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Toward Usability Evaluation for Brain–Computer Interfaces
Published in Chang S. Nam, Anton Nijholt, Fabien Lotte, Brain–Computer Interfaces Handbook, 2018
Ilsun Rhiu, Yushin Lee, Inchul Choi, Myung Hwan Yun, Chang S. Nam
NASA-TLX is a popular mental workload assessment technique that relies on a multidimensional construct. It derives overall workload based on six subscales: mental demand, physical demand, temporal demand, performance, effort, and frustration (Cao et al. 2009). VAS is one method for assessing a “feeling” (Ohnhaus and Adler 1975). It is usually conducted to assess the satisfaction of a system in BCI usability studies. The ATD-PA device form and QUEST 2.0 are specialized subjective assessment tools to evaluate assistive devices. ATD-PA is a set of questionnaires to assess the matching between person and assistive technology (Scherer and Craddock 2002). In BCI usability studies, only a set of 12 items, called ATD-PA device form, is usually utilized to ask users’ views of 12 aspects of using a proposed BCI system as an assistive device. QUEST 2.0 is an instrument to evaluate users’ satisfaction with assistive technology. It contains 12 items rated on a five-point satisfaction scale with respect to a device and services (Demers et al. 2002). The SUS survey and the USE Questionnaire are simple, yet effective tools for assessing the usability of various products. The SUS survey contains a 10-item scale giving a global view of usability (Bangor et al. 2009), and the USE Questionnaire contains a 14-item scale referring to four domains: satisfaction, ease of use, ease of learning, and usefulness (Lund 2001). IBM computer usability satisfaction questionnaires also measure user satisfaction with usability, but it is specialized to a computer system (Lewis 1995). QCM is a subjective assessment tool specialized to measuring users’ motivations with respect to four motivational factors: mastery confidence, incompetence fear, challenge, and interest (Rheinberg et al. 2001).
Human–Robot Interaction for Rehabilitation Robots
Published in Pedro Encarnação, Albert M. Cook, Robotic Assistive Technologies, 2017
Wing-Yue Geoffrey Louie, Sharaf Mohamed, Goldie Nejat
The NASA-TLX tool (Hart and Staveland 1988) is designed to assess physical and cognitive workload. The NASA-TLX consists of users performing a pairwise comparison of workload factors, as well as giving a rating to each factor individually. The results from the pairwise comparison in conjunction with the individual ratings are used to produce an overall score for the workload. Workload is defined as a hypothetical construct that represents the cost incurred by a human operator to achieve a particular level of performance. The questionnaire divides workload into six factors: (1) mental demand; (2) physical demand; (3) temporal demand; (4) performance; (5) effort; and (6) frustration level. Mental demand is defined as the amount of mental and perceptual activity required (e.g., easy/demanding, simple/complex, and exacting/forgiving). Physical demand is the amount of physical activity required (e.g., easy/demanding, slow/brisk, slack/strenuous, and restful/laborious). How much time pressure was felt due to the pace of the task is defined as temporal demand (e.g., slow and leisurely/rapid and frantic). Performance is how successful the user believed he or she was in accomplishing the task goals (e.g., self-satisfaction). Effort is how hard the user had to work to accomplish the level of performance, and frustration level is how frustrated the user felt during the task (e.g., insecure/secure, irritated/relaxed, and stressed/content). The NASA-TLX tool is most commonly used for rehabilitation applications involving exoskeletons, as these tasks tend to be extremely stressful and demanding on users (Schiele 2009; Zimmerli et al. 2012); furthermore, the questionnaire has also been used with other, nonwearable, robotic systems (Chen and Kemp 2010; Shirzad and Van der Loos 2015).
The influence of team workload on team performance in the light of task complexity: a study of nuclear fire brigades
Published in International Journal of Occupational Safety and Ergonomics, 2023
Veronika Klara Takacs, Marta Juhasz
The NASA TLX has been developed following a multi-year research effort to identify and isolate factors that play an important role in experiencing workload. It is a multidimensional subjective workload-rating technique, according to which workload is ‘the cost incurred by human operators to achieve a particular level of performance’ [19,p.144]. It uses six dimensions to assess mental workload: mental demand (how much mental and perceptual activity was required during the task); physical demand (how much physical activity was required during the task); temporal demand (how much time pressure one felt due to the rate or pace at which the task or task elements occurred); performance (how successful one thinks he/she was in accomplishing the goals of the task set by the experimenter); effort (how hard one had to work – mentally and physically – to accomplish his/her level of performance); and frustration (how insecure, discouraged, irritated, stressed and annoyed one felt during the task). Participants are asked to assign a score from 0 to 100 to each of the dimensions according to the extent to which they think the dimension has contributed to their workload (tally). This is followed by a paired comparison task of the dimensions (weight). As the last step, tallies are multiplied by the weights in the case of each dimension (adjusted rating), are summed up and are finally divided by 15. This will be the weighted rating of the given task (see Figure 1.).
Investigating the relationship between job stress, workload and oxidative stress in nurses
Published in International Journal of Occupational Safety and Ergonomics, 2022
Jamal Biganeh, Azadeh Ashtarinezhad, Davood Behzadipour, Narges Khanjani, Atefeh Tavakoli Nik, Majid Bagheri Hosseinabadi
Among the workload estimation tools, the NASA task load index (NASA-TLX) is one of the most widely used tools in the field, developed by Hart and Staveland in 1988. This tool has two parts. In the first part the crude score is calculated (Raw-TLX), and in the second part the adaptive weighted workload (AWWL) is calculated. The first part of this tool consists of six subscales, which include mental demand, physical demand, temporary demand, performance, effort and frustration. Each of these subscales were scored from 0 to 100, based on their importance. In the second part, the aforementioned scales were compared in pairs (15 pairs in total) and, depending on their importance and effectiveness, one of them was selected by the participants. The weighted factors were used in the final estimation of the workload [34]. The validity and reliability of this questionnaire in Farsi was confirmed by Haghi et al. [35] and Ghorbani [36].
The relationship between individual, physical and psychosocial risk factors with musculoskeletal disorders and related disabilities in flight security personnel
Published in International Journal of Occupational Safety and Ergonomics, 2022
Mohsen Sadeghi Yarandi, Mohammad Ghasemi, Ali Ghanjal
This questionnaire was used to assess mental workload. The NASA task load index (NASA-TLX) is a multidimensional approach that provides an overall score of workload based on a weighted average for six scales of intellectual and mental demand, physical demand, temporal demand, effort, overall performance and frustration level. The participant scores each of the six dimensions from 0 to 100 based on their working conditions. Using the hierarchical analytical method, the importance of each dimension relative to the other dimensions is examined. In this case, the person chooses the option that is most relevant to the activity between the two cases. Each selection is equal to a weighted score for that item. By multiplying the weight of each dimension of the workload (ranging from 0 to 1) by the scale score for each dimension (ranging from 0 to 100), the total workload of the individual is calculated numerically from 0 to 100. In fact, the overall score is expressed as a weighted workload. According to the questionnaire, if the overall workload score is less than 50 the risk level is low and if it is above 50 the risk level is high. The validity and reliability of this questionnaire have been confirmed in previous studies (Cronbach's α = 0.897) [33,34]. The questions and definitions for each of the subscales of this questionnaire are presented in Table 1.