Affordances and Inertial Constraints on Tool Use

Abstract

Whether an object can be used to satisfy a given tool user's intention depends on, among other things, the object's inertial properties. Overcoming an object's rotational inertia is key in controlling a handheld object with respect to a given intention. Manipulating an object by means of muscular exertion is the domain of dynamic touch. Thus, the affordances of a given object as a tool should be perceivable by means of dynamic touch. In 3 experiments, we investigated the inertial variables that support perception of 2 potential affordances of handheld tools: hammer-with-ability and poke-with-ability. The results suggest that ratings of hammers are dependent on the volume of the inertial ellipsoid in such a way that supports the transference of power to the struck surface. Ratings of pokers are dependent on the same quantity but in a way that supports controllability of the poking object. Additionally, results suggest that minimal experience in a given tool-using task may "tune" tool users to the inertial properties required of a given tool for a given function.