of measuring political techniques using psychological theories. The entry of the US into World War II spiraled vast research into fields such as war technique, propaganda, group moral, psycho-biography and culture conflict to name a few, with the U.S. army and Navy recruiting young psychologists. Thus the discipline quickly developed and gained international accreditation. Hadley Cantril and L. A. Free established the Institute for International Social Research to focus "attention primarily on psychological changes which influence political behavior in ways that have significant effect on international relations." They studied "governments and why, in terms of psychological variables, they behave as they do in regard to international issues." McGuire identifies three broad phases in the development of political psychology, these three phases are: (1) The era of personality studies in the 1940s and 1950s dominated by psychoanalysis. (2) The era of political attitudes and voting behavior studies in the 1960s and 1970s characterized by the popularity of "rational man" assumptions. (3) An era since the 1980s and 1990s, which has focused on political beliefs, information processing and decision making, and has dealt in particular with international politics. Personality and politics The study of personality in political psychology focuses on the effects of leadership personality on decision-making, and the consequences of mass personality on leadership boundaries. Key personality approaches utilized in political psychology are psychoanalytic theories, trait-based theories and motive-based theories. A psychoanalytical approach Sigmund Freud (1856–1939) made significant contributions to the study of personality in political psychology through his theories on the unconscious motives of behavior. Freud suggested that a leader's behavior and decision making skill were largely determined by the interaction in their personality of the id, ego and superego, and their control of the pleasure principle and reality principle. The psychoanalytic approach has also been used extensively in psychobiographies of political leaders. Psychobiographies draw inferences from personal, social and political development, starting from childhood, to understand behavior patterns that can be implemented to predict decision-making motives and strategies. A trait-based approach Traits are personality characteristics that show to be stable over time and in different situations, creating predispositions to perceive and respond in particular ways. Gordon Allport (1897–1967) realized the study of traits introducing central, secondary, cardinal and common traits. These four distinctions suggest that people demonstrate traits to varying degrees, and further that there is a difference between individual and common traits to be recognized within a society.