developmental psychology
the branch of psychology that studies the changes—physical, mental, and behavioral—that occur from conception to old age and investigates the various biological, neurobiological, genetic, psychological, social, cultural, and environmental factors that affect development throughout the lifespan. Since its emergence as a formal discipline in the late 19th century, the field has broadened its focus from one that largely emphasized infant, child, and adolescent development to one, beginning in the 1920s, that also accounted for adult development and the aging process and, more recently, prenatal development. As such the term developmental psychology is now often considered virtually synonymous with lifespan developmental psychology. Over the years, numerous currents of thought and investigation have informed or shaped the field’s direction, such as the child study movement, psychoanalytic theory, learning theory, evolutionary
theory, the development of intelligence measures (e.g., Stanford–Binet Intelligence Scale), genetic studies, twin studies, research using longitudinal designs and cross-sectional designs, professional organizations and academic journals (e.g., Developmental Psychology, Psychology and Aging) devoted to understanding various aspects of the lifespan, and the explosion of brain research in recent decades. See also genetic psychology.