scholarly journals High-fidelity musculoskeletal modeling reveals that motor planning variability contributes to the speed-accuracy tradeoff

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Mazen Al Borno ◽  
Saurabh Vyas ◽  
Krishna V Shenoy ◽  
Scott L Delp
Keyword(s):  
Neural Activity ◽  
Three Dimensional ◽  
Motor Planning ◽  
Good Control ◽  
Population Level ◽  
Task Demands ◽  
Movement Speed ◽  
Fitts Law ◽  
Speed Accuracy ◽  
Accuracy Tradeoff

A long-standing challenge in motor neuroscience is to understand the relationship between movement speed and accuracy, known as the speed-accuracy tradeoff. Here, we introduce a biomechanically realistic computational model of three-dimensional upper extremity movements that reproduces well-known features of reaching movements. This model revealed that the speed-accuracy tradeoff, as described by Fitts’ law, emerges even without the presence of motor noise, which is commonly believed to underlie the speed-accuracy tradeoff. Next, we analyzed motor cortical neural activity from monkeys reaching to targets of different sizes. We found that the contribution of preparatory neural activity to movement duration (MD) variability is greater for smaller targets than larger targets, and that movements to smaller targets exhibit less variability in population-level preparatory activity, but greater MD variability. These results propose a new theory underlying the speed-accuracy tradeoff: Fitts’ law emerges from greater task demands constraining the optimization landscape in a fashion that reduces the number of ‘good’ control solutions (i.e., faster reaches). Thus, contrary to current beliefs, the speed-accuracy tradeoff could be a consequence of motor planning variability and not exclusively signal-dependent noise.

scholarly journals High-fidelity Musculoskeletal Modeling Reveals a Motor Planning Contribution to the Speed-Accuracy Tradeoff

2019 ◽  
Author(s):  
Mazen Al Borno ◽  
Saurabh Vyas ◽  
Krishna V. Shenoy ◽  
Scott L. Delp
Keyword(s):  
Optimal Control ◽  
Optimal Control Theory ◽  
Three Dimensional ◽  
Motor Planning ◽  
Reaching Movements ◽  
High Fidelity ◽  
Movement Duration ◽  
Fitts Law ◽  
Speed Accuracy ◽  
Accuracy Tradeoff

AbstractThe speed-accuracy tradeoff is a fundamental aspect of goal-directed motor behavior, empirically formalized by Fitts’ law, which relates movement duration to movement distance and target width. Here, we introduce a computational model of three-dimensional upper extremity movements that reproduces well-known features of reaching movements and is more biomechanically realistic than previous models. Critically, these features arise without the need of signal-dependent noise. We analyzed motor cortical neural activity from monkeys reaching to targets of different sizes. We found that the contribution of preparatory neural states to movement duration variability was greater for smaller targets than larger targets, and that movements to smaller targets exhibited less variability in preparatory neural states, but greater movement duration variability. Taken together, these results suggest that Fitts’ law emerges from greater task demands constraining the optimization landscape in a fashion that reduces the number of “good” control solutions (i.e., faster reaches). Thus, the speed-accuracy tradeoff could be a consequence of motor planning variability and optimal control theory, and not exclusively signal-dependent noise, as is currently held.Significance StatementA long-standing challenge in motor neuroscience is to understand the relationship between movement speed and accuracy, known as the speed-accuracy tradeoff. We introduce a computational model of reaching movements based on optimal control theory using a realistic model of musculoskeletal dynamics. The model synthesizes three-dimensional point-to-point reaching movements that reproduce kinematics features reported in motor control studies. Such high-fidelity modeling reveals that the speed-accuracy tradeoff as described by Fitts’ law emerges even without the presence of motor noise, which is commonly believed to underlie the speed-accuracy tradeoff. This suggests an alternative theory based on suboptimal control solutions. The crux of this theory is that some features of human movement are attributable to planning variability rather than execution noise.

scholarly journals Prolonged response time helps eliminate residual errors in visuomotor adaptation

2021 ◽  
Author(s):  
Lisa Langsdorf ◽  
Jana Maresch ◽  
Mathias Hegele ◽  
Samuel D. McDougle ◽  
Raphael Schween
Keyword(s):  
Cognitive Strategies ◽  
Motor Planning ◽  
Visuomotor Adaptation ◽  
Movement Planning ◽  
Planning Time ◽  
Full Compensation ◽  
Speed Accuracy ◽  
Residual Errors ◽  
Prolonged Response ◽  
Accuracy Tradeoff

AbstractOne persistent curiosity in visuomotor adaptation tasks is that participants often do not reach maximal performance. This incomplete asymptote has been explained as a consequence of obligatory computations within the implicit adaptation system, such as an equilibrium between learning and forgetting. A body of recent work has shown that in standard adaptation tasks, cognitive strategies operate alongside implicit learning. We reasoned that incomplete learning in adaptation tasks may primarily reflect a speed-accuracy tradeoff on time-consuming motor planning. Across three experiments, we find evidence supporting this hypothesis, showing that hastened motor planning may primarily lead to under-compensation. When an obligatory waiting period was administered before movement start, participants were able to fully counteract imposed perturbations (Experiment 1). Inserting the same delay between trials – rather than during movement planning – did not induce full compensation, suggesting that the motor planning interval influences the learning asymptote (Experiment 2). In the last experiment (Experiment 3), we asked participants to continuously report their movement intent. We show that emphasizing explicit re-aiming strategies (and concomitantly increasing planning time) also lead to complete asymptotic learning. Findings from all experiments support the hypothesis that incomplete adaptation is, in part, the result of an intrinsic speed-accuracy tradeoff, perhaps related to cognitive strategies that require parametric attentional reorienting from the visual target to the goal.

Accuracy Characteristics of Throwing as a Result of Maximum Force Effort

1998 ◽  
Vol 86 (3_suppl) ◽  
pp. 1211-1217 ◽  
Author(s):  
Bruce R. Etnyre
Keyword(s):  
The Other ◽  
Average Error ◽  
Maximal Level ◽  
Maximal Force ◽  
Fitts Law ◽  
Variable Error ◽  
Throwing Accuracy ◽  
Dart Throwing ◽  
Speed Accuracy ◽  
Accuracy Tradeoff

Fitts' law predicts the accuracy of movement to a target decreases as the velocity of the movement increases. This speed-accuracy tradeoff has been examined under numerous conditions. During some tasks, however, increased force to nearly maximal level decreases the variability of the movement (Sherwood & Schmidt, 1980). This condition apparently produced results different from what would be predicted by Fitts' law. The purpose of the present study was to examine the effects of maximal force on dart throwing accuracy and variability. 54 subjects were categorized into groups based upon their experience with dart throwing: Advanced, Intermediate, or Beginners. Each subject performed two sessions of 15 trials. Subjects were instructed to “throw normally” for one session and “throw as hard as you can” for the other session. Distances from the target (triple-20 area) on the regulation dart board were measured and recorded after each of three darts was thrown. Average Error and Variable Error were calculated for each condition for each subject. The Average Error and Variable Error were greatest for the Beginner group and least for the Advanced group. For all three experience categories both Average Error and Variable Error were significantly greater when subjects performed with maximal force. The greater average error for the maximal force for all subjects suggested the speed-accuracy tradeoff applied to this aiming task. The greater variability in accuracy with maximal force suggested a ceiling effect, which reduced variability in previous studies, was not achieved.

Individual Measures of Time Perception Predict Performance in a Timed Reaching Task

2017 ◽  
Vol 61 (1) ◽  
pp. 1380-1384
Author(s):  
Elliot Nauert ◽  
Douglas J. Gillan
Keyword(s):  
Time Perception ◽  
Movement Planning ◽  
Movement Speed ◽  
Spatial Accuracy ◽  
Reaching Task ◽  
Time Sensitivity ◽  
Movement Strategies ◽  
Speed Accuracy ◽  
Accuracy Tradeoff

In temporally-constrained reaching tasks, participants make rapid movements to a target while making their movements last a designated length of time. It has been well-established that effective target width, a measure of spatial accuracy, increases linearly with movement speed. This study sought to understand how individual differences in temporal sensitivity affect this speed-accuracy tradeoff. It was found that time sensitivity did not affect spatial components of the timed reaching task, but it was related to temporal components of the task. Ideas regarding the role of time perception in movement planning as well as differences in movement strategies for short and long target intervals are discussed.

scholarly journals A neural mechanism of speed-accuracy tradeoff in macaque area LIP

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Timothy Hanks ◽  
Roozbeh Kiani ◽  
Michael N Shadlen
Keyword(s):  
Neural Activity ◽  
Decision Process ◽  
Neural Mechanism ◽  
Threshold Level ◽  
Lateral Intraparietal Area ◽  
Neural Modulation ◽  
Gradual Accumulation ◽  
Speed Accuracy ◽  
Speed And Accuracy ◽  
Accuracy Tradeoff

Decision making often involves a tradeoff between speed and accuracy. Previous studies indicate that neural activity in the lateral intraparietal area (LIP) represents the gradual accumulation of evidence toward a threshold level, or evidence bound, which terminates the decision process. The level of this bound is hypothesized to mediate the speed-accuracy tradeoff. To test this, we recorded from LIP while monkeys performed a motion discrimination task in two speed-accuracy regimes. Surprisingly, the terminating threshold levels of neural activity were similar in both regimes. However, neurons recorded in the faster regime exhibited stronger evidence-independent activation from the beginning of decision formation, effectively reducing the evidence-dependent neural modulation needed for choice commitment. Our results suggest that control of speed vs accuracy may be exerted through changes in decision-related neural activity itself rather than through changes in the threshold applied to such neural activity to terminate a decision.

scholarly journals The speed-accuracy tradeoff reveals flexible access to accumulating sensory evidence during human decision making

2018 ◽  
Author(s):  
Stephanie Nelli ◽  
Sirawaj Itthipuripat ◽  
Nuttida Rungratsameetaweemana ◽  
John T. Serences
Keyword(s):  
Decision Making ◽  
Task Demands ◽  
Event Related Potential ◽  
Response Threshold ◽  
Evidence Accumulation ◽  
Human Decision ◽  
Sensory Evidence ◽  
Adaptively Adjusting ◽  
Speed Accuracy ◽  
Accuracy Tradeoff

AbstractDecisions made about identical perceptual stimuli can be radically different under changing task demands. For example, the need to make a fast decision undermines the accuracy of that decision, a well-documented effect termed the speed-accuracy tradeoff (SAT). Models of the SAT are generally based on theories of decision making in which responses are triggered only after sensory evidence accumulation terminates at a set threshold. Within this accumulate-to-bound framework, speed pressure operates by lowering the response threshold, allowing for faster responses at the expense of accumulated sensory evidence. To empirically examine the mechanisms necessary for adaptively adjusting the speed and accuracy of decisions, we used an event-related potential that indexes sensory evidence accumulation in the human brain. Instead of lowering response thresholds, we found that speed pressure adaptively shifts responses to occur close to where the rate of evidence accumulation peaks. Moreover, responses are not triggered automatically by the termination of the accumulation process, as sensory evidence continues to build after speeded decisions. Together these results suggest that response processes adaptively access accumulating sensory evidence depending on task demands and support parallel over serial models of decision making.

Neuroticism and Speed-Accuracy Tradeoff in Self-Paced Speeded Mental Addition and Comparison

2010 ◽  
Vol 31 (3) ◽  
pp. 130-137 ◽  
Author(s):  
Hagen C. Flehmig ◽  
Michael B. Steinborn ◽  
Karl Westhoff ◽  
Robert Langner
Keyword(s):  
Reaction Time ◽  
Response Speed ◽  
Time Variability ◽  
Reaction Time Variability ◽  
Comparison Task ◽  
Processing Efficiency ◽  
Mental Addition ◽  
Speed Accuracy ◽  
The Relationship ◽  
Accuracy Tradeoff

Previous research suggests a relationship between neuroticism (N) and the speed-accuracy tradeoff in speeded performance: High-N individuals were observed performing less efficiently than low-N individuals and compensatorily overemphasizing response speed at the expense of accuracy. This study examined N-related performance differences in the serial mental addition and comparison task (SMACT) in 99 individuals, comparing several performance measures (i.e., response speed, accuracy, and variability), retest reliability, and practice effects. N was negatively correlated with mean reaction time but positively correlated with error percentage, indicating that high-N individuals tended to be faster but less accurate in their performance than low-N individuals. The strengthening of the relationship after practice demonstrated the reliability of the findings. There was, however, no relationship between N and distractibility (assessed via measures of reaction time variability). Our main findings are in line with the processing efficiency theory, extending the relationship between N and working style to sustained self-paced speeded mental addition.

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