The effect of peers' theory of mind on children's own theory of mind development: A longitudinal study in middle childhood and early adolescence

While there is considerable evidence that children's early ability to understand others' mental states, called "theory of mind," is shaped by family experiences, it remains unclear whether children's social interactions at school influence theory of mind (ToM) beyond early childhood. We tested whether the mean level ("quantity") and/or the diversity ("variety") of peers' ToM influenced children's own ToM. We also examined whether peer effects on ToM were independent of possible confounding variables (e.g., verbal ability, social isolation) and comparable across children with different initial levels of ToM and social status. Four hundred fifty-four 8-12-year-old children completed assessments of ToM and peer and friendship nominations at baseline and (for ToM only) 1 year later. The variety (but not the quantity) of peers' ToM predicted the development of children's ToM over and above control variables. The magnitude of the peer effect was comparable across different levels of children's ToM and between children indexed as socially isolated and those who were not. These findings fit with sociocultural models and highlight the importance of the school environment in the development of ToM. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Children in ethnically diverse classrooms and those with cross-ethnic friendships excel at understanding others' minds

This study examined the link between classroom ethnic diversity, cross-ethnic friendships, and children's theory of mind. In total, 730 children in the United Kingdom (54.7% girls, 51.5% White) aged 8 to 13 years completed measures of theory of mind in 2019/2020. Controlling for verbal ability, executive function, peer social preference, and teacher-reported demographic characteristics, greater classroom ethnic diversity provided opportunities for cross-ethnic friendships, and children with cross-ethnic friendships performed better than peers without cross-ethnic friendships on theory of mind. These results extend accounts of intergroup contact by using direct assessments of children's theory of mind and advance social accounts of theory of mind by demonstrating how experiences outside the family are linked with theory of mind.

Rare neurodevelopmental conditions and parents' mental health - how and when does genetic diagnosis matter?

BACKGROUND

Parents of individuals with rare neurodevelopmental conditions and intellectual disabilities (ID) are vulnerable to mental health difficulties, which vary between parents and within parents over time. The underlying cause of a child's condition can influence parents' mental health, via uncertain pathways and within unknown time-windows.

RESULTS

We analysed baseline data from the IMAGINE-ID cohort, comprising 2655 parents of children and young people with ID of known genetic origin. First, we conducted a factor analysis of the SDQ Impact scale to isolate specific pathways from genetic aetiology to parents' mental health. This suggested a two-factor structure for the SDQ Impact scale, with a "home & distress" dimension and a "participation" dimension. Second, we tested via structural equation modelling (SEM) whether genetic diagnosis affects Impact and mental health directly, or indirectly via children's characteristics. This analysis identified an indirect pathway linking genetic aetiology to parents' mental health, serially through child characteristics (physical disabilities, emotional and behavioural difficulties) and Impact: home & distress. Third, we conducted moderation analysis to explore the influence of time elapsed since genetic diagnosis. This showed that the serial mediation model was moderated by time since diagnosis, with strongest mediating effects among recently diagnosed cases.

CONCLUSIONS

There are multiple steps on the pathway from ID-associated genetic diagnoses to parents' mental health. Pathway links are strongest within 5 years of receiving a genetic diagnosis, highlighting opportunities for better post-diagnostic support. Recognition and enhanced support for children's physical and behavioural needs might reduce impact on family life, ameliorating parents' vulnerabilities to mental health difficulties.

Measures of individual differences in adult theory of mind: A systematic review

Theory of mind (ToM), the ability to understand and reason about mental states, has been extensively studied in young children and clinical populations. A growing interest in examining ToM in adults has emerged over the past two decades, but the extent to which existing measures are suitable for studying adults, especially in detecting individual differences, remains understudied. In this systematic review of 273 studies, 75 measures used to investigate individual differences in adults' ToM were identified. Their sensitivity to individual differences, reliability, and validity were examined. Results suggest that ceiling effects were prevalent, and there was limited evidence to establish the reliability or validity of these measures due to the lack of reports of psychometric properties. Interrelations among measures were inconsistent. These findings highlight the need for future empirical and theoretical work to broaden the evidence base regarding psychometric properties of measures, to develop new measures, and to lay out more specific hypotheses about the relevance of ToM for different social outcomes.

Association between childhood maltreatment and callous-unemotional traits in youth: A meta-analysis

Callous-unemotional (CU) traits (i.e., lack of remorse or guilt, callous lack of empathy, deficient concern for the feelings of others) in youth with conduct problems confer risk for a particularly severe and persistent form of antisocial behaviour. Previous research has linked childhood maltreatment as a potential risk factor for CU traits, both primary (i.e., genetically underpinned) and secondary (i.e., environmentally influenced) variants, but findings have been inconsistent, and the association has not yet been tested in a meta-analysis. To address this gap, we conducted a meta-analysis to assess the nature and strength of the associations between childhood maltreatment and its subtypes with CU traits and potential variants (i.e., primary and secondary CU traits). A systematic search identified 29 eligible studies including 9,894 participants (42% female) between the ages of 3 and 18 years (Mage=14.22 years, SD = 1.07). Results revealed a significant moderate positive association between childhood maltreatment and CU traits. All subtypes of maltreatment bar sexual abuse were significantly associated with CU traits. However, it was not possible to compare primary and secondary CU traits directly due to inconsistencies in how they are defined. The limitations posed by current research signal the need for clinical and operational guidelines on how to define primary and secondary CU traits. Additionally, prospective longitudinal, genetically informed research is needed to clarify if maltreatment is a causal risk factor for CU traits.

Developmental links between executive function and emotion regulation in early toddlerhood

Developmental associations between poor executive function (EF) and problem behaviors in toddlerhood indicate that the interplay between cognition and affect begins very early in life (Hughes, Devine, Mesman, & Blair, 2020). However, very few longitudinal studies of toddlers have included direct measures of both EF and emotion regulation (ER). In addition, while models of ER highlight the importance of situational contexts (e.g., Miller, McDonough, Rosenblum, Sameroff, 2005), existing work is limited by a heavy reliance on lab-based observations of mother-child dyads. Addressing these twin gaps, the current study of 197 families included video-based ratings of ER in toddlers' dyadic play with both mothers and fathers at each of two time-points (14- and 24-months), with parallel measures of EF being gathered in each home visit. Our cross-lagged analyses showed that EF at 14 months predicted ER at 24 months, but this association was limited to observations of toddlers with mothers. It was also asymmetric: ER at 14 months did not predict EF at 24 months. These findings support co-regulation models of early ER and highlight the predictive utility of very early individual differences in EF.

Machine learning and deep learning systems for automated measurement of "advanced" theory of mind: Reliability and validity in children and adolescents

Understanding individual differences in theory of mind (ToM; the ability to attribute mental states to others) in middle childhood and adolescence hinges on the availability of robust and scalable measures. Open-ended response tasks yield valid indicators of ToM but are labor intensive and difficult to compare across studies. We examined the reliability and validity of new machine learning and deep learning neural network automated scoring systems for measuring ToM in children and adolescents. Two large samples of British children and adolescents aged between 7 and 13 years (Sample 1: N = 1,135, Mage = 10.22 years, SD = 1.45; Sample 2: N = 1,020, Mage = 10.36 years, SD = 1.27) completed the silent film and strange stories tasks. Teachers rated Sample 2 children's social competence with peers. A single latent-factor explained variation in performance on both the silent film and strange stories task (in Sample 1 and 2) and test performance was sensitive to age-related differences and individual differences within each age-group. A deep learning neural network automated scoring system trained on Sample 1 exhibited interrater reliability and measurement invariance with manual ratings in Sample 2. Validity of ratings from the automated scoring system was supported by unique positive associations between ToM and teacher-rated social competence. The results demonstrate that reliable and valid measures of ToM can be obtained using the new freely available deep learning neural network automated scoring system to rate open-ended text responses. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Mind-mindedness in new mothers and fathers: Stability and discontinuity from pregnancy to toddlerhood

This study examined the development of caregiver mind-mindedness-defined as the propensity to see one's child as an agent with an independent mind-across the first 1,000 days of life. At four time-points (i.e., third trimester of pregnancy, 4, 14, and 24 months postpartum), 384 first-time mothers (M_age = 32.55, SD = 3.63 years) and fathers (M_age = 33.96, SD = 4.40 years) gave 5-minute speech samples about their infant that were coded for mind-mindedness (Meins & Fernyhough, 2015). Reflecting the local population, the 192 heterosexual couples were highly educated (84.6% of mothers, 77.1% of fathers had a degree) and ethnically homogenous (92.7% of mothers, 94.8% of fathers identified as White British). Results showed significant variability in mind mindedness within both expectant mothers and expectant fathers, with no mean group difference. Auto-regressive models demonstrated modest positive associations between prenatal and postnatal mind-mindedness. Latent change score models showed gains in mean mind-mindedness over time that, on average, were stronger for mothers than for fathers. For fathers, gains in mind-mindedness were positively associated with having an infant daughter and infant surgency. For mothers, higher socioeconomic status and more equal childcare were associated with greater gains in mind-mindedness across toddlerhood. Within-couple associations were evident for changes in mind-mindedness, but not for initial (prenatal) scores. We apply the relational account of mind-mindedness to frame our discussion of these findings that, by highlighting both developmental stability and change in mind-mindedness, suggest fruitful avenues for future research. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Mothers' and fathers' executive function both predict emergent executive function in toddlerhood

There are multivariate influences on the development of children's executive function throughout the lifespan and substantial individual differences can be seen as early as when children are 1 and 2 years of age. These individual differences are moderately stable throughout early childhood, but more research is needed to better understand their origins. To some degree, individual differences in executive function are correlated between mother and child, but no research to date has examined these associations prior to when children are preschool age, nor have any studies considered the role of fathers' and mothers' executive function in tandem. Here, we use a sample of 484 families (Mothers 89.2% white; Fathers 92.5% white) in three countries (UK, USA, Netherlands) to investigate the role of each parents' executive function on the development of children's (49.7% female) executive function from 14 (M = 14.42, SD = 0.57) to 24 (M = 24.47, SD = 0.78) months, as well as parenting practices that underlie these associations. Results of structural equation models suggest stability in some-but not all-components of executive function and growing unity between components as children age. We replicate extant findings such that mothers' executive function predicts children's executive function over and above stability and extend these findings to include associations between father and child skills. We find an additive role of fathers' EF, similar in magnitude to the role of mothers' EF. Finally, for both mothers and fathers we find that sensitivity and autonomy supportive practices mediate the relations between parents' and children's executive function.

Reading fiction and reading minds in early adolescence: A longitudinal study

Reading fiction is argued to have benefits for our understanding of others' thoughts, feelings and desires, referred to as 'theory of mind'(ToM). We aimed to test this assumption by examining whether children's reading experience is longitudinally associated with later ToM. We examined reading experience and ToM in 236 children between the ages of 11-13 years. Participants were asked to report on their time spent reading both fiction and non-fiction at ages 11 and 13, ToM was measured at age 13. Verbal ability, reading comprehension, and reading motivation were included as control variables in all analyses. Results showed that children's self-reported fiction, but not their non-fiction reading was associated with ToM. Further, the association was concurrent but not longitudinal: fiction reading and ToM at age 13 were associated but fiction reading at age 11 did not predict ToM at age 13. Our findings motivate further research on what types of reading materials might be beneficial, and the level of exposure to fiction that is needed for measurable benefits for later ToM.

Theory of Mind and Peer Attachment in Adolescence

A growing body of research on theory of mind (ToM) highlights its significance for childhood social outcomes. Extending the developmental scope of this work, the current study investigated links between advanced ToM abilities and peer attachment in adolescence. Polish adolescents (16 to 18 years old; N = 302; 57.6% girls) completed two advanced ToM measures and reported on their peer attachment. With the effects of age and language controlled, girls scored higher than boys for both advanced ToM and peer attachment. However, the association between these measures was only significant in boys. These results are discussed in terms of theory and research on gender-specific approaches to social cognitive development in adolescence.

Willing and able? Theory of mind, social motivation, and social competence in middle childhood and early adolescence

This study investigated the links between theory of mind, social motivation, and children's social competence in middle childhood and early adolescence. Two hundred and sixty four children (136 girls, 128 boys) aged between 8 and 13 years (M Age = 10.88 years, SD = 1.45) completed theory-of-mind tests and self-report questionnaires measuring social motivation. Teachers rated children's social competence at school. Teacher-rated social competence was associated with individual differences in both theory of mind and children's motivation to develop and maintain social relationships. Results suggest that while individual differences in social motivation and theory of mind are partially overlapping, both theory of mind ability and social motivation contribute to successful social interaction at school.

Childhood intellectual disability and parents' mental health: integrating social, psychological and genetic influences

BACKGROUND

Intellectual disability has a complex effect on the well-being of affected individuals and their families. Previous research has identified multiple risk and protective factors for parental mental health, including socioeconomic circumstances and child behaviour.

AIMS

This study explored whether genetic cause of childhood intellectual disability contributes to parental well-being.

METHOD

Children from across the UK with intellectual disability due to diverse genetic causes were recruited to the IMAGINE-ID study. Primary carers completed the Development and Well-being Assessment, including a measure of parental distress (Everyday Feeling Questionnaire). Genetic diagnoses were broadly categorised into aneuploidy, chromosomal rearrangements, copy number variants (CNVs) and single nucleotide variants.

RESULTS

Compared with the UK general population, IMAGINE-ID parents (n = 888) reported significantly elevated emotional distress (Cohen's d = 0.546). Within-sample variation was related to recent life events and the perceived impact of children's difficulties. Impact was predicted by child age, physical disability, autistic characteristics and other behavioural difficulties. Genetic diagnosis also predicted impact, indirectly influencing parental well-being. Specifically, CNVs were associated with higher impact, not explained by CNV inheritance, neighbourhood deprivation or family structure.

CONCLUSIONS

The mental health of parents caring for a child with intellectual disability is influenced by child and family factors, converging on parental appraisal of impact. We found that genetic aetiologies, broadly categorised, also influence impact and thereby family risks. Recognition of these risk factors could improve access to support for parents, reduce their long-term mental health needs and improve well-being of individuals with intellectual disability.

Screen Time and Executive Function in Toddlerhood: A Longitudinal Study

Technology is pervasive in homes with young children. Emerging evidence that electronic screen-based media use has adverse effects on executive functions may help explain negative relations between media use and early academic skills. However, longitudinal investigations are needed to test this idea. In a sample of 193 British toddlers tracked from age 2 to 3 years, we test concurrent and predictive relations between screen use and children’s executive function. We find no concurrent association between screen use and executive function; however, screen time at age 2 is negatively associated with the development of executive functions in toddlerhood from age 2 to 3, controlling for a range of covariates including verbal ability. Implications for parenting, education, and pediatric recommendations are discussed.

Understanding the terrible twos: A longitudinal investigation of the impact of early executive function and parent-child interactions

Impairments in both executive function and parent-child interactions are associated with child externalizing behavior, but few studies have tested the uniqueness of these associations in the first years of life. Addressing these gaps, the current study involved an international sample (N = 438; 218 boys) who, at 14 and 24 months, completed an innovative battery of executive function tasks and were filmed at home in dyadic interaction with their mothers, enabling detailed observational ratings of maternal support. In addition, parents rated infant temperament at 4 months and externalizing behavior at 14 and 24 months. Cross-lagged longitudinal analysis showed a unidirectional developmental association between executive function at 14 months and externalizing behavior at 24 months. In addition, infant negative affect moderated the inverse association between maternal support at 14 months and externalizing behavior at 24 months. The benefits of maternal support were only evident for children with low levels of negative affect in infancy. We discuss this finding in relation to theoretical models that highlight child effects (e.g. models of vantage sensitivity).

Couples becoming parents: Trajectories for psychological distress and buffering effects of social support

BACKGROUND

Becoming a parent is a time of both joy and stress. Associations between exposure to postnatal depression and negative child outcomes underscore the importance of understanding trajectories and correlates of perinatal depression and anxiety.

METHODS

In a study of 438 expectant couples (from the UK, USA and Netherlands) tracked across four time-points (third trimester, 4, 14 and 24 months), we used dyadic latent growth curve modeling (LGCM) of self-reported symptoms of anxiety and depression (CES-D, GHQ, STAI) to investigate the affective impact of becoming a parent.

RESULTS

Confirmatory factor analyses of anxious-depressive symptoms revealed a single latent factor with measurement invariance across time and parent. Dyadic LGCM intercepts showed greater prenatal problems in mothers compared with fathers. LGCM slopes revealed stable maternal problems but worsening paternal problems. Both intercepts and slopes showed significant within-couple associations. Controlling for prenatal salivary cortisol levels and perinatal couple relationship quality, support from friends attenuated mothers' psychological distress and support from family reduced fathers' psychological distress across the transition to parenthood.

LIMITATIONS

Our sample was low risk (i.e., predominantly well-educated and affluent and no history of serious mental illness), limiting the generalizability of findings. In addition, the inverse association between psychological distress and social support may, in part, reflect the use of self-report for both measures.

CONCLUSIONS

The international dyadic longitudinal design strengthens conclusions regarding variation in trajectories of psychological distress in both mothers and fathers. Crucially, social support appears pivotal in enabling new parents to flourish.

Infant screen exposure links to toddlers' inhibition, but not other EF constructs: A propensity score study

Technology is pervasive in homes of families with young children, despite evidence for negative associations between infant exposure to screen-based media and cognitive development that has led the American Academy of Pediatrics (AAP) to discourage parents from exposing children under the age of 18 months to any kind of screen time (AAP, 2016). Here, we apply a propensity score matching approach to estimate relations between electronic screen-based media use in infancy and executive function in early toddlerhood. In an international sample of 416 firstborn infants, parental report of regular exposure to screen-based media at 4 months predicted poorer performance on a test of inhibition at 14 months, but was unrelated to either cognitive flexibility or working memory at 14 months. Results of this study are therefore consistent with the view that early exposure to screen-based media adversely affects the development of executive function.

Measuring and Predicting Individual Differences in Executive Functions at 14 Months: A Longitudinal Study

This study of 195 (108 boys) children seen twice during infancy (Time 1: 4.12 months; Time 2: 14.42 months) aimed to investigate the associations between and infant predictors of executive function (EF) at 14 months. Infants showed high levels of compliance with the EF tasks at 14 months. There was little evidence of cohesion among EF tasks but simple response inhibition was related to performance on two other EF tasks. Infant attention (but not parent-rated temperament) at 4 months predicted performance on two of the four EF tasks at 14 months. Results suggest that EF skills build on simpler component skills such as attention and response inhibition.

Autonomy support in toddlerhood: Similarities and contrasts between mothers and fathers

Infant exploration often hinges on parental autonomy support (i.e., parental behaviors that support children's goals, interests, and choices), a construct that is widely applied in family studies of school-age children and adolescents but less studied in infants and toddlers. Notable gaps concern the equivalence, similarities, and contrasts between mothers' and fathers' autonomy support and the correlates of individual differences in autonomy support. To address these underresearched topics, we conducted parallel home-based structured play observations of 195 infants (Mage = 14.42 months, SD = .59) in dyadic interaction with mothers and fathers. Confirmatory factor analyses demonstrated measurement invariance across parent gender, enabling comparisons that revealed significantly moderately higher levels of autonomy support in mothers than in fathers. Individual differences in autonomy support were unrelated to either parental personality or child temperament, highlighting the potential importance of dyadic characteristics. Consistent with this view, whereas maternal autonomy support did not differ by child gender, fathers with sons displayed less autonomy support than did fathers with daughters. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Does Parental Mind-Mindedness Account for Cross-Cultural Differences in Preschoolers' Theory of Mind?

This study of 241 parent-child dyads from the United Kingdom (N = 120, Mage  = 3.92, SD = 0.53) and Hong Kong (N = 121, Mage  = 3.99, SD = 0.50) breaks new ground by adopting a cross-cultural approach to investigate children's theory of mind and parental mind-mindedness. Relative to the Hong Kong sample, U.K. children showed superior theory-of-mind performance and U.K. parents showed greater levels of mind-mindedness. Within both cultures parental mind-mindedness was correlated with theory of mind. Mind-mindedness also accounted for cultural differences in preschoolers' theory of mind. We argue that children's family environments might shed light on how culture shapes children's theory of mind.

School readiness in children with special educational needs and disabilities: Psychometric findings from a new screening tool, the Brief Early Skills, and Support Index

BACKGROUND

There is an urgent need to accelerate the detection of special educational needs and disabilities (SEND). A recent brief questionnaire designed for teachers and nursery staff, the Brief Early Skills and Support Index (BESSI), shows promising psychometric properties (Hughes, Daly, Foley, White, & Devine, . British Journal of Educational Psychology, 85(3), 332-356.), but has yet to be evaluated as a tool for detecting children who may have SEND.

AIMS

Addressing this gap, this study aimed to assess whether BESSI scores (i) show measurement invariance across SEND status; (ii) show unique associations with SEND status; and (iii) are sensitive and specific to SEND status.

SAMPLE

Eighty-four teachers and nursery staff completed BESSI ratings for 2106 British children aged 2.5-5.5 years (48.9% male, 20% ethnic minority, 9.3% with a statement of SEND).

METHOD

We applied multilevel confirmatory factor analyses, regression analyses, and ROC analyses to examine each of the study questions, using the BESSI subscales (Behavioural Adjustment, Language and Cognition, Daily Living Skills, and Family Support) as dependent variables.

RESULTS

The four BESSI subscales were reliable and showed measurement invariance across SEND status. Over and above effects of age, gender, family income, ethnicity, and family size, SEND status predicted substantial unique variance in BESSI scores. ROC analyses showed that in detecting children identified as having SEND, a cut-off score of 8.50 on the BESSI total score produced good levels of sensitivity and specificity; gender-specific analyses indicated a lower cut-off score of 6.50 for girls.

CONCLUSION

The BESSI appears to be a useful tool in screening children for more detailed assessment of SEND.

Let's Talk: Parents' Mental Talk (Not Mind-Mindedness or Mindreading Capacity) Predicts Children's False Belief Understanding

Although one might expect parents' mind-mindedness (MM; the propensity to view children as mental agents) to relate to everyday mental-state talk (MST) and theory-of-mind capacity, evidence to support this view is lacking. In addition, both the uniqueness and the specificity of relations between parental MM, parental MST, and children's false belief understanding (FBU) are open to question. To address these three gaps, this study tracked 117 preschoolers (60 boys) and their parents across a 13-month period (M_age  = 3.94 years, SD = 0.53, at Time 1). Parental MM, MST, and theory-of-mind capacity showed little overlap. Both MM and MST were weakly associated with children's concurrent FBU, but in line with social constructivist accounts, only MST predicted later FBU.

Family support and gains in school readiness: A longitudinal study

BACKGROUND

Traditional measures of school readiness are labour-intensive and do not assess family support.

AIMS

The current study used the newly developed Brief Early Skills and Support Index (BESSI: Hughes, Daly, Foley, White and Devine 2015) to examine 6-month longitudinal stability and change in teachers' ratings of young children's school readiness and investigate the role of family support as a predictor of school readiness.

SAMPLE

Five hundred and seventy-eight children (270 boys; 74.2% White British) were included at Time 1 aged 2.58-5.84 years (M_age  = 3.98 years, SD = 0.66).

METHOD

Teachers and nursery workers completed BESSI questionnaires for each participant on two occasions separated by 6 months.

RESULTS

The four latent factors of the BESSI (i.e., Behavioural Adjustment, Language and Cognition, Daily Living Skills and Family Support) exhibited longitudinal measurement invariance and individual differences in ratings on each factor showed strong stability over time. BESSI ratings were also sensitive to improvements over time. Auto-regressive models showed that family support and family income (as measured by eligibility for pupil premium support) at Time 1 each uniquely predicted child outcomes at Time 2.

CONCLUSIONS

These findings highlight the importance of family contexts for children's school readiness.

For Better or for Worse? Positive and Negative Parental Influences on Young Children's Executive Function

Despite rapidly growing research on parental influences on children's executive function (EF), the uniqueness and specificity of parental predictors and links between adult EF and parenting remain unexamined. This 13-month longitudinal study of 117 parent-child dyads (60 boys; M_age at Time 1 = 3.94 years, SD = 0.53) included detailed observational coding of parent-child interactions and assessed adult and child EF and child verbal ability (VA). Supporting a differentiated view of parental influence, negative parent-child interactions and parental scaffolding showed unique and specific associations with child EF, whereas the home learning environment and parental language measures showed global associations with children's EF and VA.

Executive Function Mediates the Relations between Parental Behaviors and Children's Early Academic Ability

The past decade has witnessed a growth of interest in parental influences on individual differences in children's executive function (EF) on the one hand and in the academic consequences of variation in children's EF on the other hand. The primary aim of this longitudinal study was to examine whether children's EF mediated the relation between three distinct aspects of parental behavior (i.e., parental scaffolding, negative parent-child interactions, and the provision of informal learning opportunities) and children's academic ability (as measured by standard tests of literacy and numeracy skills). Data were collected from 117 parent-child dyads (60 boys) at two time points ~1 year apart (M Age at Time 1 = 3.94 years, SD = 0.53; M Age at Time 2 = 5.11 years, SD = 0.54). At both time points children completed a battery of tasks designed to measure general cognitive ability (e.g., non-verbal reasoning) and EF (e.g., inhibition, cognitive flexibility, working memory). Our models revealed that children's EF (but not general cognitive ability) mediated the relations between parental scaffolding and negative parent-child interactions and children's early academic ability. In contrast, parental provision of opportunities for learning in the home environment was directly related to children's academic abilities. These results suggest that parental scaffolding and negative parent-child interactions influence children's academic ability by shaping children's emerging EF.

Relations between false belief understanding and executive function in early childhood: a meta-analysis

The association between executive function (EF) and theory of mind (ToM) has been hotly debated for 20 years. Competing accounts focus on: task demands, conceptual overlap, or functional ties. Findings from this meta-analytic review of 102 studies (representing 9,994 participants aged 3-6 years) indicate that the moderate association between EF and one key aspect of ToM, false belief understanding (FBU) is: (a) similar for children from different cultures, (b) largely consistent across distinct EF tasks, but varies across different types of false belief task, and (c) is asymmetric in that early individual differences in EF predict later variation in FBU but not vice versa. These findings support a hybrid emergence-expression account and highlight new directions for research.

Silent films and strange stories: theory of mind, gender, and social experiences in middle childhood

In this study of two hundred and thirty 8- to 13-year-olds, a new "Silent Films" task is introduced, designed to address the dearth of research on theory of mind in older children by providing a film-based analogue of F. G. E. Happé's (1994) Strange Stories task. Confirmatory factor analysis showed that all items from both tasks loaded onto a single theory-of-mind latent factor. With effects of verbal ability and family affluence controlled, theory-of-mind latent factor scores increased significantly with age, indicating that mentalizing skills continue to develop through middle childhood. Girls outperformed boys on the theory-of-mind latent factor, and the correlates of individual differences in theory of mind were gender specific: Low scores were related to loneliness in girls and to peer rejection in boys.

Personal dose equivalent conversion coefficients for neutron fluence over the energy range of 20-250 MeV

Monte Carlo simulations were performed to extend existing neutron personal dose equivalent fluence-to-dose conversion coefficients to an energy of 250 MeV. Presently, conversion coefficients, H(p,slab)(10,alpha)/Phi, are given by ICRP-74 and ICRU-57 for a range of angles of radiation incidence (alpha = 0, 15, 30, 45, 60 and 75 degrees ) in the energy range from thermal to 20 MeV. Standard practice has been to base operational dose quantity calculations <20 MeV on the kerma approximation, which assumes that charged particle secondaries are locally deposited, or at least that charged particle equilibrium exists within the tally cell volume. However, with increasing neutron energy the kerma approximation may no longer be valid for some energetic secondaries such as protons. The Los Alamos Monte Carlo radiation transport code MCNPX was used for all absorbed dose calculations. Transport models and collision-based energy deposition tallies were used for neutron energies >20 MeV. Both light and heavy ions (HIs) (carbon, nitrogen and oxygen recoil nuclei) were transported down to a lower energy limit (1 keV for light ions and 5 MeV for HIs). Track energy below the limit was assumed to be locally deposited. For neutron tracks <20 MeV, kerma factors were used to obtain absorbed dose. Results are presented for a discrete set of angles of incidence on an ICRU tissue slab phantom.

Characterization of neutron reference fields at US Department of Energy calibration fields

The Health Physics Measurements Group at the Los Alamos National Laboratory (LANL) has initiated a study of neutron reference fields at selected US Department of Energy (DOE) calibration facilities. To date, field characterisation has been completed at five facilities. These fields are traceable to the National Institute for Standards and Technology (NIST) through either a primary calibration of the source emission rate or through the use of a secondary standard. However, neutron spectral variation is caused by factors such as room return, scatter from positioning tables and fixtures, source anisotropy and spectral degradation due to source rabbits and guide tubes. Perturbations from the ideal isotropic point source field may impact the accuracy of instrument calibrations. In particular, the thermal neutron component of the spectrum, while contributing only a small fraction of the conventionally true dose, can contribute a significant fraction of a dosemeter's response with the result that the calibration becomes facility-specific. A protocol has been developed to characterise neutron fields that relies primarily on spectral measurements with the Bubble Technology Industries (BTI) rotating neutron spectrometer (ROSPEC) and the LANL Bonner sphere spectrometer. The ROSPEC measurements were supplemented at several sites by the BTI Simple Scintillation Spectrometer probe, which is designed to extend the ROSPEC upper energy range from 5 to 15 MeV. In addition, measurements were performed with several rem meters and neutron dosemeters. Detailed simulations were performed using the LANL MCNPX Monte Carlo code to calculate the magnitude of source anisotropy and scatter factors.

CHELSI: a portable neutron spectrometer for the 20-800 MeV region

CHELSI is a CsI-based portable spectrometer being developed at Los Alamos National Laboratory for use in high-energy neutron fields. Based on the inherent pulse shape discrimination properties of CsI(Tl), the instrument flags charged particle events produced via neutron-induced spallation events. Scintillation events are processed in real time using digital signal processing and a conservative estimate of neutron dose rate is made based on the charged particle energy distribution. A more accurate dose estimate can be made by unfolding the 2D charged particle versus pulse height distribution to reveal the incident neutron spectrum from which dose is readily obtained. A prototype probe has been assembled and data collected in quasi-monoenergetic fields at The Svedberg Laboratory (TSL) in Uppsala as well as at the Los Alamos Neutron Science Center (LANSCE). Preliminary efforts at deconvoluting the shape/energy data using empirical response functions derived from time-of-flight measurements are described.

Operational specifications of the laser illuminated track etch scattering dosemeter reader

The personnel dosimetry operations team at the Los Alamos National Laboratory (LANL) has accepted the laser illuminated track etch scattering (LITES) dosemeter reader into its suite of radiation dose measurement instruments. The LITES instrument transmits coherent light from a He-Ne laser through the pertinent track etch foil and a photodiode measures the amount of light scattered by the etched tracks. A small beam stop blocks the main laser light, while a lens refocuses the scattered light into the photodiode. Three stepper motors in the current LITES system are used to position a carousel that holds 36 track etch dosemeters (TEDs). Preliminary work with the LITES system demonstrated the device had a linear response in counting foils subjected to exposures up to 50 mSv (5.0 rem). The United States Department of Energy requires that the annual general employee dose not exceed 50 mSv (5.0 rem). On a regular basis, LANL uses the Autoscan-60 reader system (Thermo Electron Corp.) for counting track etch dosemeters. However, LANL uses a 15 h etch process for CR-39 dosemeters, and this produces more and larger track etch pits than the 6 h etch used by many institutions. Therefore, LANL only uses the Autoscan-60 for measuring neutron dose equivalent up to exposure levels of approximately 3 mSv (300 mrem). The LITES system has a measured lower limit of detection of approximately 0.6 mSv (60 mrem), and it has a correlation coefficient of R (2) = 0.99 over an exposure range up to 500 mSv (50.0 rem). A series of blind studies were done using three methods: the Autoscan-60 system, manual counting by optical microscope and the LITES instrument. A collection of track etch dosemeters of unknown neutron dose equivalent (NDE) were analysed using the three methods, and the performance coefficient (PC) was calculated when the NDE became known. The Autoscan-60 and optical microscope methods had a combined PC = 0.171, and the LITES instrument had a PC = 0.194, where a PC less than or equal to 0.300 is considered satisfactory.

Monte Carlo modelling of a simple accident dosemeter

A simple dosemeter made of a sulphur tablet, bare and cadmium-covered indium foils and a cadmium-covered copper foil has been modelled using MCNP5. Studies of the model without phantoms or other confounding factors have shown that the cross sections and fluence-to-dose factors generated by the Monte Carlo method agree with those generated by analytic expressions for the high-energy component. In this study, the effect of location on phantoms is studied and an extension of this study to low and intermediate energies is done. The activities expected from exposure to four critical assemblies on phantom is calculated and compared with observations.

Monte Carlo modelling of a simple accident dosemeter

A simple dosemeter made of a sulphur tablet, bare and cadmium-covered indium foils and a cadmium-covered copper foil has been modelled using MCNP5. Studies of the model without phantom or other confounding factors have shown that the cross sections and fluence-to-dose factors generated by the Monte Carlo method agree with those generated by analytic expressions for the high energy component. In this study, a comparison of the effect of location on phantoms and an extension to low and intermediate energies is done. The activities expected from exposure to four critical assemblies on phantom is calculated and compared with observations.

Multisphere default spectra--solution spectrum and dosemeter response implications

Initial calibration of a multisphere spectroscopy system has been completed at Los Alamos National Laboratory using four standard calibration scenarios. Spectrum unfolding was performed using three methods of constructing the default spectrum: simple parameter models, Monte Carlo calculations and physical measurement. Comparisons of the resulting spectra for each solution method are presented. Implications of the spectral solutions upon dosemeter characterisation are addressed.

Computation of cross sections and dose conversion factors for criticality accident dosimetry

In the application of criticality accident dosemeters the cross sections and fluence-to-dose conversion factors have to be computed. The cross section and fluence-to-dose conversion factor for the thermal and epi-thermal contributions to neutron dose are well documented; for higher energy regions (>100 keV) these depend on the spectrum assumed. Fluence is determined using threshold detectors. The cross sections require the folding of an expected spectrum with the reaction cross sections. The fluence-to-dose conversion factors also require a similar computation. The true and effective thresholds are used to include the information on the expected spectrum. The spectra can either be taken from compendia or measured at the facility at which the exposures are to be expected. The cross sections can be taken from data computations or analytic representations and the fluence-to-dose conversion factors are determined by various standards making bodies. The problem remaining is the method of computation. The purpose of this paper is to compare two methods for computing these factors: analytic and Monte Carlo.

Using operational equipment to read accident dosemeters

Analysis of accident dosemeters usually involves the use of laboratory-based counting equipment. Gamma spectrometers are used for indium, copper and gold, and alpha-beta detectors for sulphur. This equipment is usually not easily transported due to the shielding required and the weight and delicacy of the counters. For intercomparison studies that require reading the dosemeters on site, a transportable system is required unless the site operating the study can count samples for all the participants. In the case of an actual accident these systems would have a difficulty in counting a large number of accident dosemeters. In an accident, personnel are usually subdivided according to their level of exposure. Those exposed to higher doses are treated immediately. An alternate system should be made available to handle the dosemeters worn by those personnel are likely to receive lower doses. Improvements in portable operational equipment for gamma and beta monitoring allow their use as spectrometers. Such a system was used for the SILENE intercomparison conducted at IRSN Valduc on 12 June and 19, 2002, and the preliminary results compared well with the other participants.

Laser illuminated etched track scattering (LITES) dosimetry system

Los Alamos National Labs (LANL) has developed an etched track foil (CR-39) reader for neutron dose between 0 and 50.0 mSv. Currently, the US Department of Energy mandates general employee annual exposure not to exceed 50.0 mSv (5 rem). At LANL, due to a non-linear response at higher exposures. accepted practice only uses an Autoscan 60 system up to 3 mSv. The LITES system, however, has demonstrated linear response to 50 mSv, where the proprietary design measures the amount of laser light scattered by the etched tracks, proportional to dose. A collection of calibrated foils was counted by an Autoscan 60 and the LITES prototype, and the Autoscan 60 showed good linearity when counting exposure up to about 15 mSv, but not for higher exposures. From 0 to 50 mSv, the Autoscan 60 had a correlation coefficient of R2 = 0.941 and the LITES system had R2 = 0.991.

WENDI: an improved neutron rem meter

Neutron rem meters are routinely used for real-time field measurements of neutron dose equivalent where neutron spectra are unknown or poorly characterized. These meters are designed so that their response per unit fluence approximates an appropriate fluence-to-dose conversion function. Typically, a polyethylene moderator assembly surrounds a thermal neutron detector, such as a BF3 counter tube. Internal absorbers may also be used to further fine-tune the detector response to the shape of the desired fluence conversion function. Historical designs suffer from a number of limitations. Accuracy for some designs is poor at intermediate energies (50 keV-250 keV) critical for nuclear power plant dosimetry. The well-known Andersson-Braun design suffers from angular dependence because of its lack of spherical symmetry. Furthermore, all models using a pure polyethylene moderator have no useful high-energy response, which makes them inaccurate around high-energy accelerator facilities. This paper describes two new neutron rem meter designs with improved accuracy over the energy range from thermal to 5 GeV. The Wide Energy Neutron Detection Instrument (WENDI) makes use of both neutron generation and absorption to contour the detector response function. Tungsten or tungsten carbide (WC) powder is added to a polyethylene moderator with the expressed purpose of generating spallation neutrons in tungsten nuclei and thus enhance the high-energy response of the meter beyond 8 MeV. Tungsten's absorption resonance structure below several keV was also found to be useful in contouring the meter's response function. The WENDI rem meters were designed and optimized using the Los Alamos Monte Carlo codes MCNP, MCNPX, and LAHET. A first generation prototype (WENDI-I) was built in 1995 and its testing was completed in 1996. This design placed a BF3 counter in the center of a spherical moderator assembly, whose outer shell consisted of 30% by weight WC in a matrix of polyethylene. A borated silicone rubber (5% boron by weight) absorber covered an inner polyethylene sphere to control the meter's response at intermediate energies. A second generation design (WENDI-II) was finalized and tested in 1999. It further extended the high-energy response beyond 20 MeV, increased sensitivity, and greatly facilitated the manufacturing process. A 3He counter tube is located in the center of a cylindrical polyethylene moderator assembly. Tungsten powder surrounds the counter tube at an inner radius of 4 cm and performs the double duty of neutron generation above 8 MeV and absorption below several keV. WENDI-II is suitable for field use as a portable rem meter in a variety of work place environments, and has been recently commercialized under license by Eberline Instruments, Inc. and Ludlum Measurements, Inc. Sensitivity is about a factor of 12 higher than that of the Hankins Modified Sphere (Eberline NRD meter) in a bare 252Cf field. Additionally, the energy response for WENDI-II closely follows the contour of the Ambient Dose Equivalent per unit fluence function [H'(10)/phi] above 0.1 MeV. Its energy response at 500 MeV is approximately 15 times higher than that of the Hankins and Andersson-Braun meters. Measurements of the energy and directional response of the improved meter are presented and the measured response function is shown to agree closely with the predictions of the Monte Carlo simulations in the range from 0.144 MeV to 19 MeV.