert will increase the likelihood that people will go on to drink lemon juice.

Aside from being attractive, Jenifer Aniston is seen to be dressed in a white doctor's coat next to a quote saying lemon juice has been clinically proven to aid weight loss. The inclusion of the information that results are from clinical trials makes the information seem as though it is from a more credible source. We are more persuaded by information from a trustworthy and credible source than from a non-trustworthy source. For instance participants were more likely to believe an article about whether anti-histamine drugs should require a prescription if it was from the New England Journal of Biology and Medicine than from a general monthly magazine (Hovland & Weiss, 1951). Having Jenifer Aniston wear a white lab coat gives the impression that she is a doctor and therefore someone with authority and knowledge. People viewing the advert are much more likely to listen to the messenger and drink lemon juice when she is dressed as an authority figure as opposed to wearing normal clothes (Bushman, 1984). 


Burger, J. M. (1986). Increasing compliance by improving the deal: The that's-not-all technique. Journal of Personality and Social Psychology, 51, 277-283.

Bushman, B. J. (1984). Perceived symbols of authority and their influence on compliance. Journal of Applied Social Psychology, 14, 501-508.

Clay, W. D. (2004). Nutritional and health benefits of citrus fruits. C Economos, 24, 11-18.

DeBono, K. G., & Telesca, C. (1990). The influence of source physical attractiveness on advertising effectiveness: A functional perspective. Journal of Applied Social Psychology, 20, 1383-1395.

DeShields, O. W., Kara, A., & Kaynak, E. (1996). Source effects in purchase decisions: The impact of physical attractiveness and accent of salesperson. International Journal of Research in Marketing, 13, 89-101.

Hovland, C. I., & Weiss, W. (1951). The influence of source credibility on communication effectiveness. Public Opinion Quarterly, 15, 635-650.

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