Final answer:
Dr. Schmitt's field of interest is developmental psychology, which is the scientific study of development across a lifespan, focusing on changes in thoughts, physical abilities, and social connections.
Step-by-step explanation:
Dr. Schmitt's field of interest is developmental psychology. Developmental psychology is the scientific study of development across a lifespan. Developmental psychologists are interested in the changes people experience throughout their lifetimes, including thoughts, physical abilities, and social connections.