Chatbot Accessibility Playbook

Recommendation 4.3.18:
Follow WCAG guidelines when applicable to the chatbot interface

Benefits Users

Icon for VisualIcon for AuditoryIcon for CognitiveIcon for SpeechIcon for PhysicalVisual | Auditory | Cognitive | Speech | Physical

Phase 1: Gather & Organize

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  • The WCAG document does not specifically address the wide range of cognitive abilities in target users. Latest recommendations from W3C’s Cognitive and Learning Disabilities Accessibility Task Force (COGA TF) have information explicitly directed at cognitive disabilities that can fill gaps in WCAG guidance. Ultimately, user tests will reveal how accessible the chatbot is.

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  • The table below matches recommendations from this playbook to the W3C WCAG and COGA recommendations to which they correspond. In most of these cases the W3C source gives explicit information such as user stories and techniques that directly address the recommendation from the playbook.
Recommendation WCAG Success Criteria COGA Design Patterns
4.3.1 Offer multi-modal interaction WCAG 2.5.6 Concurrent Input Mechanisms  
4.3.2 Support STT and TTS WCAG 1.2.2 Captions  
4.3.3 Support keyboard navigation WCAG 2.1.1 Keyboard  
4.3.4 Support screen readers WCAG 1.3.1 Info and Relationships  
4.3.5 Support zoom WCAG 1.4.4 Resize Text

WCAG 1.4.10 Reflow		  
4.3.6 Offer color contrast WCAG 1.4.3 Contrast (Minimum)  
4.3.7 Use legible fonts WCAG 1.4.8 Visual Presentation  
4.3.8 Consider font size WCAG 1.4.4 Resize Text  
4.3.9 Highlight visual focus WCAG 2.4.7 Focus Visible  
4.3.10 Consider chatbot size WCAG 1.4.8 Visual Presentation  
4.3.11 Minimize distraction WCAG 3.2.5 Change on Request COGA 4.6.1 Limit Interruptions
4.3.12 Distinguish senders   COGA 4.3.5 Break Media into Chunks
4.3.13 Label buttons   COGA 4.5.6 Use Clear Visible Labels
4.3.14 Accept varied language   COGA 4.5.4 Design Forms to Prevent Mistakes

COGA 4.5.8 Accept Different Input Formats
4.3.15 Allow user customization   COGA 4.9.4 Support a Personalized and Familiar Interface
4.3.16 Manage pacing WCAG 3.2.5 Change on Request COGA 4.5.1 Ensure Controls and Content Do Not Move Unexpectedly


Phase 2: Design & Implement

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  • When WCAG isn’t clear about chatbot features, go to users instead.

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  • When pacing chatbot messages in a sequence of multiple messages (4.3.21), refer to COGA Design Pattern 4.5.1, which suggests not moving content unless initiated by the user. To conform with the design pattern, consider waiting for the user to press a button to indicate they are done reading the current message before displaying the next one; or make sure the scrollable area does not move and interrupt the user’s reading as subsequent messages are received.


Phase 3: Test & Evaluate

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  • Did you review WCAG as you completed the Gather and Organize phase?

  • Did you revisit WCAG during the Design and Implement phase?

  • Did you test and evaluate the chatbot against WCAG standards for interface?

  • Is there a developer on the team with WCAG training or accessibility experience?