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 12, 2018

Creating the illusion of empty shelves online

Have you ever heard “while stocks last” or “limited edition”? If you have, you have been subject to the marketing strategy of scarcity. This is a technique outlined in Commodity Theory. Commodity theory (Brock, 1968) addresses the notion of the effects caused by scarcity. The key idea is that the more unavailable some commodity is, the higher it will be valued. Many studies have found that this technique works in shopping choice situations, particularly if the product that is scarce is something we are attracted to (Verhallen, 1982).

This effect has often been shown in shelf-based studies where researchers have manipulated the amount of an item available in a real or perceived ‘shop’ (Van Herpen et al., 2009; Parker & Lehmann, 2011; Robinson et al., 2016). In modern times, with online shopping being the increasingly preferred option, marketers have had to take an alternative approach to create the illusion of scarcity. Take these examples from which I came across whilst I was searching for a hotel in Amsterdam:
The inclusion of fully booked hotels in the listings serves no other purpose than to promote feelings of scarcity in customers.  Claiming that “your dates are so popular” makes the customer feel that the reduced availability is due to popularity of the product. In Verhallen & Robben (1994) they found that participants preferred items that were unavailable due to popularity significantly more than those which were just accidentally unavailable. This would make this technique useful for encouraging customers to feel pressure to buy.

Everything about this listing lets you know that you definitely need to book very soon. As a “bestselling” property when you hover over it with your mouse, you are informed that ‘197 others have already booked this hotel today’. Whilst you have no information on how many rooms remain, just being informed that many rooms have been booked creates a feeling that there are not many left available (creating the illusion of scarcity). It also states that “travellers like you” are the ones that have booked up all these spaces which may include an element of social proof. Cialdini (2007) describes social proof as heuristic used to determine what is correct based on what others believe to be correct. Salmon et al., (2015) found that manipulating social proof in shopping situations (saying that a particular low-fat brand of cheese in the “most popular” or “best-selling) made shoppers significantly more likely to purchase the promoted option. This shows that just saying that other people like something can encourage others to make similar shopping choices (like in these ads).

It's clear that uses many of the persuasion methods we've discussed in class to try to convince customers that there's some urgency to buy. It has proven very effective in making this an exceptionally popular hotel booking website. I best hurry off before I miss out...


Brock, T. C. (1968). Implications of commodity theory for value change. In Psychological foundations of attitudes (pp. 243-275).
Cialdini, R. B. (2007). Influence: The psychology of persuasion (pp. 173-174). New York: Collins.
Parker, J. R., & Lehmann, D. R. (2011). When shelf-based scarcity impacts consumer preferences. Journal of Retailing87(2), 142-155.
Robinson, S. G., Brady, M. K., Lemon, K. N., & Giebelhausen, M. (2016). Less of this one? I'll take it: New insights on the influence of shelf-based scarcity. International Journal of Research in Marketing33(4), 961-965.
Salmon, S. J., De Vet, E., Adriaanse, M. A., Fennis, B. M., Veltkamp, M., & De Ridder, D. T. (2015). Social proof in the supermarket: Promoting healthy choices under low self-control conditions. Food quality and preference45, 113-120.
Van Herpen, E., Pieters, R., & Zeelenberg, M. (2009). When demand accelerates demand: Trailing the bandwagon. Journal of Consumer Psychology19(3), 302-312.
Verhallen, T. M. (1982). Scarcity and consumer choice behavior. Journal of Economic Psychology2(4), 299-322.
Verhallen, T. M., & Robben, H. S. (1994). Scarcity and preference: An experiment on unavailability and product evaluation. Journal of economic psychology15(2), 315-331.

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