Perception-action coupling and expertise in interceptive actions

The goal of this experiment was to show that expertise in interceptive actions can be explained by a shorter delay in movement regulation. In this contribution, we tested tennis experts and non-experts using a simulated interceptive task. The experimental device simulated linear motion of an object toward a target on a horizontal runway. Participants had to intercept the simulated moving object with their right hand holding a cart that could slide along a horizontal track perpendicular to the runway. Three different velocity conditions were used: a constant velocity condition that maintained the initial velocity (2m/s) constant until arriving on the target; the decelerated and accelerated velocity conditions, in which the velocity suddenly changed (400 ms before its arrival on the target) from 2 to 1m/s or 3m/s, respectively. Timing accuracy and movement correction after the unexpected velocity change were analysed. The experts were more accurate in the decelerative case (-29 and -124 ms respectively), in the accelerative case (69 and 116 ms respectively), but not in the constant velocity case (2 and 13 ms respectively). Findings can be explained by the shorter visuo-motor delay (VMD: the time required to adapt the movement to the new velocity) for the experts (162 ms) than for the non-experts (221 ms). This shorter VMD offers more time to adapt the interceptive movement to the new velocity. These results can be interpreted as an optimization of the perception-action coupling with expertise.     

Prospective strategies underlie the control of interceptive actions

The purpose of this study was to test whether a constant bearing angle strategy could account for the displacement regulations produced by a moving observer when attempting to intercept a ball following a curvilinear path. The participants were asked to walk through a virtual environment and to change, if (deemed) necessary, their walking speed so as to intercept a moving ball that followed either a rectilinear or a curvilinear path. The results showed that ball path curvature did indeed influence the participants' displacement kinematics in a way that was predicted by adherence to a constant bearing angle strategy mode of control. Velocity modifications were found to be proportional to the magnitude of target curvature with opposing curvatures giving rise to mirror displacement velocity changes. The role of prospective strategies in the control of interceptive action is discussed.     

The effect of priming on interceptive actions

Time constraints in ball sports encourage players to take advantage of any relevant advance information available to prepare their actions. Advance information, therefore, can serve to prime movement parameters (e.g. movement direction) and reduce the amount of time required to prepare the upcoming movement. Regularly, however, players face situations in which the information used to prepare the action turns out to be outdated just prior to movement initiation and the prepared action needs to be changed as soon as possible. The aim of the experiment presented here was to determine whether the priming effect, generally reported for reaction time tasks, could be generalised to interceptive actions. A secondary aim was to examine the strategies employed by the participants to cope with valid, invalid, or no advance information. The results indicate that, when available, the participants used advance information to prepare their movements. More specifically, in comparison with valid advance information, hit rate and spatial accuracy were reduced when the participants had no advance information and were even smaller when the information conveyed was invalid. The results also suggest that in the absence of valid advance information, the strategies employed to intercept the moving target were tuned to the time remaining until the interception was due to occur.     

Muscular proprioception contributes to the control of interceptive actions

The authors proposed a model of the control of interceptive action over a ground plane (Chardenon, Montagne, Laurent, & Bootsma, 2004). This model is based on the cancellation of the rate of change of the angle between the current position of the target and the direction of displacement (i.e., the bearing angle). While several sources of visual information specify this angle, the contribution of proprioceptive information has not been directly tested. In this study, the authors used a virtual reality setup to study the role of proprioception when intercepting a moving target. In a series of experiments, the authors manipulated proprioceptive information by using the tendon vibration paradigm. The results revealed that proprioception is crucial not only to locate a moving target with respect to the body but also, and more importantly, to produce online displacement velocity changes to intercept a moving target. These findings emphasize the importance of proprioception in the control of interceptive action and illustrate the relevance of our model to account for the regulations produced by the participants.     

Manipulating informational constraints shapes movement reorganization in interceptive actions

Movement organization of cricket batters' actions was analyzed under three distinct experimental task constraints: a representative condition of a practice context in which the batters batted against a "live" bowler, a ball projection machine, and a near life-size video simulation of a bowler. Results showed that each distinct set of task constraints led to significant variations in the patterns of movement control. Removal of advanced information sources from a bowler's actions when the batters faced the ball projection machine caused significant delays in movement initiation, resulting in reduced peak bat swing velocities and a reduction in the quality of bat-ball contact, when compared with batting against a "live" bowler. When responding to a two-dimensional video simulation, batters were able to use information from the bowlers' action, enabling fidelity of initial behavioral responses consistent with the task of batting against a "live" bowler. However, without interceptive task requirements or actual ball flight information, significant variations in downswing initiation timing and peak bat velocities were demonstrated. Findings stress the need for representative experimental and learning designs in fast ball sports for developing performers.     

Indirect interception actions by blind and visually impaired perceivers: Echolocation for interceptive actions

Vernat, J.-P. & Gordon, M. S. (2010). Indirect interception actions by blind and visually impaired perceivers: Echolocation for interceptive actions. Scandinavian Journal of Psychology, 51, 75–83.
This research examined the acoustic information used to support interceptive actions by the blind. Congenitally blind and severely visually impaired participants (all wearing an opaque, black eye-mask) were asked to listen to a target ball rolling down a track. In response, participants rolled their own ball along a perpendicular path to intercept the target. To better understand what information was used the echoic conditions and rolling dynamics of the target were varied across test sessions. In addition the rolling speed of the target and the distance of the participant from the target were varied across trials. Results demonstrated that participants tended to perform most accurately at moderate speeds and distances, overestimating the target's arrival at the fastest speed, and underestimating it at the slowest speed. However, changes to the target's dynamics, that is, the amount of deceleration it underwent on approach, did not strongly influence performance. Echoic conditions were found to affect performance, as participants were slightly more accurate in conditions with faster, higher-intensity echoes. Based on these results blind individuals in this research seemed to be using spatial and temporal cues to coordinate their interceptive actions.     

Children's predictions of consistency in people's actions

Past research suggests that young children are often reluctant to generalize about people's behavior. Three experiments involving 102 4-5-year-olds, 84 7-8-year-olds, and 107 adults explored the conditions under which inductive inferences about people are made. There was an age-based increase in propensity to predict consistency in psychological/intentional causal relations. Children often predicted change; people would behave differently in the future than they did in the past. Younger children limited predictions of consistency to non-psychological contexts. Older children showed some appreciation of stable motivations (e.g. traits, preferences). The results are consistent with the hypothesis that children's theories of mind emphasize situational influences, with personal influences appearing in middle-childhood.     

Informational constraints shape emergent functional behaviours during performance of interceptive actions in team sports

Objectives

This study aimed to explain how defenders intercept the trajectory of a passing ball by understanding how they coupled their actions to critical information sources in a competitive performance setting in team sports.

Design

Time series data on movement displacements of fifteen senior male futsal performers were recorded and digitized during nine competitive futsal games.

Method

Performance was recorded by a digital camera and digitized with TACTO software. The spatial-temporal dynamics of performers during ten intercepted and ten non-intercepted passes were compared. Time to ball interception was calculated by the difference between the time of each defender to an interception point in ball trajectory and the time of the ball’s arrival at the same interception point. Initial distances between defenders and ball and velocity data of defenders and ball over time were also recorded.

Results

Time to ball interception revealed positive values when passes were not intercepted, and negative to zero values when passes were intercepted. At the moment of pass initiation defenders’ distances to the ball constrained their possibilities for successful interception. Analysis of defenders’ adaptations to the environment revealed that continuous changes in the defenders’ velocities constrained their success of the interception.

Conclusions

Intercepted passes seemed to be influenced by the continuous regulation of a defender’s velocity relative to the ball’s trajectory. Time to ball interception is a variable that captured the emergent functional behaviours of players attempting to intercept the trajectory of a pass in the team sport of futsal.     

Reprogramming of interceptive actions: time course of temporal corrections for unexpected target velocity change

The authors investigated the time course of reprogramming of the temporal dimension of motor acts in a task requiring interception of a moving target. The target moved at a constant velocity on a monitor screen; in part of the trials, target velocity was unexpectedly increased or decreased. Those modifications were produced at different moments during target displacement, leaving periods of time from 100 to 800 ms for movement timing correction. The authors assessed the effects of probability of target velocity change (25% vs. 50%), uncertainty about direction of velocity change (unidirectional vs. bidirectional), and direction of velocity change (increase vs. decrease). Analysis of 24 participants' arm acceleration showed that fast adjustments took place between 100 and 200 ms after target velocity change similarly for all uncertainty conditions. Analysis of temporal error indicated that the combination of high probability of target velocity change and certainty on direction of target velocity change led to the most successful movement timing reprogramming. For the other experimental conditions, temporal accuracy was still poor when a period of 800 ms was available for correction. Movement reprogramming was a continuous process that was more efficient for target velocity increase than for target velocity decrease.     

Formalising a hypothesis for the development of anticipatory skill in time-constrained interceptive actions: Implications for the design of junior sport

When professional athletes strike a ball in tennis, cricket or baseball, the high temporal demands often necessitate the need to exploit pre-ball-flight information in order to anticipate the ball's trajectory. Despite the wealth of research probing anticipatory behaviour in sport, our understanding of when, how or why anticipatory skill develops is limited. In this article, we sought to formalise a hypothesis on the development of anticipatory skill. Using empirical temporal data from tennis, cricket and baseball, we propose that the temporal demands of the task dictate an athlete's propensity to anticipate. We then outline the implications of this hypothesis as it relates to junior sport. Notably, we question whether current playing dimensions in junior sport impose temporal demands that are sufficient to elicit anticipatory behaviour. Using tennis, cricket and baseball as examples, we illustrate differences in temporal demands between the junior and professional game and present implications for anticipation. Our discussion challenges the current junior sport experience as it relates to developing anticipatory skill.     

Children's use ofGet passives

Children's use ofget in passivelike constructions was examined in this study. Fifty-eight children at three age levels were tested twice on imitation, comprehension, and production tasks. For the imitation and comprehension tasks, passive sentences withget were modeled in one instance and withbe in the other instance. On both tasks, children performed significantly better on theget items than on thebe items. For the production tasks, active sentences were used as the experimental stimuli. Among 928 production responses possible, children produced 423get passives and 6be passives. The frequency ofget passives increased with increasing age. Qualitative analyses were performed to determine agerelated changes in the pattern of linguistic strategies chosen. These data were consistent with predictions derived from a model of lexical directionality: Children used moreget thanbe passives and more truncated than full passives.     

Areas of use of patient-centered actions

Various forms of patient-centered actions (acceptive listening, paraphrasing, verbalisation of emotional experience), their effects and their possible modes of action are described. The importance of the verbal encoding of prereflexive experience for counselling is dealt with at some length because it generally receives too little attention. The interview and counselling, which are special forms of patient-centered activity, are used as examples to show that patient-centered techniques should be varied to suit the purpose of concrete interactions and therapy sessions.     

Children's strategy use in computational estimation.

This study reports an investigation of ten-year-old children's strategy use in computational estimation (i.e., give an approximate answer like 400 to an arithmetic problem like 224 + 213). Children used four strategies: rounding with decomposition, rounding without decomposition, truncation, and compensation. Strategies appeared to differ in frequency and effectiveness. Finally, children chose strategies in an adaptive way so as to obtain fast and accurate performance. Implications of these findings for understanding children's computational estimation performance and strategies in numerical cognition in general are discussed.     

Children's use of geometry for reorientation

Research on navigation has shown that humans and laboratory animals recover their sense of orientation primarily by detecting geometric properties of large-scale surface layouts (e.g. room shape), but the reasons for the primacy of layout geometry have not been clarified. In four experiments, we tested whether 4-year-old children reorient by the geometry of extended wall-like surfaces because such surfaces are large and perceived as stable, because they serve as barriers to vision or to locomotion, or because they form a single, connected geometric figure. Disoriented children successfully reoriented by the shape of an arena formed by surfaces that were short enough to see and step over. In contrast, children failed to reorient by the shape of an arena defined by large and stable columns or by connected lines on the floor. We conclude that preschool children's reorientation is not guided by the functional relevance of the immediate environmental properties, but rather by a specific sensitivity to the geometric properties of the extended three-dimensional surface layout.     

Children's use of geometric information in mapping tasks

Accumulating evidence, particularly from research using the disorientation technique, demonstrates early sensitivity to geometric properties of space. However, it is not known whether children can use geometric cues to interpret a map. The current study examined how 3- to 6-year-olds use geometric features of layouts in solving mapping tasks. Children were asked to identify a target location in a layout shaped as an isosceles triangle by using information provided in a picture of that layout. Performance depended on whether the shape was presented explicitly or needed to be inferred. Younger participants performed better when the triangle was formed by continuous connected lines than when it was formed by separate objects. Performance also depended on the type of geometric cues available. Children found it easier to establish mapping for targets located in the unique corner of the triangle than for targets located in equal-sized corners. Overall, the findings reveal both a remarkable early ability to use geometric information in mapping and limits in this ability.     

Children's use of verbal collaterals in DRL performance

This study examines the effects of a verbal collateral (counting) on a series of three differential reinforcement of low rates of response (DRL) tasks with progressively longer interresponse time requirements (DRL-2, DRL-6 and DRL-12). Forty-eight 10-year-old children, divided according to sex and conceptual tempo (fast-inaccurate vs. slow-accurate) participated in DRL training, half of them being instructed to count aloud between responses. Counting was found to be related to faster learning of all the tasks and to greater efficiency in obtaining reinforcement in most cases. It also eliminated differences due to sex and conceptual tempo except in DRL-12. However, it had the disadvantage of causing inexact temporal discrimination. The results were replicated in a group of 8-year-old subjects performing the same tasks.     

Multiple information sources in interceptive timing

This study was designed to explore the limitations of tau (τ) as an explanatory construct for the timing of interceptive action. This was achieved by examining the effects of environmental structure and binocular vision on the timing of the grasp in a simple one-handed catch. In two experiments, subjects were required to catch luminous balls of different diameters (4, 6, 8 and 10 cm) in a completely darkened room. In the first experiment the influence of the presence vs. absence of an environmental background structure (both under monocular viewing) was tested, and in the second experiment the influence of monocular vs. binocular vision was examined. It was found that irrespective of the presence of environmental structure, an effect of ball size occurred in the monocular viewing conditions. That is, in monocular viewing conditions the grasp was initiated and completed earlier for the larger balls as compared to the smaller ones, while in the binocular viewing condition subjects behaved in accordance with a constant time to contact strategy: no effects of ball size were found. It is concluded that under binocular viewing a binocular information source is used, while in the monocular viewing condition a lower order information source like image size or image velocity is probably involved.     

Perceptual information for the timing of interceptive action

Time-to-contact is an important quantity for controlling activities which involve the timing of interactions with objects and surfaces in motion relative to an observer. Two alternative means for obtaining perceptual information that might be used to obtain the time-to-contact required to correctly time an interaction have been contrasted: a method based on the perception of distance and velocity, and a method due to Lee involving a perceptual variable called tau. A monocular version of the first method is presented and shown to place a highly unrealistic and arbitrary limitation on the capabilities of the visual system. The second method is reviewed and its limitations discussed. Several means by which these limitations can be overcome are presented. Recently reported results from experiments which involved catching self-luminous balls in the dark are interpreted in terms of timing information available to the subject, and the notions of intermodal and multimodal timing information are introduced. Finally, the possibility that timing information is available to an observer which does not involve the variable tau is considered. It is concluded that many questions regarding the perception of time-to-contact remain unresolved and that much empirical research remains to be done.     

Children's use of language context in lexical ambiguity resolution

Lexical ambiguity resolution was examined in children aged 7 to 10 years and adults. In Experiment 1, participants heard sentences supporting one (or neither) meaning of a balanced ambiguous word in a cross-modal naming paradigm. Naming latencies for context-congruent versus context-incongruent targets and judgements of the relatedness of targets to the sentence served as indices of appropriate context use. While younger children were faster to respond to related targets regardless of the sentence context, older children and adults showed priming only for context-appropriate targets. In Experiment 2, only a single-word context preceded the homophone, and in contrast to Experiment 1, all groups showed contextual sensitivity. Individual working-memory span and inhibition ability were also measured in Experiment 2, and more mature executive function abilities were associated with greater contextual sensitivity. These findings support a developmental model whereby sentential context use for lexical ambiguity resolution increases with age, cognitive processing capacity, and reading skill.