Implementing Ability-Based Design: A Systematic Approach to Conceptual User Modeling
Amelie Nolte, Jacob Wobbrock, Torben Volkmann, Nicole Jochems · 2022 · ACM Transactions on Accessible Computing · doi:10.1145/3551646
Summary
This paper addresses a critical gap in Ability-Based Design (ABD): while the concept has been influential in accessibility research for over a decade, it has lacked a systematic methodology for implementation. ABD, introduced by Wobbrock et al., shifts the design question from "What disability does a person have?" to "What can a person do?"—focusing on abilities rather than deficits and placing the burden of adaptation on systems rather than users. The authors conducted a systematic literature review of 348 papers citing the foundational ABD publications, finding that despite widespread citation, only 55 papers deliberately attempted to realize ABD, and merely 8 addressed conceptual user modeling. This reveals that while ABD's principles are widely endorsed, practitioners lack concrete guidance on how to model users within an ability-based framework. The paper proposes transforming traditional "user models" into "ability models" that capture what users can do in specific task-context combinations. The authors identify three key requirements for modeling abilities: (1) including dynamics—abilities change based on medication, fatigue, environment, and external factors; (2) considering levels of fidelity—abilities can be described broadly or narrowly, each with tradeoffs; and (3) assessing coherence toward tasks and contexts—abilities only have meaning relative to specific activities in specific situations.
Key findings
The authors propose four modifications to traditional requirements analysis to support ABD: 1. **Integrate abilities into task and context**: Rather than analyzing users, tasks, and contexts separately, ability-based requirements analysis must examine abilities in relation to specific task-context pairs. An ability like "seeing" means different things for reading text versus navigating a room. 2. **Articulate technology's ability assumptions**: Every technology embeds assumptions about what users can do. These assumptions must be explicitly surfaced and examined as part of context analysis, enabling designers to identify where systems create barriers. 3. **Consider roles and multiplicity**: Users pursue different tasks in different contexts based on their functional roles. A system for ICU patients must consider both the patient role (communicating needs) and caregiver role (receiving information), each with distinct ability requirements. 4. **Question and adapt set assumptions**: The final step involves critically examining surfaced ability assumptions, identifying enabling and disabling factors, and correcting assumptions that don't match users' actual abilities. The paper demonstrates this framework through two use cases: designing communication systems for ICU patients weaning off ventilators, and creating travel information systems for sign language users. Both reveal how the approach surfaces ability assumptions that traditional methods miss.
Relevance
This work provides the first systematic methodology for implementing Ability-Based Design, making it actionable for practitioners rather than remaining an abstract principle. The framework is directly applicable to any accessibility project where designers need to understand user abilities without relying on disability categories or stereotypes. The distinction between "abilities" and "disabilities" has practical implications: abilities are positive, dynamic, and context-dependent, while disability categories are static and deficit-focused. The proposed ability modeling approach helps designers avoid two common pitfalls—modeling abilities too narrowly (excluding users who don't match precise criteria) or too broadly (forcing designers to rely on their own assumptions). For accessibility practitioners, the key insight is that abilities cannot be modeled in isolation. Any ability-based user model must simultaneously consider the user, the specific task, the context of use, and the technology's embedded assumptions. This integrated approach represents a significant shift from traditional accessibility work that often focuses on disability categories or WCAG criteria in isolation from specific use contexts.
Tags: ability-based design · user modeling · design methodology · requirements analysis · accessible design · inclusive design
Standards referenced: ISO 9241-210:2019