Personality and individual differences in plasticity

In the last few years, investigators have documented individual differences in many different types of behavioral plasticity. Of particular interest are individual differences in the temporal plasticity of personality traits over extended (ontogenetic) periods of time, because of the relevance of these data to models of behavioral development. We discuss recent empirical studies of the temporal consistency of personality over ontogeny, and models that make contrasting predictions about individual differences in the developmental trajectories of behavioral traits. In addition, we consider recent advances in studies of relationships between personality traits and particular types of behavioral plasticity, including statistical methods which facilitate analyses of relationships between personality traits, contextual plasticity, temporal plasticity and intraindividual variability, and empirical tests of predicted relationships between personality traits and other types of behavioral plasticity (flexibility, learning rates). As the field of animal personality and behavioral plasticity moves from a largely descriptive to a predictive phase, we suggest that there is ample room for empirical tests of recent models that predict individual differences in behavioral developmental trajectories, and for the development of new formal models that make strong predictions about relationships between personality traits and specific types of behavioral plasticity.

Measurement and characterisation of individual differences in need for cognition.

This thesis investigated the measurement of differences between people in tendency to engage in effortful thought. Findings from this research will improve measurement in future research, while also providing insights into the motivation behind this tendency, with implications for diverse applications such as education, career selection, and prejudice.

The relationship between divorce and the psychological well‐being of children with ADHD: differences in age, gender, and subtype

It is generally accepted that Attention‐Deficit/Hyperactivity Disorder (ADHD) results from a dysfunction of the central nervous system, which has led to a commonly held belief that environmental factors play little role in the behavioural problems of children identified as having ADHD. Therefore, the two studies reported in this article investigated the relationship between parental divorce and the psychological well‐being of children with ADHD. Subjects, aged 6 to 18 years, were diagnosed with either the inattentive or combined subtype of the disorder. Firstly, differences in children's behaviour between divorced and non‐divorced families were examined, and subtype, age, and gender differences were evaluated in terms of symptom severity and comorbid conditions. Secondly, parents' perceptions of the impact of their children's behaviour on marital status and family/parental functioning were examined. Parental divorce was associated with greater symptom severity, more externalizing/ internalizing behaviours, and poorer social functioning, but less with academic underachievement. Further, parental divorce was related to adjustment differences in ADHD subtypes, age, and gender. However, the correlation between behaviour problems of children with ADHD and marital/family dysfunction was weak. It may be concluded that parental divorce was associated with the psychological well‐being in children with ADHD, and there is some suggestion that ADHD should be viewed as a bio‐psychosocial disorder.

Describing socioeconomic gradients in children's diets - does the socioeconomic indicators used matter?

Background: 

Individual variation in thermal performance curves: swimming burst speed and jumping endurance in wild-caught tropical clawed frogs

The importance of studying individual variation in locomotor performance has long been recognized as it may determine the ability of an organism to escape from predators, catch prey or disperse. In ectotherms, locomotor performance is highly influenced by ambient temperature (Ta), yet several studies have showed that individual differences are usually retained across a Ta gradient. Less is known, however, about individual differences in thermal sensitivity of performance, despite the fact that it could represent adaptive sources of phenotypic variation and/or additional substrate for selection to act upon. We quantified swimming and jumping performance in 18 wild-caught tropical clawed frogs (Xenopus tropicalis) across a Ta gradient. Maximum swimming velocity and acceleration were not repeatable and individuals did not differ in how their swimming performance varied across Ta. By contrast, time and distance jumped until exhaustion were repeatable across the Ta gradient, indicating that individuals that perform best at a given Ta also perform best at another Ta. Moreover, thermal sensitivity of jumping endurance significantly differed among individuals, with individuals of high performance at low Ta displaying the highest sensitivity to Ta. Individual differences in terrestrial performance increased with decreasing Ta, which is opposite to results obtained in lizards at the inter-specific and among-individual levels. To verify the generality of these patterns, we need more studies on individual variation in thermal reaction norms for locomotor performance in lizards and frogs.

Towards an integration of theories of achievement motivation

This thesis investigated children's school achievement in terms of an integration of three theories of achievement motivation. The three theoretical outlooks were expectancy-value theory (EVT), implicit theories of intelligence (ITI), and flow theory (FT). The first of two studies was an exploratory investigation of the effectiveness of each theory independently and combined to predict children's achievement in four school subjects. The subject areas were maths, reading, instrumental music and sport. Participants were 84 children (40 females and 44 males) aged 9 to 10 years, one of each child's parents, and school teachers of each child in the four subject areas. All data were collected through questionnaires based on the three models. The results indicated that EVT and FT but not ITI accounted for a significant amount of the variance in children's achievement, including effects for subject area and gender. A second confirmatory study tested EVT, FT and an integrated model for the prediction of achievement in maths, reading and instrumental music. The participants were a further 141 children (74 females and 67 males) aged 10 to 11 years, and a parent and teachers of each child. Data collection using questionnaires occurred early in the school year (Timel) and approximately five months later (Time2). For EVT, children and parents’ competence beliefs were significant predictors of children's achievement in each subject area. Females tended to believe themselves more competent at reading and instrumental music and also valued these subjects more highly than boys. Modeling results for flow theory indicated that children's emotional responses to classes (happiness and confusion) were significant predictors of achievement, the type of emotion varying between subject areas and time periods. Females generally had a more positive emotional reaction to reading and instrumental music classes than males did. The integrated model results indicated significant relationships between EVT and flow theories for each subject area, with EVT explaining most achievement variance in the integrated model. Children's and parents’ competence beliefs were the main predictors of achievement at Timel and 2, Subject area and gender differences were found which provide direction for future research. Anecdotal reports of parents and teachers often attest to individual differences in children's involvement in various school domains. Even among children of apparently similar intelligence, it is not uncommon to find one who likes nothing better than to work on a mathematics problem while another much prefers to read a novel or play a musical instrument Some children appear to achieve good results for most of the activities in which they are engaged while others achieve in a less consistent manner, sometimes particularly excelling in one activity. Some children respond to failure experiences with a determination to improve their performance in the future while others react with resignation and acceptance of their low ability. Some children appear to become totally absorbed in the activity of playing sport while others cannot wait for the game to end. The primary research objective guiding the current thesis is how children's thoughts and feelings about school subjects differ and are related to their school achievement. A perusal of the achievement motivation literature indicates several possible models and concepts that can be applied to explain individual differences in children's school achievement. Concepts such as academic self-concept, multiple intelligences, intrinsic and extrinsic motivation, self-beliefs, competence beliefs, subjective task values, mastery and performance goals, ‘Flow’ experiences and social motivation are just some of the constructs used to explain children's achievement motivation, both within and between various activity domains. These constructs are proposed by researchers from different theoretical perspectives to achievement motivation. Although there is much literature relevant to each perspective, there is little research indicating how the various perspectives may relate to each other. The current thesis will begin by reviewing three currently popular theoretical orientations cited in achievement motivation research: subjective beliefs and values; implicit theories of intelligence, and flow experience and family complexity. Following this review, a framework will be proposed for testing the determinants of children's school achievement, both within each of the three theoretical perspectives and also in combination.

The Early Prevention of Obesity in CHildren (EPOCH) collaboration : an individual patient data prospective meta-analysis

Background
Efforts to prevent the development of overweight and obesity have increasingly focused early in the life course as we recognise that both metabolic and behavioural patterns are often established within the first few years of life. Randomised controlled trials (RCTs) of interventions are even more powerful when, with forethought, they are synthesised into an individual patient data (IPD) prospective meta-analysis (PMA). An IPD PMA is a unique research design where several trials are identified for inclusion in an analysis before any of the individual trial results become known and the data are provided for each randomised patient. This methodology minimises the publication and selection bias often associated with a retrospective meta-analysis by allowing hypotheses, analysis methods and selection criteria to be specified a priori.

Methods/Design
The Early Prevention of Obesity in CHildren (EPOCH) Collaboration was formed in 2009. The main objective of the EPOCH Collaboration is to determine if early intervention for childhood obesity impacts on body mass index (BMI) z scores at age 18-24 months. Additional research questions will focus on whether early intervention has an impact on children's dietary quality, TV viewing time, duration of breastfeeding and parenting styles. This protocol includes the hypotheses, inclusion criteria and outcome measures to be used in the IPD PMA. The sample size of the combined dataset at final outcome assessment (approximately 1800 infants) will allow greater precision when exploring differences in the effect of early intervention with respect to pre-specified participant- and intervention-level characteristics.

Discussion
Finalisation of the data collection procedures and analysis plans will be complete by the end of 2010. Data collection and analysis will occur during 2011-2012 and results should be available by 2013.

Individual, social and home environment determinants of change in children's television viewing: the Switch-Play intervention

Understanding potential determinants of change in television (TV) viewing among children may enhance the effectiveness of programs targeting this behaviour. This study aimed to investigate the contribution of individual, social and home environment factors among 10-year-old Australian children to change in TV viewing over a 21-month period. A total of 164 children (49% boys) completed a 19-lesson (9-month) intervention program to reduce TV viewing time. Children completed self-administered surveys four times over 21 months (pre- and post-intervention, 6- and 12-month follow-up). Baseline factors associated with change in TV viewing during the intervention and follow-up periods were: ‘asking parents ≥once/week to switch off the TV and play with them’ (21.6 min/day more than those reporting <once/week, p = 0.007); being able to ‘watch just 1 h of TV per day’ (26.1 min/day less than those who could not, p = 0.010); ‘watching TV no matter what was on’ (36.6 min/day more than those who did not, p < 0.001); and ‘continuing to watch TV after their program was over’ (33.0 min/day more than those who did not, p = 0.006). With every unit increase in baseline frequency of TV viewing with family and friends, children spent on average 4.0 min/day more watching TV over the 21-month period (p = 0.047). Baseline number and placement of TVs at home did not predict change in children's TV viewing over the 21 months. Greater understanding of the family dynamics and circumstances, as well as the individual and social determinants of TV viewing, will be required if we are to develop effective strategies for reducing TV viewing in children.

A prospective study of individual factors in the development of weight and muscle concerns among preadolescent children

The present study was designed to assess body mass index (BMI), self-esteem, parent and peer relations, negative affect, and perfectionism, as predictors of dieting, food preoccupation, and muscle preoccupation, in 326 preadolescent children (150 girls and 176 boys) aged between 8 and 10 years. Preadolescents were tested twice over a 10-month period. BMI was found to be the main predictor of girls' and boys' dieting, both cross-sectionally and longitudinally. Perfectionism was an important predictor of boys' dieting and muscle preoccupation, while self-esteem, peer relations and negative affect predicted girls' muscle preoccupation. The findings are discussed in relation to past research with both preadolescents and adolescents.

Intergenerational differences in food, physical activity, and body size perceptions among African migrants

We assessed intergenerational differences in food, physical activity, and body size perceptions among refugees and migrants from the Horn of Africa living in Victoria, Australia. We used a qualitative design and obtained data from 48 participants (18 individual interviews; 3 semistructured focus groups). Three major themes emerged: (a) food and physical activity, (b) preference of body size and social expectations, and (c) perceived consequences of various body sizes. For parents, large body size was perceived to equate with being beautiful and wealthy; slimness was associated with chronic illness and poverty. Parents adopted strategies that promoted weight gain in children. These included tailored food practices and restricting children&rsquo;s involvement in physical activity. For young people, slimness was the ideal body size endorsed by their peers, and they adopted strategies to resist parental pressure to gain weight. Obesity-prevention programs in this subpopulation need to adopt a multigenerational approach.

Gender differences in emotionality and sociability in children with autism spectrum disorders

Background
Four times as many males are diagnosed with high functioning autism compared to females. A growing body of research that focused on females with autism spectrum disorder (ASD) questions the assumption of gender invariance in ASD. Clinical observations suggest that females with ASD superficially demonstrate better social and emotional skills than males with ASD, which may camouflage other diagnostic features. This may explain the under-diagnosis of females with ASD.

Methods
We hypothesised that females with ASD would display better social skills than males with ASD on a test of friendship and social function. One hundred and one 10- to 16-year-olds (ASD females, n&thinsp;=&thinsp;25; typically developing (TD) females, n&thinsp;=&thinsp;25; ASD males, n&thinsp;=&thinsp;25; TD males, n&thinsp;=&thinsp;26) were interviewed (using the friendship questionnaire (FQ)) with high scores indicating the child has close, empathetic and supportive relationships. One parent of each child completed the FQ to assess whether there are differences in perception of friendships between parents and children.

Results
It was found that, independent of diagnosis, females demonstrated higher scores on the FQ than males. Further, regardless of gender, children with ASD demonstrated lower scores than TD children. Moreover, the effect of ASD was independent of gender. Interestingly, females with ASD and TD males displayed similar scores on the FQ.

Conclusions
This finding is supported by clinical reports that females with ASD have more developed social skills than males with ASD. Further research is now required to examine the underlying causes for this phenomenon in order to develop gender-appropriate diagnostic criteria and interventions for ASD.