Performance limitations from delay in human and mechanical motor control

Beamish, Dan; Bhatti, Shabana; Wu, Jianhong; Jing, Zhujun

doi:10.1007/s00422-008-0235-z

Cited by 13 publications

(21 citation statements)

References 41 publications

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“…The widths and distances were informed by pre-trials. The range of IDs found by these matched those of MacKenzie & Ware, and those estimated by Beamish et al [4], [10]. The IDs were calculated using MacKenzie's method [32].…”

Section: Designsupporting

confidence: 67%

“…It should be noted that the model described above does not take into account visual feedback -or indeed any external delays. That is, even considering a system based only on proprioceptive cues the authors demonstrate a hard upper limit on performance [10].…”

Section: Models Of the Motor Systemmentioning

confidence: 95%

“…There is evidence ( [12], [10]) that the motor control system consists of multiple complex elements, some acting in parallel, and that the effects of latency on these is not equivalent. Thus in our experiment, aside from a Fitts's law-style task, we introduce a second task based on the Steering law.…”

Section: The Steering Lawmentioning

confidence: 99%

“…The human motor system has been modelled as a control loop, with inherent delays that place natural limitations on performance; movement cannot be coordinated on time-scales smaller than the inherent delay [10]. We therefore hypothesize that there may be a non-zero external latency which has no perceptible effect on the sensorimotor loop.…”

Section: Introductionmentioning

confidence: 99%

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The Effects of Low Latency on Pointing and Steering Tasks

Friston

Karlstrm

Steed

2016

IEEE Trans. Visual. Comput. Graphics

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Abstract-Latency is detrimental to interactive systems, especially pseudo-physical systems that emulate real-world behaviour. It prevents users from making quick corrections to their movement, and causes their experience to deviate from their expectations. Latency is a result of the processing and transport delays inherent in current computer systems. As such, while a number of studies have hypothesized that any latency will have a degrading effect, few have been able to test this for latencies less than ∼50 ms. In this study we investigate the effects of latency on pointing and steering tasks. We design an apparatus with a latency lower than typical interactive systems, using it to perform interaction tasks based on Fitts's law and the Steering law. We find evidence that latency begins to affect performance at ∼16 ms, and that the effect is non-linear. Further, we find latency does not affect the various components of an aiming motion equally. We propose a three stage characterisation of pointing movements with each stage affected independently by latency. We suggest that understanding how users execute movement is essential for studying latency at low levels, as high level metrics such as total movement time may be misleading.

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Section: Designsupporting

confidence: 67%

Section: Models Of the Motor Systemmentioning

confidence: 95%

Section: The Steering Lawmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Effects of Low Latency on Pointing and Steering Tasks

Friston

Karlstrm

Steed

2016

IEEE Trans. Visual. Comput. Graphics

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“…An additional property of the VITE circuit is that there exists a maximum performance possible when delay is present (Beamish et al 2008). This is strictly a delay effect and is a completely different behavior from the classical Fitts' law as a regression model where slope and Y-intercept may take arbitrary values.…”

Section: Introductionmentioning

confidence: 99%

Estimation of psychomotor delay from the Fitts’ law coefficients

et al. 2009

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An intrinsic property of human motor behavior is a trade-off between speed and accuracy. This is classically described by Fitts' law, a model derived by assuming that the human body has a limited capacity to transmit information in organizing motor behavior. However, Fitts' law can also be realized as an emergent property of movements generated by delayed feedback. In this article, we describe the relationship between the Fitts' law coefficients and the physiological parameters of the underlying delayed feedback circuit: the relaxation rate or time constant, and the psychomotor delay of the feedback process. This relationship is then used to estimate the motor circuit delay of several tasks for which Fitts' law data are available in the literature. We consistently estimate the delay to be between 0 and 112 ms. A further consequence of this model is that not all combinations of slope and Y-intercept in Fitts' law are possible when movements are generated by delayed feedback. In fact, it is only possible for an observed speed-accuracy trade-off to be generated by delayed feedback if the Fitts' law coefficients satisfy -0.482 < or = a/b < or = 3.343 [bits] where b represents the slope in bits per second and a represents the Y-intercept in seconds. If we assume human movement is generated by delayed feedback, then the Fitts' law coefficients should always be restricted to this range of values.

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Stability and robustness analysis for human pointing motions with acceleration under feedback delays

Varnell

Malisoff

Zhang

2016

Int. J. Robust. Nonlinear Control

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Pointer acceleration is often used in computer mice and other interfaces to increase the range and speed of pointing motions without sacrificing precision during slow movements. However, the effects of pointer acceleration are not yet well understood. We use a system perspective and feedback control to analyze the effects of pointer acceleration. We use a new pointer acceleration model connected in feedback with the vector integration to endpoint model for pointing motions. When there are no feedback delays, we prove global asymptotic stability of the closed loop system for a general class of acceleration profiles. We also prove robustness under delays and perturbations by building Lyapunov-Krasovskii functionals for delay systems, and we find state performance bounds using robust forward invariance with maximal perturbation sets. The results are relevant to designing pointing interfaces, and our simulations illustrate the good performance of our control under realistic operating conditions.In this work, we use a systems perspective to approach the problem of analyzing the effects of pointer acceleration. We build a dynamic model of human pointing motion with pointing acceleration, and we analyze its performance and stability properties. Our results provide insights into the impact of pointer acceleration in pointer interfaces, and have the potential to benefit future designs of such interfaces.Human pointing interfaces have been studied extensively in human-computer interaction, neuroscience, physiology, and psychology; see [5]. Two key results are the Fitts Law, which was was first presented in [6] and explains an invariant in pointing performance for many human pointing interfaces and tasks, and the vector integration to endpoint (or VITE) model, which was first presented in [7] and reproduces the Fitts Law by describing pointing motions. Other papers have analyzed the dynamics of human pointing as described by the VITE model; see [8][9][10][11][12], with some having feedback delays and some not having delays. Our work [13] used dissipativity to design and study pointing systems, and it gave a preliminary analysis of the VITE model in the dissipativity framework using a switching controller. Our conference article [14] presented the new model of pointer acceleration that is used in this paper and analyzed its stability and performance properties when connected in feedback to the VITE model without any feedback delays or perturbations or robust forward invariance.Our approach is novel because, to the best of our knowledge, we are the first to use a systems perspective to study pointer acceleration. We use a new model that captures most existing implementations of pointer acceleration, and we show that when the VITE dynamics are connected in feedback to the pointer acceleration model, the interconnection is globally asymptotically stable, including in cases with feedback delays. We include a robustness analysis under perturbations, which can arise from discretization errors and inaccuracies in human perception a...

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Performance limitations from delay in human and mechanical motor control

Cited by 13 publications

References 41 publications

The Effects of Low Latency on Pointing and Steering Tasks

The Effects of Low Latency on Pointing and Steering Tasks

Estimation of psychomotor delay from the Fitts’ law coefficients

Stability and robustness analysis for human pointing motions with acceleration under feedback delays

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