Speed–accuracy tradeoff in Fitts’ law tasks—on the equivalency of actual and nominal pointing precision

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.

Download Full-text

Accuracy Characteristics of Throwing as a Result of Maximum Force Effort

Perceptual and Motor Skills ◽

10.2466/pms.1998.86.3c.1211 ◽

1998 ◽

Vol 86 (3_suppl) ◽

pp. 1211-1217 ◽

Cited By ~ 42

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.

Download Full-text

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

eLife ◽

10.7554/elife.57021 ◽

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.

Download Full-text

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

Journal of Individual Differences ◽

10.1027/1614-0001/a000021 ◽

2010 ◽

Vol 31 (3) ◽

pp. 130-137 ◽

Cited By ~ 12

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.

Download Full-text

Linking Personality With Basic Cognition: Need for Closure vs. the Speed-Accuracy Tradeoff

PsycEXTRA Dataset ◽

10.1037/e528942014-512 ◽

2014 ◽

Author(s):

Babette Rae ◽

Scott Brown ◽

Maxim Bushmakin ◽

Mark Rubin

Keyword(s):

Need For Closure ◽

Speed Accuracy ◽

Basic Cognition ◽

Accuracy Tradeoff

Download Full-text

Speed/accuracy tradeoff in directed forgetting

PsycEXTRA Dataset ◽

10.1037/e536982012-049 ◽

1997 ◽

Author(s):

Jeffry S. Kellogg ◽

Xiangen Hu ◽

William Marks

Keyword(s):

Directed Forgetting ◽

Speed Accuracy ◽

Accuracy Tradeoff

Download Full-text

Faculty Opinions recommendation of One process is not enough! A speed-accuracy tradeoff study of recognition memory.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1022398.255622 ◽

2004 ◽

Author(s):

Andrew Yonelinas

Keyword(s):

Recognition Memory ◽

Speed Accuracy ◽

Accuracy Tradeoff

Download Full-text

Trading accuracy for speed over the course of a decision

Journal of Neurophysiology ◽

10.1152/jn.00038.2021 ◽

2021 ◽

Author(s):

Gerard Derosiere ◽

David Thura ◽

Paul Cisek ◽

Julie Duqué

Keyword(s):

Late Stage ◽

Human Subjects ◽

Sensory Information ◽

Decision Task ◽

Unique Extension ◽

Dynamic Changes ◽

Performance Accuracy ◽

Accuracy Criterion ◽

Speed Accuracy ◽

Accuracy Tradeoff

Humans and other animals often need to balance the desire to gather sensory information (to make the best choice) with the urgency to act, facing a speed-accuracy tradeoff (SAT). Given the ubiquity of SAT across species, extensive research has been devoted to understanding the computational mechanisms allowing its regulation at different timescales, including from one context to another, and from one decision to another. However, animals must frequently change their SAT on even shorter timescales - i.e., over the course of an ongoing decision - and little is known about the mechanisms that allow such rapid adaptations. The present study aimed at addressing this issue. Human subjects performed a decision task with changing evidence. In this task, subjects received rewards for correct answers but incurred penalties for mistakes. An increase or a decrease in penalty occurring halfway through the trial promoted rapid SAT shifts, favoring speeded decisions either in the early or in the late stage of the trial. Importantly, these shifts were associated with stage-specific adjustments in the accuracy criterion exploited for committing to a choice. Those subjects who decreased the most their accuracy criterion at a given decision stage exhibited the highest gain in speed, but also the highest cost in terms of performance accuracy at that time. Altogether, the current findings offer a unique extension of previous work, by suggesting that dynamic changes in accuracy criterion allow the regulation of the SAT within the timescale of a single decision.

Download Full-text