Conflict in the Dyadic Play of 3-Year-Old Children     

Marion O'Brien  Carolyn Roy  Anne Jacobs  Mery Macaluso  Vicki Peyton 《Early education and development》1999,10(3):289-313

Episodes of conflict provide a rich source of information about children's development of interactive skills. In the present study, 184 3-year-old children were observed in dyadic play and the 287 conflicts that occurred during their play were transcribed and coded. In general, children's conflicts arose in the context of ongoing play and were brief, lasting less than 15 seconds. Most disputes concerned toy possession, and almost 80% were ended by the simple withdrawal of one or the other children from the conflict. When children responded with emotional intensity to conflict, their conflicts lasted longer and were more likely to be followed by continued negative interaction. Individual difference data were available for one member of each dyad observed in play. Children rated in infancy as having difficult temperaments were found to be more intense during conflict, to spend more time in conflict, and to score higher on an index of conflict resolution competence, whereas concurrent social behavior was not related to conflict variables. Girls scored higher than boys on competence at conflict resolution, and children with better language skills spent less time in conflict. The more time children spent in nonmaternal child care up to age 3, the less likely they were to initiate conflict.  相似文献   

Residual force enhancement due to active muscle lengthening allows similar reductions in neuromuscular activation during position- and force-control tasks     

Rhiannon Marion  Geoffrey A. Power 《运动与健康科学(英文)》2020,9(6):670-676

BackgroundResidual torque enhancement (rTE) is the increase in torque observed during the isometric steady state following active muscle lengthening when compared with a fixed-end isometric contraction at the same muscle length and level of neuromuscular activation. In the rTE state, owing to an elevated contribution of passive force to total force production, less active force is required, and there is a subsequent reduction in activation. In vivo studies of rTE reporting an activation reduction are often performed using a dynamometer, where participants contract against a rigid restraint, resisting a torque motor. rTE has yet to be investigated during a position task, which involves the displacement of an inertial load with positional control.MethodsA total of 12 participants (6 males, 6 females; age = 22.8 ± 1.1 years, height = 174.7 ± 8.6 cm, mass = 82.1 ± 37.7 kg; mean ± SD) completed torque- and position-matching tasks at 60% maximum voluntary contraction for a fixed-end isometric contraction and an isometric contraction following active lengthening of the ankle dorsiflexors.ResultsThere were no significant differences in activation between torque- and position-matching tasks (p = 0.743), with ∼27% activation reduction following active lengthening for both task types (p < 0.001).ConclusionThese results indicate that rTE is a feature of voluntary, position-controlled contractions. These findings support and extend previous findings of isometric torque-control conditions to position-controlled contractions that represent different tasks of daily living.  相似文献