SUS: A System Unusable for Twenty Percent of the Population

Key Insights

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  Screen readers require highly structured and semantically correct web content to enable efficient navigation for blind users.

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  Screen reader users often customize speed and voice settings to consume information at 400-800 words per minute, much faster than typical speech.

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  Alternative navigation devices, such as head mice and switch systems, rely on precise physical control and can be hindered by environmental factors like vibrations.

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  Current think-aloud usability testing methods create cognitive overload for assistive technology users, as they must manage device output, researcher communication, and narration simultaneously.

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  Travel and physical accessibility barriers severely limit the participation of people with disabilities in traditional usability labs.

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  Assistive technologies are highly personalized, so standard lab setups often fail to support users’ customized configurations, reducing test validity.

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  Standard System Usability Scale (SUS) questions inadequately capture the unique needs and experiences of assistive technology users.

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  Fable’s Accessible Usability Scale (AUS) adapts SUS questions to reflect assistive technology usage, improving relevance and accuracy.

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  Preliminary AUS results show screen reader users rate usability lower than magnification users, reflecting the greater complexity and demands of screen reader use.

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  Inclusive research requires adapting methods to account for varied assistive technologies, emphasizing flexibility and one-size-does-not-fit-all approaches.

Notable Quotes