Psychology › Development & attachment
Lifespan development
· Concept
Well replicatedStrong, repeated evidence.
The view that people keep developing from birth to death, with gains and losses at every age.
See it on the Psychology map →What it says
Psychology once treated adults as finished products. In 1950 Erik Erikson mapped eight stages running into old age, and in 1987 Berlin psychologist Paul Baltes set out the 'lifespan' view: development is lifelong, runs in several directions at once, and depends on history and circumstance. Personality keeps changing: on average people grow more conscientious, agreeable and emotionally stable through middle age. Priorities shift too, toward fewer, closer relationships later in life.
Why it matters
It reframes careers, retirement and old age as stages with their own strengths and tasks, rather than a long plateau followed by decline.
The evidence
Status: well replicated. Studies that follow the same people for decades, such as the Harvard Study of Adult Development (since 1938) and the Seattle Longitudinal Study (since 1956).
Open questions
Whether happiness really dips in midlife, the so-called U-curve; results depend on methods, countries and statistical controls, and researchers disagree.
Inside this (4)
Connections (3)
▸Erikson's eight psychosocial stages are the classic map of Lifespan developmentMixed evidence
The connection
Erikson was among the first major theorists to treat development as lifelong. His eight stages run from infancy's trust versus mistrust to old age's integrity versus despair, with midlife centered on generativity, guiding the next generation rather than stagnating. The scheme gave later lifespan research its questions, even where the strict stage order did not hold.
Who showed it and when
Childhood and Society (1950), written in the US after Erikson's fieldwork with Lakota Sioux and Yurok communities and clinical practice in California.
How solid is it?
Many textbooks still organize lifespan development around his stages, and studies by Dan McAdams and others support generativity as a real midlife concern.
Open questions
Whether the stages unfold in a fixed order: many people revisit identity or intimacy at several ages as careers and families change.
▸Adolescence and the teenage brain is a pivotal phase of Lifespan developmentWell replicated
The connection
Adolescence is a second burst of brain and body change after early childhood. Puberty, peer focus, identity questions and new independence crowd into roughly ages 10 to 20. Habits and choices formed then, from schooling to health, shape adult life, and roughly half of lifetime mental-health conditions begin by age 18 (estimates vary).
Who showed it and when
G. Stanley Hall's 1904 book Adolescence founded the field; a 2018 Lancet paper proposed defining adolescence as ages 10 to 24.
The evidence
Long-running cohort studies, such as New Zealand's Dunedin study, link teen behavior and health to adult outcomes decades later.
Open questions
Where adolescence ends: later marriage, longer schooling and delayed home ownership blur the line, and experts disagree on stretching the definition.
▸Aging: what declines and what doesn't is the last chapter of Lifespan developmentWell replicated
The connection
Late adulthood is development too, with gains as well as losses. Processing speed and recall slow, but knowledge, vocabulary and emotional balance often hold or improve. Laura Carstensen's research finds older adults focus on fewer, more meaningful relationships and report fewer negative emotions. With longer lives, this chapter can now last 30 years or more.
Who showed it and when
Paul Baltes in Berlin argued from the 1980s that development continues through old age; Stanford's Laura Carstensen developed socioemotional selectivity theory in the 1990s.
The evidence
Long-term studies such as the Berlin Aging Study (from 1990) and the Seattle Longitudinal Study document gains alongside losses in the same people.
Open questions
Whether added years of life are mostly healthy years or years with illness; data from different countries and periods disagree.