2,245 research outputs found
Target Acquisition in Multiscale Electronic Worlds
Since the advent of graphical user interfaces, electronic information has grown exponentially, whereas the size of screen displays has stayed almost the same. Multiscale interfaces were designed to address this mismatch, allowing users to adjust the scale at which they interact with information objects. Although the technology has progressed quickly, the theory has lagged behind. Multiscale interfaces pose a stimulating theoretical challenge, reformulating the classic target-acquisition problem from the physical world into an infinitely rescalable electronic world. We address this challenge by extending Fittsâ original pointing paradigm: we introduce the scale variable, thus defining a multiscale pointing paradigm. This article reports on our theoretical and empirical results. We show that target-acquisition performance in a zooming interface must obey Fittsâ law, and more specifically, that target-acquisition time must be proportional to the index of difficulty. Moreover, we complement Fittsâ law by accounting for the effect of view size on pointing performance, showing that performance bandwidth is proportional to view size, up to a ceiling effect. The first empirical study shows that Fittsâ law does apply to a zoomable interface for indices of difficulty up to and beyond 30 bits, whereas classical Fittsâ law studies have been confined in the 2-10 bit range. The second study demonstrates a strong interaction between view size and task difficulty for multiscale pointing, and shows a surprisingly low ceiling. We conclude with implications of these findings for the design of multiscale user interfaces
A Control Model: Interpretation of Fitts' Law
The analytical results for several models are given: a first order model where it is assumed that the hand velocity can be directly controlled, and a second order model where it is assumed that the hand acceleration can be directly controlled. Two different types of control-laws are investigated. One is linear function of the hand error and error rate; the other is the time-optimal control law. Results show that the first and second order models with the linear control-law produce a movement time (MT) function with the exact form of the Fitts' Law. The control-law interpretation implies that the effect of target width on MT must be a result of the vertical motion which elevates the hand from the starting point and drops it on the target at the target edge. The time optimal control law did not produce a movement-time formula simular to Fitt's Law
HUMAN CONTROL OF ROBOTIC MECHANISMS: MODELLING AND ASSESSMENT OF ASSISTIVE DEVICES
The prescription and use of Assistive Technology, particularly teleprostheses,
may be enhanced by the use of standard assessment techniques. For input
devices, in particular, existing assessment studies, most of which are based
on Fitts' Law, have produced contradictory results. This thesis has made
contributions to these and related fields, particularly in the following four
areas.
Fitts' Law (and background information theory) is examined. The inability of
this paradigm to match experimental results is noted and explained.
Following a review of the contributing fields, a new method of assessing input
devices is proposed, based on Fitts' Law, classical control and the concept of
'profiling'.
To determine the suitability of the proposed method, it is applied to the results
of over 2000 trials. The resulting analysis emphasises the importance of interaction
effects and their influence on general comparison techniques for input
devices.
The process of verification has highlighted gain susceptability as a performance
criterion which reflects user susceptability; a technique which may be
particularly applicable to Assistive Technology.Dept. of Mechanical and Marine Engineerin
Assessment of Fitts' Law for Quantifying Combined Rotational and Translational Movements
Objective: To develop a model for human performance in combined translational and rotational movements based on Fitts' law. Background: Fitts' law has been successfully applied to translational movements in the past, providing generalization beyond a specific task as well as performance predictions. For movements involving both translations and rotations, no equivalent theory exists, making comparisons of input devices for these movements more ambiguous. Method: The study consisted of three experiments. In the first two, participants performed either pure translational or pure rotational movements of 1 degree of freedom. The third experiment involved the same movements combined. Results: On average, the performance times for combined movements were equal to the sum of the times for equivalent separate rotational and translational movements. A simple Fitts' law equivalent for combined movements with a similar slope as the separate components was proposed. In addition, a significant degree of coordination of the combined movements was found. This had a strong bias toward a parallel execution in 12 out of 13 participants. Conclusion: Combined movements with rotations and translations of 1 degree of freedom can be approximated using a simple Fitts' law equivalent. The rotational and translational components appear to be coordinated by the central nervous system to generate a parallel execution. Application: The results may help drive human interface designs and provide insights into the coordination of combined movements. Future extensions may be possible for the movements of higher degrees of freedom used in robot teleoperation and virtual reality applications.This work was supported by the Institute for Dexterous Space Robotics (Grant No. NNX06AD23G).Publicad
The Challenges in Modeling Human Performance in 3D Space with Fittsâ Law
With the rapid growth in virtual reality technologies, object interaction is
becoming increasingly more immersive, elucidating human perception and leading
to promising directions towards evaluating human performance under different
settings. This spike in technological growth exponentially increased the need
for a human performance metric in 3D space. Fitts' law is perhaps the most
widely used human prediction model in HCI history attempting to capture human
movement in lower dimensions. Despite the collective effort towards deriving an
advanced extension of a 3D human performance model based on Fitts' law, a
standardized metric is still missing. Moreover, most of the extensions to date
assume or limit their findings to certain settings, effectively disregarding
important variables that are fundamental to 3D object interaction. In this
review, we investigate and analyze the most prominent extensions of Fitts' law
and compare their characteristics pinpointing to potentially important aspects
for deriving a higher-dimensional performance model. Lastly, we mention the
complexities, frontiers as well as potential challenges that may lay ahead.Comment: Accepted at ACM CHI 2021 Conference on Human Factors in Computing
Systems (CHI '21 Extended Abstracts
Effects of feedback, mobility and index of difficulty on deictic spatial audio target acquisition in the horizontal plane
We present the results of an empirical study investigating the effect of feedback, mobility and index of difficulty on a deictic spatial audio target acquisition task in the horizontal plane in front of a user. With audio feedback, spatial audio display elements are found to enable usable deictic interac-tion that can be described using Fitts law. Feedback does not affect perceived workload or preferred walking speed compared to interaction without feedback. Mobility is found to degrade interaction speed and accuracy by 20%. Participants were able to perform deictic spatial audio target acquisition when mobile while walking at 73% of their pre-ferred walking speed. The proposed feedback design is ex-amined in detail and the effects of variable target widths are quantified. Deictic interaction with a spatial audio display is found to be a feasible solution for future interface designs
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