Problematic standard errors and confidence intervals for skewness and kurtosis

Many statistics packages print skewness and kurtosis statistics with estimates of their standard errors. The function most often used for the standard errors (e.g., in SPSS) assumes that the data are drawn from a normal distribution, an unlikely situation. Some textbooks suggest that if the statistic is more than about 2 standard errors from the hypothesized value (i.e., an approximate value for the critical value from the t distribution for moderate or large sample sizes when α = 5%), the hypothesized value can be rejected. This is an inappropriate practice unless the standard error estimate is accurate and the sampling distribution is approximately normal. We show distributions where the traditional standard errors provided by the function underestimate the actual values, often being 5 times too small, and distributions where the function overestimates the true values. Bootstrap standard errors and confidence intervals are more accurate than the traditional approach, although still imperfect. The reasons for this are discussed. We recommend that if you are using skewness and kurtosis statistics based on the 3^rd and 4^th moments, bootstrapping should be used to calculate standard errors and confidence intervals, rather than using the traditional standard. Software in the freeware R for this article provides these estimates.     

Valence resolution of ambiguous facial expressions using an emotional oddball task

Previous research suggests that neural and behavioral responses to surprised faces are modulated by explicit contexts (e.g., "He just found $500"). Here, we examined the effect of implicit contexts (i.e., valence of other frequently presented faces) on both valence ratings and ability to detect surprised faces (i.e., the infrequent target). In Experiment 1, we demonstrate that participants interpret surprised faces more positively when they are presented within a context of happy faces, as compared to a context of angry faces. In Experiments 2 and 3, we used the oddball paradigm to evaluate the effects of clearly valenced facial expressions (i.e., happy and angry) on default valence interpretations of surprised faces. We offer evidence that the default interpretation of surprise is negative, as participants were faster to detect surprised faces when presented within a happy context (Exp. 2). Finally, we kept the valence of the contexts constant (i.e., surprised faces) and showed that participants were faster to detect happy than angry faces (Exp. 3). Together, these experiments demonstrate the utility of the oddball paradigm to explore the default valence interpretation of presented facial expressions, particularly the ambiguously valenced facial expression of surprise.     

Sociocultural correlates of compulsive exercise: is the environment important in fostering a compulsivity towards exercise among adolescents?

Sociocultural factors hypothesised to be influential in eating disorders were assessed for their relationship with compulsive exercise. A sample of 828 adolescent boys and girls completed measures assessing sociocultural messages to change body shape as well as pressure to be thin, and also measures of compulsive exercise and disordered eating. Results showed that the sociocultural influences differed slightly between boys and girls. Hierarchical regressions showed that, after controlling for disordered eating and BMI, messages to become more muscular and media pressure to be thin significantly predicted compulsive exercise in boys, while the same regression in girls reported only media pressure to be thin as a significant predictor of compulsive exercise. These findings demonstrate the influence of the media in boys’ and girls’ compulsive exercising, as well as highlight the influence of body shape messages to become more muscular on boys’ compulsive exercise.     

Health Implications of Conflict in Close Relationships

We summarize the large body of research conducted over the previous 30 years on the link between interpersonal conflict and physiological outcomes, with a focus on implications for health. Specifically, we review evidence that conflict in close, romantic relationships affects internal bodily processes, including cardiovascular, endocrine, and immune function, as well as objective health indicators. We focus on studies that have utilized standardized, laboratory‐based conflict discussions, as we believe this methodology provides the clearest picture of how conflict affects health. It is our hope that this general overview serves as a useful introduction to the state of the field.     

Exploring attention-based explanations for some violations of Hick’s law for aimed movements

Choice reaction time generally increases linearly with the logarithm of the number of potential stimulus-response alternatives, a regularity known as Hick's law. Two apparent violations of this generalization, which have been reported for aimed eye movements (Kveraga, Boucher, & Hughes, Experimental Brain Research, 146, 307-314, 2002), and arm movements (Wright, Marino, Belovsky, & Chubb, Experimental Brain Research, 179, 475-496, 2007), occurred when the indicator stimulus was an abrupt change at the location that was the target of the to-be-made movement. We report two experiments that examined and rejected the hypothesis that these abrupt-onset indicator stimuli triggered a shift in exogenous attention and that this led to unusually small uncertainty effects. Each experiment compared this indicator stimulus with a single alternative: Experiment 1 tested an indicator stimulus at all locations other than the target; Experiment 2 tested a central pointer to the target. Neither alternative led to an uncertainty effect for pointing responses that was of the size typically observed for other responses using the same stimuli.     

The Interaction Between Pubertal Timing and Peer Popularity for Boys and Girls: An Integration of Biological and Interpersonal Perspectives on Adolescent Depression

The transition to adolescence marks a time of sharply increased vulnerability to the development of depression, particularly among girls. Past research has examined isolated risk factors from individual theoretical models (e.g., biological, interpersonal, and cognitive) of depression, but few have examined integrative models. This study investigated the conjoint effects of early pubertal timing and popularity in the longitudinal prediction of depressive symptoms. A total of 319 girls and 294 boys (ages 11–14) provided information on their pubertal status, depressive symptoms, and the social status (i.e., popularity) of their peers. Adolescents completed a second measure of depressive symptoms 11 months after the initial time point. Findings supported an integrated biological-interpersonal model in explaining the development of depressive symptoms during adolescence. Early pubertal development was associated with increase in depressive symptoms only when accompanied by low levels of popularity. High levels of popularity buffered the association between early pubertal development and later depressive symptoms. Unexpectedly, these results were significant both for girls and boys. Results are discussed in terms of dynamic systems theories.     

Peer-Nominated Deviant Talk Within Residential Treatment: Individual and Group Influences on Treatment Response

This research examined deviant talk during summer residential treatment using peer nominations and extensive field observations. Participants were 239 youth (M _age = 12.62, SD = 2.60; 67% male), nested in 26 treatment groups. Deviant talk was present in this setting, showed individual differences, and increased over time, especially for younger boys. As expected, its relationship to treatment response was moderated by peer behavior. Initial levels of individual deviant talk were related to clinical improvement, but primarily when peer deviant talk was low. Initial levels of peer deviant talk were related to higher than expected end of treatment aggression, especially for youth who were high in deviant talk. Deviant talk effects were observed for staff impressions of change and observations of aggression and adjustment. Initial antisocial behavior affected whether individual or peer levels of deviant talk more heavily influenced treatment response. Implications for clinical assessment and treatment monitoring are discussed.