A lightweight ontology formalising Gibson's notion of Affordance. Affordance Affordance An Affordance relation that associates a stereotyped situation, i.e. a Description, with a Task that can be executed in that situation. has affordance It associates a Task with its Affordance relations. It relates an affordance relation with the description of a situation in which the affordance holds. affords It associates an affordance relation with the task afforded. It defines when the task can be executed. has effect It associates a Task with the effect of its execution, i.e. a Description of a stereotyped situation.