Posture and discomfort assessment in computer users while using touch screen device as compared with mouse-keyboard and touch pad-keyboard

BACKGROUND

Touch screen computers require significant arm and hand movements. This can result to body discomfort and biomechanical load in users.

OBJECTIVES

This study was carried out to examine posture and users' discomfort while using touch screen device as compared with mouse-keyboard and touch pad-keyboard.

METHODS

Twenty three (23) students participated in this experimental study. The subjects completed pre-defined tasks in three 15 min trials by means of touch screen, touch pad-keyboard and mouse-keyboard as input devices. Postural angles were measured by Qualisys motion capture system. Body discomfort was assessed by a 10-cm visual analog scale. Rating scale was employed to assess the perception of subjects on the posture of body parts while utilizing the three devices.

RESULTS

There was no significant difference in head inclination when using the three types of devices. Nevertheless, the mean of neck (p = 0.005) and trunk (p < 0.0001) inclinations as well as arm angle (p < 0.0001) while using touch screen, differed significantly from the two other devices and were more deviated from neutral posture. The type of input device was found to have significant effect on the right shoulder (p = 0.017), right elbow (p = 0.031), right wrist/hand (p = 0.004) and whole body discomfort (p = 0.026). Touch screen caused more discomfort in the mentioned regions when compared to the other two devices. Friedman test showed that differences of mean ratings for perceived shoulder and elbow postures in the 3 trials were significant (p = 0.005 and p = 0.011, respectively). Touch screen was the most unfavorable input device based on the subjects' judgment.

CONCLUSION

Touch screen caused more deviated postural angles, increased body discomfort and unfavorable postures.

Examining the Usability of Touch Screen Gestures for Older and Younger Adults

OBJECTIVE

We examined the usability issues associated with four touch screen gestures (clicking, dragging, zooming, and rotating) among older and younger users.

BACKGROUND

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.

METHOD

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.

RESULTS

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.

CONCLUSION

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.

APPLICATION

The implications are useful for the design of large touch screen applications, such as desktop computers, information kiosks, and health care support systems.

Examining User Preferences in Interacting with Touchscreen Devices

The introduction of touchscreen technology has remarkably changed how people interact with their devices. Users may adopt different methods of input depending on the type of device they are interacting with and the type of task being performed. In the present study, we collected data on users’ preferences with regards to interface interaction, device position, and posture, while performing various tasks with four different touch screen devices: a touchscreen desktop, laptop, iPad or iPod Touch. Results indicated that users prefer touch over traditional input devices when performing more interactive tasks (ex: drawing, gaming). We also observed that the device position adopted by users may promote suboptimal flexion angles of the torso, neck and wrists. The information gleaned from this study contributes to the limited body of knowledge on the ergonomic implications of touch screen devices.