How one breaks Fitts’s Law and gets away with it: Moving further and faster involves more efficient online control

Glazebrook, Cheryl M.; Kiernan, Dovin; Welsh, Timothy N.; Tremblay, Luc

doi:10.1016/j.humov.2014.11.005

Cited by 14 publications

(18 citation statements)

References 28 publications

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“…This portion primarily relies on external sources of afferent information and is constrained by a feedback processing time-lag (Elliott et al, 2010;Meyer, Abrams, Kornblum, Wright and Smith, 1988). To date, the research assessing the early and late phases of movements to the farthest target indicate that the violation of Fitts' Law does not manifest in the time spent in the initial impulse, but instead, manifests in the time spent toward the end of the movement (Blinch, Cameron, Hodges and Chua, 2012;Glazebrook, Kiernan, Welsh and Tremblay, 2015). These data implicate online control processes in the violation of Fitts' Law.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the finding that the violation of Fitts' Law emerges in the late stages of the movement, Glazebrook et al (2015) suggested that the shorter than predicted MTs to the lastplaced target emerged because the initial response was planned to undershoot the last-placed target followed by a correction to the movement via a secondary acceleration (i.e., negativeto-positive acceleration zero-crossing). Indeed, the secondary acceleration may provide the 6 essential drive to the limb to reach the target sooner than usual.…”

Section: Introductionmentioning

confidence: 99%

“…Of interest, the recent suggestion of a violation coinciding with an optimized movement approach designed to prevent the cost of a potential error (Glazebrook et al, 2015) goes beyond the possibility of a perceptual antecedent (Adam et al, 2006; and potentially explains the influence of placeholders directly on motor processes (Bradi, Adam, Fischer and Pratt, 2009;Radulescu, Al-Aidroos, Adam, Fischer and Pratt, 2011). Previous accounts of the violation have brokered the contribution of planning and control processes to the violation of Fitts' Law using at least some assessments of the kinematics (e.g., Blinch et al, 2012;Glazebrook et al, 2015). To date, however, no 8 studies have directly examined the potential role of movement optimization and the associated nature of submovement kinematics (i.e., reversal/secondary acceleration/discontinuities).…”

Section: Introductionmentioning

confidence: 99%

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The violation of Fitts’ Law: an examination of displacement biases and corrective submovements

et al. 2016

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Fitts' Law holds that, to maintain accuracy, movement times of aiming movements must change as a result of varying degrees of movement difficulty. Recent evidence has emerged that aiming to a target located last in an array of placeholders results in a shorter movement time than would be expected by the Fitts' equation-a violation of Fitts' Law. It has been suggested that the violation emerges because the performer adopts an optimized movement strategy in which they partially pre-plan an action to the closest placeholder (undershoot the last placeholder) and rely on a secondary acceleration to propel the limb toward the last location when it is selected as the target (Glazebrook et al. in Hum Mov Sci 39:163-176, 2015). In the current study, we examine this proposal and further elucidate the processes underlying the violation by examining limb displacement and corrective submovements that occur when performers aim to different target locations. For our Main Study, participants executed discrete aiming movements in a five-placeholder array. We also reanalyzed data from a previously reported study in which participants aimed in placeholder and no-placeholder conditions (Blinch et al. in Exp Brain Res 223:505-515, 2012). The results showed the violation of Fitts' Law unfolded following peak velocity (online control). Further, the analysis showed that movements to the last target tended to overshoot and had a higher proportion of secondary submovements featuring a reversal than other categories of submovement (secondary accelerations, discontinuities). These findings indicate that the violation of Fitts' Law may, in fact, result from a strategic bias toward planning farther initial displacements of the limb which accommodates a shorter time in online control.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The violation of Fitts’ Law: an examination of displacement biases and corrective submovements

et al. 2016

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“…This difference may account for the relative effectiveness of our inverted formulation of Fitts' Law. However, other previous studies have reported violations of Fitts' Law (Adam et al, 2006; Glazebrook et al, 2015). Glazebrook et al (2015) determined that these Fitts' Law violations are the result of pre-planning of movements.…”

Section: Discussionmentioning

confidence: 80%

“…However, other previous studies have reported violations of Fitts' Law (Adam et al, 2006; Glazebrook et al, 2015). Glazebrook et al (2015) determined that these Fitts' Law violations are the result of pre-planning of movements. This explanation is also certainly plausible in the context of a cyclical task such as hammering.…”

Section: Discussionmentioning

confidence: 80%

Hammering Does Not Fit Fitts' Law

Petrič

Simpson

Ude

et al. 2017

Front. Comput. Neurosci.

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While movement is essential to human wellbeing, we are still unable to reproduce the deftness and robustness of human movement in automatons or completely restore function to individuals with many types of motor impairment. To better understand how the human nervous system plans and controls movements, neuromechanists employ simple tasks such as upper extremity reaches and isometric force tasks. However, these simple tasks rarely consider impacts and may not capture aspects of motor control that arise from real-world complexity. Here we compared existing models of motor control with the results of a periodic targeted impact task extended from Bernstein's seminal work: hammering a nail into wood. We recorded impact forces and kinematics from 10 subjects hammering at different frequencies and with hammers with different physical properties (mass and face area). We found few statistical differences in most measures between different types of hammer, demonstrating human robustness to minor changes in dynamics. Because human motor control is thought to obey optimality principles, we also developed a feedforward optimal simulation with a neuromechanically inspired cost function that reproduces the experimental data. However, Fitts' Law, which relates movement time to distance traveled and target size, did not match our experimental data. We therefore propose a new model in which the distance moved is a logarithmic function of the time to move that yields better results (R2 ≥ 0.99 compared to R2 ≥ 0.88). These results support the argument that humans control movement in an optimal way, but suggest that Fitts' Law may not generalize to periodic impact tasks.

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Current Theoretical Developments and Applications of Fitts’ Law: A Literature Review

Jiang

2019

Advances in Ergonomics in Design

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How one breaks Fitts’s Law and gets away with it: Moving further and faster involves more efficient online control

Cited by 14 publications

References 28 publications

The violation of Fitts’ Law: an examination of displacement biases and corrective submovements

The violation of Fitts’ Law: an examination of displacement biases and corrective submovements

Hammering Does Not Fit Fitts' Law

Current Theoretical Developments and Applications of Fitts’ Law: A Literature Review

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