Index for Volume 23

In this study, changes in movement coordination caused by fatigue that developed during repetitive lifting were examined. Five men performed 6 times a 5-min bout of lifting an 8-kg barbell at 15 lifts/min, using two lifting techniques; one minimized trunk rotation (squat lift), and the other minimized rotation in the knee joint (stoop lift). Kinematics and dynamics were studied by means of movement analysis and inverse dynamics, using a two-dimensional linked segment model. Within-subject variation over repetitive lifts of the time course of joint angles was smaller than between-subjects variation on the first analyzed lift. Relative timing between joint rotations did not change significantly across repetitive lifts, except between knee and hip in the squat lift. No change of the lumbosacral torque over repetitive lifts was found. The adaptability of the neural control appeared to be sufficient to accommodate the strong changes of the input-output characteristics of the muscles caused by fatigue so that an essentially constant performance of the movement act was maintained.     

Postural Mechanisms to Control Body Displacements in the Performance of Lateral Gaze Shifts

Medialateral postural control mechanisms (bodyweight distribution and center of pressure location) have been studied in static conditions. Our objective was to determine how these mechanisms are adjusted to perform voluntary movements, in our case 80° lateral gaze shifts at 0.125 Hz and 0.25 Hz. In healthy, young adults, we expected body marker (neck, lower back) and center of pressure displacements to be significantly greater in gaze shift conditions than in the stationary gaze condition. To explain these changes in center of pressure displacement, the amplitude contribution of both mechanisms was expected to increase significantly. All these results were found accordingly. Unexpectedly, the active contribution of the bodyweight distribution mechanism was negatively related to body marker displacements in the gaze shift conditions (ns in stationary condition). Moreover, changes in the contribution of the mechanisms were statistically weaker in effect size than changes in body displacement. However, the participants were not unstable because they performed the visual tasks as requested. We propose that the strength of medialateral postural control mechanisms may not only be strengthened to control challenging ML stance conditions but also slightly weakened to allow the performance of adequate body motions in ongoing tasks.     

The Effects of Eight-Month Physical Activity Intervention on Vigilance Performance in Adult Obese Population

We aim to analyze the effects of an 8-month physical activity intervention on cardiorespiratory fitness, body mass index (BMI), and vigilance performance in an adult obese population. We conducted an 8-month physical activity intervention based on dance and rhythmic activities. The weekly frequency was 2 sessions of 1 hr per day. Training sessions were divided into 3 phases: a 10-min warm-up, 40 min of dance and rhythmic activities, and 10 min to cool-down. To assess cardiorespiratory fitness, participants performed a modified version of the 6-min walk test from the Senior Fitness Test battery (Larsson & Mattsson, 2001; Rikli & Jones, 1999). Vigilance performance was measured by means of the psychomotor vigilance task (PVT). Two measurements were performed immediately before and after the intervention. The results revealed that participants improved their cardiorespiratory fitness, BMI, and vigilance performance after the intervention. All in all, findings contribute new empirical evidence to the field that investigates the benefits of physical activity intervention on cognitive processes in obese population.     

Effect of Short-Term Training on Reaching Behavior in Infants: A Randomized Controlled Clinical Trial

The purpose of this study was to test the effect of short-term training on reaching behavior in infants at the onset of reaching. The study was a single-blind, parallel group design, randomized controlled clinical trial. Thirty healthy infants were randomly assigned to a social control group (n = 15) or a reaching training group (n = 15). Infants began the study up to 3 days after the onset of reaching and were assessed three times across 2 days: pretraining (before training), posttraining 1 (after 1 session of training), and posttraining 2 (after 3 sessions of training). The reaching training group received 3 sessions of training by a physical therapist while the control group received a similar amount of time sitting in the therapist's lap. The data were analyzed using repeated-measures analyses of variance, and independent-samples tests with Bonferroni adjustments. Short-term training resulted in increased frequency of object contacts, shorter and smoother reaches, and improved hand positioning. The few short training sessions likely provided opportunities for infants to explore and learn to select movements from their existing movement repertoire. These results demonstrate that adaptive changes in infants' novel behaviors can emerge rapidly, and highlight the need for increased understanding of how to most effectively time early interventions.     

Psychometric Properties and Clinical Cut-Off Scores of the Spanish Version of the Social Anxiety Scale for Adolescents

Psychotic (P) and Non-Psychotic (N-P) retardates were compared on 13 Rorschach “indicators” of psychosis using a matched pairs technique. Two of the 13 signs were found to significantly differentiate between groups with the P group demonstrating a lower F% and higher C' responding than the N-P group.     

Acculturation,Adaptation and Saudade Among Portuguese Migrants

Saudade is a psychological reaction to the absence of significant others and familiar places. This investigation examined differences in saudade in a sample of 227 Portuguese adults without migratory experience, and 202 Portuguese migrants living in Switzerland. Within the migrant group, the relation between saudade and acculturation and adaptation factors was also examined. Results indicate that migrants experienced higher levels of saudade than did non-migrants. Length of residence abroad influenced the level of saudade: the longer the time spent abroad the less saudade was felt. Acculturation and adaptation factors accounted for 44% of the explained variance in saudade. Among acculturation factors, higher Portuguese proficiency and separation, and lower assimilation predicted more saudade. Among the adaptation factors, higher sociocultural adaptation problems and lower migration satisfaction also predicted higher saudade. It is hoped that investigation on saudade continues, and suggestions are made for further research.     

“We will work for you” – Social influence may suppress individual food preferences in a communicative situation in dogs

The level of motivation (i.e. incentive power) is thought to be one of the most important factors affecting performance and learning in various tasks. We investigated whether reward quality has an effect on the performance of family dogs in a two-way object choice test in which they can find the hidden food by relying on distal momentary human pointing cues. In three experiments we varied (1) the type of food reward according to the subjects’ own preference; (2) the quality of the reward offered at the same time in the indicated and not-indicated locations; and (3) the order of the high or low quality rewards in consecutive sessions. In Experiment 1, we first tested whether dogs prefer one kind of reward over another. Then one group was tested with the ‘preferred’ food as reward in the indicated bowl, while dogs in the other group received the ‘non-preferred’ food as reward. We did not find any difference between the performance and choice latencies of the two groups. In Experiment 2 for the first group, the indicated bowl contained a piece of carrot and the not-indicated bowl was empty. In the second group the indicated bowl contained carrot, but the not-indicated bowl contained sausage. According to a preliminary preference test, most dogs prefer sausage over carrot invariably. After 20 trials, the two groups performed surprisingly similarly. There was no difference found between groups in the number of correct choices, incorrect choices and non-choices. However, the comparison between the first and last five trials revealed that subjects who found sausage when they chose the not-indicated bowl (did not follow the pointing) chose the non-indicated bowl significantly more often toward the end of their test session. In Experiment 3, each dog received two sessions with 12 pointing trials in each. For the first session, one group was rewarded with sausage and the other with carrot upon choosing the indicated bowl. In the second session, the indicated bowl contained dry dog food for both groups. We found that correct choices and response latencies did not change over two sessions in the ‘sausage’ group. In the ‘carrot’ group, the dogs chose faster in the second session, but their performance did not improve; in fact, they chose the not-indicated bowl more often than the indicated bowl. As a conclusion, we can say that reward quality had some effect on dogs’ choice behavior in these experiments. The drop in their performance was not drastic, taking into account the general refusal to eat one of the ‘rewards’ (carrot) during the preference tests and also during the test trials. It seems that incentive contrast may play a relatively minor role in dog-human social interactions. Appropriate reward quality can be very important in asocial problem solving tasks, but, when interacting with humans, following human signals may override the effect of changed incentive power.     

Occupational Choices for People with Psychiatric Disabilities: Comparing Attendees and Non-Attendees at Community-Based Day Centers

Research has shown that people with psychiatric disabilities who attend a day center rate their satisfaction with daily occupations equally in comparison with non-attendees. The current study investigates which occupations the target group performs and also differences in occupational choices between attendees and non-attendees. Reported occupations were analyzed with content analysis. Day center attendees reported more productive occupations, while non-attendees reported more recreational occupations and a greater breadth of occupations. This implies that non-attendees might compensate a lack of work-like occupations at a day center with satisfying recreational occupations. The results can guide development of psychiatric occupational-based rehabilitation.     

Specifying General Strain Theory: An Ethnically Relevant Approach

The current study incorporated principles from the acculturation literature to specify an ethnically relevant general strain theory (GST). This study argues that the acculturation process exposes Hispanics to unique types of strain (e.g., prejudice and discrimination) that may increase the likelihood of delinquency. Further varying levels of Hispanic concentration can moderate the effect of acculturative strain on delinquency, whereby the effect of ethnic-specific strains may be more pronounced where ethnic concentration is low. Responses from self-administered questionnaires of 1,729 Hispanic adolescents were analyzed to test various hypotheses regarding the effects of traditional and acculturation-related strains on violent delinquency. The findings indicated that GST is generalizable to Hispanic adolescents. The analyses also found support for the prediction that, conditional on the level of Hispanic concentration, ethnic-specific strain measures increased the likelihood of violent delinquency among Hispanic adolescents. This study provided a foundation for future empirical analyses of criminological theories among Hispanic populations.