Action-Perception Coupling

Tennis serve has become one of the most critical strokes-if not the most importantparticularly in men's tennis. The preparatory phase constitutes a decisive factor in its execution, directly influencing effectiveness. The primary objective of this study is to compare the two techniques used in the preparation phase of the serve (foot-up and foot-back) among juniors. Methods: This study followed the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA), primarily by consulting the databases Web of Science, PubMed, Scopus, ScienceDirect, Google Scholar, and ITF Coaching and Sport Science Review. The timeframe covered was 2014-2025, using search terms such as: "tennis serve" OR "tennis serve AND juniors" OR "foot-up AND foot-back" OR "stance" OR "tennis serve AND biomechanics" OR "biomechanics" OR "tennis serve AND biomechanics". Findings: Upon applying the exclusion criteria, only twelve papers qualified. These studies suggest that the footback technique is more suitable during initial training stages for juniors, as it provides greater stability and control. In contrast, the foot-up technique is associated with superior performance in advanced athletes due to more efficient body weight transfer and improved segmental coordination. The optimal stance should be selected based on athletes' physical development, motor skills, and experience. Conclusions: Recent research on tennis serve highlights the absence of a standardised methodology, limiting the comparability of the two positioning techniques. There is an imperative need to develop unified protocols, particularly for juniors. Although the foot-up and foot-back techniques provide distinct advantages, scientific evidence supporting them remains insufficient.

Human beings are intensely social animals. Our lives intertwine with other people. Our health, economic prosperity, and well-being profoundly depend on our interactions with others. Social neuroscience seeks to understand how the brain mediates the dynamic relations between cognition and behavior in social contexts. This academic discipline is at the crossroads of biological sciences and social sciences. It relies on integrating knowledge from diverse disciplines and methods, on topics that are classically examined in social psychology, and this across multiple levels of analyses. Overall, social neuroscience aims to provide an overarching paradigm to investigate social behavior, and to determine where we as a species fit within a broader biological context (Cacioppo & Berntson, 1992).

In 1989, Clark and Whitall asked the question "What is motor development". They were referring to the study of motor development as an academic research enterprise and answered their question primarily by describing four relatively distinct time periods characterized by changes in focus, theories or concepts and methodology. Their last period was named the process-oriented period (1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989). In hindsight, it seems clear that their last period could be divided into two separate historical time periods: the information-processing period (1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982) and the dynamical systems period (1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000). In the present paper, we briefly revisit the first three periods defined by Clark and Whitall, and expand and elaborate on the two periods from 1970 to the turn of the century. Each period is delineated by key papers and the major changes in focus, theories or concepts and methodology. Major findings about motor development are also described from some papers as a means of showing the progression of knowledge.

This article discusses the curiously geographic metaphors that shape how we understand embodied growth and change in infancy and early childhood and explores possibilities for developing new metaphors, and iconographies, which better represent how young children's bodies grow and change. To do this, it explores the dominant milestones metaphor, and its iconography of milestone charts. It then considers alternative metaphors, which represent the dominant approaches within contemporary developmental movement science: Esther Thelen's physical landscape metaphor, which represents the dynamic systems approach, and botanical metaphors, which represent a Gibsonian ecological approach. The paper, then, suggests that Tim Ingold's notion of wayfaring may provide a simpler metaphor that retains the dominant motif of developmental journey while emphasizing the adaptation, flexibility, difference and diversity that characterize the more complex physical landscape and botanical metaphors. In doing so, the paper seeks to develop a metaphor that can meaningfully capture the geographic character of embodied growth and change.

This article discusses the curiously geographic metaphors that shape how we understand embodied growth and change in infancy and early childhood and explores possibilities for developing new metaphors, and iconographies, which better represent how young children’s bodies grow and change. To do this, it explores the dominant milestones metaphor, and its iconography of milestone charts. It then considers alternative metaphors, which represent the dominant approaches within contemporary developmental movement science: Esther Thelen’s physical landscape metaphor, which represents the dynamic systems approach, and botanical metaphors, which represent a Gibsonian ecological approach. The paper, then, suggests that Tim Ingold’s notion of wayfaring may provide a simpler metaphor that retains the dominant motif of developmental journey while emphasizing the adaptation, flexibility, difference and diversity that characterize the more complex physical landscape and botanical metaphors. In doin...

We present a model for the autonomous learning of active binocular vision using a recently developed biome-chanical model of the human oculomotor system. The model is formulated in the Active Efficient Coding (AEC) framework, a recent generalization of classic efficient coding theories to active perception. The model simultaneously learns how to efficiently encode binocular images and how to generate accurate vergence eye movements that facilitate efficient encoding of the visual input. In order to resolve the redundancy problem arising from the actuation of the eyes through antagonistic muscle pairs, we consider the metabolic costs associated with eye movements. We show that the model successfully learns to trade off vergence accuracy against the associated metabolic costs, producing high fidelity vergence eye movements obeying Sherrington’s law of reciprocal innervation.

Motor resonance is considered to be an index of the automatic under threshold motor replica of the observed action. Similar actions may be quite different in terms of long-term goals (e.g., grasp to eat vs grasp to throw) and, recently, it has been proposed that the distal goal subtle modulates movements execution, and that observers automatically use these differences in kinematics to discriminate between different intentions. This interpretation is in line with computational approaches proposing that in the agent the generative process causes that intention shapes the kinematics, and in the observer the recognition process causes that the kinematics cues the intention. Given the close entanglement between the two processes, here we investigated whether the mere knowledge of agent's intentions induces in the observer a generative process able to modulate motor resonance. We used transcranial magnetic stimulation to examine motor evoked potentials in the Opponens Pollicis muscle to verify if observer's knowledge of agent's positive, negative, or neutral intentions on a third person influences corticospinal excitability during observation of the same action performed with equal kinematics, and in the same visual context. Results showed that the observation of an action executed with the intention to induce negative effects determined a reduction of motor resonance, revealing the presence of a specific inhibition to reenact an action that results in unpleasant consequences in the other. These data suggest that the information at the intention level activates a generative process which overcomes the replica of kinematics at the goal level, and shapes motor resonance according with observer's mind and not with agent's intention, revealing the possibility of a mere cognitive influence on motor resonance based on individual's ethical values.

Imitation, both gestural and vocal, has been acknowledged to be at the origin of human communication (Donald, 1991). Music is often considered to be the first means of communication of emotion via both vocal and gestural synchronization (Malloch, 1999; Malloch and Trevarthen, 2009). Instrumental music is part of the human heritage for more than 35,000 years before our era (Aimé et al., 2020). However, very little is known about the acquisition of gestures that produce sounds (i.e., musical gestures) and their role in the development of music and musicality. In the present paper, we propose that studying early synchronous imitation of musical gestures is essential both for investigating the development of the early action-perception system and for outlining early music interventions during infancy. We designed double musical objects which can be used in preschool music education for prompting synchronic imitation of musical gestures between adult and child, and between dyads of infants. We conclude by proposing a novel pedagogical perspective in music education for the early years which links the privileged orientation of infants and children towards sound discoveries with the development of perception-action coupling via imitation of musical gestures.

The paper reports an electrophysiological (EEG) study investigating how language is involved in perception–action relations in musically trained and untrained participants. Using an original backward priming paradigm, participants were exposed to muted point-light videos of violinists performing piano or forte nuances followed by a congruent vs. incongruent word. After the video presentation, participants were asked to decide whether the musician was playing a piano or forte musical nuance. EEG results showed a greater P200 event-related potential for trained participants at the occipital site, and a greater N400 effect for untrained participants at the central site. Musically untrained participants were more accurate when the word was semantically congruent with the gesture than when it was incongruent. Overall, language seems to influence the performance of untrained participants, for which perception–action couplings are less automatized.

Background Previous work on balance control in children and adults highlights the importance of multisensory information. Work in this vein has examined two principal input sourcesthe role of visual and haptic information on balance. Recent work has explored the impact of a different form of haptic inputobject holdingon balance in young infants. Research question This experiment examined the impact of simultaneous visual input and haptic input on balance in children and adults, employing two novel forms of haptic input. Methods Static balance was measured in 3-5 year olds, 7-9 year olds, and young adults, in the presence of all possible combinations of manipulated visual input (eyes open, eyes closed) and haptic input (no touch, object hold, touch an unstable support, touch a stable support). Results Analysis of postural stability (mean velocity) indicated that stability was influenced by visual input, haptic input, and age group. For visual input stability increased in eyes open versus eyes closed conditions. For haptic input, stability systematically increased with increasing levels of fixed haptic input (e.g., no touch, object hold, unstable touch, stable touch). Stability also increased as a function of increasing age group. There were no interactions between the factors. Significance The finding that the two novel forms of haptic inputobject hold and touch with an unstable support surfaceincreased stability relative to no touch input, but not as much as touch with a stable support, indicates that children use haptic information in a self-referential fashion for controlling posture. The failure to observe any interactions between visual and haptic inputs with age suggests that multisensory processing is generally additive across development, and has implications for the occurrence of sensory weighting across developmental epochs.

Results The results showed that the APC related to reaching-to-grasp performance was not impacted by postexercise changes in mechanical properties of the musculoarticular system. Conclusion These findings emphasize the central dimension of sensorimotor processing instead of peripheral structures to investigate the APC for an altered sensorimotor environment.

A dynamical systems approach is used to characterize early motor development. Contemporary theories of motor performance emphasize the self-organizing and autonomous properties of muscle synergies as an example of the dynamical behavior of complex, nonlinear systems. The organization of leg movements in infants is consistent with the dynamical approach. Using this perspective, we view skill development as a multidimensional, emergent phenomenon. The developmental principles derived from motor behavior may apply to other domains.

This article examines what might constitute the first manifestation of consciousness in the life of an individual, focusing on the subjective starting state of newborns. It presents evidence showing that we are born with some minimal self-awareness, a kind of aware ness that might even be present in foetuses depending on the criteria used. It investi gates the mechanisms that might account for how self-awareness quickly evolves from be ing minimal and phenomenal in the context of sensation, perception, and action and dis cusses the innate propensity of newborns to detect sameness in the experience of things that surround them. It identifies two putative mechanisms that would support an innate propensity to detect sameness: synesthesia and the vicariousness of experience.

A review and synthesis of the literature on the learning and development of motor skills supports the postulation that whether a motor skill can be deemed fundamental is dependent on the collective presence of three conditions: (i) uniqueness to the movement pattern and/or outcome; (ii) near universality of the functional outcome in the healthy population; (iii) capacity to act as an antecedent influence supporting generalization to a large and broad set of perceptual-motor skills. Within this framework, it is proposed that the infant motor development sequence underpinning upright posture (e.g., sitting, bipedal standing), locomotion (e.g., walking, running), and object-interaction (e.g., grasping) represents the minimum set of fundamental motor skills from which all other skills evolve with over the lifespan. This position is in contrast to the views of many students of motor development and learning who describe numerous skills that typically emerge in the ∼2- to 18-year-old rang...

Empathy with others' successes and misfortunes is a critical component of group living that promotes social cohesion. Unfortunately, empathy is a malleable phenomenon in that its elicitation is not automatic, but modulated by multiple interlocking factors. This chapter explores the specific phenomenon of intergroup empathy bias-the difference in empathy for members of social ingroups versus outgroups-which poses profound challenges for our modern human world characterized by a multitude of groups, ethnicities, and cultures. The chapter frames the discussion by contextualizing empathy as consisting of three interacting component processes, namely experience sharing, perspective taking, and empathic concern. It then goes on to examine research describing the effects of intergroup bias on each of these component processes. Next, it explores the factors, both at the level of the group and at the level of the individual, which may contribute to empathic breakdown in intergroup contexts. Finally, it considers strategies that may have potential in mitigating intergroup empathy bias. Here, we draw on our own experiences in the South African context, which is characterized by pervasive racial inequality and legacies of apartheid violence, to suggest that intergroup empathy is best stimulated in a context of reciprocal mutual engagement with the other.

Contextual information accompanying others’ actions modulates “motor resonance”, i.e., neural activity within motor areas that is elicited by movement observation. One possibility is that we weigh and combine such information in a Bayesian manner according to their relative uncertainty. Therefore, contextual information becomes particularly useful when others’ actions are difficult to discriminate. It is unclear, however, whether this uncertainty modulates the neural activity in primary motor cortex (M1) during movement observation. Here, we applied single-pulse transcranial magnetic stimulation (TMS) while subjects watched different grasping actions. We operationalized motor resonance as grip-specific modulation of corticomotor excitability measured in the index (FDI) versus the little finger abductor (ADM). We experimentally modulated either the availability of kinematic information ( experiment 1) or the reliability of contextual cues ( experiment 2). Our results indicate that ev...

All spatially and temporally coordinated behaviors are organized as action systems involving the coupling of perception and action. Some action systems are present at birth, but most will develop in the months and years to come; all of them will become better coordinated and tuned as a function of both neural development and experience. A number of key principles for explaining how perception and action are coupled are presented with specific examples from infant development, and followed by a discussion of specific change mechanisms responsible for the development of action systems.

In 1989, Clark and Whitall asked the question, “What is motor development?” They were referring to the study of motor development as an academic research enterprise and answered their question primarily by describing four relatively distinct time periods characterized by changes in focus, theories or concepts, and methodology. Their last period was named the process-oriented period (1970–1989). In hindsight, it seems clear that their last period could be divided into two separate historical time periods: the information-processing period (1970–1982) and the dynamical systems period (1982–2000). In the present paper, we briefly revisit the first three periods defined by Clark and Whitall, and expand and elaborate on the two periods from 1970 to the turn of the century. Each period is delineated by key papers and the major changes in focus, theories or concepts, and methodology. Major findings about motor development are also described from some papers as a means of showing the progre...

The goals of this study were to examine the visual information influence on body sway as a function of self-and object-motion perception and visual information quality. Participants that were aware (object-motion) and unaware (self-motion) of the movement of a moving room were asked to stand upright at five different distances from its frontal wall. The visual information effect on body sway decreased when participants were aware about the sensory manipulation. Moreover, while the visual influence on body sway decreased as the distance increased in the selfmotion perception, no effects were observed in the object-motion mode. The overall results indicate that postural control system functioning can be altered by prior knowledge, and adaptation due to changes in sensory quality seem to occur in the self-but not in the object-motion perception mode.

Skilled actions are the result of a perceptual-motor system being well-calibrated to the appropriate information variables. Changes to the perceptual or motor system initiates recalibration, which is the rescaling of the perceptual-motor system to informational variables. For example, a professional baseball player may need to rescale their throws due to fatigue. The aim of this systematic review is to analyse how recalibration can and has been measured and also to evaluate the literature on recalibration. Five databases were systematically screened to identify literature that reported experiments where a disturbance was applied to the perceptual-motor system in functional perceptual-motor tasks. Each of the 91 experiments reported the immediate effects of a disturbance and/or the effects of removing that disturbance after recalibration. The results showed that experiments applied disturbances to either perception or action, and used either direct or indirect measures of recalibrati...

An experiment was conducted to examine whether basketball jump shooting relies on online visual (i.e., dorsal stream-mediated) control rather than motor preprogramming. Seventeen expert basketball players (eight males and nine females) performed jump shots under normal vision and in three conditions in which movement initiation was delayed by zero, one, or two seconds relative to viewing the basket. Shots were evaluated in terms of both outcome and execution measures. Even though most shots still landed near the basket in the absence of vision, end-point accuracy was significantly better under normal visual conditions than under the delay conditions, where players tended to undershoot the basket. In addition, an overall decrease of inter-joint coordination strength and stability was found as a function of visual condition. Although these results do not exclude a role of motor preprogramming, they demonstrate that visual sensory information plays an important role in the continuous guidance of the basketball jump shot.

Empathy with others' successes and misfortunes is a critical component of group living that promotes social cohesion. Unfortunately, empathy is a malleable phenomenon in that its elicitation is not automatic, but modulated by multiple interlocking factors. This chapter explores the specific phenomenon of intergroup empathy bias-the difference in empathy for members of social ingroups versus outgroups-which poses profound challenges for our modern human world characterized by a multitude of groups, ethnicities, and cultures. The chapter frames the discussion by contextualizing empathy as consisting of three interacting component processes, namely experience sharing, perspective taking, and empathic concern. It then goes on to examine research describing the effects of intergroup bias on each of these component processes. Next, it explores the factors, both at the level of the group and at the level of the individual, which may contribute to empathic breakdown in intergroup contexts. Finally, it considers strategies that may have potential in mitigating intergroup empathy bias. Here, we draw on our own experiences in the South African context, which is characterized by pervasive racial inequality and legacies of apartheid violence, to suggest that intergroup empathy is best stimulated in a context of reciprocal mutual engagement with the other.

This study examined twenty two 11-and 13-month-old infants' approach and grasp of two objects-one symmetric and one asymmetric-in an effort to understand infants' use of shape information to plan motor action. At first contact, all infants grasped the asymmetrical object further from its center of mass than the symmetrical object. In addition, results highlighted developmental differences in infants' abilities to correct for less stable hand placements, to maintain control of the objects without dropping, strategies used to obtain the objects, and latencies to grasp the objects. Older infants showed more effective skills in each of the aforementioned areas. Implications for our understanding of the development of processing of visual information for action are discussed.

Introduction Perception of absolute distance is important for everyday navigational goals that rely on the ability to recover the scale of a space such as planning a locomotor path through an environment. Given that we perform tasks based on absolute scale with ease and accuracy over distances of several tens of meters, it is an intriguing problem to consider that there are only a few depth cues that can be used to recover absolute egocentric distances to locations more than 2^3 m away from the observer. Sedgwick (1983) proposed what he called the horizon^distance relation as one mechanism by which a viewer standing on a ground surface might recover absolute egocentric distance to environmental locations also on that ground surface. The horizon^distance relation, often referred to as the angle of declination, suggests that the distance to a point on an infinite ground plane can be computed as a function of eye height and the angle between the line of sight to the horizon and line of sight to the object (see figure 1). In addition to describing the horizon^distance relation itself, Sedgwick raises two questions about how the visual system might utilize it to make distance judgments: (i) Is the visual horizon used to establish a frame of reference from which angle of declination to the target line of sight can be determined, or instead is the frame of reference established using proprioceptive information that relates to gravity-relative vertical? (ii) If the visual horizon is in fact used, what happens with truncated ground planes, for which the visual horizon no longer corresponds to the`true' horizon corresponding to an infinite ground plane? The study reported here provides evidence for the use of the horizon^distance relationship in human vision, and then offers insights about the role of the visual horizon and the effects of a truncated ground plane. The horizon^distance relation builds on Gibson's (1950) ground theory of perception, which asserts that spaces are perceived within the context of support surfaces. While many potential surfaces exist, the most fundamental was suggested to be the terrestrial surface as it extends to the horizon, and the perception of such surfaces The importance of a visual horizon for distance judgments under severely degraded vision

Motor control deficits outlasting self-reported symptoms are often reported following mild traumatic brain injury (mTBI). The exact duration and nature of these deficits remains unknown. The current study aimed to compare postural responses to static or dynamic virtual visual inputs and during standard clinical tests of balance in 38 children between 9 and 18 years-of-age, at 2 weeks, 3 and 12 months post-concussion. Body sway amplitude (BSA) and postural instability (vRMS) were measured in a 3D virtual reality (VR) tunnel (i.e., optic flow) moving in the antero-posterior direction in different conditions. Measures derived from standard clinical balance evaluations (BOT-2, Timed tasks) and post-concussion symptoms (PCSS-R) were also assessed. Results were compared to those of 38 healthy non-injured children following a similar testing schedule and matched according to age, gender, and premorbid level of physical activity. Results highlighted greater postural response with BSA and vR...

A review and synthesis of the literature on the learning and development of motor skills supports the postulation that whether a motor skill can be deemed fundamental is dependent on the collective presence of three conditions: (i) uniqueness to the movement pattern and/or outcome; (ii) near universality of the functional outcome in the healthy population; (iii) capacity to act as an antecedent influence supporting generalization to a large and broad set of perceptual-motor skills. Within this framework, it is proposed that the infant motor development sequence underpinning upright posture (e.g., sitting, bipedal standing), locomotion (e.g., walking, running), and object-interaction (e.g., grasping) represents the minimum set of fundamental motor skills from which all other skills evolve with over the lifespan. This position is in contrast to the views of many students of motor development and learning who describe numerous skills that typically emerge in the ∼2- to 18-year-old rang...

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Several studies have emphasized the contribution of haptic input that results from the use of rigid and non-rigid tools to the postural control system. Experimental protocols such as the light touch and the anchor system are based on individuals' haptic exploration of the environment through direct tactile-kinesthetic contact, or indirectly through rigid or flexible tools that are attached to the body. In this article, we introduce the main findings of humans' haptic use of non-rigid tools during postural control tasks. We illustrate the effects of an anchor system paradigm on the maintenance of stability via haptic information. Haptic anchoring includes the handling of flexible cables that are attached to loads that are in contact with a surface. We include results of studies about haptic information gathered during the holding of a walking dog's leash. Studies that used the anchor system demonstrated its effectiveness in reducing body sway in several groups, including young adults, children, older individuals, and intellectually disabled individuals. We discuss several experimental designs and intervention protocols in order to illustrate how haptic anchoring could prompt functional plasticity.

The motor system is engaged when we perceive movement in the environment, even when we have no sensorimotor experience of that movement. It has been suggested that this ability relies on internal models that comprise specific exteroceptive representations, such as audition and vision. It has been shown that, for human movements, the quality of perception depends on the closeness between the perceived movement and the perceiver's own capability of reproducing it. Thus, if we are able to reproduce a movement, we also have the interoceptive motor memories that enable us to run internal models and perceive the same movements more accurately when merely observed. In a behavioral study we investigated if participants would be able to distinguish between self-produced and other-produced movement sounds from a previously recorded hurdling performance. We also analyzed if participants' discriminative ability would vary as a function of specific sound features, examining rhythmic step...

The experiment examined the role of head stabilization in reaching tasks carried out by 6-8 month old infants. The rational for this experiment is found in the findings reported by Fontaine a & Pierautle Bonn& (1988). These researchers showed that in 4 to 9 month old infants the level of postural control is a better predictor of reaching capabilities than age. The importance of the postural system in relation to motor action is emphasized by Reed (1989): 'the postural system is that group of diverse processes-perceptual as well as motor-which serves to maintain body orientation to the environment and its features'. One of the results of an increasing postural control is the ability to stabilize head orientation. the latter is an important factor in motor action (Berholz, 1992). In order to investigate whether the control of head stability is responsible for improved reaching and grasping during infancy, head orientation was manipulated. More specifically, the question was: Does a perturbation of the orientation of the head (and eyes) affect reaching and grasping? Infants were required to reach and grasp for a small or large ball, while during half of the trials head orientation was disturbed by using a moving room, and on half of the trials not (stationary condition). By using video and kinematic 3-D analyses the quality and quantity of the coordination pattern was analysed. The results showed differences between the stationary and moving room condition in the frequency of reaches and in the time between are maximum velocity and grasp of the ball. These findings are discussed in the context of the coupling of perception and action, especially with respect to head orientation (perception) and hand coordination (motor).

The objective of this study was to investigate the effect of additional weight load on reaching movement characteristics in 4-6-month-old infants over age. The task-load provided adaptedness on infant reaching movements, especially influencing to optimal interlimb coupling in bimanual reaches.

In this tribute to Esther Thelen's legacy, it is discussed how she brought concepts of new theoretical perspectives into the domain of motor development. As a consequence of this a rejuvenalisation of motor development took place in the mid 1980's. The study of motor development skills became a testing ground not only for the task at hand, but also for other areas of development.

In this paper the role of exploration in the development of action is discussed from the perspective of the natural physical approach. It is argued that by means of repeated exploration of the perceptual-motor work space, infants discover new couplings between ...

The fingerings used by keyboard players are determined by a range of ergonomic (anatomic/motor), cognitive, and music-interpretive constraints. We have attempted to encapsulate the most important ergonomic constraints in a model. The model, which is presently limited to isolated melodic fragments, begins by generating all possible fingerings, limited only by maximum practical spans between finger pairs. Many of the fingerings generated in this way seldom occur in piano performance. In the next stage of the model, the difficulty of each fingering is estimated according to a system of rules. Each rule represents a specific ergonomic source of difficulty. The model was subjected to a preliminary test by comparing its output with fingerings written by pianists on the scores of a selection of short Czerny studies. Most fingerings recommended by pianists were among those fingerings predicted by the model to be least difficult; but the model also predicted numerous fingerings that were not...

Motor control deficits outlasting self-reported symptoms are often reported following mild traumatic brain injury (mTBI). The exact duration and nature of these deficits remains unknown. The current study aimed to compare postural responses to static or dynamic virtual visual inputs and during standard clinical tests of balance in 38 children between 9 and 18 years-of-age, at 2 weeks, 3 and 12 months post-concussion. Body sway amplitude (BSA) and postural instability (vRMS) were measured in a 3D virtual reality (VR) tunnel (i.e., optic flow) moving in the antero-posterior direction in different conditions. Measures derived from standard clinical balance evaluations (BOT-2, Timed tasks) and post-concussion symptoms (PCSS-R) were also assessed. Results were compared to those of 38 healthy non-injured children following a similar testing schedule and matched according to age, gender, and premorbid level of physical activity. Results highlighted greater postural response with BSA and vR...

This study investigated split-step timing when returning serves and whether this timing is related to neuromechanical capabilities in world-class tennis players. In Experiment 1, the split-step timing of four groups of world-class players (male and female ATP/WTA seniors, and ITF juniors) was measured on court when returning serves of the same level players. The four groups initiated the split-step at a similar time, starting around the time ball-racket contact in the serve stroke and landed when early ball-flight information was available. In Experiment 2, the neuromechanical capabilities (leg stiffness and vertical jump performance) of a group of world-class players and three groups of less-skilled tennis players were examined. The results showed an increase in leg stiffness with an increase in level of expertise. A crossexperiment analysis in world-class male players (ATP/ITF, n = 10) revealed that the timing of initial foot movement was significantly correlated with the leg stiffness (r 2 =0.54), with later lateral step after the serve in the players who had higher stiffness. The findings support the hypothesis that world-class tennis players adapt perceptual-motor control on the basis of their neuromechanical capabilities and maximise the time before initiating their interceptive action to rely on more reliable information.