Spatial and temporal characteristics of rapid cursor-positioning movements with electromechanical mice in human-computer interaction

Kinematic markers of skill in first-person shooter video games

Video games present a unique opportunity to study motor skill. First-person shooter (FPS) games have particular utility because they require visually guided hand movements that are similar to widely studied planar reaching tasks. However, there is a need to ensure the tasks are equivalent if FPS games are to yield their potential as a powerful scientific tool for investigating sensorimotor control. Specifically, research is needed to ensure that differences in visual feedback of a movement do not affect motor learning between the two contexts. In traditional tasks, a movement will translate a cursor across a static background, whereas FPS games use movements to pan and tilt the view of the environment. To this end, we designed an online experiment where participants used their mouse or trackpad to shoot targets in both visual contexts. Kinematic analysis showed player movements were nearly identical between contexts, with highly correlated spatial and temporal metrics. This similarity suggests a shared internal model based on comparing predicted and observed displacement vectors rather than primary sensory feedback. A second experiment, modeled on FPS-style aim-trainer games, found movements exhibited classic invariant features described within the sensorimotor literature. We found the spatial metrics tested were significant predictors of overall task performance. More broadly, these results show that FPS games offer a novel, engaging, and compelling environment to study sensorimotor skill, providing the same precise kinematic metrics as traditional planar reaching tasks.

Real-life Wrist Movement Patterns Capture Motor Impairment in Individuals with Ataxia-Telangiectasia

Sensitive motor outcome measures are needed to efficiently evaluate novel therapies for neurodegenerative diseases. Devices that can passively collect movement data in the home setting can provide continuous and ecologically valid measures of motor function. We tested the hypothesis that movement patterns extracted from continuous wrist accelerometer data capture motor impairment and disease progression in ataxia-telangiectasia. One week of continuous wrist accelerometer data were collected from 31 individuals with ataxia-telangiectasia and 27 controls aged 2-20 years old. Longitudinal wrist sensor data were collected in 14 ataxia-telangiectasia participants and 13 controls. A novel algorithm was developed to extract wrist submovements from the velocity time series. Wrist sensor features were compared with caregiver-reported motor function on the Caregiver Priorities and Child Health Index of Life with Disabilities survey and ataxia severity on the neurologist-performed Brief Ataxia Rating Scale. Submovements became smaller, slower, and less variable in ataxia-telangiectasia compared to controls. High-frequency oscillations in submovements were increased, and more variable and low-frequency oscillations were decreased and less variable in ataxia-telangiectasia. Wrist movement features correlated strongly with ataxia severity and caregiver-reported function, demonstrated high reliability, and showed significant progression over a 1-year interval. These results show that passive wrist sensor data produces interpretable and reliable measures that are sensitive to disease change, supporting their potential as ecologically valid motor biomarkers. The ability to obtain these measures from a low-cost sensor that is ubiquitous in smartwatches could help facilitate neurological care and participation in research regardless of geography and socioeconomic status.

Accuracy and Reliability of At-home Quantification of Motor Impairments Using a Computer-based Pointing Task with Children with Ataxia-Telangiectasia

Methods for obtaining accurate quantitative assessments of motor impairments are essential in accessibility research, design of adaptive ability-based assistive technologies, as well as in clinical care and medical research. Currently, such assessments are typically performed in controlled laboratory or clinical settings under professional supervision. Emerging approaches for collecting data in unsupervised settings have been shown to produce valid data when aggregated over large populations, but it is not yet established if in unsupervised settings measures of research or clinical significance can be collected accurately and reliably for individuals. We conducted a study with 13 children with ataxia-telangiectasia and 9 healthy children to analyze the validity, test-retest reliability, and acceptability of at-home use of a recent active digital phenotyping system, called Hevelius. Hevelius produces 32 measures derived from the movement trajectories of the mouse cursor, and it produces a quantitative estimate of motor impairment in the dominant arm using the dominant arm component of the Brief Ataxia Rating Scale (BARS). The severity score estimates generated by Hevelius from single at-home sessions deviated from clinician-assigned BARS scores more than the severity score estimates generated from single sessions conducted under researcher supervision. However, taking a median of as few as 2 consecutive sessions produced severity score estimates that were as accurate or better than the estimates produced from single supervised sessions. Further, aggregating as few as 2 consecutive sessions resulted in good test-retest reliability (ICC = 0.81 for A-T participants). This work demonstrated the feasibility of performing accurate and reliable quantitative assessments of individual motor impairments in the dominant arm through tasks performed at home without supervision by the researchers. Further work is needed, however, to assess how broadly these results generalize.

A one- and two-phased model of aimed movement with eye-hand incompatibility

Aimed movement is ubiquitous and has been extensively investigated. However, little research exists when the hand movements are incompatible with eye movements such as when viewing through a mirror or when performing laparoscopic surgery. An experiment was designed to investigate how individuals perform under one-dimensional and two-dimensional inversion with direct viewing as a reference condition. Twenty-four right-handed university students participated in this experiment and completed all aimed movements with a full-factorial design of movement amplitude at three levels and index of difficulty at 10-levels in three visual conditions of direct, viewing through a mirror (1D inversion) and observing through a right-angled mirror (2D inversion). Learning is rather rapid with direct viewing and with 1D inversion. However, participants take a longer time to stabilize their performance in the 2D inversion condition. Fitts' law is robust under all visual conditions. The eye-hand incompatibility increases movement time with 2D inversion taking the longest movement time. Movement time (MT) was split into initiation time (IT), distance covering time (DCT) and acquisition time (AT) based on submovements. The distance covering part is the first submovement that is primarily ballistic and covers around 90% or more of total amplitude. Furthermore, AT allows the aimed movement to be split into two phases: ballistic and visual control. The results show that the transition from ballistic to visual control happens at lower Index of difficulty (ID) values as the level of incompatibility increases. Based on the experiment and prior research, it is appropriate to use the model MT = a + b ID + c√A as it can account for the two phases of ballistic and visual control.

The Potential of Game-Based Digital Biomarkers for Modeling Mental Health

BACKGROUND

Assessment for mental health is performed by experts using interview techniques, questionnaires, and test batteries and following standardized manuals; however, there would be myriad benefits if behavioral correlates could predict mental health and be used for population screening or prevalence estimations. A variety of digital sources of data (eg, online search data and social media posts) have been previously proposed as candidates for digital biomarkers in the context of mental health. Playing games on computers, gaming consoles, or mobile devices (ie, digital gaming) has become a leading leisure activity of choice and yields rich data from a variety of sources.

OBJECTIVE

In this paper, we argue that game-based data from commercial off-the-shelf games have the potential to be used as a digital biomarker to assess and model mental health and health decline. Although there is great potential in games developed specifically for mental health assessment (eg, Sea Hero Quest), we focus on data gathered "in-the-wild" from playing commercial off-the-shelf games designed primarily for entertainment.

METHODS

We argue that the activity traces left behind by natural interactions with digital games can be modeled using computational approaches for big data. To support our argument, we present an investigation of existing data sources, a categorization of observable traits from game data, and examples of potentially useful game-based digital biomarkers derived from activity traces.

RESULTS

Our investigation reveals different types of data that are generated from play and the sources from which these data can be accessed. Based on these insights, we describe five categories of digital biomarkers that can be derived from game-based data, including behavior, cognitive performance, motor performance, social behavior, and affect. For each type of biomarker, we describe the data type, the game-based sources from which it can be derived, its importance for mental health modeling, and any existing statistical associations with mental health that have been demonstrated in prior work. We end with a discussion on the limitations and potential of data from commercial off-the-shelf games for use as a digital biomarker of mental health.

CONCLUSIONS

When people play commercial digital games, they produce significant volumes of high-resolution data that are not only related to play frequency, but also include performance data reflecting low-level cognitive and motor processing; text-based data that are indicative of the affective state; social data that reveal networks of relationships; content choice data that imply preferred genres; and contextual data that divulge where, when, and with whom the players are playing. These data provide a source for digital biomarkers that may indicate mental health. Produced by engaged human behavior, game data have the potential to be leveraged for population screening or prevalence estimations, leading to at-scale, nonintrusive assessment of mental health.

Kinematic analysis of direct pointing in projection-based stereoscopic environments

This work investigated the effects of visual information, parallax, and target positions on movement performances in projection-based stereoscopic displays (PSDs). Fifteen (26.5 ± 3.83 years) self-declared right-handed individuals, with normal or corrected to normal visual acuity, completed pointing tasks in stereoscopic and real environments (RE). Three-dimensional spatial data, recorded by a motion system composed of six infrared cameras, was used to compute kinematics of reaching a real/virtual object at a combination of three parallax and nine frontal planar positions. The results indicated that movement in the PSD was slower and needed longer confirmation time than that in the RE. This might be because of the difficulty and misperception of distance associated with PSD. The motions were initiated faster but took longer to complete in vision-based conditions. The overall kinematic parameters were better as targets were presented closer to participants and around the center of displays. However, during pointing at a target that was continuously visible or presented briefly and disappeared, participants applied similar movement strategies to approach the visual objects. The comparable kinematics and movement behaviors in stereoscopic displays encourage the use of direct pointing that would enhance reaching and grasping tasks - which are important in applications such as rehabilitation, surgical training, and other programs that employ upper limbs. In addition, the more natural interaction by direct pointing minimizes the effort of learning new skills to use other devices.

Psychomotor Performance of Input Device Users and Optimized Cursor Control

This study examined the fit of the stochastic optimized submovement model (= SOS model; Meyer, Abrams, Kornblum, Wright and Smith, 1988) for cursor movements of two laptop input devices. 10 experienced users of touchpad (easy sensorimotor transformation) and 10 experts for the trackpoint (difficult sensorimotor transformation) executed clicking tasks. Given a model fit, the aim of the study was to discuss the well-known performance inferiority of input devices with difficult sensori-motor transformations on the basis of the SOS model. Cursor movements of both, touchpad and trackpoint, showed a basic fit with the SOS model. With the touchpad, the cursor was easier to control, resulting in a good performance: fewer submovements were carried out from the start to the target, and cursor velocity and acceleration were comparably low. Contrary, with the trackpoint cursor control was more difficult, accompanied by more submovements and a high inaccurateness in the target area: thus, even for experts, the difficult sensorimotor transformation of the trackpoint interfered with a proper motor execution. Actual and potential applications of this research include an optimization of cursor control for input devices and guidelines for their users.

The Effects of Selection Technique on Target Acquisition Movements Made with a Mouse

Research has shown that a significant amount of the time needed to acquire on-screen targets with a mouse can be spent in the selection phase. Thus we are exploring alternative modes of target selection that may reduce this time. In the present experiment, participants acquired targets of varying distance and size. Two methods for target selection were compared: (1) the standard button-select technique, (2) and a mouse-over technique, in which targets were designated when the cursor and target were superpositioned for 350 ms. Results showed that target-acquisition times were significantly shorter for the mouse-over technique, particularly at the smallest target size. There was also evidence that the effects were localized in the selection phase. Overall, the results suggest that the mouse-over technique can be an effective alternative to selelcting targets via button press. Potential applications and limitations of this procedure are discussed.

Empirical evaluation of circling interface with head-mounted mouse emulator users

PURPOSE

To evaluate the performance of the circling interface, which is an alternative interaction method for selecting and manipulating on-screen objects based on circling the target, rather than pointing and clicking.

METHOD

We conducted empirical evaluations with actual head-mounted mouse emulator users from two different groups: individuals with spinal cord injury (SCI) and individuals with cerebral palsy (CP), comparing each group's performance and satisfaction level on pointing tasks with the circling interface to performance on the same tasks when using dwell-clicking software.

RESULTS

Across all operations, for both subjects with SCI and with CP, the circling interface showed faster performance than the dwell-clicking interface. For the single-click operation, the circling interface showed slower performance than dwell selection, but for both double-click and drag-and-drop operations, the circling interface produced faster performance. Subjects with CP required much longer time to complete the tasks compared to subjects with SCI. If errors caused by circling on an area with no target and unintentional circling caused by jerky movements and an abnormally tiny circle are automatically corrected by the circling interface, their performance accuracy with the circling interface outperformed existing solutions without a steep learning curve.

CONCLUSIONS

Circling interface can be used in conjunction with existing techniques and this kind of combined approach achieve more effective mouse use for some individuals with pointing problems. It is also expected to be useful for both computer access and augmentative communication software. Implications for Rehabilitation A circling interface will improve clinical practice by providing an alternative pointing method that does not require physically activating mouse buttons and is more efficient than dwell-clicking. Being used in conjunction with existing techniques, some individuals who are head mouse users can achieve more effective mouse use. The Circling interface can also work with AAC devices.

Circling motion and screen edges as an alternative input method for on-screen target manipulation

PURPOSE

To investigate a new alternative interaction method, called circling interface, for manipulating on-screen objects. To specify a target, the user makes a circling motion around the target. To specify a desired pointing command with the circling interface, each edge of the screen is used. The user selects a command before circling the target.

METHOD

To evaluate the circling interface, we conducted an experiment with 16 participants, comparing the performance on pointing tasks with different combinations of selection method (circling interface, physical mouse and dwelling interface) and input device (normal computer mouse, head pointer and joystick mouse emulator).

RESULTS

A circling interface is compatible with many types of pointing devices, not requiring physical activation of mouse buttons, and is more efficient than dwell-clicking. Across all common pointing operations, the circling interface had a tendency to produce faster performance with a head-mounted mouse emulator than with a joystick mouse. The performance accuracy of the circling interface outperformed the dwelling interface.

CONCLUSIONS

It was demonstrated that the circling interface has the potential as another alternative pointing method for selecting and manipulating objects in a graphical user interface. Implications for Rehabilitation A circling interface will improve clinical practice by providing an alternative pointing method that does not require physically activating mouse buttons and is more efficient than dwell-clicking. The Circling interface can also work with AAC devices.

Fitts' Law With An Average of Two or Less Submoves?

A number of researchers have noted that, with as few as 2 submovements (primary and corrective), the movement time versus index of difficulty (ID) data are described by Fitts' law, that is, there is a linear relationship between movement time (MT) and ID. A model is presented that shows that there may be an apparent relationship of this form between MT and ID with only 2 submovements. The model is based on the characteristics of ballistic movements and the required corrections to the endpoint of the primary submovement. The model shows the close relationship between the ballistic distance-covering phase of a movement and the consequent Fitts' law. The model is tested against several data sets and found to give a good description of the aiming process.

A Nonlinear Model for Mouse Pointing Task Movement Time Analysis Based on Both System and Human Effects

This paper provides a detailed model for analyzing movement time performance during rapid goal-directed point- and-click motions with a computer mouse. Twelve typically developed individuals and eleven youths with cerebral palsy conducted point and click computer tasks from which the model was developed. The proposed model is nonlinear and based on both system (target width and movement amplitude) and human effects (erroneous clicks, number of submovements, number of slip-offs, curvature index, and average speed). To ensure successful targeting by youths with cerebral palsy, the index of difficulty was limited to a range of 1.58 - 3.0 bits. For consistency, the same range was used with both groups. The most significant contributing human effect to movement time was found to be the curvature index for both typically developed individuals and individuals with cerebral palsy. This model will assist in algorithm development to improve cursor speed and accuracy for youths with cerebral palsy.

A cross-sectional study examining computer task completion by adolescents with cerebral palsy across the Manual Ability Classification System levels

AIM

The aim of this study was to analyze the cursor trajectories of adolescents with cerebral palsy (CP) when using a mouse for point-and-click computer tasks. By identifying some of the factors limiting cursor movement and gaining a better understanding of human movement, it will be possible to design more accessible computer interfaces.

METHOD

This study evaluated cursor trajectories of 29 individuals with bilateral CP who had different levels of upper limb function as measured by the Manual Ability Classification System, and compared the results with those of 12 adolescents with typical development.

RESULTS

Among adolescents with typical development, movement time increases linearly as the index of difficulty increases (Fitts' law); however, this linearity was not apparent in adolescents with bilateral CP.

INTERPRETATION

Interfaces for members of the population are designed around Fitts' law, with low precision requirements at indices of difficulty lower than 4. We found that interactive displays for adolescents with CP should be limited to an index of difficulty of 2.

Distinguishing Users By Pointing Performance in Laboratory and Real-World Tasks

Accurate pointing is an obstacle to computer access for individuals who experience motor impairments. One of the main barriers to assisting individuals with pointing problems is a lack of frequent and low-cost assessment of pointing ability. We are working to build technology to automatically assess pointing problems during every day (or real-world) computer use. To this end, we have gathered and studied real-world pointing use from individuals with motor impairments and older adults. We have used this data to develop novel techniques to analyze pointing performance. In this article, we present learned statistical models that distinguish between pointing actions from diverse populations using real-world pointing samples. We describe how our models could be used to support individuals with different abilities sharing a computer, or one individual who experiences temporary pointing problems. Our investigation contributes to a better understanding of real-world pointing. We hope that these techniques will be used to develop systems that can automatically adapt to users’ current needs in real-world computing environments.

Interaction of tremor and magnification in a motor performance task with visual feedback

In this study, the interaction between increased gain in the visual feedback loop and motor control of the periphery was investigated. Participants (N = 15) were asked to maintain a constant finger position while they used magnified visual feedback. The measure of the accuracy of each trial was the standard deviation (trial error) of the finger position. Trials performed under magnification had lower trial errors than trials without magnification. The change in trial error between trials with and without magnification proved greater than the difference between trials at any 2 magnifications. In contrast, the differences between individual subjects were often greater than the differences between performances at individual magnifications. At higher magnifications, performance seemed to be limited by the tremor; the ratio of trial error to tremor intensity was constant. When applied to microsurgery, the present results accord with those found in earlier research, including investigations that have found that the level of magnification used in microsurgery is not the most significant factor in achieving good results and that tremor is the limiting factor in microsurgical tasks.

Insights from dividing 3D goal-directed movements into meaningful phases

A new method for analyzing 3D goal-directed movements provides more insights than existing approaches by dividing them into meaningful phases. An experiment applying a simple 3D task, resembling a standardized 2D multidirectional pointing task, yielded insights that can help researchers better identify input devices' and interaction techniques' strengths and weaknesses.

Discoveries and developments in human-computer interaction

OBJECTIVE

This paper describes contributions made to the science and practice of human-computer interaction (HCI), primarily through Human Factors and the society's annual proceedings.

BACKGROUND

Research in HCI began to appear in publications associated with the Society around 1980 and has continued through the present.

METHOD

A search of the literature appearing in either the journal or the proceedings was done to identify the specific contributions made by researchers in this area.

RESULTS

More than 2,300 papers were identified, some comparing the actual or predicted performance of a new device, display format, or computer-based system with an existing or alternative system. Other work describes methods for evaluating systems performance.

CONCLUSION

This work has had a tremendous impact, particularly the work of Fitts, Smith and Mosier, and Virzi.

APPLICATION

Work on HCI has contributed to (a) current national and international guidelines, (b) the development of user interface management systems, (c) the provision of guidance as to where best to invest resources when evaluating computing systems, and (d) the prediction of human performance using those systems.

Goal Crossing with Mice and Trackballs for People with Motor Impairments

Prior research shows that people with motor impairments face considerable challenges when using conventional mice and trackballs. One challenge is positioning the mouse cursor within confined target areas; another is executing a precise click without slipping. These problems can make mouse pointing in graphical user interfaces very difficult for some people. This article explores goal crossing as an alternative strategy for more accessible target acquisition. In goal crossing, targets are boundaries that are simply crossed by the mouse cursor. Thus, goal crossing avoids the two aforementioned problems. To date, however, researchers have not examined the feasibility of goal crossing for people with motor difficulties. We therefore present a study comparing area pointing and goal crossing. Our performance results indicate that although Fitts' throughput for able-bodied users is higher for area pointing than for goal crossing (4.72 vs. 3.61 bits/s), the opposite is true for users with motor impairments (2.34 vs. 2.88 bits/s). However, error rates are higher for goal crossing than for area pointing under a strict definition of crossing errors (6.23% vs. 1.94%). We also present path analyses and an examination of submovement velocity, acceleration, and jerk (the change in acceleration over time). These results show marked differences between crossing and pointing and almost categorically favor crossing. An important finding is that crossing reduces jerk for both participant groups, indicating more fluid, stable motion. To help realize the potential of goal crossing for computer access, we offer design concepts for crossing widgets that address the occlusion problem, which occurs when one crossing goal obscures another in persistent mouse-cursor interfaces. This work provides the motivation and initial steps for further exploration of goal crossing on the desktop, and may help researchers and designers to radically reshape user interfaces to provide accessible goal crossing, thereby lowering barriers to access.

Sensumotor transformation of input devices and the impact on practice and task difficulty

In the present study, the usability of two laptop input devices, touchpad and trackpoint, is evaluated. The focus is set on the impact of sensumotor transformation of input devices on practice and task difficulty. Thirty novices and 14 experts operated either touchpad or trackpoint over a period of 1600 trials of a point-click task. As hypothesized, novices and experts operated the touchpad by 15% faster compared to the trackpoint. For novices, performance rose distinctly and levelled off after 960 trials. This consolidation occurred earlier than reported in literature (1400-1600 trials) and, contrary to the assumption, learning was similar for touchpad and trackpoint. The impact of task difficulty dropped remarkably by practice, which points at a more general than specific task learning. In conclusion, ergonomic guidelines can be derived for the user-specific optimization of the usage of touchpad and trackpoint. Actual and potential applications of this research include the user-specific optimization of laptop input devices. Within the theoretical framework of psychomotor models, a profound knowledge of user behaviour in human-computer interaction is provided. Ergonomic guidelines can be derived for the efficient usage of laptop input devices and an optimized hardware and software design.

Design and feasibility study of an integrated pointing device apparatus for individuals with spinal cord injury

Despite the commercial availability of numerous computer-pointing devices, many severely disabled individuals still rely on customized equipment to operate computers. This study presents a novel Integrated Pointing Device Apparatus (IPDA) that integrates numerous commercial pointing devices. The novel IPDA, which complies with a standard USB 1.1 interface, is compatible with most tested computer-pointing devices and flexibly integrates commercial computer devices, tailoring them to suit individual needs. By using simple integrated circuit design and low-cost electronic components, this low-cost apparatus is easily maintained. The feasibility of the IPDA was evaluated by four subjects with high-level cervical (C4-5) spinal cord injury (SCI). Participants performed normal move-and-click and drag-and-drop tasks typically performed by computer pointing devices. Each participant not able to use a traditional computer mouse or trackball were able to operate a computer adequately with the IPDA and three including one operating a trackball with his chin, operated computers easily and smoothly. This feasibility study showed that the IPDA effectively integrates commercial pointing devices, thereby providing the possibility for some people with SCI to obtain computer operability. This study demonstrated the advantages of flexibility, low cost, and acceptable efficiency of the novel IPDA.

Kinematic analysis of multiple constraints on a pointing task

The current experiment suggests that the speed/accuracy tradeoff is composed of two classes of constraints, effector and task. We examined the effects of movement distance, target size, orientation of the movement in the workspace, and C-D gain on the kinematics of discrete pointing movements made with computer mouse. It was found that target size influenced the shape of velocity profiles by elongating the duration of the corrective sub-movement phase, while movement distance scaled the entire velocity curve without affecting its shape. C-D gain and orientation of the movement exhibited two kinds of effects: an overall scaling of the velocity curve and a change in its shape. We conclude that target size is a task constraint and movement distance is an effector constraint, while movement orientation exhibited characteristics of both. C-D gain by itself was not a constraint, but interacted with both task and effector constrains. These results highlight the roles of biomechanical and information processing factors in the speed/accuracy tradeoff.

Forward/up directional incompatibilities during cursor placement within graphical user interfaces

Within graphical user interfaces, an indirect relationship between display and control may lead to directional incompatibilities when a forward mouse movement codes upward cursor motions. However, this should not occur for left/right movements or direct cursor controllers (e.g. touch sensitive screens). In a four-choice reaction time task, 12 participants performed movements from a central start location to a target situated at one of four cardinal points (top, bottom, left, right). A 2 x 2 x 2 design varied directness of controller (moving cursor on computer screen or pen on graphics tablet), compatibility of orientation of cursor controller with screen (horizontal or vertical) and axis of desired cursor motion (left/right or up/down). Incompatibility between orientation of controller and motion of cursor did not affect response latencies, possibly because both forward and upward movements are away from the midline and go up the visual field. However, directional incompatibilities between display and controller led to slower movement with prolonged accelerative phases. Indirect relationships between display and control led to less efficient movements with prolonged decelerative phases and a tendency to undershoot movements along the bottom/top axis. More direct cursor control devices, such as touch sensitive screens, should enhance the efficiency of aspects of cursor trajectories.

Touch a screen or turn a knob: choosing the best device for the job

Input devices enable users to interact with systems. In two experiments, we assessed whether and how task demands and user age influenced task performance for a direct input device (touch screen) and an indirect input device (rotary encoder). In Experiment 1, 40 younger (18-28 years) and 40 middle-aged to older adults (51-65 years) performed tasks using controls such as sliders, up/down buttons, list boxes, and text boxes while using a system. The optimal input device to facilitate performance was dependent on the task being performed and the age of the user. In Experiment 2, touch screen use was assessed for 20 younger (19-23 years) and 20 older adults (51-70 years). Task demands were manipulated through button size, movement distance, direction, and type of movement. Performance was moderated by the age of the user and by task demands. Actual or potential applications of this research include guidance for the optimal selection of input devices for different user populations and task characteristics.

Mouse movements of motion-impaired users: a submovement analysis

Understanding human movement is key to improving input devices and interaction techniques. This paper presents a study of mouse movements of motion-impaired users, with an aim to gaining a better understanding of impaired movement. The cursor trajectories of six motion-impaired users and three able-bodied users are studied according to their submovement structure. Several aspects of the movement are studied, including the frequency and duration of pauses between submovements, verification times, the number of submovements, the peak speed of submovements and the accuracy of submovements in two-dimensions. Results include findings that some motion-impaired users pause more often and for longer than able-bodied users, require up to five times more submovements to complete the same task, and exhibit a correlation between error and peak submovement speed that does not exist for able-bodied users.

Conflicting directional and locational cues afforded by arrowhead cursors in graphical user interfaces

Task-irrelevant features of arowhead cursors may generate conflict during cursor placement within graphical user interfaces. Arrowheads can signify location, but also cue direction and feature in optical illusions. To address the influence of conflicting cues, 14 participants used arrowhead cursors (standard, oversized) pointing upward or downward to move to targets (7.5, 15-mm diameter) situated at the top or bottom of the screen. Compatible arrowhead orientation improved response initiation. Cursor size, orientation, direction of motion, and target size interacted during cursor movement. Overshooting occurred for oversized cursors in the direction the arrow pointed for larger targets. Larger compatible arrowhead cursors elicit less efficient cursor positioning movements that are more susceptible to illusory processes, posing implications for design of cursors and graphical user interfaces.

Characteristics of cursor trajectories controlled by the computer mouse

An analysis of computer screen cursor trajectories can provide insights into the factors limiting efficient cursor positioning and can assist in the design of human-computer interfaces. Cursor locations as controlled by a Microsoft computer mouse with standard settings were therefore sampled at 5 ms intervals and kinematic analyses addressed the proportions of time spent in the initiation, accelerative and terminal guidance phases of cursor positioning. Twelve participants used a computer mouse to move a cursor over different distances (7.5 cm, 15 cm) from a home location in the lower centre of the screen to targets of different diameters (8 mm, 16 mm), situated to the left, middle or right of the computer screen. Cursor trajectories were irregular, and participants regularly overshot their targets, spending 70% of movement duration in terminal guidance. Participants appeared to use the initial part of their movement to establish mappings between controller and display. Interventions should seek to reduce the terminal guidance phase of cursor positioning.

Age differences in remote pointing performance

The purpose of this study was to investigate age differences in remote pointing movements. The subjects were recruited from three age groups (ages 18-22 yr., 40-50 yr., and 60-70 yr., with 9 men and 9 women in each group). They were required to perform cursor-positioning tasks using a remote pointing device, in which the dependent measures were the time taken to reposition the cursor and the accuracy of subjects' movement trajectories. The movement time was further separated into two components, First Submovement duration and Adjustment Submovement duration. Analysis indicated that age groups showed reduced performance on remote pointing. Moreover, remote positioning movement for the young-adult group was mostly completed in their First Submovement phase, while the elderly subjects spent most of their movement time on the Adjustment Submovement phase. These results support the proposition that different age groups exhibit different kinds of movement patterns.

Aggregation bias and the use of regression in evaluating models of human performance

Regression analyses are increasingly being used to provide confirmatory evidence for models of human performance. The amount of information made available to judge these models is reduced because clearly established standards in the techniques of performing and reporting regression analyses are lacking. This paper addresses two primary problems in regression analysis: aggregation of data and the aggregation of variables into composite models. We provide examples of the misuse of regression techniques and recommend ways in which the amount of information made available to evaluate the model being tested can be maximized in analysis and reporting.