Free food or earned food? A review and fuzzy model of contrafreeloading (1997)

Inglis, I. R., Forkmann, B., Lazarus, J.

Abstract

Unless they are quite hungry, animals of many species prefer to work for food rather than eat freely available food, a phenomenon known as contrafreeloading. "Animals will work (e.g. lever press) for `earned' food even though identical `free' food can easily be obtained from a nearby dish. .. Animals work for earned food in order to update their estimate of a currently sub-optimal food source because, in the longer term, it may unpredictably become the optimal place to feed. Contrafreeloading is therefore a behaviour that, under natural conditions, is adaptive" [p. 1171].