There is no evidence to suggest that there is any part of your brain that you do not use. Psychology study of behaviour (an attempt to describe, explain, predict, and change behaviour. ) Neuropsychology study of the relation between behaviour and the activity of the brain. Clinical neuropsychology branch of neuropsychology concerned with psychological assessment, management, and rehabilitation of neurological disease and injury. Heart, mind, and brain: the early history of neuropsychology. Empedocles: the heart was the source of human behaviour, known as the cardiac or cardio- centric hypothesis. Aristotle came to the same conclusion, and concluded that the heart was the source of thought and sensation. He argued that the brain served as a radiator, cooling the blood. Hippocrates and galen: the brain is responsible for the source of human behaviour, a view that is referred to as the cephalo-centric hypothesis or the brain hypothesis.