Look What It Can Do: Tool Heads Prime Saccades

Tools are wielded by their handles, but a lot of information about their function comes from their heads (the action-ends). While hand motor responses are affected by the position of a tool’s handle, not much is known about what parts of a tool might affect eye gaze. Here weinvestigated whether eye saccadic movements are primed by tool handles, similar to handactions, or whether they are primed by tool heads (action-ends). We measured human saccadic reaction times while subjects were performing an attentional task. We found that saccadic reaction times were faster when performed to the side congruent with the tool head, even though “toolness” was irrelevant for the task. Our results show that heads are automatically processed by the visual system to orient eye movements, showing that eyes and hands are driven by distinct parts of manipulable objects and by the kinds of information these parts afford.