The influence of product aesthetics and user state in usability testing

An empirical study examined the effects of two influencing factors in usability tests on user performance and usability ratings. Product aesthetics (high vs. low) as the main independent factor and prior usage event (positive vs. negative) as a subsidiary independent factor were varied in a between-participants design. 60 participants took part in the experiment, completing a number of typical tasks of mobile phone users. The results showed that increased product aesthetics had a positive effect on perceived usability and led to longer task completion times. After a negative usage event had been experimentally induced, usability ratings dropped as expected but user performance on subsequent tasks remained unaffected. An important implication of the study is that the aesthetic properties of a product may have multiple effects that go beyond perceived product attractiveness.     

The influence of prototype fidelity and aesthetics of design in usability tests: effects on user behaviour, subjective evaluation and emotion

An empirical study examined the impact of prototype fidelity on user behaviour, subjective user evaluation and emotion. The independent factors of prototype fidelity (paper prototype, computer prototype, fully operational appliance) and aesthetics of design (high vs. moderate) were varied in a between-subjects design. The 60 participants of the experiment were asked to complete two typical tasks of mobile phone usage: sending a text message and suppressing a phone number. Both performance data and a number of subjective measures were recorded. The results suggested that task completion time may be overestimated when a computer prototype is being used. Furthermore, users appeared to compensate for deficiencies in aesthetic design by overrating the aesthetic qualities of reduced fidelity prototypes. Finally, user emotions were more positively affected by the operation of the more attractive mobile phone than by the less appealing one.     

The influence of user expertise and prototype fidelity in usability tests

An empirical study examined the impact of user expertise and prototype fidelity on the outcomes of a usability test. User expertise (expert vs. novice) and prototype fidelity (paper prototype, 3D mock-up, and fully operational appliance) were manipulated as independent variables in a 2 × 3 between-subjects design. Employing a floor scrubber as a model product, 48 users carried out several cleaning tasks. Usability problems identified by participants were recorded. Furthermore, performance, system management strategies and perceived usability were measured. The results showed that experts reported more usability problems than novices but these were considered to be less severe than those reported by novices. Reduced fidelity prototypes were generally suitable to predict product usability of the real appliance. The implications for the running of usability tests are specific to the fidelity of the prototype.     

The influence of design aesthetics in usability testing: Effects on user performance and perceived usability

This article examined the effects of product aesthetics on several outcome variables in usability tests. Employing a computer simulation of a mobile phone, 60 adolescents (14-17 yrs) were asked to complete a number of typical tasks of mobile phone users. Two functionally identical mobile phones were manipulated with regard to their visual appearance (highly appealing vs not appealing) to determine the influence of appearance on perceived usability, performance measures and perceived attractiveness. The results showed that participants using the highly appealing phone rated their appliance as being more usable than participants operating the unappealing model. Furthermore, the visual appearance of the phone had a positive effect on performance, leading to reduced task completion times for the attractive model. The study discusses the implications for the use of adolescents in ergonomic research.     

Webpage aesthetics,performance and usability: Design variables and their effects

The primary objectives of this research are to identify the underlying clusters of design variables affecting the perceived usability of a webpage and to examine the effects of webpage design variables on webpage performance. Fifty-seven design variables and 10 underlying clusters that conceptualise the structure of user webpage judgement are identified through content analysis on literature and structured interviews, balanced incomplete block user survey administration and cluster analysis. Five clusters are selected to conduct three experiments that quantify the change in user aesthetic preference, perceived ease of interaction and interaction speed as a function of loading speed, image colour, image size, font size, link style, and column width. Results show that user performance alone is not a good indicator of aesthetic judgement and overall effectiveness of a webpage. The value of integrating global construct analysis processes and local controlled experimentation processes in ergonomic interface research is illustrated. Fifty-seven webpage design variables are defined, ranked and clustered according to perceived importance and overall preference. Experimental results illustrate that both technical performance and aesthetic factors are important webpage design considerations.     

The effects of usability and web design attributes on user preference for e-commerce web sites

This study examines the relationships among perceived usability before actual use, task completion time, and preference, and the effects of design attributes on user preference for e-commerce web sites. Nine online bookstore web sites were used by ten participants. Results indicate: (1) pre-use usability and task completion time were correlated; (2) the relationship between pre-use usability and preference was greater than that of task completion time and preference; (3) design attribute assessments after actual use were highly intercorrelated; and (4) organizational structure and layout had a greater effect on user preference than aesthetic aspects, such as color and typography. These findings can be used to construct a conceptual framework for understanding user preferences and to develop design guidelines to yield more highly preferred e-commerce web sites. Also, the methodology in this study can be applied to other computerized-applications.     

The influence of the search complexity and the familiarity with the website on the subjective appraisal of aesthetics,mental effort and usability

The user experience is defined as ‘a person's perceptions and responses that result from the use and/or anticipated use of a product, system or service’ (ISO FDIS 9241-210, 2009 ISO FDIS 9241-210, 2009. Ergonomics of human system interaction Ergonomics of human system interaction – Part 210: human-centered design for interactive systems (formerly known as 13407). Switzerland: International Organization for Standardization. [Google Scholar]) [Ergonomics of human system interaction Ergonomics of human system interaction – Part 210: human-centered design for interactive systems (formerly known as 13407). Switzerland: International Organization for Standardization]. Accordingly, some authors have argued that an interactive system has to be evaluated not only with regard to its usability and utility levels, but also with regard to emotional, attractiveness, and aesthetic levels. These last aspects play a substantial role on the general assessment of such systems and on the satisfaction of users. Some studies focused on the immediate aesthetic subjective perception of systems, on their subjective usability and preference perceptions. However, few studies, at least to our knowledge, have been focused on the reverse, that is, on the effect of difficulties experienced by individuals in using systems on the aesthetic appraisal. The present study aimed at determining the role of familiarity level with the website and the search complexity on the search performance and post-experiment appraisals of aesthetics, usability, and mental effort. The main results revealed that the search complexity affected negatively search performance, whereas the familiarity level affected only the re-reading of the search questions. The post-use assessments of aesthetics, mental effort, and usability satisfaction were affected by search performance. In addition, these variables were correlated except the expressive aesthetics, which seemed to be independent from the search performance and other subjective appraisals. Then, we discuss these findings in line with prior studies and present future ways of research.     

Effects of touchscreen gesture’s type and direction on finger-touch input performance and subjective ratings

Abstract

This study examined how finger-touch input performance (i.e. task completion time, failure status, and error rate) and subjective ratings (i.e. performance and physical demand) are influenced by touchscreen gestures’ type and direction. Twenty participants performed one-touch (i.e. drag and swipe) and two-touch (i.e. pinch and spread) gesture tasks on a tablet, using several major directions (i.e. eight directions for one-touch and four directions for two-touch gestures). The results showed that swipe was approximately 4.5 times faster than drag, but pinch and spread showed no significant difference in task completion time. Dragging and pinching showed more failures or higher error rates compared to swiping and spreading, respectively. One-touch gestures in the horizontal directions were rated to have higher performance and lower physical demand than those in the vertical and diagonal directions. Two-touch gestures in the horizontal directions took the shortest time but caused more failures and higher error rates.

Practitioner Summary: This study provides evidence for the effects of touchscreen gestures’ type and direction on human performance and subjective ratings, which varied depending on the number of fingers used. Designers should arrange related touchscreen components accordingly, to improve touch-finger input performance and reduce user workload.     

Product design and apparent usability. The influence of novelty in product appearance

This research enhances our understanding of the relationship between aesthetics and usability by investigating the effects of novelty in product appearance on the apparent usability of a product. In two experimental studies using washing machines and digital cameras as stimuli, we systematically manipulated the level of novelty (low vs. high) in the product appearance by changing the product's color or shape. Participants were presented with one of these product appearances and a list of the product's technical specifications. Next, participants indicated how difficult or easy they expected the usage of the product to be. Our findings demonstrate that because people associate a high level of novelty with technological advancement, novelty in a product appearance negatively affects their expectations of a product's usability at the point of sale. Furthermore, novices are more likely to use the level of novelty as a cue for a product's apparent usability than experts.     

The effects of knee angles on subjective discomfort ratings, heart rates, and muscle fatigue of lower extremities in static-sustaining tasks

The purpose of this study was to investigate the effects of knee-flexion angles on subjective discomfort ratings, heart rates, and muscle fatigue using median frequency (MDF) in a static-sustaining task. Thirty healthy participants maintained 13 postures including standing, squatting, sitting, and kneeling postures and then MDFs from the erector spinae, biceps femoris, vastus medialis, gastrocnemius, and tibialis anterior muscles, subjective discomfort, and heart rates were collected every 3 min during a sustained 15 min task. Results showed that the discomfort, heart rate and muscle fatigue were significantly influenced by the body postures. In general, standing and sitting postures showed less discomfort as well as lower heart rates, whereas squatting postures (KF120, KF90, KF60) had higher discomfort and heart rates. Three MDF change trends were reported associated with postures in this study. First, there were less changes of MDFs for standing and sitting postures; second, all patterns of MDFs for KF 150 and KF120 decreased, and lastly some MDFs had increasing trends and others showed decreasing trends for KF30, KF30T, and kneeling postures.     

The influence of product aesthetics and usability over the course of time: a longitudinal field experiment

A longitudinal field experiment was carried out over a period of 2 weeks to examine the influence of product aesthetics and inherent product usability. A 2 × 2 × 3 mixed design was used in the study, with product aesthetics (high/low) and usability (high/low) being manipulated as between-subjects variables and exposure time as a repeated-measures variable (three levels). A sample of 60 mobile phone users was tested during a multiple-session usability test. A range of outcome variables was measured, including performance, perceived usability, perceived aesthetics and emotion. A major finding was that the positive effect of an aesthetically appealing product on perceived usability, reported in many previous studies, began to wane with increasing exposure time. The data provided similar evidence for emotion, which also showed changes as a function of exposure time. The study has methodological implications for the future design of usability tests, notably suggesting the need for longitudinal approaches in usability research. PRACTITIONER SUMMARY: This study indicates that product aesthetics influences perceived usability considerably in one-off usability tests but this influence wanes over time. When completing a usability test it is therefore advisable to adopt a longitudinal multiple-session approach to reduce the possibly undesirable influence of aesthetics on usability ratings.     

Assessment and monitoring of mental workload in subway train operations using physiological,subjective, and performance measures

Subway train operation is a complex, sociotechnical system that involves a variety of cognitively demanding tasks. The train operators are responsible for continuously monitoring the surrounding environment, maintaining awareness, processing information, and making decisions under risk. The resulting mental strain on operators can negatively affect their performance and the interaction of the human–machine system. The objective of this study was to evaluate if physiological, subjective, and performance measures could identify the level of mental workloads arising from routine and nonroutine operations in the subway system. A total of 11 subway train operators underwent different driving scenarios in a high‐fidelity simulator. The simulated tasks were divided into two categories: routine operations (preparing to drive and driving between stations without interruptions or emergencies) and nonroutine operation (responding to a tunnel fire, dealing with a high density of passengers, encountering a passenger/technician on the track, and responding to train failure). The mental workload was monitored and evaluated in these tasks using an electrocardiogram, subjective self‐rating scales, and driving performance. Both heart rate variability and performance measures (including reaction time and error rate) detected mental workload variations in the different operations. On the other hand, the subjective ratings (including NASA‐TLX) assessed the overall mental workload associated with a task, without explaining the mental demand variations within the task over time. Subway train drivers experienced different levels of mental workload during routine and nonroutine driving conditions. The findings of this study can be used to extract mental workload limits to optimize workload levels during train operations.     

Online recruiting: The effects of organizational familiarity, website usability, and website attractiveness on viewers’ impressions of organizations

Previous research on Internet recruitment has made the implicit assumption that recruitment websites influence viewers’ opinions of recruiting organizations. This study tested this assumption using a pretest/posttest design. Findings revealed that participants’ organizational favorability, image as employer, and organizational attractiveness perceptions were affected by their viewing of organizational recruitment websites. Greater increases in favorable organizational evaluations from the pretest measures to the posttest measures occurred with organizations maintaining websites that were easy to navigate and/or that were appealing. Contrary to predictions made by signaling theory, recruitment websites had similar effects on the organizational impressions of all individuals, regardless of their familiarity with the organizations maintaining the recruitment websites that they viewed.     

Neuroergonomic analysis of perihand space: effects of hand proximity on eye-tracking measures and performance in a visual search task

According to recent studies, cognitive processes are modulated by the proximity of the hands to a stimulus. Specifically, hand proximity (also known as nearby-hand or hand-presence effects) induces a bias to process information near the hands more precisely and this effect can be facilitative or debilitative depending on the task context. Two different distances of the hands in reference to the screen were studied as independent variables: hands placed on the screen and hands placed on the lap. The dependent variables were search times and different eye-tracking parameters. Given the age-related decline in the perception of peripersonal space, the results were analysed for two different age groups. Overall, we found a more detailed evaluation of information near the hands depending on age. In conclusion, the study presents a cognitive behavioural evaluation of human–computer interaction which can be used for touchscreen interface and interaction design as well as modelling human–system interaction.     

年龄对利用脉搏波估计心率和心率变异性的准确性的影响

由于测量简便,脉搏波被广泛用于替代心电计算心率和心率变异性,但其准确性颇受争议。该文探讨了年龄对利用脉搏波估计心率和心率变异性准确性的影响,实验招募了 100 名年龄广泛分布在 20～71 岁的健康者,同步采集静息脉搏波和心电图,利用脉搏波相邻峰值点的时间间隔序列,计算受试者的瞬时心率和心率变异性,并将其与利用心电相邻两个 R 波峰值点计算的心率/心率变异性(金标准)进行对比,计算利用脉搏波估计心率和心率变异性的误差。实验结果表明,心率估计误差在 40 岁以下的年轻人中较小(标准差在 0.3 搏/min 左右),在 40 岁以上的中老年人中较大(标准差在 0.7 搏/min 左右),时域的心率变异性参数的规律类似。因此,即使在静息条件下,利用脉搏波峰值点计算老年人的心率/心率变异性也要谨慎对待。     

The effect of testing location on usability testing performance, participant stress levels, and subjective testing experience

The effect of testing location on usability test elements such as stress levels and user experience is not clear. A comparison between traditional lab testing and synchronous remote testing was conducted. The present study investigated two groups of users in remote and traditional settings. Within each group participants completed two tasks, a simple task and a complex task. The dependent measures were task time taken, number of critical incidents reported, and user-reported anxiety score. Task times differed significantly between the physical location condition; this difference was not meaningful for real world application, and likely introduced by overhead regarding synchronous remote testing methods. Critical incident reporting counts did not differ in any condition. No significant differences were found in user reported stress levels. Subjective assessments of the study and interface also did not differ significantly. Study findings suggest a similar user testing experience exists for remote and traditional laboratory usability testing.     

Exploring the wiki user experience: The effects of training spaces on novice user usability and anxiety towards wiki editing

With the advent of Web 2.0, the number of IT systems used in university courses is growing. Yet research consistently shows that a significant proportion of students are anxious about computer use. The quality of first experience with computers has been consistently mentioned as a significant contributor to anxiety onset. However the effect of users’ first experience on system related anxiety has not to the authors’ knowledge been researched using controlled experiments. Indeed little experiment based research has been conducted on the wiki user experience, specifically users’ evaluations and emotional reactions towards editing. This research uses usability engineering principles to engineer four different wiki experiences for novice wiki users and measures the effect each has on usability, anxiety during editing and on anxiety about future wiki editing. Each experience varied in the type of training spaces available before completing six live wiki editing tasks. We found that anxiety experienced by users was not related to computer anxiety but was wiki specific. Users in the in-built tutorial conditions also rated the usability of the editing interface higher than users in the non-tutorial conditions. The tutorial conditions also led to a significant reduction in wiki anxiety during interaction but did not significantly affect future editing anxiety. The findings suggest that the use of an in-built tutorial reduces emotional and technological barriers to wiki editing and that controlled experiments can help in discovering how aspects of the system experience can be designed to affect usability and anxiety towards editing wikis.     

Driving in an urban environment,the stress response and effects of exercise

Driving may be detrimental to health, with one hypothesis suggesting that driving may elicit an acute stress response and, with repeated exposures, may become a chronic stressor. The present study examined the stress response to driving and the effectiveness of a prior exercise bout in dampening this response. Twenty healthy adults performed three tasks: control, driving and exercise plus driving. Heart rate (HR), heart rate variability (HRV), blood pressure (BP) and cortisol were measured to quantify the acute stress response to each condition. Data indicated a stress response to driving: HR was elevated and HRV was reduced during the driving task compared with control. HR was elevated and HRV was reduced comparing the exercise plus driving with the driving condition. BP and cortisol were not different among conditions. The potential of interventions, such as exercise, to counter daily stressors should be evaluated to safeguard long-term health.

Practitioner Summary: this study confirms that driving induces a stress response, with the exercise intervention providing mixed results (an increase in cardiovascular measures and a decrease in cortisol measure trending significance). Given the known consequences of stress and evidence that exercise can mitigate acute stress, further evaluation of exercise interventions is recommended.     

The effects of air temperature on office workers’ well-being, workload and productivity-evaluated with subjective ratings

Productivity bears a close relationship to the indoor environmental quality (IEQ), but how to evaluate office worker’s productivity remains to be a challenge for ergonomists. In this study, the effect of indoor air temperature (17 °C, 21 °C, and 28 °C) on productivity was investigated with 21 volunteered participants in the laboratory experiment. Participants performed computerized neurobehavioral tests during exposure in the lab; their physiological parameters including heart rate variation (HRV) and electroencephalograph (EEG) were also measured. Several subjective rating scales were used to tap participant’s emotion, well-being, motivation and the workload imposed by tasks. It was found that the warm discomfort negatively affected participants’ well-being and increased the ratio of low frequency (LF) to high frequency (HF) of HRV. In the moderately uncomfortable environment, the workload imposed by tasks increased and participants had to exert more effort to maintain their performance and they also had lower motivation to do work. The results indicate that thermal discomfort caused by high or low air temperature had negative influence on office workers’ productivity and the subjective rating scales were useful supplements of neurobehavioral performance measures when evaluating the effects of IEQ on productivity.     

Evaluation of upper-limb body postures based on the effects of back and shoulder flexion angles on subjective discomfort ratings,heart rates and muscle activities

A possible limitation of many ergonomics checklists that evaluate postures is an independent evaluation of each body segment without considering the coordination between body segments and resulting in the under-/over-estimation of body postures. A total of 20 men were selected to evaluate the effects of shoulder and back flexion angles on the upper-limb muscle activities, subjective discomforts and heart rates. Interesting findings were obtained from the coordination between back flexion angles and shoulder flexion angles. At a back flexion angle of 45°, the discomfort and heart rates were the least at a shoulder flexion angle of 45°. The %MVC also showed a similar trend. It could be inferred that the 0° shoulder flexion angle would be a natural posture, when the back flexion angle is 0°, whereas 45° shoulder flexion might be a more natural posture when the back flexion angle is 45°.

Statement of Relevance: This study evaluated the effects of back and shoulder flexion angles on subjective as well as objective measures. The findings of this study considered the coordination between two body flexion angles and could be used to improve the accuracy of existing ergonomics evaluation methods for body postures.