Background context and decision making in hoarding gray jays

If decision makers assign stable fitness-related values to options, preference for the most valuable of simultaneously encountered options should be independent of background context (i.e., prior options). The tendency to choose option x versus y should be unaffected by whether the decision maker has already been given a choice between x and y or between x and y . Here, food-hoarding gray jays (Perisoreus canadensis) were given an initial choice between x (one raisin, 0.5 m into a tube) and y (three raisins, 0.5 m) or between x and y (both identical to x ). All subjects were then given a choice between x (one raisin, 0.3 m) and y (three raisins, 0.7 m). In violation of the principle of irrelevant alternatives, the ‘‘market share’’ of x depended on prior options. Subjects initially exposed to context {x , y } showed a stronger preference for x than did subjects initially exposed to {x , y }, which implies that the jays did not assign a fixed value to each option. Subjects that initially could obtain a large reward (y ) for about the same ‘‘price’’ (perceived danger) as a small reward (x ) apparently devalued the large reward (y) in the subsequent choice. This effect may be the joint byproduct of cognitive constraints and an adaptive tendency to use information provided by the context.