At the time of original publication psychobiology was one of the most rapidly developing areas of psychology. Its growth owed much to recent advances both in techniques for studying the physiological bases of behaviour and in major conceptual advances in the way people thought about the brain. First published in 1989, this textbook introduction to the field looks at the state of psychobiology in the light of these advances. The issues covered include: the factors that have shaped the current state of the field; the value of animal subjects in the study of psychological processes; the problems of studying the brain, including the theoretical assumptions underlying the most widely used methods; the current status of influential theories, like Stellar's 2-center theory of motivation and Papez's theory of emotion; the relationship between psychological theory and physiological data, such as recent accounts of the visual system; the problems presented by 'emergent properties' like consciousness.