The emergence of reaching around 3 to 5 months of age corresponds to a special moment in the infant’s life where the gaze directed toward an object is accompanied by an arm extension also directed toward that same object. This moment, when gaze and arm intersect around a common aim, marks a
Daniela Corbetta, Rebecca F. Wiener, Sabrina L. Thurman and Emalie McMahon
Adam J. Nichol, Edward T. Hall, Will Vickery and Philip R. Hayes
, coaching practice and coach education. An Introduction to Critical Realism Critical realism has only recently been applied in the field of sport coaching (e.g., North, 2013a , 2013b , 2017 ), but offers a set of meta-theoretical assumptions (e.g., emergence, ontological depth and causal theory
Karen J. Tropp and Daniel M. Landers
This study quantified the interaction channels used by intercollegiate field hockey teams and compared these to Bavelas' centrality index and the emergence of leadership/interpersonal attraction. Interaction frequencies, defined as passes to teammates, were determined for each playing position for three teams (N = 37) using 4-3-2-1-1, 5-3-2-1, and 4-2-3-1-1 structural systems. Members of four teams for each system (N = 177) then rated each teammate on leadership and attraction. Analyses of variance showed leadership and attraction differences among low, moderate, and high interactors (p < .05), but these differences disappeared when goalies were eliminated from the analysis. Thus, high-interaction frequencies were not indicative of high leadership and attraction ratings. Only “leadership,” “years on the varsity,” and “attraction” were found to discriminate between captain and noncaptains. The results suggest that for highly dynamic tasks functional centrality and task independency are perhaps more important factors than spatial centrality and high interaction.
Wen-Hao Hsu, Daniel Miranda, Diana Young, Kelly Cakert, Mona Qureshi and Eugene Goldfield
We conducted a longitudinal kinematic study of spontaneous arm and leg motions in 4 supine infants at 3, 4½, and 6 months of age. The study addressed two questions: (a) whether there was a longitudinal change in the synchronization of joint rotations at the hips, knees, shoulders, and elbows, indicating that the arms and legs were moving more independently of each other; and (b) whether, during this period, the spatial location of the hands relative to the shoulders was different from that of the feet relative to the hips, indicating that the infants were beginning to use their upper limbs differently than their lower limbs. We found that, in general, the arms and legs were moving more independently of each other by 6 months of age. At the same time, the infants were more likely to hold their hands away from the body in preparation for making contact with an object in the midline, but they brought their feet close to the body to maximize propulsive kicks. Thus, a reorganization of the relative timing of joint rotations appears to be related to the emergence of different arm and leg functions.
Marlene A. Dixon and Per G. Svensson
rapidly changing, with increased reductions in traditional development funding models, resulting in challenging new situations for civil society actors in low- and middle-income countries ( Appe & Pallas, 2018 ). The changing priorities among funders and donors are increasingly stimulating the emergence
Olivier Oullier, Benoît G. Bardy, Thomas A. Stoffregen and Reinoud J. Bootsma
Surfaces shorter in extent than the feet elicit multi-joint coordination that differs from what is elicited by stance on extensive surfaces. This well-known effect arises from the mechanics of the actor-environment interaction. Multi-joint control of stance is also known to be influenced by non-mechanical aspects of a situation, including participants' task or intention. Intentional constraints do not originate in mechanics, and for this reason one might suppose that constraints imposed by mechanics would dominate constraints imposed by intentions, when the two were in conflict. We evaluated this hypothesis by varying participants' supra-postural task during stance on a short surface. While standing on a 10-cm wide beam, participants were exposed to optic flow generated by fore-aft oscillations of a moving room. Participants faced a target attached to the front wall of the moving room and were asked either to look at the target (with no instruction to move) or intentionally to track it with their head (i.e., to keep the target-head distance constant). Within trials, we varied the frequency of room (and target) motion, from 0.15 to 0.75 Hz, in steps of 0.05 Hz. In both conditions, ankle and hip rotations exhibited antiphase coordination, but behavior was not identical across conditions. Coupling between motion of the room and the head was stronger for the tracking task than for the looking task, and the stability of ankle-hip coordination was greater during tracking than during looking. These results indicate that the influence of support surface mechanics did not eliminate the influence of the supra-postural task. Environment-based and task-based constraints interacted in determining the coordination of hips and ankles during stance.