Mobile technology dominates school children’s IT use in an advantaged school community and is associated with musculoskeletal and visual symptoms

This paper describes the contemporary use of information technology devices by children in a socio-educationally advantaged school. A sample of 924 children (50% girls) from grades 5 to 12 (ages 10–19 years) completed an online survey in class. Total daily technology use was high and similar for girls (mean 219 (SD 148) mins/day) and boys (207 (142), p=.186). Tablet computer was the dominant device used in grades 5–9, with laptop computer the dominant device in grades 10–12. Patterns of exposure were influenced by gender, device, grade and purpose of use interactions. For example, girls used mobile phones more than boys for social purposes for grades 10 and 11, but not grade 12. Whilst children’s attitudes to technology use were positive, musculoskeletal and visual symptoms were commonly reported. Hours/day tablet and phone use was related to neck/shoulder discomfort (OR = 1.07; 1.13) and visual symptoms (OR = 1.10; 1.07).

Practitioner Summary: Technology use by children appears to be quite different now to a decade ago. This paper describes contemporary school children’s use of various devices for various purposes. The survey of >900 children found high technology use, dominated by new mobile technologies, and associations with musculoskeletal and visual symptoms.     

Notifications Efficiency,Impact, and Interference in Second-Screen Scenarios

The growing use of second-screen devices stresses the importance of finding a balance between engagement, distraction, and disturbance of its users, while simultaneously watching television. In this framework, this article reports on a study designed to analyze the efficiency, impact, and interference of different notification strategies aiming to identify the best approach to be used when an alert is needed in second-screen scenarios.

A prototype able to deliver synchronized information related with TV content, with intervals of 10, 30 and 60 s, followed by individual or combined notifications (e.g., audio, visual, and haptic—on the tablet and visual—on the TV) was developed. A laboratory adapted to replicate a living room was set up and a test that involved watching three segments of a 20-min clip while using the prototype was carried with 30 participants, under a cognitive walk-through protocol.

Quantitative and qualitative results show that receiving notifications while watching TV is effective in alerting users about new information, despite its inherent cognitive disturbance for the TV viewing experience. It was also possible to highlight that in an HCI perspective, the most suitable strategy for integrating notifications (considering type and cadence) should be based on a combination of a visual notification (displayed only on the TV screen) along with a haptic notification (vibration on the tablet); spaced by an interval of at least 30 s.     

A Picture is Worth a Thousand Words: Source Credibility Theory Applied to Logo and Website Design for Heightened Credibility and Consumer Trust

Websites are often the first or only interaction a consumer has with a firm in modern commerce. Because consumers tend to make decisions within the first few seconds of online interaction, the first impression given to users can greatly determine a website's success. Leveraging source credibility theory, a strategy is presented for building credibility derived from a user's initial impressions of a website, in online environments. The study demonstrates that logos designed to communicate traits of credibility (i.e., expertise and trustworthiness) can trigger positive credibility judgments about the firm's website and that this increase in perceived credibility results in greater trust and willingness to transact with the firm. In addition, the study demonstrates distinct effects on consumers’ distrusting beliefs. The positive trust effects are magnified when the design of a website extends and complements the credibility-based logo design. This practice-supporting model further indicates how website designers can methodically design logos and websites that nonverbally communicate credibility information within the first few moments of a website interaction.

[Supplemental materials are available for this article. Go to the publisher's online edition of the International Journal of Human–Computer Interaction to view the free supplemental file: Online Appendix A.]     

Effects of foot placement,hand positioning,age and climbing biodynamics on ladder slip outcomes

Ladder falls frequently cause severe injuries; yet the factors that influence ladder slips/falls are not well understood. This study aimed to quantify (1) the effects of restricted foot placement, hand positioning, climbing direction and age on slip outcomes, and (2) differences in climbing styles leading to slips versus styles leading to non-slips. Thirty-two occupational ladder users from three age groups (18–24, 25–44 and 45–64 years) were unexpectedly slipped climbing a vertical ladder, while being assigned to different foot placement conditions (unrestricted vs. restricted toe clearance) and different hand positions (rails vs. rungs). Constraining foot placement increased the climber's likelihood of slipping (p < 0.01), while younger and older participants slipped more than the middle-aged group (p < 0.01). Longer double stance time, dissimilar and more variable foot and body positioning were found in styles leading to a slip. Maintaining sufficient toe clearance and targeting ladder safety training to younger and older workers may reduce ladder falls.

Practitioner Summary: Ladder falls frequently cause severe occupational fall injuries. This study aims to identify safer ladder climbing techniques and individuals at risk of falling. The results suggest that ladders with unrestricted toe clearance and ladder climbing training programmes, particularly for younger and older workers, may reduce ladder slipping risk.     

A randomised control trial of the cognitive effects of working in a seated as opposed to a standing position in office workers

Sedentary behaviour is increasing and has been identified as a potential significant health risk, particularly for desk-based employees. The development of sit-stand workstations in the workplace is one approach to reduce sedentary behaviour. However, there is uncertainty about the effects of sit-stand workstations on cognitive functioning. A sample of 36 university staff participated in a within-subjects randomised control trial examining the effect of sitting vs. standing for one hour per day for five consecutive days on attention, information processing speed, short-term memory, working memory and task efficiency. The results of the study showed no statistically significant difference in cognitive performance or work efficiency between the sitting and standing conditions, with all effect sizes being small to very small (all ds < .2). This result suggests that the use of sit-stand workstations is not associated with a reduction in cognitive performance.

Practitioner Summary: Although it has been reported that the use of sit-stand desks may help offset adverse health effects of prolonged sitting, there is scant evidence about changes in productivity. This randomised control study showed that there was no difference between sitting and standing for one hour on cognitive function or task efficiency in university staff.     

Grasp and index finger reach zone during one-handed smartphone rear interaction: effects of task type,phone width and hand length

Recently, some smartphones have introduced index finger interaction functions on the rear surface. The current study investigated the effects of task type, phone width, and hand length on grasp, index finger reach zone, discomfort, and muscle activation during such interaction. We considered five interaction tasks (neutral, comfortable, maximum, vertical, and horizontal strokes), two device widths (60 and 90 mm) and three hand lengths. Horizontal (vertical) strokes deviated from the horizontal axis in the range from ?10.8° to ?13.5° (81.6–88.4°). Maximum strokes appeared to be excessive as these caused 43.8% greater discomfort than did neutral strokes. The 90-mm width also appeared to be excessive as it resulted in 12.3% increased discomfort relative to the 60-mm width. The small-hand group reported 11.9–18.2% higher discomfort ratings, and the percent maximum voluntary exertion of their flexor digitorum superficialis muscle, pertaining to index finger flexion, was also 6.4% higher. These findings should be considered to make smartphone rear interaction more comfortable.

Practitioner Summary: Among neutral, comfortable, maximum, horizontal, and vertical index finger strokes on smartphone rear surfaces, maximum vs. neutral strokes caused 43.8% greater discomfort. Horizontal (vertical) strokes deviated from the horizontal (vertical) axis. Discomfort increased by 12.3% with 90-mm- vs. 60-mm-wide devices. Rear interaction regions of five commercialised smartphones should be lowered 20 to 30 mm for more comfortable rear interaction.     

Evaluation of Three Tablet Computers at Two Levels of Ambient Illumination

Background: Tablet computers are increasingly widespread in this digital era. During tablet computer use, two important factors are display quality and ambient illumination. The purpose of this experiment was to understand the effects of the display quality of tablet computers (a Sony, a Samsung, and an iPad) and ambient illumination levels (200 lx, 500 lx) on visual fatigue, comfort perception, and task performance.

Methods: Thirty-five university students (17 males and 18 females) were recruited for this experiment. They performed six 40-min trials of playing computer games in all experimental conditions. Visual fatigue, comfort perception, and task performance were collected at the end of each trial.

Results and Discussion: There were no interactions between display model and ambient illumination. Display model had a significant effect on visual fatigue and visual performance, and the best display quality caused less visual fatigue during long periods of viewing. We found no significant effect between 200 lx and 500 lx of ambient illumination on visual fatigue or visual performance; therefore, further research should be conducted to determine what levels of ambient illumination, both high and low, can affect visual fatigue and task performance.     

The Proactive and Preventive Privacy (3P) Framework for IoT Privacy by Design

The Problem

Internet of Things (IoT) is providing new services and insights by sensing contextual data but there are growing concerns of privacy risks from users that need immediate attention.

The Reason

The IoT devices and smart services can capture Personally Identifiable Information (PII) without user knowledge or consent. The IoT technology has not reached the desired level of maturity to standardize security and privacy requirements.

The Solution

IoT Privacy by Design is a user-centric approach for enabling privacy with security and safety as a ‘win-win’ positive outcome of IoT offerings, irrespective of business domain. The Proactive and Preventive Privacy (3P) Framework proposed in this paper should be adopted by the IoT stakeholders for building trust and confidence in end users about IoT devices and smart services.     

Too hot to carry on? Disinclination to persist at a task in a warm office environment

We investigated the effect of an elevated ambient temperature on performance in a persistence task. The task involved the coding of incorrect symbols and participants were free to decide how long to spend performing this task. Applying a between-subject design, we tested 125 students in an office-like environment in one of the three temperature conditions. The comfort condition (Predicted Mean Vote [PMV] = 0.01) featured an average air temperature of 24 °C. The elevated ambient temperature condition was 28 °C (PMV = 1.17). Condition three employed an airstream of approximately 0.8 m/s, intended to compensate for performance decrements at the elevated air temperature (28 °C, PMV = 0.13), according to Fanger’s thermal comfort equation. Participants in the warm condition were significantly less persistent compared with participants in the control and compensation conditions. As predicted by the thermal comfort equation, the airstream seemed to compensate for the higher temperature. Participants’ persistence in the compensation and comfort conditions did not differ.

Practitioner Summary: A laboratory experiment involving a simulated office environment and three ambient temperature conditions (24 °C, 28 °C and 28 °C plus airstream) showed that persistence at a task is significantly impaired at 28 °C. An airstream of 0.8 m/s at 28 °C compensated for the disinclination to persist with the task.     

Lift performance and lumbar loading in standing and seated lifts

This study investigated the effect of posture on lifting performance. Twenty-three male soldiers lifted a loaded box onto a platform in standing and seated postures to determine their maximum lift capacity and maximum acceptable lift. Lift performance, trunk kinematics, lumbar loads, anthropometric and strength data were recorded. There was a significant main effect for lift effort but not for posture or the interaction. Effect sizes showed that lumbar compression forces did not differ between postures at lift initiation (Standing 5566.2?±?627.8 N; Seated 5584.0?±?16.0) but were higher in the standing posture (4045.7?±?408.3 N) when compared with the seated posture (3655.8?±?225.7 N) at lift completion. Anterior shear forces were higher in the standing posture at both lift initiation (Standing 519.4?±?104.4 N; Seated 224.2?±?9.4 N) and completion (Standing 183.3?±?62.5 N; Seated 71.0?±?24.2 N) and may have been a result of increased trunk flexion and a larger horizontal distance of the mass from the L5-S1 joint.

Practitioner Summary: Differences between lift performance and lumbar forces in standing and seated lifts are unclear. Using a with-in subjects repeated measures design, we found no difference in lifted mass or lumbar compression force at lift initiation between standing and seated lifts.     

Gender difference in mobile phone use and the impact of digital device exposure on neck posture

This cross-sectional study aimed to identify gender differences in the cervical postures when young adults were using mobile phones, as well as the correlations between the postures and the digital devices use (computer and mobile phone). Questionnaires regarding the habits of computer and mobile phone use were administrated to 429 subjects aged from 17 to 33 years old (19.75 ± 2.58 years old). Subjects were instructed to stand habitually and use a mobile phone as in daily life; the sagittal head and cervical postures were measured by head flexion, neck flexion angle and gaze angle. Male participants had a significantly larger head flexion angle (96.41° ± 12.23° vs. 93.57° ± 12.62°, p = 0.018) and neck flexion angle (51.92° ± 9.55° vs. 47.09° ± 9.45°, p < 0.001) than females. There were significant differences in head (F = 3.62, p = 0.014) and neck flexion (F = 3.99, p = 0.009) between different amounts of computer use.

Practitioner Summary: We investigated possible gender differences in head and neck postures of young adults using mobile phones, as well as the potential correlations between these postures and digital device use. We found that males displayed larger head and neck flexion angles than females, which were associated with the amount of computer use.     

Medium-term effects of a two-desk sit/stand workstation on cognitive performance and workload for healthy people performing sedentary work: a secondary analysis of a randomised controlled trial

Implementing sit/stand workstations in sedentary work environments is a common way to reduce sedentary time, but their medium-term effect on cognitive performance is unclear. To address this circumstance, eighteen office workers participated in a two-arm, randomised controlled cross-over trial (ClinicalTrials.gov Identifier: NCT02825303), either working at a traditional (sit) or an interventional (sit/stand) workplace for 23 weeks. Cognitive performance (working speed, reaction time, concentration performance, accuracy), workload and relevant covariates (salivary cortisol level, heart rate, physical activity, sitting time) were measured pre- and post-intervention under laboratory conditions. MANOVA and RMANOVA results did not show differences in performance parameters and workload, respectively, between sit/stand and traditional workplace users. Differences in text editing accuracy and cortisol levels for sit/stand workstation users indicate potential connectivity to cognitive parameters which should be further examined with large-scale studies. Practitioner summary: Medium-term effects of working at sit/stand workstations on cognitive performance and workload are unexplored. This randomised controlled trial suggests that cognitive performance and workload are unaffected for sit/stand workstation users after 23?weeks of use. However, accuracy appeared to improve and physiological stress appeared to be altered.

Abbreviations: BMI: body mass index; IPAQ: International physical activity questionnaire; MET: metabolic equivalent of task; MANOVA: multivariate ANOVA; NASA TLX: NASA task load index; RMANOVA: repeated measures ANOVA     

A modified version of the three-compartment model to predict fatigue during submaximal tasks with complex force-time histories

The three-compartment model (3CM) was validated previously for prediction of endurance times by modifying its fatigue and recovery rates. However, endurance times do not typically represent work demands, and it is unknown if the current version of the 3CM is applicable for ergonomics analysis of all occupational tasks. The purpose of this study was to add biological fidelity to the 3CM, and validate the model against a series of submaximal force plateaus. The fatigue and recovery rates were modified to represent graded physiological motor unit characteristics (termed 3CM_GMU). In nine experiments of submaximal efforts, the 3CM_GMU produced a root-mean squared difference (RMSD) of 4.1 ± 0.5% MVC over experiments with an average strength loss (i.e. fatigue) of 31.0 ± 1.1% MVC. The 3CM_GMU model performed poorly for endurance tasks. The 3CM_GMU model is an improvement for evaluating submaximal force patterns consisting of intermittent muscle contractions of the hand and forearm.

Practitioner Summary: We modified an existing fatigue model using known physiological properties in order to predict fatigue during nine different submaximal force profiles; consistent with efforts seen in industrial work. We expect this model to be included in digital human modelling software, for the assessment of repetitive work and muscle fatigue in repetitive tasks.

Social Media Summary: The proposed model has applications for estimating task fatigue in proactive ergonomic analyses of complex force patterns using digital human models.     

Measuring working memory load effects on electrophysiological markers of attention orienting during a simulated drive

Intersection accidents result in a significant proportion of road fatalities, and attention allocation likely plays a role. Attention allocation may depend on (limited) working memory (WM) capacity. Driving is often combined with tasks increasing WM load, consequently impairing attention orienting. This study (n = 22) investigated WM load effects on event-related potentials (ERPs) related to attention orienting. A simulated driving environment allowed continuous lane-keeping measurement. Participants were asked to orient attention covertly towards the side indicated by an arrow, and to respond only to moving cars appearing on the attended side by pressing a button. WM load was manipulated using a concurrent memory task. ERPs showed typical attentional modulation (cue: contralateral negativity, LDAP; car: N1, P1, SN and P3) under low and high load conditions. With increased WM load, lane-keeping performance improved, while dual task performance degraded (memory task: increased error rate; orienting task: increased false alarms, smaller P3).

Practitioner Summary: Intersection driver-support systems aim to improve traffic safety and flow. However, in-vehicle systems induce WM load, increasing the tendency to yield. Traffic flow reduces if drivers stop at inappropriate times, reducing the effectiveness of systems. Consequently, driver-support systems could include WM load measurement during driving in the development phase.     

Muscle activity patterns and spinal shrinkage in office workers using a sit–stand workstation versus a sit workstation

Reducing sitting time by means of sit–stand workstations is an emerging trend, but further evidence is needed regarding their health benefits. This cross-sectional study compared work time muscle activity patterns and spinal shrinkage between office workers (aged 24–62, 58.3% female) who used either a sit–stand workstation (Sit–Stand group, n = 10) or a traditional sit workstation (Sit group, n = 14) for at least the past three months. During one typical workday, muscle inactivity and activity from quadriceps and hamstrings were monitored using electromyography shorts, and spinal shrinkage was measured using stadiometry before and after the workday. Compared with the Sit group, the Sit–Stand group had less muscle inactivity time (66.2 ± 17.1% vs. 80.9 ± 6.4%, p = 0.014) and more light muscle activity time (26.1 ± 12.3% vs. 14.9 ± 6.3%, p = 0.019) with no significant difference in spinal shrinkage (5.62 ± 2.75 mm vs. 6.11 ± 2.44 mm). This study provides evidence that working with sit–stand workstations can promote more light muscle activity time and less inactivity without negative effects on spinal shrinkage.

Practitioner Summary: This cross-sectional study compared the effects of using a sit–stand workstation to a sit workstation on muscle activity patterns and spinal shrinkage in office workers. It provides evidence that working with a sit–stand workstation can promote more light muscle activity time and less inactivity without negative effects on spinal shrinkage.     

The ageing Australian firefighter: an argument for age-based recruitment and fitness standards for urban fire services

Currently, there is no enforcement of physical standards within Australian fire services post-recruitment, possibly leading to inappropriate fitness and body composition. This study evaluated the impacts of ageing on physical standards of Australian firefighters. Seventy-three firefighters from three different 10-year age groups [25–34 years (n = 27), 35–44 years (n = 27), 45–54 years (n = 19)] volunteered for physical testing using dual-energy X-ray analysis and existing fitness tests used for recruitment by an Australian fire service. Older (45–54 years) participants demonstrated significantly poorer physical standards compared with younger participants including cardiovascular fitness (p < 0.05), strength (p = 0.001) and simulated operational power testing tasks (p < 0.001). Age-related body composition changes were also observed independent of body mass index. Minimum recruitment standards and fitness programs need to account for age-related declines in physical capabilities to ensure that the minimum standard is maintained regardless of age.

Practitioner Summary: Using dual-energy X-ray analysis and established fitness testing protocols, this study aimed to gain an appreciation of the current standards of body composition and fitness of Australian firefighters and the effects of ageing on their physical abilities post-recruitment. The study demonstrated a significant decline in physical standards due to age.     

Normative data on the one-handed static pull strength of a Chinese population and a comparison with American data

We assess the one-handed static pull strength of a Chinese population and compare it to that of an American sample. Fifty men and 50 women in five age groups were asked to exert their maximum one-handed pull strength in three pulling directions (across, front and side) and from four pulling heights (61 cm, 76 cm, waist height and above-shoulder height). The results showed that women had less pull strength than men under all of the conditions tested. The front and side pulling resulted in the greatest pull strength, with a decrease detected when the pulling height was increased. The American sample exhibited greater strength than the Chinese. Body mass and men’s handgrip force were also associated with the pull strength. These variables should be taken into account in the development of tasks related to one-handed pulling.

Practitioner summary:

In this paper, we report a laboratory-based experiment conducted to assess the one-handed static pull strength of a Chinese population and compare the results with those of an American population. The variables associated with pull strength included gender, pulling direction, pulling height, race, body mass and men’s handgrip force.     

A comfort assessment of existing cervical orthoses

Purpose: Identify location and intensity of discomfort experienced by healthy participants wearing cervical orthoses.

Method: Convenience sample of 34 healthy participants wore Stro II, Philadelphia, Headmaster, and AspenVista^® cervical orthoses for four-hour periods. Participants reported discomfort level (scale 0–6) and location.

Results: Participants reported mean discomfort for all orthoses over the four-hour test between ‘a little discomfort’ and ‘very uncomfortable’ (mean discomfort score = 1.64, SD = 1.50). Seven participants prematurely stopped tests due to pain and six reported maximum discomfort scores. Significant linear increase in discomfort with duration of wear was found for all orthoses. Significantly less discomfort was reported with Stro II than Headmaster and Philadelphia. Age correlated with greater perceived discomfort. Orthoses differed in the location discomfort was experienced.

Conclusion: Existing cervical orthoses cause discomfort influenced by design and duration of wear with orthoses’ design the more significant factor. This work informed the design of a new orthosis and future orthoses developments.

Practitioner Summary: The purpose of this study was to gain greater knowledge about the discomfort caused by wearing of existing neck orthoses in order to inform the design and development of a new neck orthosis. This study gathers empirical data from a surrogate population and concludes that orthosis design is more influential than the duration of wear.     

Jerry can carriage is an effective predictor of stretcher carry performance

Carrying a casualty on a stretcher is a critical task conducted in a range of occupations. To ensure that personnel have the requisite physical capacity to conduct this task, two bilateral jerry can carries were used to predict individual performance in a four-person stretcher carry. Results demonstrated a bilateral 22-kg jerry can carry (R² = 0.59) had superior predictive ability of stretcher carry performance than a bilateral 15-kg jerry can carry (R² = 0.46). Pre- to post-carry changes in grip endurance (p > 0.05), back–leg isometric strength (p > 0.05) and leg power (p > 0.05) were not significantly different between carry tasks. There was no significant difference in heart rate (p > 0.05) and oxygen consumption (p > 0.05) between the stretcher carry and either jerry can carry. Thus, on the basis of performance correlations and physiological measures, the 22-kg jerry can carry is an appropriate predictive assessment of four-person stretcher carriage.

Practitioner Summary: This study investigated the ability of a jerry can carry to predict individual performance on a four-person stretcher carry. Performance correlations were substantiated with physiological measures to demonstrate similar physical requirements between task and test. These results can be used to set physical employment standards to assess stretcher carriage.