Animal Intelligence is a consolidated record of Edward L. Thorndike's theoretical and empirical contributions to the comparative psychology of learning. Thorndike's approach is systematic and comprehensive experimentation using a variety of animals and tasks, all within a laboratory setting. When this book first appeared, it set a compelling example, and helped make the study of animal behavior very much an experimental laboratory science. This landmark study in the investigation of animal intelligence illustrates Thorndike's thinking on the evolution of the mind. It includes his formal statement of the influential law of effect, which had a significant impact on other behaviorists. Hull's law of primary reinforcement was closely related to the law of effect and Skinner acknowledged that the process of operant conditioning was probably that described in the law of effect.