Aiming Task Research Articles

Submovement control processes in discrete aiming as a function of space-time constraints.

There is preliminary evidence that there are several types of submovements in movement aiming that reflect different processes of control and can result from particular task constraints. The purpose of the study was to investigate the effect of movement space and time task criteria on the prevalence of different submovement control characteristics in discrete aiming. Twelve participants completed 3 distance x 5 time conditions each with 100 trials in a target-aiming movement task. The kinematic structure of the trajectory determined the prevalence of 5 submovement types (none; pre-peak, post-peak movement velocity; undershoot, overshoot). The findings showed that the overall number of submovements increased in the slower space-time conditions and was predominantly characterized by post-peak trajectory submovements rather than discrete overshoot submovements. Overshoot submovements were more frequent in the high average movement velocity and short time duration conditions. We concluded that there are qualitatively different distributional patterns of submovement types in discrete aiming tasks that are organized by the quantitative scaling of the average movement velocity arising from multiple control processes to meet the specific space-time task constraints.

Search Strategies in Practice: Movement Variability Affords Perception of Task Dynamics

ABSTRACTPractice has been conceptualized in terms of a search process through an evolving perceptual-motor workspace. The experiment was set up to examine whether the inherent variability of the system would influence perception of the relevant properties of the task space. We reanalyzed the data from Hsieh, Liu, Mayer-Kress, and Newell (2013) in which participants performed a speed-accuracy aiming task and feedback emphasized either temporal or spatial accuracy in different conditions. The maximum variability in spatial error during practice differentiated individual's best performance in the fast speed-accuracy conditions. Additionally, we found that a threshold of variability predicted discontinuities during practice within individuals. The findings support the proposition that inherent variability affords perception of the relevant dimension of the task. The search motion through the perceptual-motor workspace was continuous or discontinuous depending on the constraints of the movement speed-accuracy condition.

Visual Illusions Affect Motor Performance, But not Learning in Highly Skilled Shooters

Enhanced expectancies are an important component of OPTIMAL theory and are thought to contribute to motor performance and learning. There is limited information, however, on the generalizability of OPTIMAL theory to highly skilled individuals. The purpose of this study was to examine the effects of visual illusions, specifically an Ebbinghaus illusion, on the performance and learning of an aiming task using highly skilled 10-m rifle and pistol shooters. Two groups of shooters with international experience were recruited and practiced with perceived larger and smaller targets. Our results indicated that participants who perceived the target larger reported higher self-efficacy immediately after practice. In addition, these participants had higher shooting performance during practice. Our retention test (24 hours later), however, did not produce differences in self-efficacy or shooting performance. Our data suggests that visual illusions are beneficial for motor performance in highly skilled shooters, but may not affect learning in those who are in the latter stages of learning. Further studies should continue examining the role of visual illusions for enhancing expectancies in highly skilled and experienced performers.

Distinct coordinate systems for adaptations of movement direction and extent.

Learned compensations for perturbed visual feedback of movement extent and direction generalize differently to unpracticed movement directions, which suggests different underlying neural mechanisms. Here we investigated whether gain and rotation adaptations are consistent with representation in different coordinate systems. Subjects performed a force-aiming task with the wrist and learned different gains or rotations for different force directions. Generalization was tested without visual feedback for the same extrinsic directions but with the forearm in a different pronation-supination orientation. When the change in forearm orientation caused the adapted visuomotor map to conflict in extrinsic and joint-based coordinates, rotation generalization occurred in extrinsic coordinates but with reduced magnitude. In contrast, gain generalization appeared reduced and phase shifted. When the forearm was rotated further, such that all imposed perturbations aligned in both joint-based and extrinsic coordinates in both postures, rotation generalization was further reduced, whereas there was neither reduction nor phase shift in the pattern of extent generalization. These results show that rotation generalization was expressed in extrinsic coordinates, and that generalization magnitude was modulated by posture. In contrast, gain generalization appeared to depend on target direction defined by an integrated combination of extrinsic and joint-based coordinates and was not reduced substantially by posture changes alone. Although the quality of the model fit underlying our interpretation prevents us from making strong conclusions, the data suggest that adaptations of movement direction and extent are represented according to distinct coordinate systems.NEW & NOTEWORTHY Visuomotor gain and rotation adaptations generalize differently to novel movement directions, which suggests different neural mechanisms. When extrinsic and joint-based coordinates are effectively dissociated in an isometric aiming task, we find that they also generalize in different coordinate systems. Specifically, rotation generalized in extrinsic coordinates and decayed as posture departed from that adopted during adaptation. In contrast, gain generalization was expressed according to mixed extrinsic/joint-based coordinates and was not substantially reduced by postural changes.

Evaluation of speed-accuracy trade-off in a computer task in individuals with cerebral palsy: a cross-sectional study

BackgroundIndividuals with Cerebral Palsy (CP) present with sensorimotor dysfunction which make the control and execution of movements difficult. This study aimed to verify the speed-accuracy trade-off in individuals with CP.MethodsForty eight individuals with CP and 48 with typical development (TD) were evaluated (32 females and 64 males with a mean age of 15.02 ± 6.37 years: minimum 7 and maximum 30 years). Participants performed the “Fitts’ Reciprocal Aiming Task v.1.0 (Horizontal)” on a computer with different sizes and distance targets, composed by progressive indices of difficulty (IDs): ID2, ID4a and ID4b.ResultsThere were no statistical differences between the groups in relation to the slope of the curve (b1) and dispersion of the movement time (r2). However, the intercept (b0) values presented significant differences (F(1.95) = 11.3; p = .001]), with greater movement time in the CP group compared to the TD group. It means that for individuals with CP, regardless of index difficulty, found the task more difficult than for TD participants. Considering CP and TD groups, speed-accuracy trade-off was found when using different indices of difficulty (ID2 and ID4). However, when the same index of difficulty was used with a larger target and longer distance (ID4a) or with a narrow target and shorter distance (ID4b), only individuals with CP had more difficulty performing the tasks involving smaller targets. Marginally significant inverse correlations were identified between the values of b1 and age (r = −0.119, p = .052) and between r2 and Gross Motor Function Classification System (r = −0.280, p = .054), which did not occur with the Manual Ability Classification System.ConclusionWe conclude that the individuals with CP presented greater difficulty when the target was smaller and demanded more accuracy, and less difficulty when the task demanded speed. It is suggested that treatments should target tasks with accuracy demands, that could help in daily life tasks, since it is an element that is generally not considered by professionals during therapy.Trial registrationClinicalTrials.gov, NCT03002285, retrospectively registered on 20 Dec 2016.

Increased Complexities in Visual Search Behavior in Skilled Players for a Self-Paced Aiming Task.

The badminton serve is an important shot for winning a rally in a match. It combines good technique with the ability to accurately integrate visual information from the shuttle, racket, opponent, and intended landing point. Despite its importance and repercussive nature, to date no study has looked at the visual search behaviors during badminton service in the singles discipline. Unlike anticipatory tasks (e.g., shot returns), the serve presents an opportunity to explore the role of visual search behaviors in movement control for self-paced tasks. Accordingly, this study examined skill-related differences in visual behavior during the badminton singles serve. Skilled (n = 12) and less skilled (n = 12) participants performed 30 serves to a live opponent, while real-time eye movements were captured using a mobile gaze registration system. Frame-by-frame analyses of 662 serves were made and the skilled players took a longer preparatory time before serving. Visual behavior of the skilled players was characterized by significantly greater number of fixations on more areas of interest per trial than the less skilled. In addition, the skilled players spent a significantly longer time fixating on the court and net, whereas the less skilled players found the shuttle to be more informative. Quiet eye (QE) duration (indicative of superior sports performance) however, did not differ significantly between groups which has implications on the perceived importance of QE in the badminton serve. Moreover, while visual behavior differed by skill level, considerable individual differences were also observed especially within the skilled players. This augments the need for not just group-level analyses, but individualized analysis for a more accurate representation of visual behavior. Findings from this study thus provide an insight to the possible visual search strategies as players serve in net-barrier games. Moreover, this study highlighted an important aspect of badminton relating to deception and the implications of interpreting visual behavior of players.

Adults With Down Syndrome Demonstrate Peripheral, Not Central, Deficits When Integrating Movements During Multiple-Target Sequences

The perceptual-motor impairments of individuals with Down syndrome (DS) are attributed to central (e.g., neurophysiology deficits that affect the retrieval or initiation of motor programs) and peripheral (e.g., anatomical deficits relating to issues with inertia of limb mechanics and muscle organization) processes. However, recent research suggests that central deficits do not affect the integration between movements. We investigate the impact of central and peripheral DS deficits on movement integration by examining the planning and execution of multiple-target multiple-arm movements. Individuals with DS, typically developing (TD), and individuals with an undifferentiated intellectual disability (UID) completed five aiming tasks: a one target; a one-arm, two-target extension; a two-arm, two-target extension (movement one was performed with one arm and movement two performed with the other); a one-arm, two-target reversal; and a two-arm, two-target reversal. Movement times (MTs) to the first target were longer in the two-target tasks compared with the one-target task. For the one-arm, two-target reversal task, this effect emerged only in individuals with DS. These results indicate that individuals with DS use central processing for movement integration similarly to their TD and UID counterparts but cannot exploit peripheral-level integration to enhance integration in one-arm reversal tasks.

Index of difficulty and side of space are accommodated during the selection and planning of a joint action

Co-actors can facilitate the achievement of a shared goal by accurately anticipating each other’s needs and subsequently planning actions to accommodate those needs. The purpose of the present study was to determine if co-actors plan and execute their movements to accommodate the difficulty of their partners’ action. We hypothesized that information derived from shared task representations could influence the simulation of other’s actions and that motor experience would enhance the ability of co-actor’s to anticipate their co-actor’s needs. Partners performed a sequential aiming task. The initiator of the sequential action placed a dowel on a line between two potential targets that varied in size across trials. The initiator did not know the actual target location prior to placing the dowel. The finisher then grasped the dowel and moved it to whichever target was signaled, from wherever their partner had placed the dowel. Participants completed the partner task before and after completing an individual task in which they completed both the initiating and the finishing movements. Consistent with the prediction that co-actors represent the difficulty of their partners’ actions, the dowel was placed closer to the smaller target of a pair. Further, it was found that motor experience influenced dowel placement – there was a shift in dowel placement following the completion of the individual task. These results indicate that co-actors plan their movements based on features of their co-actor’s movements and that motor experience provides information that allows people to better plan movements for their partners.

The Role of Consistent Context in Rapid Movement Planning: Suboptimal Endpoint Adjustment to Changing Rewards

ABSTRACTThe authors' purpose was to determine if participants adjusted their endpoint during a rapid aiming task in the context of changing rewards and whether participants needed consistent feedback to do so. Participants aimed to a target that was overlapped by a penalty region. Participants gained points for hitting the target but lost points for hitting the penalty region. The reward value associated with target contact either changed trial to trial, reducing consistent feedback (variable condition) or changed between blocks of trials (blocked condition) with the repetition of reward value within a block increasing the consistency of feedback. Participants adjusted their endpoints with changing reward value in the blocked but not variable condition indicating consistent feedback is needed to adjust endpoint to changing rewards.

사격 조준 과제 시 숙련성에 따른 압력중심의 복잡성과 양 발의 체중 부하 비교

사격 조준 과제 시 숙련성에 따른 압력중심의 복잡성과 양 발의 체중 부하 비교

Do accuracy requirements change bimanual and unimanual control processes similarly?

Unimanual (left and right limbs) and bimanual (in-phase) reciprocal aiming tasks were tested to determine if the control processes used to perform the unimanual aiming tasks were also present in bimanual aiming tasks. Participants were asked to move a cursor as quickly and accurately as possible between the two targets presented in a Lissajous feedback display. The size of the targets created indexes of difficulty (ID) of 3, 4, 5, and 6 and the position of the targets created bimanual and unimanual conditions. The results indicated that, as ID increased, the end-effectors' motion gradually switched from a cyclical to a more discrete motion for both unimanual and bimanual aiming tasks. However, the transition in control processes (i.e., the transition between cyclical and more discrete motions) tended to occur at a lower ID for the bimanual than the unimanual aiming tasks. Results also indicated that at ID6, bimanual aiming tasks were performed slower, more variable, and right limb dwelled at the targets longer than in the unimanual aiming task. No differences in performance were detected between the unimanual (left and right) and bimanual conditions at IDs 3-5. In terms of bimanual coordination, increasing the accuracy requirement resulted in decreased relative phase bias, but not more stable coupling between the two limbs.

The effects of perception-action coupling on perceptual decision-making in a self-paced far aiming task.

The effects of perception-action coupling on perceptual decision-making in a self-paced far aiming task.

Practice Makes Efficient: Cortical Alpha Oscillations Are Associated With Improved Golf Putting Performance.

Practice of a motor skill results in improved performance and decreased movement awareness. The psychomotor efficiency hypothesis proposes that the development of motor expertise through practice is accompanied by physiological refinements whereby irrelevant processes are suppressed and relevant processes are enhanced. The present study employed a test–retest design to evaluate the presence of greater neurophysiological efficiency with practice and mediation analyses to identify the factors accounting for performance improvements, in a golf putting task. Putting performance, movement-specific conscious processing, electroencephalographic alpha power and alpha connectivity were measured from 12 right-handed recreational golfers (age: M = 21 years; handicap: M = 23) before and after 3 practice sessions. As expected, performance improved and conscious processing decreased with training. Mediation analyses revealed that improvements in performance were partly attributable to increased regional gating of alpha power and reduced cross-regional alpha connectivity. However, changes in conscious processing were not associated with performance improvements. Increased efficiency was manifested at the neurophysiological level as selective inhibition and functional isolation of task-irrelevant cortical regions (temporal regions) and concomitant functional activation of task-relevant regions (central regions). These findings provide preliminary evidence for the development of greater psychomotor efficiency with practice in a precision aiming task.

Interaction of Perception and Action in Discrete and Continuous Rapid Aiming Tasks

ABSTRACTPreviously, we have shown that discrete and continuous rapid aiming tasks are governed by distinct visuomotor control mechanisms by assessing the combined visual illusion effects on the perceived and effective index of difficulty (ID). All participants were perceptually biased by the combined visual illusion before they performed the rapid aiming tasks. In the current study, the authors manipulated the order of performing perceptual and motor tasks to examine whether perceptual or motor experience with the illusory visual target would influence the subsequent perceived and effective ID in discrete and continuous tapping tasks. The results supported our hypothesis showing that perceptual experience with the illusory visual target in the discrete condition reduced the effective ID in the subsequent discrete tapping task, and motor experience with the illusory visual target in the continuous condition reduced the illusion effects on the perceived ID in the subsequent perceptual judgment task. The study demonstrates the coinfluence of perception and action, and suggests that perception and action influence one another with different magnitude depending on the spatial frame of reference used to perform the perceptuomotor task.

The aging brain: Movement speed and spatial control

Background/Objectives: With aging, people commonly develop motor slowing (bradykinesia). Although this slowness with aging may be entirely related to degradation of the cerebral networks important in motor programing, it is possible that, at least in part, it may be a learned procedure for enhancing the accuracy and/or precision of movements. The goal of this study is to test these contradictory hypotheses. Methods: Twenty-four healthy adults, 12 younger than age 26 and 12 older than age 65 were asked to make alternative marks with a pen between a card centered in front of them and a series of circles distributed across a page. Performance was timed, and participants were instructed to complete the task as quickly as possible while not sacrificing accuracy for speed. The circle sizes and hand used varied by trial. Results: The older adults performed the task more slowly for all target circle diameters. As the circles decreased in size, the younger adults performed the task more rapidly than did the older participants, but the younger participants also had a greater decline in accuracy. Conclusions: During this aiming task, healthy older adults were less likely than younger adults to sacrifice accuracy for speed. Thus, at least in part, their slowing may be a learned adaptive strategy.

MAXFAS: Mechatronic Arm Exoskeleton for Firearm Aim Stabilization

This article details the design, fabrication, and application of a mechatronic arm exoskeleton for firearm aim stabilization (MAXFAS), which senses and damps involuntary tremors in the arm. Human subject experiments were carried out using the device in a simulated shooting and aiming task. Results indicate that MAXFAS reduced arm tremors and improved shooting performance while wearing the device. Residual performance improvement after removing the device and possible training function of MAXFAS will also be discussed.

Strength Training Biases Goal-Directed Aiming.

Goal-directed movements tend to resemble the characteristics of previously executed actions. Here we investigated whether a single bout of strength training, which typically involves stereotyped actions requiring strong neural drive, can bias subsequent aiming behavior toward the direction of trained forces. In experiment 1 (n = 10), we tested the direction of force exerted in an isometric aiming task before and after 40 repetitions of 2-s maximal-force ballistic contractions toward a single directional target. In experiment 2 (n = 12), each participant completed three training conditions in a counterbalanced crossover design. In two conditions, both the aiming task and the training were conducted in the same (neutral) forearm posture. In one of these conditions, the training involved weak forces to determine whether the level of neural drive during training influences the degree of bias. In the third condition, high-force training contractions were performed in a 90° pronated forearm posture, whereas the low-force aiming task was performed in a neutral forearm posture. This dissociated the extrinsic training direction from the pulling direction of the trained muscles during the aiming task. In experiment 1, we found that aiming direction was biased toward the training direction across a large area of the work space (approximately ±135°; tested for 16 targets spaced 22.5° apart), whereas in experiment 2, we found systematic bias in aiming toward the training direction defined in extrinsic space, but only immediately after high-force contractions. Our findings suggest that bias effects of training involving strong neural drive generalize broadly to untrained movement directions and are expressed according to extrinsic rather than muscle-based coordinates.

Extending Energy Optimization in Goal-Directed Aiming from Movement Kinematics to Joint Angles

ABSTRACTEnergy optimization in goal-directed aiming has been demonstrated as an undershoot bias in primary movement endpoint locations, especially in conditions where corrections to target overshoots must be made against gravity. Two-component models of upper limb movement have not yet considered how joint angles are organized to deal with the energy constraints associated with moving the upper limb in goal-directed aiming tasks. To address this limitation, participants performed aiming movements to targets in the up and down directions with the index finger and two types of rod extensions attached to the index finger. The rod extensions were expected to invoke different energy optimizing strategies in the up and down directions by allowing the distal joints the opportunity to contribute to end effector displacement. Primary movements undershot the farthest target to a greater extent in the downward direction compared to the upward direction, showing that movement kinematics optimize energy expenditure in consideration of the effects of gravity. As rod length increased, shoulder elevation was optimized in movements to the far-up target and elbow flexion was optimally minimized in movements to the far-down target. The results suggest energy optimization in the control of joint angles independent of the force of gravity.

Characterization of graphomotor functions in individuals with Parkinson's disease and essential tremor.

In this study, we explored the relationship between the clinical features and motor impairments related to the graphomotor function of individuals with Parkinson's disease (PD) and essential tremor (ET). We recruited 46 participants: 12 with PD, 13 with ET, and 21 controls. All participants were asked to perform six graphomotor tasks on a digitizer tablet: drawing straight lines, cursive-connected loops, discrete circles, and continuous circles, and making goal-aimed movements with a stylus in two different directions with three different accuracy constraints. The results showed that although participants with PD were able to draw straight lines slightly faster than controls, they produced cursive-connected loops much slower than controls. In addition, in contrast to controls and individuals with ET, PDs also drew the cursive loops progressively smaller. In the aiming task, we found that equivalent movements with high accuracy constraints were drawn slower by individuals with ET or PD than by controls. However, when performing the equivalent movements with moderate or low accuracy constraints, PDs performed similarly to controls. In contrast to the equivalent movements, PD and ET participants both performed nonequivalent movements slower than controls, no matter the demands arising from the accuracy constraints. The present study shows that simple graphic tasks can differentiate impairments in fine motor function resulting from ET and PD.

Can Visual Illusions Be Used to Facilitate Sport Skill Learning?

ABSTRACTRecently it has been reported that practicing putting with visual illusions that make the hole appear larger than it actually is leads to longer-lasting performance improvements. Interestingly, from a motor control and learning perspective, it may be possible to actually predict the opposite to occur, as facing a smaller appearing target should enforce performers to be more precise. To test this idea the authors invited participants to practice an aiming task (i.e., a marble-shooting task) with either a visual illusion that made the target appear larger or a visual illusion that made the target appear smaller. They applied a pre–post test design, included a control group training without any illusory effects and increased the amount of practice to 450 trials. In contrast to earlier reports, the results revealed that the group that trained with the visual illusion that made the target look smaller improved performance from pre- to posttest, whereas the group practicing with visual illusions that made the target appear larger did not show any improvements. Notably, also the control group improved from pre- to posttest. The authors conclude that more research is needed to improve our understanding of whether and how visual illusions may be useful training tools for sport skill learning.