Behaviorism may be most easily defined after contrasting it with other forms of psychology. Until the advent of behaviorism in 1912, all psychology was built upon a subject matter called consciousness or mind, as definitions of psychology show: James: Psychology is the description and explanation of states of consciousness as such. Angell: Psychology is commonly defined as the science of consciousness... Consciousness we can only define in terms of itself. Thorndike: Human psychology deals with the thoughts and feelings of human beings and seeks to explain the facts of intellect, character, and personal life. Seashore: Psychology is the science of mental health... the science of experience and behavior of the organism. Baldwin: We may define psychology as the science of the phenomena of consciousness