Space-time behavior of single and bimanual rhythmical movements: data and limit cycle model

How do space and time relate in rhythmical tasks that require the limbs to move singly or together in various modes of coordination? And what kind of minimal theoretical model could account for the observed data? Earlier findings for human cyclical movements were consistent with a nonlinear, limit cycle oscillator model (Kelso, Holt, Rubin, & Kugler, 1981) although no detailed modeling was performed at that time. In the present study, kinematic data were sampled at 200 samples/second, and a detailed analysis of movement amplitude, frequency, peak velocity, and relative phase (for the bimanual modes, in phase and antiphase) was performed. As frequency was scaled from 1 to 6 Hz (in steps of 1 Hz) using a pacing metronome, amplitude dropped inversely and peak velocity increased. Within a frequency condition, the movement's amplitude scaled directly with its peak velocity. These diverse kinematic behaviors were modeled explicitly in terms of low-dimensional (nonlinear) dissipative dynamics, with linear stiffness as the only control parameter. Data and model are shown to compare favorably. The abstract, dynamical model offers a unified treatment of a number of fundamental aspects of movement coordination and control.     

Individual response patterns and the effects of different behavioral methods in the treatment of claustrophobia

The importance of individual response patterns in claustrophobic patients was examined in the present study. Thirty-four psychiatric outpatients with a phobia of enclosed spaces were assessed in a small test chamber. During the test their overt behavior was video-taped, heart-rate was measured continuously, and self-ratings of experienced anxiety were made at certain intervals. On the basis of their reactions in the test situation, the patients were divided into two groups showing different response patterns—behavioral and physiological reactors. Within each group the patients were randomly assigned to one behaviorally-focused method (exposure), one physiologically-focused method (applied relaxation) and a waiting-list control group. The patients were treated individually in eight sessions. The between-group comparisons showed that both exposure and applied relaxation were significantly better than the waiting-list condition. Furthermore, exposure yielded better results than applied relaxation for the behavioral reactors, while applied relaxation was better than exposure for the physiological reactors. The improvements were maintained at a follow-up assessment 14 months after the end of treatment. The results support the hypothesis that greater effects are achieved when the method used fits the patient's response pattern than when it does not.     

The minimum average correlation between equivalent sets of uncorrelated factors

A simplified proof of a lemma by Ledermann [1938], which lies at the core of the factor indeterminacy issue, is presented. It leads to a representation of an orthogonal matrixT, relating equivalent factor solutions, which is different from Ledermann's [1938] and Guttman's [1955].T is used to evaluate bounds on the average correlation between equivalent sets of uncorrelated factors. It is found that the minimum average correlation is independent of the data.This paper owes much to an unknown reviewer.     

Self-efficacy as a health-protective resource in teachers? A biopsychological approach

OBJECTIVE: To examine the psychobiological correlates of self-efficacy in teachers. DESIGN: Study 1 examined associations between teacher self-efficacy and cardiac activation on a working day and Study 2 assessed the cortisol morning response in teachers with varying levels of teacher self-efficacy. MAIN OUTCOME MEASURES: Teacher self-efficacy was assessed by questionnaire. In Study 1 heart rate, heart rate variability, and locomotor activity were recorded by 22 hours ambulatory monitoring and subjective measures of stress and strain were obtained. Study 2 assessed the cortisol response to awakening to obtain a measure of HPA-axis activation and teachers filled in a questionnaire on physical complaints. RESULTS AND CONCLUSION: Study 1 found that self-efficacy proved protective for psychological well-being. Moreover, after controlling for locomotor activity, demographic, and lifestyle variables, self-efficacy was associated with elevated heart rate and attenuated heart rate variability during school and leisure time, respectively, but not during the night, thus questioning the health-implications of self-efficacy. Study 2 found that teachers high in self-efficacy exhibited an attenuated cortisol response to awakening and fewer cardiac complaints. The results of both studies are compatible with the view that teacher self-efficacy might act as a physiological toughening agent with possibly favorable health outcomes.