Stability and variability may respond differently to changes in walking speed

In gait research it has often been assumed that variability and stability are negatively correlated, where increases in variability are assumed to equate with increases in instability. The purpose of this paper is to illustrate that variability does not always equate with stability. To proof this point, a method was developed to directly assess stability and variability during the application of a visual perturbation at different walking speeds. Walking variability was measured by using the average standard deviation of the knee joint angle across the gait cycle. Walking stability was measured by the recovery time of the knee joint angle trajectory from the distortion induced by a visual perturbation that was delivered at the beginning of the stance phase. Five participants were required to walk at six different velocities on a treadmill (0.67, 0.80, 0.94, 1.07, 1.21, and 1.34 m/s). The coefficients of intraclass correlations for the experiment were 83% and 80% for the calculated stability and variability, respectively. The calculated stabilities were not sensitive to changes in walking speed (p>0.98). The calculated variability however decreased with increases in walking speed (p=0.004). No significant correlation between variability and stability was observed (r=-0.002). We suggest that gait stability is independent of variability during locomotion and should thus be measured independently.     

The myth of a new tolerance for old differences: A rebuttal to meacham

This piece responds to Meacham's (1994) suggestion that prejudice may be replaced by tolerance through the simple understanding of two forms of individualism that may be expressed by members of society—that is, that if we move from a self-contained to an ensembled individualism, we will treat those different from ourselves in a more tolerant fashion. This model is criticized for its emphasis on tolerance of, rather than respect for, all groups in society and, furthermore, for its bias toward groups that are more highly valued by the current society.     

Measuring depressive symptomatology of patients referred to a behavioral medicine clinic: Concordance of self-report measures

We measured depressive symptomatology of 134 outpatient veterans treated within a Behavioral Medicine Clinic utilizing three reliable instruments with depression subscales: Minnesota Multiphasic Personality Inventory (MMPI), Derogatis Stress Profile (DSP), and Symptom Checklist 90—Revised (SCL-90-R). Results indicate that although the instruments correlate significantly, they differ in sensitivity to depression and are clinically discordant. The MMPI classified a substantially higher number of patients as depressed than either the DSP or SCL-90-R. The present study argues that the discrepancy in clinical concordance and sensitivity of the three depression scales has considerable implications for psychologists concerned with the assessment and treatment of depression.     

Stimulus control in a simple instrumental task: The role of internal and external stimuli

Two experiments using rats in a straight alley runway task tested the hypothesis that standard stimuli such as tones and lights (“external” stimuli) and schedule-generated aftereffect stimuli (“internal” stimuli) operate similarly and are similarly subject to the compounding rules specified by R. A. Rescorla and A. R. Wagner (In A. Black & W. Prokasy (Eds.), Classical conditioning II: Current theory and research. New York: Appleton-Century-Crofts, 1972). The experimental task was an instrumental analog of the classic blocking experiment (L. J. Kamin, In M. R. Jones (Ed.). In Experiment 1, blocking of an external discriminative stimulus by a different asymptotic discrimination was accomplished. In Experiment 2, blocking of an internal stimulus discrimination by an asymptotic external stimulus discrimination was obtained. The present results support the view that internal and external stimuli are indeed similar and function in the same manner with regard to blocking of stimulus control.     

Gender-Role Cognition in Three-Year-Old Boys and Girls

Although the multidimensionality of gender roles has been well established, few researchers have investigated male and female roles separately. Because of the substantial differences in the ways male and female roles are portrayed in our culture, boys and girls may think and learn about these roles differently. The male role is more clearly defined, more highly valued, and more salient than the female role; thus, children's cognitions about these two roles may be expected to differ. The present study addressed the question of whether there is sex-typical variation in gender labeling, gender-role knowledge, and schematicity. Participants were 120 families; 15% were from minority ethnic groups, and 17% were single-parent families; 25% of the parents had a high school education or less. Results indicated that at 36 months of age, boys were less able to label gender and less knowledgeable about gender roles than were girls. Boys' knew more about male stereotypes than female stereotypes, whereas girls knew considerably more than boys about the female role and as much as boys about the male role. Boys and girls were found to be similar in gender schematicity. Traditionality of parental attitudes regarding child-rearing and maternal employment were not strongly related to children's gender cognition.     

It's not just what you say,it's how you say it too. Adolescents' hostile attribution of intent and emotional responses to social comments

A highly prevalent and relevant situation in which adolescents have to interpret the intentions of others is when they interact with peers. We therefore successfully introduced a new paradigm to measure hostile attribution bias (HAB) and emotional responses to such social interactions and examined how it related to youth's aggressiveness. We presented 881 adolescents (M_age = 14.35 years; SD = 1.23; 48.1% male) with audio fragments of age-mates expressing social comments that varied in content (e.g., what the person says) and tone of voice (e.g., how the person says it). Participants' peers also reported on their aggressiveness. In general, added negativity of content and tone was driving the youth's intent attribution and emotional responses to the comments. In line with the Social Information Processing model, we found more hostile attribution of intent and more negative emotional responses of aggressive youth to ambiguous stimuli. Aggression was also related to more hostile intent attributions when both content and tone were negative. Unlike most studies on HAB, the aggression effects in the current study emerged for girls, but not boys. Implications of these results and future use of the experimental paradigm are discussed.     

Differences in postural control and movement performance during goal directed reaching in children with developmental coordination disorder

Poor upper-limb coordination is a common difficulty for children with developmental coordination disorder (DCD). One hypothesis is that deviant muscle timing in proximal muscle groups results in poor postural and movement control. The relationship between muscle timing, arm motion and children's upper-limb coordination deficits has not previously been studied. The aim of this study was to investigate the relationship between functional difficulties with upper-limb motor skills and neuromuscular components of postural stability and coordination. Sixty-four children aged 8-10 years, 32 with DCD and 32 without DCD, participated in the study. The study investigated timing of muscle activity and resultant arm movement during a rapid, voluntary, goal-directed arm movement. Results showed that compared to children without DCD, children with DCD took significantly longer to respond to visual signals and longer to complete the goal-directed movement. Children with DCD also demonstrated altered activity in postural muscles. In particular, shoulder muscles, except for serratus anterior, and posterior trunk muscles demonstrated early activation. Further, anterior trunk muscles demonstrated delayed activation. In children with DCD, anticipatory function was not present in three of the four anterior trunk muscles. These differences support the hypothesis that in children with DCD, altered postural muscle activity may contribute to poor proximal stability and consequently poor arm movement control when performing goal-directed movement. These results have educational and functional implications for children at school and during activities of daily living and leisure activities and for clinicians assessing and treating children with DCD.     

Motor fluency deficits in the sequencing of actions in schizophrenia

Many everyday activities depend on the capacity to organize and smoothly execute motor sequences. The authors tested the hypothesis that a sequencing deficit is associated with schizophrenia. They used a new method to distinguish between lower and higher order mechanisms for the impairment. The 1st task involved triggered sequences in which sensory information from 1 movement was the cue for initiation of the following movement. Results showed that the motor sequences were performed as fluently in patients as in controls. The 2nd and 3rd tasks involved sequences in which the entire movement sequence could be preplanned. Patients executed the sequences less fluently than controls but only under the condition where action sequences were required. Furthermore, the patients' fluency deficit increased with sequence complexity. The high discrimination power of Task 3 gave the authors a means to control for a potential psychometric confound involving differential discriminating power and to argue in favor of a specific higher order motor fluency deficit in patients with schizophrenia. It is suggested that basic lower order mechanisms that integrate sensory information with outgoing motor commands are preserved in schizophrenia, whereas higher order integrative mechanisms that are required for the smooth coordination of motor sequences are impaired.     

Analysis of a national toll free suicide crisis line in South Africa

The first national toll free suicide crisis line for South Africa was launched in October 2003 with the aim of providing a service dedicated to the prevention of suicide in this country. The intervention was motivated by South Africa's suicide rate which had risen higher than the global suicide rate, with the majority of attempted suicides occurring among people younger than 35 years of age (WHO, 2002). Demographic characteristics of callers were identified to evaluate the perceived helpfulness of this crisis line, so as to inform planning and implementation of future suicide prevention programs. Results showed that the majority of callers were female; between the ages of 16 and 18 years; and lived in the provinces of Gauteng, North West, or KwaZulu Natal. Callers were more likely to be from urban than rural areas; were still at school, unemployed, or studying at a tertiary institution; and had not previously attempted suicide. The majority of participants did perceive the crisis line as helpful. The continued collection of demographic data from the crisis line is recommended so that South Africa can create an updated database of areas and sectors of the population that require suicide intervention, and for planning and implementing suicide prevention programs in this country.     

Dash of Faith: A Faith-Based Participatory Research Pilot Study

The Dash of Faith pilot used a community-based participatory research approach to design an experiential dietary intervention based on two African-American churches, one intervention and one comparison. Congregation members identified components that were incorporated into 12 weekly and 4 monthly sessions, with a goal of increasing fruit and vegetable and lowering fat intake. At 2 months, a marginally significant (p = 0.07) increase in fruit and vegetable consumption was observed in the intervention group but was not maintained at study conclusion. We propose that these mixed findings may be attributable, in part, to bias introduced by the participatory nature of the design.