Physical Load While Using a Tablet at Different Tilt Angles during Sitting and Standing

Few standards and guidelines to prevent health problems have been associated with tablet use. We estimated the effects of posture and tablet tilt angle on muscle activity and posture in healthy young adults. Seventeen healthy young adults (age: 20.5 ± 3 years) performed a cognitive task using a tablet in two posture (sitting and standing) and tablet tilt angle (0 degrees and 45 deg) conditions. Segment and joint kinematics were evaluated using 16 inertial measurement unit sensors. Neck, trunk, and upper limb electromyography (EMG) activities were monitored using 12 EMG sensors. Perceived discomfort, kinematics, and EMG activities were compared between conditions using the Friedman test. The perceived discomfort in the standing-0 deg condition was significantly higher than in the remaining three conditions. Standing posture and tablet inclination significantly reduced the sagittal segment and joint angles of the spine, compared with sitting and flat tablet conditions. Similarly, standing posture and tablet inclination significantly reduced EMG activities of the dorsal neck, upper, and lower trunk muscles, while increasing EMG activity of shoulder flexors. Standing posture and tablet inclination reduced the sagittal flexion angle, and dorsal neck, upper, and lower trunk muscle activities, while potentially increasing the muscle activity of arm flexors.

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.

What device should be used for telementoring? Randomized controlled trial

BACKGROUND AND OBJECTIVE

The paper analyzes behavioral patterns of mentors while using different mentoring devices to demonstrate the feasibility of multi-platform mentoring. The fundamental differences of devices supporting telementoring create threats for the perception and interpretation of the transmitted video, highlighting the necessity of exploring hardware usability aspects in a safety critical surgical mentoring scenario.

MATERIALS AND METHODS

Three types of devices, based on the screen size, formed the arms for the randomized controlled trial. Streaming video recordings of a laparoscopic procedure to the mentors imitated the mentoring scenario. User preferences and response times were recorded while participating in a session performed on all devices.

RESULTS

Median response to a mentoring request times were similar for mobile platforms; expected durations were considerably longer for stationary computer. Ability to perceive and identify anatomical structures was insignificantly lower on small sized devices. Stationary and tablet platforms were nearly equally preferred by the most of participants as default telementoring hardware.

DISCUSSION

As a side effect, incompatibility of daily duties of the surgeons in the hospital and telementoring responsibilities while implementing systems locally was identified. Scaling up the use of the service in combination with the organizational changes of clinical staff looks like a promising solution.

CONCLUSION

The trial demonstrated the feasibility of using all three types of devices for the purpose of mentoring, allowing users to choose the preferred platform. The paper provided initial results on the quality assurance of telementoring systems imposed by the regulatory documents.