Dr. Rudolph C. Hatfield, PhD is a retired clinical neuropsychologist who specialized in assessing and treating neurological and psychiatric disorders. His areas of expertise include neurobiology, behavior, dementia, head injury, addiction, abnormal psychology, personality disorders, statistics, rehabilitation psychology, and research methodology. Dr. Harfield currently writes about human behavior, the brain, and research methods for various mental health websites. He has also authored two books: "The Everything Guide to the Human Brain: Journey Through the Parts of the Brain, Discover How It Works, and Improve Your Brain's Health" (2013), and "The Everything Guide to Coping with Panic Disorder: Learn How to Take Control of Your Panic and Live a Healthier, Happier Life" (2013).