scholarly journals Intermittent visual information and the multiple time scales of visual motor control of continuous isometric force production

2005 ◽  
Vol 67 (2) ◽  
pp. 335-344 ◽  
Author(s):  
Jacob J. Sosnoff ◽  
Karl M. Newell
2003 ◽  
Vol 03 (01) ◽  
pp. L23-L29 ◽  
Author(s):  
GOTTFRIED MAYER-KRESS ◽  
KATHERINE M. DEUTSCH ◽  
KARL M. NEWELL

In human movement, the large number of system degrees of freedom at different levels of analysis of the system, joints, muscles, motor units, cells etc, naturally affords complexity and adaptability in action. It also leads to variability in movement and its outcome, even in intentional efforts to reproduce the same movement or action goal. An example is continuous isometric force output to a constant force level where the amount and structure of force variability changes with information available, force level and individual differences. In this paper we model the control of isometric force production with piece-wise linear stochastic maps of multiple time scales. At the core of our model is a piecewise linear function, depending on three parameters that can be estimated from the observed data that is perturbed by additive Gaussian noise at a given level. The result of the stochastic forcing is that outside of a threshold interval the system behaves like a discrete Ornstein-Uhlenbeck process and inside it performs a Brownian motion. The model is shown to simulate the basic findings of the structure of human force variability that decreasing variability is correlated with increased dynamical complexity as measured with the "Approximate Entropy (ApEn)" statistic.


2018 ◽  
Author(s):  
Yan Liang ◽  
◽  
Daniele J. Cherniak ◽  
Chenguang Sun

2019 ◽  
Vol 11 (4) ◽  
pp. 1163 ◽  
Author(s):  
Melissa Bedinger ◽  
Lindsay Beevers ◽  
Lila Collet ◽  
Annie Visser

Climate change is a product of the Anthropocene, and the human–nature system in which we live. Effective climate change adaptation requires that we acknowledge this complexity. Theoretical literature on sustainability transitions has highlighted this and called for deeper acknowledgment of systems complexity in our research practices. Are we heeding these calls for ‘systems’ research? We used hydrohazards (floods and droughts) as an example research area to explore this question. We first distilled existing challenges for complex human–nature systems into six central concepts: Uncertainty, multiple spatial scales, multiple time scales, multimethod approaches, human–nature dimensions, and interactions. We then performed a systematic assessment of 737 articles to examine patterns in what methods are used and how these cover the complexity concepts. In general, results showed that many papers do not reference any of the complexity concepts, and no existing approach addresses all six. We used the detailed results to guide advancement from theoretical calls for action to specific next steps. Future research priorities include the development of methods for consideration of multiple hazards; for the study of interactions, particularly in linking the short- to medium-term time scales; to reduce data-intensivity; and to better integrate bottom–up and top–down approaches in a way that connects local context with higher-level decision-making. Overall this paper serves to build a shared conceptualisation of human–nature system complexity, map current practice, and navigate a complexity-smart trajectory for future research.


2021 ◽  
Vol 40 (9) ◽  
pp. 2139-2154
Author(s):  
Caroline E. Weibull ◽  
Paul C. Lambert ◽  
Sandra Eloranta ◽  
Therese M. L. Andersson ◽  
Paul W. Dickman ◽  
...  

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