Intransitive preferences in hoarding gray jays ( Perisoreus canadensis )

Abstract

Decision makers are often assumed to assign stable fitness-based values to foraging options. Under this assumption, the tendency to prefer the more valuable of two simultaneously available options should be transitive. For example, if option a is preferred when paired with b, and b is preferred when paired with c, then a should be preferred when paired with c. According to the principle of strong stochastic transitivity, the preference for a over c should be at least as strong as the stronger of the other two preferences (i.e., p(a,c)≥max[p(a,b), p(b,c)]). Gray jays (Perisoreus canadensis) collecting food for storage violated this principle, and failed to support even weaker forms of transitivity. All subjects preferred option a (one raisin, 28 cm into a tube) over b (two raisins, 42 cm), and b over c (three raisins, 56 cm), but none of the subjects preferred a over c. Such paradoxical preferences are often interpreted as evidence for simple heuristics rather than complex decision mechanisms. According to bounded rationality, intransitive choice is a suboptimal byproduct of heuristics that usually perform well in real-world situations. Alternatively, intransitive choice could be a byproduct of selection favoring a complex decision process involving context-dependent assessment of each the fitness-related value of each option. From this perspective, the decision maker's subjective valuation of each option is not fixed, but rather depends on the context (i.e., the specific pairing of options). In the experiment, the subjective value of option a was apparently lower in option set {a,c} than in {a,b}. A model of context-dependent choice is used to explore conditions under which adaptive choice based on a complex decision process can lead to intransitivity.