June Chaikelson

Structural equation model of intellectual change and continuity and predictors of intelligence in older men

This study examined the effects of abilities as a young adult, an engaged lifestyle, personality, age, and health on continuity and change in intellectual abilities from early to late adulthood. A battery of measures, including a verbal and nonverbal intelligence test, was given to 326 Canadian army veterans. Archival data provided World War Two enlistment scores on the same intelligence test for this sample: Results indicated relative stability of intellectual scores across 40 years, with increases in vocabulary and decreases in arithmetic, verbal analogies, and nonverbal skills. Young adult intelligence was the most important determinant of older adult performance. Predictors for verbal intelligence were consistent with an engagement model of intellectual maintenance but also indicated the importance of introversion-extraversion and age. Nonverbal intelligence in late life was predicted by young adult nonverbal scores, age, health, and introversion-extraversion.

The role of psychosocial context, age, and intelligence in memory performance of older men

The hypothesis that psychosocial contextual factors contribute to developmental changes in memory was examined using 326 male World War II veterans. Availability of young adult intelligence scores made it possible to separate the contributions of contextual variables and age to maintenance of general intelligence from their direct contributions to performance on 4 memory tasks. Being younger, healthier, more educated, more introverted, more intellectually active, and more satisfied with social support predicted less intellectual decline and, indirectly, better memory performance. Age, personality, locus of control, and extent of social support directly contributed to performance on 1 or more memory tasks. Age contributions were consistent with Craiks (1986) proposed continuum of task demands for self-initiated effort. Possible elaborations of Craiks hypothesis to accommodate contextual variables are suggested.

Individual Differences in Trajectory of Intellectual Development Over 45 Years of Adulthood

The hypothesis that individual differences in adult intellectual development reflect variation in life context and personality was examined in 132 World War II (WWII) veterans. Intelligence data from the Canadian Army M Test were available for 3 occasions, WWII, 1984-1986 (Int85), and 1989-1991 (Int90). Performance declined over the 45 years on 5 subtests but improved on the 6th, Vocabulary. Correlations between WWII and Int90 scores showed considerable stability of individual differences in intelligence over 45 years. Younger age predicted less decline over 45 years on all subtests; a more engaged lifestyle predicted less decline on most subtests, and better health and greater introversion predicted less decline on some subtests. Predictors of change since Int85 were similar to those for the whole period. Implications for theories of adult intellectual development are discussed.

Everyday activity parameters and competence in older adults.

Parameters of everyday activities in relation to cognitive, social, and emotional competence were examined in 2 studies. The parameters included frequency, difficulty, importance, intentions for future activities, changes in past activities, and ability of performance. The challenge hypothesis, in which performance of optional activities experienced as moderately difficult is associated with greatest well-being, was also tested. Two samples of older adults completed a life history interview and measures of psychological functioning. Parameters of activities necessary for maintaining an independent engaged lifestyle were measured by the Everyday Activities Questionnaire. In both studies, competence variables helped explain activity parameters independently of age and demographic variables. There was no support for the challenge hypothesis in either study.

Age-related differences in worry and related processes.

This study investigated the hypothesis that older adults would show age-related reductions in the tendency to worry in both their retrospective accounts and through cross-sectional age comparisons with a sample of younger adults. We also sought to determine whether age differences would be evident in psychological processes associated with a tendency to worry in general adult samples (intolerance of uncertainty and beliefs in the functional value of worry). Support was found for the hypothesized age-related reduction in worry in both retrospective reports among the older adults and cross-sectional age comparisons. Older adults were also found to report less intolerance of uncertainty and less belief in the functional value of worrying compared to younger adults. These findings suggest that worry-proneness is reduced in late adulthood and that a greater ability to tolerate uncertainty in life and to see less value in worrying may partially account for this. Developmental and contextual changes that may account for these findings are considered.

Measurement of Activity in the Elderly: The Activities Checklist

This study assessed the reliability and validity of the Activities Checklist (Reid & Ziegler, 1981) as well as its utility for predicting cognitive functioning in the elderly. Data were drawn from two longitudinal projects where elderly subjects had been tested on two occasions approximately five years apart. Test-retest reliabilities were .54 and .43 for the larger ( N = 158) and smaller ( N = 76) samples respectively. Validity was demonstrated by an age shift towards more passive activities and by positive correlations with education, occupational status, health and well-being. Weighted versions of activity scores were not superior to unweighted versions as predictors of cognitive functioning. For both samples activity levels significantly predicted performance on some cognitive measures. It was concluded that the Activities Checklist is a potentially useful instrument to employ in the study of individual differences in cognitive aging.

Testing Continuity and Activity Variables as Predictors of Positive and Negative Affect in Retirement

This study tested predictions based on continuity and activity theories, examining effects of continuity and change in activity parameters on positive affect (PA) and negative affect (NA). Retired men and women (N = 368) completed measures of everyday activities and affect, repeating the measures after 2 years. Continuity of activity parameters and affect was dominant, although number of activities decreased and ability in activities and NA increased. Changes in activity predicted changes in affect across time. Increased activity frequency, ability, ease, and future intentions predicted higher PA, and increased ability and ease in activity predicted lower NA. Maintaining same levels in activity parameters usually resulted in maintained PA. The results were interpreted as providing some support for both theories.

Models of intelligence in late life: comment on Hultsch et al. (1999).

The authors comment on D. F. Hultsch, C. Hertzog, B. J. Small, and R. A. Dixons (1999) report of the latest results of the Victoria Longitudinal Study, which are presented as a test of the engagement hypothesis, and on their reanalysis of the data from the Veterans Study (Pushkar Gold et al., 1995), which proposes an alternative model of intellectual function. Differences between the methodologies, variables, and concepts of engaged lifestyle in the 2 studies lead to different tests of the engagement hypothesis and different conclusions. Failure to report specified paths and unjustified assumptions lessen the credibility of the Hultsch et al. model for the Veterans Study data. The authors conclude that their original model, which indicates a small but significant effect of engaged adult lifestyle on the maintenance of intellectual verbal abilities in later life, provides a better explanation of the Veterans Study data.

Cognitive changes with aging in schizophrenia

Hospitalized, male chronic schizophrenics (N = 21) in their late sixties performed as well as those in their early forties when normal age effects were determined on measures of verbal fluency, picture anomaly recognition, tapping speed, and maze learning. The findings contraindicated the Kraepelinian view of schizophrenia as a deteriorative disorder and were more in accord with recent longitudinal evidence of clinical stabilization and amelioration of disruptive symptoms in chronic schizophrenia.

Emergent Values and the Experience of Aging

This study examined the role of values or guiding principles emerging from the life histories and reflections of 111 older adults as predictors of the experience of aging. Participants completed a detailed life history interview in which they described themselves on 10 major life dimensions. They also completed standardized questionnaires of well-being, personality traits, and intolerance of uncertainty. Participants expressed a mix of prosocial and self-interest values in their interviews. Multiple regression analyses indicated that social support and intolerance of uncertainty positively predicted the extent of values articulated in the interviews. Better quality of aging was predicted positively by extent of emergent values and greater well-being and negatively by age. The results indicate that an examination of values provides a unique contribution to the understanding of the experience of aging.