Adult development is the study of changes and transitions that occur during adulthood, and includes theories in biology, psychology and sociology. The study of later adulthood also falls under the field entitled gerontology.
- 1 Adulthood
- 2 Metatheories
- 3 Biological approach
- 4 Stage theories
- 5 Gerotranscendence Theory
- 6 Aging-related decline
- 7 Studies
- 8 See also
- 9 External links
- 10 Notes
The concept of adulthood has legal and socio-cultural definitions. The legal definition of an adult is a person who has reached the age at which they are considered responsible for their own actions, and therefore legally accountable for them. This is referred to as the age of majority, which is age 18 in most cultures, although there is variation from 16 to 21.
The socio-cultural definition of being an adult is based on what a culture normatively views as being the required criteria for adulthood, which in turn influences the definitions of adulthood of individuals within that culture. This may or may not coincide with the legal definition. The theory of emerging adulthood suggests that individuals over the age of 18 in Western societies often do not feel adult, and others may not perceive them as adults. When asked, young adults often describe the importance of financial independence, living away from parents, entry into the workforce and a strong sense of responsibility as key indicators of full adulthood. These developmental markers are typically achieved by young adults in the West by their mid-twenties, which suggests that the socio-cultural definition and legal definitions of adulthood are not currently in sync. By the age of 25, the majority of young adults feel like an adult.
Changes that occur during adulthood can occur in many different ways, and correspondingly there a number of metatheories that act as frameworks for adult development research:
Mechanistic metatheory states that the source of developmental changes is the environment. These changes are continuous and smooth rather than step-like. Research is focused on examining the interactions of outside sources in shaping development, and the objects of study are observable and measurable. Within this framework, research involves quantitative designs. The chief criticisms of mechanistic metatheory center around the emphasis placed on external sources as the means of development, which disregards the individual differences.
Organismic metatheory states the source of developmental changes is a combination of biological changes and environmental forces. Developmental changes are viewed as qualitative and discontinuous, happening in spurts of growth or decline, where each stage is more complex than the last. Critics have pointed out that stages of development are not always numerical and do not necessarily occur in a linear order. Furthermore, some of these stages might not be found across different culture, and the happening of events that are outside the norm does not make those events abnormal.
Currently, contextual metatheory is the dominant philosophy in the study of adult development. Contextual theory synthetizes mechanistic and organismic philosophies, and acknowledges the influence of both biological (internal) and environmental (external) factor on developmental changes. Likewise, it also recognizes that development can happen in both continuous and discontinuous stages. Contextual metatheory takes into account individual differences, diversity, history and levels of culture.
The ‘biopsychosocial’ approach to adult development states that in order to understand human development in its fullness, biological, psychological and social levels of analysis must be included. There are a variety of biopsychosocial meta-models, but all entail a commitment to the following four premises:
- Human development happens concurrently at biological, psychological and social levels throughout life, and a full descriptive account of development must include all three levels.
- Development at each of these three levels reciprocally influences the other two levels; therefore nature (biology) and nurture (social environment) are in constant complex interaction, when considering how and why psychological development occurs.
- Biological, psychological and social descriptions and explanations are all as valid as each other, and no level has causal primacy over the other two.
- Any aspect of human development is best described and explained in relation to the whole person and their social context, as well as to their biological and cognitive-affective parts. This can be called a holistic or contextualist viewpoint, and can be contrasted with the reductionist approach to development, which tends to focus solely on biological or mechanistic explanations.
The biological approach focuses on physical changes and it is influenced by neuropsychology, biopsychology and behavioral neuroscience. It emphasizes the biological foundations of thoughts and behaviors, and how they relate to developmental changes.
Programmed theories argue that the aging process is paced and controlled by a biological timetable. The programmed longevity theory states that the loses and deficits that take place with aging are associated with different genes being turned off and on, whereas the endocrine theory shifts the focus away from genes to hormones as the chief controllers of the aging process and biological clock. A third theory, the immunological theory, places emphasis on the immune system, stating that it is programmed to decline overtime and therefore making the individual more vulnerable to disease and infections as aging progresses.
Error theories acknowledge the interactions between the environment and genetic factors, and how they influence aging. Under this paradigm, the wear and tear theory focus on how cell, tissues, organs, etc., deteriorate as time passes. The rate of living theory emphasizes resources and states that organisms die when the finite resources which sustain them are exhausted. Crosslinking theory frames the aging process at the molecular level, and claims that changes and reactions associated with negative aspects of aging take place when glucose molecules attach to proteins. The free radical theory instead emphasizes damage caused by “oxygen free radicals”. Lastly, the somatic DNA damage theory focuses on genetic mutations as the cause of cell deterioration over time.
Adult neurogenesis and neuroplasticity
An important finding in neuroscience for the study of adult development is that new neurons are constantly formed from stem cells in parts of the adult brain throughout adulthood, a process called adult neurogenesis. The hippocampus is the area of the brain that is most active in neurogenesis. Research shows that thousands of new neurons are produced in the hippocampus every day.
The brain also constantly changes and rewires itself throughout adulthood. This is referred to as neuroplasticity. Evidence suggests that the brain changes in response to diet, exercise, social environment, exercise, stress and toxin intake. These same external influences also influence genetic expression throughout adult life - a phenomenon known as genetic plasticity.
There are a variety of theories that posit specific stages through which adults pass as they develop<. Examples of some theories are Daniel Levinson’s theory of life's seasons, Lawrence Kohlberg's stages of moral development, and Erik Erikson’s stages of psychosocial development.
Daniel Levinson’s theory
Daniel Levinson’s theory aimed to establish a set of psychosocial 'seasons' through an adult must pass as they move through early adulthood and midlife. Each of these seasons is created by the challenges of building or maintaining a life structure, by the social norms that apply to particular age groups, particularly in relation to relationships and career. The process that underlies all these stages is individuation - a movement towards balance and wholeness over time. The key stages that he discerned in early adulthood and midlife were as follows:
- Early Adult Transition (Ages 16–24)
- Forming a Life Structure (Ages 24–28)
- Settling down (Ages 29–34)
- Becoming One’s Own Man (Ages 35–40)
- Midlife Transition (Early forties)
- Restabilization, into Late Adulthood (Age 45 and on)
Lawrence Kohlberg's stages of moral development
Lawrence Kohlberg focused on the individual’s moral judgment and the process toward moral maturity. His theory explains the ethic development of individuals through 6 stages of moral reasoning. He believed that each stage is essential and cannot be skipped, therefore everyone goes through every stage and progressively transitions to the next.
- Stage 1 – Obedience or Punishment Orientation
- Stage 2 – Self-Interest Orientation
- Stage 3 – Social Conformity Orientation
- Stage 4 – Law and Order Orientation
- Stage 5 – Social Contrast Orientation
- Stage 6 – Universal Ethics Orientation
Kohlberg's theory is a theory about moral progress; each stage is preferable to stage preceding it. Therefore it is a theory of positive adult development.
Erik Erikson’s theory
Erik Erikson developed stages of ego development that extended through childhood, adolescence and adulthood. He was trained in psychoanalysis and was highly influenced by Freud, but unlike Freud, Erikson believed that social interaction is very important in the individual’s psychosocial development. His stage theory consists of 8 stages in life from birth to old age, each of which is characterised by a tension within a specific dialectic. During each stage a particular dialectic is dominant, but it exists in all other age groups too. In between each stage their typically occurs a crisis, as a person moves from one existential concern to another.
- Stage 1 – Trust vs. Mistrust (0 to 1.5 yrs)
- Stage 2 – Autonomy vs. Shame and Doubt (1.5 – 3 years)
- Stage 3 – Initiative vs. Guilt (3 - 6 yrs)
- Stage 4 – Industry vs. Inferiority (6 years to puberty)
- Stage 5 – Identity vs. Role Confusion (adolescence)
- Stage 6 – Intimacy vs. Isolation (early adulthood)
- Stage 7 – Generativity vs. Stagnation (middle adulthood)
- Stage 8 – Integrity vs. Despair (late adulthood)
Gerotranscendence is referred to as the final stage in adult development in the natural progression towards maturity. Typically, during Gerotranscendence, an adult will redefine his or herself and their relationships with others. Individuals may also experience a decrease in interest in relation to material possessions and a greater need for “positive solitude” or internal reflection and meditation.
While there is much scope for growth in adulthood, from the age of 30, evidence of age-related decline is also present. This consists of cognitive and behavioral changes that range from poorer memory retrieval to worsening eyesight. Different theories and aspects regarding adult development are discussed below.
Illnesses associated with aging
As adult bodies undergo a variety of physical changes that cause health to decline, a higher risk of contracting a variety of illnesses, both physical and mental, is possible.
Dementia usually occurs within adults over the age of 65. This illness includes severe problems with reasoning, learning, and remembering experiences or thoughts. Dementia also sometimes causes the person to behave erratically and inappropriately. The most common form of dementia is Alzheimer's Disease. It is thought that neurodegenerative disease is one of the main causes for dementia, where neurons in the brain permanently lose function.
Scientists have made a distinctive connection between aging and cancer. It has been shown that the majority of cancer cases occur in those over 50 years of age. This may be due to the decline in strength of the immune system as one ages or co existing conditions. There a variety of symptoms associated with cancer, commonly growths or tumors may be indicators of cancer. Radiation, chemotherapy, and in some cases, surgery, is used to treat the cancer.
Arthritis is one of the most commonly experienced illnesses in adults as they age. Although there are a variety of types of arthritis they all include very similar symptoms: aching joints, stiff joints, continued joint pain, and problems moving joints.
It has been found that older age does increase the risk factor of contracting a cardiovascular disease. Hypertension and high cholesterol have also been found to increase the likelihood of acquiring a cardiovascular disease, which are also commonly found in older adults. Cardiovascular diseases include a variety of heart conditions that may induce a heart attack or other heart-related problems. Healthy eating, exercise, and avoiding smoking are usually used to prevent cardiovascular disease.
Infection occurs more easily as one ages, as the immune system starts to slow and become less effective. Aging also changes how the immune system reacts to infection, making new infections harder to detect and attack. Essentially, the immune system has a higher chance of being compromised the older one gets.
Studies are currently underway concerning adult development by Robert J. Waldinger and George Eman Vaillant at The Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School. Professor Robert J. Waldinger, from Boston Massachusetts, is studying a group of 724 men who have been a part of the study for 75 years. The study consists of two groups, the Grant Study, a group of men who attended Harvard University in 1938-1944 and the Glueck Study, a group of inner-city men from Boston. The intention is to examine early life predictors of healthy or unhealthy aging and relationships late in life. George E. Vaillant, who was the Director of the Study of Adult Development at the Harvard University Health Service for thirty five years has published this work in his books Adaptation to Life, 1977, The Wisdom of The Ego, 1993, and The Natural History of Alcoholism-Revisited, 1995. He charted adult development in 824 men and women their recovery process of schizophrenia, heroin addiction, alcoholism, and personality disorder.
Other known researchers in the field of adult development, and specifically ego development, are Jane Loevinger, William Torbert, Robert Kegan, Otto Laske and Susanne Cook-Greuter. Their developmental theories have a number of key traits in common. Specifically, they describe an unfolding of human potential, they maintain that growth occurs in a sequence of stages and that later stages are only reached by going through earlier stages, world views evolve from simple to complex, and that people's stage of development influences what they notice and can influence.
Adult development is a field that is relatively new and still is in need of a lot of research. Associations such as the Society for Research in Adult Development, strive to explore the subject and draw new findings. There are many areas in this field that could be further explored such as the process of aging, personality development, biological characteristics, mental disorders, and cultural differences in adult development.
- George Eman Vaillant
- Training and development
- Personal development
- Constructive Developmental Framework
- Laboratory of Adult Development 
- Journal of Adult Development 
- Psychology and Aging 
- Talent Development Resources! 
- National Center for the Study of Adult Learning and Literacy
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