Severity of Accessibility Issues

Posted by Albert Gareev on Feb 10, 2016 | Categories: AccessibilityHeuristics


I’m exploring ways to better communicate impact of severity issues. Even the developers working on accessibility seem to look at it from “mechanical” or purely functional perspective.

The challenge is heightened because it’s hard, likely impossible, to make valid assumptions on kinds of special needs, skills and experience of the users with assistive technologies, domain and product, context of use, and so on. To address the challenge, I’m capitalizing on user persona exploration ideas. As an inspiration for severity definitions I’m taking “Taking Severity Seriously” article by Michael Bolton.

The following is a technical entry. It will evolve further.

All opinions are wanted and much appreciated.

General Considerations

Investigation and documentation of accessibility issues should address the following considerations.

Problem Statement

  • What task and purpose are impacted, in what user scenario?
  • What is the type of the impact: operation-input, operation-intake, user experience, emotions?
  • What is the cause of the impact: presence of anti-pattern, missing recommended pattern, or inconsistency criteria used (purpose, communication, claims, patterns, comparable features)

Affected Users

  • Who are the affected users, what are their special needs ? (vision, motion, hearing, cognitive, combinations)
  • What users’ needs are affected (Critical? Important? Casual? Negligible?)?
  • What is the affected platform/technology? (Browser, 3rd party technology used as google maps, PDF, MS Office Docs, other?)
  • What is the affected Assistive Technology? (Screen Reader, Magnifier, other?)
    • What’s the impact? (Parsing errors, keyboard conflict, other?)


  • Configuration (URL, Browser, Screen Reader, other)
  • Steps to follow
  • Data to input
  • Affected or affecting elements of the presentation (i.e. particular UI areas or controls)
  • Affected or affecting operations (input, reading, understanding, other?)


  • Another (working) configuration (Browser, Screen Reader, other)
  • Alternative workflow or navigation (steps, instructions). Think broader than functional workaround.

Severity Definitions

I propose severity of barriers described so that they’re telling the story of the impact on the users.

Barrier levels:

  • Highest: Blocking
  • High: Tripping
  • Low: Inconvenience
  • Non-barrier: Improvement


  • The barrier is so high that the impacted users would likely give up without achieving their purpose
  • It is caused by consistent unavailability of the function or persistent combination of barriers that require so much time/effort to overcome that the original purpose is virtually pointless
  • The functional purpose is among the primary services of the web site. For secondary services, lower the severity level
  • There are no workarounds, or the impacted users won’t be able to know about them or to use them effectively. If an acceptable workaround is available, lower the severity level
  • The barrier has a strong negative impact on the image and reputation of the company, or may  cause legal consequences
  • The barrier has a very high continuous effect on the User Experience
  • The barrier has a broad and consistent impact (even though the impact level might be not very high) within entire web site or majority of primary functions
  • The barrier may cause seizures or other significant effects on health


  • Color/Contrast of the screen effectively prevents the user from being able to distinguish the text
  • Missing or invalid textual descriptions for UI controls and non-text content make it extremely hard or impossible to figure out for screen reader users
  • Organization of the screen is based on visual characteristics (location, lines, decorative images, highlighting colors) – and has no accessible structure in auditory format
  • Complex (too busy or very non-linear) screens that increase cognitive load for understanding, remembering, and operation
  • Functions and screens that increase cognitive load for knowing and remembering how to operate, especially in case of lack of help, hints, cues, and reminders
  • Unsupported or mis-functioning support of keyboard operations, or keyboard conflicts between application and the browser and/or application and screen reader
  • Function or screen requires skills or knowledge above the level that the user may likely have


  • The barrier creates significant difficulties for achieving the purpose.
  • It is caused by partial or impacted availability of the function or persistent combination of barriers that require too much time/effort to overcome.
  • The functional purpose is among the primary services of the web site. For secondary services, lower the severity level.
  • To overcome the barrier the users have to restart, retry, guess, try different operations, ask for assistance, or remember the specific workaround.
  • The barrier has a notable negative impact on the image and reputation.
  • The barrier has a notable continuous effect on the User Experience.
  • The barrier has a broad and consistent impact (even though the impact level might be not very high) within a web page or workflow.


  • The barrier creates an insignificant impact for achieving the purpose.
  • The occurrence is rare.
  • There are simple and commonly known ways to overcome the barrier.



  • Access to function could be made easier or faster.
  • User Experience could be improved.
  • Inconsistency that is related to accessibility but does not create a real impact on users.


Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported
This work by Albert Gareev is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported.