Babies at birth are not blank slates. Instead, they inherit a great deal of problem-solving equipment and arrive at many problems with solutions already at hand. Babies, helpless as they are, pop into the world with neural programs specialized for reasoning about objects, physical causality, numbers, the biological world, the beliefs and motivations of other individuals, and social interactions.
— David Eagleman, Incognito

Developmental Psychology: the branch of psychology concerned with change and development over the life span. (Cardwell, 74) The psychological, emotional, and perceptual changes that occur during a lifetime. (Collin, 260)

The science of human development seeks to understand how and why people - all kinds of people, everywhere - change or remain the same over time. (Berger, 3) Studies how people change physically, mentally, and socially. At every stage of life, developmental psychologists investigate the influence of multiple factors on development, including biological, environmental, social, cultural, and behavior factors. (Hockenbury, 351) Also referred to as ‘social development,’  ‘psychological development,’ and ‘life-span.’


Adolescent Development: changes in social interactions, most notably with parents and peers. Relationships with friends and peers become increasingly important. Social network, social context, and community influence values, norms, and expectations. Peer relationships tend to reinforce the traits and goals that parents fostered during childhood. (Hockenbury, 378)

Puberty: the stage of adolescence in which an individual reaches sexual maturity and becomes physiologically capable of sexual reproduction. (Hockenbury, 375)

Adult Development: according to Eric Erikson, the primary psychosocial task of early adulthood is to form a committed, mutually enhancing, intimate relationship with another person. During middle adulthood, it is to contribute to future generations through your children, your career, and other meaningful activities. (Hockenbury, 382)

Activity Theory of Aging: psychosocial theory that life satisfaction in late adulthood is highest when people maintain the level of activity they displayed earlier in life. (Hockenbury, 387)

Generativity: to contribute to future generations through your children, your career, and other meaningful activities. During middle adulthood, the primary “psychosocial” task becomes one of generativity. (Hockenbury, 382)

Epigenetic Theory: an emergent theory of development that considers both the genetic origins of behavior (within each person and within each species) and the direct, systematic influence that environmental forces have, over time, on genes. (Berger, 49)

Information Processing Model: the model that views cognitive development as a process that is continuous over the lifespan, and that studies the development of basic mental processes such as attention, memory, and problem solving. (Hockenbury, 373)

Psychosocial Development Theory: (Erik Erikson) proposed that each of eight stages of life is associated with a particular psychosocial conflict that can be resolved in either a positive or a negative direction. (Hockenbury, 380) Erikson's stages follow listed by age along with associated conflicts. (Hockenbury, 381)

Infancy: birth to 18 months. Conflict is “trust” vs. mistrust.

Toddlerhood: 18 months to 3 years. Conflict is “autonomy” vs. “doubt.”

Early Childhood: 3 to 6 years. Conflict is “initiative” vs. “guilt.”

Middle Childhood: 6 to 12 years. Conflict is 'industry' vs. 'inferiority.'

Adolescence: 12 to 18 years. Conflict is “identity” vs. 'role confusion.'

Young Adulthood: 18 to 40 years. Conflict is “intimacy” vs. 'isolation.'

Middle Adulthood: 40 to 65 years. Conflict is “generativity” vs. 'stagnation.'

Late Adulthood: 65 years plus. Conflict is ego 'integrity' vs. “despair.”

Sociocultural Theory: an emergent theory (of development) that holds that development results from the dynamic interaction between each person and the surrounding social and cultural forces. (Berger, 46)