Abstract: | In two experiments, rats acquired brightness discriminations in a free-operant circular runway with two response alternatives. Both individual and group choice times revealed continuous changes that were not apparent in the discrete measure of choice. Two major assumptions of Spence's discrimination learning theory were confirmed: (a) learning is continuous, and (b) discriminative stimuli in simple discrimination tasks of both simultaneous and successive types are compounds with position elements as well as elements from the relevant visual dimension. The distinctive, consistent pattern of learning revealed by the choice-time measure suggests that position habits reflect a learning strategy in which the complex task is learned as a series of simpler ones. |