On Stoffregen's Definition of Affordances

Stoffregen (2003) has proposed a formal definition of affordances as emergent or relational properties of animal-environment systems. This definition contrasts with Turvey's (1992) formal definition of affordances as properties of the environment. In this commentary, my purpose is not to take sides on this issue but instead to bring to light what I believe to be a crucial flaw in Stoffregen's definition. Specifically, I show that Stoffregen's definition places no constraint on which relational or emergent properties legitimately deserve to be counted as affordances, thus allowing any relational property that can be predicated of an animal-environment system to be considered as an affordance. As such, Stoffregen's definition lacks any substantive linkage to the "opportunity for action" notion that has accounted for the scientific utility of the concept to date, a linkage I suggest should be preserved in any definition of affordances.