Human Development

Abstract

Human development, which MeSH classifies under behavior and behavior mechanisms, is studied by life-span developmental psychology as constancy and change in behavior throughout the life course. This article covers life-span developmental theory and its account of growth and loss, the ecological and life-course contexts of development, the integration of nature and nurture, childhood self-control and its later correlates, adolescence and the proposed period of emerging adulthood, personality change and socioemotional goals in adulthood, the asynchronous rise and fall of cognitive abilities, brain growth charted across the life span, and the early onset of mental disorders. A recurring theme is that development continues throughout life and runs in more than one direction.

Keywords: life-span development, developmental psychology, life course, plasticity, aging

Life-span developmental psychology involves the study of constancy and change in behavior throughout the life course (Baltes, 1987). Issues raised by the pioneering longitudinal studies included the recognition that individual lives are influenced by their ever-changing historical context, and that concepts of human development should apply to processes across the life span (Elder, 1998).

What Human Development Is

Life-span research has advanced a metatheoretical view on the nature of development that includes multidirectionality in ontogenetic change, a focus on the dynamic and continuous interplay between growth (gain) and decline (loss), emphasis on historical embeddedness, and the study of the range of plasticity in development (Baltes, 1987). A later review outlined the general architecture of lifespan ontogeny, including its directionality and the age-differential allocation of developmental resources into three major goals of developmental adaptation: growth, maintenance and regulation of loss (Baltes et al., 1999).

Types of Human Development

MeSH places human development within behavior and behavior mechanisms and files two narrower descriptors beneath it, one for adolescence and one for childhood.

This is a classification for indexing literature, not a partition of developmental processes: the two subtypes are age periods, and MeSH files no separate descriptor here for adult development or aging. Child development does not have its own article on this site yet, so it appears without a link.

The Life-Span Perspective

One proposition of life-span theory is that any developmental change includes the joint occurrence of gain (growth) and loss (decline) in adaptive capacity (Baltes, 1987). The same account proposed that plasticity can best be studied with a research strategy called testing-the-limits (Baltes, 1987). A later meta-theory of development was based on the orchestrated and adaptive interplay between three processes of behavioral regulation: selection, optimization and compensation (Baltes et al., 1999).

Contexts of Development

An ecological approach to research in human development focuses on the progressive accommodation, throughout the life span, between the growing human organism and the changing environments in which it actually lives and grows (Bronfenbrenner, 1977). Those environments include not only the immediate settings containing the developing person but also the larger social contexts, both formal and informal, in which these settings are embedded (Bronfenbrenner, 1977).

The life-course perspective grew out of the pioneering longitudinal studies of child development, launched in the 1920s and 1930s, which eventually followed their young study members up to the middle years and later life (Elder, 1998). Life course theory has evolved since the 1960s through programmatic efforts to address the issues those studies raised (Elder, 1998); the site's article on the life course perspective covers it in detail.

Nature and Nurture

The understanding of nature and nurture within developmental science has evolved with alternating ascendance of one or the other as primary explanations for individual differences in life course trajectories (Sameroff, 2010). One response has been a dialectical perspective emphasizing the interconnectedness of individual and context, and a unified theory of development proposed to integrate personal change, context, regulation and representational models of development (Sameroff, 2010). Behavior-genetic research takes a different route: a meta-analysis of twin correlations and reported variance components for 17,804 traits from 2,748 publications, covering virtually all published twin studies of complex traits, found that across all traits the reported heritability is 49%, while noting that the relative importance and specific nature of the influences of genes and environment on human traits remain controversial (Polderman et al., 2015).

Childhood

Following a cohort of 1,000 children from birth to the age of 32 years, one study found that childhood self-control predicts physical health, substance dependence, personal finances and criminal offending outcomes, following a gradient of self-control (Moffitt et al., 2011). Effects of children's self-control could be disentangled from their intelligence and social class, and in another cohort of 500 sibling pairs the sibling with lower self-control had poorer outcomes despite shared family background (Moffitt et al., 2011). Trajectories of child cognitive development have also been described as determining the peak levels of adult cognitive function from which aging-related cognitive declines occur (Tucker-Drob, 2019).

Adolescence and Emerging Adulthood

Adolescence is the phase of life stretching between childhood and adulthood, and earlier puberty has accelerated its onset in nearly all populations while understanding of continued growth has lifted its endpoint age well into the 20s (Sawyer et al., 2018). Emerging adulthood has been proposed as a new conception of development for the period from the late teens through the twenties, with a focus on ages 18 to 25, and its proponent specified that it exists only in cultures that allow young people a prolonged period of independent role exploration (Arnett, 2000). Development across these years is covered under adolescent development. A critical examination of the concept found several limitations to the model and offered an alternative perspective that might complement the stage theory (Hendry & Kloep, 2007).

Adulthood and Aging

A meta-analysis of 92 samples found that people increase in measures of social dominance, conscientiousness and emotional stability, especially in young adulthood (age 20 to 40), and that 4 of 6 trait categories demonstrated significant change in middle and old age (Roberts et al., 2006). Socioemotional selectivity theory claims that the perception of time plays a fundamental role in the selection and pursuit of social goals: when time is perceived as open-ended, knowledge-related goals are prioritized, and when time is perceived as limited, emotional goals assume primacy (Carstensen et al., 1999). The authors also showed that the perception of time is malleable, and that social goals change in both younger and older people when time constraints are imposed (Carstensen et al., 1999).

Convergent evidence from 48,537 online participants and from normative data on standardized IQ and memory tests revealed considerable heterogeneity in when cognitive abilities peak: some abilities peak and begin to decline around high school graduation, some plateau in early adulthood and begin to decline in the 30s, and others do not peak until the 40s or later (Hartshorne & Germine, 2015). A review of cognitive aging emphasized person-to-person heterogeneity in trajectories of cognitive change over time, and how lifelong trajectories of cognitive function relate to the timing of the severe cognitive impairments characteristic of dementia (Tucker-Drob, 2019). Age-related cognitive change is covered further under cognitive aging.

The Brain Across the Life Span

Across four longitudinal samples spanning ages 8 to 30 years, cortical grey matter volume was at its highest in childhood, decreasing steadily through the second decade, while cerebral white matter volume increased until mid-to-late adolescence before decelerating (Mills et al., 2016). To provide reference standards comparable to growth charts for height and weight, one consortium aggregated 123,984 MRI scans, across more than 100 primary studies, from 101,457 human participants between 115 days post-conception and 100 years of age (Bethlehem et al., 2022). The resulting brain charts identified previously unreported neurodevelopmental milestones and showed high stability of individuals across longitudinal assessments (Bethlehem et al., 2022).

Mental Health Across the Life Span

In a nationally representative United States survey of 9,282 adults, the median age of onset was much earlier for anxiety (11 years) and impulse-control (11 years) disorders than for substance use (20 years) and mood (30 years) disorders, and half of all lifetime cases started by age 14 years and three fourths by age 24 years (Kessler et al., 2005). A later meta-analysis of 192 epidemiological studies (n = 708,561) reported that the proportions of individuals with onset of any mental disorder before the ages of 14, 18 and 25 were 34.6%, 48.4% and 62.5%, and that the peak age at onset was 14.5 years (Solmi et al., 2022).

Worked Example

The onset figures can be turned into intervals. If half of all lifetime cases start by age 14 years and three fourths by age 24 years (Kessler et al., 2005), then 75% - 50% = 25% of lifetime cases start in the ten years between those ages, and the remaining 100% - 75% = 25% start after age 24.

Discussion

The sources converge on development as lifelong: life-span developmental psychology studies constancy and change in behavior throughout the life course (Baltes, 1987), 4 of 6 personality trait categories demonstrated significant change in middle and old age (Roberts et al., 2006), and different cognitive abilities peak at different ages (Hartshorne & Germine, 2015). They also emphasize heterogeneity between people in trajectories of cognitive change (Tucker-Drob, 2019).

Current Directions

Brain charts have been described as an essential step towards robust quantification of individual variation benchmarked to normative trajectories in multiple neuroimaging phenotypes, built while acknowledging limitations due to known biases of MRI studies relative to the diversity of the global population (Bethlehem et al., 2022). A review of cognitive aging concluded that future research will benefit from accurately measuring and analyzing continuous variation in longitudinal trajectories of cognitive function (Tucker-Drob, 2019).

Common Misconceptions

Development ends when childhood ends.

Of 6 personality trait categories, 4 demonstrated significant change in middle and old age (Roberts et al., 2006).

All cognitive abilities peak at the same age.

Some abilities peak around high school graduation, some plateau in early adulthood and others do not peak until the 40s or later (Hartshorne & Germine, 2015).

Aging means only decline.

Life-span theory proposes that any developmental change includes the joint occurrence of gain and loss in adaptive capacity (Baltes, 1987).

Glossary

Adolescence.

The phase of life stretching between childhood and adulthood.

Brain charts.

Reference standards for brain morphology across the life span, analogous to growth charts for height and weight.

Emerging adulthood.

A proposed period of development from the late teens through the twenties, with a focus on ages 18 to 25, specified to exist only in cultures that allow young people a prolonged period of independent role exploration.

Gain and loss.

In life-span theory, the growth and decline in adaptive capacity proposed to occur jointly in any developmental change.

Historical embeddedness.

In life-span theory, the influence of historical and other structural contextual factors on development.

Life course theory.

A theory of development, evolved since the 1960s, holding that individual lives are influenced by their ever-changing historical context.

Life-span developmental psychology.

The study of constancy and change in behavior throughout the life course.

Mean-level change.

Change in the average level of a personality trait across the life course.

Multidirectionality.

In life-span theory, the recognition that ontogenetic change can run in more than one direction.

Plasticity.

In life-span theory, the range of possible change in development, proposed to be best studied by testing-the-limits.

Selection, optimization and compensation.

Three processes of behavioral regulation on whose interplay one meta-theory of life-span development is based.

Self-control.

In the cited cohort study, the childhood capacity whose gradient predicted later health, wealth and offending outcomes.

Socioemotional selectivity theory.

The theory that the perception of time plays a fundamental role in the selection and pursuit of social goals.

Testing-the-limits.

A research strategy proposed for studying plasticity in development.

Key Researchers

Jeffrey Jensen Arnett

. Psychologist at Clark University; proposed emerging adulthood as a period of development from the late teens through the twenties, specified to exist only in cultures that allow a prolonged period of independent role exploration. Wikidata - Wikipedia - Google Scholar - Faculty Page

Paul B. Baltes

(1939-2006). Psychologist and director of the Center of Lifespan Psychology at the Max Planck Institute for Human Development, Berlin; set out the theoretical propositions of life-span developmental psychology, including the joint occurrence of gain and loss. Wikidata - Wikipedia

Urie Bronfenbrenner

(1917-2005). Psychologist at Cornell University; proposed an experimental ecology of human development focused on the accommodation between the developing person and the changing environments in which it lives. Wikidata - Wikipedia - Faculty Page

Glen H. Elder

. Sociologist at the University of North Carolina at Chapel Hill (Carolina Population Center); set out the life course as developmental theory. Wikidata - Wikipedia - Faculty Page

Terrie E. Moffitt

. Psychologist at Duke University; led the cohort study showing that a gradient of childhood self-control predicts adult health, wealth and public safety. ORCID - Wikidata - Wikipedia - Google Scholar - Faculty Page

Brent W. Roberts

. Psychologist at the University of Illinois Urbana-Champaign; led the meta-analysis of mean-level change in personality traits across the life course. ORCID - Wikidata - Wikipedia - Google Scholar - Faculty Page

Frequently Asked Questions

What is life-span developmental psychology?

Life-span developmental psychology involves the study of constancy and change in behavior throughout the life course (Baltes, 1987).

Does development stop in adulthood?

A meta-analysis found that 4 of 6 personality trait categories demonstrated significant change in middle and old age (Roberts et al., 2006).

When do cognitive abilities peak?

Some abilities peak and begin to decline around high school graduation, some plateau in early adulthood, and others do not peak until the 40s or later (Hartshorne & Germine, 2015).

Does childhood self-control matter later in life?

In a cohort followed from birth to age 32 years, childhood self-control predicted physical health, substance dependence, personal finances and criminal offending outcomes (Moffitt et al., 2011).

What is the ecological approach to development?

It focuses on the progressive accommodation, throughout the life span, between the growing human organism and the changing environments in which it actually lives and grows (Bronfenbrenner, 1977).

Why do older adults prioritize emotional goals?

Socioemotional selectivity theory holds that when time is perceived as limited, emotional goals assume primacy (Carstensen et al., 1999).

When do mental disorders usually begin?

A meta-analysis of 192 epidemiological studies reported that 34.6% of individuals with any mental disorder had its onset before age 14, 48.4% before age 18 and 62.5% before age 25, with a peak age at onset of 14.5 years (Solmi et al., 2022).

How is brain development charted across the life span?

One consortium built brain charts from 123,984 MRI scans of 101,457 participants between 115 days post-conception and 100 years of age (Bethlehem et al., 2022).

References