Although research has shown that the complex constructs of intelligence and personality are necessarily intertwined, studies exploring this issue in elderly individuals are rare. The importance attached to this interface in older adults becomes particularly clear in light of the debate over the cause and extent of age-related decrements in cognitive performance as well as whether such losses can be ameliorated or not, especially given societal shifts toward increased life expectancies. The present study explored the basis for shifts in personality-ability relationships in adulthood by comparing two samples of older adults, one of which was assessed in 1975 (N = 102, M age = 68.4), and the second of which was assessed in 1995 (N = 100, M age = 72.0), and a sample of younger adults (N = 100, M age = 21.8), also assessed in 1995. Each participant was administered the Holtzman Inkblot Technique and the Gf-Gc Sampler, a measure of crystallized (Gc) and fluid (Gf) abilities. LISREL analyses of both age-related and historical shifts in personality-ability relationships suggested that not only were such shifts associated with cohort differences as reflected in factor loading (lambda) differences between the older samples and the younger sample, as well as between each of the older samples, but also that such connections were weaker among younger adults. These findings are important in revealing that sociocultural shifts in opportunities for continued cognitive growth influence the impact of noncognitive (personality) factors on intellectual functioning in later life. Limitations of the current study, implications of the results, and suggestions for future research are discussed.

Inspection Time (IT) is a speed measure that has been primarily investigated in the field of individual differences. However, Nettelbeck and Wilson (2004) proposed that IT could have promise as a biomarker for functional outcomes, particularly cognitive aging. The premise behind biomarker research is that chronological age is simply a proxy for the physiological and cognitive changes that occur in the body with advancing age. Biomarkers are measures that 'mark' the aging process and represent the biological age of an individual rather than the years since his/her birth. Speed of processing tasks offer promise as biomarkers because decline in speed of processing is one of the most robust findings in cognitive aging research. However, traditionally used tasks are problematic because they confound speed and accuracy and some are sensitive to cohort effects. Inspection time is a speed of processing measure that is free from these problems and is therefore a promising candidate for a biomarker. This dissertation presents the first empirical investigation of this proposition. One hundred and fifty elderly participants were assessed on IT, traditionally used biomarkers (e.g. grip strength, visual acuity), a battery of cognitive tasks (e.g. fluid ability and crystallised ability) and measures of everyday functioning (e.g. activities of daily living). These individuals were assessed on three separate occasions over a period of 18-months. For the biomarkers, initial scores, 6-month change scores and 18-month change scores were generated and used to predict final scores and 18-month change scores on the functional outcomes (cognition and everyday functioning). Results revealed that slow IT at the start of the study was associated with dependence in activities of daily living and poorer fluid ability at the end of the study. There was also evidence that slow IT at the start was associated with decline in fluid reasoning over the subsequent 18-months. Moreover, consistent with the major aims of this study, decline in IT over time was associated with more cognitive problems in daily life and poor fluid ability at the end of the study. Given that initial and change scores for IT were independent, due to the methodology used to estimate them, the two measures explained unique variance in the functional outcome measures.These findings are extremely encouraging, particularly given the relatively short time frame for this study. IT has predictive validity for everyday functioning and cognitive aging over an 18-month period, and therefore, it is concluded that IT has promise as a valid biomarker for functional age. Recommendations for further research include investigating the link between IT and mortality, examining the association between IT and a broader range of functional age measures, the replication of these findings in a different sample, and means for improving the sensitivity and specificity of the current IT estimation procedure. / Thesis (Ph.D.) -- University of Adelaide, School of Psychology, 2006.

Deteriorations in cognitive functioning and sleep are the inevitable parts of the ageing process, and they are two very common complaints among the elderly population. Given their high relevance and great impact on daily functioning, many studies have attempted to address the associations of sleep problems and cognitive functioning with ageing, yet the direction of associations remained unclear. Several recent studies suggested that caffeine, a common psychostimulant present in coffee and tea, might have a beneficial effect on agerelated decline in cognitive functioning. Nonetheless, the dose-dependent effect of caffeine intake on specific domains of cognitive functioning, and the potential cost of compromised nocturnal sleep at high dose of caffeine remained to be investigated. In view of the lack of study on identifying the correlation and interaction between sleep, cognitive functioning, caffeine consumption habit, and age, this thesis reported two studies that clarified these relationships in the elderly population. Furthermore, the studies explored the possibility to utilize sleep and caffeine as a regimen to improve daytime cognitive functioning in the older population. Study 1 was a retrospective study that aimed to examine the relationship between sleep, habitual caffeine consumption, cognitive functioning, and mood in the two different age groups, the young adult and the elderly. Eighty-nine healthy elderly and forty-three healthy young adults participated in this study and completed a battery of neuropsychological assessment and a set of questionnaires. Findings revealed changes in multiple domains of sleep and cognitive functioning upon ageing. The age-related differences in sleep and cognitive functioning were correlated. Moreover, result suggested that regular caffeine consumption has a dose-dependent beneficial effect on cognitive functioning, but the effect was only observed in female. Study 2 was built on the relationship between sleep, cognitive functioning, and caffeine as found in Study 1. It aimed to investigate the effect of caffeine and daytime nap on the cognitive functioning in the healthy elderly adopting a repeated measure, double-blind, placebo-controlled design. Twenty-four healthy elderly were recruited for this study, and each of them were required to attend four experimental sessions with a one-week intersession interval. In each session, participants were required to take a rest or take a nap with or without a certain dosage of caffeine in the afternoon. Comparisons on their cognitive performance before and after the rest/ nap revealed an effect of nap and caffeine on improving subjective feeling of sleepiness and fatigue. Behavioural measurements revealed no effect on daytime nap on cognitive functioning, yet specific sleep stage and certain sleep oscillations were associated with post-nap changes in cognitive functioning. In summary, the present studies demonstrated the associations of sleep and caffeine consumption with cognitive functioning in the elderly. Habitual caffeine consumption was associated with a female-specific beneficial effect on cognitive functioning. Furthermore, daytime nap combined with the use of acute dose of caffeine might not enhance cognitive functioning, but could improve mood and well-being in the elderly. Findings from present studies suggested that further research could explore ways to maximise the benefit of napping in the elderly. / published_or_final_version / Psychology / Doctoral / Doctor of Philosophy

The purpose of this study was to examine the relationship between physical activity (PA) and cognitive function in older adults Additionally, the study sought to determine if older adults adhering to ACSM PA guidelines would exhibit significantly better cognitive function than their less active peers. Thirty-five participants (M= 70.6 ± 4.6 years), 21 males and 14 females free of diagnosed cognitive disorders or prescribed psychotropic medications from the Muncie, IN. region were recruited for analysis. Resting heart rate, blood pressure, health history and basic body composition variables were evaluated to determine study eligibility. The Trail Making Task and Stroop Color and Word Test were used to assess cognitive function. Time spent in sedentary, light and moderate-vigorous PA (MVPA), energy expenditure and total steps were measured for a one-week period by accelerometry (ActiGraph GT3x) and questionnaire (International Physical Activity Questionairre). Weekly MVPA was found to correlate significantly with Stroop Word (W) (r =.446, p = < .05), Stroop Color (C) (r =.389, p = < .05) and Stroop Color-Word (CW) (r =.609, p = < .05) performance outcomes. MVPA was also found to have a significant relationship with Trail Making Test Part B (TMTb) outcomes (r = -.358, p < .05). Energy expenditure was related with cognitive performance where W (r = .416, p = <.05), C (r = .424, p = < .05), CW (r = .656, p = < .05), TMTb (r = -.532, p = < .05) and difference between TMT Parts A and B (TMTdiff) (r = -.485, p = < .05) were significant. Total steps/week were strongly correlated to MVPAACC+ (r = .752, p = < .05) as well as CW scores (r = .388, p < .05). Women were shown to have a stronger relationship between MVPAACC+ and TMTb performance outcomes (r = .732, p < .05). Independent t-tests indicated that older adults participating in > 150 minutes of MVPA weekly perform better on Stroop W, C and CW (p = .003, p = .001, and p = .015, respectively) when compared to less active peers. Increased MVPA indicates improved cognitive performance outcomes in older adults when compared to less active peers. / School of Physical Education, Sport, and Exercise Science

Inspection Time (IT) is a speed measure that has been primarily investigated in the field of individual differences. However, Nettelbeck and Wilson (2004) proposed that IT could have promise as a biomarker for functional outcomes, particularly cognitive aging. The premise behind biomarker research is that chronological age is simply a proxy for the physiological and cognitive changes that occur in the body with advancing age. Biomarkers are measures that 'mark' the aging process and represent the biological age of an individual rather than the years since his/her birth. Speed of processing tasks offer promise as biomarkers because decline in speed of processing is one of the most robust findings in cognitive aging research. However, traditionally used tasks are problematic because they confound speed and accuracy and some are sensitive to cohort effects. Inspection time is a speed of processing measure that is free from these problems and is therefore a promising candidate for a biomarker. This dissertation presents the first empirical investigation of this proposition. One hundred and fifty elderly participants were assessed on IT, traditionally used biomarkers (e.g. grip strength, visual acuity), a battery of cognitive tasks (e.g. fluid ability and crystallised ability) and measures of everyday functioning (e.g. activities of daily living). These individuals were assessed on three separate occasions over a period of 18-months. For the biomarkers, initial scores, 6-month change scores and 18-month change scores were generated and used to predict final scores and 18-month change scores on the functional outcomes (cognition and everyday functioning). Results revealed that slow IT at the start of the study was associated with dependence in activities of daily living and poorer fluid ability at the end of the study. There was also evidence that slow IT at the start was associated with decline in fluid reasoning over the subsequent 18-months. Moreover, consistent with the major aims of this study, decline in IT over time was associated with more cognitive problems in daily life and poor fluid ability at the end of the study. Given that initial and change scores for IT were independent, due to the methodology used to estimate them, the two measures explained unique variance in the functional outcome measures.These findings are extremely encouraging, particularly given the relatively short time frame for this study. IT has predictive validity for everyday functioning and cognitive aging over an 18-month period, and therefore, it is concluded that IT has promise as a valid biomarker for functional age. Recommendations for further research include investigating the link between IT and mortality, examining the association between IT and a broader range of functional age measures, the replication of these findings in a different sample, and means for improving the sensitivity and specificity of the current IT estimation procedure. / Thesis (Ph.D.) -- University of Adelaide, School of Psychology, 2006.

Thesis (Ph.D.)--City University of New York, 2003. / Includes bibliographical references (leaves 88-98).

Thesis (Ph. D.)--University of North Texas, Dec., 2009. / Title from title page display. Includes bibliographical references.

Thesis (Ph. D.)--University of North Texas, August, 2008. / Title from title page display. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--Dept. of Psychology, Concordia University, 1996. / "May 1996." Includes bibliographical references (leaves 178-188). Available also on the Internet.