Constrained versus unconstrained estimation in structural equation modeling

Recently, R. D. Stoel, F. G. Garre, C. Dolan, and G. van den Wittenboer (2006) reviewed approaches for obtaining reference mixture distributions for difference tests when a parameter is on the boundary. The authors of the present study argue that this methodology is incomplete without a discussion of when the mixtures are needed and show that they only become relevant when constrained difference tests are conducted. Because constrained difference tests can hide important model misspecification, a reliable way to assess global model fit under constrained estimation would be needed. Examination of the options for assessing model fit under constrained estimation reveals that no perfect solutions exist, although the conditional approach of releasing a degree of freedom for each active constraint appears to be the most methodologically sound one. The authors discuss pros and cons of constrained and unconstrained estimation and their implementation in 5 popular structural equation modeling packages and argue that unconstrained estimation is a simpler method that is also more informative about sources of misfit. In practice, researchers will have trouble conducting constrained difference tests appropriately, as this requires a commitment to ignore Heywood cases. Consequently, mixture distributions for difference tests are rarely appropriate.     

Psychobiology of mindfulness

There is controversy about whether mindfulness-based approaches to psychotherapy represent a new wave of cognitive-behavioral therapy or a core process in all psychotherapies. One way of conceptualizing mindfulness is in terms of emotion regulation; mindfulness is a strategy aimed at opposing suppression and avoidance. Dispositional mindfulness has been associated with greater activation in prefrontal cortex and greater deactivation of amygdala during affect labeling. A number of rigorous studies of mindfulness-based cognitive therapy for depression have been positive. However, much remains to be discovered about the underlying mechanisms of and clinical indications for mindfulness-based approaches.     

Cognitive performance and morning levels of salivary cortisol and alpha-amylase in children reporting high vs. low daily stress perception

The aim of the present study was to assess the effects of daily stress perception on cognitive performance and morning basal salivary cortisol and alpha-amylase levels in healthy children aged 9-12. Participants were classified by whether they had low daily perceived stress (LPS, n = 27) or a high daily perceived stress (HPS, n = 26) using the Children Daily Stress Inventory (CDSI). Salivary cortisol and alpha-amylase were measured at awakening and 30 minutes later. Cognitive performance was assessed using the Cognitive Drug Research assessment system. The HPS group exhibited significantly poorer scores on speed of memory (p < .05) and continuity of attention (p < .05) relative to the LPS group. The HPS group also showed significantly lower morning cortisol levels at awakening and at +30 minutes measures in comparison with the LPS group (p < .05), and mean morning cortisol levels were negatively correlated with speed of memory (p < .05) in the 53 participants. No significant differences were observed between both groups in alpha-amylase levels. These findings suggest that daily perceived stress in children may impoverish cognitive performance via its modulating effects on the HPA axis activity.     

Differences in perceptions on sexual and reproductive health between service providers and people living with HIV: a qualitative elicitation study

The sexual and reproductive health (SRH)-related needs of people living with HIV/AIDS (PLHA) have not been sufficiently recognised in research and clinical care. Fifteen study sites in 13 European countries participated in this qualitative study to assess differences in perceptions between service providers (SP) and PLHA on SRH-related problems and needs of PLHA. Factors influencing SRH were determined to collect evidence on how to improve service provision. Qualitative data were obtained using an interpretative ethnographical approach. Data were analysed inductively on country level; a cross country data matrix was developed to facilitate the contextual analysis. Thirty-seven FGD discussions were organised with a total of 254 participants. A short survey was distributed to assess demographic characteristics. Results revealed insufficient information and lack of behavioural skills regarding SRH issues among PLHA. Intra- and interpersonal, provider-related, and social factors were found to influence the SRH behaviours of PLHA. Although from patients' perception SRH is a prioritized issue, it rarely comes up during routine HIV clinical care. SP need adequate counseling training to tackle SRH-related issues. A better integration between HIV care programs and SRH care settings is needed to improve effective service provision.     

Dimensionality of rosenberg’s self-esteem scale among normal-technical stream students in Singapore

Dimensionality of the widely used Rosenberg’s Self-Esteem Scale (RSES) was investigated in a sample of 153 seventh-grade Asian students from Singapore. Confirmatory factor analyses performed on the scores of the RSES revealed two factors (positive and negative self-esteem) as hypothesized. Both factors were empirically related to different external variables. Results from multiple regression analyses indicated that positive self-esteem significantly predicted students’ mastery goal orientation and academic self-efficacy scores while negative self-esteem significantly predicted students’ disruptive behavior. These findings provide some preliminary support that the two factors could possibly be measuring substantively distinct dimensions, thus calling into question the unidimensionalty of the RSES in an Asian school-based sample. This study was supported by a grant from Center for Research in Pedagogy and Practice, National Institute of Education (CRP 26/04 RA) to Rebecca P. Ang.     

Effectiveness of school-based prevention and intervention programs for children and adolescents with emotional disturbance: A meta-analysis

The present study evaluated the effectiveness of school-based prevention and intervention programs for children and adolescents at-risk for and with emotional disturbance. Published outcome studies (k = 29) from December, 1988, to March, 2006, including 1405 children and adolescents were reviewed. Each investigation was coded on several variables describing the child, parent, and teacher samples, as well as reported outcome results. The overall mean weighted effect size was 1.00 at post-test and 1.35 at follow-up. Mean weighted ESs were 0.42 for between-subjects design studies, 0.87 for within-subjects design studies, and 1.87 for single-subject design studies. Prevention programs yielded a mean weighted ES of 0.54 and intervention programs produced a mean weighted ES of 1.35. Findings for specific outcome foci are presented and implications are discussed.     

A semantics-based approach to the "no negative evidence" problem

Previous studies have shown that children retreat from argument-structure overgeneralization errors (e.g., * Don't giggle me ) by inferring that frequently encountered verbs are unlikely to be grammatical in unattested constructions, and by making use of syntax-semantics correspondences (e.g., verbs denoting internally caused actions such as giggling cannot normally be used causatively). The present study tested a new account based on a unitary learning mechanism that combines both of these processes. Seventy-two participants (ages 5–6, 9–10, and adults) rated overgeneralization errors with higher (* The funny man's joke giggled Bart ) and lower (* The funny man giggled Bart ) degrees of direct external causation. The errors with more-direct causation were rated as less unacceptable than those with less-direct causation. This finding is consistent with the new account, under which children acquire—in an incremental and probabilistic fashion—the meaning of particular constructions (e.g., transitive causative = direct external causation) and particular verbs, rejecting generalizations where the incompatibility between the two is too great.     

Combined eyetracking and keystroke-logging methods for studying cognitive processes in text production

Writers typically spend a certain proportion of time looking back over the text that they have written. This is likely to serve a number of different functions, which are currently poorly understood. In this article, we present two systems, ScriptLog+TimeLine and EyeWrite, that adopt different and complementary approaches to exploring this activity by collecting and analyzing combined eye movement and keystroke data from writers composing extended texts. ScriptLog+TimeLine is a system that is based on an existing keystroke-logging program and uses heuristic, pattern-matching methods to identify reading episodes within eye movement data. EyeWrite is an integrated editor and analysis system that permits identification of the words that the writer fixates and their location within the developing text. We demonstrate how the methods instantiated within these systems can be used to make sense of the large amount of data generated by eyetracking and keystroke logging in order to inform understanding of the cognitive processes that underlie written text production.