029 Constraint

Limiting the actions that can be performed to simplify use and prevent error.

• There are two types of constraints: physical and psychological.

• Physical constraints limit the range of possible actions by redirecting physical motion. The three kinds of physical constraints are paths, axes, and barriers.

• Psychological constraints limit the range of possible actions by leveraging the way people perceive and think. The three kinds of psychological constraints are symbols, conventions, and mappings.

• Use constraints to minimize errors. Use physical constraints to reduce unintentional inputs and prevent dangerous actions. Use psychological constraints to improve the clarity and intuitiveness of a design.

See Also Affordance • Confirmation ...

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