Hierarchical Nesting of Affordances in a Tool Use Task

In studying the perception of affordances, researchers have typically identified a single affordance and designed experiments to evaluate the perception of that affordance. Yet in daily life, multiple affordances always exist. One consequence of this is that there may be higher order, means-ends relations between different affordances. In 4 experiments, we created situations in which lower order, subordinate affordances could affect the realization of higher order, superordinate affordances, and we asked whether participants were sensitive to these hierarchical, nested relations. Participants wielded tools that varied in length, mass, and mass distribution. In Experiments 1 and 2, we asked them to evaluate these tools in terms of their suitability for executing specific interactions with target objects (striking vs. poking) that were positioned at different distances. In Experiments 3 and 4, we asked participants to select rods and masses and then to assemble them into tools that could be used to execute specific interactions with target objects at different distances. The results were compatible with the hypothesis that participants were simultaneously sensitive to affordances for tool assembly and affordances for tool use. We argue that the nesting of affordances is characteristic of many situations in daily life and that, consequently, sensitivity to hierarchical, means-ends relations among affordances may be an essential characteristic of perceptually guided action.