The value of psychology as a science has been challenged in phenomenology and in other epistemological trends. The main objective of this book is to draw the attention of students of human and animal behaviour to important achievements in phenomenological psychology and comparative physiology which are mostly overlooked, although they offer a genuine approach to subjective experience in relation to behavioural regulations. The work of Brentano, Stumpf, Husserl, Politzer, Katz, Michotte, Buytendijk and many others is analysed from this epistemological standpoint. The significance of the phenomenological approach for the biology of behaviour is discussed. The meaning of Sherrington's physiology of the behavioural field is evaluated in the same framework. Basic reading for students of experimental psychology, comparative psychology and ethology, this book will appeal particularly to those interested in the philosophy of psychology and biology. Originally published in 1977.