Behaviorism is the name given to several approaches to psychology, especially to the study of both animal and human learning, which arose in – and flourished during – the twentieth century. These approaches rejected the use of introspective methods (wherein individuals reported on their subjective experiences), and instead were based upon the study of behavior, its modification, and its observable antecedents and consequences – which were taken to be the only scientifically objective, publicly observable, sources of data. Consequently, behaviorists rejected characterizations of psychology that were given in terms of the study of mental events or of consciousness or “mind,” and instead defined psychology as the study of behavior and its modification. This focus, the behaviorists felt, brought unity to the psychological study of animals and humans.