Human Psychophysical Functions,an Update: Methods for Identifying their form; Estimating their Parameters; and Evaluating the Effects of Important Predictors

Stevens’ power law for the judgments of sensation has a long history in psychology and is used in many psychophysical investigations of the effects of predictors such as group or condition. Stevens’ formulation \(\varPsi = {aP}^{n}\), where \(\varPsi \) is the psychological judgment, P is the physical intensity, and \(n\) is the power law exponent, is usually tested by plotting log \((\varPsi )\) against log (P). In some, but by no means all, studies, effects on the scale parameter, \(a\), are also investigated. This two-parameter model is simple but known to be flawed, for at least some modalities. Specifically, three-parameter functions that include a threshold parameter produce a better fit for many data sets. In addition, direct non-linear computation of power laws often fit better than regressions of log-transformed variables. However, such potentially flawed methods continue to be used because of assumptions that the approximations are “close enough” as to not to make any difference to the conclusions drawn (or possibly through ignorance the errors in these assumptions). We investigate two modalities in detail: duration and roughness. We show that a three-parameter power law is the best fitting of several plausible models. Comparison between this model and the prevalent two parameter version of Stevens’ power law shows significant differences for the parameter estimates with at least medium effect sizes for duration.     

Behavioral and Psychophysiological Effects of a Yoga Intervention on High-Risk Adolescents: A Randomized Control Trial

The purpose of this study was to conduct a pilot randomized control trial to test whether a mindful yoga intervention had a beneficial impact on substance use and its psychological and psychophysiological correlates in high-risk adolescents. Research on yoga has generated growing evidence for its positive effects on physical and emotional health. However, most studies are conducted with adults, with few controlled studies conducted with youth. We designed a 20-session mindful yoga intervention for adolescents attending a school for students at high-risk for dropping out. The 50-min classes were offered three times a week. The participants (mean age = 16.7 years) were randomly assigned to control and intervention groups. Multi-rater (student, teacher), multi-method (survey, cognitive, psychophysiological) data were collected before and after the yoga curriculum. At post-test, students in the yoga condition, as compared to control students, exhibited trends toward decreased alcohol use and improved teacher-rated social skills (p < .10); and showed a non-significant increase in arousal in response to relevant stimuli as measured in skin conductance. Significant effects were not found on hypothesized proximal measures of self-regulation, mood, mindfulness, or involuntary engagement coping. Future research is needed to replicate and expand upon our findings. Studies are also needed with larger samples to further investigate potential mediators and moderators of yoga’s effects.     

Revisiting the mediating role of leader–member exchange in transformational leadership: the differential impact model

Transformational leadership (TFL) has been proposed as an essential antecedent of leader–member exchange (LMX), which in turn affects outcomes in organizations. We extend this mediation hypothesis in two ways by proposing a differential impact model, which we test on three organizational outcomes: employee job satisfaction, employee organizational commitment, and leader effectiveness. First, we extend LMX’s mediational impact—which has previously only been tested for employee outcomes—to leader effectiveness. Second, we argue that this mediation will be stronger for outcomes that are more proximal rather than distal to dyadic relations between leader and followers (high proximity: job satisfaction; medium proximity: organizational commitment; low proximity: leader effectiveness). Meta-analytic structural equation modelling based on 132 studies revealed that LMX mediates TFL’s relationships with employee outcomes (more strongly for job satisfaction than for commitment), but not with leader effectiveness, whereas TFL showed a stronger direct link to leader effectiveness. The findings suggest that TLF and LMX contribute differentially to organizational outcomes depending on their proximity to dyadic relations between leaders and followers. The differential impact model uncovers leadership effectiveness processes, integrates influential leadership theories, and highlights the importance of distinguishing between different outcome measures and the processes facilitating them.     

Menstrual Reactivity: The Role of Gender-Specificity,Anxiety Sensitivity,and Somatic Concerns in Self-Reported Menstrual Distress

To determine the impact of gender roles, anxiety sensitivity, and somatic concerns on self-reported menstrual distress, two studies were conducted. In the first study using 278 primarily Caucasian college females, anxiety-sensitivity level, not current menstrual cycle phase, influenced reports of menstrual symptom severity and depression. Regardless of cycle phase at the time of self-report, women high in anxiety sensitivity reported significantly more depressed mood, trait anxiety, and retrospective menstrual symptoms. In the second study of 158 primarily Caucasian college females varying in anxiety sensitivity levels, adherence to sex role stereotypes, feminist beliefs, and illness attitudes were examined. Participants also completed measures of general premenstrual, most-recent premenstrual, and current menstrual symptoms. Women high in anxiety sensitivity reported the highest levels of sex-specificity, feminist embeddedness, and illness attitudes, with sex-specificity accounting for significant variance in current menstrual symptoms. Results are discussed within the context of the menstrual reactivity hypothesis, which proposes that beliefs surrounding the menstrual cycle and body sensations expectancies contribute to self-reports of greater menstrual distress. Women high in anxiety sensitivity appear to represent one subgroup vulnerable to menstrual reactivity.     

Efficacy of a Brief,School‐Based Bystander Bullying Intervention on High School Students' Alcohol Use

The authors examined the efficacy of a brief bystander bullying intervention on reducing alcohol use among high school students (N = 61). As hypothesized, high‐risk drinkers in the intervention group reported reduced drinking compared with control students at a 30‐day follow‐up.     

Effects of tobacco use on non-adherence to antiretroviral therapy among HIV-positive patients in South Africa

This study aimed to estimate the relationship between tobacco use and non-adherence to antiretroviral therapy (ART) in a South African sample. Participants were 1 963 HIV patients who attended a primary care clinic in Pretoria (female = 68.5%; black African = 99.5%; median age = 37.0 years; tobacco users only = 8.6%, problem drinkers only = 14.9%, and tobacco users and problem drinkers = 10.5%). In adjusted logistic regression analysis, tobacco use only was not significantly associated with non-adherence to ART. Alcohol use only (OR: 1.72; CI: 1.26, 2.36) and tobacco use and problem drinking (OR: 2.31; CI: 1.60, 3.33) were highly associated with non-adherence to ART.     

Functions of Identity in the Context of Being a Student: Development and Validation of the Functions of Student Identity Scale

A promising approach to the understanding of identity is the identity functions framework. However, its developmental specificities associated with adolescence remain unexplored. The aim of this study was to develop and test a new measure of the functions of identity as they relate to being a student. Consistent with the theoretical framework, an exploratory analysis with a subsample of high school students revealed five identity functions. A confirmatory analysis with a second subsample found that a higher-order model incorporating these five subscales demonstrated good fit to the data. A bifactor model and statistical indices indicated that it is appropriate to interpret a total student identity score using this instrument. The five subscales, and total scale, demonstrated good convergent validity with a measure of academic behavioral change. These preliminary results suggest that this new instrument presents good psychometric properties and that it is a suitable assessment instrument for the measurement of students’ processes and outcomes. For example, its associations with academic performance stages of changes suggest that this instrument will be useful for identifying students at risk for poor academic trajectories.