Psychologists usually have graduate education and hold a Ph.D. degree.
Human psychology attempts to measure development, change, normality, and abnormality. A psychologist is trained to make these comparative assessments and to apply principles of behavioral change to modify maladaptive behavior. There are various subspecialties within the field of psychology. Clinical psychologists have special training in various kinds of psychological diagnosis, assessment, and intervention. Child or educational psychologists assess the mental and emotional development of children, their intelligence, and social development.