Affordances

"term that refers to the properties of objects -- what sorts of operations and manipulations can be done to a particular object" (D. A. Norman 1988, The Psychology of everyday things).

A door affords opening
A chair affords support

"perceived affordance": the extent to which objects suggest their affordance.

The image shows the affordances of door handles and scroll bars. The perceived performance of some elements is better than that of other elements.