{"title":"Human movement strategies in uncertain environments: A synergy-based approach to the stability-agility tradeoff","authors":"Anvesh Naik , Ruchika Iqbal , Sébastien Hélie , Satyajit Ambike","doi":"10.1016/j.humov.2024.103259","DOIUrl":null,"url":null,"abstract":"<div><p>Humans frequently prepare for agile movements by decreasing stability. This facilitates transitions between movements but increases vulnerability to external disruptions. Therefore, humans might weigh the risk of disruption against the gain in agility and scale their stability to the likelihood of having to perform an agility-demanding action. We used the theory of motor synergies to investigate how humans manage this stability-agility tradeoff under uncertainty. This theory has long quantified stability using the synergy index, and reduction in stability before movement transitions using anticipatory synergy adjustment (ASA). However, the impact of uncertainty - whether a quick action should be executed or inhibited - on ASA is unknown. Furthermore, the impact of ASA on execution and inhibition of the action is unclear.</p><p>We combined multi-finger, isometric force production with the go/no-go paradigm. Thirty participants performed constant force (no-go task), rapid force pulse (go task), and randomized go and no-go trials (go/no-go task) in response to visual cues. We measured the pre-cue finger forces and computed ASA using the uncontrolled manifold method and quantified the spatio-temporal features of the force after the visual cue. We expected ASA in both go/no-go and go tasks, but larger ASA for the latter.</p><p>Surprisingly, we observed ASA only for the go task. For the go/no-go task, 53% of participants <em>increased</em> stability before the cue. The high stability hindered performance, leading to increased errors in no-go trials and lower peak forces in go trials. These results align with the stability-agility tradeoff. It is puzzling why some participants increased stability even though 80% of the trials demanded agility. This study indicates that individual differences in the effect of task uncertainty and motor inhibition on ASA is unexplored in motor synergy theory and presents a method for further development.</p></div>","PeriodicalId":55046,"journal":{"name":"Human Movement Science","volume":"97 ","pages":"Article 103259"},"PeriodicalIF":1.6000,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Human Movement Science","FirstCategoryId":"102","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0167945724000824","RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"NEUROSCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Humans frequently prepare for agile movements by decreasing stability. This facilitates transitions between movements but increases vulnerability to external disruptions. Therefore, humans might weigh the risk of disruption against the gain in agility and scale their stability to the likelihood of having to perform an agility-demanding action. We used the theory of motor synergies to investigate how humans manage this stability-agility tradeoff under uncertainty. This theory has long quantified stability using the synergy index, and reduction in stability before movement transitions using anticipatory synergy adjustment (ASA). However, the impact of uncertainty - whether a quick action should be executed or inhibited - on ASA is unknown. Furthermore, the impact of ASA on execution and inhibition of the action is unclear.
We combined multi-finger, isometric force production with the go/no-go paradigm. Thirty participants performed constant force (no-go task), rapid force pulse (go task), and randomized go and no-go trials (go/no-go task) in response to visual cues. We measured the pre-cue finger forces and computed ASA using the uncontrolled manifold method and quantified the spatio-temporal features of the force after the visual cue. We expected ASA in both go/no-go and go tasks, but larger ASA for the latter.
Surprisingly, we observed ASA only for the go task. For the go/no-go task, 53% of participants increased stability before the cue. The high stability hindered performance, leading to increased errors in no-go trials and lower peak forces in go trials. These results align with the stability-agility tradeoff. It is puzzling why some participants increased stability even though 80% of the trials demanded agility. This study indicates that individual differences in the effect of task uncertainty and motor inhibition on ASA is unexplored in motor synergy theory and presents a method for further development.
期刊介绍：
Human Movement Science provides a medium for publishing disciplinary and multidisciplinary studies on human movement. It brings together psychological, biomechanical and neurophysiological research on the control, organization and learning of human movement, including the perceptual support of movement. The overarching goal of the journal is to publish articles that help advance theoretical understanding of the control and organization of human movement, as well as changes therein as a function of development, learning and rehabilitation. The nature of the research reported may vary from fundamental theoretical or empirical studies to more applied studies in the fields of, for example, sport, dance and rehabilitation with the proviso that all studies have a distinct theoretical bearing. Also, reviews and meta-studies advancing the understanding of human movement are welcome.
These aims and scope imply that purely descriptive studies are not acceptable, while methodological articles are only acceptable if the methodology in question opens up new vistas in understanding the control and organization of human movement. The same holds for articles on exercise physiology, which in general are not supported, unless they speak to the control and organization of human movement. In general, it is required that the theoretical message of articles published in Human Movement Science is, to a certain extent, innovative and not dismissible as just "more of the same."
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