Theoretical Developments in the Psychology of Aging

Copyright 1996 byThe Gerontological Society of America

The CerontologistVol. 36, No. 6, 742-748

This article presents a summary overview of the most distinctive psychological theories ofaging since World War I I . Theoretical developments are broadly classified into three

periods, respectively: The Classical period ('40s-'70s), represented by DevelopmentalTasks/Activity Theory, Psychosocial Theory of Personality Development, Counterpart

Theory, Disengagement/Activity Theory, Personality Theory of Age and Aging, andCognitive Theory of Personality and Aging; the Modern period ('70s-'90s), which includestheories on Life-span Development and Aging, Reduced Processing Resources, Personality

and Aging, Behavioral Genetics and Aging; and the New period ('80s—'90s), represented byGerotranscendence and Gerodynamics/Branching Theory. The overview ends with an

outlook on psychogerontological theorizing.Key Words: Psychological theories of aging, Gerodynamics, Branching theory,

Gerotranscendence

Theoretical Developmentsin the Psychology of Aging

Johannes J. F. Schroots, PhD1

The scientific history of the psychology of aging isquite brief (Birren, 1961). Aside from pioneer work byG. S. Hall (1922), Charlotte Buhler (1933), Carl G. Jung(1933), and Walter Miles (1933), theoretical develop-ments in psychogerontology started basically afterWorld War II. Since then, research in the psychologyof aging has been guided by a somewhat diversecollection of theories, models, and metaphors, ofwhich the time-based, gerontological research ap-proach is by far the most important (Schroots &Birren, 1990). From a calendar time perspective thereare three foci — the aged, age, and aging (see alsoTreas & Passuth, 1988). The first, the psychology ofthe aged, focuses on older people and later life.Grounded in a stages-of-life perspective, most stud-ies of the aged demonstrate a thematic, descriptiveapproach and little coherence (e.g., studies of Alz-heimer's disease, life satisfaction, widowhood, re-tirement, cognition, death and dying). The secondapproach in psychogerontology falls within the psy-chology of age, which studies age differences inbehavior by comparing groups of different ages incross-sectional research. Productive research fo-cuses on identifying the causes and consequences ofthe processes responsible for age-related differ-ences (e.g., processing speed, attentional capacity,etc.). Finally, the psychology of aging studies behav-ioral patterns of change with age, integrating boththe psychology of age and the aged in longitudinalresearch.

After World War 11 theoretical developments in thesubject matter can be broadly classified into threegroups or periods: the Classical period ('40s-70s),

1Address correspondence to Johannes J. F. Schroots, PhD, ERGO/European Research Institute on Health and Aging, University of Amster-dam, Roetersstraat 15,1018 WB Amsterdam, The Netherlands.

the Modern period (70s-'90s), and the New period('80s-'90s; Schroots, 1996). From each group themost distinctive psychological theories of aging arerepresented in Table 1. Before summarizing thesetheories, with the emphasis on Modern and Newtheories, some general issues in gerontological theo-rizing need to be discussed.

Some Issues

The first issue concerns the distinction betweenthe terms theory, model, and metaphor. Accordingto Lewin (1951), there is nothing so practical as agood theory. A theoretical framework helps the sci-entist to accumulate and integrate data into a body ofknowledge, as well as to provide directions for newresearch. Early attempts to develop formal, quantita-tive theories in the behavioral and social scienceshave not been very successful. The attention of re-searchers was turned, therefore, to the formalizationof models, which are regarded to be more simpleand quantifiable than theories, but also focus onlimited aspects of behavior. Formalization in terms ofquantitative models (or theories, for that matter),ignores the constructivist view that science is in anessential way metaphorical or characteristically em-ploys metaphors. In fact, models are extended andsystematic metaphors. This explains why the termstheory, model, and metaphor are often used inter-changeably in the research literature (Schroots, Bir-ren, & Kenyon, 1991). The relative significance ofthese terms can be summarized as follows: the meta-phor drives the theory in the psychology of aging inthe first place, and the model functions as a moregeneral, extended or systematic kind of metaphor,which connects theory with empirical research. Inthe following sections, the term "theory" should beunderstood in the broadest sense of the word.

742 The Gerontologist

Downloaded from https://academic.oup.com/gerontologist/article-abstract/36/6/742/567063by gueston 14 February 2018

Table 1. Schematic Overview of Psychological Theories of Aging

Theory Author(s)

Classical TheoriesDevelopmental Tasks/Activity TheoryPsychosocial Theory of Personality DevelopmentCounterpart TheoryDisengagement/Activity TheoryPersonality Theory of Age and AgingCognitive Theory of Personality and Aging

Modern TheoriesLife-span Development and AgingReduced Processing ResourcesPersonality and AgingBehavioral Genetics and Aging

New TheoriesCerotranscendenceCerodynamics/Branching Theory

Havighurst (1948)Erikson (1950)Birren (1960)Cumming & Henry (1961)Neugarten (1968)Thomae (1970)

Baltes et al. (1980,1987,1992)Salthouse (1985,1988,1991)Erikson (1950); Levinson (1978); Costa & McCrae (1988,1992)Plomin & McClearn (1990); Pedersen (1996)

Tornstam (1989,1992,1994)Schroots (1988,1995a, b)

The second issue concerns the term "aging."Briefly summarized, the psychology of aging studiesthe regular changes in behavior after young adult-hood (Birren & Renner, 1977). Thus defined, thepsychology of aging is grounded in a two-stages-of-life perspective, development and aging, which areusually described as two successive processes ofchange in time, with the transition point or apex atmaturity. The classic metaphor for the two stages ofage-related change in life is the "h i l l " metaphor(Hall, 1922), which is based on biological concep-tions of growth and decline, particularly, the so-called mortality curve: mortality rates are high forinfants, regularly decline to a minimum at about age10, and then rise progressively throughout the re-mainder of the life span (Gompertz' law, 1825). Psy-chological processes of change, however, do notnecessarily parallel biological changes along the life-span. For example, fluid abilities like speed of infor-mation processing reflect genetic-biological deter-minants and tend to decline with age. Crystallizedabilities, on the other hand, represent social-culturalinfluences on general world knowledge, for exam-ple, and may display some growth with age (Horn,1989). This cognitive phenomenon raises the as yetunsolved problem of to what extent psychologicalprocesses of development and aging are differentfrom each other, as both processes refer to age-related changes.

The third, also unresolved issue is what changesare typical or normal psychological processes ofchange in the individual, and what changes are atypi-cal, abnormal, or pathological patterns. The bounda-ries between these phenomena are often indistinct.To clarify this issue, Busse (1969) made a conceptualdistinction between primary and secondary aging.Primary aging refers to changes intrinsic to the agingprocess that are ultimately irreversible. Secondaryaging refers to changes caused by illnesses that arecorrelated with age but may be reversible or prevent-able. Later, a third distinction was added, tertiaryaging, which refers to changes that occur precipi-tously in old age (Birren & Cunningham, 1985, p. 22).

In the following overview, the term aging should beunderstood as primary aging.

The fourth and last issue concerns the term "psy-chological." Psychology as a science has laboriousrelations with the adjacent biological and social sci-ences. Sometimes, psychological theories of agingare labeled as "psychosocial" (with the emphasis on"social"); at other times they are conceived as biobe-havioral, behavioral genetic, or neuropsychological,with the emphasis on the biological substrate. Ineither case, the aging individual falls into the trap ofbiological or social reductionism. But also within thefield of psychogerontology there is the question ofreductionism, because of the unidirectional empha-sis on cognition and information processing, to theneglect of affective and conative processes of changeover the life span. Obviously, the psychology ofaging is in a permanent identity crisis. As Birren andLanum (1991, p. 114-115) would say,

There is no major theory or underlying metaphor thatlinks the various areas of psychology. Its state is muchlike physics was in the first decades of this century inwhich there was little unifying theory that linked thetopics of optics, sound, levers, heat, and light. Con-temporary psychology has similar topical islands ofknowledge organized under the headings of sensa-tion and perception, memory, learning, psycholin-guistics, social psychology, motor skills, psychome-trics, and developmental psychology. It is notsurprising that the psychology of aging takes on acomplexion derived from these subdivisions.

The following overview aptly illustrates Birren andLanum's point.

Classical Theories

Developmental Tasks/Activity Theory. — In 1948Robert J. Havighurst published his often reprintedbook on the concept of developmental tasks in a life-span perspective. A developmental task arises at orabout a certain period in the life of the individual,successful achievement of which leads to his happi-ness and success with later tasks, while failure leads

Vol.36, No. 6,1996 743


to unhappiness in the individual, disapproval by thesociety, and difficulty with later tasks. All of thesetasks have biological (physical maturation), psycho-logical (aspiration or values), and cultural (expecta-tions of society) bases. Havighurst has described sixdevelopmental stages or age periods in total, eachwith its own developmental task. Later on, the cen-tral organizing concept of age-related developmen-tal tasks has been named "activity theory," as op-posed to "disengagement theory."

Psychosocial Theory of Personality Development.— In 1950 Erik Erikson formulated a psychosocialtheory of eight stages of personality development,each with its own characteristic crisis that arises outof the conflict between two opposite tendencies.The developmental task of each age period is toresolve its conflict, which requires the integration ofpersonal needs with the demands of society. Thesuccessful resolution of each conflict leads to devel-opmental strength in terms of a new virtue. Failure,however, to deal adequately with a task during itsperiod of ascendancy is damaging to personality de-velopment. Erikson's psychosocial stages of devel-opment are not tied closely to specific age periods.The early stages are defined in much more detail thanthe later ones: postadolescence, for example, in-cludes about three quarters of the life span, but onlythe last three stages. This division reflects the in-crease in psychosocial variability with age: the devel-opmental tasks of an infant are relatively universal,but the tasks in later life are dependent as much onpersonal experiences as on general principles.

Counterpart Theory. — In 1960 James E. Birrenpresented a general theory of aging as a counterpartof development. The term "counterpart" is meant toexpress the idea that there are latent structures ofbehavior (emotions, cognition, and motivations) car-ried forward from earlier experience that interactwith present situations. Counterpart theory advo-cates indirect selection for positive late-life charac-teristics that embrace a wide range of complex bio-logical (e.g., potential for a long life) and behavioral(e.g., intelligence) characteristics. For example, al-though individual differences in longevity do notappear until long after reproduction has been com-pleted, intelligent, long-lived parents are able toprovide an environment (in terms of food and pro-tection) favorable for their young to survive. Birren'scounterpart theory expanded the classical "h i l l " met-aphor of development and aging to include ques-tions about their relationships and how behaviorcomes to be organized over the adult years of life, ifnot over the whole life span.

Disengagement/Activity Theory. — The term "dis-engagement" refers to the withdrawal of people fromprevious roles or activities. Starting from the assump-tion that people turn inward from middle age andover, Cumming and Henry theorized in 1961 that thisprimary mental process produces: (a) a natural andnormal withdrawal from social roles and activities,

and (b) an increasing preoccupation with self anddecreasing emotional involvement with others. Al-though the disengagement theory professes to ex-plain general psychological and social processes ofaging, it offers in fact a one-sided view of the aged,given the significant proportion of older people whodo not lose interest in life and do not withdraw fromsociety. Disengagement theory encouraged the de-velopment of an opposing theory of the aged, activitytheory, which is based on the concept of develop-mental tasks. According to its main proponent, Ro-bert J. Havighurst, activity theory states that in orderto maintain a positive sense of self, elderly personsmust substitute new roles for those lost in old age. Assuch, activity theory presents a more realistic view ofolder people.

Personality Theory of Age and Aging. — Starting inthe 1950s, Bernice L. Neugarten (1968) and associatesstudied the life cycle with two theoretical emphases.The first emphasis is on the timing of transitionalevents in the lives and roles of individuals. Lifeevents, such as marriage or parenthood, are norma-tively scheduled: that is, they are expected to occurwithin certain ages and in a certain sequence. Assuch, they lead to changes in self-concept and iden-tity. However, unexpected events (e.g., accidents) orage-normative events that occur "off t ime" (e.g.,early widowhood) may have negative developmentalconsequences, such as life crises. The second em-phasis is on the study of personality type as predictorfor successful aging. Aging is viewed as a process ofadaptation in which personality is the key element.Eight different patterns of aging have been distin-guished. The successfully aging individual not onlyplays an active role in adapting to the biological andsocial changes that occur with the passage of time,but also in creating patterns of life that will give himor her greatest ego involvement and life satisfaction.

Cognitive Theory of Personality and Aging. — In1970 Hans Thomae described briefly a cognitive the-ory of the aging personality, one which is intended tointegrate various biological, sociological, and interac-tionist perspectives while at the same time focusingupon the psychodynamics of aging. Central conceptsin his theory are those of perception, perceived situa-tion, and perceived self. Thomae postulates, for ex-ample, that perceived change rather than objectivechange is related to behavioral change, and thatchange is perceived and evaluated in terms of theaging person's dominant concerns and expectations.Successful adaptation to age-related changes, then,relates to the maintenance and restructuring of thebalance between cognitive and motivational systems;for instance, the balance between acceptance of one-self as old or rejection of this perception, which is oneof the developmental tasks of aging persons.

Modern Theories

Life-span Development and Aging. — Since thebeginning of the 1980s, Paul B. Baltes and his associ-



ates (Baltes, 1987; Baltes, Reese, & Lipsitt, 1980;Baltes, Smith, & Staudinger, 1992) have conducted aseries of studies on psychological processes of de-velopment and aging from a life-span perspective. Inline with the tradition of life-span developmentalpsychology, development and aging are conceivedas synonyms for behavioral changes across the lifespan. Starting from these studies, Baltes has devel-oped a theoretical framework of seven propositionsabout the nature of human aging from a psychologi-cal point of view: (1) there are major differencesbetween normal, pathological, and optimal aging,the latter defined as aging under development-enhancing and age-friendly environmental condi-tions; (2) the course of aging shows much inter-individual variability (heterogeneity); (3) there ismuch latent reserve capacity in old age; (4) there isaging loss in the range of reserve capacity or adaptiv-ity; (5) individual and social knowledge (crystallizedintelligence) enriches the mind and can compensatefor age-related decline in fluid intelligence (aginglosses); (6) with age, the balance between gains andlosses becomes increasingly negative; and finally, (7)the self in old age remains a resilient system ofcoping and maintaining integrity.

Based on this framework of propositions, a psy-chological model of successful aging has been de-vised, called "selective optimization with compensa-t ion." The central focus of this model is on themanagement of the dynamics between gains andlosses, i.e., a general process of adaptation, consist-ing of three interacting elements. First, there is theelement of selection, which refers to an increasingrestriction of one's life to fewer domains of function-ing because of an age-related loss in the range ofadaptive potential. The second element, optimiza-tion, reflects the view that people engage in behav-iors to enrich and augment their general reservesand to maximize their chosen life courses (and asso-ciated forms of behavior) with regard to quantity andquality. The third element, compensation, resultsalso (like selection) from restrictions in the range ofadaptive potential. It becomes operative when spe-cific behavioral capacities are lost or are reducedbelow a standard required for adequate functioning.

The lifelong process of selective optimization withcompensation allows people to age successfully, i.e.,to engage in life tasks that are important to themdespite a reduction in energy. For instance, the fa-mous pianist Rubinstein remarked in a televisioninterview that he conquers the weaknesses of aging(adaptation) in his piano playing in the followingmanner: First, he reduces his repertoire and plays asmaller number of pieces (selection); second, hepractices these more often (optimization); and third,he slows down his speed of playing prior to fastmovements, thereby producing a contrast that en-hances the impression of speed in the fast move-ments (compensation).

Reduced Processing Resources. — For some time,it has been generally accepted that there is an aver-age age-related decline in cognitive performance.

Researchers have advanced several explanations forthis phenomenon of aging, but so far only theresource-reduction view has found wide support. Inthis view, aging leads to a reduction in the quantity ofone or more processing resources, such as atten-tional capacity, working memory capacity or speedof processing. According to Timothy A. Salthouse(1985, 1988, 1991) — a typical exponent of this viewsince the eighties — processing resources are char-acterized by three properties: (1) they are limited inquantity, with a measurable aspect such as quantityor effectiveness of allocation increasing up until ma-turity and then decreasing across the adult years; (2)they enable or enhance cognitive processing so thatperformance in many cognitive tasks is improvedwhen greater amounts of the resources are available;and (3) they are not local or specific in the sense thatthey are restricted to a small number of highly similarcognitive tasks, but instead are relevant to a broadrange of cognitive processes.

The three properties of processing resources havegenerated a number of specific theories. They can beclassified into three categories, based on the domi-nant metaphor used in theorizing on resource-reduction, i.e., metaphors of space, energy, and/ortime. That is, space limitations correspond to restric-tions on the size of the computational or workingmemory region available for processing; energy limi-tations correspond to attentional capacity restric-tions; and time limitations refer to restrictions im-posed by tradeoffs between the rate at whichinformation can be processed and the rate at which itbecomes unavailable through decay, interference orsome other mechanism.

In a series of experimental studies, Salthouse andhis associates have focused on the time metaphor ofprocessing speed as explanatory construct of cogni-tive aging. Their findings indicate that processingspeed is a fundamental construct in human cogni-tion, linked to explicit changes in neural structureand functioning on the one hand and to higher-ordercognitive processes like reasoning and abstractionon the other. As such, Salthouse hypothesizes thatprocessing speed may well provide the cornerstonefor integrative theories of cognitive aging. It shouldbe noted, however, that the resource-reduction viewleaves unanswered the fundamental questions ofwhy the reduction in resources occurs, and how thatreduction results in lower levels of cognitive perfor-mance (for a review, see Birren & Fisher, 1995).

Personality and Aging. — Studies of personalityand aging reflect the concept of personality behindthem, here defined as the set of characteristic dispo-sitions that determine emotional, interpersonal, ex-periential, attitudinal, and motivational styles. Gen-erally speaking, two theoretical traditions can bedistinguished in this field, trait and developmental-stage models. In both traditions, the central issueconcerns the extent and nature of personality stabil-ity and change over the life span; or, to put it differ-ently, the extent to which aging processes per se areresponsible for personality change.

Vol. 36, No. 6,1996 745


Theoretical models of adult personality develop-ment represent the first and oldest tradition in thepersonality-and-aging field. Two theories, devel-oped by Erik Erikson (1950) and Daniel Levinson(1978), respectively, offer developmental stages be-yond the period of early adulthood. Erikson's eightstages, extending from infancy to old age, were for-mulated more than 45 years ago. From this perspec-tive, it is surprising that there has been collected onlylimited empirical evidence for the maturity and old-age stages, i.e., generativity vs stagnation and integ-rity vs despair. There are no longitudinal studies, forexample, that ask whether the achievement ofgenerativity in midlife is a necessary precursor forthe achievement of integrity in the later years. InLevinson's theory of personality development, basedon a series of in-depth interviews with 40 men, eachman's life structure goes through an orderly se-quence of three periods: early adulthood, middleadulthood, and late adulthood. The timing andlength of each period and the development thattakes place within it vary from man to man depend-ing on the biological, psychological, and social con-ditions of his life. Nevertheless, a close linkage ofperiods with age intervals is suggested. Levinson'stheory can be severely criticized on many grounds,of which the impossibility of replicating the in-depthinterviews poses the most serious problem in agingresearch.

Trait models represent the second tradition. Over-all, longitudinal studies of personality traits have con-sistently found structural invariance of personalityover time, i.e., a marked pattern of similarity in factorstructure across instruments, cohorts, types andtimes of measurement. According to Paul Costa andRobert McCrae (1988,1992) — typical proponents ofthe trait model—the same five major factors (neuroti-cism, extroversion, openness to experience, agree-ableness, and conscientiousness) have emerged fromlongitudinal studies using somewhat different ap-proaches. In conclusion of the evidence, they statethat people stay much the same in their basic disposi-tions and show a high degree of stability of personal-ity, particularly during the latter half of their lifecourse. More recent extensions of the trait modelpertain to personality-linked constructs like locus ofcontrol and self-concept. Generalizations about sta-bility and change are limited by the relatively smallnumber of studies available, the large majority ofwhich are cross-sectional in design. However, there isa growing consensus that personality traits tend to bestable with age whereas key aspects of self such asgoals, values, coping styles and control beliefs aremore amenable to change (for a review, see Ruth &Coleman, 1996).

Behavioral Genetics and Aging. — Behavioralgeneticists of aging are concerned with the extentto which hereditary factors influence age-relatedchanges over the life span of the individual. Here,heritability is defined as a descriptive statistic refer-ring to the portion of observed, phenotypic variationin the population that can be accounted for by ge-

netic differences among individuals; the rest of thevariation, the nongenetic portion, is called environ-mental. Thus, change in heritability over the life spanindicates that the relative roles of genetic and envi-ronmental influences can change with age in termsof their effects on biological and behavioral differ-ences among individuals in the population.

Robert Plomin and Gerald E. McClearn (1990), twoleading researchers since the eighties, have convinc-ingly shown that behavioral genetics provides a the-ory and methods that can go beyond simple nature-nurture comparisons to consider age differences,age changes, shared and nonshared environments,and multivariate analyses. Nevertheless, theory for-mation in gerontological behavioral genetics is still inits infancy. On the basis of recent analyses of mostlytwin studies of aging, the third leading researcher inthis field, Nancy L. Pedersen (1996), comes to thefollowing tentative conclusion: (a) the relative im-portance of genetic and environmental effects onindividual differences in the elderly is phenotype-specific. Heritability is low to moderate for personal-ity traits and measures of well-being, moderate forhealth-related phenotypes, and greater for cognitiveabilities, whereas heritability for memory is lowerthan for verbal and spatial abilities or perceptualspeed; (b) there are age differences in heritability,the pattern of which is phenotype-dependent. Forsome measures, particularly health-related charac-teristics, the relative importance of genetic effectsappears to decrease across age groups. For others,heritability is stable, increases, or reflects an invertedL-shaped function. Variance changes may reflect ei-ther an increase in environmental or genetic influ-ences, depending on the phenotype. More often,environmental effects account for the increase invariability in health-related phenotypes; (c) acrossshort spans of time, genetic effects are more stablethan environmental effects for personality and cogni-tion. Environmental effects of importance for indi-vidual differences late in life are changing. Neverthe-less, environmental influences are at least asimportant for phenotypic stability across short (3-6-year) spans of time.

New Theories

Gerotranscendence. — In 1989 Lars Tornstam sug-gested that human aging, the very process of livinginto old age, encompasses a general potential to-wards gerotranscendence; that is, a shift in meta-perspective from a materialistic and rational vision toa more cosmic and transcendent one, normally fol-lowed by an increase in life satisfaction. On the basisof qualitative and quantitative studies, Tornstam(1992, 1994) developed the theoretical concept ofgerotranscendence at three levels of age-related on-tological change: (1) cosmic level — changes in theperception of time, space and objects, increase ofaffinity with past and coming generations, changes inthe perception of life, disappearing fear of death,acceptance of the mystery dimension in life, andincrease of cosmic communion with the spirit of the



universe; (2) self — discovery of hidden (both goodand bad) aspects of the self, decrease of self-centeredness, self-transcendence from egoism to al-truism, rediscovery of the child within, and ego-integrity; (3) social and individual relations — lessinterest in superficial relations, increasing need forsolitude, more understanding of the difference be-tween self and role, decreasing interest in materialthings, and increase of reflection.

The new theory of gerotranscendence remindsone of the classical concepts of disengagement(Cumming & Henry, 1961) and integrity (Erikson,1950), but differs qualitatively in some opposite as-pects. For example, gerotranscendence implies a"redefinition of reality," while disengagement is re-stricted to "turning inwards"; also, gerotranscen-dence is connected with "social activity" and a needfor solitary "philosophizing" at the same time, whiledisengagement encompasses social withdrawal only.Cerotranscendence refers to offensive, multi-copingstrategies, while disengagement implies defensivecoping strategies and social breakdown. Finally,Erikson's integrity refers primarily to the integrationof elements in a life that have passed, while gero-transcendence implies more of a forward or outwarddirection, including the redefinition of reality. Sum-marizing, even though Tornstam's theory of gero-transcendence is based on limited empirical evi-dence, it nevertheless makes a promising attempt tointegrate and further develop some classical andmodern psychosocial theories of aging.

Gerodynamicsi'Branching Theory. — Recently, theauthor (Schroots, 1995a, 1995b) presented a brief out-line of a dynamic systems theory of aging, calledgerodynamics. This theory at its inception, whichelaborates his 1988 essay, is based on general systemstheory, notably the 2nd law of thermodynamics, anddynamic systems theory (chaos theory). The 2nd lawstates that there is an increase of entropy or disorderwith age in living systems, resulting in the system'sdeath. Chaos theory postulates that internal or exter-nal fluctuations of dynamic, far-from-equilibrium sys-tems can pass a critical point — the transformationpoint — and create order out of disorder through aprocess of self-organization, that is, a process bywhich a structure or pattern of change emerges withthe passage of time. From this metatheoretical view-point, the aging of living systems can be conceived asa nonlinear series of transformations into higher and/or lower order structures or processes, showing aprogressive trend toward more disorder than orderover the life span, and resulting in the system's death.

Cerodynamics lies at the root of a new aspecttheory of aging, called branching theory. The basicprinciple of this theory is the bifurcation or branch-ing behavior of the individual at the biological, psy-chological or social level of functioning. Metaphori-cally speaking, bifurcation means that the fluctuatingindividual (organism) passes a critical point — thebifurcation, branching or transformation point —and can branch off into higher and/or lower orderstructures or processes. Higher and lower order

structures can be translated in terms of mortality(probability of dying, life expectancy), morbidity(disease, disorder, disability or dysfunction) andquality of life (well-being, life satisfaction). For exam-ple, traumatic life events and a healthy life style mayresult in lower and higher order structures, respec-tively, and consequently in higher and lower proba-bilities of dying. It should be noted, however, thatlower order bifurcations at the biological or psycho-logical level of functioning (e.g., illness or divorce)do not always result in lower order branching behav-ior. Some people, for instance, are strengthened byillness, and divorce may have a positive rather than anegative effect on mental health in terms of lifeexpectancy and quality of life.

Briefly summarized, branching theory studies thedeterminants and patterns of branching behavioracross the life span. As yet, this innovative theory ofaging is not based on empirical evidence. It remainsto be seen how empirical research in progress lendssupport to its theoretical claims.

Next Ten Years

Owing to circumstances, a schematic overview ofpostwar psychological theories of aging was lackingin Emergent Theories of Aging (Birren & Bengtson,1988). Hopefully, the foregoing supplies a need,even though this overview illustrates painfully Bir-ren's classic dictum that the field of psychogeronto-logy is data-rich but theory-poor. The question ariseshow psychogerontological theorizing will look tenyears from now. Extrapolation of the section on NewTheories teaches that two types of theoretical devel-opments can be expected (see also Birren &Schroots, 1996).

The first development is taking place at the inter-section of science and the humanities, and relates tointeresting combinations of qualitative and quantita-tive research (Denzin & Lincoln, 1994). The roots ofqualitative research lie in the traditional soil of idio-graphic methods and techniques for the study ofindividual lives. In its modern form, qualitative re-search on aging is partly a reaction to what has beenomitted in quantitative research, i.e., the experi-ences of growing old and being old. In this respect,personal life narratives are rediscovered as a richsource of new insights into the experience of humanaging. Increasingly, life stories (e.g., letters, diaries,autobiographies, interviews) are being used for awide range of research studies on topics of psycho-logical importance (Birren, Kenyon, Ruth, Schroots,& Svensson, 1996). This development will no doubtbe stimulated by the recent publication of sophisti-cated software packages for the qualitative and quan-titative analysis of non-numerical, unstructured, bio-graphical data (e.g., QSR NUD*IST [Richards &Richards, 1995] and WINMAX Pro [Kuckartz, 1996]).

The second development is concerned with thetheoretical expansion of what has been called gero-dynamics and the derived branching theory of aging.Increasingly, the study of aging depends on longi-tudinal and time-series data to gain insights intothe branching patterns and processes of change.

Vol. 36, No. 6,1996 747


Findings suggest that there is a wide range of individ-ual differences in the rate and manner of aging at alllevels of analysis — biological, psychological, andsocial (Schroots, 1993). From a methodological per-spective, considerable progress has been made incharacterizing the time-varying distributions associ-ated with aging (e.g., longitudinal factor analysis,latent growth curve analysis, state-space modeling).Methodological sophistication, however, is inmarked contrast with the verbal form of most psy-chological theories of aging (Charness, 1995; Mole-naar, 1993). For this reason, the primary task of thenext ten years is to search for ways to integratetheoretical thought and empirical research. A prom-ising approach consists of dynamic systems model-ing — that is, on the basis of time-series data, anindividual is characterized by a set of parametervalues and a history of events that shape his or herparticular aging (growth) trajectory. ParaphrasingVan Geert (1994, p. 277), who advocates a so-calledexperimental theoretical developmental psychology,mathematical model-building is necessary to peelthe psychological theories of aging out of the verbalform in which they have been caught. Once thedynamic theory or model is expressed in a set ofequations, it is possible to try out the model under asmany conditions as possible. The Latin origin of theword "experiment" is "the act of trying," and it is inthis sense that the study of the behavior of dynamicmodels is a form of the experimental theoreticalpsychology of aging that promotes the integration ofdata and theory in the future.

References

Baltes, P. B. (1987). Theoretical propositions of life-span developmentalpsychology: On the dynamics between growth and decline. Develop-mental Psychology, 23, 611-626.

Baltes, P. B., Reese, H. W., & Lipsitt, L. P. (1980). Life-span developmentalpsychology. Annual Review of Psychology, 31, 65-110.

Baltes, P. B., Smith, J., & Staudinger, U. M. (1992). Wisdom and successfulaging. In T. B. Sonderegger (Ed.), Nebraska symposium on motivation:Psychology and aging. Lincoln, NE: University of Nebraska Press.

Birren, J. E. (1960). Behavioral theories of aging. In N. W. Shock (Ed.), Aging:Some social and biological aspects. Washington, DC: American Associ-ation for the Advancement of Science.

Birren, J. E. (1961). A brief history of the psychology of aging. The Cerontol-ogist, 7,69-77,127-134.

Birren, J. E.,& Bengtson, V. L. (1988). Emergent theories of aging. New York:Springer.

Birren, J. E., & Cunningham, W. R. (1985). Research on the psychology ofaging: Principles, concepts and theory. In J. E. Birren & K. W. Schaie(Eds.), Handbook of the psychology of aging (2nd ed.). New York: VanNostrand Reinhold.

Birren,). E., & Fisher, L. M. (1995). Aging and speed of behavior: Possibleconsequences for psychological functioning. Annual Review of Psy-chology, 46, 329-353.

Birren, J. E., Kenyon, C. M., Ruth, J. E., Schroots, J. J. F., & Svensson, T.(Eds.). (1996). Aging and biography: Explorations in adult development.New York: Springer.

Birren, J. E., & Lanum, J. C. (1991). Metaphors of psychology and aging. InC. M. Kenyon, J. E. Birren, & J. J. F. Schroots (Eds.), Metaphors of agingin science and the humanities. New York: Springer.

Birren, ). E., & Renner, V. J. (1977). Research on the psychology of aging:Principles and experimentation. In J. E. Birren & K. W. Schaie (Eds.),Handbook of the psychology of aging. New York: Van NostrandReinhold.

Birren, J. E., & Schroots, J. J. F. (1996). History, concepts, and theory in thepsychology of aging. In J. E. Birren & K. W. Schaie (Eds.), Handbook ofthe psychology of aging (4th ed.). San Diego: Academic Press.

Buhler, C. (1933). Der menschliche Lebenslauf als psychologisches Prob-lem. Leipzig, Germany: Hirzel.

Busse, E. W. (1969). Theories of aging. In E. W. Busse & E. Pfeiffer (Eds.),Behavior and adaptation in late life. Boston, MA: Little, Brown.

Charness, N. (1995). Psychological models of aging: How, who, and what? Acomment. Canadian journal on Aging, 14, 67-73.

Costa, P. T., & McCrae, R. R. (1988). Personality in adulthood: A six-yearlongitudinal study of self-reports and spouse ratings on the NEO Per-sonality Inventory. Journal of Personality and Social Psychology, 54,853-863.

Costa, P. T., & McCrae, R. R. (1992). Trait psychology comes of age. In T. B.Sonderegger (Ed.), Nebraska symposium on motivation: Psychologyand aging. Lincoln, NE: University of Nebraska Press.

Cumming, E., & Henry, W. E. (1961). Crowing old. New York: Basic Books.Denzin, N. K., & Lincoln, Y. S. (Eds.). (1994). Handbook of qualitative

research. Thousand Oaks, CA: Sage.Erikson, E. H. (1950). Childhood and society. New York: W. W. Norton.Gompertz, B. (1825). On the nature of the function expressive of the law of

human mortality. Philosophical Transactions of the Royal Society ofLondon, 1, 513-585.

Hall, G. S. (1922). Senescence: The last half of life. New York: Appleton.Havighurst, R. J. (1948). Developmental tasks and education. New York:

McKay.Horn, J. L. (1989). Models of intelligence. In R. Linn (Ed.), Intelligence:

Measurement, theory and public policy. Urbana, IL: University ofIllinois.

Jung, C. G. (1933). Modern man in search of a soul. New York: Harvest.Kuckartz, U. (1996). WINMAX Pro. Berlin: BSS/Freie Universitat.Levinson, D. J. (1978). The seasons of a man's life. New York: KnopfLewin, K. (1951). Field theory in social science. New York: Harper.Miles, W. R. (1933). Age and human ability. Psychological Review, 40,

99-123.Molenaar, P. C. M. (1993). Some innovatory methodological aspects of

longitudinal studies of health and aging. In J. J. F. Schroots (Ed.), Aging,health and competence: The next generation of longitudinal research.Amsterdam: Elsevier Science Publishers.

Neugarten, B. L. (Ed.). (1968). Middle age and aging. Chicago: University ofChicago Press.

Pedersen, N. L. (1996). Gerontological behavior genetics. In J. E. Birren & K.W. Schaie (Eds.), Handbook of the psychology of aging (4th ed.). SanDiego, CA: Academic Press.

Plomin, R., & McClearn, G. E. (1990). Human behavioral genetics of aging.In J. E. Birren & K. W. Schaie (Eds.), Handbook of the psychology ofaging (3rd. ed.). San Diego, CA: Academic Press.

Richards, T., & Richards, L. (1995). QSR NUD*IST. London: SagePublications.

Ruth, J. E., & Coleman, P. (1996). Personality and aging: Coping andmanagement of the self in later life. In J. E. Birren & K. W. Schaie (Eds.),Handbook of the psychology of aging (4th ed.). San Diego: AcademicPress.

Salthouse, T. A. (1985). A theory of cognitive aging. Amsterdam: North-Holland.

Salthouse, T. A. (1988). Resource-reduction interpretations of cognitiveaging. Developmental Review, 8, 238-272.

Salthouse, T. A. (1991). Theoretical perspectives on cognitive aging. Hills-dale, N): Erlbaum.

Schroots, J. J. F. (1988). On growing, formative change, and aging. In J. E.Birren & V. L. Bengtson (Eds.), Emergent theories of aging. New York:Springer.

Schroots, J. J. F. (Ed.). (1993). Aging, health and competence: The nextgeneration of longitudinal research. Amsterdam: Elsevier SciencePublishers.

Schroots, J. J. F. (1995a). Psychological models of aging. Canadian Journalon Aging, 14, 44-66.

Schroots, J. J. F. (1995b). Gerodynamics: Toward a branching theory ofaging. Canadian Journal on Aging, 14, 74-81.

Schroots, J. J. F. (1996). Theories of aging: Psychological. In J. E. Birren (Ed.),Encyclopedia of gerontology (Vol. 2). San Diego, CA: Academic Press.

Schroots, J. J. F., & Birren, J. E. (1990). Concepts of time and aging inscience. In J. E. Birren & K. W. Schaie (Eds.), Handbook of the psychol-ogy of aging (3rd. ed.). San Diego, CA: Academic Press.

Schroots, J. J. F., Birren, J. E., & Kenyon, G. M. (1991). Metaphors and aging:An overview. In G. M. Kenyon, J. E. Birren, & J. J. F. Schroots (Eds.),Metaphors of aging in science and the humanities. New York: Springer.

Thomae, H. (1970). Theory of aging and cognitive theory of personality.Human Development, 13, 1-16.

Tornstam, L. (1989). Gero-transcendence; A reformulation of the disen-gagement theory. Aging, 1, 55-63.

Tornstam, L. (1992). The quo vadis of gerontology: On the scientific para-digm of gerontology. The Cerontologist, 32, 318-326.

Tornstam, L. (1994). Gero-transcendence: A theoretical and empirical ex-ploration. In L. E. Thomas & S. A. Eisenhandler (Eds.), Aging and thereligious dimension. Westport, CT: Auburn House.

Treas, J., & Passuth, P. M. (1988). The three sociologies: Age, aging and theaged. In F. Borgatta & K. Cook (Eds.), The future of sociology. BeverlyHills, CA: Sage.

Van Geert, P. (1994). Dynamic systems of development — Change betweencomplexity and chaos. New York: Harvester/Wheatsheaf.

Received July 3, 1996Accepted August 3, 1996



Documents

Theoretical Developments in the Psychology of Aging