While a growing body of research indicates that older adults typically perform more poorly on many types of memory tasks than do younger adults, relatively little research has addressed the question of whether this trend continues unchanged into the late ninth and tenth decades of life. Such decrements in memory have been reported as linear declines from early adulthood up until about 80 years of age. Questions arise as to whether such memory declines slow or accelerate in very advanced aging, and to what extent differences are due to aging, per se, or variables that intervene between age and memory.To address these two questions, six memory types - verbal recall, nonverbal recall, short-term memory, working memory, face recognition, and prospective memory - were examined using both cross-sectional and longitudinal methodologies. The six types of memory and the influence of verbal processing speed, nonverbal processing speed, and intelligence were examined in mixed-gender groups of 20 - 40 (n = 40, M = 30.7, SD = 5.52), 50 - 70 (n = 44, M = 59.2, SD = 4.94), and 85+ year olds (n = 42, M = 87.8, SD = 2.43), at two points, the second occurring two years after the first. Each participant completed tests of word recall, geometric shapes recall, short-term memory (digit span), working memory (letter-number sequencing), face recognition, and prospective memory. Additionally, there were two processing speed tasks (Identical Pictures and Finding As), and the National Adult Reading Test of verbal fluency was used to estimate intelligence. The Mini-Mental State Examination and the Beck Depression Inventory (BDI-II) were used to screen for dementia and depression, respectively.At Time 1 testing the 85+ participants showed declines in all memory types (compared to the 20 - 40 year olds). Nonverbal recall (66.2% lower than the young group), working memory (46.2%), verbal recall (45%), and prospective memory (38.2%) produced the largest differences, short-term memory (12.3%) and face recognition (14.7%) the least. Two years later, the 85+ years old participants had shown further declines, relative to the 20 - 40 years group. Nonverbal recall (72.3% lower than the young group), prospective memory (63.2%), working memory (55.3%), and verbal recall (54.7%) continued to produce the largest decrements, with short-term memory (18.9%) and face recognition (19.8%) the least. The results for the young and middle participants did not change appreciably between Time 1 and Time 2. The difference between unadjusted scores and scores adjusted for intelligence, verbal processing speed, and nonverbal processing speed, increased markedly between Time 1 and Time 2 testing for the oldest-old participants.These findings support the view that while memory declines may be approximately linear from age 20 to 80 years, there is a sharp decline in most types of memory after the age of 85 years, recall and working memory suffering the most. Intelligence and processing speed have an effect on some types of memory, but age is by far the largest contributor to memory decline. Furthermore, as expected, all memory types declined over the two-year period, with prospective memory, verbal recall, nonverbal recall, and working memory showing the greatest declines. Short-term memory and face recognition declined at a noticeably slower rate.

This thesis has three key aims, firstly to explore the effects that perceived age and ability have on person perception. Secondly to discover how these two constructs add to the theory on person perception and thirdly, to test a new methodological approach to the study of person perception.

This thesis has three key aims, firstly to explore the effects that perceived age and ability have on person perception. Secondly to discover how these two constructs add to the theory on person perception and thirdly, to test a new methodological approach to the study of person perception.

Perceptions of increased rates of violence worldwide have heightened the need to understand what children think about their experiences as victims or witnesses of violence. Few studies have examined violence from the viewpoint of children. The purpose of this study was to examine children's perceptions of the prevalence, incidence, and impact of violence experienced or witnessed by them and to explore the factors that might mitigate and reduce its impact. A national survey of New Zealand children, aged 9 to 13 years, with a representative sample of 2,077 children from 28 randomly selected schools of various sizes, geographic areas and socioeconomic neighbourhoods was undertaken. A questionnaire was developed for children to report the nature and extent of physical, sexual and emotional violence (including bullying) experienced within their main contexts (home and school). To assess the impact of this violence, as well as children's perceptions of school, their coping experiences, and the extent to which they used violence in their own interpersonal relationships, analyses of data comprised frequencies, bivariate correlations, t-tests, and multiple regressions. Results showed high prevalence rates of physical, emotional, and sexual violence. Comparison of the three types of violence revealed emotional violence to be the most prevalent form of violence and as having more impact on children than physical violence. Sexual violence had the most overall impact. Witnessing violence was more prevalent and, except for sexual victimisation, also had greater impact than direct violence. All types of violence involving adults were rated higher than violence involving children. The study also examined the ethical considerations and philosophy underpinning research that involves children. Guided by Article 12 of the United Nations Convention on the Rights of the Child, the results support the controversial ethical decision to adopt a passive consent procedure. The study demonstrated children's competence to express the ways in which violence has affected them. Conclusions are that effective development of policy and provision should be based on data that reflects children's perceptions of the violence in the context of their own lives

<p>This thesis outlined a novel operationalization and extension of the thrifty phenotype and fetal overnutrition hypotheses, two evolutionary developmental hypotheses stemming from the developmental origins of health and disease perspective, for developmental pathways from prenatal risk through child growth to early puberty. Support has accumulated for both, but previous studies have not clearly determined which hypothesis better predicts early puberty. Using the Fragile Families and Child Wellbeing Study (<i>n</i>=4898), the thrifty phenotype and fetal overnutrition pathways were tested against each other, separately by sex, and race/ethnicity for adrenal, and gonadal pubertal markers. Results indicated that in general, both hypotheses were supported. Contrary to hypotheses, the thrifty phenotype pathway did not predict perceived pubertal timing better in boys and the fetal overnutrition pathway did not predict perceived pubertal timing best in girls. Instead, both pathways predicted puberty equally well between girls and boys and the fetal overnutrition pathway stemming from maternal gestational weight gain was stronger than the pre-pregnancy BMI pathway. Individual paths of the hypothesized pathways were generally supported when analyzed by race/ethnicity group separately, but support for the entire pathways were sparse. Implications of this work are that pubertal timing may be similarly programmed by restrictive and overnutrition prenatal risks, both should be prioritized, and that interventions for maternal gestational weight should be prioritized over interventions for pre-pregnancy BMI for reducing rates of early puberty. </p>

Genetic and home chaos influences in early childhood have been independently associated with externalizing problems, characterized by inattentive, hyperactive, and aggressive behaviors. However, the Behavioral Genetics approach indicates that genetic and environmental influences, although independently effective, interact to produce behavior throughout development. Thus, this thesis uses two samples, the Early Growth and Development study (EGDS), n= 564, and the Avon Longitudinal Study of Parents and Children (ALSPAC), n= 8,952, and two genetically-sensitive approaches, a parent-child adoption approach and a polygenic scoring approach, to examine how genetic influences and home chaos interact in early childhood (age 3-4) to predict externalizing problems later in childhood (age 7). Results indicate that, although home chaos is correlated with later externalizing problems, the effect is reduced in the context of earlier externalizing, possibly suggesting that home chaos is most salient for concurrent, not later, externalizing problems. In addition, genetic influences were not predictive of externalizing problems in either study, nor was the interaction of home chaos and genetic influences. This pattern of results suggests that, although home chaos may be an important factor for concurrent externalizing problems, other factors, e.g., parenting style and prenatal risk, may be more salient than home chaos, especially in interaction with genetic effects. Further, failure to find genetic influence in this thesis suggest that accounting for the broad scope of genetic influences on complex traits like externalizing and the specific genetic risk for individual externalizing phenotypes is important in attempts to find genetic influence and interaction.

Adolescence is a time of great changes, a time where experimentation and exploration is expected and when the values of authority figures are examined and challenged. Adolescents will experiment and push the boundaries of all aspects of their life in order to find their own place and identity in a world that has changed its expectations of them. Use of drugs is one of the ways that they do this. Australian adolescents grow up in a society where alcohol and tobacco is an acceptable part of daily life. Their use of drugs is at least on par with and in some cases exceeds that of the general population. The overall goals of this research were to gain more information on drug use of Australian adolescents, using existing data sets. This research examined, using a number of different age groups, the differences in adolescent drug use between urban and rural Australia for lifetime use, use in the last year and use in the last month using the 2002 edition of the Australian School Student Alcohol and Drug (ASSAD) survey series in conjunction with the 2001 National Drug Strategy Household Survey (NDSHS). It also used these data sets to investigate differences between indigenous adolescents and non-Indigenous adolescents and whether there were any differences in adolescent drug use across socio-economic status groups. Four hypotheses were developed. The first was that rural adolescents are more likely than urban adolescents to use licit drugs and the second was that urban adolescents are more likely than rural adolescents to use illicit drugs. Thirdly, that Indigenous adolescents are more likely than non-Indigenous adolescents to use both licit and illicit drugs and the fourth was that adolescents from low socio-economic status (SES) groups are more likely than adolescents from high SES groups to use licit and illicit substances. The data offered little support for any of the hypotheses. The hypothesis on rural adolescents being more likely to use licit drugs was supported by the ASSAD surveydata but not the NDSHS. All other hypotheses were not supported by either of the data sets. While there are aspects of the information from the two data sets that are contradictory making it difficult to prove or disprove the hypotheses formulated for this research, they highlighted a number of aspects of adolescent drug use. The first of these is that this research supports the premise that rural adolescent drug use rates are converging with urban drug use rates for younger adolescents. It also highlighted that there are a large number of rural school students who are using alcohol and cannabis. The ASSAD data also confirmed other Australian research showing that Indigenous adolescents are less likely than their non-Indigenous counterparts to use alcohol. Both data sets confirmed previous research by indicating that adolescents from the high SES groups are more likely than their counterparts in the lower SES groups to consume alcohol. Further investigation is needed to find out why the data sets did not substantiate each other and to gain further insight into the consumption of alcohol by Indigenous adolescents and adolescents from the higher socio-economic status groups. Increasing the samples of Indigenous people in both of the data sets and lobbying the Australian Bureau of Statistics to increase their sample for the Indigenous Social Survey to include 12-14 year olds should give more information on Indigenous adolescents that could be used in research and prevention activities.

Despite executive function deficits now been examined in relation to the propensity to commit crimes in the general offending population, to date there has been little investigation of this within an intellectually disabled offending sample. The aim of the present study was to undertake a content analysis of the offending patterns and general behavior of Disabilities SA clients with a view to ascertaining whether such an assessment is justified for this offending group. The present study involved content analysis of five participants, currently clients of Disabilities SA. A coding schema was used to assess for evidence of four executive functions: Learning from previous experience; Engaging in logical reasoning; Impulse control; and Understanding the reactions of others. Findings suggest that offenders with intellectual disability have difficulties in all four areas. These findings are discussed in terms of the need for more comprehensive assessment and treatment implications.

<p>Infant exposure to the microbial and allergenic content of indoor floor dust has been shown to play a significant role in both the development of, and protection against, allergies and asthma later in life. Resuspension of floor dust during infant locomotion induces a vertical transport of particles to the breathing zone, leading to inhalation exposure to a concentrated cloud of coarse (> 1μm) and fine (≤ 1μm) particles. Resuspension, and subsequent exposure, during periods of active infant locomotion is likely influenced by gait parameters. This dependence has been little explored to date and may play a significant role in floor dust resuspension and exposure associated with forms of locomotion specific to infants. This study explores associations between infant locomotion dynamics and floor dust resuspension and exposure in the indoor environment. Infant gait parameters for walking and physiological characteristics expected to influence dust resuspension and exposure were identified, including: contact frequency (steps min^-1), contact area per step (m²), locomotion speed (m s^-1), breathing zone height (cm), and time-resolved locomotion profiles. Gait parameter datasets for standard gait experiments were collected for infants in three age groups: 12, 15, and 19 months-old (m/o). The gait parameters were integrated with an indoor dust resuspension model through a Monte Carlo framework to predict how age-dependent variations in locomotion affect the resuspension mass emission rate (mg h^-1) for five particle size fractions from 0.3 to 10 μm. Eddy diffusivity coefficients (m² s^-1) were estimated for each age group and used in a particle transport model to determine the vertical particle concentration profile above the floor.</p><p>Probability density functions of contact frequency, contact area, locomotion speed, breathing zone height, and size-resolved resuspension mass emission rates were determined for infants in each group. Infant standard gait contact frequencies were generally in the range of 100 to 300 steps min^-1and increased with age, with median values of 186 steps min^-1for 12 m/o, 207 steps min^-1 for 15 m/o, and 246.2 steps min^-1 for 19 m/o infants. Similarly, locomotion speed increased with age, from 67.3 cm s^-1at 12 m/o to 118.83 cm s^-1 at 19 m/o, as did the breathing zone height, which varied between 60 and 85 cm. Resuspension mass emission rates increased with both infant age and particle size. A 19 m/o infant will resuspend comparably more particles from the same indoor settled dust deposit compared to a 15 m/o or 12 m/o infant. Age-dependent variations in the resuspension mass emission rate and eddy diffusivity coefficient drove changes in the vertical particle concentration profile within the resuspended particle cloud. For all particle size fractions, there is an average of a 6% increase in the resuspended particle concentration at a height of 1 m from the floor for a 19 m/o compared to a 12 m/o infant. Time-resolved locomotion profiles were obtained for infants in natural gait during free play establish the transient nature of walking-induced particle resuspension and associated exposures for infants, with variable periods of active locomotion, no motion, and impulsive falls. This study demonstrates that floor dust resuspension and exposure can be influenced by the nature of infant locomotion patterns, which vary with age and are distinctly different from those for adults.</p>

<p>Functional impairment is increasingly prevalent among middle-aged and older adults, with 2 in 5 adults over the age of 65 having some form of disability, the majority being limitations on mobility. Many older adults are able to maintain functional capacity well into later life, but the factors that contribute to high levels of function and the mechanisms by which they operate are unclear, although prior work has demonstrated the importance of social relationships for health. Guided by principles from the life course perspective and perspectives on social connectedness, this dissertation examined the role of social connectedness across the life course as a predictor of functional capacity in adulthood. I used existing longitudinal data from the national Midlife in the United States (MIDUS) study to pursue three central aims.</p> <p><br></p> <p>First, Paper 1 compared theoretical and data-driven approaches to classifying life course relationships, including multiple dimensions of social connectedness at different time points across the life course. Results showed that the data-driven approach (i.e., latent profile analysis) was a stronger predictor of functional limitations than the theoretical approach and revealed relationship trajectories consistent with life course cumulative processes. Second, using the profiles obtained from Paper 1, Paper 2 probed the association between life-course social connectedness and functional limitations by examining the potential mediating role of candidate biological and behavioral mechanisms, and moderation by socioeconomic status (SES). Paper 2 findings suggested that observed differences in later-life functional limitations based on life-course social connectedness can be at least partially explained by physical activity, but do not vary by SES. Contrary to hypotheses, inflammation was not a significant mediator. Third, Paper 3 used monozygotic twin data and within-family analyses to sharpen the focus on potential causal associations between life-course social connectedness and adult functional status. Results suggested that the association is likely driven by genetic and/or shared environmental influences. </p> <p><br></p> <p>Taken together, these results add to our understanding of social connectedness and health and address important gaps in the literature. These findings are used to generate theory- and intervention-relevant insights into the successful maintenance of health, independence, and function across the lifespan.</p>