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.

Monday, March 11, 2013

Final sales

Often on the streets we will see shops with posters saying ‘final sale, further reductions while stock lasts and don't miss out on it’. These posters are designed to persuade people into coming into their shop and purchase their product. 

A study by Worchel, Lee, and Adewole (1975) showed that scarce products are more highly valued than products with plentiful availability. In their experiment, a jar of chocolate chip cookies was presented to participants and they were required to taste a cookie and rate its quality. They manipulated the scarcity of the product by changing the number of cookies within a jar; the jar contained either two (scarce) or ten (not scarce) identical cookies. As predicted by the commodity theory, participants rated the scarce cookies (two cookies in a jar) as more desirable to eat and more costly than the non-scarce cookies (ten in a jar). 

Another study by Tversky and Kahneman (1991)  showed that losses and disadvantages have greater impact on preferences than gains and advantages, this is known as the principle of loss aversion. 

In the poster, the sentence ‘while stock lasts’ uses the commodity theory and attracts customers because they are emphasizing that their products and in low availability. Furthermore, the sentence ‘don’t miss out on it’ highlights that if we do not enter the shop, we will lose an opportunity to buy their product with a discounted price. 


Tversky, A. & Kahneman, D. (1991). Loss Aversion in Riskless Choice: A Reference Dependent Model. Quarterly Journal of Economics, 106, 1039-1061.

Worchel, S., Lee, J., & Adewole, A. (1975). Effects of supply and demand on ratings of object value. Journal of Personality and Social Psychology, 32, 906-914.

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