Affordances and inertial constraints on tool use

Whether an object can be used to satisfy a given tool user's intention depe nds on, among other things, the object's inertial properties. Overcoming an object's rotational inertia is key in controlling a handheld object with r espect to a given intention. Manipulating an object by means of muscular ex ertion is the domain of dynamic touch. Thus, the affordances of a given obj ect as a tool should be perceivable by means of dynamic touch. In 3 experim ents, we investigated the inertial variables that support perception of 2 p otential affordances of handheld tools: hammer with- ability and poke,with- ability. The results suggest that ratings of hammers are dependent on the v olume of the inertial ellipsoid in such a way that supports the transferenc e of power to the struck surface. Ratings of pokers are dependent on the sa me quantity but in a way that supports controllability of the poking object . Additionally, results suggest that minimal experience in a given tool-usi ng task may "tune" tool users to the inertial properties required of a give n tool for a given function.