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Abstract

The aim of this study was to evaluate the effect of sitting and standing on performance and touch characteristics during a digit entry touch screen task in individuals with and without motor-control disabilities. Previously, researchers of touch screen design have not considered the effect of posture (sitting vs. standing) on touch screen performance (accuracy and timing) and touch characteristics (force and impulse). Participants with motor-control disabilities (n = 15) and without (n = 15) completed a four-digit touch screen number entry task in both sitting and standing postures. Button sizes varied from 10 mm to 30 mm (5-mm increments), and button gap was 3 mm or 5 mm. Participants had more misses and took longer to complete the task during standing for smaller button sizes (< 20 mm). At larger button sizes, performance was similar for both sitting and standing. In general, misses, time to complete task, and touch characteristics were increased for standing. Although disability affected performance (misses and timing), similar trends were observed for both groups across posture and button size. Standing affects performance at smaller button sizes (< 20 mm). For participants with and without motor-control disabilities, standing led to greater exerted force and impulse. Along with interface design considerations, environmental conditions should also be considered to improve touch screen accessibility and usability.

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... Freehand interaction with large displays in sitting or standing postures may impose different motor-control demands and physical stress on users, thereby leading to varied interaction performance and perceptions. Several studies have examined the effects of posture on device-assisted interaction with desktop displays (Chourasia et al., 2013;Drury et al., 2008;Hedge et al., 2005;Schedlbauer et al., 2006;Straker et al., 2009). Schedlbauer et al. (2006), for example, found that standing increased error rate in trackball and touchscreen-based interaction for target acquisition. ...
... Schedlbauer et al. (2006), for example, found that standing increased error rate in trackball and touchscreen-based interaction for target acquisition. Chourasia et al. (2013) found that standing resulted in more misses and longer task completion time than sitting in touchscreen-based interaction with smaller target sizes, while both postures produced similar performance with larger target sizes. In contrast, standing was shown to yield fewer errors but similar discomfort compared with sitting in computer-typing tasks (Kar and Hedge, 2016). ...
... Each was answered with a 10-point Likert scale (1 = totally disagree, 10 = totally agree). Perceived workload was assessed with 10-point NASA Task Load Index (NASA-TLX) (Hart and Staveland, 1988), which has been a widely used subjective workload assessment tool in varied human-computer interaction tasks (Chourasia et al., 2013;Tao et al., 2018). ...
Article
The past decade has seen increasing popularity of large display-based freehand interaction. This study examined the effects of body posture, interaction distance and target size on freehand interaction with a large display. Participants performed pointing and dragging tasks by freehand interaction with a large display under sitting and standing postures and at different interaction distances. Targets in both small and large sizes were examined. Results showed that interaction distance yielded a significant effect on error rate, but the effect differed by task type. Little measurable difference was found in interaction performance, perceived usability and workload between sitting and standing postures. There were significant interaction effects between posture and interaction distance on perceived workload. Larger target size led to higher efficiency and accuracy in pointing tasks, but reduced accuracy in dragging tasks. This study provided implications that are likely to improve the design and deployment of large display-based freehand interaction techniques.
... Previous studies have addressed several important design factors for touchscreen interfaces, such as key size and gap between keys [11,[14][15][16][17][18][19]. For example, Pfauth and Priest suggested that key size is one of the most important factors in touchscreen use when the touchscreen interface involved a hierarchical menu display [20]. ...
... Their results indicated that as key size increased, the performance for disable participants improved, while the performance for non-disable group plateaued at a key size of 20 mm. Chourasia et al. evaluated the effect of posture (i.e., sitting and standing) on touchscreen performance and touch characteristics during a digit entry touchscreen task among individuals with and without motorcontrol disabilities [15]. They found that standing affected touchscreen performance only at smaller key sizes (i.e., key sizes smaller than 20 mm) and led to greater exerted force and impulse compared with sitting. ...
... In addition, these studies consistently found that gap size did not affect user performance [11,14,15,19]. However, they did not consider scenarios where there is no gap between keys. ...
... The main reason for the success of touchscreen interfaces is that they allow direct input and are a more intuitive and accessible way to support human-computer interaction [9]. However, users still encounter many problems when using touchscreens, such as finger occlusion and individual variation [10][11][12], and the design characteristics of the interface affect user performance [13][14][15][16]. To solve these limitations, the interface design of smart home control should fully consider factors that may affect the use of the devices. ...
... Other studies considered posture. When the button size was less than 20 mm, the user performance in a standing posture was worse than that when sitting, while there was no significant difference in user performance when the button size was larger [13]. Despite more and more research being published on touchscreen use performance and related standards, studies on touchscreen use in smart home terminal interfaces are still lacking. ...
... The prototype was presented on a Huawei tablet PC with an EMUI 9.1 operating system (8.4 inch screen with a resolution of 2560 × 1600 pixels). Referring to a previous study [13,27], the display screen was at a 70 • angle to the desk surface. Eye movements were sampled using an eye tracker (Tobii Pro Nano, Tobii Tech., Stockholm, The Kingdom of Sweden), with a sampling rate of 60 Hz and a spatial accuracy of 0.3 • or higher. ...
Article
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Touch technology-based smart homes have become increasingly prevalent, as they can help people with independent daily life, especially for the elderly. The aim of this study was to investigate the effects of button features (i.e., button size, graphics/text ratio, and icon style) in smart home interfaces on user performance across two age groups. Participants in the young group (n = 15) and senior group (n = 15) completed a clicking task. Button size ranged from 10 mm to 25 mm with 5 mm increments. The three levels of graphics/text ratio were 3:1, 1:1, and 1:3, while icon style was either flat or skeuomorphic. Results showed that button size and graphics/text ratio had significant effects on user performance in both groups, whereas icon style only had an effect in the senior group. It was observed that the elderly were fond of buttons with a larger size of 20 mm with larger texts and skeuomorphic icons, whereas the young preferred a button size of 15 mm with equal-sized graphics and text. These results may help to improve the accessibility and usability of smart home interface design.
... The literature has documented several factors for touchscreen interface design, among which button size and gap are widely examined [2,3,10,[13][14][15][16][17][18][19][20]. Button size is recognized as the most important factors in touchscreen interfaces. ...
... They found that larger button sizes resulted in improved input performance for disabled participants, while the input performance for healthy participants plateaued when the size of buttons increased. In addition, Chourasia et al. [14] examined the effects of posture on touchscreen performance of digit input tasks in participants with varied motor abilities. Their results indicated that standing posture influenced touchscreen input performance for smaller button sizes only (i.e., button sizes < 20 mm) and resulted in larger impulse force and exerted force in input action compared with sitting posture. ...
... Their results indicated that standing posture influenced touchscreen input performance for smaller button sizes only (i.e., button sizes < 20 mm) and resulted in larger impulse force and exerted force in input action compared with sitting posture. Moreover, these studies consistently reported that button gap exerted no measurable effects on touchscreen input performance [10,13,14,19]. Nevertheless, previous studies failed to examine the effects of absence of gap and compare such scenario with the presence of gap. ...
Chapter
Small, mobile touchscreen devices have increasingly permeated into our daily life over the last decade. However, interface design factors that are likely to influence input performance of the devices have not yet been fully investigated. The purpose of the current study was to explore the effects of keyboard size, gap and button shape on usability metrics in thumb interaction with a small, mobile touchscreen device. Twenty-eight volunteers attended a lab-based experiment where they were required to complete a series of letter input tasks with a touchscreen smartphone. The results indicated that keyboard size yielded significant effects on both accuracy rate and task completion time, and button shape and gap exerted significant influence on task completion time only. Interaction effects were observed between keyboard size and button shape on both accuracy rate and task completion time. Keyboard design factors that exerted optimal input performance were mostly preferred by users. Our findings have important implications and can help with the design of usable touchscreen interface, especially for small, mobile touchscreen devices.
... In an effort toward more usable and accessible touchscreen technology, previous work has studied the layout of user interfaces for touchscreens [10][11][12][13]. In these studies, button sizes and the user's orientation with respect to the touchscreen were studied in order to determine the layouts that are most preferred and have the lowest rate of errors for numerical input. ...
... In these studies, button sizes and the user's orientation with respect to the touchscreen were studied in order to determine the layouts that are most preferred and have the lowest rate of errors for numerical input. Chourasia et al. [11] found that button sizes between 20 9 20 and 30 9 30 mm and a seated position directly facing the screen have the least amount of inaccurate activations. Recently, Kim et al. [14] found that key sizes less than 16 9 16 mm may be too small for touchscreen typing. ...
... Caution needs to be taken in interpreting these previous findings too liberally. Prior touchscreen research has used low mental effort and less ecologically relevant tasks such as reciprocal tapping, crossing targets or number entry [11,12,17,18,29]. In real-world settings, touchscreen use involves mental tasks such as recall or information lookup in addition to the primary task of physically interacting with the touchscreen. ...
Article
Full-text available
The rise in popularity of touchscreens supports the need for improving the usability and accessibility of the technology for users with varying abilities. Touchscreen activation methods (tapping, take-off) can help address these issues but may have trade-offs (longer time to complete task). This study evaluated tapping and take-off touchscreen activation methods during a multi-item selection activity. Participants with (n = 10) and without (n = 10) motor control disabilities affecting upper extremity function (+MCD and −MCD, respectively) completed an experimental task to select four items from a list using either tapping or take-off activation with two different levels of mental effort (memorization vs. no memorization). Fewer errors (29 vs. 21 %, p = .018) but longer task completion times (14.3 vs. 9.04 s, p = .007) were observed for take-off vs. tapping. Error rate doubled for memorization compared to no memorization (33.5 vs. 16.5 %, p = .002). Both +MCD and −MCD groups had fewer errors using the take-off method, but tapping was preferred, had fewer misses and required less task completion time during a menu selection activity. For tablet touchscreen menu selection applications for individuals with and without upper extremity motor control disabilities, take-off activation method is more accurate than tapping though tapping is preferred, has fewer misses and requires less task completion time. Additional mental demand leads to an increase in the number of errors during touchscreen operation.
... The touch characteristics of physical interaction with touch interface have been widely investigated on keyboards and touchscreens in performing tapping tasks (Chourasia, Wiegmann, Chen, Irwin, and Sesto 2013;Irwin, Duff, Skye, Wiegmann, and Sesto 2010;Irwin, Meyer, Yen, Kelso, and Sesto 2008;Irwin and Sesto 2012;Kim, Aulck, Bartha, Harper, and Johnson 2014;Lee et al. 2015;Sesto et al. 2012). Differences in touch characteristics were found between people with and without disabilities, and among people of different gender and age when using touch screens. ...
... Touch characteristics during physical interactions with digital devices are influenced by the design of buttons and the features of the devices themselves. Force increases, whereas dwell time and impulse decrease when performing tapping tasks on touchscreens with the increase in button size (Chourasia et al. 2013;Irwin et al. 2008;Sesto et al. 2012). When using virtual keyboards (i.e. ...
... Less wrist extension is maintained during sitting than during standing when using keyboards (Hedge et al. 2005). Chourasia et al. (2013) found that the exerted force and impulse were larger in standing posture than in sitting posture during tapping tasks on touchscreens. ...
Article
This study aimed to determine the touch characteristics during tapping tasks on membrane touch interface and investigate the effects of posture and gender on touch characteristics variables. One hundred participants tapped digits displayed on a membrane touch interface on sitting and standing positions using all fingers of the dominant hand. Touch characteristics measures included average force, contact area, and dwell time. Across fingers and postures, males exerted larger force and contact area than females, but similar dwell time. Across genders and postures, thumb exerted the largest force and the force of the other four fingers showed no significant difference. The contact area of the thumb was the largest, whereas that of the little finger was the smallest; the dwell time of the thumb was the longest, whereas that of the middle finger was the shortest. Relationships among finger sizes, gender, posture and touch characteristics were proposed. The findings helped direct membrane touch interface design for digital and numerical control products from hardware and software perspectives. Practitioner Summary: This study measured force, contact area, and dwell time in tapping tasks on membrane touch interface and examined effects of gender and posture on force, contact area, and dwell time. The findings will direct membrane touch interface design for digital and numerical control products from hardware and software perspectives.
... Several important design factors, such as button size and spacing between buttons, have been investigated Chourasia et al., 2013;Colle and Hiszem, 2004;Hara et al., 2015;Jin et al., 2007;Kim et al., 2014a, b;Park and Han, 2010;Pitts et al., 2012;Sears, 1991;Sears et al., 1993;Sesto et al., 2012;Xiong et al., 2014). However, evidence on optimal touchscreen design is still mixed, as indicated by varied recommendations from several international standards (e.g., 9.5 mm button size and 3.2 mm gap recommended by ANSI/HFES 100e2007 (Human Factors and Ergonomics Society, 2007), the breadth of distal finger joint dimension from 95th percentile male as minimal button size suggested by ISO 9241-9 (Greiner, 1991), and 19.05 mm button size and 6 mm gap by other standards (Monterey Technologies, 1996)). ...
... Likewise, relationships between these understudied factors and previously widely examined ones (e.g., button size and spacing) have not been well reported, evidence from which might help explain inconsistency in existing design standards and provide more specific design guidelines. In addition, previous studies mostly examined digit input tasks with a simple digit keyboard Chourasia et al., 2013;Colle and Hiszem, 2004). However, a letter keyboard that comprises much more buttons than a digit keyboard is used more often in practice. ...
... For example, Chen et al. (2013) found that user performance from a non-disabled group plateaued at a button size of 20 mm, while performance from a disabled group continued to improve as button size increased. Chourasia et al. (2013) suggested that posture affected user performance in touchscreen number entry tasks. In particular, they found standing yielded worse performance than sitting at smaller button sizes (<20 mm), while both postures produced similar performance at larger button sizes. ...
Article
Touchscreen technology has gained increasing popularity in both personal and public settings. However, button design characteristics that may affect touchscreen use have not been fully investigated. The aim of this study was to examine the effects of button design characteristics (i.e., button size, button spacing, visual feedback and button shape) on users' touchscreen performance, mental workload and preference. Twenty participants participated in an experiment in which they performed both digit and letter input tasks. Button sizes ranged from 7.5 to 27.5 mm with 5-mm increments, while button spacing was absent, 1 mm or 3 mm. Two types of visual feedback (presence and absence) and three button shapes (square, horizontal and vertical rectangles) were examined. Results indicated that button size, button spacing and button shape yielded significant effects on touchscreen performance, while visual feedback had no effect. It is also found that users performed better with medium-to-large size (17.5 mm and larger), square buttons. Mental workload was comparable across button shapes. Users generally preferred button design characteristics that could yield optimal input performance. Relevance to industry: The findings could facilitate the optimal design of usable touchscreen technology.
... Previous studies have addressed several important design factors for touchscreen interfaces, such as key size and gap between keys [11,[14][15][16][17][18][19]. For example, Pfauth and Priest suggested that key size is one of the most important factors in touchscreen use when the touchscreen interface involved a hierarchical menu display [20]. ...
... Their results indicated that as key size increased, the performance for disable participants improved, while the performance for non-disable group plateaued at a key size of 20 mm. Chourasia et al. evaluated the effect of posture (i.e., sitting and standing) on touchscreen performance and touch characteristics during a digit entry touchscreen task among individuals with and without motor-control disabilities [15]. They found that standing affected touchscreen performance only at smaller key sizes (i.e., key sizes smaller than 20 mm) and led to greater exerted force and impulse compared with sitting. ...
... Their results indicated that 19.05 mm size yielded the highest accuracy rate. In addition, these studies consistently found that gap size did not affect user performance [11,14,15,19]. However, they did not consider scenarios where there is no gap between keys. ...
Conference Paper
Touchscreen technology has gained increasing popularity over the last decade in a variety of personal, public and occupational settings. It is of great significance to investigate the effects of interface design factors that may affect the use of the technology. This study was conducted to investigate the effects of key size (ranged from 10 to 25 mm with 5-mm increments), gap (presence and absence) and the location of key characters (upper left, upper right, central, lower left and lower right) on usability metrics (i.e., task completion time, accuracy rate and user preference) in touchscreen input tasks. Fourteen undergraduate students (8 male and 6 female) participated in this study and were required to complete letter input tasks. The results indicated that there was a significant effect of key size on task completion time and accuracy rate, while gap and the location of key characters yielded no measurable effect on user performance. The performance was better for larger key sizes (\( \ge \) 15 mm) than smaller ones. The location of key characters significantly interacted with gap on accuracy rate. Users preferred 15 mm key size, the presence of gap and centrally located key characters. The results may help with the design of more usable and safe touchscreen technology.
... Not only in terms of the interaction effect, the size of the button will also affect the physical health of users by affecting forces, impulses, and dwell times for participants completing tasks on a touch screen (Sesto et al., 2012). However, button function (Park et al., 2020), user posture (Amrish et al., 2013), and screen size (Hancock et al., 2015) all affect the users' demand for button size, and existing studies are unable to provide a reference for the button size design based on the tablet size in a smart home environment. Moreover, most of the existing research targets are press buttons, and there is a lack of research on sliding buttons. ...
... The prototype was presented on a Huawei tablet PC with EMUI 9.1 operating system (8.4 inches size with a resolution of 2,560 × 1,600 pixels). Referring to the previous study (Amrish et al., 2013;Chen et al., 2013), the display screen was at a 70 • angle to the desk surface. Eye movements were sampled using an eye tracker (Tobii Pro Nano), with a sampling rate of 60 Hz and spatial accuracy of 0.3 • or higher. ...
Article
Full-text available
Smart homes represent an effective approach to improve one’s quality of life. Developing user interfaces that are both comfortable and understandable can assist users, particularly the elderly, embrace smart home technologies. It’s critical to concentrate on the characteristics of smart home interface design and their impact on people of various ages. Since sliders are one of the most common components utilized in the smart home user interface, this article aimed to investigate the effects of slider design characteristics (e.g., button size, track color, and sliding orientation) on user performance and preference. Thirty-four participants were recruited for the experiment (16 for the young group, aged between 18 and 44 years; 18 for the middle-aged and elderly group, aged between 45 years and above). Our results revealed that both groups had shorter task completion time, less fixation time, and saccades on horizontal sliding orientation and larger buttons, which means better user performance. For the older group, the slider with color gradient track led to better user performance, while the track color only had less effect on the performance of the younger group. In terms of user preference, the results and performance of the older group were basically consistent, while the younger group had no significant difference in sliding orientation and track color.
... Tao et al. [37] found that a 17.5-mm size is optimal and that a 3-mm gap was better than 0 and 1 mm. No significant effect of gaps was also found [12,13,15,25], but their participants preferred larger gaps (e.g., 6.35 mm in [25]). Note that the term optimal is used in several ways (e.g., for operational time, error rate, and user preference). ...
... In related studies, participants were motivated to quickly and accurately tap a target, while our participants could purposely tap outside the target to avoid tapping distractors, as in realistic touch GUIs. Although it was shown in some studies [12,13,16] that user performance was not significantly affected by gaps, we expect that the CT and error rate will also be affected by gaps due to the penalty. ...
Conference Paper
Full-text available
Targets on touchscreens should be large enough so that they can be tapped by fingers. In addition to the size of a target, properties of unintended targets around the intended target (e.g., margins) could affect user performance. In this study, we investigate the negative effects of such unintended targets (or distractors), which impose a penalty time when tapped for which users have to wait. Our participants sometimes purposely tapped an empty space on the opposite side of the distractor to avoid tapping it, and such behavior was affected by (1) the size of the intended target, (2) gap between the intended target and distractors, and (3) dimensionality of pointing tasks (1D or 2D). We also found that we could not estimate user performance by using Fitts' and FFitts' laws, probably because tap positions tended to shift away from distractors.
... In an empirical study, Page (2013) found that users with no touchscreen experience require longer input time, which may, therefore, make them uncomfortable with touchscreen only devices. Previous studies also found significant influence of gender for touchscreen preference (Weiss et al., 2012) and for touchscreen user performance (Lai and Wu, 2012;Chourasia et al., 2013). Interestingly, touchscreens were preferred by females (Weiss et al., 2012), but their accuracy with touchscreen usage was found to be less than males (Lai and Wu, 2012;Chourasia et al., 2013). ...
... Previous studies also found significant influence of gender for touchscreen preference (Weiss et al., 2012) and for touchscreen user performance (Lai and Wu, 2012;Chourasia et al., 2013). Interestingly, touchscreens were preferred by females (Weiss et al., 2012), but their accuracy with touchscreen usage was found to be less than males (Lai and Wu, 2012;Chourasia et al., 2013). As noted, this study also saw findings that gender had influence on input type preference as did touchscreen experience. ...
Article
Full-text available
One of the major concerns in managing a global organisation is the potential difficulty that could arise due to different cultural preferences for technologies. This study provides evidence that cultural difference can influence ruggedised handheld device design preference. Field workers from different world regions of a worldwide service company responded to a survey expressing their choices on four potential handheld devices, five available features, and on the most influencing feature. The region of the world from which the workers were domiciled was impactful and showed significant influence on device selection as well as on all of the feature preferences.
... are widely used for teaching -learning approaches. Within the current modern life, it can be seen that the touchscreen -based system are used usually as kiosks in order to improve standards in activities in airports, train stations, grocery stores, banks and any other workplaces such as food service, retail and health care fields (Astell et al., 2010;Chourasia et al., 2013;Newman et al., 2012;Schultz et al., 1998;Shervin et al., 2011;Wilson et al., 1995). As being parallel with the expressed points and because of the main objective of this work (designing and developing touchscreen writing / drawing system) and other following objectives; previously performed research studies -works within the subject must also be examined in order to enable readers to have more idea about the work. ...
...  Related to usage of touchscreen -based systems, Chourasia et al. (2013) have provided a work on "evaluating effects of sitting and standing on performance and touch characteristics during a digit entry touchscreen task in individuals with and without motor -control disabilities. The work provides a good evaluation approach for Journal of Multidisciplinary Developments. ...
Article
Full-text available
Developments in information and communication technologies have been greatly influential on the practices in all fields, and education is not an exception to this. To illustrate with, computers were first used in computer – assisted education in order to increase the efficiency of teaching process. Recently, computer has contributed more to the field through interactive and smart class applications that are specially designed for classroom use. The aim of this study is to develop a low – cost, portable and projection – supported touchscreen to be used in educational environments by using FPGA technology and to test its usability. For the purposes of the study, the above mentioned system was developed by using the necessary hardware and software, and later it was tested in terms of usability. This usability test was administered to teachers, who were the target end – users of this touchscreen writing / drawing system. The aim of this test was to determine " user – friendliness " , " subservientness " and " usability " of the system. Several tools were used to obtain data from the users that participated in the study. The analysis and evaluation of the data collected revealed that the system has achieved its objectives successfully.
... An intelligent user interface in which the SSK height and the sizes and locations of texts and buttons adapt to the user's physical characteristics has been proposed (Hagen & Sandnes, 2010) -from the user-centered design perspective, adjustable products that accommodate individual users' unique anthropometric characteristics benefit user experience and health outcomes (Dianat et al., 2018). In addition, some studies have explored the effects of posture (sitting or standing) on touchscreen task performance (Schedlbauer et al., 2006;Chourasia et al., 2013). Chourasia et al. (2013) reported that in general, the frequency of misses and task completion time were higher for standing than sitting, thus suggesting that postural conditions be considered when discussing the accessibility and usability of SSK. ...
... In addition, some studies have explored the effects of posture (sitting or standing) on touchscreen task performance (Schedlbauer et al., 2006;Chourasia et al., 2013). Chourasia et al. (2013) reported that in general, the frequency of misses and task completion time were higher for standing than sitting, thus suggesting that postural conditions be considered when discussing the accessibility and usability of SSK. ...
Preprint
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This study aimed to evaluate the effects of possible physical design features of self-service kiosks (SSK), side and back partitions and chairs, on workload and task performance of older users during a typical SSK task. The study comparatively evaluated eight physical SSK design alternatives, and younger and older participants performed a menu ordering task using each physical design alternative. Older participants showed a large variation in task performance across the design alternatives indicating stronger impacts of the physical design features. In particular, sitting significantly reduced task completion time and workload in multiple dimensions, including time pressure and frustration. In addition, the use of either side or back partitions reduced mean ratings of mental demand and effort. The study suggests placing chairs and either side or back partitions to enhance older adults' user experience. The use of the proposed physical design recommendations would greatly help them use SSK more effectively.
... Es existiert eine Vielzahl von Untersuchungen, die die Eingabe von komplexen Ziffernfolgen auf stationären Touchscreens in Abhängigkeit verschiedener Parameter wie der Position des Nutzers (Chourasia et al. 2013;Colle & Hiszem 2004), der Buttongröße (Schedlbauer 2007) sowie beim Tastaturschreiben auf virtuellen Tastaturen (Sears et al. 1993) analysiert haben. Für die minimale Dauer einer haptischen Rückmeldung bei der Touchscreen-Interaktion bestehen nur Anhaltspunkte. ...
... 18 x 10 mm für einen einzelnen Button (entspricht einer Kassentastatur). Auf der rechten Seite war das größte Tastenfeld mit den Maßen 82 x 110 mm angeordnet, wobei ein Button in Anlehnung an Chourasia et al. (2013) (Oldfield 1971) fünf Linkshänder und 48 Rechtshänder. Die Technikaffinität nach Karrer et al. (2009) zeigt auf einer fünfstufigen Likert-Skala von eins (trifft gar nicht zu) bis fünf (trifft voll zu) in den einzelnen Kategorien jeweils durchschnittlich, eine Technikkompetenz von 3,9 (± 0,7), eine positive Einstellung zu Technik von 3,7 (± 0,4), eine Technikbegeisterung von 3,5 (± 0,7) sowie eine negative Einstellung zu Technik von 2,6 (± 0,6), sodass von einer hohen Technikaffinität der Stichprobe ausgegangen werden kann. ...
Conference Paper
Full-text available
Touchscreens werden zunehmend in alltäglichen Geräten eingesetzt, wobei das Gefühl konventioneller Tasten verloren geht. Eine künstlich generierte haptische Rückmeldung kann nur während der Zeit vermittelt werden, in der ein Finger auf der Touchscreen-Oberfläche verweilt. Mit Hilfe von 53 Versuchsteilnehmern und über 5600 einzelnen Button-Klicks wurde die Berührungsdauer für unterschiedliche Einflussfaktoren von stationären Touchscreens (Neigung, Buttongröße sowie Nutzerposition) ermittelt. Die Ergebnisse zeigen eine durchschnittliche Berührungsdauer von 169 ms sowie eine minimale Berührungsdauer von 80 ms auf einer Touchscreen-Oberfläche. Die Berührungsdauer ist sowohl von der Neigung eines Touchscreens als auch von der Buttongröße abhängig und liefert Erkenntnisse für die Gestaltung einer wahrnehmbaren haptischen Rückmeldung von stationären Touchscreens.
... Regarding gaps between touch-GUI items, Tao et al. [20] found that a 3-mm gap was better than 0 or 1 mm. Interestingly, other studies have found that there is no significant effect of gaps [6,7,8,13]. The objectives of these related studies were to find the optimal size and gap, so they used data for larger touch surfaces (e.g., ATM kiosk terminals) than smart mobile devices. ...
Conference Paper
Full-text available
Optimal target size has been studied for touch-GUI design. In addition, because the degree of risk for tapping unintended targets significantly affects users' strategy, some researchers have investigated the effects of margins (or gaps) between GUI items and the risk level (here, a penalty time) on user performance. From our touch-pointing tasks in grid-arranged icons, we found that a small gap and a long penalty time did not significantly change the task completion time, but they did negatively affect the error rates. As a design implication, we recommend using 1-mm gaps to balance the space occupation and user performance. We also found that we could not estimate user performance by using Fitts' and FFitts' laws, probably because participants had to focus their attention on avoiding distractors while aiming for the target.
... Daily, users will also hold something in one hand and have to answer a call with the other one. When user is sited, his mobile phone use is totally different from a standing use [7]. ...
Conference Paper
This paper introduces the concept of tactile interaction for novice elderly users. Cognitive difficulties, motor constraints, visual overloads and lacks of feedback lead to hardly usable tactile smartphone among elderly users. An optimized tactile interface was produced, offering continuous and secure gestures, and introducing “uncolocated gestures”. Comparative tests to a classic tactile interface show that those gestures solves interaction problems but generates other difficulties. Uncolocation is a solution of interest but has to be learned and has to be progressively acquired through activity. A final enhanced profile for Elderly users was set and solves this situation, enabling uncolocation manipulation for Back and Up-Down commands and preventing it for Validation command, until it is totally acquired by the user.
... Given the findings for accuracy and speed, the use of tilt as opposed to touch for text input is promising -in touch input it has been shown that greater force and greater impulse is needed when standing as opposed to sitting (Chourasia et al. 2013) and so tilt may have an advantage in this space, the other clear reason for its further study is its possibility for blind typing which, as teenagers seek to 'send messages in class while avoiding detection' (see Starner (2004) pg 4) is of interest to this user community. ...
Conference Paper
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Most modern tablet devices and phones include tilt-based sensing but to-date tilt is primarily used either for input with games or for detecting screen orientation. This paper presents the results of an experiment with teenage users to explore a new tilt-based input technique on mobile devices intended for text entry. The experiment considered the independent variables grip (one-handed, two-handed) and mobility (sitting, walking) with 4 conditions. The study involved 52 participants aged 11-16 carrying out multiple target selection tasks in each condition. Performance metrics derived from the data collected during the study revealed interesting quantitative findings, with the optimal condition being sitting using a two-handed grip. While walking, task completion time was 22.1% longer and error rates were 63.9% higher, compared to sitting. Error rate were 31.4% lower using a two-handed grip, compared to a one-handed grip. Qualitative results revealed a highly positive response to target selection performed using the method described here. This paper highlights the potential value of tilt as a technique for text input for teenage users.
... Por otra parte, se han evaluado diversas características técnicas en diversas poblaciones de usuarios. La mayoría de los estudios se han llevado a cabo en sujetos sanos de diversos grupos de edad 8,9 , pero también en personas con discapacidad [10][11][12] . Por ejemplo, la interacción con pantallas táctiles a través de golpeteo con los dedos ha mostrado diferente interacción de los sujetos con enfermedad de Parkinson con respecto a sujetos sanos 13 . ...
Article
Introduction: Smartphones use in biomedical research is becoming more prevalent in different clinical settings. We performed a pilot study to obtain information on smartphone use by patients with essential tremor (ET) and healthy controls, with a view to determining whether performance of touchscreen tasks is different between these groups and describing touchscreen interaction factors. Method: A total of 31 patients with ET and 40 sex- and age-matched healthy controls completed a descriptive questionnaire about the use of smartphones. Participants subsequently interacted with an under-development Android application, and performed 4 tests evaluating typical touchscreen interaction gestures; each test was performed 5 times. Result: The type of smartphone use and touchscreen interaction were not significantly different between patients and controls. Age and frequency of smartphone use are key factors in touchscreen interaction. Conclusion: Our results support the use of smartphone touchscreens for research into ET, although further studies are required.
... According to Schedlbauer et al. (2006) touchscreens are generally well-suited for input tasks while standing, superior to trackballs. However, using touchscreens while standing requires larger interactive elements for the same precision as sitting (Chourasia, Wiegmann, Chen, Irwin, & Sesto, 2013). Ahlström, Lenman, and Marmolin (1992) assessed user fatigue based on screen inclination and showed the positive impact of elbow rests. ...
Thesis
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The goal of this reasearch was to examine if modern touch screen interaction concepts that are established on consumer electronic devices like smartphones can be used in time-critical and safety-critical use cases like for machine control or healthcare appliances. Several prevalent interaction concepts with and without touch gestures and virtual physics were tested experimentally in common use cases to assess their efficiency, error rate and user satisfaction during task completion. Based on the results, design recommendations for list scrolling and horizontal dialog navigation are given.
... 7 Numerous technical characteristics have been evaluated in various user populations; the majority of studies include healthy individuals from a variety of age groups, 8,9 as well as disabled people. [10][11][12] For example, Parkinson's disease has been shown to affect interaction with smartphone screens by tapping. 13 Essential tremor (ET) is one of the most prevalent movement disorders in adults, affecting 5% of people aged over 65. 14 Tremor is affected by posture and limb movements. ...
Article
Full-text available
Introduction Smartphone use in biomedical research is becoming more prevalent in different clinical settings. We performed a pilot study to obtain information on smartphone use by patients with essential tremor (ET) and healthy controls, with a view to determining whether performance of touchscreen tasks is different between these groups and describing touchscreen interaction factors. Method A total of 31 patients with ET and 40 sex- and age-matched healthy controls completed a descriptive questionnaire about the use of smartphones. Participants subsequently interacted with an under-development Android application, and performed 4 tests evaluating typical touchscreen interaction gestures; each test was performed 5 times. Result The type of smartphone use and touchscreen interaction were not significantly different between patients and controls. Age and frequency of smartphone use are key factors in touchscreen interaction. Conclusion Our results support the use of smartphone touchscreens for research into ET, although further studies are required.
... A number of studies have investigated keyboard size [30,33], button size [56], and button spacing [10,12]. All these variables depend on the size of the smartphone. ...
Article
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This study evaluated the effect of gestures (text entry with thumbs of both hands and one-thumb text entry) and smartphone sizes (4.7, 5, and 5.5 inches) on the user experience during text entry with QWERTY and T9 input methods. Messaging using smartphones has become an important communication tool. Users change their gestures depending on the smartphone use context. Many different smartphone sizes are available, but suggestions from an ergonomic perspective are missing. Twenty-four participants used either two-thumb text entry or one-thumb text entry, using both QWERTY and T9. A different group of 24 participants entered text using QWERTY and T9 on smartphones with different sizes. Their performance, subjective rating, and physiological reactions were analyzed. Two-thumb text entry was more effective than one-thumb text entry. Better user experiences were achieved by using QWERTY for two-thumb text entry, by using T9 for one-thumb text entry, and by using QWERTY with a 5-inch smartphone compared with using a 4.7-inch smartphone. Using QWERTY with a 5.5-inch smartphone achieved a higher speed than using a 4.7-inch smartphone. Users who used T9 with a 5-inch smartphone achieved a better user experience than if using a 5.5-inch smartphone. QWERTY is more suitable for two-thumb text entry, while T9 is more suitable for one-thumb text entry. Different smartphone sizes affect the use of input methods. This study provides a reference for smartphone text input interface designers.
Conference Paper
Pinching and spreading gestures are prevalent in mobile applications today, but these gestures have not yet been studied extensively. We conducted an exploratory study of pinch and spread gestures with seated participants on a phone and a tablet device. We found device orientation did not have a significant effect on gesture performance, most pinch and spread tasks were completed in a single action, and they were executed in 0.9-1.2 seconds. We also report how participants chose to sit with the mobile device, variations in gesture execution method, and the effect of varying target width and gesture size. Our task execution times for different gesture distances and precision levels display a surprisingly good fit to a simple Fitts's Law model. We conclude with recommendations for future studies.
Conference Paper
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Several studies investigated different interaction techniques and input devices for older adults using touchscreen. This literature review analyses the population involved, the kind of tasks that were executed, the apparatus, the input techniques, the provided feedback, the collected data and author's findings and their recommendations. As conclusion, this review shows that age-related changes, previous experience with technologies, characteristics of handheld devices and use situations need to be studied.
Article
Sitting in a parallel orientation in front of a touch screen (requiring twisting of the torso) was found to cause a decrement in touchscreen performance (36%–48%). However, the adverse effect of sitting orientation on performance could be ameliorated by interface design, most notably by using button sizes greater than 20×20 mm. Larger button sizes also benefit individuals with upper extremity motor control disabilities, and this information could be used to incorporate universal design in touchscreen interfaces. Larger button sizes also help in reducing the force-time integral during button activation. Touchscreens are widely used in occupational settings, such as retail, restaurants, and health care. The touchscreen performance findings from this study are applicable to touchscreen interface design for users with and without upper extremity motor control disabilities, and the touch characteristics findings are useful for ergonomists quantifying forces involved in touchscreen operation.TECHNICAL ABSTRACT Background: Touchscreens can be used in stand-alone kiosks, embedded in larger structures, such as walls, or arranged in multi-display configurations (e.g., a control station). As a result, users may not always be positioned in front of the screen and may instead operate it in a variety of orientations. Previous touchscreen research has not considered the effect of user sitting orientation on touchscreen performance, such as in terms of the number of errors (incorrect button activation), misses (touch that does not result in button activation), task completion time, and touch characteristics (e.g., force, dwell time [the time the button was pressed], and force-time integral). Purpose: This study evaluates the effect of sitting orientation on performance and touch characteristics during a digit entry task among individuals with and without motor control disabilities, including wheelchair users and non-users. Methods: Participants with (n = 21) and without (n = 21) upper extremity motor control disabilities (+MCD and −MCD, respectively) completed a four-digit entry task on a touchscreen in both front and parallel orientations to the touchscreen. Button sizes of 10×10 to 30×30 mm (5-mm increments) and two button gaps (3 or 5 mm) were used. Results: Accuracy was adversely affected, with errors (36%) and misses (48%) greater in the parallel orientation. Dwell time (12%) and force-time integral (21%) were also greater in the parallel orientation than in the front orientation. Larger button sizes (≥20 mm) lowered misses, errors, force-time integrals, and dwell times for both orientations. The +MCD group had a greater percentage of trials with misses (150%) and longer dwell times (66%) than the −MCD group, but in general, similar trends in performance and touch characteristics were observed for both groups across button sizes, button gaps, and sitting orientation. Conclusions: Decrements in touchscreen performance occurred in the parallel orientation compared to the front orientation. In addition, greater forces were exerted and greater workload was reported in the parallel orientation than in the front orientation. However, performance may be improved by using larger button sizes (≥20×20 mm). This may be especially important in critical touchscreen activities.
Article
As the number of touchscreen displays begin to proliferate in work settings the need for display placement recommendations based on sound practices and good science rises. While studies have reported on touch display placement and resulting postures and discomfort for seated computer users, investigation into the adjustment requirements for standing workers using a touchscreen display and keyboard are limited, and focus primarily on handheld units. This poster describes a methodology combining existing research and anthropometric modeling to develop a recommended range of touchscreen placement suitable for standing computer users who also need to interface with a keyboard.
Article
As the use of touch screen technology increases in everyday situations for all walks of life, universal design should be taken into account when designing products to be used by a wide range of users. This re-search studies the workload associated with touch screen use from a front and parallel orientation for individuals with and without motor control disabilities. The NASA Task Load Index (NASA-TLX) was used to assess workload. Participants with a motor control disability (+MCD; n=20) and age-matched participants without a motor control disability (-MCD; n=18) completed a four-digit touchscreen number entry task. Results show that the +MCD group had a higher perceived workload than the –MCD group. The workload demands of the parallel vs. front orientation were higher for both groups across most TLX subscales. The magnitude of the difference in workload between parallel and front orientation was greater for the +MCD group. The results from this study suggest that when the parallel orientation is necessary, careful consideration should be given to designing touch screen interfaces to reduce workload for all users.
Article
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We examined the usability issues associated with four touch screen gestures (clicking, dragging, zooming, and rotating) among older and younger users. It is especially important to accommodate older users' characteristics to ensure the accessibility of information and services that are important to their quality of life. Forty older and 40 younger participants completed four experiments, each of which focused on one gesture. The effects of age, type of touch screen (surface acoustic wave vs. optical), inclination angle (30°, 45°, 60°, and 75°), and user interface factors (clicking: button size and spacing; dragging: dragging direction and distance; zooming: design of zooming gesture; rotating: design of rotating gesture) on user performance and satisfaction were examined. Button sizes that are larger than 15.9 × 9.0 mm led to better performance and higher satisfaction. The effect of spacing was significant only when the button size was notably small or large. Rightward and downward dragging were preferred to leftward and upward dragging, respectively. The younger participants favored direct manipulation gestures using multiple fingers, whereas the older participants preferred the click-to design. The older participants working with large inclination angles of 60° to 75° reported a higher level of satisfaction than the older participants working with smaller angles. We proposed a set of design guidelines for touch screen user interfaces and discussed implications for the selection of appropriate technology and the configuration of the workspace. The implications are useful for the design of large touch screen applications, such as desktop computers, information kiosks, and health care support systems. © 2015, Human Factors and Ergonomics Society.
Article
Tablet computers have become ubiquitous. There is a serious risk that using tablets may lead to musculoskeletal disorders. This research aims to investigate, for tablet computer users, the musculature load and comfort perception of the engaged upper extremity for three angles of viewing and common task types performed at a computer workstation. Thirty healthy adults were recruited. A 3 × 2 repeated experimental design with tilt angle (22.5°, 45°, and 67.5° from horizontal) and task type (movie watching vs. game playing) was employed. The muscular activity of the upper extremity was assessed by electromyography measurement. Subjective comfort ratings were collected using the visual analogue scale. The results showed that when tablets were mounted at a high tilt angle (67.5°), neck muscle activity was low; however, when the tablet computer was mounted at a low tilt angle (22.5°), shoulder forward flexion activity was low, particularly during the game-playing task. This article suggests that users who feel musculoskeletal discomfort in the neck area increase the angle of their tablet computers to decrease neck stress and that users who have musculoskeletal discomfort in the shoulder area position the tablet computer at a lower tilt angle to decrease shoulder stress.
Article
Background and objective As cognitive, motor, and sensory skills decline with age, the interface needs of elderly users differ from that of young adults, especially when entering important information in healthcare applications (e.g. blood glucose values) via a numeric keypad on a smartphone touchscreen. The aim of this study is to propose an optimal numeric keypad design for elderly users. A total of 51 participants greater than or equal to 65 years old completed a 6-digit numeric entry task on a smartphone touchscreen. The Java-based experimental program allows participants to operate 45 different keypad designs consisting of three button shapes (circle, vertical rectangle, and square), five button sizes with 2.5-mm increments (7.5 mm, 10 mm, 12.5 mm, 15 mm, and 17.5 mm), and three button spacings (0 mm, 1 mm, and 3 mm). The usability of the keypad design was compared based on task completion time, error rate, and subjective satisfaction, while the data was analyzed using repeated measures ANOVA. The results show that circle and square buttons outperform the vertical rectangle button in completion time, accuracy, and satisfaction. Square and circle buttons in 15 mm size led to improved efficiency and decreased error rate. Moreover, task completion time for 3 mm is significantly shorter than 0 mm spacing. Given sufficient space on the touchscreen, the 3 mm spacing can be considered optimal when designing a numeric keypad interface. This study presents a comparison of different numeric keypad designs and the impact on the performance and satisfaction of elderly users. The result can be applied to smartphone numeric keypad design to increase input accuracy and speed. In addition, both circle and square buttons can be adopted in user interfaces for elderly users without the decline of usability. Relevance to industry The proposed configuration of button shape, size, and spacing can be applied to the numeric keypad user interface (UI) of smartphones targeting elderly users, especially in healthcare applications.
Chapter
This study examined gesture preferences for a vertical or horizontally-oriented multi-touch input device. Gesture interfaces have become prevalent, increasing the need to characterize technology expectations. The current study expanded previous work (Morris in Proceedings of graphics interface, 2010), which identified preference of a gesture for a given command. Forty employees from Space and Naval Warfare Systems Center Atlantic participated. Twenty-one participants were tested with a vertical multi-touch device while 19 were tested with a horizontal multi-touch device. For a subset of commands (duplicate, enlarge, rotate), orientation was a factor in gesture preference. A subset of gestures was preferred with a vertical orientation and another subset preferred with a horizontal orientation. Users indicated that gestures were relatively easier in the vertical orientation compared to horizontal. Orientation should be considered when designing command gestures for multi-touch devices. Potential applications of this research include design of gesture commands for future multi-touch systems.
Chapter
This study investigates the relationship between both-hand input area and time delay before effective inputs, the relationship between button size and hit accuracy, as well as the influence of button size on users’ perception of the ease of button touching despite the size of the touchable area. The lower-left-hand area with x coordinates between 28 mm to 36 mm is the optimal input area for left the hand and the lower-right-hand area with x coordinates between 30 mm to 40 mm is the most ideal input area for the right hand. The input area with a time delay of 400 ms on the right is slightly larger than the one on the left. When the button with a diameter of 9 mm is placed in the lower-right-hand corner with a x coordinate between 20 mm–50 mm, we can expect a hit rate of 90%. Users’ perception of how easy a button is to touch is mainly related to the button size instead of the size of the touchable area. These findings provide a reference for designing buttons in landscape-orientation MMO mobile games and quantitative suggestions for the sizes of touch input area and button in landscape-orientation MMO mobile games. Based on these insights, game producers and designers can create better user experience for MMO mobile games’ battle interface.
Book
This book focuses on emerging issues in ergonomics, with a special emphasis on modeling, usability engineering, human computer interaction and innovative design concepts. It presents advanced theories in human factors, cutting-edge applications aimed at understanding and improving human interaction with products and systems, and discusses important usability issues. The book covers a wealth of topics, including devices and user interfaces, virtual reality and digital environments, user and product evaluation, and limits and capabilities of special populations, particularly the elderly population. It presents both new research methods and user-centered evaluation approaches. Based on the AHFE 2016 International Conference on Ergonomics Modeling, Usability and Special Populations, held on July 27-31, 2016, in Walt Disney World®, Florida, USA, the book addresses professionals, researchers, and students dealing with visual and haptic interfaces, user-centered design, and design for special populations, particularly the elderly.
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Screen mirroring might be a way to improve older adults’ user experience of smart televisions (STVs) through smartphones. To examine this possibility, two experiments were conducted. Experiment I examined older adults’ difficulties of screen mirroring (mirroring smartphone screens to STVs) through five common touch gestures (“Drag,” “Slide,” “Zoom,” “Draw,” and “Handwrite”), in comparison to younger adults. The results indicated that a major problem for older adults is the frequent attention switching between the STV and smartphone screens. Therefore, experiment II explored how to reduce the need of attention switching through the touch gestures (“Tap,” “Slide + Tap,” and “Slide + Release”) and the button sizes (8, 14, and 20 mm) for different input postures. Thirty older adults participated in this experiment and their eye movements were tracked. Four major findings were derived. First, the “Zoom,” “Draw,” and “Handwrite” gestures in screen mirroring were difficult for older adults with a task completion rate lower than 68%. Second, the problem of frequent attention switching between the STV and smartphone was predominant for tapping tasks. Third, the “Slide + Tap” and “Slide + Release” touch gestures helped to reduce attention switching in tapping tasks more than the “Tap” for older adults, while the “Slide + Release” received the worst subjective feedback. Fourth, increasing the button size from 8 mm to 14 mm on smartphones can improve the task completion rate and the task efficiency in screen mirroring when older adults used the one-handed posture to tap.
Article
Although many studies have been conducted on the human factors and ergonomics (HFE) of touchscreens, no comprehensive review has summarized the findings of these studies. Based on a schema (three dimensions of understanding critical for successful display selection) presented by Wickens et al. (2004), we identified three dimensions of analysis for touchscreen implementations: touchscreen technology, setting and environment of implementation, and user population. We conducted a systematic review based on the PRISMA protocol (Moher et al., 2009), searching five article databases for relevant quantitative literature on touchscreens. We found that all three dimensions of analysis have a significant effect on the HFE of touchscreens, and that a selection for or against touchscreens must take into consideration the specific context of system interaction in order to maximize safety, performance, and user satisfaction. Our report concludes with a set of specific recommendations for systems designers considering touchscreens as input/output devices, and suggestions for future study into the HFE of touchscreens.
Article
Touchscreen has gained increasing popularity. However, little is known about touchscreen use in vibration environments. This study aimed to examine the effects of control-to-display gain (GAIN) and operation precision requirement on touchscreen operations in varied vibration environments. Twenty participants attended an experiment where they were instructed to perform three types of basic touchscreen operation tasks in static, low vibration, and high vibration environments, respectively. Five GAINs (0.75, 1, 2, 3 and 4) and three operation precision requirements (90%, 95%, and 99%) were examined. The results indicated that vibration exerted adverse effects on task performance, and increased perceived workload, perceived task difficulty and discomfort. Task completion time showed a U-shaped curve as GAIN increased. Lowering operation precision requirement improved task performance and reduced perceived workload, especially in vibration environments and at larger GAINs. The findings provide practical implications on the design of usable touchscreen interfaces in vibration environments.
Article
Visual search is one type of common encountered human-computer interaction tasks, but it has less been examined in vibration environments. The aim of this study was to examine the effects of one user characteristic (spatial ability) and two stimulus characteristics (i.e., stimulus size and stimulus density) on visual search performance during single- and double-target tasks in simulated vibration environments. Twenty-four participants attended an experiment where they were instructed to perform single- and double-target visual search tasks with varied levels of stimulus size and stimulus density under static, slight and moderate vibration environments, respectively. Results indicated that the two vibration conditions achieved comparable visual search performance, perceived visual fatigue, and perceived comfort with static condition across task types. Stimuli size and stimulus density yielded significant effects on visual search time in both single- and double-target tasks (p's < 0.001). Participants with high spatial ability were faster than those with low spatial ability in double-target tasks (p = 0.042). Users preferred interface design with medium-to-large stimulus size and low-to-medium stimulus density in visual search.
Article
The aim of this study was to propose a new method for optimizing the touch-screen installation position in order to minimize the physical workload and increase screen visibility. Ten students participated in this study. The participants utilized a touch screen at different installation heights (50, 65, and 80% of stature), tilt angles (0°, 45°, and 90° from the horizontal plane), and having different button sizes (a square with a side of 10, 20, and 30 mm). The joint angles, when using a touch screen, were measured to calculate the joint torque ratios (JTRs). Subjective screen visibility were also determined. The optimal installation position was determined by solving a bi-objective optimization problem consisting of two objective functions. The Pareto optimal solutions for the two objectives showed a range of 1124-1251 mm and 44.4-67.9°. The proposed method determined the optimal installation position of the touch screens.
Chapter
Our active lifestyles see us playing, pausing, and skipping through life all the while our phones are in our hands. For many, completing the daily grind requires regular audio and visual media accompaniment and for this we interact with our phones as we skip, run, and jump. In this respect, a unique form of digital library is our mobile media player of choice. These media players serve as both the interface for listening to and watching these audio and visual media as well as the media library and storage. We argue therefore that the interface design considerations of the media library as well as the media interaction require user centered investigation. We tested button placement variations and analyzed the user preferences as well as user interaction with these mobile media player prototypes while on the move. Early insights suggest users prefer what they are most accustomed to, yet issues of accuracy with interface designs that are unfamiliar require further investigation.
Chapter
To examine the effects of button size with different shape on the usability of touch screen devices. Considering the forefinger operation, the subjective and objective evaluation were combined to assess the ergonomics of the touch-sensitive button size, so as to obtain the recommended range of button size. With the size of touch-sensitive buttons specified setting from 3 mm to 25 mm respectively, where the step size was 2 mm, thirsty subjects participated in the test. One-way ANOVA was used to analyze the operational performance (reaction time and error rate) at different key sizes, and then the S-N-K-hoc multiple pairwise comparison test was used for pairwise comparison. The results demonstrated that the recommended range for rounded corner touch button is from 11 mm to 19 mm, round touch button in the recommended range is from 13 to 19 mm. It is also confirmed that the rounded corner touch buttons are superior to round touch buttons in the same size. This research can provide a basis for the design of button size of enterprise electronic products, and has important guiding significance.
Article
Background/objective: This study aimed to investigate performance (touch-coordinate errors, inter-touch interval) of touch screen technology in adolescents with unilateral spastic cerebral palsy (USCP) and healthy peers. Materials and methods: This prospective case-control study included 31 adolescents. The participants consisted of 15 adolescents with CP in the USCP group and 16 age-matched healthy peers in the control group. All participants performed an aiming-tapping task with an Android tablet. Four sessions were randomly applied: visual feedback (VF) and no VF with the dominant hand's index finger (DHF), and VF and no VF with the non-dominant hand's index finger (NDHF). Inter-touch interval (ITI) and touch-coordinate errors (TCE) were calculated. Results: There were significant differences between the groups for VF and no VF-NDHF TCE and ITI (respectively p= 0.001, p= 0.01, p= 0.001, p= 0.004) and VF and no VF-DHF TCE values (respectively p= 0.01, p= 0.008). When comparing the dominant and non-dominant hand in the USCP group, there was a significant difference on TCE with no VF (p= 0.01). Conclusion: This study provided insight into the touch screen performance of adolescents with USCP, who performed an aiming-tapping task with a tablet. Results showed that both affected and unaffected hand performance of touch screen tasks was impaired in adolescents with USCP.
Article
This study aimed to examine the effects of body posture, typing style and device type on upper limb and shoulder muscle activities, typing performance and perceived workload while typing with mobile devices. Participants were asked to type with two mobile devices (i.e., a tablet and a smartphone) under three postures and in two typing styles. Muscle activity was recorded for four upper limb and shoulder muscles on both sides with surface electromyography. Results showed that body posture and typing style yielded significant effects on tying performance, perceived workload, and muscle activities in the forearm, upper arm and shoulder. Typing with a tablet was more accurate and had greater muscle activities in the upper arm and forearm on both sides than typing with a smartphone. The findings may be useful in developing evidence-based guidelines for the wise use of mobile devices and for the prevention of risks for musculoskeletal disorders.
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While developing touch-screen displays for the food-service industry, the need for adjustability was investigated. Although there are many guidelines for the design and placement of monitors and keyboards in the office environment, there are few such guidelines for touch-screen displays in common service areas. In order to determine the optimal viewing angle or range for a given touch-screen display, an anthropometric/workstation analysis and a user study were conducted. The anthropometric/workstation analysis used a worldwide range (2.5th percentile Japanese female to 97.5th percentile United States male) of user heights for consideration in several scenario drawings. The user study measured the preferred touch-screen display viewing angles (at a standing position) of 26 participants whose stature ranged from 152.4 cm (5 ft) to 194.3 cm (6 ft 4.5 in). The results of the anthropometric/work-station analysis showed a recommended range of 30° to 55° off the horizontal, whereas the results of the study showed that the participants adjusted the touch-screen between the angles of 19° and 54.5° off the horizontal. The outcome of the analysis and study gave reason to conclude that there is no optimal viewing angle for touch-screen displays in a food-service environment with a dynamic set of user heights and a static workstation height. The displays should be adjustable through a range that accommodates multiple users and work-stations, and provides adjustment to compensate for other miscellaneous variables such as glare.Relevance to industryComputer-based consumer interactions are becoming increasingly common. Effective interactions are crucial to commercial success and aspects such as vision and control are likely to be important determinants.
Conference Paper
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This study investigated the optimal button size and spacing for touch screen user interfaces intended for use by older adults. Current recommendations in the literature are aimed at general audiences and fail to consider the specific needs of older adults. Three independent variables, button size, button spacing, and manual dexterity were studied in two experiments that measured reaction time, accuracy and user preferences. Design recommendations for touch screen button size and spacing for older adults are stated based on these experiments. The paper also discusses the role of manual dexterity in designing appropriate touch screen interfaces for older adults.
Conference Paper
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Computing devices are becoming more ubiquitous and are increasingly being used in unconventional environments and body postures. For example, more commonly computers are being used while standing up or walking slowly, such as with bank teller machines or hand-held devices. This paper investigates the effect of posture on Fitts' law and cursor position time in user interfaces when using a touch screen or trackball as the input device. Several experiments are described that measure the effect of standing and walking slowly during the interaction. Fitts' law was found to be an effective predictor of movement time across various targets sizes. Standing and walking did not have a significant negative effect on movement time when using a stylus, although a significant increase in error rate was discovered. However, when using a trackball in a standing posture, movement time and error rate both showed a significant increase. Based on these findings, touch screens appear to be more effective input devices for interactive systems that are used in non-sitting postures
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Progressive and irreversible cognitive impairments affect the ability of people with dementia to communicate and interact with caregivers. This places a burden on caregivers to initiate and manage interactions to the extent that they may avoid all but essential communication. CIRCA is an interactive, multimedia touch screen system that contains a wide range of stimuli to prompt reminiscing. The intention is that people with dementia and caregivers will explore CIRCA together, using the recollections sparked by the media as the basis for conversations. This paper reports an evaluation of the utility of CIRCA looking particularly at whether CIRCA can meet the needs of both people with dementia and caregivers to engage in mutually satisfying interactions. The findings confirm that people with dementia can use the touch screen system and that the contents prompt them to reminisce. The system also supports caregivers to interact with people with dementia as more equal participants in the conversation. The results suggest that interacting with the touch screen system is engaging and enjoyable for people with dementia and caregivers alike and provides a supportive interaction environment that positively benefits their relationships.
Conference Paper
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In this paper, we present a field study comparing software-based navigation techniques (scrollbars, tap-and-drag, and touch-n-go) on mobile devices. In particular, we were interested in exploring the efficiency and user preference of these navigation techniques for different levels of mobility (sitting, walking, and standing) in a naturalistic environment. Results show that while there was no significant difference in performance between tap-and-drag and touch-n-go, both techniques significantly outperformed scrollbars for simple, multi-directional navigation tasks. In addition, the users preferred the touch-n-go technique over the other two methods. The results also revealed that users' interactions and preferences differed between the levels of mobility.
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Touch screens are becoming ubiquitous technology, allowing for enhanced speed and convenience of user interfaces. To date, the majority of touch screen usability studies have focused on timing and accuracy of young, healthy individuals. This information alone may not be sufficient to improve accessibility and usability of touch screens. Kinetic data (e.g. force, impulse, and direction) may provide valuable information regarding human performance during touch screen use. Since kinetic information cannot be measured with a touch screen alone, touch screen-force plate instrumentation, software, and methodology were developed. Individuals with motor control disabilities (Cerebral Palsy and Multiple Sclerosis), as well as gender- and age-matched non-disabled participants, completed a pilot reciprocal tapping task to evaluate the validity of this new instrumentation to quantify touch characteristics. Results indicate that the instrumentation was able to successfully evaluate performance and kinetic characteristics. The kinetic information measured by the new instrumentation provides important insight into touch characteristics which may lead to improved usability and accessibility of touch screens.
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Touch screen input keys compete with other information for limited screen space. The present study estimated the smallest key size that would not degrade performance or user satisfaction. Twenty participants used finger touches to enter one, four or 10 digits in a numeric keypad displayed on a capacitive touch screen, while standing in front of a touch screen kiosk. Key size (10, 15, 20, 25 mm square) and edge-to-edge key spacing (1, 3 mm) were factorially combined. Performance was evaluated with response time and errors, and user preferences were obtained. Spacing had no measurable effects. Entry times were longer and errors were higher for smaller key sizes, but no significant differences were found between key sizes of 20 and 25 mm. Participants also preferred 20 mm keys to smaller keys, and they were indifferent between 20 and 25 mm keys. Therefore, a key size of 20 mm was found to be sufficiently large for land-on key entry.
Article
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An experiment was conducted to investigate the effect of key stiffness on the development of fatigue, keyboard reaction forces, and muscle electromyography (EMG) responses. Six subjects typed continuously for 2 hours on each of two keyboards (0.28 N or 0.83 N resistance keys, presented in random order). Keyboard reaction force and root mean square finger flexor and extensor EMG were recorded for 2 minutes at 250 Hz for every 10 minutes subjects typed. After typing for 2 hours subjects were given a 2-hour rest break and then typed on the remaining keyboard for an additional 2 hours Fifty-four percent more peak force, 34% more peak finger flexor EMG, and 2% more peak finger extensor EMG were exerted while using the 0.83 N keyboard. Peak and 90th percentile values showed similar trends and were well correlated for force and finger flexor and extensor EMG. Subjects typed much harder than necessary (4.1 to 7.0 times harder on the 0.28 N keyboard and 2.2 to 3.5 times harder on the 0.83 N keyboard) to activate the keys. Fatigue was observed on the 0.83 N keyboard during 2 hours of continuous typing, but the trends were mild. It appears that the ratio of typing force to flexor EMG may not be a sensitive enough indicator of fatigue for low-force high repetition work.
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This study investigates the effects of key switch design parameters on short-term localized muscle fatigue in the forearm and hand. An experimental apparatus was utilized for simulating and controlling key switch make force and travel using leaf spring mechanisms, and provided direct measurement of applied key strike force using strain gauge load cells. Repetitive key tapping was performed as fast as possible using the dominant index finger for 500 s per condition (8.3 min) and a work-rest schedule consisting of 15 s of key tapping alternating with 10 s of rest. One combination of two make force levels (0.31 and 0.71 N) and two over travel distances (0.5 and 4.5 mm) was presented randomly on four different days. Nine subjects participated. Localized muscle fatigue in the hand and forearm was assessed subjectively using a 10 cm visual analogue scale, and objectively using surface electromyography (EMG). Average peak key strike force exerted was 0.35 N less for the smaller make force and 0.59 N less for the longer over travel distance. Fatigue occurred in all cases but no significant differences were observed between key switch parameters based on RMS EMG. Subjective reports of localized fatigue after 500 s were less when the key switch make force was less; however, a corresponding over travel effect was not observed despite the greatly reduced key strike force for the longer over travel distance. This discrepancy may be explained by the greater finger movement that was observed with increased over travel. Although there was no apparent improvement in short-term discomfort from fatigue when over travel was increased, this study did not consider the potential long-term health benefits from reduced key strike force.
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The effects of keyswitch stiffness and key action on typing force, electromyography (EMG), and subjective preference were examined. Each subject's own keyboard (with an audible key click and key activation force of 0.72 N) and three keyboards with no key click that were identical in design but had different key activation forces (0.28 N, 0.56 N, and 0.83 N) were used. Subjects (24 female transcriptionists) typed on each keyboard for 15 min while typing force and left hand surface EMG of the finger flexor and extensor muscles were monitored. Subjects then used one of the keyboards at their workstations for 7 workdays and were monitored again. This procedure was repeated for all four keyboards. Typing force and finger flexor and extensor EMG activity were highest for the 0.83 N keyboard. Lowest EMG values were for the 0.28 N and the 0.72 N audible key click keyboards. Baseline (10th percentile) and median (50th percentile) extensor EMG values were significantly higher than flexor EMG values. Peak (90th percentile) EMG values were comparable for flexors and extensors. Mean subjective discomfort was significantly higher for the 0.83 N keyboard at the fingers (36% higher), lower arm (40% higher), and overall (39% higher). Seventeen of 24 subjects preferred the 0.72 N keyboard, 4 the 0.28 N keyboard, and 3 preferred the 0.56 N keyboard. Results suggest that increasing make force causes typing force and EMG to increase but that the ratio of 90th centile typing force to make force decreases as make force increases. Subjective discomfort was significantly higher for the keyboard with 0.83 N make force. Buckling spring keyboards have better feedback characteristics, which may be responsible for a decrease in the amount of typing force and EMG produced.
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Work-related musculoskeletal disorders (WMSDs) in the neck/shoulder region and the upper extremities are a common problem among computer workers. Occurrences of motor unit (MU) double discharges with very short inter-firing intervals (doublets) have been hypothesised as a potential additional risk for overuse of already exhausted fibres during long-term stereotyped activity. Doublets are reported to be present during double-click mouse work tasks. A few comparative studies have been carried out on overall muscle activities for short-term tasks with single types of actions, but none on occurrences of doublets during double versus single clicks. The main purpose of this study was to compare muscle activity levels of single and double mouse clicks during a long-term combined mouse/keyboard work task. Four muscles were studied: left and right upper trapezius, right extensor digitorum communis (EDC) and right flexor carpi ulnaris. Additionally, MU activity was analysed through intramuscular electromyography in the EDC muscle for a selection of subjects. The results indicate that double clicking produces neither higher median or 90th percentile levels in the trapezius and EDC muscles, nor a higher disposition for MU doublets, than does single clicking. Especially for the 90th percentile levels, the indications are rather the opposite (in the EDC significantly higher during single clicks in 8 of 11 subjects, P < 0.05). Although it cannot be concluded from the present study that double clicks are harmless, there were no signs that double clicks during computer work generally constitute a larger risk factor for WMSDs than do single clicks.
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In order to determine differences in biomechanical risk factors across computer tasks, a repeated measures laboratory experiment was completed with 30 touch-typing adults (15 females and 15 males). The participants completed five different computer tasks: typing text, completing an html-based form with text fields, editing text within a document, sorting and resizing objects in a graphics task and browsing and navigating a series of intranet web pages. Electrogoniometers and inclinometers measured wrist and upper arm postures, surface electromyography measured muscle activity of four forearm muscles and three shoulder muscles and a force platform under the keyboard and force-sensing computer mouse measured applied forces. Keyboard-intensive tasks were associated with less neutral wrist postures, larger wrist velocities and accelerations and larger dynamic forearm muscle activity. Mouse-intensive tasks (graphics and intranet web page browsing) were associated with less neutral shoulder postures and less variability in forearm muscle activity. Tasks containing a mixture of mouse and keyboard use (form completion and text editing) were associated with higher shoulder muscle activity, larger range of motion and larger velocities and accelerations of the upper arm. Comparing different types of computer work demonstrates that mouse use is prevalent in most computer tasks and is associated with more constrained and non-neutral postures of the wrist and shoulder compared to keyboarding.
The effects of using an electric height-adjustable worksurface, with and without the addition of a negative-tilt keyboard tray, on wrist posture, comfort, typing performance and body movements was studied. Eighteen subjects experienced four test conditions: typing while sitting with the keyboard on a flat surface or negative tilt keyboard tray, and standing with the keyboard on a flat surface or negative tilt keyboard tray. Results show that the most neutral typing wrist posture (least wrist extension) was maintained when sitting rather than standing. There was a slight wrist posture benefit with the negative tilt tray for both sitting and standing. Sitting with a negative-tilt tray was the most comfortable condition. Sitting was more comfortable than standing. No performance differences between conditions were found. When sitting there was more foot movement than when standing. When standing there was more weight shifting than when sitting.
People are increasingly required to interact with touch screens at places ranging from grocery stores to airport kiosks. To date, most of the usability research related to touch screens has included young, healthy subjects. Using novel instrumentation consisting of a force plate and a touch screen, a number entry study examined finger-touch screen interaction by participants with Cerebral Palsy, Multiple Sclerosis, and non-disabled controls. Timing data as well as peak forces and impulses in three dimensions were collected for each touch. The results indicate that, although average peak force vector magnitudes, impulses, and dwell times are similar between the groups, there are significant differences within the same three variables by button size. Average peak force vector magnitude increased by 11 percent while the average vector impulse decreased by 29 percent from the smallest to the largest button size. The average dwell time also decreased 23 percent from the smallest to the largest button size.
As touch screen technology improves in functionality and decreases in price, these input devices are becoming increasingly more integrated into daily life. People are frequently required to interact with touch screens at places ranging from their local grocery stores to airport check-in kiosks. Since it is becoming necessary for people to use touch screens in order to access needed products or services, we conducted an experiment to examine how individuals with varying motor control disabilities perform on a simple number entry task. Since some individuals may also be wheelchair users, and the Americans with Disabilities Act Accessibility Guidelines allows for the touch screen to be approachable by a wheelchair user from the front or parallel (side), the effect of approach on performance was also evaluated. Participants with and without motor control disabilities, including wheelchair users, performed a number entry task on a number pad with different combinations of button and gap sizes, while seated at a touch screen kiosk. Results revealed that participants with motor control impairments had significantly more inaccurate touches overall than participants without. Performance from the front orientation was significantly more accurate than from the side for all participants, regardless of the presence of a motor control disability. Results from this study may be used to guide design of touch screen accessibility for individuals with motor control disabilities and wheelchair users. Copyright 2010 by Human Factors and Ergonomics Society, Inc. All rights reserved.
Although human performance on keyboards, pointing devices, and touch screens in the desktop environment has been studied and reported to the extent that the results can be used to determine productivity rates from those devices, little research has been conducted on devices used in controlled environments, like that of point-of-sale in the retail industry. While previous devices available for user interaction in this environment have been 2×20 displays and industry specific keyboards, current technology has moved the industry to implement CRTs, LCDs, full keyboards, touch screens and uniquely designed devices like the NCR DynaKey, an integrated LCD, keypad and dynamically assignable function keys. A full understanding of human performance on these devices was required to aid retailers in cost justifying their investment in them. Laboratory research was conducted to compare performance of basic point-of-sale tasks on a CRT with 56-key keyboard, 3 versions of an LCD touch screen, and the NCR DynaKey. Participants performed keying tasks, item modification tasks, a combination of item modification and scanning, and the same combination of item modification and scanning with a secondary monitoring task imposed. Time and error rates showed significant differences among the user interface devices for each of the task requirements in this research. Overall, mechanically keyed numeric entry was superior to touch screen numeric entry, mechanical keys were more advantageous with increased skill levels, and the integration of input mechanism and display as well as direct mapping between input and display enhanced performance.
Simulated keyboards on touch screens are becoming the norm for data entry on mobile and kiosk systems. Since onscreen keyboards compete with other user interface elements for limited screen space, it is essential that soft keyboard designs are optimally laid out. This paper describes an experiment in which the performance and accuracy of data input on soft keyboards with square key of two different widths (10 and 15mm) and two inter-key gap distances (1.5 and 4.5mm) were evaluated. Three methods of input were studied: finger, stylus, and trackball. Entry times were the shortest and most accurate for stylus touch, although trackball input was the most accurate for the smallest key size. The spacing between keys did not exhibit a significant effect regardless of key size and input method. A key size of 15mm appears to be sufficiently large to provide acceptable accuracy for touch input, although a key size of 10mm was equally acceptable for trackball input.
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The aim of this study was to investigate the effect of button size and spacing on touch characteristics (forces, impulses, and dwell times) during a digit entry touch screen task. A secondary objective was to investigate the effect of disability on touch characteristics. Touch screens are common in public settings and workplaces. Although research has examined the effect of button size and spacing on performance, the effect on touch characteristics is unknown. A total of 52 participants (n = 23, fine motor control disability; n = 14, gross motor control disability; n = 15, no disability) completed a digit entry task. Button sizes varied from 10 mm to 30 mm, and button spacing was 1 mm or 3 mm. Touch characteristics were significantly affected by button size. The exerted peak forces increased 17% between the largest and the smallest buttons, whereas impulses decreased 28%. Compared with the fine motor and nondisabled groups, the gross motor group had greater impulses (98% and 167%, respectively) and dwell times (60% and 129%, respectively). Peak forces were similar for all groups. Button size but not spacing influenced touch characteristics during a digit entry task. The gross motor group had significantly greater dwell times and impulses than did the fine motor and nondisabled groups. Research on touch characteristics, in conjunction with that on user performance, can be used to guide human computer interface design strategies to improve accessibility of touch screen interfaces. Further research is needed to evaluate the effect of the exerted peak forces and impulses on user performance and fatigue.
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Essential tremor (ET) is among the more prevalent neurological disorders, yet prevalence estimates have varied enormously, making it difficult to establish prevalence with precision. We: (1) reviewed the worldwide prevalence of ET in population-based epidemiological studies, (2) derived as precisely as possible an estimate of disease prevalence, and (3) examined trends and important differences across studies. We identified 28 population-based prevalence studies (19 countries). In a meta-analysis, pooled prevalence (all ages) = 0.9%, with statistically significant heterogeneity across studies (I2 = 99%, P < 0.001). In additional descriptive analyses, crude prevalence (all ages) = 0.4%. Prevalence increased markedly with age, and especially with advanced age. In the meta-analysis, prevalence (age ≥ 65 years) = 4.6%, and in additional descriptive analyses, median crude prevalence (age ≥ 60–65) = 6.3%. In one study of those age ≥ 95 years, crude prevalence = 21.7%. Several studies reported ethnic differences in prevalence, although more studies are needed. Greater than one-third of studies show a gender difference, with most demonstrating a higher prevalence among men. This possible gender preference is interesting given clinical, epidemiological, and pathological associations between ET and Parkinson's disease. Precise prevalence estimates such as those we provide are important because they form the numerical basis for planned public health initiatives, provide data on the background occurrence of disease for family studies, and offer clues about the existence of environmental or underlying biological factors of possible mechanistic importance. © 2010 Movement Disorder Society
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The results of a multi-year research program to identify the factors associated with variations in subjective workload within and between different types of tasks are reviewed. Subjective evaluations of 10 workload-related factors were obtained from 16 different experiments. The experimental tasks included simple cognitive and manual control tasks, complex laboratory and supervisory control tasks, and aircraft simulation. Task-, behavior-, and subject-related correlates of subjective workload experiences varied as a function of difficulty manipulations within experiments, different sources of workload between experiments, and individual differences in workload definition. A multi-dimensional rating scale is proposed in which information about the magnitude and sources of six workload-related factors are combined to derive a sensitive and reliable estimate of workload.
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While questionnaires have been developed to capture patient-reported outcomes (PROs) in rheumatology practice, these instruments are not widely used. We developed a touchscreen interface designed to provide reliable and efficient data collection. Using the touchscreen to obtain PROs, we compared 2 different workflow models implemented separately in 2 rheumatology clinics. The Plan-Do-Study-Act methodology was used in 2 cycles of workflow redesign. Cycle 1 relied on off-the-shelf questionnaire builder software, and cycle 2 relied on a custom programmed software solution. During cycle 1, clinic 1 (private practice model, resource replete, simple flow) demonstrated a high completion rate at the start, averaging between 74% and 92% for the first 12 weeks. Clinic 2 (academic model, resource deficient, complex flow) did not achieve a consistent completion rate above 60%. The revised cycle 2 implementation protocol incorporated a 15-minute "nurse visit," an instant messaging system, and a streamlined authentication process, all of which contributed to substantial improvement in touchscreen questionnaire completion rates of ∼80% that were sustained without the need for any additional clinic staff support. Process redesign techniques and touchscreen technology were used to develop a highly successful, efficient, and effective process for the routine collection of PROs in a busy, complex, and resource-depleted academic practice and in typical private practice. The successful implementation required both a touchscreen questionnaire, human behavioral redesign, and other technical solutions.
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This study examined the effect of computer keyboard keyswitch design on muscle activity patterns during finger tapping. In a repeated-measures laboratory experiment, six participants tapped with their index fingers on five isolated keyswitch designs with varying force-displacement characteristics that provided pairwise comparisons for the design factors of (1) activation force (0.31 N vs. 0.59 N; 0.55 N vs. 0.93 N), (2) key travel (2.5mm vs. 3.5mm), and (3) shape of the force-displacement curve as realized through buckling-spring vs. rubber-dome switch designs. A load cell underneath the keyswitch measured vertical fingertip forces, and intramuscular fine wire EMG electrodes measured muscle activity patterns of two intrinsic (first lumbricalis, first dorsal interossei) and three extrinsic (flexor digitorum superficialis, flexor digitorum profundus, and extensor digitorum communis) index finger muscles. The amplitude of muscle activity for the first dorsal interossei increased 25.9% with larger activation forces, but not for the extrinsic muscles. The amplitude of muscle activity for the first lumbricalis and the duration of muscle activities for the first dorsal interossei and both extrinsic flexor muscles decreased up to 40.4% with longer key travel. The amplitude of muscle activity in the first dorsal interossei increased 36.6% and the duration of muscle activity for all muscles, except flexor digitorum profundus, decreased up to 49.1% with the buckling-spring design relative to the rubber-dome design. These findings suggest that simply changing the force-displacement characteristics of a keyswitch changes the dynamic loading of the muscles, especially in the intrinsic muscles, during keyboard work.
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Health status questionnaires are important, especially with the growing interest in outcome studies. However, these questionnaires continue to be administered in their original paper format. We hypothesized that total hip arthroplasty outcome data derived with computer-based questionnaires do not differ significantly from those derived with established paper-based formats. From January 2006 to January 2007, the clinic schedules of four attending arthroplasty surgeons were screened weekly to identify patients who could potentially be included in the study. Charts were reviewed for subjects who were scheduled for or had received primary total hip arthroplasty. Patients were recruited during their office visit or when they attended a preoperative educational class, and five health status questionnaires (the Harris hip score, WOMAC [Western Ontario and McMaster Universities Osteoarthritis Index], SF-36 [Short Form-36], EQ-5D [EuroQol-5D], and UCLA [University of California at Los Angeles] activity score) were administered in three formats: paper, touch screen, and web-based. Repeated-measures analysis of variance and Pearson correlations were used to compare the questionnaire modes for the Harris hip score (normally distributed data), and the Friedman test and Spearman correlations were used to compare the modes for the other health status scores (non-normally distributed data). The study was designed with 90% power for detecting 10% differences between modes in the entire series of sixty-one patients and with 82% and 87% power in preoperative and postoperative subgroups, respectively. The mean age was sixty-three years, with thirty-seven male and twenty-four female patients in the study. Forty-seven hips (77%) had osteoarthritis as the primary diagnosis. No significant differences were detected, for any of the five health outcome systems, among the paper, touch screen, and web-based modes, and there were highly significant correlations among all questionnaire modes in the entire series of patients and in the preoperative and postoperative subgroups (p < 0.001). The scores obtained with the paper, touch screen, and web-based modes of the five questionnaires demonstrated excellent agreement. Thus, touch screen and web-based formats can be used to collect and track patient outcome data. Use of electronic formats of these questionnaires will facilitate a more efficient and reliable data collection process.
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This study aimed to determine the effects of active workstation designs on speed and error during typing, mouse pointing, and combined type and mouse-use tasks. Office ergonomics has focused on musculoskeletal disorder prevention; however, increasing computer-based work also increases health risks associated with inactivity. Workstations allowing computer users to walk or cycle while performing computer tasks have been shown to demand sufficient energy expenditure to result in significant health benefits. However the performance effects of being active while using a computer have not been documented. Thirty office workers (16 female, 15 touch typists) performed standardized computer tasks in six workstation conditions: sitting, standing, walking at 1.6 km/h and 3.2 km/h, and cycling at 5 and 30 watts. Performance, perceived performance, and heart rate were measured. Computer task performance was lower when walking and slightly lower when cycling, compared with chair sitting. Standing performance was not different from sitting performance. Mouse performance was more affected than typing performance. Performance decrements were equal for females and males and for touch typists and nontouch typists. Performance decrements maybe related to both biomechanical and cognitive processes. Active workstations may be less suitable for mouse-intensive work and susceptible users. Although active workstations may result in some decrement in performance, their ability to increase daily energy expenditure may make them a feasible solution for workplace inactivity.
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This paper reports on a study comparing keying accuracy and speed for eight different numeric keypad configurations on a touch screen. Using touch-sensitive keypads displayed on a computer terminal, operators entered numbers presented to them through a speech synthesizer. Dependent measures collected were keying rates, errors, and the x- and y-dimension standard deviations from the centre point of the key. The primary finding was that keypads with square keys resulted in improved speed and a higher degree of accuracy than do keypads with regular keys (either a long horizontal dimension or a longer vertical dimension). Spread-out versions of the keypads (inter-key spacing = 1·3 cm) did not yield superior performance compared with compressed versions (inter-key spacing = 0·6 cm). © 1988 S.Vldaček, L.Kaliterna, B.Radosšvić-Vidaček, S.Folkard.
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This randomized clinical trial evaluated the effects of keyboard keyswitch design on computer users with hand paresthesias. Twenty computer users were matched and randomly assigned to keyboard A (n = 10) or B (n = 10). The keyboards were of conventional layout and differed in keyswitch design. Various outcome measures were assessed during the 12 weeks of use. Subjects assigned keyboard A experienced a decrease in hand pain between weeks 6 and 12 when compared with keyboard B subjects (P = 0.05) and demonstrated an improvement in the Phalen test time (right hand, P = 0.006; left hand, P = 0.06). Keyboard assignment had no significant effect on change in hand function or median nerve latency. We conclude that use of keyboard A for 12 weeks led to a reduction in hand pain and an improved physical examination finding when compared with keyboard B. There was no corresponding improvement in hand function or median nerve latency.
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Despite widespread recommendations regarding posture during computer use, associations between specific postures and musculoskeletal health are not well characterized. Six hundred and thirty-two newly hired computer users were followed prospectively to evaluate associations between posture and neck or shoulder (N/S) and hand or arm (H/A) musculoskeletal symptoms and musculoskeletal disorders. Participants' postures were measured at entry and they reported symptoms on weekly diaries. Participants reporting symptoms were examined for specific disorders. Multivariate Cox regression models were used to estimate associations between postural variables and risk of symptoms and disorders, controlling for confounding variables. Keying with an inner elbow angle > 121 degrees, greater downward head tilt, and presence of armrests on the participants chair were associated with lower risk of N/S symptoms or N/S disorders. Keying with elbow height below the height of the "J" key and the presence of a telephone shoulder rest were associated with a greater risk of N/S symptoms or N/S disorders. Horizontal location of the "J" key > 12 cm from the edge of the desk was associated with a lower risk of H/A symptoms and H/A disorders. Use of a keyboard with the "J" key > 3.5 cm above the table surface, key activation force > 48 g, and radial wrist deviation of > 5 degrees while using a mouse was associated with a greater risk of H/A symptoms or H/A disorders. The number of hours keying/week was associated with H/A symptoms and disorders. The results suggest that the risk of musculoskeletal symptoms and musculoskeletal disorders may be reduced by encouraging specific seated postures.
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To examine the effects of postural and keyswitch characteristics on musculoskeletal tissue loading during tapping on computer keyswitches. We hypothesized that joint torques, stiffness and work parameters differ across keyswitch designs and finger postures typical of those observed during computer keyboard typing. We experimentally measured joint kinematics and calculated joint torques while tapping on different keyswitches in different postures, and analyzed the data using mechanical impedance models. Sixteen human subjects tapped with the index finger on computer keyswitches mounted on a sensor which measured vertical and horizontal forces. Miniature electro-optical goniometers mounted dorsally across each finger joint measured joint kinematics. Joint torques were calculated from endpoint forces and joint kinematics using an inverse dynamics algorithm. A linear spring-damper impedance model was fitted to joint torque, position, and velocity during the contact period of each tap. Subjects tapped in three postures approximating those employed during tapping on three rows of a computer keyboard, on four different keyswitches, resulting in 12 conditions. More extended finger posture was associated with greater joint torques, energies, and stiffnesses, despite minimal differences in endpoint forces across posture. Greater keyswitch make forces were associated with increased forces, joint torques and joint stiffnesses, however this relationship was not monotonic. Joint torques and stiffness parameters differed across keyswitch designs and finger postures. Estimates of joint impedance and work provided a unique perspective into finger dynamics. Determining the causes of work-related musculoskeletal disorders is facilitated by characterizing workplace task biomechanics, which can be linked to specific injury mechanisms.
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In this review, the epidemiological evidence examining associations between upper extremity musculoskeletal symptoms and disorders and keyboard use intensity (hours of computer use-per day or per-week) and computer user posture was explored. An OVID Medline literature search was conducted to identify papers published in the peer-reviewed medical literature between 1966 and November, 2005. A total of 558 citations were found and reviewed. Those papers in which associations between musculoskeletal outcomes and (1) posture (ascertained by a study investigator) or (2) computer use, in units of hours-per-day, hours-per-week, or as a percent of work-time, were included in the review. Thirty-nine epidemiological studies examining associations between computer use and MSD outcomes were identified. While the observational epidemiological literature was heterogeneous, some trends did emerge. It appears that the most consistent finding was the association observed between hours keying and hand/arm outcomes. Associations between some postural effects and musculoskeletal outcomes may also be inferred from the literature. In particular, placing the keyboard below the elbow, limiting head rotation, and resting the arms appears to result in reduced risk of neck/shoulder outcomes. Minimizing ulnar deviation and keyboard thickness appears to result in reduced risk of hand/arm outcomes. Several methodological limitations, including non-representative samples, imprecise or biased measures of exposure and health outcome, incomplete control of confounding, and reversal of cause and effect, may contribute to the heterogeneity of observed results. Suggestions are made for improving the validity of future investigations.