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How Common Is the Exponential Decay Pattern of Motor Skill Acquisition? A Brief Investigation

Geneviève N. Olivier, Christopher S. Walter, Serene S. Paul, Leland E. Dibble, and Sydney Y. Schaefer

Motor performance is classically described as improving nonlinearly with practice, demonstrating rapid improvements early in practice with stabilization later, which is commonly modeled by exponential decay functions. However, retrospective analyses of our previously collected data challenge this theoretical model of motor skill acquisition, suggesting that a majority of individual learners actually demonstrate patterns of motor improvement different from this classical model. A convenience sample of young adults, older adults, and people with Parkinson disease trained on the same functional upper-extremity task. When fitting three-parameter exponential decay functions to individual participant data, the authors found that only 13.3% of young adults, 40.9% of older adults, and 66.7% of adults with Parkinson disease demonstrated this “classical” skill acquisition pattern. Thus, the three-parameter exponential decay pattern may not well-represent individuals’ skill acquisition of complex motor tasks; instead, more individualized analysis methods may be warranted for advancing a theoretical understanding of motor skill acquisition.

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Restoring Walking Complexity in Older Adults Through Arm-in-Arm Walking: Were Almurad et al.’s (2018) Results an Artifact?

Samar Ezzina, Clément Roume, Simon Pla, Hubert Blain, and Didier Delignières

The analysis of stride series revealed a loss of complexity in older people, which correlated with the falling propensity. A recent experiment evidenced an increase of walking complexity in older participants when they walked in close synchrony with a younger companion. Moreover, a prolonged experience of such synchronized walking yielded a persistent restoration of complexity. This result, however, was obtained with a unique healthy partner, and it could be related to a particular partner’s behavior. The authors’ aim was to replicate this important finding using a different healthy partner and to compare the results to those previously obtained. The authors successfully replicated the previous results: synchronization yielded an attraction of participants’ complexity toward that of their partner and a restoration of complexity that persisted in two posttests, 2 and 6 weeks after the end of the training sessions. This study shows that this complexity restoration protocol can be applied successfully with another partner, and allows us to conclude that it can be generalized.

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Influence of Chronotype on Motor Behavior in Healthy Individuals: Analyses of Manual Dexterity in Different Times of the Day

Nathálya Gardênia de Holanda Marinho Nogueira, Bárbara de Paula Ferreira, Fernanda Veruska Narciso, Juliana Otoni Parma, Sara Edith Souza de Assis Leão, Guilherme Menezes Lage, and Lidiane Aparecida Fernandes

This study investigated the influence of chronotype on motor behavior in a manual dexterity task performed at different times of the day. Sixteen healthy adults of each chronotype (morning, evening, and neither), as measured by the Morningness–Eveningness Questionnaire, practiced both conditions of the Grooved Pegboard Test either in the morning or in the afternoon to early evening. The “neither” chronotype (65.12 ± 7.46) was outperformed (ps ≤ .03) by both the morning (56.09 ± 7.21) and evening (58.94 ± 7.53) chronotypes when the task had higher cognitive and motor demand but was not outperformed in the task with lower demand (morning = 18.46 ± 2.11; evening = 19.34 ± 2.79; neither = 21.47 ± 2.54; p > .05). No difference between the morning and evening chronotypes was found at the different times of the day (ps > .05), suggesting that a manual dexterity task is not sufficiently demanding to be influenced by chronotype.

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Differential Effects of Perturbation Magnitude on Reactive Balance Control in Young Sedentary Adults

Erika Zemková, Alena Cepková, and José M. Muyor

This study investigates postural responses to unexpected perturbations induced by a load release of different weights. Groups of 26 men (age 22.6 ± 2.4 years, height 178.0 ± 9.1 cm, and body mass 86.9 ± 11.5 kg) and 21 women (age 21.9 ± 2.7 years, height 168.8 ± 6.8 cm, and body mass 65.3 ± 8.7 kg) underwent load-triggered postural perturbations by 1 and 2 kg while standing on a force plate with either eyes open or eyes closed. Postural perturbations induced by a heavier load, representing about 2% and 3% of body weight in men and women, respectively, led to significantly higher peak anterior and peak posterior center of pressure displacements when compared with a lighter load (29.6% and 45.4%, respectively) both with eyes open (36.9%) and closed (42.1%). Their values were significantly lower in men than women only when a higher load was used (∼25%). However, there were no significant differences in time to peak anterior and posterior center of pressure displacements. These findings indicate that heavier load-induced postural perturbations are greater in women than men regardless of visual conditions. This underlines the importance of loading dose in the magnitude of postural responses to externally induced perturbations.

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Individuals With Intellectual Disabilities Rely on Somatosensory Information Rather Than Visual Information to Catch a Ball

W. Tolentino-Castro, L. Mochizuki, and H. Wagner

According to the literature, persons with intellectual disabilities have poor motor control in tasks in which motor anticipation is needed. Our study aimed to assess their motor behavior during interceptive tasks (a tennis ball interception with external-and-oneself throw conditions). A stick-bar was used as a reference or to support cloth to occlude a ball’s trajectory. Catch performance and interceptive behavior were analyzed (26 persons). The results show that high/low values of the initial approaching movement led to successful/successful catches, respectively. Our results are in line with the literature about the impact of poor motor control on performance in those with intellectual disabilities. We suggest that low anticipation may relate to problems in real-life situations.

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Unprompted Alteration of Freely Chosen Movement Rate During Stereotyped Rhythmic Movement: Examples and Review

Ernst Albin Hansen

Investigations of behavior and control of voluntary stereotyped rhythmic movement contribute to the enhancement of motor function and performance of disabled, sick, injured, healthy, and exercising humans. The present article presents examples of unprompted alteration of freely chosen movement rate during voluntary stereotyped rhythmic movements. The examples, in the form of both increases and decreases of movement rate, are taken from activities of cycling, finger tapping, and locomotion. It is described that, for example, strength training, changed power output, repeated bouts, and changed locomotion speed can elicit an unprompted alteration of freely chosen movement rate. The discussion of the examples is based on a tripartite interplay between descending drive, rhythm-generating spinal neural networks, and sensory feedback, as well as terminology from dynamic systems theory.

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Kinematics and Esthetics of Grand Battement After Static and Dynamic Hamstrings Stretching in Adolescents

Frédéric Dierick, Fabien Buisseret, Loreda Filiputti, and Nathalie Roussel

The objective of this study was to explore the effects of static and dynamic hamstring muscles stretching on kinematics and esthetics of grand battement (high velocity kicks) in adolescent recreational dancers. Sixteen participants were assessed before and immediately after both stretching modalities. Kinematics of movement was measured by an optoelectronic system and esthetics was scored by a jury of professional dancers. Both stretching modalities led to significant kinematic differences compared with without stretching. Significant linear correlations between kinematic parameters and esthetic scores have been observed: improving dancers’ physical performances has noticeable impact on the perception of their movements.

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Dissociating the Influence of Perceptual Biases and Contextual Artifacts Within Target Configurations During the Planning and Control of Visually Guided Action

James W. Roberts, Nicholas Gerber, Caroline J. Wakefield, and Philip J. Simmonds

The failure of perceptual illusions to elicit corresponding biases within movement supports the view of two visual pathways separately contributing to perception and action. However, several alternative findings may contest this overarching framework. The present study aimed to examine the influence of perceptual illusions within the planning and control of aiming. To achieve this, we manipulated and measured the planning/control phases by respectively perturbing the target illusion (relative size-contrast illusion; Ebbinghaus/Titchener circles) following movement onset and detecting the spatiotemporal characteristics of the movement trajectory. The perceptual bias that was indicated by the perceived target size estimates failed to correspondingly manifest within the effective target size. While movement time (specifically, time after peak velocity) was affected by the target configuration, this outcome was not consistent with the direction of the perceptual illusions. These findings advocate an influence of the surrounding contextual information (e.g., annuli) on movement control that is independent of the direction predicted by the illusion.

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Volume 25 (2021): Issue 2 (Apr 2021)

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Bernstein’s Philosophy of Time: An Unknown Manuscript by Nikolai Bernstein (1949)

Mark L. Latash and Vera L. Talis

The authors have presented an unpublished manuscript by Nikolai Aleksandrovich Bernstein written in the form of a diary in 1949. Bernstein focused on the concept of time as a coordinate in four-dimensional space and discussed a variety of issues, including the definition of time, its measurement, time travel, asymmetry of the past and future, and even linguistics. In particular, he offered a definition of life tightly linked to the concept of time. Overall, this manuscript offers a glimpse into Bernstein’s thinking, his sense of humor, and his sarcasm, intimately coupled with the very serious attitude to scientific discourse.