The first systematic investigation of the problem of transfer of knowledge, in relation to economic decision-making. Transfer of knowledge plays an important, if all-too-often neglected, role in the determination of real world behaviour. For most economic situations are not identical to previous situations the agent has been faced with, and the dichotomy between perfect rationality and zero rationality - the belief that experience is irrelevant because anyway optimal play is chosen and the belief that it is irrelevant because agents do not store knowledge or cannot perceive similarity, and start every time afresh - is an implausible one.