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Šumak, B.; Kous, K.; Martínez-Normand, L.; Pekša, J.; Pušnik, M. User-Based Testing with Users with Disabilities. Encyclopedia. Available online: (accessed on 02 December 2023).
Šumak B, Kous K, Martínez-Normand L, Pekša J, Pušnik M. User-Based Testing with Users with Disabilities. Encyclopedia. Available at: Accessed December 02, 2023.
Šumak, Boštjan, Katja Kous, Loïc Martínez-Normand, Jānis Pekša, Maja Pušnik. "User-Based Testing with Users with Disabilities" Encyclopedia, (accessed December 02, 2023).
Šumak, B., Kous, K., Martínez-Normand, L., Pekša, J., & Pušnik, M.(2023, July 06). User-Based Testing with Users with Disabilities. In Encyclopedia.
Šumak, Boštjan, et al. "User-Based Testing with Users with Disabilities." Encyclopedia. Web. 06 July, 2023.
User-Based Testing with Users with Disabilities

Human-centered design (HCD) “is an approach to interactive systems development that aims to make systems usable and useful by focusing on the users, their needs and requirements, and by applying human factors/ergonomics, and usability knowledge and techniques“. Developing usable and accessible solutions demands conducting usability testing, also called user-based testing, in which users perform real tasks with a prototype or a real system, usually using one or more specific User Interfaces (UIs). A comprehensive understanding of the challenges users face when using solutions, especially when developing accessible solutions, requires including real users with disabilities in user-based testing. An inclusive HCD approach enables the detection and addressing of real problems and barriers experienced by users with disabilities, ultimately improving usability and accessibility based on their valuable feedback. Involving users with disabilities in user-based testing, on the other hand, requires adequate planning and execution of testing considering the different capabilities and limitations of users with disabilities.

UX evaluation inclusive UX evaluation inclusion of persons with disabilities

1. Introduction

Disability is an umbrella term for impairments, activity limitations, and participation restrictions. It denotes the negative aspects of the interaction between a person’s health condition(s) and that individual’s environmental and personal factors [1]. Persons with disabilities include those who have long-term physical, mental, intellectual, or sensory impairments which, in interaction with various barriers, may hinder their full and effective participation in society on an equal basis with others [2].
According to the World Health Organization’s estimation, 1.3 billion people, representing 16% of the global population, experience a significant disability. The number is growing because of increased noncommunicable diseases and people living longer [3]. Mobility disability, the most common disability, affects 1 in 7 adults [4]. In 2019, it was estimated that 970 million people were living with a mental disorder [5]. Vision impairment affects the quality of life of nearly 2.2 billion people, who often have lower workforce participation and productivity rates and higher rates of depression and anxiety [6][7]. By 2050, nearly 2.5 billion people will have some degree of hearing loss, and at least 700 million will require hearing rehabilitation [8].
Impairments affect many aspects of a person’s life, including communication and speech, cognition, education, employment, etc. For example, persons with brain injury, locked-in syndrome, cerebral palsy, muscular dystrophy, or amyotrophic lateral sclerosis may have limited limb movement ability [9]. People with neuromuscular problems usually lose a degree of autonomy in their daily activities [10]. People with severe disabilities such as amyotrophic lateral sclerosis, motor neuron diseases, cerebral palsy, stroke, and spinal cord injury with intubation have different degrees of communication problems [11]. With ageing, disability becomes more common, affecting around two in five adults aged 65 and older. The number of older people prone to various diseases that impact their effective use of information communication technologies (ICT) is expected to double by 2050 [12].
Disability has become a priority issue in international cooperation for inclusive development [13]. In the 2030 Agenda, disability is recognized as a cross-cutting issue and addressed in the following Sustainable Development Goals [14]: Goal 4—Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all; Goal 8—Promote sustained, inclusive, and sustainable economic growth, full and productive employment, and decent work for all; Goal 10—Reduce inequality within and among countries; Goal 11—Make cities and human settlements inclusive, safe, resilient, and sustainable; and Goal 17—Strengthen the means of implementation and revitalize the Global Partnership for Sustainable Development.
Although there is a tremendous effort in enabling digital inclusion to ensure that every individual has access to information and communication technologies (ICT), people with disabilities are still facing a significant digital divide [15]. Inclusive design is essential to creating products that target a diverse audience. User Interface (UI) designers face different challenges while designing UIs for interactive systems due to the heterogeneity, which can also result from a diversity of end users and interaction modalities [16]. Designers and developers of adaptive applications with UIs able to adapt interaction contents and information processing modes according to users’ needs and disabilities especially face significant difficulties in implementing such applications that meet the dynamic of their environment [17].
Successfully developing usable and accessible solutions demands the design and conducting of usability studies. Usability evaluation can ensure that interactive systems (i.e., software, a website, or any information and communication technology or service) are adapted to the users and their tasks and that their usage has no adverse outcomes [18]. In user-based testing, it is very important to include real end users because only with their feedback can the development process result in applications that best serve the interests of end users. Evaluation by real users is the most valuable technique because it enables the detection of real problems and barriers that users experience while using the solution [19].
In general, when designing and conducting usability testing, it is recommended to follow principles and guidelines provided by existing standards. For applying interaction principles and the general design recommendations for interactive systems, ISO 9241-110:2020 [20] can be followed. A classification of evaluation techniques and guidelines for preparing an evaluation report based on a common industry format and the selected evaluation approach(es) are provided by ISO/IEC 25066:2016 [21]. The standard ISO 9241-210:2019 [22] provides requirements and recommendations for HCD principles and activities throughout the life cycle of computer-based interactive systems.

2. Human-Centered Design (HCD) for Usable and Accessible Solutions

The effective way to achieve high usability in modern solutions is to incorporate human-centered design (HCD) into the development process [23]. HCD “is an approach to interactive systems development that aims to make systems usable and useful by focusing on the users, their needs and requirements, and by applying human factors/ergonomics, and usability knowledge and techniques. This approach enhances effectiveness and efficiency, improves human well-being, user satisfaction, accessibility and sustainability; and counteracts possible adverse effects of use on human health, safety and performance.” [22] In the HCD process, the following principles specified by ISO 9241-210 should be followed [22][24]: (1) understand the user, the task and environmental requirements; (2) encourage the early and active involvement of users; (3) be driven and refined by user-centered evaluation; (4) include iteration of design solutions; (5) address the whole user experience; (6) encourage multi-disciplinary design.
Usability, accessibility, user experience (UX), and HCD have become essential issues to guarantee the quality and success of a software project [25]. When developing solutions tailored to the needs of users with disabilities, the user-centered approach allows understanding the experiences of such users, and based on the results, the usability, UX, and accessibility of these can be improved [26]. Usability is defined by the ISO 9241-11 ergonomics of human–system interaction—Part 11: Usability: Definitions and concepts as [27] “extent to which specified users can use a system, product or service to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use”. UX, on the other hand, is defined as “user’s perceptions and responses that result from the use and/or anticipated use of a system, product or service. Users’ perceptions and responses include the users’ emotions, beliefs, preferences, perceptions, comfort, behaviours, and accomplishments that occur before, during and after use.” [22] Accessibility is defined as “extent to which products, systems, services, environments and facilities can be used by people from a population with the widest range of user needs, characteristics and capabilities to achieve identified goals in identified contexts of use” [27].

3. User-Based Testing with Users with Disabilities

One of the most widely used methods that involves end users is usability testing, also called user-based testing, in which users perform real tasks with a prototype or real system [23], usually using one or more specific UIs. In the iterative user-centered design process, end-user participation is essential for applying techniques such as observation of users, performance-related measurements, questionnaires, interviews, and thinking aloud [28]. Especially when targeting users with disabilities, when it comes to user-based testing, it is essential to involve such users in the process to ensure that the product is usable and accessible to everyone. Usability assessment has been recognized as a critical success factor in developing usable interactive systems with increased productivity, reduced errors, reduced need for user training and user support, and improved acceptance by their users [29].
User-based testing with users with disabilities is paramount for investigating interaction and other difficulties with the product and enhancing the accessibility of a product [30]. Moreover, the expertise of each user, the configuration of the system, and the assistive products [31] utilized by the user are just a few of the variables that can determine whether the user manages to overcome a potential barrier or not [19]. Users can also be asked to explore the product freely while their behaviors are observed and recorded to identify design flaws that cause user errors or difficulties [18]. During the session, a researcher or more researchers observe the participant’s behavior and listen for feedback, enabling different variables to be measured (e.g., task completion time, the accuracy of execution, navigation behavior, etc.). Based on the qualitative and quantitative data analysis, the product’s usability can be improved. The participatory assessment methods with real end users who employ a UI as they work through task scenarios and give feedback provide better insight into the underlying causes of system usability problems users encounter [29].
When user-based testing aims to assess the solution’s performance in terms of the speed of performing tasks or errors when using the solution, it does not matter which users that are included. Existing research has shown that performance of users with disabilities while testing a product can be very close to the performance of users without disabilities [26][32][33]. However, when analyzing and comparing the benefits of products for users with disabilities, the results between users with disabilities and users without disabilities can differ significantly. The difference could be attributed to the greater utilization of new technology’s advantages to people with disabilities, while those without disabilities take less advantage of the benefits or do not even need them as much. For example, the study by Giudice et al. demonstrated that older adults who are blind or have a visual disability and experience difficulties in navigating could significantly benefit from a navigation system, and evaluating older participants with a visual disability is important, as the majority of vision loss is related to age [32].


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