Human–Computer Interaction and Accessible Design

Introduction and Context

Human–Computer Interaction (HCI) is the interdisciplinary study of how people interact with computing systems and how those systems can be designed to support human goals, capabilities, and well-being. It draws on computer science, psychology, cognitive science, design, ergonomics, sociology, communication, and accessibility studies.

HCI is not limited to graphical user interfaces. It includes websites, mobile applications, operating systems, command-line tools, information appliances, wearable devices, intelligent assistants, virtual and augmented reality, cyber-physical systems, and social computing platforms. Its central concern is the relationship among users, technologies, tasks, and contexts.

Accessible design is a fundamental part of HCI. It seeks to ensure that people with diverse sensory, physical, cognitive, linguistic, and technological circumstances can perceive, understand, navigate, and operate digital systems. Accessibility is not a special feature added after development; it is a quality dimension of responsible system design.

At postgraduate level, HCI should be understood both as a design discipline and as an analytical field. A technically functional system may still fail because it is difficult to learn, inefficient, inaccessible, unsafe, culturally inappropriate, or inconsistent with users’ real practices. HCI therefore asks not only whether a system works, but also for whom it works, under what conditions, at what cost, and with what consequences.

Learning Objectives

After studying this chapter, students should be able to:

1. Define HCI, usability, user experience, and accessibility, and distinguish their scopes.
2. Explain major HCI theories and interaction models.
3. Analyse users, tasks, contexts, and stakeholder requirements.
4. Apply user-centred and human-centred design methods.
5. Evaluate interfaces using usability metrics and empirical methods.
6. Design for users with disabilities using principles such as perceivability, operability, understandability, and robustness.
7. Critically assess ethical, organisational, cultural, and regulatory dimensions of interface design.
8. Integrate accessibility and inclusive practice throughout the software development life cycle.

1. Core Concepts and Terminology

1.1 User, stakeholder, and context

A user directly interacts with a system. A stakeholder may be affected by it without directly operating it; examples include supervisors, parents, regulators, support staff, and members of the public. A context of use includes the physical, social, organisational, technical, and temporal conditions in which interaction occurs.

The same interface may be usable in a quiet office but unusable in sunlight, on a slow network, while walking, or during an emergency. Consequently, requirements should describe realistic contexts rather than an abstract “average user.”

1.2 Usability

Usability concerns the extent to which specified users can achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context. Effectiveness concerns task accuracy and completeness; efficiency concerns resources such as time and effort; satisfaction concerns perceived comfort and acceptability.

A useful task-completion rate is:

The measure assumes that task success has been defined consistently and that attempts are comparable. It should not be interpreted alone: a high completion rate may conceal excessive time, errors, or assistance.

Mean task time is:

Here, tᵢ is the time taken by participant i, and n is the number of valid observations. Times should use the same unit, such as seconds, and unusual failures should be reported rather than silently removed.

1.3 User experience

User experience (UX) includes usability but extends to emotion, trust, aesthetics, meaning, identity, anticipation, and experience before, during, and after use. A banking application may be usable yet produce poor UX if it creates anxiety about security or communicates errors disrespectfully.

1.4 Accessibility and inclusion

Accessibility is the degree to which products, services, environments, and information can be used by people with the widest possible range of abilities. Inclusive design is a broader approach that seeks to accommodate human diversity from the outset. Universal design aims to make products usable by as many people as possible without adaptation, although specialised adaptations remain important.

Accessibility and usability overlap but are not identical. A visually attractive interface may be inaccessible to a screen-reader user; an accessible interface may still have confusing workflows. Both dimensions must be evaluated.

1.5 Affordances, signifiers, and feedback

An affordance is a possible action enabled by an object or interface. A signifier communicates where and how that action may be performed. A button affords activation, while its label, shape, and placement signify that it is actionable. Feedback communicates the result of an action. Without feedback, users may repeat actions, assume failure, or lose trust.

Constraints limit possible actions and can prevent errors. Mapping describes the relationship between controls and their effects. Consistency allows knowledge learned in one part of a system to transfer to another.

2. Theoretical Foundations and Interaction Models

2.1 The human as an information-processing system

Traditional cognitive models describe interaction as perception, interpretation, decision, action, and evaluation. This model helps designers consider attention, memory, mental models, and workload. However, it should not be treated as a complete description of human behaviour. Social context, emotion, culture, embodiment, and organisational practices also shape interaction.

Working memory is limited, so interfaces should reduce unnecessary recall. Recognition is generally easier than recall; menus, autocomplete, examples, and visible status can therefore reduce cognitive burden. Excessive notifications, animation, choices, and interruptions increase workload and can impair decision quality.

2.2 Mental models

A mental model is a user’s understanding of how a system works. Designers possess a conceptual model—the explanation embodied in the design—while users construct operational models from experience, language, and feedback. Usability improves when the conceptual model is communicated clearly and aligns with users’ expectations.

For example, a document editor that uses a familiar “trash” metaphor can make deletion understandable. Metaphors must nevertheless be tested: cultural differences and modern technologies may make a metaphor unfamiliar to some users.

2.3 Norman’s action cycle

A widely used model describes interaction through seven stages: forming a goal, forming an intention, specifying an action, executing it, perceiving the system state, interpreting that state, and evaluating the outcome. The execution gap occurs when users cannot determine how to perform an intended action. The evaluation gap occurs when they cannot understand what the system did.

Designers reduce these gaps through visible controls, meaningful labels, immediate feedback, clear system status, reversible actions, and error messages that explain recovery.

2.4 The Model Human Processor and performance

Human-performance models approximate perceptual, cognitive, and motor activities. They can support comparison of interaction techniques, but their estimates are averages and should not replace user research. Individual differences, expertise, fatigue, disability, language, and context can substantially alter performance.

Fitts’s law is often applied to pointing tasks:

MT is predicted movement time, D is the distance to the target, W is the effective target width in the direction of movement, and a and b are empirically estimated constants for a particular device and population. The relationship assumes a pointing task with reasonably consistent movement conditions. Larger, closer targets generally require less time, which supports designing sufficiently large touch targets and placing frequent actions conveniently.

2.5 Distributed cognition and activity theory

Distributed cognition treats cognition as distributed across people, artefacts, representations, and environments. A cockpit display, checklist, and crew collectively support navigation; no single individual holds all relevant information. Activity theory similarly examines motives, tools, rules, communities, roles, and division of labour.

These perspectives are especially useful for enterprise systems, healthcare, education, and safety-critical environments. They prevent designers from focusing narrowly on an isolated screen when failures arise from workflow, policy, coordination, or organisational structure.

2.6 Ecological and embodied interaction

Embodied interaction recognises that people interact through bodies, physical surroundings, gestures, voice, and social practices. Wearables, spatial computing, robotics, and Internet-of-Things systems make this perspective increasingly important. The design must address physical comfort, movement, privacy, environmental conditions, and the social meaning of visible or audible actions.

3. Human-Centred Design Process

Human-centred design is iterative. It begins with understanding people and their contexts, translates findings into requirements, develops alternatives, evaluates them, and repeats the cycle. It is not a linear sequence in which research ends once coding begins.

Figure: Human-centred design as an iterative cycle rather than a one-time phase.

3.1 User and context research

Common methods include interviews, observation, contextual inquiry, diary studies, surveys, document analysis, workshops, and field studies. Each method produces different evidence. Interviews reveal perceptions and goals; observation reveals workarounds and tacit practices; surveys support broader measurement but may lack depth.

Research should identify primary users, secondary users, exceptional situations, accessibility needs, goals, tasks, constraints, technologies, and success criteria. Personas can synthesise research into representative user models, while scenarios describe users pursuing goals in context. Personas should be evidence-based and should not stereotype or conceal important diversity.

3.2 Requirements and journey analysis

Functional requirements specify what a system does. Interaction requirements specify how users accomplish goals. Accessibility requirements specify support for alternative input, output, communication, and cognition. Non-functional requirements include security, privacy, performance, reliability, and maintainability.

Journey maps reveal stages before, during, and after interaction, including pain points and emotional responses. Task analysis decomposes activities into goals, subtasks, decisions, objects, and information requirements. Hierarchical task analysis is useful for complex workflows, while cognitive task analysis examines knowledge and decisions in expert work.

3.3 Prototyping

Sketches and paper prototypes are inexpensive and encourage exploration. Wireframes focus on structure; interactive prototypes represent navigation and behaviour; high-fidelity prototypes approximate appearance and interaction. Prototypes should be chosen according to the question being investigated. A visually polished prototype is not automatically a better research instrument.

Design alternatives should be compared against explicit criteria such as task success, accessibility, safety, privacy, implementation cost, and learnability. Participatory design involves users as contributors, especially groups whose needs have historically been overlooked.

4. Evaluation and Evidence

4.1 Usability testing

In usability testing, representative participants attempt realistic tasks while researchers observe performance and collect qualitative and quantitative evidence. A protocol should define recruitment criteria, tasks, environment, consent procedures, moderator behaviour, data recording, and stopping rules.

Important measures include completion, time, errors, assistance requests, satisfaction, and confidence. A task success definition must distinguish partial completion from complete, correct, and safe completion. Small formative studies can reveal severe problems, while larger studies support more stable estimates.

A confidence interval for a proportion can be estimated using more advanced statistical methods, but simple percentages should not be presented as universally precise when sample sizes are small. Researchers must avoid overgeneralising from convenience samples.

4.2 Inspection methods

Heuristic evaluation involves trained evaluators examining an interface against principles such as visibility of system status, match with the real world, user control, consistency, error prevention, recognition rather than recall, flexibility, minimalist design, useful error recovery, and documentation.

Cognitive walkthroughs focus on learnability by asking, for each step: Will the user try to achieve the correct effect? Will the user notice the correct action? Will the user associate it with the desired outcome? Will feedback reveal progress?

Inspection is efficient but may miss problems arising only in real contexts or for particular disability groups. It should complement, not replace, user involvement.

4.3 Analytics and A/B testing

Interaction logs can reveal abandonment, repeated errors, search reformulation, and navigation paths. Analytics must be interpreted cautiously because a metric is not an explanation. A reduced time on page could indicate improved efficiency or premature abandonment.

A/B testing compares alternatives under defined conditions. Randomisation, stable exposure, appropriate outcome measures, privacy protection, and sufficient sample size are essential. Statistical significance does not guarantee practical significance, ethical acceptability, or accessibility for minority users.

5. Accessible and Inclusive Design

5.1 The disability interaction

Disability is shaped by the interaction between a person and barriers in the environment. A person with low vision may experience no barrier when information is available in a well-structured, scalable format, but may be excluded by an image-only interface. This social and interactional perspective shifts attention from “fixing” individuals to removing design barriers.

Accessibility needs may involve:

• Vision: screen-reader compatibility, scalable text, contrast, non-colour cues, and meaningful structure.
• Hearing: captions, transcripts, visual alerts, and text alternatives.
• Mobility: keyboard access, adequate target sizes, timing tolerance, and compatibility with alternative input devices.
• Cognition and learning: clear language, predictable navigation, error prevention, adjustable complexity, and memory support.
• Speech and communication: alternatives to speech-only interaction and tolerance for varied speech patterns.

Disability is often situational. Noise can create hearing-related barriers; bright sunlight can create visual barriers; holding a child can create motor constraints. Designing for disability often improves usability for everyone.

5.2 The POUR principles

The Web Content Accessibility Guidelines (WCAG) organise accessibility around four principles:

1. Perceivable: Information and controls must be available through more than one sensory channel where necessary. Examples include text alternatives, captions, adaptable presentation, and sufficient contrast.
2. Operable: Users must be able to operate controls through available input methods. Keyboard access, adequate time, navigable focus, and avoidance of seizure-inducing content are important.
3. Understandable: Information and operation should be clear, predictable, and tolerant of errors. Labels, instructions, consistent navigation, and useful validation support this principle.
4. Robust: Content should work with current and future user agents, assistive technologies, and varied platforms. Semantic HTML and standards-based interfaces improve robustness.

Conformance levels and legal obligations vary by jurisdiction and procurement context. WCAG provides an important technical reference, but conformance is not identical to a complete accessibility guarantee.

5.3 Practical accessibility techniques

Use semantic headings in logical order, descriptive link text, correctly labelled form controls, keyboard-visible focus, and accessible names for controls. Do not communicate meaning through colour alone. Provide captions for prerecorded and live media where appropriate, transcripts, meaningful alternative text, and error messages linked to the relevant fields.

A decorative image may have an empty alternative-text value, whereas an informative image requires a concise description of its purpose. Complex charts may require a textual summary and access to the underlying data. Dynamic interfaces should expose state changes to assistive technologies without causing unexpected focus movement.

Accessibility testing should combine automated tools, manual keyboard testing, screen-reader testing, zoom and reflow testing, colour and contrast checks, and testing with disabled users. Automated tools detect only a subset of accessibility defects.

5.4 Accessibility as a life-cycle concern

Accessibility should appear in procurement criteria, user research, architecture, component libraries, coding standards, quality assurance, release gates, training, support, and maintenance. Retrofitting is often expensive because inaccessible assumptions become embedded in content, data models, and workflows.

An accessibility statement should describe supported features, known limitations, contact routes, and remediation plans. Organisations should assign responsibility and budget rather than treating accessibility as voluntary goodwill.

6. Ethics, Privacy, Safety, and Governance

HCI decisions allocate attention, authority, visibility, and risk. Dark patterns manipulate users through hidden costs, confirmshaming, difficult cancellation, deceptive defaults, or obstructive consent flows. Persuasive design may support beneficial habits, but it becomes ethically problematic when it undermines informed choice.

Privacy-sensitive design minimises unnecessary collection, communicates data practices clearly, supports meaningful consent, limits retention, and protects data throughout its life cycle. Notice alone is insufficient if users cannot realistically understand or control the practice.

Safety-critical interfaces must prevent catastrophic errors, make system state visible, support recovery, and avoid ambiguous alarms. Designers should analyse foreseeable misuse, near misses, and organisational pressures. A system that technically allows an action may still be unsafe if its consequences are difficult to perceive.

Artificial intelligence introduces additional HCI concerns: explainability, uncertainty communication, automation bias, overreliance, bias, contestability, and accessibility of AI outputs. An AI assistant should distinguish generated content from verified information, communicate limitations, preserve human control, and provide accessible alternatives. Voice systems should not become the only route to essential services because speech recognition varies across accents, languages, and disabilities.

7. Professional and Managerial Implications

HCI is a cross-functional responsibility. Product managers define outcomes and prioritise research; UX researchers investigate behaviour; interaction designers create flows and prototypes; visual and content designers communicate meaning; software engineers implement semantics and states; accessibility specialists test barriers; security and legal teams assess risk.

Managers should treat usability and accessibility as quality, risk, and equity concerns rather than cosmetic enhancements. Useful governance practices include accessibility acceptance criteria, design reviews, representative recruitment, defect severity classification, user research repositories, and post-release monitoring.

Trade-offs are inevitable. A highly configurable system may increase flexibility but also complexity. Strong security controls may introduce friction, while frictionless authentication may increase risk. The appropriate approach is not to eliminate trade-offs but to make them explicit, test them with affected users, and justify decisions against organisational and social goals.

8. Illustrative Case: Accessible Public Benefits Portal

Background

Consider a fictional municipal benefits portal through which residents apply for housing and income support. The original portal was designed primarily for desktop users and required long forms, timed sessions, scanned documents, and mouse-based date pickers.

Problem

Completion rates were low. Applicants using screen readers could not identify form errors, keyboard users became trapped in modal dialogs, and people with cognitive disabilities struggled to understand eligibility questions. Mobile users on unstable networks lost progress. Call-centre staff received repeated requests for assistance, increasing operational costs and delaying benefits.

Analysis

A research team used interviews, observation at community centres, support-call analysis, keyboard testing, screen-reader testing, and task-based usability sessions. The team found that the problem was not merely visual design. Policy language was difficult, the workflow did not match how applicants gathered documents, and error messages described technical validation rather than corrective action.

The team mapped the end-to-end journey and identified four high-risk points: determining eligibility, preparing evidence, completing the form, and reviewing submission status. Disabled residents and support workers participated in design workshops. Privacy requirements were included because applications contained sensitive personal information.

Approach and solution

The redesigned service used plain-language questions, progressive disclosure, a save-and-return function, persistent progress information, accessible names and descriptions, keyboard-operable controls, semantic headings, error summaries linked to fields, and alternatives to uploading scanned documents. The service provided captions and transcripts for explanatory media and allowed applicants to request human assistance without abandoning the digital process.

Testing was conducted with disabled and non-disabled participants across desktop and mobile conditions. Automated scanning was used for early detection, but manual and assistive-technology testing identified the most serious issues. The team measured complete task success, time, errors, assistance requests, and confidence, while monitoring privacy and security.

Outcome

In the illustrative evaluation, more participants completed applications without assistance, fewer users abandoned the process, and call-centre staff reported fewer preventable queries. The most important improvement was not a single interface component but alignment among policy language, workflow, accessibility, technical resilience, and support processes.

Learning points

1. Accessibility problems often originate in service design and policy, not only in front-end code.
2. Disabled users must participate in research and evaluation.
3. Automated compliance checks are useful but incomplete.
4. Saving progress and providing recovery can be as important as visual presentation.
5. Accessibility, privacy, usability, and operational efficiency can reinforce one another.

9. Challenges and Limitations

No single model captures all human interaction. Cognitive theories may underrepresent social and cultural meaning; performance laws may overstate predictability; personas may simplify diversity; analytics may obscure exclusion; and conformance checklists may encourage minimum compliance rather than genuine inclusion.

Representative research can be expensive and difficult when participants require interpreters, accessible transport, assistive technology, or additional time. Researchers must budget for these needs and avoid treating them as methodological inconveniences. Confidentiality is especially important when studying health, disability, employment, or financial information.

Global products face linguistic, cultural, infrastructural, and legal variation. A design that is accessible on a high-speed network may fail in regions with intermittent connectivity. Inclusive design therefore requires attention to localisation, low-bandwidth operation, device diversity, literacy, and local practices.

10. Contemporary Directions and Best Practices

Emerging HCI includes multimodal interaction, conversational systems, extended reality, affective computing, brain–computer interfaces, autonomous agents, and ubiquitous computing. These technologies create opportunities but also introduce new accessibility and governance questions. Multimodal systems should provide equivalent alternatives rather than assuming that vision, hearing, speech, gesture, or touch is always available.

Effective practice can be summarised as follows:

• Study real users, tasks, and contexts before fixing a solution.
• Make accessibility a requirement, not a late audit.
• Prefer semantic, interoperable, standards-based implementation.
• Design visible status, clear feedback, error prevention, and recovery.
• Support keyboard, touch, voice, screen readers, zoom, captions, and alternative input where relevant.
• Test with disabled users and assistive technologies.
• Measure outcomes, not only opinions or compliance scores.
• Protect privacy and avoid manipulative interaction patterns.
• Document limitations and maintain accessibility after release.
• Treat users as partners in design rather than as obstacles to delivery.

Chapter Summary

Human–Computer Interaction studies the relationship among people, technologies, tasks, and contexts. Usability concerns effectiveness, efficiency, and satisfaction, whereas user experience also includes emotion, trust, meaning, and the broader temporal experience of use. Accessibility and inclusive design address human diversity and remove barriers affecting perception, operation, understanding, and compatibility.

The chapter examined mental models, Norman’s action cycle, distributed cognition, embodied interaction, and Fitts’s law. It presented human-centred design as an iterative process involving contextual research, requirements, prototyping, and evaluation. Usability testing, heuristic evaluation, cognitive walkthroughs, analytics, and A/B testing provide complementary evidence and must be interpreted critically.

Accessible design requires perceivable, operable, understandable, and robust systems. It involves semantic implementation, alternatives to sensory channels, keyboard and assistive-technology support, clear error handling, and participation by disabled users. Ethical HCI also addresses privacy, safety, dark patterns, AI, bias, human control, and governance. The public-benefits case demonstrated that accessibility is a service-wide concern involving policy, workflow, technology, and support.

Key Terms

HCI: The interdisciplinary study of interaction between people and computing systems.

Usability: The extent to which specified users achieve goals effectively, efficiently, and satisfactorily in context.

User experience: The broader cognitive, emotional, social, and practical experience of using a product or service.

Accessibility: The extent to which people with diverse abilities can use a product, service, or environment.

Inclusive design: Design that intentionally accommodates human diversity from the outset.

Affordance: A possible action enabled by an object or interface.

Signifier: A perceptible cue indicating how an element can be used.

Feedback: Information communicating the result or status of an action.

Mental model: A user’s understanding of how a system operates.

Conceptual model: The explanation of system operation communicated by a design.

Context of use: The physical, social, organisational, technical, and temporal conditions of interaction.

Human-centred design: An iterative approach grounded in users, goals, and contexts.

Persona: An evidence-based representation of a user group.

Prototype: A representation used to explore or evaluate a design.

Heuristic evaluation: Expert inspection of an interface against recognised usability principles.

Assistive technology: Hardware or software enabling access for people with disabilities.

Semantic structure: Machine-readable meaning conveyed through appropriate elements and relationships.

Dark pattern: A manipulative interface practice that undermines informed user choice.

Distributed cognition: A view of cognition as distributed across people, tools, representations, and environments.

POUR: The accessibility principles of perceivable, operable, understandable, and robust.

Review Questions

Short Answer Questions

1. Distinguish usability from user experience.
2. What is the difference between an affordance and a signifier?
3. State the four POUR principles of accessible design.
4. Why should automated accessibility testing be supplemented by manual testing?
5. Define a mental model and explain its importance in interface design.

Long Answer Questions

1. Explain the human-centred design cycle and discuss how research, prototyping, and evaluation inform one another.
2. Compare heuristic evaluation, cognitive walkthroughs, and usability testing in terms of purpose, strengths, and limitations.
3. Discuss how cognitive, distributed, and embodied perspectives provide different explanations of human–computer interaction.
4. Explain how accessibility should be integrated across the software development life cycle.
5. Analyse the ethical responsibilities of designers developing AI-assisted interfaces.

Analytical / Application Questions

1. A university registration system works well for mouse users but traps keyboard users in dialog boxes and provides colour-only error indicators. Analyse the barriers and propose a prioritised remediation plan.
2. Design an evaluation study for a mobile health application used by older adults and people with low vision. Specify participants, tasks, measures, ethical safeguards, and limitations.
3. A product team reports that a redesigned checkout page reduced average task time but increased refund requests. Interpret this result using HCI concepts and recommend further investigation.

Multiple Choice Questions with Answers

Question 1

Which statement best distinguishes accessibility from usability?

A. Accessibility concerns only visual design, whereas usability concerns only software performance.

B. Accessibility addresses use by people with diverse abilities, while usability concerns effective, efficient, and satisfactory use in context.

C. Accessibility is measured only after deployment, whereas usability is measured only before coding.

D. Accessibility and usability are identical terms with no meaningful distinction.

Correct Answer: B. Accessibility addresses use by people with diverse abilities, while usability concerns effective, efficient, and satisfactory use in context.

Question 2

In the task-completion formula, what does the denominator represent?

A. The number of successfully completed tasks

B. The average time per task

C. The total number of task attempts

D. The number of interface errors

Correct Answer: C. The total number of task attempts

Question 3

Which POUR principle requires information and controls to be available through suitable sensory channels?

A. Perceivable

B. Operable

C. Understandable

D. Robust

Correct Answer: A. Perceivable

Question 4

What is the primary purpose of a cognitive walkthrough?

A. To estimate server response time

B. To assess learnability for users performing tasks

C. To measure colour contrast automatically

D. To calculate the financial return of a product

Correct Answer: B. To assess learnability for users performing tasks

Question 5

According to Fitts’s law, which change generally reduces predicted pointing time?

A. Increasing the distance to the target

B. Reducing the target width

C. Increasing the target width

D. Removing visual feedback

Correct Answer: C. Increasing the target width

Question 6

Which practice best supports robust accessibility?

A. Using images of text for all headings

B. Relying exclusively on colour to communicate status

C. Using semantic structure and standards-based implementation

D. Disabling keyboard focus to simplify navigation

Correct Answer: C. Using semantic structure and standards-based implementation

Question 7

Why are disabled users important participants in accessibility evaluation?

A. They eliminate the need for all other forms of testing.

B. They can reveal barriers that automated tools and non-disabled evaluators may miss.

C. They are required to approve every software release legally.

D. They provide only aesthetic feedback about colour and typography.

Correct Answer: B. They can reveal barriers that automated tools and non-disabled evaluators may miss.

Question 8

Which example is most clearly a dark pattern?

A. A clearly labelled cancel button placed beside a confirmation button

B. A form that identifies errors and explains how to correct them

C. A subscription service that makes cancellation intentionally confusing and difficult

D. A progress indicator showing the current stage of a workflow

Correct Answer: C. A subscription service that makes cancellation intentionally confusing and difficult

Question 9

What does distributed cognition emphasise?

A. That cognition occurs only inside an individual user’s brain

B. That cognition can be distributed across people, tools, representations, and environments

C. That interfaces should remove all physical artefacts

D. That usability can be measured without observing context

Correct Answer: B. That cognition can be distributed across people, tools, representations, and environments

Question 10

A colour-only warning is inaccessible primarily because it fails to provide what?

A. A non-colour cue or alternative representation of meaning

B. A larger database index

C. A faster processor

D. A longer software licence

Correct Answer: A. A non-colour cue or alternative representation of meaning