The Metaphysics of Causal Models

This paper presents an attempt to integrate theories of causal processes—of the kind developed by Wesley Salmon and Phil Dowe—into a theory of causal models using Bayesian networks. We suggest that arcs in causal models must correspond to possible causal processes. Moreover, we suggest that when processes are rendered physically impossible by what occurs on distinct paths, the original model must be restricted by removing the relevant arc. These two techniques suffice to explain cases of late pre?mption and other cases that have proved problematic for causal models.

Consistency in infant sleeping arrangements and mother–infant interaction

This study examined the association between infant sleeping arrangements (i.e., habitual co‐sleeping, inconsistent co‐sleeping, and non‐co‐sleeping) and quality of mother–infant interaction during play in a sample of mothers, each with a typically developing infant (N=70). Mother–infant dyads who experienced consistency in infant sleeping arrangements in a typical week at 6 months (i.e., habitual co‐sleeping or non‐co‐sleeping) were characterized by more positive maternal and infant behavior and dyadic quality of interaction at 9 months compared with dyads who experienced inconsistency in sleeping arrangements. Additionally, a greater amount of co‐sleeping per week was associated with an increased duration of breastfeeding, mothers working fewer hours, less infant temperamental intensity, and less maternal depression. This study underscores the advantages of empirically based studies that consider consistency in infant sleep experience as a factor that is associated with more positive mother–child interaction.     

Changes in muscle and joint coordination in learning to direct forces

While it has been suggested that bi-articular muscles have a specialized role in directing external reaction forces, it is unclear how humans learn to coordinate mono- and bi-articular muscles to perform force-directing tasks. Participants were asked to direct pedal forces in a specified target direction during one-legged cycling. We expected that with practice, performance improvement would be associated with specific changes in joint torque patterns and mono- and bi-articular muscular coordination. Nine male participants practiced pedaling an ergometer with only their left leg, and were instructed to always direct their applied pedal force perpendicular to the crank arm (target direction) and to maintain a constant pedaling speed. After a single practice session, the mean error between the applied and target pedal force directions decreased significantly. This improved performance was accompanied by a significant decrease in the amount of ankle angular motion and a smaller increase in knee and hip angular motion. This coincided with a re-organization of lower extremity joint torques, with a decrease in ankle plantarflexor torque and an increase in knee and hip flexor torques. Changes were seen in both mono- and bi-articular muscle activity patterns. The mono-articular muscles exhibited greater alterations, and appeared to contribute to both mechanical work and force-directing. With practice, a loosening of the coupling between bi-articular thigh muscle activation and joint torque co-regulation was observed. The results demonstrated that participants were able to learn a complex and dynamic force-directing task by changing the direction of their applied pedal forces through re-organization of joint torque patterns and mono- and bi-articular muscle coordination.     

Body Satisfaction in Gym-active Males: An Exploration of Sexuality, Gender, and Narcissism

This study compared 80 gay and straight Australian males on self report measures of body satisfaction, masculinity, femininity, narcissism, and reasons for exercising at gyms to explore factors related to excessive exercise. Gay males are less satisfied with their bodies compared to straight males. Improving appearance was more important for gay men, while fun was considered more important for straight men. Only sexual orientation and masculinity contributed independently to body satisfaction. Straight males who scored high on masculinity were most satisfied with their bodies, while gay males who scored low on masculinity were least satisfied with their bodies, irrespective of femininity and narcissism. Hours exercising per week and fun as a reason for exercising, significantly contributed to body satisfaction.     

Culture and social support

Social support is one of the most effective means by which people can cope with stressful events. Yet little research has examined whether there are cultural differences in how people utilize their social support networks. A review of studies on culture and social support presents evidence that Asians and Asian Americans are more reluctant to explicitly ask for support from close others than are European Americans because they are more concerned about the potentially negative relational consequences of such behaviors. Asians and Asian Americans are more likely to use and benefit from forms of support that do not involve explicit disclosure of personal stressful events and feelings of distress. Discussion centers on the potential implications of these findings for intercultural interactions and for the use of mental health services by Asians and Asian Americans. (PsycINFO Database Record (c) 2008 APA, all rights reserved).