<P> The 20th century saw a rejection of Freud's theories as being too unscientific, and a reaction against Edward Titchener's atomistic approach of the mind . This led to the formulation of behaviorism by John B. Watson, which was popularized by B.F. Skinner . Behaviorism proposed epistemologically limiting psychological study to overt behavior, since that could be reliably measured . Scientific knowledge of the "mind" was considered too metaphysical, hence impossible to achieve . </P> <P> The final decades of the 20th century have seen the rise of a new interdisciplinary approach to studying human psychology, known collectively as cognitive science . Cognitive science again considers the mind as a subject for investigation, using the tools of psychology, linguistics, computer science, philosophy, and neurobiology . New methods of visualizing the activity of the brain, such as PET scans and CAT scans, began to exert their influence as well, leading some researchers to investigate the mind by investigating the brain, rather than cognition . These new forms of investigation assume that a wide understanding of the human mind is possible, and that such an understanding may be applied to other research domains, such as artificial intelligence . </P> <P> Ibn Khaldun can be regarded as the earliest scientific systematic sociologist . The modern sociology, emerged in the early 19th century as the academic response to the modernization of the world . Among many early sociologists (e.g., Émile Durkheim), the aim of sociology was in structuralism, understanding the cohesion of social groups, and developing an "antidote" to social disintegration . Max Weber was concerned with the modernization of society through the concept of rationalization, which he believed would trap individuals in an "iron cage" of rational thought . Some sociologists, including Georg Simmel and W.E.B. Du Bois, utilized more microsociological, qualitative analyses . This microlevel approach played an important role in American sociology, with the theories of George Herbert Mead and his student Herbert Blumer resulting in the creation of the symbolic interactionism approach to sociology . </P> <P> American sociology in the 1940s and 1950s was dominated largely by Talcott Parsons, who argued that aspects of society that promoted structural integration were therefore "functional". This structural functionalism approach was questioned in the 1960s, when sociologists came to see this approach as merely a justification for inequalities present in the status quo . In reaction, conflict theory was developed, which was based in part on the philosophies of Karl Marx . Conflict theorists saw society as an arena in which different groups compete for control over resources . Symbolic interactionism also came to be regarded as central to sociological thinking . Erving Goffman saw social interactions as a stage performance, with individuals preparing "backstage" and attempting to control their audience through impression management . While these theories are currently prominent in sociological thought, other approaches exist, including feminist theory, post-structuralism, rational choice theory, and postmodernism . </P>

When did social sciences began to divide into distinct areas of research