006 Affordance

The physical characteristics of a thing influence its function and use.

• The form of a thing makes it better suited for some functions than others. For example, wheels afford rolling, and negatively afford being stationary.

• The form of a thing makes it better suited for some interactions than others. For example, buttons afford pushing, and negatively afford pulling.

• When affordances are good, things perform efficiently and are intuitive to use. When affordances are bad, things perform poorly and are hard to use.

• Design things to afford proper use, and to negatively afford improper use. When affordances are correctly applied, it will seem inconceivable that a thing can function or be used otherwise.

See Also Constraint • Desire Line • Mapping • Nudge

The push action required to open the left door conflicts with the “pull” affordance of the handle. The sign is a poor fix because it will usually be read after people pull the handle. By replacing the handle with a flat plate, the conflict is eliminated and the sign becomes unnecessary. The “push” affordance of the plate eliminates the possibility of error or confusion.