Learning to Generalize through Predictive Representations: A Computational Model of Mediated Conditioning

Learning when and how to generalize knowledge from past experience to novel circumstances is a challenging problem many agents face. In animals, this generalization can be caused by mediated conditioning--when two stimuli gain a relationship through the mediation of a third stimulus. For example, in sensory preconditioning, if a light is always followed by a tone, and that tone is later paired with a shock, the light will come to elicit a fear reaction, even though the light was never directly paired with shock. In this paper, we present a computational model of mediated conditioning based on reinforcement learning with predictive representations. In the model, animals learn to predict future observations through the temporal-difference algorithm. These predictions are generated using both current observations and other predictions. The model was successfully applied to a range of animal learning phenomena, including sensory preconditioning, acquired equivalence, and mediated aversion. We suggest that animals and humans are fruitfully understood as representing their world as a set of chained predictions and propose that generalization in artificial agents may benefit from a similar approach.