Tolerance for Error
The Basics
The design minimizes hazards and the adverse consequences of accidental or unintended actions.
Guidelines
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Arrange elements to minimize hazards and errors: most used elements, most accessible; hazardous elements eliminated, isolated, or shielded.
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Provide warnings of hazards and errors.
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Provide fail-safe features.
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Discourage unconscious action in tasks that require vigilance.
In Depth
The image to the left is a poster illustrating an example opposing Tolerance for Error. The fire hydrant was placed in the middle of the sidewalk, which obstructs the path acting as an obstacle. People can run into it and injure themselves as it is in an unexpected place.
Examples
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Double-cut car keys have a high tolerance for error because user can insert the key with either side facing up. Regular car keys can only be inserted with one side up, having a lower tolerance for error.
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'Undo’ buttons allow users to correct mistakes, which increases the tolerance for error as mistakes aren't permanent.