It doesn't add up: Nested affordances for reaching are perceived as a complex particular.

In the Ecological Approach to Perception and Action, affordances are emergent, higher-order relationships in an animal-environment system. In addition, perceivers should perceive such relationships directly, rather than by combining lower-order constituents of the affordance, such as non-affordance properties of the animal or the environment. In the present study, we investigated whether this latter claim applied to perception of superordinate affordances - affordances that emerge from relations between lower-order affordances. We asked whether perception of a superordinate affordance for reaching by different means would be reducible to a combination of lower-order constituents of that affordance. Participants reported the maximum height that they would be able to reach with their arm alone versus with a hand-held tool. In both cases, reported judgments of maximum reaching height differed from an additive model in which values were computed from a combination of perceived lower-order constituents of the affordance. The results are consistent with the ecological claim that affordances are perceived, "as such," rather than being computed or inferred from constituent properties, even when those constituent properties are, themselves, affordances.