Behaviourism

A school of psychology that studies behavior and argues that all human actions are learned responses to environmental stimuli, not innate traits.

From behaviour (from Old French avoir, from Latin habere meaning 'to have' or 'to hold,' evolving to mean 'how one holds oneself' or 'conducts oneself') + -ism (from Greek -ismos, suffix for systems or doctrines). Behaviourism as a formal philosophy emerged in early 20th-century psychology.