Hand Movement Time Research Articles

An Extended Fitts’ Law Model for Hand Interaction Evaluation in Virtual Reality: Accounting for Spatial Variables in 3D Space and the Arm Fatigue Influence

Fitts’ law is a standard tool for assessing user performance and interaction device effectiveness in human-computer interaction (HCI). However, it disregards spatial variables in 3D space and arm fatigue impacts. To address these limitations in evaluating hand interaction performance in virtual reality (VR), a target pointing and acquisition experiment was conducted in which two mapping principles of hand movements (translation, angular rotation) and two interaction methods (hand controller, freehand) were compared. The results indicated that (1) in target acquisition, azimuth and inclination angles exhibited a sinusoidal relationship with hand movement time (MT); (2) arm fatigue significantly affected MT, demonstrating an exponential relationship with task duration; (3) in the case of translational movement mapping, freehand interaction exhibited less influence from fatigue compared to controller interaction; while (4) in the angular rotation mapping case, controller pointing demonstrated greater stability, with fewer declines in efficiency than freehand pointing. Based on the findings, new model formulations were developed to accommodate varying conditions.

Timing of eye and hand movements during reaching depends on functional demands of gaze

Timing of eye and hand movements during reaching depends on functional demands of gaze

Intermuscular coherence reveals that affective emotional pictures modulate neural control mechanisms during the initiation of arm pointing movements.

Several studies in psychology provided compelling evidence that emotions significantly impact motor control. Yet, these evidences mostly rely on behavioral investigations, whereas the underlying neurophysiological processes remain poorly understood. Using a classical paradigm in motor control, we tested the impact of affective pictures associated with positive, negative or neutral valence on the kinematics and patterns of muscle activations of arm pointing movements performed from a standing position. The hand reaction and movement times were measured and electromyography (EMG) was used to measure the activities from 10 arm, leg and trunk muscles that are involved in the postural maintenance and arm displacement in pointing movements. Intermuscular coherence (IMC) between pairs of muscles was computed to measure changes in patterns of muscle activations related to the emotional stimuli. The hand movement time increased when an emotional picture perceived as unpleasant was presented as compared to when the emotional picture was perceived as pleasant. When an unpleasant emotional picture was presented, beta (β, 15-35 Hz) and gamma (γ, 35-60 Hz) IMC decreased in the recorded pairs of postural muscles during the initiation of pointing movements. Moreover, a linear relationship between the magnitude of the intermuscular coherence in the pairs of posturo-focal muscles and the hand movement time was found in the unpleasant scenarios. These findings reveal that emotional stimuli can significantly affect the content of the motor command sent by the central nervous system to muscles when performing voluntary goal-directed movements.

The Effect of 3D TVs on Eye Movement and Motor Performance

Three-dimensional TVs have been commercialized in recent few years; however, poor visual and motor performances may have an impact on consumer acceptance of 3D TVs. The purpose of this study was to investigate the effects of 3D TVs on eye movement and motor performance. Specifically, the effect of stereoscopic display parallax of 3D TVs and movement task index of difficulty (ID) on eye movement was investigated. In addition, the effect of stereoscopic display parallax of 3D TVs and movement task ID on motor performance was also investigated. Twelve participants voluntarily participated in a multi-directional tapping task under two different viewing environments (2D TV and 3D TV), three different levels of stereoscopic depth (140, 190, 210 cm), and six different Index of Difficulty levels (2.8, 3.3, 3.7, 4.2, 5.1, 6.1 bit). The study revealed that environment had significant effects on eye movement time, index of eye performance, eye fixation accuracy, number of fixations, time to first fixation, saccadic duration, revisited fixation duration, hand movement time, index of hand performance, and error rate. Interestingly, there were no significant effects of stereoscopic depth on eye movement and motor performance; however, the best performance was found when the 3D object was placed at 210 cm. The main novelty and contributions of this study is the in-depth investigations of the effect of 3D TVs on eye movement and motor performance. The findings of this study could lead to a better understanding of the visual and motor performance for 3D TVs.

Hand Grip Strength Vs. Locomotor Efficiency in Sitting Volleyball Players.

The objective of this paper was to determine the relationship between hand grip strength and movement time (locomotor efficiency in a seated position using the upper and lower extremities) in sitting volleyball players. In addition, a comparison was made between the velocity curves for forward and backward locomotion. Nine male members of the sitting volleyball team participated in the study. Hydraulic and spring manual dynamometers were used to measure hand grip strength. Movement times were registered for distances of 1, 2, 3, 4, 5, 6 and 10-m with the use of the Smart Speed System photocells. Significant relationships between hand grip strength of the left (rs=-0.78) and right (rs=-0.73) hands and the forward movement time over a distance of 1-m were found. Hand grip strength had no significant relationship with either forward movement times at other distances or backward movement times. Results suggest that hand strength is linked to locomotor efficiency of sitting volleyball players. High hand grip strength makes the start easier by pushing away from the ground with the upper limbs.

Predicting Clinically Significant Improvement After Robot-Assisted Upper Limb Rehabilitation in Subacute and Chronic Stroke.

Prior studies examining predictors of favorable clinical outcomes after upper limb robot-assisted therapy (RT) have many shortcomings. Therefore, the aim of this study was to identify meaningful predictors and a prediction model for clinically significant motor improvement in upper limb impairment after RT for each stroke phase. This retrospective, single-center study enrolled patients with stroke who received RT using InMotion2 along with conventional therapy (CT) from January 2015 to September 2019. Demographic characteristics, clinical measures, and robotic kinematic measures were evaluated. The primary outcome measure was the Fugl-Meyer Assessment-Upper Extremity (FMA-UE) and we classified patients with improvement more than the minimal clinically important difference as responders for each stroke phase. Univariable and multivariable logistic regression analyses were performed to assess the relationship between potential predictors and RT responders and determine meaningful predictors. Subsequently, meaningful predictors were included in the final prediction model. One hundred forty-four patients were enrolled. The Hand Movement Scale and time since onset were significant predictors of clinically significant improvement in upper limb impairment (P = 0.045 and 0.043, respectively), as represented by the FMA-UE score after RT along with CT, in patients with subacute stroke. These variables were also meaningful predictors with borderline statistical significance in patients with chronic stroke (P = 0.076 and 0.066, respectively). Better hand movement and a shorter time since onset can be used as realistic predictors of clinically significant motor improvement in upper limb impairment after RT with InMotion2 alongside CT in patients with subacute and chronic stroke. This information may help healthcare professionals discern optimal patients for RT and accurately inform patients and caregivers about outcomes of RT.

Eye-hand movement in 3D displays: A structural equation modeling approach

Eye-hand movements are two important parameters to evaluate the User Experience (UX) in the stereoscopic display (3D). The current study utilized structural equation modeling (SEM) to derive the causal relationship between parallax, index of difficulty (ID), eye movement, hand movement, eye index performance (IP eye), and hand index performance (IP hand) simultaneously. 10 participants voluntarily participated in the current study and they were asked to perform a multi-directional Fitts’ Law task in the projection-based stereoscopic display. The results indicated that parallax had significant effects on eye movement time and hand movement time. In addition, ID was found to have significant effects on eye movement time and hand movement time. Interestingly, parallax and ID were found to have significant effects on IP eye, however, no significant effects were found on IP hand. These findings could be very beneficial for UX researchers and projection-based stereoscopic display developers especially in terms of evaluating UX of an interface.

F141. Sensorimotor robotic measures of tDCS and HD-tDCS enhanced motor learning in children

Perinatal stroke causes hemiparetic cerebral palsy (CP) and lifelong disability. Treatments are limited but non-invasive brain stimulation, such as transcranial direct-current stimulation (tDCS) can alter cortical excitability, providing a unique opportunity for therapeutic neuromodulation in CP. We have demonstrated that application of tDCS can enhance motor skill acquisition in children. Growing evidence suggests that tDCS is safe in pediatrics, however refined forms of stimulation such as high-definition (HD)-tDCS have not been applied in children. The KINARM robot objectively quantifies sensorimotor function and holds potential to examine functional changes associated with tDCS-paired motor learning. We aimed to characterize changes in sensorimotor function induced by tDCS and HD-tDCS paired motor learning in children. We hypothesized that application of tDCS and HD-tDCS will improve motor function (visually-guided reaching; VGR), but only tDCS will improve sensory function (position matching). AMPED (Accelerated motor learning in pediatrics) is a randomized, sham-controlled trial (ClinicalTrials.gov: NCT03193580). Healthy, right-handed children (12–18y) were recruited. A validated 4-stage KINARM protocol and a series of motor function assessments [Purdue Pegboard Test (PPT), Jebsen Taylor Test, and Serial Reaction Time Task] were completed at baseline, post-training, and six weeks later. Participants were randomized to receive sham tDCS, anodal tDCS, or anodal HD-tDCS targeting the right primary motor cortex. Over five consecutive days, participants trained their left hand on the PPT during stimulation. Safety and tolerability was assessed daily. Group differences were explored using repeated measure ANOVA with post hoc correcting for multiple comparisons. To date, 15 of 24 participants have completed the study (median 16.4y, range 12–18y, 67% female). Blinded interim analysis of cases grouped by intervention (group A, B, C) was performed on an exploratory basis. All participants improved their left hand PPT scores (p < 0.001) regardless of intervention. The mean improvement in left hand PPT scores was 3.93 ± 1.33 pegs and was comparable across the groups: A 4.33 ± 1.78, B 3.08 ± 1.15, C 3.67 ± 1.18. No difference was observed between the groups. Right hand PPT scores increased (Group A p = 0.009) or were unchanged (both p > 0.06). Position matching performance did not change from baseline to post-training. Group A demonstrated improvements in left hand reaction (p = 0.03) and movement time (p = 0.04) in VGR tasks between baseline and post-training. All procedures were well tolerated with no adverse events reported. Application of tDCS and HD-tDCS in healthy children is safe, feasible, and tolerable. Sensorimotor function may be altered by tDCS and HD-tDCS paired with motor training. Optimizing tDCS and HD-tDCS protocols while exploring mechanisms of action is essential to advance therapeutic applications of tDCS in children with CP and other motor disabilities.

Effects of 2D and 3D image views on hand movement trajectories in the surgeon’s peri-personal space in a computer controlled simulator environment

In image-guided surgical tasks, the precision and timing of hand movements depend on the effectiveness of visual cues relative to specific target areas in the surgeons peri-personal space. Two-dimensional (2D) image views of real-world movements are known to negatively affect both constrained (with tool) and unconstrained(no tool) hand movements compared with direct action viewing. Task conditions where virtual 3D would generate and advantage for surgical eye-hand coordination are unclear. Here, we compared effects of 2D and 3D image views on the precision and timing of surgical hand movement trajectories in a simulator environment. Eight novices had to pick and place a small cube on target areas across different trajectory segments in the surgeons peri-personal space, with the dominant hand, with and without a tool, under conditions of: (1) direct (2) 2D fisheye camera and (3) virtual 3D viewing (headmounted). Significant effects of the location of trajectories in the surgeons peri-personal space on movement times and precision were found. Subjects were faster and more precise across specific target locations, depending on the viewing modality.

Eye Pointing in Stereoscopic Displays

This study investigated eye pointing in stereoscopic displays. Ten participants performed 18 tapping tasks in stereoscopic displays with three different levels of parallax (at the screen, 20 cm and 50 cm in front of the screen). The results showed that parallax had significant effects on hand movement time, eye movement time, index of performance in hand click and eye gaze. The movement time was shorter and the performance was better when the target was at the screen, compared to the conditions when the targets were seen at 20 cm and 50 cm in front of the screen. Furthermore, the findings of this study supports that the eye movement in stereoscopic displays follows the Fitts’ law. The proposed algorithm was effective on the eye gaze selection to improve the good fit of eye movement in stereoscopic displays.

Allocation of attention and dual-task effects on upper and lower limb task performance in healthy young adults.

Many daily activities require separate tasks of the arms and legs to be performed together, as in driving where one foot controls the accelerator, one arm steers, and the other arm and foot shift gears and clutch. Strategies and underlying mechanisms for attention allocation and task prioritization have been explored in standing and walking while performing a manual or cognitive task. These studies reveal a task-related strategy that often, but not always, prioritizes the lower limb task of walking. However, in the absence of locomotion and gait-related postural control, as in sitting, multi-limb dual-task strategies are largely unexplored. Therefore, to characterize dual-task interference of arm and leg tasks during a driving-like activity, seated participants were assessed for the interference effect on hand velocity and movement time of a three-phase reach task and on the error in tracking of a foot-pedal ramp-tracking task. We found that the dual-task cost to reaching shown as decreases in reach performance differed among the three phases, that the cost to foot-pedal tracking also differed by phase, and that the between-task trade-off and prioritization strategy varied between the steep and gradual tracking ramps. Therefore, we propose that attention to concurrent reaching and foot-pedal tracking was flexibly allocated based on phase of the tasks.

Delays in Manual Reaching Are Associated with Impaired Functional Abilities in Early Dementia Patients

Background/Aims: Recent evidence shows that early dementia patients have deficits in manual reaching tasks. It is important to understand the impact of these functional disabilities on their quality of life. The aim of this study was to investigate if there is an association between manual reaching and measures of (instrumental) activities of daily living (IADL) in a group of patients with cognitive complaints. Methods: The manual reaching performance of 27 patients was assessed in detail with eye and hand tracking devices. Patients were divided into three groups based on self-reported loss of IADL function. Parameters describing hand response and movement times were compared between groups. Results: Patients with loss of IADL function in ≥1 domain had delayed hand response and hand movement times towards visible targets compared to patients with no loss of IADL function. Conclusion: Delays in manual reaching movements are related to the degree of loss of IADL function in early dementia patients.

Childhood obesity affects postural control and aiming performance during an upper limb movement

Obesity reduces the efficiency of postural and movement control mechanisms. However, the effects of obesity on a functional motor task and postural control in standing and seated position have not been closely quantified among children. The aim of this study is to examine the effects of obesity on the execution of aiming tasks performed in standing and seated conditions in children. Twelve healthy weight children and eleven obese children aged between 8 and 11 years pointed to a target in standing and seated position. The difficulty of the aiming task was varied by using 2 target sizes (1.0 cm and 5.0 cm width; pointing to the smaller target size needs a more precise movement and constitutes a more difficult task). Hand movement time (MT) and its phases were measured to quantify the aiming task. Mean speed of the center of pressure displacement (COP speed) was calculated to assess postural stability during the movement. Obese children had significantly higher MTs compared to healthy-weight children in seated and standing conditions explained by greater durations of deceleration phase when aiming. Concerning the COP speed during the movement, obese children showed significantly higher values when standing compared to healthy-weight children. This was also observed in the seated position. In conclusion, obesity adds a postural constraint during an aiming task in both seated and standing conditions and requires obese children to take more time to correct their movements due to a greater postural instability of the body when pointing to a target with the upper-limb.

Visual Attention and Saccadic Oculomotor Control in Parkinson's Disease

Background: In patients with Parkinson's disease (PD) we aimed at differentiating the relation between selective visual attention, deficits of programming and dynamics of saccadic eye movements while searching for a target and hand-reaction time as well as hand-movement time. Visual attention is crucial for concentrating selectively on one aspect of the visual field while ignoring other aspects. Eye movements are anatomically and functionally related to mechanisms of visual attention. Saccadic dysfunction might confound selective visual attention in PD. Methods: We studied visual selective attention in 22 medicated PD patients (clinical ON status, mild to moderate disease severity) and 22 age matched controls. We looked for possible interferences through oculomotor deficits. Two tasks were compared: free viewing of photographs and time optimal visual search of a hidden target. Visual search times (VST), task related dynamics of saccades, and hand-reaction and hand-movement times were analyzed. Results: In the free viewing task mild to moderately affected PD patients did not differ statistically from healthy subjects with respect to saccade dynamics. However, patients differed significantly from healthy subjects in the time optimal visual search task with 25% lower rates of successful searches. Hand movement reaction time did not differ in both groups, whereas hand movement execution time was significantly prolonged in PD patients. Conclusion: Saccadic oculomotor control and hand movement reaction times were intact, whereas in our less severely affected treated PD patients, visual selective attention was not. The highly reduced successful search rate might be related to disturbed programming and delayed execution of saccades during time optimal visual search due to decreased execution of serial-order sequential generation of saccades.

Post-stroke fatigue: a problem of altered corticomotor control?

ObjectivesWe recently showed that diminished motor cortical excitability is associated with high levels of post-stroke fatigue. Motor cortex excitability impacts movement parameters such as reaction and movement times. We predicted...

The Effect of Varying Target Sizes and Spaces between Target and Non-target Elements on Goal-directed Hand Movement Times while Driving

Abstract Expressed by Fitts in 1954, there is an inverse relationship between movement time and target size and/or the distance between the participant and a target; smaller and further away targets require longer movement times than larger, closer targets. Here, the applicability of Fitts’ law to an in-vehicle, dual-task setting is under investigation. In the current experiment, different target sizes and spaces between target and non-target elements (target-element space), were investigated in simulated driving and non-driving scenarios in two age groups (18 – 35 and 45 – 65 years old). The aim of this experiment was to investigate whether target size and target-element space (i.e., the space between targets and non-targets) would have an effect on the mean movement times of younger and older participants for driving and non-driving conditions. Participants pointed to and touched targets on a smartphone touch screen in a vehicle mock-up. Movement times were recorded while concurrently performing a simulated driving task (dual-task condition) and while performing just the pointing task (single task condition). Errors were defined and are presented. Mean movement times in the dual-task condition were significantly faster than in the single task condition. Additionally, in line with Fitts’ law, in-vehicle movement time decreased as a function of target size. Elements that had the most target-element space were moved to most quickly, however, the medium and small spaces did not differ. Differences between the two age groups were not found.

Eye-hand coordination during visuomotor adaptation with different rotation angles.

This study examined adaptive changes of eye-hand coordination during a visuomotor rotation task. Young adults made aiming movements to targets on a horizontal plane, while looking at the rotated feedback (cursor) of hand movements on a monitor. To vary the task difficulty, three rotation angles (30°, 75°, and 150°) were tested in three groups. All groups shortened hand movement time and trajectory length with practice. However, control strategies used were different among groups. The 30° group used proportionately more implicit adjustments of hand movements than other groups. The 75° group used more on-line feedback control, whereas the 150° group used explicit strategic adjustments. Regarding eye-hand coordination, timing of gaze shift to the target was gradually changed with practice from the late to early phase of hand movements in all groups, indicating an emerging gaze-anchoring behavior. Gaze locations prior to the gaze anchoring were also modified with practice from the cursor vicinity to an area between the starting position and the target. Reflecting various task difficulties, these changes occurred fastest in the 30° group, followed by the 75° group. The 150° group persisted in gazing at the cursor vicinity. These results suggest that the function of gaze control during visuomotor adaptation changes from a reactive control for exploring the relation between cursor and hand movements to a predictive control for guiding the hand to the task goal. That gaze-anchoring behavior emerged in all groups despite various control strategies indicates a generality of this adaptive pattern for eye-hand coordination in goal-directed actions.

P037: Characteristics of the Abbreviated Mental Test Score (AMTS) and Montreal Cognitive Assessment (MoCA) in consecutive older acute medicine patients

movements, on a touch screen while their eye movements were monitored using an eye tracking system. Based on performance parameters as describing timing and execution of eye and hand movements, patients were divided into a ‘fast’ and a ‘slow’ group. Measures of ADL and IADL interference, assessed using standardized scales, were compared between groups. Results: Dementia patients in the ‘slow’ group reported more frequently IADL interference in the categories reaching destinations beyond walking distance, shopping, meal preparing and work around the house. No differences between groups were found in frequencies of reported ADL interference. Conclusions: The results indicate that impairments found in a planning based eye–hand coordination task may be related to the degree of (I)ADL interference in dementia patients. This might suggest a prognostic role of eye–hand coordination in predicting future disability in dementia patients.

Both age and physical activity level impact on eye-hand coordination

Aging impacts on our ability to perform goal-directed aiming movements. Older adults generally make slower and shorter initial impulses towards the end target, and therefore require more time for corrections in the final movement stage. Recent studies however suggest that a physically active lifestyle may attenuate these age-related changes. Also, it remains unclear whether eye-movement control exhibits a similar pattern of adaptation in older adults. Therefore, the first aim of this study was to describe how age and physical activity level impact eye-hand coordination during discrete manual aiming. Young and older participants were divided into physically active and sedentary subgroups, and performed discrete aiming movements while hand and eye movements were recorded. Secondly, to determine whether older adults depend more on vision during aiming, the task was repeated without visual feedback. The results revealed that the typical age-related hand movement adaptations were not only observed in older, but also in sedentary young participants. Older and sedentary young participants also spent more hand movement time after the eyes fixated the end target. This finding does not necessarily reflect an augmented reliance on vision, as all groups showed similar aiming errors when visual feedback was removed. In conclusion, both age and physical activity level clearly impacted eye-hand coordination during discrete manual aiming. This adapted coordination pattern seems to be caused by other factors than an increased reliance on vision.

Quiet eye training improves surgical knot tying more than traditional technical training: a randomized controlled study

We examined the effectiveness of technical training (TT) and quiet eye training (QE) on the performance of one-handed square knot tying in surgical residents. Twenty surgical residents were randomly assigned to the 2 groups and completed pretest, training, retention, and transfer tests. Participants wore a mobile eye tracker that simultaneously recorded their gaze and hand movements. Dependent variables were knot tying performance (%), QE duration (%), number of fixations, total movement time (s), and hand movement phase time (s). The QE training group had significantly higher performance scores, a longer QE duration, fewer fixations, faster total knot tying times, and faster movement phase times compared with the TT group. The QE group maintained performance in the transfer test, whereas the TT group significantly decreased performance from retention to transfer. QE training significantly improved learning, retention, and transfer of surgical knot tying compared with a traditional technical approach. Both performance effectiveness (performance outcome) and movement efficiency (hand movement times) were improved using QE modeling, instruction, and feedback.