Design and evaluation of a curved computer keyboard

Conventional, straight keyboards remain the most popular design among keyboards sold and used with personal computers despite the biomechanical benefits offered by alternative keyboard designs. Some typists indicate that the daunting medical device-like appearance of these alternative ‘ergonomic’ keyboards is the reason for not purchasing an alternative keyboard design. The purpose of this research was to create a new computer keyboard that promoted more neutral postures in the wrist while maintaining the approachability and typing performance of a straight keyboard. The design process created a curved alphanumeric keyboard, designed to reduce ulnar deviation, and a built-in, padded wrist-rest to reduce wrist extension. Typing performance, wrist postures and perceptions of fatigue when using the new curved keyboard were compared to those when using a straight keyboard design. The curved keyboard reduced ulnar deviation by 2.2° ± 0.7 (p < 0.01). Relative to the straight keyboard without a built-in wrist-rest, the prototype curved keyboard with the built-in padded wrist-rest reduced wrist extension by 6.3° ± 1.2 (p < 0.01). There were no differences in typing speed or accuracy between keyboards. Perceived fatigue ratings were significantly lower in the hands, forearms and shoulders with the curved keyboard. The new curved keyboard achieved its design goal of reducing discomfort and promoting more neutral wrist postures while not compromising users' preferences and typing performance.     

Investigating touchscreen typing: the effect of keyboard size on typing speed

Two studies investigated the effect keyboard size has on typing speed and error rates for touchscreen keyboards using the lift-off strategy. A cursor appeared when users touched the screen and a key was selected when they lifted their finger from the screen. Four keyboard sizes were investigated ranging from 24.6 cm to 6.8 cm wide. Results indicate that novices can type approximately 10 words per minute (WPM) on the smallest keyboard and 20 WPM on the largest. Experienced users improved to 21 WPM on the smallest keyboard and 32 WPM on the largest. These results indicate that, although slower, small touchscreen keyboards can be used for limited data entry when the presence of a regular keyboard is not practical. Applications include portable pocket-sized or palmtop computers, messaging systems, and personal information resources. Results also suggest the increased importance of experience on these smaller keyboards. Research directions are suggested.     

Performance effects of reduced proprioceptive feedback on touch typists and casual users in a typing task

This study examined performance and acceptance effects of lack of kinesthetic and tactile feedback from the keyboard in a typing task with two subject groups of differing skill level: touch typists and casual users. Subjects' objective performance (e.g., speed, accuracy, throughput) and subjective acceptance (questionnaire) was evaluated for both a conventional full travel keyboard and a prototype piezoelectric flat keyboard which lacked familiar kinesthetic and tactile feedback. Any performance decrement present with the flat keyboard was expected to diminish with practice for the touch typists due to transfer and adaptation of typing skills. Performance for both subject groups was significantly higher with the conventional keyboard and touch typists' performance was more adversely affected by the flat keyboard than casual users'. No performance improvement with practice was found for one subject group relative to the other or for one keyboard relative to the other. It was concluded the touch typists were unable to adapt to the unusual feedback conditions present with the piezo-electric fiat keyboard.     

Exploring touch feedback display of virtual keyboards for reduced eye movements

When typing on smartphones or palm tablets, users generally make an effort to type correctly while simultaneously checking the small keyboard and the text display. Unlike physical keyboards that allow users to perform typing based on long-term muscle memory, virtual keyboards typically require more frequent eye movements between the keyboard and the text display areas.This study proposes a new way of designing a virtual keyboard display to reduce the effort associated with frequent eye-movements. For this study, we developed virtual keyboard display systems featuring both static and dynamic word-by-word (WBW) feedback displays. The two display systems were examined in comparison with a more conventional method known as character-by-character (CBC) feedback display. We investigated user satisfaction, typing performance and the user’s eye gaze shifts. Eye gaze shifts were measured between the keyboard and the text display areas across the three conditions using self-report, log, and eye-tracking measures. In the static WBW condition, the words being typed displayed in a fixed area at the top of the virtual keyboard; in the dynamic WBW display, the words displayed in a small popup window at the tip of the selected key.Using a repeated measure experiment for the three display conditions, participants were asked to type fifteen phrases using a palm tablet while wearing eye-tracking glasses for each condition. We conducted a mixed-model design ANOVA with group (SLOW vs. FAST typing; men vs. women) as between-subject factors and display condition (CBC vs. WBW). We found a significant (11%) improvement in typing speed with the dynamic WBW over the CBC display for less experienced keyboard users. In addition, participants reported higher satisfaction with the two WBW conditions than the CBC condition. Eye fixations, dwell times, and heat map data also supported that WBW displays are advantageous for less experienced, slower typists by helping them stay focused more on the keyboard, thus reducing eye transitions to the text display. Our study systematically demonstrates how and to what extent the virtual keyboard display strategy influences typing performance and subjective experience based on self-reports and eye-tracking measures. The approach and findings of this study should provide useful information and practical guidance to mobile application developers and designers who are interested in improving virtual keyboard functionalities and user satisfaction.     

Differences in computer exposure between university administrators and CAD draftsmen

This study utilized an external logger system for onsite measurements of computer activities of two professional groups—twelve university administrators and twelve computer-aided design (CAD) draftsmen. Computer use of each participant was recorded for 10 consecutive days—an average of 7.9 ± 1.8 workdays and 7.8 ± 1.5 workdays for administrators and draftsmen, respectively. Quantitative parameters computed using recorded data were daily dynamic duration (DD) and static duration, daily keystrokes, mouse clicks, wheel scrolling counts, mouse movement and dragged distance, average typing and clicking rates, and average time holding down keys and mouse buttons. Significant group differences existed in the number of daily keystrokes (p < 0.0005) and mouse clicks (p < 0.0005), mouse distance moved (p < 0.0005), typing rate (p < 0.0001), daily mouse DD (p < 0.0001), and keyboard DD (p < 0.005). Both groups had significantly longer mouse DD than keyboard DD (p < 0.0001). Statistical analysis indicates that the duration of computer use for different computer tasks cannot be represented by a single formula with same set of quantitative parameters as those associated with mouse and keyboard activities. Results of this study demonstrate that computer exposure during different tasks cannot be estimated solely by computer use duration. Quantification of onsite computer activities is necessary when determining computer-associated risk of musculoskeletal disorders. Other significant findings are discussed.     

Postures,typing strategies,and gender differences in mobile device usage: An observational study

Mobile device text messaging and other typing is rapidly increasing worldwide. A checklist was utilized to characterize joint postures and typing styles in individuals appearing to be of college age (n = 859) while typing on their mobile devices in public. Gender differences were also ascertained. Almost universally, observed subjects had a flexed neck (91.0%, n = 782), and a non-neutral typing-side wrist (90.3%, n = 776). A greater proportion of males had protracted shoulders (p < 0.01, χ² test), while a greater proportion of females had a typing-side inner elbow angle of <90°, particularly while standing (p = 0.03, χ² test). 46.1% of subjects typed with both thumbs (two hands holding the mobile device). Just over one-third typed with their right thumb (right hand holding the mobile device). No difference in typing styles between genders was found. Future research should determine whether the non-neutral postures identified may be associated with musculoskeletal disorders.     

Effects of a vertical keyboard design on typing performance, user comfort and muscle tension

To circumvent the awkward pronated hand position inherent to conventional horizontal keyboards, a vertical, split keyboard was designed with flexible cushions supporting the wrists, allowing relaxed hand and arm postures. During eight twice-weekly 30-min training sessions, the performance and subjective comfort of nine experienced typists were tested. Typing speed and error percentage, and surface electromyographic activity of six forearm muscles and two postural muscles were recorded in separate sessions at the end of each week. Typing speed rapidly recovered to the preset rate of 300 keystrokes/min and error percentages were similar for the two keyboards. The vertical keyboard caused lower muscular activity in especially finger extensor muscles, did not increase postural muscle activity, and self-reported comfort was higher. Thus, the vertical keyboard was easily mastered, was experienced as comfortable, and caused less stress on muscles sensitive to repetitive strain injuries.     

A review of: “Applying Psychology: Understanding People” By R. C. Beck (New Jersey: Prentice Hall, 1982.) [Pp.484.] $15-70. ISBN 0-13-043463-9.

This study investigated how ergonomic design influences neck-and-shoulder muscle strain, through keyboard assessment. Muscular activity was measured electromyographically (EMG) from six muscles in the forearm and shoulders of eight experienced typists using each of five different types of keyboard: one mechanical, one electromechanical, and one electronic typewriter; one personal computer/word processor (PC-XT) keyboard; and one angled at 20° in the horizontal plane. The impact on muscular activity of using a palmrest was also studied. The mechanical typewriter induced a higher strain in the forearm and finger muscles than did the modern typewriters and keyboards. These induced no different strain on the neck-and-shoulder muscles, except for the right shoulder muscle, which was more active with the electronic typewriter than with the other machines. Using a palmrest did not decrease the strain on the muscles investigated. Use of the ‘angled’ PC-XT keyboard did not influence the measured muscular load on the forearm and finger muscles compared to typing on an ordinary PC-XT keyboard, but decreased the extensor muscular strain compared to the electronic typewriter.     

An evaluation of the ergonomics of three computer keyboards

The influence of keyboard design on hand position, typing productivity and keyboard preference was evaluated by comparing two segmented alternative designs with the linear standard keyboard. The FIXED alternative keyboard featured a split angle of 12 degrees and a moderate lateral inclination angle of 10 degrees. The adjustable OPEN alternative keyboard was used with a 15 degrees split setting, which resulted in a marked 42 degrees of demiboard lateral inclination. Sixteen typists, who completed 10 h of training on both alternative keyboards, were videotaped while typing set texts on all three keyboards. Forearm and wrist angles based on three-dimensional video analyses were significantly different (p<0.05) among the three designs tested. Both alternative keyboards placed the forearm and wrist closer to neutral positions than did the standard keyboard. While the OPEN keyboard reduced pronation, it simultaneously increased radial deviation. The FIXED keyboard kept the forearm in moderate pronation and the wrist closer to neutral. More time was spent in neutral and moderate ranges of wrist motion when subjects typed on the FIXED compared with the other two designs. With respect to the standard keyboard, typing productivity was reduced by 10% on the FIXED and 20% on the OPEN designs. No significant difference in preference was found between the standard and FIXED keyboards, both of which were preferred over the OPEN. It was concluded that, of the three keyboards evaluated, the FIXED design incorporated moderate changes to the standard keyboard. These changes promoted a more natural hand position while typing thereby reducing the potential for cumulative trauma disorders of the wrist. In addition, the FIXED design preserved a reasonable level of productivity and was well accepted by users.     

Effect of key size and activation area on the performance of a regional error correction method in a touch-screen QWERTY keyboard

Manual text entry, which is one of the main features of mobile communications devices, decreases the competitive advantages of full touch-screen interfaces over physical interfaces. Especially for small full QWERTY keyboards, text entry becomes more problematic because of the small size of the virtual keys, absence of tactile feedback, and occlusion of virtual keys by fingers. One solution to this problem is the regional error correction, which is a predictive text entry method that activates the key corresponding to the actual activation point and also other keys within an activation area. This study investigates how the size of keys and of the activation area affect the accuracy of the regional error correction and compares the regional error correction method with the conventional finger touch method, for a touch-screen QWERTY keyboard. The regional error correction reduced both the time and the number of touches required to complete text entry when keys were small, but no difference was observed when keys were large. Users’ subjective assessments of ease of use and preference indicated greater satisfaction with the regional error correction method than without it, regardless of key size.Relevance to industry: The result of this study can be used to speed and simplify text entry in mobile devices with full-QWERTY virtual keyboards.     

Skill-level based examination of forearm muscle activation associated with efficient wrist and finger movements during typing

This study aims to elucidate the relationship between the wrist and finger movements and forearm muscle activation of twelve young people (age: 21.1 ± 0.76 years, nine men and three women) with different typing skills. We hypothesize that skilled typists (STs) could move their wrist and finger joints faster than unskilled typists (UTs) because they could efficiently use their muscles according to the activity characteristics of the flexors and extensors of the wrist joint. We measured wrist and finger movements using a 3D motion capture system and forearm muscle activation using surface electromyography during the typing task. We analyzed the entire task and the time when the U key was entered during the same task. The angular velocity of the wrist and finger flexion/extension and the muscle activation of the wrist flexors was higher in the STs than in the UTs, while the muscle activation of the wrist extensors was higher in the latter than that in the former. Our results showed that STs may have used their forearm muscles to take advantage of the physical characteristics of the keys and the spring characteristics of their muscles and tendons. It was suggested that they placed less mechanical stress on their finger muscles and tendons when pressing and releasing the keys.     

Effect of keyswitch design of desktop and notebook keyboards related to key stiffness and typing force

This study aimed to compare and analyse rubber-dome desktop, spring-column desktop and notebook keyboards in terms of key stiffness and fingertip typing force. The spring-column keyboard resulted in the highest mean peak contact force (0.86N), followed by the rubber dome desktop (0.68N) and the notebook (0.59N). All these differences were statistically significant. Likewise, the spring-column keyboard registered the highest fingertip typing force and the notebook keyboard the lowest. A comparison of forces showed the notebook (rubber dome) keyboard had the highest fingertip-to-peak contact force ratio (overstrike force), and the spring-column generated the least excess force (as a ratio of peak contact force). The results of this study could aid in optimizing computer key design that could possibly reduce subject discomfort and fatigue.     

Effect of keyswitch design of desktop and notebook keyboards related to key stiffness and typing force

This study aimed to compare and analyse rubber-dome desktop, spring-column desktop and notebook keyboards in terms of key stiffness and fingertip typing force. The spring-column keyboard resulted in the highest mean peak contact force (0.86N), followed by the rubber dome desktop (0.68N) and the notebook (0.59N). All these differences were statistically significant. Likewise, the spring-column keyboard registered the highest fingertip typing force and the notebook keyboard the lowest. A comparison of forces showed the notebook (rubber dome) keyboard had the highest fingertip-to-peak contact force ratio (overstrike force), and the spring-column generated the least excess force (as a ratio of peak contact force). The results of this study could aid in optimizing computer key design that could possibly reduce subject discomfort and fatigue.     

Total forearm support during a typing task may reduce the risk of Trapezius' Myalgia development

ObjectiveEvaluate the influence of alternating the position of the upper limbs, between fully supported and unsupported forearms, in the Upper Trapezius (UT) activity during a typing task on a straight-edged desk.BackgroundErgonomic barriers, such as reduced desk area, is one of the reasons that force computer users to work without supporting their forearms. Unsupported forearms may lead to increased UT muscle fatigue, increasing the potential for lesions, with Trapezius Myalgia (TM) being a possible outcome.Method15 healthy volunteers were assessed (6 females, average age of 3,7 ± 9,5 years old). The protocol included an alternated position of forearms every 5 min between fully supported and unsupported forearms, with a 20-min total duration of a typing task. Surface electromyography readings were collected from both UTs.ResultsSignificant differences were found in the variation of the EMG signal between the two positions for the non-dominant arm after 10 min (p < .05) of typing. The non-dominant UT registered higher levels of activity than the dominant UT. Supported forearms reduced the electrical activity in both UTs, with a greater difference in the non-dominant.ConclusionThis study consolidates the current knowledge that unsupported upper limb during typing tasks significantly increases UT's electrical activity. By fully supporting the forearm, that activity is reduced. Females and the non-dominant UT showed higher electrical activity, potentially increasing the risk of developing TM.ApplicationHealthcare providers, safety and health professionals, and ergonomists should be mindful of the forearm position when advising computer users to prevent TM.     

Effects of negatively sloped keyboard wedges on risk factors for upper extremity work-related musculoskeletal disorders and user performance

Several changes to computer peripherals have been developed to reduce exposure to identified risk factors for musculoskeletal injury, notably in keyboard designs. Negative keyboard angles and their resulting effects on objective physiological measures, subjective measures and performance have been studied, although few angles have been investigated despite the benefits associated with their use. The objective of this study was to quantify the effects of negative keyboard angles on forearm muscle activity, wrist posture, key strike force, perceived discomfort and performance and to identify a negative keyboard angle or range of keyboard angles that minimizes exposure to risk factors for hand/wrist injuries. Ten experienced typists (four males and six females) participated in a laboratory study to compare keyboard angles ranging from 0° to ?30°, at 10° increments, and a keyboard with a 7° slope, using a wedge designed for use with standard QWERTY keyboards. Repeatability of exposures was examined by requiring participants to complete two test sessions 1 week apart. Dependent variable data were collected during 10 min basic data entry tasks. Wrist posture data favoured negative keyboard angles of 0° (horizontal) or greater, compared to a positive keyboard angle of 7°, especially for the flexion/extension direction. In general, the percentage of wrist movements within a neutral zone and the percentages of wrist movements within ±5° and ±10° increased as keyboard angle became more negative. Electromyography results were mixed, with some variables supporting negative keyboard angles whilst other results favoured the standard keyboard configuration. Net typing speed supported the ?10° keyboard angle, whilst other negative typing angles were comparable, if not better than, with the standard keyboard. Therefore, angles ranging from 0° to ?30° in general provide significant reductions in exposure to deviated wrist postures and muscle activity and comparable performance.     

Influence of smartphone use styles on typing performance and biomechanical exposure

Twenty-seven subjects completed 2-min typing tasks using four typing styles: right-hand holding/typing (S-thumb) and two-hand typing at three heights (B-low, B-mid and B-high). The styles had significant effects on typing performance, neck and elbow flexion and muscle activities of the right trapezius and several muscles of the right upper limb (p < 0.0001 by repeated-measure analysis of variance). The subjects typed the fewest words (error-adjusted characters per minute: 78) with the S-thumb style. S-thumb style resulted in similar flexion angles of the neck, elbow and wrist, but significantly increased muscle activities in all tested muscles compared with the B-mid style. Holding the phone high or low reduced the flexion angles of the neck and right elbow compared with the B-mid style, but the former styles increased the muscle activity of the right trapezius. Right-hand holding/typing was not a preferable posture due to high muscle activities and slow typing speed.

Practitioner Summary: Right-hand holding/typing was not favoured, due to increased muscle activities and slower typing speed. Holding the phone high or low reduced the flexion angles of the neck and right elbow, but the former styles increased the muscle activity of the right trapezius compared with holding the phone at chest level.     

Shoulder and neck muscle activities during typing with articulating forearm support at different heights

Use of forearm support is known to reduce physical stress of computer users, but research about how to properly position the forearm support is insufficient. This study was aimed to determine whether the height of forearm support influences muscular loads during typing. Twenty four subjects performed a typing task with a pair of articulating forearm support at three different heights as well as without any support, while shoulder, neck and forearm muscle activities and posture data were recorded. Typing with the support at resting elbow height produced significantly (p < 0.05) lower shoulder and neck muscle activities than that of no support condition. Typing with the support at heights higher than the resting elbow height produced significantly greater shoulder and neck muscle activities compared to the no support condition. Results suggest that forearm support can help computer users lessen physical stress in typing, but only when the supports are positioned at resting elbow height.

Practitioner Summary: Use of forearm support is known to alleviate physical stress of PC users in computer works such as typing. This experimental study addressed the importance of proper positioning of forearm support by comparing neck and upper extremity muscle activities between conditions with varying heights of forearm support in keyboard typing.     

Theoretical upper and lower bounds on typing speed using a stylus and a soft keyboard

Abstract

A theoretical model is presented to predict upper-and lower-bound text-entry rates using a stylus to tap on a soft QWERTY keyboard. The model is based on the Hick-Hyman law for choice reaction time, Fitts law for rapid aimed movements, and linguistic tables for the relative frequencies of letter-pairs, or digrams, in common English. The model's importance lies not only in the predictions provided, but in its characterization of text-entry tasks using keyboards. Whereas previous studies only use frequency probabilities of the 26 × 26 digrams in the Roman alphabet, our model accommodates the space har—the most common character in typing tasks. Using a very large linguistic table that decomposes digrams by position-within-words, we established start-of-word (space-letter) and end-of-word (letter-space) probabilities and worked from a 27 × 27 digram table. The model predicts a typing rate of 8.9wpm for novices unfamiliar with the QWERTY keyboard, and 30.1wpm for experts. Comparisons are drawn with empirical studies using a stylus and other forms of text entry.     

Multilingual Touchscreen Keyboard Design and Optimization

A keyboard design, once adopted, tends to have a longlasting and worldwide impact on daily user experience. There is a substantial body of research on touch-screen stylus keyboard optimization. Most of it has focused on English only. Applying rigorous mathematical optimization methods and addressing diacritic character design issues, this article expands this body of work to French, Spanish, German, and Chinese. More important and counter to the intuition that optimization by nature is necessarily specific to each language, this article demonstrates that it is possible to find common layouts that are highly optimized across multiple languages for stylus (or single finger) typing. We first obtained a layout that is highly optimized for both English and French input. We then obtained a layout that is optimized for English, French, Spanish, German, and Chinese pinyin simultaneously, reducing its stylus travel distance to about half of QWERTY's for all of the five languages. In comparison to QWERTY's 3.31, 3.51, 3.7, 3.26, and 3.85 keys of movement for English, French, Spanish, German, and Chinese, respectively, the optimized multilingual layout has an average travel distance of 1.88, 1.86, 1.91, 1.77, and 1.68 keys, correspondingly. Applying Fitts's law with parameters validated by a word tapping experiment, we show that these multilingual keyboards also significantly reduce text input time for multiple languages over the standard QWERTY for experienced users. In comparison to layouts individually optimized for each language, which are also obtained in this article, simultaneously optimizing for multiple languages caused only a minor performance degradation for each language. This surprising result could help to reduce the burden of multilingual users having to switch and learn new layouts for different languages. In addition, we also present and analyze multiple ways of incorporating diacritic characters on multilingual keyboards. Taken together, the present work provides a quantitative foundation for the understanding and designing of multilingual touch-screen keyboards.     

Mathematically modelling the effects of pacing,finger strategies and urgency on numerical typing performance with queuing network model human processor

Numerical typing is an important perceptual-motor task whose performance may vary with different pacing, finger strategies and urgency of situations. Queuing network-model human processor (QN-MHP), a computational architecture, allows performance of perceptual-motor tasks to be modelled mathematically. The current study enhanced QN-MHP with a top-down control mechanism, a close-loop movement control and a finger-related motor control mechanism to account for task interference, endpoint reduction, and force deficit, respectively. The model also incorporated neuromotor noise theory to quantify endpoint variability in typing. The model predictions of typing speed and accuracy were validated with Lin and Wu's (2011) experimental results. The resultant root-mean-squared errors were 3.68% with a correlation of 95.55% for response time, and 35.10% with a correlation of 96.52% for typing accuracy. The model can be applied to provide optimal speech rates for voice synthesis and keyboard designs in different numerical typing situations.

Practitioner Summary: An enhanced QN-MHP model was proposed in the study to mathematically account for the effects of pacing, finger strategies and internalised urgency on numerical typing performance. The model can be used to provide optimal pacing for voice synthesise systems and suggested optimal numerical keyboard designs under urgency.