Uncontrolled manifold analysis of joint angle variability during table tennis forehand

This study was conducted with the objective of evaluating the variance structure of the trunk and racket arm joint angles in table tennis topspin forehand using the uncontrolled manifold (UCM) approach, regarding racket orientation as the task variable. Nine advanced and eight intermediate male collegiate table tennis players performed the topspin strokes against backspin balls. The trunk, upper limb, and racket were modeled as six rigid-link segments with a total of 16 rotation degrees of freedom. The UCM analysis was conducted using 30 trial datasets per participant to quantify the degree of redundancy exploitation needed to stabilize the vertical and horizontal angles of the racket. Irrespective of the performance level, the variance of the joint angle vector increased towards ball impact. The degree of redundancy exploitation increased towards ball impact. As a result, the variability of the racket angles was minimal at impact. Both groups of players used the relative movement between the racket and the hand to stabilize the racket angles at ball impact. The variance of the joint angle vector that affected the vertical racket face angle at ball impact was significantly smaller for advanced players than for intermediate players, and the degree of redundancy exploitation to stabilize that angle at impact tended to be larger for the advanced players. The ability to use the redundancy of the joint configuration to stabilize the vertical racket face angle at impact may be a critical factor that affects performance level.     

The comprehension of action-related sentences may cause interference rather than facilitation on matching actions

This study used a dual-task paradigm to analyze the time course of motor resonance during the comprehension of action language. In the study, participants read sentences describing a transfer either away from (“I threw the tennis ball to my rival”) or toward themselves (“My rival threw me the tennis ball”). When the transfer verb appeared on the screen, and after a variable stimulus onset asynchrony (SOA), a visual motion cue (Experiment 1) or a static cue (Experiment 2) prompted participants to move their hand either away from or toward themselves to press a button. The results showed meaning–action interference at short SOAs and facilitation at the longest SOA for the matching conditions. These results support the hypothesis that motor processes associated with the comprehension of action-related language interfere with an overlapping motor task, whereas they facilitate a delayed motor task. These effects are discussed in terms of resonance processes in the motor cortex.     

Bouncing a ball: tuning into dynamic stability

Rhythmically bouncing a ball with a racket was investigated and modeled with a nonlinear map. Model analyses provided a variable defining a dynamically stable solution that obviates computationally expensive corrections. Three experiments evaluated whether dynamic stability is optimized and what perceptual support is necessary for stable behavior. Two hypotheses were tested: (a) Performance is stable if racket acceleration is negative at impact, and (b) variability is lowest at an impact acceleration between -4 and -1 m/s2. In Experiment 1 participants performed the task, eyes open or closed, bouncing a ball confined to a 1-dimensional trajectory. Experiment 2 eliminated constraints on racket and ball trajectory. Experiment 3 excluded visual or haptic information. Movements were performed with negative racket accelerations in the range of highest stability. Performance with eyes closed was more variable, leaving acceleration unaffected. With haptic information, performance was more stable than with visual information alone.     

Stimulus expectancy modulates inferior frontal gyrus and premotor cortex activity in auditory perception

In studies on auditory speech perception, participants are often asked to perform active tasks, e.g. decide whether the perceived sound is a speech sound or not. However, information about the stimulus, inherent in such tasks, may induce expectations that cause altered activations not only in the auditory cortex, but also in frontal areas such as inferior frontal gyrus (IFG) and motor cortices, even in the absence of an explicit task. To investigate this, we applied spectral mixes of a flute sound and either vowels or specific music instrument sounds (e.g. trumpet) in an fMRI study, in combination with three different instructions. The instructions either revealed no information about stimulus features, or explicit information about either the music instrument or the vowel features. The results demonstrated that, besides an involvement of posterior temporal areas, stimulus expectancy modulated in particular a network comprising IFG and premotor cortices during this passive listening task.     

The effect of local kinematic changes on anticipation judgments

Skilled tennis players rely on a more global than local perceptual strategy when anticipating an opponent’s shot direction in tennis (Williams, Huys, Cañal-Bruland, & Hagemann, 2009). Global perceptual strategy refers to the pick-up of dynamic information across different body areas rather than from a single source such as the arm or racket. We extend previous work by examining the spatiotemporal characteristics of visual information pick-up when anticipating shot direction in tennis. We perturbed information from various body locations by interchanging the dynamics of selected areas with those from strokes played to the opposite side of the court. In addition, we presented each manipulation under four different temporal occlusion conditions (from 240 ms prior to racket-ball contact) to examine the time course of information extraction. Skilled tennis players outperformed less skilled counterparts in predicting shot direction, even at early phases of the opponent’s motion. Moreover, skilled players showed significant decrements in performance when the arms and racket were perturbed, highlighting the relevance of distal information when anticipating opponents’ intentions.     

The use of anticipatory visual cues by highly skilled tennis players

The authors examined 13 skilled and 12 novice tennis performers' ability to use visual information of an opponent's movement pattern to anticipate and respond. In Experiment 1, skilled and novice players anticipated the type of stroke and the direction in which the ball was hit in a highly coupled perception-action environment. Both groups of players correctly anticipated at greater than chance levels. Skilled players were significantly more accurate than novices with live and video displays but not with point-light displays. In Experiment 2, the reaction latencies of 10 expert performers were significantly faster when they returned balls hit by a live opponent than when they returned balls projected from a cloaked ball machine. The findings indicate that experts are able to use movement-pattern information to determine shot selection and to use that information to significantly reduce their response delay times. The findings are discussed in terms of perception-action coupling in time-stress activities.     

Did you see that? Dissociating advanced visual information and ball flight constrains perception and action processes during one-handed catching

The integration of separate, yet complimentary, cortical pathways appears to play a role in visual perception and action when intercepting objects. The ventral system is responsible for object recognition and identification, while the dorsal system facilitates continuous regulation of action. This dual-system model implies that empirically manipulating different visual information sources during performance of an interceptive action might lead to the emergence of distinct gaze and movement pattern profiles. To test this idea, we recorded hand kinematics and eye movements of participants as they attempted to catch balls projected from a novel apparatus that synchronised or de-synchronised accompanying video images of a throwing action and ball trajectory. Results revealed that ball catching performance was less successful when patterns of hand movements and gaze behaviours were constrained by the absence of advanced perceptual information from the thrower's actions. Under these task constraints, participants began tracking the ball later, followed less of its trajectory, and adapted their actions by initiating movements later and moving the hand faster. There were no performance differences when the throwing action image and ball speed were synchronised or de-synchronised since hand movements were closely linked to information from ball trajectory. Results are interpreted relative to the two-visual system hypothesis, demonstrating that accurate interception requires integration of advanced visual information from kinematics of the throwing action and from ball flight trajectory.     

Importance of head movements in gaze tracking during table tennis forehand stroke

The purpose of this study was to clarify the properties of gaze and head movements during forehand stroke in table tennis. Collegiate table tennis players (n = 12) conducted forehand strokes toward a ball launched by a skilled experimenter. A total of ten trials were conducted for the experimental task. Horizontal and vertical movements of the ball, gaze, head and eye were analyzed from the image recorded by an eye tracking device. The results showed that participants did not always keep their gaze and head position on the ball throughout the entire ball path. Our results indicate that table tennis players tend to gaze at the ball in the initial ball-tracking phase. Furthermore, there was a significant negative correlation between eye and head position especially in the vertical direction. This result suggests that horizontal VOR is suppressed more than vertical VOR in ball-tracking during table tennis forehand stroke. Finally, multiple regression analysis showed that the effect of head position to gaze position was significantly higher than that of eye position. This result indicates that gaze position during forehand stroke could be associated with head position rather than eye position. Taken together, head movements may play an important role in maintaining the ball in a constant egocentric direction in table tennis forehand stroke.     

Peak velocity as a cue in audiovisual synchrony perception of rhythmic stimuli

This study investigated audiovisual synchrony perception in a rhythmic context, where the sound was not consequent upon the observed movement. Participants judged synchrony between a bouncing point-light figure and an auditory rhythm in two experiments. Two questions were of interest: (1) whether the reference in the visual movement, with which the auditory beat should coincide, relies on a position or a velocity cue; (2) whether the figure form and motion profile affect synchrony perception. Experiment 1 required synchrony judgment with regard to the same (lowest) position of the movement in four visual conditions: two figure forms (human or non-human) combined with two motion profiles (human or ball trajectory). Whereas figure form did not affect synchrony perception, the point of subjective simultaneity differed between the two motions, suggesting that participants adopted the peak velocity in each downward trajectory as their visual reference. Experiment 2 further demonstrated that, when judgment was required with regard to the highest position, the maximal synchrony response was considerably low for ball motion, which lacked a peak velocity in the upward trajectory. The finding of peak velocity as a cue parallels results of visuomotor synchronization tasks employing biological stimuli, suggesting that synchrony judgment with rhythmic motions relies on the perceived visual beat.     

Differential reactions of virtual actors and observers to the triggering and interruption of psychological momentum

The present study compared virtual actors’ and observers’ perceptions of positive and negative psychological momentum (PM) and their responses to sudden interruptions of momentum. Participants with experience playing competitive table tennis imagined that they were playing a table tennis game (virtual actors), whereas participants who lacked experience playing competitive table tennis imagined that they were observing a table tennis game (observers). While viewing an audiovisual simulation of a table tennis match, participants were exposed to either an ascending (i.e., positive momentum) or descending (i.e., negative momentum) scoring sequence that was either suddenly interrupted or not interrupted at all. Participants’ PM perceptions were measured at the conclusion of the simulation. Results indicated that observers’ PM perceptions were lower than were virtual actors’ following the negative momentum sequence. More generally, interrupting positive momentum lowered PM perceptions, whereas interrupting negative momentum increased PM perceptions. Implications for the study of PM in sport are discussed.     

On-court position and handedness in visual anticipation of stroke direction in tennis

ObjectivesIn racket sports, players integrate information picked up from their opponent's kinematics and contextual cues like on-court position into shot outcome anticipation. In view of suggested difficulties with anticipating left-handed opponents' action intentions, here we examined whether an opponent's handedness interacts with position-dependency in visual anticipation.Design and methodFollowing a 2 (Group) x 2 (Handedness) x 2 (Position) x 3 (Temporal Occlusion) factorial design, 20 tennis players and 20 non-players predicted directional outcome of temporally manipulated point-light animations of identical left- and right-handed forehand groundstrokes performed near vs. far from the court's midline.ResultsTennis players' response selection was mostly affected by an opponent's on-court position, particularly at an early stage of a hitting movement. Opponents' handedness affected response selection similarly in both groups (i.e., bias towards down-the-line predictions against left-handed strokes occluded at racket-ball-contact), but it did not interact with on-court position.ConclusionsFindings highlight that on-court position, and opponents' handedness to some extent as well, appears relevant for skilled visual anticipation in tennis.     

Implicit motor learning and complex decision making in time-constrained environments

The cost-effectiveness of the implicit (procedural) knowledge that supports motor expertise enables surprisingly efficient performance when a decision and an action must occur in close temporal proximity. The authors argue that if novices learn the motor component of performance implicitly rather than explicitly, then they will also be efficient when they make a decision and execute an action in close temporal proximity. Participants (N = 35) learned a table tennis shot implicitly or explicitly. The authors assessed participants' motor performance and movement kinematics under conditions that required a concurrent low-complexity decision or a concurrent high-complexity decision about where to direct each shot. Performance was disrupted only for participants who learned explicitly when they made high-complexity decisions but not when they made low-complexity decisions. The authors conclude that implicit motor learning encourages cognitively efficient motor control more than does explicit motor learning, which allows performance to remain stable when time constraints call for a complex decision in tandem with a motor action.     

Field dependence-independence in complex motor skills

This study analyzed the relationship between field dependence-independence and complex motor skills. According to the requirements of each sporting activity, subjects' motor system can be mainly controlled through exteroceptive or proprioceptive information. Sport performances require the athlete to disembed himself, other players, or the ball from the background, and decision-making appears to require cognitive restructuring. 26 athletes (13 men and 13 women) involved in acrobatic sports (gymnastics, trampoline, half-pipe snowboard, synchronized 3-m springboard, acrobatic rock, skateboard, and free skating) and 26 athletes (13 men and 13 women) involved in individual racket sports (tennis and table-tennis) completed the Group Embedded Figures Test. Participants (at least 10 years of practice) were from 16 to 35 years of age (M=22.0, SD=3.1). No significant difference among athletes on scores for field dependence-independence was evidenced given this expertise, sex, or age. Significantly higher scores were obtained by athletes in acrobatic sports, indicating that they tended to be predominately more field-independent whereas the lower scores were obtained by tennis and table-tennis players.     

Auditory cueing facilitates temporospatial accuracy of sequential movements

Effectively executing goal-directed behaviours requires both temporal and spatial accuracy. Previous work has shown that providing auditory cues enhances the timing of upper-limb movements. Interestingly, alternate work has shown beneficial effects of multisensory cueing (i.e., combined audiovisual) on temporospatial motor control. As a result, it is not clear whether adding visual to auditory cues can enhance the temporospatial control of sequential upper-limb movements specifically. The present study utilized a sequential pointing task to investigate the effects of auditory, visual, and audiovisual cueing on temporospatial errors. Eighteen participants performed pointing movements to five targets representing short, intermediate, and large movement amplitudes. Five isochronous auditory, visual, or audiovisual priming cues were provided to specify an equal movement duration for all amplitudes prior to movement onset. Movement time errors were then computed as the difference between actual and predicted movement times specified by the sensory cues, yielding delta movement time errors (ΔMTE). It was hypothesized that auditory-based (i.e., auditory and audiovisual) cueing would yield lower movement time errors compared to visual cueing. The results showed that providing auditory relative to visual priming cues alone reduced ΔMTE particularly for intermediate amplitude movements. The results further highlighted the beneficial impact of unimodal auditory cueing for improving visuomotor control in the absence of significant effects for the multisensory audiovisual condition.     

Response selection and execution skills of professionals and novices during singles tennis competition.

This study extended research on sport expertise concerning the development of cognitive and motor skills in singles tennis (McPherson, 1999). 12 adult male professional and novice tennis players were videotaped during singles competition. Opponents for matches were randomly selected within each group of participants. Two tennis experts utilized an observational scale to judge players' performance generated during competition for serves and shots following the serve, e.g.. return of serves, lobs. Each player was scored on three performance components: quality of movement to or control of the ball for serves or shots attempted (control skills), appropriateness of serve or shot selections in the context of game situations (response selection skills), and quality of serves or shots produced (response execution skills). Relative frequency scores for the highest category of each performance component were derived according to the number of opportunities to respond. Serve performance indicated both groups were able to control their serves: however, professionals made more tactical selections and forceful executions. Shot performance indicated professionals made more successful movement to and control of shots, tactical shot selections, and forcing shot executions than novices. Overall, players' tactical response selections were greater than their forceful response executions. Thus, assessing players' decisions during competition may provide vital information concerning tactical skill development. Further, professional players exhibited higher and more consistent tactical behavior than elite collegiate players examined in 1999 by McPherson. Findings were attributed to tactical knowledge and motor skill development resulting from competition and practice experiences.     

认知判断中手部动作模拟的fMRI研究

该研究采用功能磁共振成像技术,考察不同条件下进行工具认知判断时手部姿势对认知判断的影响及动作模拟的神经机制。实验发现：手部姿势存在显著的主效应,冲突手部姿势条件下反应时最慢,且冲突手部姿势条件下与不冲突手部姿势条件下、自然状态条件下反应时存在显著差异,自然状态条件与不冲突手部姿势条件下反应时不存在显著差异。另外,f MRI成像结果发现,额中回、额下回、顶下小叶以及辅助运动区在自然状态下有显著激活,表明个体在进行认知判断过程中有动作模拟过程;海马结构、扣带回及楔前叶等与记忆有关的脑区有显著激活,表明身体经验在认知过程的作用。总的研究表明,不同的手部姿势状态对认知判断有不同影响,冲突手部姿势会对动作模拟产生干扰作用,手部动作模拟的神经机制主要涉及镜像神经元区,且在认知判断时存在具身效应。     

Anticipatory responses to perturbation of co-ordination in one-handed catching.

Anticipatory responses to perturbation have rarely been studied in the co-ordination of dynamic interceptive actions. In this study, the kinematics of ball catching were examined in skilled catchers when mechanical perturbation of the catching arm was expected and unexpected. During trials where the perturbation was anticipated, participants initiated movements earlier (207 +/- 32 ms) than in randomly perturbed trials (223 +/- 34 ms). Furthermore, several individuals also tended to move their hand faster when perturbations were expected compared to baseline trials. Individual analyses revealed that three out of eight participants exhibited changes in the relative timing of the grasp phase to adapt to the specific manipulation of task constraints. Anticipatory responses were revealed in changes not only at movement initiation but also in the resulting adaptations to the co-ordination of reach and grasp phases of ball catching. When the catchers could not anticipate perturbations, movement strategies suggested the use of a continuous tracking-based mode of control rather than a prediction-based mode of control.     

THE CONTRIBUTION OF KINESIC ILLUSTRATORS TOWARD THE COMPREHENSION OF VERBAL BEHAVIOR WITHIN UTTERANCES

The study assessed the extent to which a speaker's visible body movements can improve verbal comprehension for listeners. Subjects responded to multiple-choice items designed to test their comprehension of 12 videotaped spoken utterances which had been obtained by asking speakers to describe either objects in motion (e.g., a tennis ball, a car, spraying water) or abstract concepts. The 60 subjects each responded to stimuli in one of three presentation conditions (audiovisual, audiovisual without lip and facial cues, and audio-alone) over four signal-to-noise ratios. The results indicated that: (1) visual cues can at times significantly improve comprehension scores, even with lip and facial cues not present; (2) visual cues are increasingly useful as noise is introduced; (3) visual cues assist the comprehension of certain grammatical types of verbal segments regardless of semantic content expressed in those type segments.     

Multimodal action representation in human left ventral premotor cortex

We used functional magnetic resonance imaging (fMRI) to investigate the neural systems responding to the sight and to the sound of an action. Subjects saw a video of paper tearing in silence (V), heard the sound of paper tearing (A), and saw and heard the action simultaneously (A + V). Compared to a non-action control stimulus, we found that hearing action sounds (A) activated the anterior inferior frontal gyrus and middle frontal gyrus in addition to primary auditory cortex. The anterior inferior frontal gyrus, which is known to be activated by environmental sounds, also seems to be involved in recognizing actions by sound. Consistent with previous research, seeing an action video (V) compared with seeing a non-action video activated the premotor cortex, intraparietal cortex, and the pars opercularis of the inferior frontal gyrus. An A + V facilitation effect was found in the ventral premotor cortex on the border of areas 44, 6, 3a, and 3b for the action stimuli but not for the control stimuli. This region may be involved in integrating multimodal information about actions. These data provide evidence that the ventral premotor cortex may provide an action representation that abstracts across both agency (self and other) and sensory modality (hearing and seeing). This function may be an important precursor of language functions.