Adolescence has been described as a unique period for self-concept development, with an intensified alertness to social comparison as a mechanism for self-knowledge and self-evaluation. However, it... Show moreAdolescence has been described as a unique period for self-concept development, with an intensified alertness to social comparison as a mechanism for self-knowledge and self-evaluation. However, it remains difficult to disentangle the specific influence of these social comparisons on the development of self-descriptions in adolescence. Moreover, it is still unclear how social comparisons impact upon the development of self-views in different domains, such as physical, academic and social self-views. The goal of this study was therefore to examine the development of self-descriptions in different domains across adolescence, and to experimentally test how the development of these self-descriptions is altered by an explicit social comparison context. For this purpose, we developed two tasks which both asked participants (aged 9-25-years, N = 202) for trait self-descriptions but differed in the salience of a social comparison. Results showed consistent age-differences with more positive self-views for children and adolescents in the age-range 9–14 years. The context of explicit social comparison yielded similar as well as additional age-differences that were more dependent upon valence and domain. Moreover, mid-adolescents (15–17 y) were most negatively affected by these social comparisons relative to other ages. Together, this study made a first step in disentangling the specific influence of social comparison outcomes within the development of general self-descriptions, and highlights the importance of social context in studying self-concept in adolescence. Show less
There has been a large spike in longitudinal fMRI studies in recent years, and so it is essential that researchers carefully assess the limitations and challenges afforded by longitudinal designs.... Show moreThere has been a large spike in longitudinal fMRI studies in recent years, and so it is essential that researchers carefully assess the limitations and challenges afforded by longitudinal designs. In this article, we provide an overview of important considerations for longitudinal fMRI research in developmental samples, including task design, sampling strategies, and group-level analyses. We first discuss considerations for task designs, weighing the pros and cons of many commonly used tasks, as well as outlining how the tasks may be impacted by repeated exposure. Secondly, we review the types of group-level analyses that can be conducted on longitudinal fMRI data, analyses which must account for repeated measures. Finally, we review and critique recent longitudinal studies that have emerged in the past few years. Show less
A key process in the life of any multicellular organism is its development from a single egg into a full grown adult. The first step in this process often consists of forming a tissue layer out of... Show moreA key process in the life of any multicellular organism is its development from a single egg into a full grown adult. The first step in this process often consists of forming a tissue layer out of randomly placed cells on the surface of the egg. We present a model for generating such a tissue, based on mechanical interactions between the cells, and find that the resulting cellular pattern corresponds to the Voronoi tessellation of the nuclei of the cells. Experimentally, we obtain the same result in both fruit flies and flour beetles, with a distribution of cell shapes that matches that of the model, without any adjustable parameters. Finally, we show that this pattern is broken when the cells grow at different rates. Show less
Constructing a knowledge representation from multiple texts requires the integration of information across texts. The aim of the current study was to investigate how elementary school students... Show moreConstructing a knowledge representation from multiple texts requires the integration of information across texts. The aim of the current study was to investigate how elementary school students integrate information across multiple text passages and, particularly, whether students use information from a prior text to improve understanding of a current text. A sample of 105 children in grades 4 and 6 participated in the experiment. The multiple-text integration paradigm was used to study integration processes across texts during reading. Recall and (application) questions were used to investigate the extent to which information from different text passages was integrated into knowledge representations after reading. Individual differences in reading comprehension ability and working memory were also considered. The results indicate that children in both grades spontaneously activate information from an earlier text to aid their understanding during reading, and that they integrate information across texts in their knowledge representations. This was the case regardless of grade or individual differences in reading-comprehension ability and working memory. These findings provide insight into the mechanisms that may be involved in the integration of information across texts. Show less
Many hunter-gatherer groups live on the outskirts of wider society, experiencing poor health outcomes with little access to medical care. From a development perspective, key interventions include... Show moreMany hunter-gatherer groups live on the outskirts of wider society, experiencing poor health outcomes with little access to medical care. From a development perspective, key interventions include the sedentarisation of these mobile peoples into camps nearby larger towns with sanitation infrastructure and medical care, as increased access to services is assumed to improve outcomes. However, recent research in the Agta (Philippine foragers from North-east Luzon) has demonstrated that individuals residing in more ‘developed’ communities suffer from increased morbidity and mortality. Here, using quantitative and ethnographic data on health collected between 2002 and 2014, we explore why this trend occurs by examining the relationship between key development initiatives with self-reported illness and the uptake of medical interventions with 415 Agta men, women and children. We demonstrate that health outcomes worsen as sedentarisation progresses, despite some increases in medical access. We argue this is because the development paradigm is not evidence-based, but rather stems from an ideological dislike of mobile hunter-gatherer lifestyles. Compounded by cultural insensitivity and daily discrimination, current interventions are ill-suited to the unique needs of hunter-gatherers, and thus ineffective. Based on our findings we offer future short and long-term policy suggestions which seek to reduce the Agta's vulnerability, rather than increase it. Show less
Van der Cruijsen, R.; Peters, S.; Aar, L.P.E. van der; Crone, E.A. 2018
Neuroimaging studies in adults showed that cortical midline regions including medial prefrontal cortex (mPFC) and posterior parietal cortex (PPC) are important in self-evaluations. The goals of... Show moreNeuroimaging studies in adults showed that cortical midline regions including medial prefrontal cortex (mPFC) and posterior parietal cortex (PPC) are important in self-evaluations. The goals of this study were to investigate the contribution of these regions to self-evaluations in late childhood, adolescence, and early adulthood, and to examine whether these differed per domain (academic, physical and prosocial) and valence (positive versus negative). Also, we tested whether this activation changes across adolescence. For this purpose, participants between ages 11–21-years (N = 150) evaluated themselves on trait sentences in an fMRI session. Behaviorally, adolescents rated their academic traits less positively than children and young adults. The neural analyses showed that evaluating self-traits versus a control condition was associated with increased activity in mPFC (domain-general effect), and positive traits were associated with increased activity in ventral mPFC (valence effect). Self-related mPFC activation increased linearly with age, but only for evaluating physical traits. Furthermore, an adolescent-specific decrease in striatumactivation for positive self traits was found. Finally, we found domain-specific neural activity for evaluating traits in physical (dorsolateral PFC, dorsal mPFC) and academic (PPC) domains. Together, these results highlight the importance of domain distinctions when studying self-concept development in late childhood, adolescence, and early adulthood. Show less
