SUS: A System Unusable for Twenty Percent of the Population

Key Insights

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  Screen readers allow users to navigate web pages quickly by jumping through well-structured headings and content.

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  Low vision users often rely on system-wide screen magnification and color inversion settings to reduce eye strain.

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  Alternative navigation methods like head mice and voice dictation are selected based on task and user condition, not used exclusively.

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  Traditional lab-based usability research often prioritizes convenience over real assistive technology configurations, leading to inaccurate results.

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  Assistive technology users rarely use default settings; they extensively customize tools over time for optimal use.

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  The System Usability Scale (SUS) includes questions that confuse assistive technology users and do not capture their true experience.

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  Fable’s Accessible Usability Scale adapts SUS questions to better reflect the experience of assistive technology users.

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  Initial data shows screen reader users report significantly lower usability scores (mid-50s) compared to screen magnification users (low 60s).

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  Users’ lowered expectations after years of experience may mask the true severity of usability issues in assistive technology contexts.

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  Measuring accessibility usability accurately enables benchmarking and progress in improving digital products for all users.

Notable Quotes