Abstract
Observers experience visual biases in the area around handheld tools. These visual biases may occur when active tool use leads an observer to incorporate a tool into the body schema. An alternate theory states, however, that the visual salience of a handheld tool may create an attentional prioritization that is not reliant on body-based representations. We tested these competing explanations of near-tool visual biases by asking participants to complete a target detection task in which targets could appear near or far from a tool positioned next to a display. In Experiment 1, before completing the target detection task, participants either 1) used a rake tool to retrieve objects, 2) held the rake without using it, or 3) saw, but never touched, the rake placed next to the display. Participants who used the rake and participants who merely held the rake were faster to detect targets appearing near the end of the rake than targets appearing on the opposite side of the display, but participants who only viewed the rake showed no such evidence of near-tool facilitation. In Experiment 2, participants used the rake to retrieve objects and then performed the target detection task under conditions in which they either could or could not see the rake next to the display. The magnitude of near-tool facilitation was reduced for participants who were unable to see the rake during the target detection task. In Experiment 3, participants performed the same target detection task while holding a complex magnetic tool next to the display; some participants first used the complex tool to retrieve objects while others passively held the tool. Both groups of participants showed near-tool facilitation on the target detection task. Taken together, these results suggest active use is unnecessary, but visual salience alone is not sufficient, to introduce near-tool visual biases.