Michael Lewis, PhD, is the University Distinguished Professor of Pediatrics and Psychiatry and Director of the Institute for the Study of Child Development at Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey. A widely cited leader in the field of developmental psychology, Dr. Lewis has written or edited more than 30 books. Jeannette M. Haviland-Jones, PhD, is Professor of Psychology and Director of the Human Emotions Lab at Rutgers, The State University of New Jersey. She has studied and written extensively about emotional development for over 25 years...