It is customary in sociology to speak of modern and classical eras, but three eras need to be distinguished: a classical period running up to around 1920, an intermediate period extending to the 1960s, and a recent period, still continuing. Commerce between psychodynamic theory and sociology really begins in the intermediate, American era. American sociology underwent a distinctive evolution in the interwar years, with the shift from the Chicago School to functionalism. An important element in this is the separation of macro and microsociology. It should be noted that there is no debate between society and culture as governing concepts, as there is between British and American anthropology. Both macrosociology and microsociology are seen as the science of society: it is anthropology that is the science of culture. While the neo-Freudian theory appears to be increasingly sociological, it is sociological in terms of precisely the undifferentiated middle ground that sociology itself is in the process of abandoning.