Psychology at Oxford is a scientific discipline, involving the rigorous formulation and testing of ideas. It works through experiments and systematic observation rather than introspection. Psychology has been defined as the science of mental life and its scope includes a wide variety of issues. It addresses such questions as: How do we perceive colours? How do children acquire language? What predisposes two people to get on with each other? What causes schizophrenia? The Oxford Experimental Psychology Department typically held four or five research seminars each week, in addition to undergraduate lectures and classes. At present, there are particularly strong research groups in the fields of human cognitive processes, neuroscience, language, developmental psychology, social psychology and psychological disorders.