Psychology differs from anthropology, economics, political science, and sociology in seeking to capture explanatory generalizations about the mental function and overt behaviour of individuals, while the other disciplines focus on creating descriptive generalizations about the functioning of social groups or situation-specific human behaviour. In practice, however, there is quite a lot of cross-fertilization that takes place among the various fields. Psychology differs from biology and neuroscience in that it is primarily concerned with the interaction of mental processes and behaviour, and of the overall processes of a system, and not simply the biological or neural processes themselves, though the subfield of neuropsychology combines the study of the actual neural processes with the study of the mental effects they have subjectively produced.