Rationality, foraging, and associative learning : an integraltive approach

One basic requisite for rationality is that choices are consistent across situations. Animals commonly violate rationality premises as evidenced, for example, by context-dependent choices, and such apparent irrationalities stand as paradoxes that instigate re-examination of some assumptions in behaviour ecological modelling. The goal of the present thesis was to study the psychological mechanisms underlying apparent irrationalities in order to assess the functional implications of general processes of valuation and choice. A common thread through the different studies is the hypothesis that most animal 'irrationalities' are due to misinterpretation of what the optimum would be in natural circumstances, and hence of the maximised currency in the theoretical predictions. I believe that the trait that may have been of paramount influence in many organisms' selective history was the ability to learn about the predictability of events and their biological value, and that this is implemented in an overriding force of associative learning mechanisms. In chapters 2 and 3, I present evidence of context-dependent foraging choices in European starlings, Sturnus vulgaris, in the laboratory, and I implement a version of the Rescorla- Wagner learning model to account for both present data and apparent irrationalities reported by other authors. In chapter 4, I test the notion that context dependence may in fact be adaptive when animals face sequential choices, namely when they have to decide whether to take a prey item or to skip it in order to search for better alternatives. In chapter 5, I explore the functional implications of starlings' relative responding to incentives during an unexpected shortfall in reinforcement, and I also examine the extent to which information about the new environmental status helps them avoid energetic and time costs commonly seen in uninformed individuals. Last, in chapter 6, I present a brief summary of the main discussions considered and conclusions reached along this thesis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo