According to the five-factor theory, personality traits are insulated from the direct effects of the environment and are exclusively biological in origin. Traits develop through childhood and reach mature form in adulthood; thereafter they are stable in cognitively intact individuals. More specifically, traits are said to reach maturity by age 30. The predicted stability is expected to last throughout middle age, though in old age personality could change again, being disrupted by cognitive decline. Therefore, personality becomes set like plaster by age 30 that was referred as plaster hypothesis. The hypothesis states that change in Big Five traits after age 30 were nonexistent or trivial. Later studies showed that personalities showed changes in mean levels after age 30 but they interpret these changes as stemming from intrinsic biological maturation rather than social influences, and they still regard the plaster hypothesis as basically true (McCrea et al., 1999, 2000).
Caspi and Roberts (1999) identified different forms of personality stability. The two most studied, illustrate why researchers differ as to the merits of the two hypotheses. Differential stability refers to the consistency of differences between individuals in a sample of people throughout their lives. Most theorists believe that differential stability is pronounced after the age of 30. Nevertheless, a recent meta-analysis by Roberts and DelVecchio (2000) suggests a gradual increase in inter-individual differences for nearly all traits until after the age of 50. But since differential stability indicators do not allow us to determine whether traits themselves change, we must also consider absolute stability, which refers to stability in the quantity of a personality attribute or trait over time. Many theorists believe that no further significant changes occur once adulthood is reached. However, recent longitudinal studies suggest that absolute stability has been overestimated. Indeed, significant intra-individual changes are observed during adulthood (Helson, Kwan, John, & Jones, 2002). In general, neuroticism and extroversion decline while agreeableness and conscientiousness increase; that is, a psychological maturation appears to occur from the beginning of adulthood. The maturation rate declines with aging, but continuing significant changes occur until an advanced age. For example, the longitudinal study of Field and Millsap (1991) found that neuroticism decreased until age 69 and remained stable until age 83, while agreeableness increased and extroversion declined until age 83.
Hard plaster hypothesis asserts that there should be no age effects on any Big Five dimension after age 30; the soft plaster hypothesis asserts that age effects after age 30 should be weaker than age effects before age 30. A research studied the different age effects during different developmental periods, and about different age effects for men and women and the results show that there is lack of support for the plaster hypothesis, and considerable evidence that directly contradicted it (Potter, Gosling, Srivastava & John, 2003). Mean-levels of personality traits changed gradually but systematically throughout the life span, sometimes more after age 30 than before. Conscientiousness showed substantial change throughout early and middle adulthood, with the strongest effects in earlier; this is the time of life when adults are entering and advancing in the work force and forming committed partnerships (Neyer & Asendropf, 2001), life tasks that have been linked to changes in conscientiousness. Agreeableness showed the largest changes somewhat later, when adults are typically caring for children and performing prosocial behaviors (John & Srivastava, 1999). Neuroticism declined only for women who probably had faced particularly difficult social environments earlier in their lives. Role transitions in work, partnership and childrearing take place throughout early and middle adulthood. People normally enter new jobs in their early 20s and begin advancing in their career thereafter, marry in their mid to late 20s, and raise children in their 30s. If the timing of personality changes is linked to the timing of role transitions, there should be important changes in conscientiousness and agreeableness, and these changes should be apparent well into the 30s. Aside from these normative social role changes, other theories suggest possible changes in personality traits after age 30. People get better at emotion regulation as they grow older and thus tend to have fewer negative emotional experiences (Gross et al., 1997); this could translate into persistently declining levels of neuroticism with age. Socioemotional selective theory (Carstensen, Isaacowitz & Charles, 1999) predicts that as adults progress into middle and later adulthood, they are less and less interested in gathering new information and in meeting new people, implying declining openness and extraversion, and more interested in relationships with close others, implying increasing agreeableness.
Models Suggesting Personality Change
Opposite to the Big Five theory, the timing-of-events model suggests that the personality is not fixed or stable during adulthood but it changes when some key events occur. Baltes (1987) argued that developmental processes may begin at any point in life and are not necessary linear. In other words, a developmental theme, such as dependence, may be more salient in early and late life than it is in middle life. With the normative age-graded, normative history-graded and non-normative influences, human personality development is not restricted in the age before 30 which was suggested by Big Five theory. Normative age-graded influences are experiences caused by biological, psychological and sociocultural forces that are highly correlated with chronological age. They are physical maturation during childhood or typical events during adulthood involving the family, education and occupation. Normative history-degraded influences are events that most people in a specific culture experience at the same time. These events may be biological (e.g. Epidemics), psychological (e.g. particular stereotypes) or sociocultural (e.g. changing attitudes toward sexuality). These effects may differ depending on a person’s age at the time of the event, but most people of a given age will have similar experiences. Non-normative influences are random or rare events that may be important for a specific individual but are not experienced by most people. These may be favorable events such as winning the lottery or an election, or unfavorable ones such as an accident or layoff (Tennant and Pogson, 1995).
Another model suggesting our personality traits are not stable throughout our lives is stage theory. Personality change is normative, age-linked and predictable. There are universal sequences of change that everyone experiences similar events, problems or challenge at about the same time in life. Successful completion of one stage is necessary for successful progression to the next one. Failure to resolve issues or acquire skills at a more fundamental stage undermines success at later stages (Papalia, Sterns, Feldman & Camp, 2002). Erikson, Vaillant, Levinson, Piaget, Jung and Freud are proponents of stage theories. Levinson’s model includes four stages of life. The first stage is pre-adult era ranged the birth to age twenty-two. The ending is marked by individual becoming independent and the beginning takes place in the world of adult responsibility. The second adulthood is from age seventeen to forty-five that major life goals are pursued and crucial choices are made within this period. Occupation, family and life style are the main choices in this period. The third stage is middle adult era ranged from age forty to sixty-five. It is a period of culmination that people move to more senior status in work and community. The last stage is late adulthood era from age sixty. Between eras, there are transitions which require a basic change in the character of one’s life and it may take between three and six years to complete. Within each broad period s are periods of development, each period being characterized by a set of tasks and an attempt to build or modify one’s life structure. For example, in the early adult transition period, from seventeen to twenty-two, the two primary tasks are to move out of the pre-adult world and to make a preliminary step into the adult world. During the settling down period from age thirty-three to forty, the two tasks are to establish a niche in society and to work for progress and advancement in that niche. A pervasive theme throughout the various periods is the existence of the “dream”. It has the quality of a vision, an imagined possibility that generates excitement and vitality. It is out projection of the ideal life (Tennant and Pogson 1995).
Levinson (as cited in Papalia, Sterns, Feldman & Camp, 2002) interviewed of 40 American men with age from 35 to 45 and they worked as either biology professors, novelists, business executives or industrial laborers for about six to ten interviews for each subject. The questions asked focused on the subject's life accounts in their post adolescent years. The interviews focused on topics such as the men's background (education, religion, political beliefs) and major events or turning points in their lives. From this study, Levinson formed a theory of personality development in adulthood. However, in a study conducted by Daniel Shek dealing with mid-life crisis in Chinese Men and Women, Levinson's theory of the presence of a mid-life crisis in middle aged men and women is argued. A sample of 1,501 married adults between the ages of 30 and 60 were given a 15-item Mid-life Crisis Scale. The scale was designed to test the levels of concern of the adults who were divided into six mid-life age groups. The results of the study showed that some of the participants were dissatisfied with their work and personal achievement, but that a majority did not indicate dissatisfaction at the crisis level. Therefore, the findings of this study did not support the idea of a normal mid-life crisis. Also, the results of this research did not show a significant rise or peak in the levels of concern for the adults in any particular age group. This result is in agreement with the findings of McCrae and Costa who concluded that "at any given time, only a small percentage of men are in a crisis, and they are not likely to cluster at any particular age" (Shek, 1996). These findings help to reject Levinson's idea that the mid-life crisis is usually a marker event for people of 40 to 45 years of age (Shek, 1996).
Conclusions
Social roles, life events and social environments change during the life course, and such factors have been suggested as important influences on basic personality traits. In the transaction view, individuals are seen as active agents who play an important role in selecting and shaping their environments, and these environments in turn affect their personalities. Probably the most important social role domains that undergo changes in early and middle adulthood are work, marriage and parenting.
In summary, research different models suggest that the personality exhibits both stability and change. The fact is, we have no choice but to age, and when we do, our social roles may change, we may experience life events such as retirement and widowhood, and we may be coping with altered motor and cognitive functions. Yet, research on personality development is comforting because it contradicts popular beliefs to the effect that individuals become more hypochondriac or rigid in their attitudes and opinions as they age. On the contrary, although changes are less prominent in later life, psychological maturation appears to be a lifelong process. Further research can be focused on the combination of both models suggesting personality stability and change to obtain a more universal and representative results in explaining out personality development.
References
Baltes, P.B. (1987). Theoretical propositions of life-span developmental psychology: On the dynamics between growth and decline. Developmental Psychology, 23: 611-626.
Carstensen, L. L., Isaacowitz, D. M., & Charles, S. T. (1999). Taking time seriously: A theory of socioemotional selectively. American Psychologist, 54, 165-181.
Caspi, A., & Roberts, B.W. (1999). Personality continuity and change across the life course. In L.A. Pervin, & O.P. John (eds.), Handbook of Personality: Theory and Research. New York: Guilford Press, 300-326.
Costa, P. T., Jr., & McCrae, R. R. (1994). Set like plaster: Evidence for the stability of adult personality. In T. F. Heatherton & J. L. Weinberger (Eds.), Can personality change? (pp. 21-40). Washington, DC: American Psychological Association.
Field, D., & Millsap, R.E. (1991). Personality in advanced old age: Continuity or change? Journal of Gerontology: Psychological Sciences, 46: 299-308.
Gross, J. J., Carstensen, L. L., Pasupathi, M., Tsai, J., Skorpen, C. G., & Hsu, A. Y. C. (1997). Emotion and aging: Experience, expression, and control. Psychology and Aging, 12, 590-599
Helson, R., Kwan, V.S.Y., John, O.P., & Jones, C. (2002). The growing evidence of personality change in adulthood: Findings from research with personality inventories. Journal of Research in Personality, 36: 287-306.
John, O. P., & Srivastava, S. (1999). The Big Five Trait taxonomy: History, measurement, and theoretical perspectives. In L. A. Pervin & Oliver P. John (Eds.) Handbook of personality: Theory and research (2nd ed., pp. 102-139). New York: Guilford Press.
McCrae, R. R., Costa, P. T., de Lima, M. P., Simoes, A., Ostendorf, F., Angleitner, A., et al. (1999). Age differences in personality across the adult life span: Parallels in five cultures. Developmental Psychology, 35, 466-477.
McCrae, R. R., Costa, P. T., Simoes, A., Ostendorf, F., Angleitner, A., Hrebickova, M., Avia, M. D., et al. (2000). Nature over nurture: Temperament, personality, and life span development. Journal of Personality and Social Psychology, 78, 173-186
Neyer, F. J., & Asendorpf, J. B. (2001). Personality-relationship transaction in young adulthood. Journal of Personality and Social Psychology, 81, 1190-1204.
Papalia, D. E., Sterns, H. L., Feldman, R. D., Camp, C. J. (2002). Adult development and aging (2nd ed.). New York: McGraw-Hill.
Potter, J., Gosling, S. D., Srivastava, S. & John, O. P. (2003). Journal of Personality and Social Psychology, 84, 1041-1053
Roberts, B.W., & Delvecchio, W.F. (2000). The rank-order consistency of personality traits from childhood to old age: A quantitative review of longitudinal studies. Psychological Bulletin, 126: 3-25.
Shek, D.T.L. (1996). Mid-life Crisis in Chinese Men and Women. Journal of Psychology, 130, 109-119.
Tennant, M. and Pogson, P. (1995) Learning and Change in the Adult Years, San Fransisco: Jossey-Bass. Provides a very helpful overview of life course development for those concerned with lifelong learning.
