The role of eye movements in motor sequence learning

Visual behavior of racing bike cyclists in multi-tasking situations

Distracted biking can have serious repercussions for the rider such as accidents. The purpose of the present experiment was to determine the effect of visually monitoring two parameters, the cadence, and the heart rate on a bike computer fixed on a racing bike, and simultaneously detect hazardous traffic situations. Individuals (n = 20) were instructed to ride a racing bike that was fitted onto a roller trainer. After conducting a bicycle step test to assess the maximal heart rate (HFmax), participants were assigned to a within subject-design on a separate day. They were instructed to perform the riding task in two single-task conditions (only watching the traffic at the video with occluded or without occluded bike computer), two multi-tasking conditions (monitoring the cadence of 70 RPM or 90 RPM, monitoring the heart rate, and observing the traffic) and one control condition (no instructions). Percentage dwell time of the eye movements, the constant error from the target cadence, keeping the heart rate in an interval of 50% - 70% of the HFmax, and percentage of the recognized hazard traffic situations were analyzed. The analysis indicated that monitoring the parameters on the bike computer induced no significant decline in perceived hazardous traffic situations.

Visual behavior and road traffic hazard situations when using a bike computer on a racing bike: An eye movement study

Bike computers are an important equipment, especially on race bikes where athletes can monitor output parameters. The purpose of the present experiment was to determine the effect of visually monitoring the cadence of a bike computer and to perceive hazard traffic situations in a virtual environment. In a within subject-design individuals (N = 21) were instructed to perform the riding task in two single-task conditions (only watching the traffic at the video with occluded or without occluded bike computer), two dual-task conditions (monitoring the cadence of 70 RPM or 90 RPM and observing the traffic) and one control condition (no instructions). Percentage dwell time of the eye movements, the constant error from the target cadence, and percentage of the recognized hazard traffic situations were analyzed. The analysis indicated that the visual behavior to monitor the traffic was not reduced when individuals used a bike computer to control the cadence.

Don't watch your step: gaze behavior adapts with practice of a target stepping task

Vision plays a vital role in locomotor learning, providing feedback information to correct movement errors, and feedforward information to inform learned movement plans. Gaze behavior, or the distribution of fixation locations, can quantify how visual information is used during the motor learning process. How gaze behavior adapts during motor learning and in response to changing motor performance is poorly understood. This study examines if and how an individual's gaze behavior adapts during a sequence learning, target stepping task. We monitored the gaze behavior of 12 healthy young adults while they walked on a treadmill and attempted to precisely step on moving targets that were separated by variable distances (80%, 100%, and 120% of preferred step length). Participants completed a total of 11 trial blocks of 102 steps each. We hypothesized that both mean fixation distance would increase (participants would look farther ahead), and step error would decrease with experience. Following practice, participants significantly increased their fixation distance (P < 0.001) by 0.27 ± 0.18 steps and decreased their step error (P < 0.001) by 4.0 ± 1.7 cm, supporting our hypothesis. Our results suggest that early in the learning process, participants gaze behavior emphasized gathering visual information necessary for feedback motor control. As motor performance improved with experience, participants shifted their gaze fixation farther ahead placing greater emphasis on the visual information used for feedforward motor control. These findings provide important information about how gaze behavior changes in parallel with improvements in walking performance.NEW & NOTEWORTHY People consistently vary how they use visual information to inform walking. However, what drives this variation and how sampled visual information changes with locomotor learning is not well understood. Here, we find that gaze fixation locations moved farther ahead while step error decreases as participants practice a target stepping task. The results suggest that participants increasingly used a feedforward locomotor control strategy with practice.

Delay of gaze fixation during reaching movement with the non-dominant hand to a distant target

The present study examined the effects of hand and task difficulty on eye-hand coordination related to gaze fixation behavior (i.e., fixating a gaze to the target until reach completion) in single reaching movements. Twenty right-handed young adults made reaches on a digitizer, while looking at a visual target and feedback of hand movements on a computer monitor. Task difficulty was altered by having three target distances. In a small portion of trials, visual feedback was randomly removed at the target presentation. The effect of a moderate amount of practice was also examined using a randomized trial schedule across target-distance and visual-feedback conditions in each hand. The results showed that the gaze distances covered during the early reaching phase were reduced, and the gaze fixation to the target was delayed when reaches were performed with the left hand and when the target distance increased. These results suggest that when the use of the non-dominant hand or an increased task difficulty reduces the predictability of hand movements and its sensory consequences, eye-hand coordination is modified to enhance visual monitoring of the reach progress prior to gaze fixation. The randomized practice facilitated this process. Nevertheless, variability of reach trajectory was more increased without visual feedback for right-hand reaches, indicating that control of the dominant arm integrates more visual feedback information during reaches. These results together suggest that the earlier gaze fixation and greater integration of visual feedback during right-hand reaches contribute to the faster and more accurate performance in the final reaching phase.

Movement Sequence Learning: Cognitive Processing Demands to Develop a Response Structure

An experiment was designed to investigate the impact of a dual-task on the response structure of a 16-element movement sequence. The primary task was to move a lever to targets sequentially presented horizontally on the screen by elbow extension/flexion movements. The secondary task was a simple reaction time task triggered by moving the lever through targets at the middle and the end of the sequence. Participants were permitted to acquire the movement sequence on one day, and to perform the sequence on a second day under single-task and dual-task conditions. The results of the acquisition phase indicated that participants increased their performance over practice. Day 2 analysis indicated that performance of the repeated sequence was not deteriorated by the dual-task. This finding indicated that the response structure of the movement sequence performance was stable with regard to the secondary task. The current results are partially consistent with the theoretical assumption of an abstract representation for movement sequence execution.

Functional Use of Eye Movements for an Acting System

Movements of the eyes assist vision and support hand and body movements in a cooperative way. Despite their strong functional coupling, different types of movements are usually studied independently. We integrate knowledge from behavioral, neurophysiological, and clinical studies on how eye movements are coordinated with goal-directed hand movements and how they facilitate motor learning. Understanding the coordinated control of eye and hand movements can provide important insights into brain functions that are essential for performing or learning daily tasks in health and disease. This knowledge can also inform applications such as robotic manipulation and clinical rehabilitation.

The function of "looking-at-nothing" for sequential sensorimotor tasks: Eye movements to remembered action-target locations

When performing manual actions, eye movements precede hand movements to target locations: Before we grasp an object, we look at it. Eye-hand guidance is even preserved when visual targets are unavailable, e.g., grasping behind an occlusion. This "looking-atnothing" behavior might be functional, e.g., as "deictic pointer" for manual control or as memory-retrieval cue, or a by-product of automatization. Here, it is studied if looking at empty locations before acting on them is beneficial for sensorimotor performance. In five experiments, participants completed a click sequence on eight visual targets for 0-100 trials while they had either to fixate on the screen center or could move their eyes freely. During 50-100 consecutive trials, participants clicked the same sequence on a blank screen with free or fixed gaze. During both phases, participants looked at target locations when gaze shifts were allowed. With visual targets, target fixations led to faster, more precise clicking, fewer errors, and sparser cursor-paths than central fixation. Without visual information, a tiny free-gaze benefit could sometimes be observed and was rather a memory than a motor-calculation benefit. Interestingly, central fixation during learning forced early explicit encoding causing a strong benefit for acting on remembered targets later, independent of whether eyes moved then.

The influence of eye-movements on the development of a movement sequence representation during observational and physical practice

An experiment was conducted to examine the development of a movement sequence representation and the role of eye-movements during observational and physical practice. The task was to reproduce a 1300ms spatial-temporal pattern of a sequence of elbow flexions and extensions. An inter-manual transfer design with a retention and two effector transfer tests (contralateral limb) was used. The mirror transfer test required the same pattern of homologous muscle activation and a sequence of joint angles as experienced during the acquisition phase, and the non-mirror transfer test required the same visual-spatial pattern as performed or observed during acquisition. Participants were randomly assigned to one of four groups differing in eye-movements (free to use their eyes vs. instruction to fixate) and the practice type (observational practice vs. physical practice). The results indicated that permitting to use eye-movements facilitates sequence learning. This advantage was found on both practice types. The results of the transfer tests indicated that participants of the physical practice group who were permitted to use their eyes demonstrated superior transfer performance in the mirror transfer test, while participants in the observational practice group demonstrated better performance on the non-mirror transfer test. These findings indicated that eye-movements enhanced the development of a visual-spatial representation during observational practice as well as a motor representation during physical practice.

Effects of model types in observational learning on implicit sequential learning

This study investigated whether implicit learning of sequence by observation occurred in a serial reaction time task and whether the learning effects were modulated by model behavioral type. In Experiment 1, we let 20 participants perform a sequence for 12 blocks and chose the best and worst performance models based on reaction time and errors. In Experiment 2, new observers viewed a movie clip chosen from the following three: the best model performing the sequential task in the first (the first six blocks) or second session (the last six blocks), or the worst model performing the task in the first session. Then, the observers performed the observed sequence, a test sequence and awareness test. We found that (1) implicit sequential learning occurred by observation regardless of model behavior type, (2) the learning effects were not susceptible to model behavior type and (3) speed index reflecting reaction time became larger even in the test session when the observers viewed the best model performing the second session. Overall, observers developed general motor representations through action-observation. In addition, their responses were also contagious; if the model performed the sequence faster, the observer might be able to perform the sequence faster.

Magnifying visual target information and the role of eye movements in motor sequence learning

An experiment investigated the influence of eye movements on learning a simple motor sequence task when the visual display was magnified. The task was to reproduce a 1300 ms spatial-temporal pattern of elbow flexions and extensions. The spatial-temporal pattern was displayed in front of the participants. Participants were randomly assigned to four groups differing on eye movements (free to use their eyes/instructed to fixate) and the visual display (small/magnified). All participants had to perform a pre-test, an acquisition phase, a delayed retention test, and a transfer test. The results indicated that participants in each practice condition increased their performance during acquisition. The participants who were permitted to use their eyes in the magnified visual display outperformed those who were instructed to fixate on the magnified visual display. When a small visual display was used, the instruction to fixate induced no performance decrements compared to participants who were permitted to use their eyes during acquisition. The findings demonstrated that a spatial-temporal pattern can be learned without eye movements, but being permitting to use eye movements facilitates the response production when the visual angle is increased.