The role of social support in human-automation interaction.

This theoretical article examines the concept of social support in the context of human-automation interaction, outlining several critical issues. We identified several factors that we expect to influence the consequences of social support and to what extent it is perceived as appropriate (e.g. provider possibilities, recipient expectations), notably regarding potential threats to self-esteem. We emphasise the importance of performance (including extra-role performance) as a potential outcome, whereas previous research has primarily concentrated on health and well-being. We discuss to what extent automation may provide different types of social support (e.g. emotional, instrumental), and how it differs from human support. Finally, we propose a taxonomy of automated support, arguing that source of support is not a binary concept. We conclude that more empirical work is needed to examine the multiple effects of social support for core performance indicators and extra-role performance and emphasise that there are ethical questions involved.

This theoretical article examines the role of automated social support given the increasing ability of automated systems. It concludes that it seems likely that automated systems may be perceived as supportive if they conform to pertinent criteria for design. However, empirical studies are needed to assess the impact of the complex interplay of humans and automation being involved together in the design and provision of social support.

Social stress, performance after-effects and extra-role behaviour.

The article is concerned with the after-effects of social stress on work performance. In a lab-based experiment, seventy participants were assigned to either a stress condition or a no-stress condition. In the stress condition, participants received fake negative performance feedback and they were ostracised by two confederates of the experimenter. Participants carried out the following tasks: attention and divergent creativity. The effects of social stress were examined at three levels: performance after-effects on unscheduled probe tasks, extra-role behaviour and subjective operator state. The manipulation check confirmed that participants experienced social stress. The results showed after-effects of social stress for some forms of extra-role behaviour (i.e. spontaneous reactions) and for the accuracy component of attention. Furthermore, social stress was found to increase negative affect and to reduce self-esteem. The findings point to the importance of assessing different types of after-effects rather than limiting the methodological approach to instant effects on performance.Practitioner summary: The study aimed to examine the multiple effects of social stress. Social stress resulted in increased negative affect and lower self-esteem. Furthermore, social stress was found to reduce the propensity of humans to show extra-role behaviour (i.e. providing spontaneous help to others).

Human and machine-induced social stress and cognitive performance.

The article examines the effects of social stress on work performance in a laboratory study using a battery of performance tests. Social stress was induced by a combination of negative feedback and ostracism. Participants received negative performance feedback and were ostracised by two confederates of the experimenter. Using a one-way experimental design with three levels (machine-induced stress, human-induced stress, and no stress), 102 participants performed the following tasks: attention, divergent and convergent creativity. Participants also completed questionnaires measuring positive and negative affect, and state self-esteem. The manipulation check confirmed that social stress was successfully implemented. The results showed that social stress increased negative affect and reduced self-esteem. However, performance remained unaffected by social stress on any of the cognitive tasks, with no difference emerging between human-induced and machine-induced stress. The findings provide support for the 'blank-out'-mechanism, which assumes that humans can maintain performance levels even under difficult working conditions. Practitioner summary: Social stress in the form of negative performance feedback and social exclusion has a negative impact on the affect and self-esteem of humans. However, performance on subsequent tasks was not impaired. Abbreviations: TSST: trier social stress test; SSES: state self-esteem scale; PANAS: positive and negative affect schedule; ANOVA: analysis of variance.

Effects of social stress on performance and strain in complex multiple task environments.

While stress has been an important research area in the field of ergonomics, research on social stress and on the combination of stressors is largely lacking. This study examined the effects of social stress on psychological and physiological strain and performance. As an exploratory research question we looked at the combined effects of social stress and noise. Fifty-one male student participants were tested for 2 h using a computer-based simulation of a process control environment with multiple tasks. Social stress (TSST) and noise (80 dB) were varied experimentally. During the task, we repeatedly measured primary and secondary task performance, subjective strain, and psychophysiological strain (cortisol, heart rate). We found a main effect of social stress on physiological strain, both on cortisol and heart rate, but no main effects of social stress on subjective strain and performance. These results suggest that maintaining performance under stress comes at the cost of physiological strain. Practitioner summary: Although the presence of social stress is common at work, little experimental work has been done. Our experiment provides empirical evidence for negative effects of social stress on physiological stress responses while subjective strain and performance decrements could not be detected. Abbreviations: ANOVA: analysis of variance; b/min: beats per minute; CAMS: cabin air management system; CO2: carbon dioxide; dB: decibel; Df: degrees of freedom; ECG: electrocardiography; h: hours; Hz: hertz; M: mean; min: minutes; N: sample size; nmol/l: nanomol per liter; O2: oxygen; pm: post meridiem; SD: standard deviation; SE: standard error; sec/s: seconds; TSST: trier social stress test.

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.

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.

Automation in visual inspection tasks: X-ray luggage screening supported by a system of direct, indirect or adaptable cueing with low and high system reliability.

The present study evaluated three automation modes for improving performance in an X-ray luggage screening task. One hundred and forty participants were asked to detect the presence of prohibited items in X-ray images of cabin luggage. Twenty participants conducted this task without automatic support (control group), whereas the others worked with either indirect cues (system indicated the target presence without specifying its location), or direct cues (system pointed out the exact target location) or adaptable automation (participants could freely choose between no cue, direct and indirect cues). Furthermore, automatic support reliability was manipulated (low versus high). The results showed a clear advantage for direct cues regarding detection performance and response time. No benefits were observed for adaptable automation. Finally, high automation reliability led to better performance and higher operator trust. The findings overall confirmed that automatic support systems for luggage screening should be designed such that they provide direct, highly reliable cues.Practitioner summary: The present study confirmed previous findings showing better detection performance in X-ray images of luggage when supported by automation providing direct, highly reliable cues. Furthermore, participants used adaptable automation only to select their preferred level of automation. This behaviour did not provide the benefits expected under adaptable automation.

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.

Operator adaptation to changes in system reliability under adaptable automation.

This experiment examined how operators coped with a change in system reliability between training and testing. Forty participants were trained for 3 h on a complex process control simulation modelling six levels of automation (LOA). In training, participants either experienced a high- (100%) or low-reliability system (50%). The impact of training experience on operator behaviour was examined during a 2.5 h testing session, in which participants either experienced a high- (100%) or low-reliability system (60%). The results showed that most operators did not often switch between LOA. Most chose an LOA that relieved them of most tasks but maintained their decision authority. Training experience did not have a strong impact on the outcome measures (e.g. performance, complacency). Low system reliability led to decreased performance and self-confidence. Furthermore, complacency was observed under high system reliability. Overall, the findings suggest benefits of adaptable automation because it accommodates different operator preferences for LOA. Practitioner Summary: The present research shows that operators can adapt to changes in system reliability between training and testing sessions. Furthermore, it provides evidence that each operator has his/her preferred automation level. Since this preference varies strongly between operators, adaptable automation seems to be suitable to accommodate these large differences.

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.

Experience of automation failures in training: effects on trust, automation bias, complacency and performance.

This work examined the effects of operators' exposure to various types of automation failures in training. Forty-five participants were trained for 3.5 h on a simulated process control environment. During training, participants either experienced a fully reliable, automatic fault repair facility (i.e. faults detected and correctly diagnosed), a misdiagnosis-prone one (i.e. faults detected but not correctly diagnosed) or a miss-prone one (i.e. faults not detected). One week after training, participants were tested for 3 h, experiencing two types of automation failures (misdiagnosis, miss). The results showed that automation bias was very high when operators trained on miss-prone automation encountered a failure of the diagnostic system. Operator errors resulting from automation bias were much higher when automation misdiagnosed a fault than when it missed one. Differences in trust levels that were instilled by the different training experiences disappeared during the testing session. Practitioner Summary: The experience of automation failures during training has some consequences. A greater potential for operator errors may be expected when an automatic system failed to diagnose a fault than when it failed to detect one.

A comparison of adaptive and adaptable automation under different levels of environmental stress.

The effectiveness of different forms of adaptive and adaptable automation was examined under low- and high-stress conditions, in the form of different levels of noise. Thirty-six participants were assigned to one of the three types of variable automation (adaptive event-based, adaptive performance-based and adaptable serving as a control condition). Participants received 3 h of training on a simulation of a highly automated process control task and were subsequently tested during a 4-h session under noise exposure and quiet conditions. The results for performance suggested no clear benefits of one automation control mode over the other two. However, it emerged that participants under adaptable automation adopted a more active system management strategy and reported higher levels of self-confidence than in the two adaptive control modes. Furthermore, the results showed higher levels of perceived workload, fatigue and anxiety for performance-based adaptive automation control than the other two modes. PRACTITIONER SUMMARY: This study compared two forms of adaptive automation (where the automated system flexibly allocates tasks between human and machine) with adaptable automation (where the human allocates the tasks). The adaptable mode showed marginal advantages. This is of relevance, given that this automation mode may also be easier to design.

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.

Some cues are more equal than others: Cue plausibility for false alarms in baggage screening.

This study investigated the effects of cue plausibility in a baggage screening task. 120 participants had to indicate whether a prohibited item was present in a series of grey-scaled X-ray images of baggage. They were assisted by a support system, which pointed at the location of a suspicious object. A 2 × 2 × 2 between-subjects design was used. Cue plausibility for false alarms (i.e. how the cued object was similar to a prohibited item) and support system reliability were manipulated at two levels (high/low). Furthermore, half of participants were provided with a rationale about automation failures (RAF) to reduce their negative impact on trust and performance. The results showed lower performance and more compliance with automation suggestions when cues were implausible than plausible. The RAF increased the response time and did not improve detection performance. Overall, this suggests that effective (computer-based) training is needed to reduce the negative effect of plausible cues.

A Comparison of Conventional and Technology-Mediated Selection Interviews With Regard to Interviewees' Performance, Perceptions, Strain, and Anxiety.

Organizations increasingly use technology-mediated interviews. However, only limited research is available concerning the comparability of different interview media and most of the available studies stem from a time when technology-mediated interviews were less common than in the present time. In an experiment using simulated selection interviews, we compared traditional face-to-face (FTF) interviews with telephone and videoconference interviews to determine whether ratings of interviewees' performance, their perceptions of the interview, or their strain and anxiety are affected by the type of interview. Before participating in the actual interview, participants had a more positive view of FTF interviews compared to technology-mediated interviews. However, fairness perceptions did not differ anymore after the interview. Furthermore, there were no differences between the three interview media concerning psychological and physiological indicators of strain or interview anxiety. Nevertheless, ratings of interviewees' performance were lower in the technology-mediated interviews than in FTF interviews. Thus, differences between different interview media can still be found nowadays even though most applicants are much more familiar with technology-mediated communication than in the past. The results show that organizations should take this into account and therefore avoid using different interview media when they interview different applicants for the same job opening.

The influence of laboratory set-up in usability tests: effects on user performance, subjective ratings and physiological measures.

This article examines the influences of situational factors on user behaviour in usability tests. Sixty participants carried out two tasks on a computer-simulated prototype of a mobile phone. Employing a 3 x 2 mixed experimental design, laboratory set-up was varied as a between-subjects variable (presence of facilitator and two non-interactive observers, presence of facilitator or no person present) while task difficulty was manipulated as a within-subjects variable (low vs. high). Performance data, subjective measures and physiological parameters (e.g. heart rate variability) were taken. The results showed that the presence of non-interactive observers during a usability test led to a physiological stress response, decreased performance on some measures and affected the emotional state of test participants. The presence of a facilitator (i.e. a participating observer) also influenced the emotional state of the test participant. Practitioners involved in usability testing need to be aware of undue influences of observers, in particular, if the observers are non-interactive. The findings presented in this paper have implications for the practice of usability testing. They indicated a considerable influence of observers on test participants (physiology and emotions) and on the outcomes of usability tests (performance measures). This should be considered when selecting the set-up of a usability testing procedure.

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.

Work design for airport security officers: Effects of rest break schedules and adaptable automation.

This study investigated whether there is empirical support for the current EU regulation mandating breaks of at least 10 min after each period of 20 min continuously reviewing X-ray images in airport security screening. As a second goal, it examined whether providing more autonomy to airport security officers (in the form of spontaneous rest breaks and adaptable automation) would improve their performance and subjective state. Seventy-two student participants had to indicate the presence (or absence) of a threat item (either a gun or a knife) in a series of grey-scaled X-ray images of cabin baggage. Three work-rest schedules were examined: spontaneous breaks (i.e. participants could take breaks at any time), two 5-min breaks and two 10-min breaks during a 1-h testing session. Furthermore, half of the participants were assisted in their task by an adaptable support system offering three levels of automation: (1) no support, (2) cues indicating the presence of a potential threat item, and (3) cues indicating the exact location of a potential threat item. Results showed no performance differences between break regimes, which suggests that there may be viable alternatives to the current EU regulations. It also emerged that providing participants with adaptable automation did not lead to better detection performance but resulted in a less positive response bias than participants without automatic support. Implications for current aviation security regulations are discussed.

Expertise, Automation and Trust in X-Ray Screening of Cabin Baggage.

X-ray screening of passenger baggage is a key component in aviation security. The current study investigated how experts and novices performed in an X-ray baggage screening task while being assisted by an adaptable diagnostic aid. Furthermore, it examined how both groups operated and trusted this automated system. 30 experts (certified screeners) and 31 novices (students) had to indicate whether a target item (either a knife or a gun) was present in a series of X-ray images of cabin baggage. Half of the participants could choose between three different support levels of the diagnostic aid (DA): (1) no support, (2) a cue indicating the presence of a potential target without locating it, or (3) a cue indicating the presence of a potential target by surrounding it with a red frame. As expected, experts achieved higher detection performance (d'), were more self-confident and felt more competent in achieving the task than novices. Furthermore, experts experienced less time pressure and fatigue. Although both groups used the DA in a comparable way (in terms of support level used and frequency of level switches), results showed a performance increase for novices working with the DA compared to novices without support. This benefit of DA was not observed for experts. Interestingly, despite no difference in perceived trust ratings, experts were more compliant (i.e., following DA recommendations when it indicated the presence of a target) and reliant (i.e., following DA recommendations when it indicated the absence of a target) than novices. Altogether, the results of the present study suggested that novices benefited more from a DA than experts. Furthermore, compliance and reliance on DA seemed to depend on expertise with the task. Since experts should be better at assessing the reliability of the DA than novices, they may have used the DA as 'back-up' to confirm their decisions based on expertise (confirmatory function), while novices may have used it as a guide to base their decisions on (support function). Finally, trust towards a DA was associated with the degree to which participants found the DA useful.