Endocrinology: the study of the endocrine system which secretes hormones into the bloodstream and regulates the body;
Neuroscience: the study of the central nervous system which uses neurons to coordinate our actions;
Economics: the study of the production, distribution and consumption of goods and services – crucial to the understanding of individuals in a fiercely capitalistic, free market society;
Psychology: the study of people and groups in order to best understand them;
Sociology, the study of a society in order to best understand that society and its inhabitants.
Needless to say that the role of some of the more social sciences on this list – particularly psychology – are already seen as having a role in successful user studies and understanding.
However, the preponderance of research and publications on user studies deal more with principals and practices of the discipline and less with understanding the users themselves, much less in a deep, multi-disciplinary scientific way. The future of design will belong to those who are able to untangle what people do and why, even those who can predict and understand – using a scientific basis – what people are likely to respond to and why and how, as opposed to simply making gut decisions.