Usability, user experience and accessibility: towards an integrative model.

Within the field of ergonomics, the concepts of usability, user experience and accessibility have played an increasingly important role. The present paper examined the meaning of these concepts and their relationship to each other, which included an analysis of the definitions, methods, and typical outcome measures employed. Despite some concerns in the literature about the utility of usability, user experience and accessibility as umbrella terms, we provide arguments for their continued use. The article proposes how the three concepts and their different perspectives can be integrated. We propose the term 'interaction experience' (IX) as a higher-level concept. Due to the multi-facetted nature of umbrella concepts, we suggest using spider charts as a means to report the results of evaluating artefacts with regard to usability, user experience and accessibility. Practitioner Summary: A better integration of the concepts of usability, user experience and accessibility is expected to provide some benefits to practitioners. We propose employing spider charts for reporting the outcome of artefact evaluations regarding the three concepts. This may help practitioners interpret the characteristics of a device at a glance. Abbreviations: IX: interaction experience; UX: user experience; ISO: International Standard Organisation.

Social stress and performance in human-machine interaction: a neglected research field.

Given the increasing capabilities of highly automated systems, the article argues for a need to address the issue of social stress in human-machine interaction. It suggests a classification system of subordinate concepts found in the research literature under the heading of social stress. A review of the literature revealed a paucity of studies examining the effects of social stressors on performance. In particular, the review showed a shortage of experimental lab-based work, needed to establish clear cause-effect relationships. The article examined the suitability of different social stressors for lab-based research, not only when humans are the source of stress but also in so-called hybrid teams where social stress is caused by machine agents. The review shows that a closer link is needed between the separate literature on social stress and automation. Finally, three mechanisms are proposed that may predict how social stress may affect performance: 'blank-out'-mechanism, 'rumination'-mechanism, and 'increased-motivation'-mechanism. Practitioner summary: Theories of ergonomics and human factors may benefit from better integration of research and theoretical work in the domain of social stress. This is due to the increasing capabilities of machines to induce social stress. Abbreviations: HMI: human-machine interaction; TSST: trier social stress test.

Easy-to-read language in disability-friendly web sites: Effects on nondisabled users.

This article examines the influence of using easy-to-read language (as an important web accessibility criterion to support users with disabilities) on nondisabled users. A web site usability test was conducted with 128 nondisabled participants. Each participant evaluated one of two web site versions: conventional language vs. easy-to-read language. Measures of performance (e.g., recognition of content and reading time) and subjective user reactions (e.g., perceived usability and text liking) were taken. The results showed that easy-to-read language (compared to conventional language) led to improvements for some performance measures (e.g., recognition of content) but also to increased reading time, decreased text liking and reduced intention to revisit the web site. This article concludes that when implementing easy-to-read language in web sites, adverse as well as beneficial effects on nondisabled users need to be considered.

Effects of accessible website design on nondisabled users: age and device as moderating factors.

This study examined how implementing recommendations from Web accessibility guidelines affects nondisabled people in different age groups using different technical devices. While recent research showed positive effects of implementing such recommendations for nondisabled users, it remains unclear whether such effects would apply to different age groups and kind of devices. A 2 × 2 × 2 design was employed with website accessibility (high accessibility vs. very low accessibility), age (younger adults vs. older adults) and type of device (laptop vs. tablet) as independent variables. 110 nondisabled participants took part in a usability test, in which performance and satisfaction were measured as dependent variables. The results showed that higher accessibility increased task completion rate, task completion time and satisfaction ratings of nondisabled users. While user age did not have any effects, users showed faster task completion time under high accessibility when using a tablet rather than a laptop. The findings confirmed previous findings, which showed benefits of accessible websites for nondisabled users. These beneficial effects may now be generalised to a wide age range and across different devices. Practitioner Summary: This work is relevant to the design of websites since it emphasises the need to consider the characteristics of different user groups. Accessible website design (aimed at users with disabilities) leads to benefits for nondisabled users across different ages. These findings provide further encouragement for practitioners to apply WCAG 2.0.

Implementing Recommendations From Web Accessibility Guidelines: A Comparative Study of Nondisabled Users and Users With Visual Impairments.

OBJECTIVE: The present study examined whether implementing recommendations of Web accessibility guidelines would have different effects on nondisabled users than on users with visual impairments. BACKGROUND: The predominant approach for making Web sites accessible for users with disabilities is to apply accessibility guidelines. However, it has been hardly examined whether this approach has side effects for nondisabled users. A comparison of the effects on both user groups would contribute to a better understanding of possible advantages and drawbacks of applying accessibility guidelines. METHOD: Participants from two matched samples, comprising 55 participants with visual impairments and 55 without impairments, took part in a synchronous remote testing of a Web site. Each participant was randomly assigned to one of three Web sites, which differed in the level of accessibility (very low, low, and high) according to recommendations of the well-established Web Content Accessibility Guidelines 2.0 (WCAG 2.0). Performance (i.e., task completion rate and task completion time) and a range of subjective variables (i.e., perceived usability, positive affect, negative affect, perceived aesthetics, perceived workload, and user experience) were measured. RESULTS: Higher conformance to Web accessibility guidelines resulted in increased performance and more positive user ratings (e.g., perceived usability or aesthetics) for both user groups. There was no interaction between user group and accessibility level. CONCLUSION: Higher conformance to WCAG 2.0 may result in benefits for nondisabled users and users with visual impairments alike. APPLICATION: Practitioners may use the present findings as a basis for deciding on whether and how to implement accessibility best.

Implementing Recommendations From Web Accessibility Guidelines: Would They Also Provide Benefits to Nondisabled Users.

OBJECTIVE: We examined the consequences of implementing Web accessibility guidelines for nondisabled users. BACKGROUND: Although there are Web accessibility guidelines for people with disabilities available, they are rarely used in practice, partly due to the fact that practitioners believe that such guidelines provide no benefits, or even have negative consequences, for nondisabled people, who represent the main user group of Web sites. Despite these concerns, there is a lack of empirical research on the effects of current Web accessibility guidelines on nondisabled users. METHOD: Sixty-one nondisabled participants used one of three Web sites differing in levels of accessibility (high, low, and very low). Accessibility levels were determined by following established Web accessibility guidelines (WCAG 2.0). A broad methodological approach was used, including performance measures (e.g., task completion time) and user ratings (e.g., perceived usability). RESULTS: A high level of Web accessibility led to better performance (i.e., task completion time and task completion rate) than low or very low accessibility. Likewise, high Web accessibility improved user ratings (i.e., perceived usability, aesthetics, workload, and trustworthiness) compared to low or very low Web accessibility. There was no difference between the very low and low Web accessibility conditions for any of the outcome measures. CONCLUSION: Contrary to some concerns in the literature and among practitioners, high conformance with Web accessibility guidelines may provide benefits to users without disabilities. APPLICATION: The findings may encourage more practitioners to implement WCAG 2.0 for the benefit of users with disabilities and nondisabled users.

The influence of age in usability testing.

The effects of age in usability testing were examined in an experiment. Sixty users from two age groups (M = 23.0 yrs, M = 58.1 yrs) operated two technical devices (keyboard-based and touchscreen-based smartphones). In addition to various performance measures (e.g. task completion time, task completion rate), several subjective measures were taken (e.g. perceived usability, affect, and workload). The results showed better performance scores for younger adults than older adults for task completion time. For older adult users there was a mismatch between usability ratings and task completion time but not between usability ratings and task completion rate. Age-related differences in the importance of speed and accuracy in task completion point to the need to consider more strongly the factor user age in usability research and practice.