As humans, we seem to have an innate disposition to collect things, be it stamps, antiques or some of the slightly stranger collections seen here! And when it comes to collecting things, the rarer they are, more often than not, the more we want them. This can be explained simply by the scarcity principle, whereby when things have limited availability, they become more desirable to us. We see them as having a higher quality just because they are rarer.
Commodity theory (Brock, 1968), explains the influence of scarcity with its principle claim being that any commodity will be valued to the extent that it is unavailable. An interesting example of this is shown in a study by Zellinger, Fromkin, Speller & Kohn (1975). In this study, they looked to see if age restrictions on pornographic material would increase desire to look at it as predicted by the commodity theory.
To test this, 64 male undergraduates were given a booklet containing statements allegedly from a book cover. Half received an age restriction statement, while the other half did not. Also, half were told the book was definitely pornographic whilst half did not. Subjects then completed a questionnaire with rating scales for their valuation of the book. Commodity theory would predict that placing age restrictions on the material would make it more desirable and therefore participants would value it higher.
Results confirmed this prediction, showing that when age restrictions were in place, the desire to read the book, liking of the book and desirableness of the book increased. The implications of these results are not just confirmatory to the scarcity principle and commodity theory, but they also highlight a social issue. Legal attempts to decrease the consumption of pornographic materials may have an unanticipated opposite psychological effect to the original intent. This means governmental attempts at preventing children from accessing porn may in fact lead to them looking at it.
The authors go on to highlight potential future areas for research by looking at this effect on pornographic stimuli such as magazines, films and photographs. In addition, they note that their study used only male participants and so it could not be assumed that this same effect will be had on females.
Brock, T. C. (1968). Implications of commodity theory for value change. In A. G. Greenwald, T. C. Brock,
& T. M. Ostrom (Eds.), Psychological foundations of attitudes (pp. 243- 275). New York:
Zellinger, D. A., Fromkin, H. L., Speller, D. E., & Kohn, C. A. (1975). Commodity theory analysis of the
effects of age restrictions upon pornographic materials. Journal of Applied Psychology, 60, 94-