Differential effects of internal versus external focus of instruction on action planning and performance in patients with right and left hemispheric stroke

Kantak, Shailesh; Johnson, Tessa; William, Marsh

doi:10.1016/j.humov.2020.102654

Cited by 3 publications

(2 citation statements)

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“…Across a variety of motor activities (from balance and jumping to tennis and golf), instructions to focus on internal features such as how an individual's body is moving (e.g., arm postures during a tennis swing) tends to result in worse performance compared to instructions directing focus toward external features associated with how the environment is affected by the movement (e.g., the motion of the racket and ball) (for reviews, see [21][22][23][24][25]. Thus task instructions can have a surprisingly strong effect on the way in which people perform motor tasks, and suggest the importance of attending to body-independent motion trajectories when body position is not explicitly critical (for a similar effect in stroke patients, see [26]).…”

Section: Introductionmentioning

confidence: 99%

“…Based on our prior study (Wong 2019), we reasoned that it should be possible to use instructions to set this context. Indeed, across a variety of motor activities, task instructions have been shown to strongly modulate where individuals focus their attention during a task, consequently affecting task success (for reviews, see (Wulf, 2007; Wulf, 2013) (for a similar effect in stroke patients, see (Kantak et al, 2020)). In these studies, instructions to focus on internal features such as how an individual’s body is moving (e.g., arm postures during a tennis swing) interestingly tend to result in worse performance compared to instructions directing focus toward external features associated with how the environment is affected by the movement (e.g., the motion of the racket and ball).…”

Section: Introductionmentioning

confidence: 99%

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Action imitation via trajectory-based or posture-based planning

Barhorst-Cates

Isaacs

Buxbaum

et al. 2020

Preprint

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Movement imitation is a significant daily activity involved in social interaction and motor learning. Although imitation remains poorly understood, recent research suggests that it may be achieved in two distinct ways. In posture-based imitation, movements reproduce how the body should look and feel, and are sensitive to the relative positioning of body parts. In trajectory imitation, movements mimic the spatiotemporal motion path of the end effector. We hypothesized that people can imitate via either mechanism. If true, we would expect to see a switch cost when individuals change from one mechanism to the other. To test this, twenty-five healthy young adults performed a sequential multitasking imitation task. Participants were first instructed to pay attention to the limb postures or the hand path of a video-recorded model. They next performed an intervening motor task that was neutral, congruent, or incongruent with the instructed imitation type. Finally, participants imitated the modeled movement. Spatiotemporal imitation accuracy was greatest after a neutral intervening task, and worst after posture matching. When the primary task involved imitating trajectories, we observed a switch cost: movements following the posture-matching intervening task were less consistent with baseline (neutral) performance, suggesting performance was disrupted by the incongruence. Incongruent primary and intervening tasks also reduced cross-subject consistency. Such effects were not observed when imitating limb postures. In summary, we observed a partial dissociation between posture matching and trajectory imitation as a result of instructions and intervening tasks that is nevertheless consistent with the existence of two computationally distinct imitation mechanisms.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Action imitation via trajectory-based or posture-based planning

Barhorst-Cates

Isaacs

Buxbaum

et al. 2020

Preprint

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Implicit motor sequence learning using three-dimensional reaching movements with the non-dominant left arm

Smith,

Baird,

Buitendorp

et al. 2024

Exp Brain Res

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Interlimb differences in reach control could impact the learning of a motor sequence that requires whole-arm movements. The purpose of this study was to investigate the learning of an implicit, 3-dimensional whole-arm sequence task with the non-dominant left arm compared to the dominant right arm. Thirty-one right-hand dominant adults completed two consecutive days of practice of a motor sequence task presented in a virtual environment with either their dominant right or non-dominant left arm. Targets were presented one-at-a-time alternating between Random and Repeated sequences. Task performance was indicated by the time to complete the sequence (response time), and kinematic measures (hand path distance, peak velocity) were used to examine how movements changed over time. While the Left Arm group was slower than the Right Arm group at baseline, both groups significantly improved response time with practice with the Left Arm group demonstrating greater gains. The Left Arm group improved performance by decreasing hand path distance (straighter path to targets) while the Right Arm group improved performance through a smaller decrease in hand path distance combined with increasing peak velocity. Gains made during practice on Day 1 were retained on Day 2 for both groups. Overall, individuals reaching with the non-dominant left arm learned the whole-arm motor sequence task but did so through a different strategy than individuals reaching with the dominant right arm. The strategy adopted for the learning of movement sequences that require whole-arm movements may be impacted by differences in reach control between the nondominant and dominant arms.

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