Fitts's Law Research Articles

Evaluating cervical spine mobility and Fitt's law compliance: The DidRen laser test adapted for virtual reality with age and sex effects

Cervical spine mobility assessment is crucial in rehabilitation to monitor patient progress. This study introduces the DidRen VR test, a virtual reality (VR) adaptation of the conventional DidRen laser test, aimed at evaluating cervical spine mobility.We conducted a cross-sectional study involving fifty healthy participants that underwent the DidRen VR test. The satisfaction of Fitts' law within this VR adaptation was examined and we analyzed the effects of age and sex on the sensorimotor performance metrics.Our findings confirm that Fitts' law is satisfied, demonstrating a predictable relationship between movement time and the index of difficulty, which suggest that the DidRen VR test can simulate real-world conditions. A clear influence of age and sex on performance was observed, highlighting significant differences in movement efficiency and accuracy across demographics, which may necessitate personalized assessment strategies in clinical rehabilitation practices.The DidRen VR test presents an effective tool for assessing cervical spine mobility, validated by Fitts' law. It offers a viable alternative to real-world method, providing precise control over test conditions and enhanced engagement for participants. Since age and sex significantly affect sensorimotor performance, personalized assessments are essential. Further research is recommended to explore the applicability of the DidRen VR test in clinical settings and among patients with neck pain.

Fitts Law as a Restrained Random Walk

Fitts Law as a Restrained Random Walk

Temporal properties of the speed-accuracy trade-off for arm-pointing movements in various directions around the body.

Human body movements are based on the intrinsic trade-off between speed and accuracy. Fitts's law (1954) shows that the time required for movement is represented by a simple logarithmic equation and is applicable to a variety of movements. However, few studies have determined the role of the direction in modulating the performance of upper limb movements and the effects of the interactions between direction and distance and between direction and target size. This study examined the variations in temporal properties of the speed-accuracy trade-off in arm-pointing movements that directly manipulate objects according to the direction, distance, and target size. Participants performed pointing movements to the targets with 3 different sizes presented at 15 locations (5 directions and 3 distances) on a horizontal plane. Movement time (MT) for each trial in each condition was obtained. Subsequently, Mackenzie's model (1992), MT = a + b log2(D/W +1), where D and W represent the distance and width of the target, respectively, was fitted. The slope factor b, a fitted parameter in the equation, was calculated and evaluated according to the changes in the direction, distance, and target size. The results showed that MTs exhibited anisotropy in the hemifield, being the smallest in the right-forward direction. Additionally, the slope factor b, as a function of distance, was smaller in the rightward direction than in the forward and left-forward directions. These results suggest that the degree of difficulty of upper limb movements expands heterogeneously in various directions around the body.

The Impact of Limited Previous Motor Experience on Action Possibility Judgments in People with Spinal Muscle Atrophy.

Previous studies have shown that people with limited motor capabilities may rely on previous motor experience when making action possibility judgments for others. In the present study, we examined if having limited previous motor experience, as a consequence of spinal muscle atrophy (SMA), alters action possibility judgments. Participants with SMA and neurologically healthy (NH) sex- and age-matched controls performed a perceptual-motor judgment task using the Fitts's law paradigm. Participants observed apparent motion videos of reciprocal aiming movements with varying levels of difficulty. For each movement, participants predicted the shortest movement time (MT) at which a neurologically healthy young adult could accurately perform the task. Participants with SMA predicted significantly longer MTs compared to controls; however, the predicted MTs of both SMA and NH participants exhibited a Fitts's law relationship (i.e., the predicted MTs significantly increased as movement difficulty increased). Overall, these results provide evidence that participants with SMA who have limited, or no motor experience may make more conservative action possibility judgments for others. Critically, our finding that the pattern of action possibility judgments was not different between SMA and NH groups suggests that limited previous motor experience may not completely impair action possibility judgments.

환자 중심 의료서비스를 위한 2차 병원 이비인후과 초진 진료 사전문진표 UX/UI 개선에 관한 연구

In order to improve the satisfaction of patients and doctors in terms of patient-centered medical services, the results of this study approached from the perspective of medical examination and conducted research and analysis of literature, case studies, and hospital visits. It was designed intuitively by applying the questionnaire, which is the basis, as a responsive box according to the Fitts Law, focusing on readability to fit the mobile screen with symptoms and items for each part. Second, an environment in which in-depth medical interviews can be created was created by reducing questioning time by providing a space for users to describe questions that may be missed in a short medical treatment time. Third, the pre-diagnosis questionnaire prepared for first visit suggested the possibility of in-depth medical care by reducing closed conversations between patients and doctors and reducing unnecessary questioning time with open-ended questions. Fourth, the mobile access to the pre-first visit medical questionnaire resulted in technical limitations in applying the integrated hospital system. The significance of this study is to propose a design for improving patient-doctor communication and treatment satisfaction during limited treatment hours. We expect a medical environment that can increase the satisfaction of patients and doctors in terms of patient-centered medical services and the use of basic data that can be provided in a mobile environment for the preparation of patient questionnaires necessary for first visits and outpatients.

Assessment of human expertise and movement kinematics in first-person shooter games.

In contrast to traditional professional sports, there are few standardized metrics in professional esports (competitive multiplayer video games) for assessing a player's skill and ability. We assessed the performance of professional-level players in Aim LabTM, a first-person shooter training and assessment game, with two target-shooting tasks. These tasks differed primarily in target size: the task with large targets provided an incentive to be fast but imprecise and the task with large targets provided an incentive to be precise but slow. Each player's motor acuity was measured by characterizing the speed-accuracy trade-off in shot behavior: shot time (elapsed time for a player to shoot at a target) and shot spatial error (distance from center of a target). We also characterized the fine-grained kinematics of players' mouse movements. Our findings demonstrate that: 1) movement kinematics depended on task demands; 2) individual differences in motor acuity were significantly correlated with kinematics; and 3) performance, combined across the two target sizes, was poorly characterized by Fitts Law. Our approach to measuring motor acuity has widespread applications not only in esports assessment and training, but also in basic (motor psychophysics) and clinical (gamified rehabilitation) research.

Action-Specific Perception & Performance on a Fitts's Law Task in Virtual Reality: The Role of Haptic Feedback

While user's perception and performance are predominantly examined independently in virtual reality, the Action-Specific Perception (ASP) theory postulates that the performance of an individual on a task modulates this individual's spatial and time perception pertinent to the task's components and procedures. This paper examines the association between performance and perception and the potential effects that tactile feedback modalities could generate. This paper reports a user study (N=24), in which participants performed a standardized Fitts's law target acquisition task by using three feedback modalities: visual, visuo-electrotactile, and visuo-vibrotactile. The users completed 3 Target Sizes × 2 Distances × 3 feedback modalities = 18 trials. The size perception, distance perception, and (movement) time perception were assessed at the end of each trial. Performance-wise, the results showed that electrotactile feedback facilitates a significantly better accuracy compared to vibrotactile and visual feedback, while vibrotactile provided the worst accuracy. Electrotactile and visual feedback enabled a comparable reaction time, while the vibrotactile offered a substantially slower reaction time than visual feedback. Although amongst feedback types the pattern of differences in perceptual aspects were comparable to performance differences, none of them was statistically significant. However, performance indeed modulated perception. Significant action-specific effects on spatial and time perception were detected. Changes in accuracy modulate both size perception and time perception, while changes in movement speed modulate distance perception. Also, the index of difficulty was found to modulate all three perceptual aspects. However, individual differences appear to affect the magnitude of action-specific effects. These outcomes highlighted the importance of haptic feedback on performance, and importantly the significance of action-specific effects on spatial and time perception in VR, which should be considered in future VR studies.

Development of Tests for Arm Coordination Impairment in Paralympic Classification.

BackgroundIn Paralympic sport, classification of impairment with the ability to detect misrepresentation of abilities is mandatory. In wheelchair rugby, there is currently no objective method to classify arm coordination impairment. In previous research, sufficient correlation between the spiral test (ST) and activity in wheelchair rugby was found in athletes with coordination impairment. However, the ST depends on maximum voluntary effort.PurposeTo assess if the ST is an objective test for arm coordination impairment, in which maximum voluntary effort can be distinguished from intentional misrepresentation. The aims of this study were to (1) assess the test-retest reliability of the ST and (2) assess if Fitts's law is applicable to the ST.MethodsNineteen volunteers without impairments performed two sessions with three STs per arm. The STs were projected and measured on a tablet and had three different indices of difficulty based on differences in spiral width. The time to complete the spiral was measured and a penalty time was added for each time the borderline of the spiral was touched (3 s) or crossed (5 s).ResultsTest-retest reliability was assessed using a Bland-Altman analysis and showed limits of agreement that were wider than the margins of 2SD from the group mean. Repeated measurement correlation coefficients between the index of difficulty according to Fitts's law and the movement time were > 0.95 (p-value < 0.001) for both test and retest. A post-hoc optimisation of penalty times revealed an optimum penalty time of 2.0 s for the dominant arm and 2.5 for the non-dominant arm for any contact with the margins of the spiral.ConclusionsThe ST has sufficient test-retest reliability and Fitts's law is applicable. Therefore, it is a promising option for classification of arm coordination impairment with the option to distinguish intentional misrepresentation from maximum voluntary effort.

The Speed–Accuracy Tradeoff as a Subject of Psychological Analysis

The present research featured the regularities, according to which the accuracy of human movements is associated with the length of these movements and time. The author considered the speed–accuracy tradeoff problem by analyzing the procedural aspect of cognitive performance. The experiment included more than a thousand participants and was performed on a portable touch screen device that tested the subject's attitude to solving problems in terms of speed or accuracy. The research objective was to identify significantly different ways of solving the speed–accuracy tradeoff dilemma. At the fine motor level, the participants failed to accomplish a one-to-one correspondence between target area and target time. This ambiguity was a manifestation of various cognitive strategies for performing a speed–accuracy tradeoff task. The Fitts law violations were determined using a wide range of statistical methods and manifested themselves at the level of criteria analysis for the normality of data distribution, types of variance analysis, and multivariate data analysis. The cluster analysis could register various strategies for performing the speed–accuracy tradeoff task. Additional variables, e.g. professional status of the subjects, made it possible to interpret the differences according to specific skills in solving cognitive tasks and to clarify the nature of these skills.

Конструирование признаков индивидуальных различий в задаче «Компромисс скорость-точность» методом периодограммы

The research is devoted to finding the attributes that would allow detailing the factors breaking Fitts's law. Fitts's law ties together the distance to a target area with the accuracy and movement time. Frequency analysis of two time rows that depict, respectively, the accuracy and time needed to solve the task, is used. To analyze the results we used the periodogram method. It allows us to evaluate how the period of time, given to a person under test, appears in his solutions of the task. The features of periodicity suppression are interpreted as specific characteristics of people under test. The research deals with the data received from 1023 test takers, each of those solved 120 tasks. It is not only the fact of interrupting the given periodicity revealed in the results, but also a set of typical cases of such interruption is demonstrated from the points of view of two traditionally used variables - accuracy and time - and a new, third, variable, that is the accurate and fast solution mindset. This mindset is given as a special kind of instruction during the test. As a result, the authors revealed that Fitts's law manifestation on the level of periods that subordinate distance changes is distinctive for the majority of test takers. However, the character of periodicity changes easily. For example, it was found out that about a half of examinees demonstrate the periodicity consisting of 30 tasks, this periodicity appears stable both from the points of speed and accuracy, and on the level of dependent variables. At the same time, the periodicity of 10 tasks depends a lot on the speed. A small amount of results characterized by the local absence of periodicity was also found. The authors remark successful application of the attribute construction method, it allows us to describe in detail the character of individual differences manifestation, being short and compact in giving new descriptive attributes at the same time. The ways of improving and perfecting the methods of interactive spatial choice task solving are planned in the long view.

Effect of target distance on controllability for myocontrol

Abstract Myocontrol holds great promise because it has the potential to provide flexible and accurate prosthetic control that approaches the quality of normal movement. Speed and accuracy are important factors to consider when applying myoelectric signals to external devices. Fitts's law can be used to assess the speed-accuracy trade-off. We hypothesized that speed is affected not only by accuracy as prescribed by Fitts's law, but also by target distances independent of target size. A total of 12 healthy adult subjects were studied. Subjects controlled the vertical movement of a computer cursor by contracting their dominant first dorsal interosseus muscle to reach targets as quickly as possible. We manipulated twenty-five different target distances in order to obtain five indices of difficulty, as defined by Fitts's law, combined with five target widths. We tested the relationship between movement time and the index of difficulty as predicted by Fitts's law among different combinations of target distance and widths. Results showed a significant linear regression for all conditions, with the exception of a significantly longer movement time than predicted for targets close to the start point. Movements to these targets showed significantly higher relative variance during stabilization, higher overshoot, and lower success. Therefore, we found that with comparable index of difficulty, small distance movements had a higher variability, slower movement, and higher rates of error compared to larger distance movements. Our results are consistent with our hypothesis that low muscle activation required for short distances results in higher variability and low controllability in reaching the target as required by the task demand. Neurophysiological mechanisms underlying the violation of the Fitts's law relationship are discussed. These results have significance for myocontrol applications, and we suggest that such applications require control signals with sufficient recruitment to reduce variability at lower levels of muscle activation.

On Motor Performance in Virtual 3D Object Manipulation.

Fitts's law facilitates approximate comparisons of target acquisition performance across a variety of settings. Conceptually, also the index of difficulty of 3D object manipulation with six degrees of freedom can be computed, which allows the comparison of results from different studies. Prior experiments, however, often revealed much worse performance than one would reasonably expect on this basis. We argue that this discrepancy stems from confounding variables and show how Fitts's law and related research methods can be applied to isolate and identify relevant factors of motor performance in 3D manipulation tasks. The results of a formal user study ( n=21) demonstrate competitive performance in compliance with Fitts's model and provide empirical evidence that simultaneous 3D rotation and translation can be beneficial.

Enhancing Physical Human Evasion of Moving Threats Using Tactile Cues.

New human-centric approaches to safety can combine over-head camera views with situational awareness tools to enable humans to avoid rapidly evolving threats such as moving machines or falling debris. This article explores how 360° information can be used to inform humans of potential collisions. Specifically, we quantify how different individual (tactile, audio, and visual) and combined cue modalities affect failure rates and reaction times. Human-subject experiments were conducted in a custom virtual reality environment that simulates objects rapidly moving toward the subject. In order to successfully perform their task, the human subject must physically move their body out of the path of the moving threat before a collision occurs. This exploration of full body physical response differentiates this article from previous related studies. The results of the 18-subject study provide quantified data on a range of cues and cue combinations. The study quantified failure rates and reaction times as a function of index of difficulty (Fitt's Law) and threat directionality. The results confirm the hypothesis that the addition of tactile cues statistically improve performance compared to non-tactile cues with regards to failure rate and reaction time. This demonstrates how sensory cues can improve human physical response to rapid threats.

Modeling endpoint distribution of pointing selection tasks in virtual reality environments

Understanding the endpoint distribution of pointing selection tasks can reveal the underlying patterns on how users tend to acquire a target, which is one of the most essential and pervasive tasks in interactive systems. It could further aid designers to create new graphical user interfaces and interaction techniques that are optimized for accuracy, efficiency, and ease of use. Previous research has explored the modeling of endpoint distribution outside of virtual reality (VR) systems that have shown to be useful in predicting selection accuracy and guide the design of new interactive techniques. This work aims at developing an endpoint distribution of selection tasks for VR systems which has resulted in EDModel , a novel model that can be used to predict endpoint distribution of pointing selection tasks in VR environments. The development of EDModel is based on two users studies that have explored how factors such as target size, movement amplitude, and target depth affect the endpoint distribution. The model is built from the collected data and its generalizability is subsequently tested in complex scenarios with more relaxed conditions. Three applications of EDModel inspired by previous research are evaluated to show the broad applicability and usefulness of the model: correcting the bias in Fitts's law, predicting selection accuracy, and enhancing pointing selection techniques. Overall, EDModel can achieve high prediction accuracy and can be adapted to different types of applications in VR.

Evaluation of intuitive trunk and non-intuitive leg sEMG control interfaces as command input for a 2-D Fitts's law style task.

Duchenne muscular dystrophy (DMD) is a muscular condition that leads to muscle loss. Orthotic devices may present a solution for people with DMD to perform activities of daily living (ADL). One such device is the active trunk support but it needs a control interface to identify the user’s intention. Myoelectric control interfaces can be used to detect the user’s intention and consequently control an active trunk support. Current research on the control of orthotic devices that use surface electromyography (sEMG) signals as control inputs, focuses mainly on muscles that are directly linked to the movement being performed (intuitive control). However in some cases, it is hard to detect a proper sEMG signal (e.g., when there is significant amount of fat), which can result in poor control performance. A way to overcome this problem might be the introduction of other, non-intuitive forms of control. This paper presents an explorative study on the comparison and learning behavior of two different control interfaces, one using sEMG of trunk muscles (intuitive) and one using sEMG of leg muscles that can be potentially used for an active trunk support (non-intuitive). Six healthy subjects undertook a 2-D Fitts’s law style task. They were asked to steer a cursor into targets that were radially distributed symmetrically in five directions. The results show that the subjects were generally able to learn to control the tasks using either of the control interfaces and improve their performance over time. Comparison of both control interfaces demonstrated that the subjects were able to learn the leg control interface task faster than the trunk control interface task. Moreover, the performance on the diagonal-targets was significantly lower compared to the one directional-targets for both control interfaces. Overall, the results show that the subjects were able to control a non-intuitive control interface with high performance. Moreover, the results indicate that the non-intuitive control may be a viable solution for controlling an active trunk support.

A study of hand-movement gestures to substitute for mouse-cursor placement using an inertial sensor

Abstract. This paper examines the new study of hand orientation as a substitute for computer-mouse movement and is evaluated based on ISO/TS 9241 part 411: Ergonomics of human–system interaction-evaluation methods for the design of physical input devices. Two pairs of hand-orientation candidates were evaluated, using, for example, pitch–roll and pitch–yaw to substitute for up–down and left–right mouse-cursor movements. The up–down cursor movement was generated from the pitch orientation, while the left–right cursor movement was generated from the roll or yaw orientation, depending on the evaluation of the proposed gesture. The research employed a standard computer mouse as a baseline comparison for the study. The empirical study was conducted to evaluate quantitative performance such as throughput and movement time. The best impression resulted when the throughput had the greatest value as well as the shortest movement time. The performance test was based on Fitts's law using a multi-directional tapping test as suggested by ISO/TS 9241-411. The test was divided into several levels of difficulty, including high, medium, low, and very low. The other assessment is qualitative and was performed using the comfort-rating scale questionnaire and rating of perceived exertion of comfortability and fatigue. The quantitative results show that pitch–yaw throughput is slightly higher than for the pitch–roll gesture, and that the movement time in pitch–yaw is slightly less than in pitch–roll, although there is no statistically significant difference between the two. We also found that pitch–yaw movements have a higher level of comfort based on the comfort-rating scale test. Since the test was divided into levels of difficulty, we identified those gestures suitable for the task with a low and very low level of difficulty based on throughput, movement time, and error-rate results. Finally, this study suggests that pitch–roll and pitch–yaw movements of the hand can be used as substitutes for the mouse, and that pitch–yaw movements are superior in regard to causing less fatigue than pitch–roll movements. Furthermore, this study provides a new suggestion for a suitable level of difficulty when using an inertial sensor as an emulator for the movement of a mouse cursor in the field of human–computer interaction.

SPEED-ACCURACY TRADEOFF OF INSTEP KICK IN YOUNG SOCCER PLAYERS

The speed-accuracy trade-off of fast movements acts inversely and as such is known as the Fitts's law. The aim of this study is to determine how instep kick (IK) speed grading instructions affect the instep kick speed and accuracy. The primary hypothesis assumes that a complex motor task such as IK has an inverse relation between speed and accuracy, and the secondary hypothesis assumes that the applied speed grading instructions are sensitive. The research involved 13 male players, the average age of 15 years (±1.6). The experimental protocol included the execution of IK at five different speeds, determined by verbal instructions to respondents. For assessment of kicking accuracy, we observed the following dependent variables: mean radial error (MRE), bivariate variable error (BVE), and centroid radial error (CRE). Comparative analysis has shown that higher accuracy (reduced MRE) and kicking consistency (reduced BVE) are achieved under lower kicking speeds, but these effects were not achieved in regard to CRE. Subsequent analyses have shown that MRE has a tendency towards a significant difference between the slowest and fastest kicks (p=0.068-0.075), while in the case of BVE it has been found that there are differences between the slowest and all other speed levels (p≤0.05). The main findings of this study have indicated a partial existence (two of three variables) of an inverse relationship between speed and accuracy in complex motor tasks such as IK (multi-joint and discrete motion).

Design analysis of distributed control system (DCS) room with curved monitor

This paper presents the design analysis of distributed control system room with curved monitor. The objective of this research is to seek the possibility of replacement current monitor using eye ergonomic and human factor analysis. The research are backed up with three theories of Fitts’s Law, Horopter Theory, and Westheimer’s Saccadic Eye Movement Model. Fitts Law used to illustrate the general powers and faults of humans and machines. Horopter used to match another distinctive of our visual ergonomic: the placement of surfaces of monitors. Saccadic eye movements used to describe the express movements of eyes with monitor shape. The survey was conducted to operators seeking possibility to use curved monitor to replace the flat monitor. The researcher used simulator for Boiling Water Reactor (BWR) and its training movies and asking the participant doing the experiment then filling up questionnaires. Participants will be selected from the panel DCS operator doing their job in oil, gas and petrochemical manufacturing plants. The questionnaires are analysed by Rasch Model Analysis, to seek the benefit of curved monitor than flat monitor. Rasch analysis to find internal test reliability and conclusion out the each item analysis on visual ergonomic and human factor interaction.

Evaluation of Control Interfaces for Active Trunk Support

A feasibility study was performed to evaluate the control interfaces for a novel trunk support assistive device (Trunk Drive), namely, joystick, force on sternum, force on feet, and electromyography (EMG) to be used by adult men with Duchene muscular dystrophy. The objective of this paper was to evaluate the performance of the different control interfaces during a discrete position tracking task. We built a one degree of freedom flexion-extension active trunk support device that was tested on 10 healthy men. An experiment, based on the Fitts law, was conducted, whereby subjects were asked to steer a cursor representing the angle of the Trunk Drive into a target that was shown on a graphical user interface, using the above-mentioned control interfaces. The users could operate the Trunk Drive via each of the control interfaces. In general, the joystick and force on sternum were the fastest in movement time (more than 40%) without any significant difference between them, but there was a significant difference between force on sternum on the one hand, and EMG and force on feet on the other. All control interfaces proved to be feasible solutions for controlling an active trunk support, each of which had specific advantages.

Object width modulates object-based attentional selection.

Visual input typically includes a myriad of objects, some of which are selected for further processing. While these objects vary in shape and size, most evidence supporting object-based guidance of attention is drawn from paradigms employing two identical objects. Importantly, object size is a readily perceived stimulus dimension, and whether it modulates the distribution of attention remains an open question. Across four experiments, the size of the objects in the display was manipulated in a modified version of the two-rectangle paradigm. In Experiment 1, two identical parallel rectangles of two sizes (thin or thick) were presented. Experiments 2-4 employed identical trapezoids (each having a thin and thick end), inverted in orientation. In the experiments, one end of an object was cued and participants performed either a T/L discrimination or a simple target-detection task. Combined results show that, in addition to the standard object-based attentional advantage, there was a further attentional benefit for processing information contained in the thick versus thin end of objects. Additionally, eye-tracking measures demonstrated increased saccade precision towards thick object ends, suggesting that Fitts's Law may play a role in object-based attentional shifts. Taken together, these results suggest that object-based attentional selection is modulated by object width.