Psychiatrists are medical doctors (MDs) who graduate from medical school, have a year of medical internship, and have 3 years of residency in the assessment and treatment of mental health disorders. Psychologists have a doctoral degree in an area of psychology, the study of the mind and human behavior. They’re not medical doctors. A psychologist can have a PhD in philosophy or a PsyD in clinical or counseling psychology. Typically, they do 1-2 years of internship. Unlike psychiatrists, psychologists are also trained in giving psychological tests (like IQ tests or personality tests).