To the end! Distribution of attention along a tool in peri- and extrapersonal space.

This study investigated the distribution of visual attention along a handheld tool depending on functional tool practice and its position in peripersonal or extrapersonal space. We created a tool with two functional parts placed at the tool's middle and end. Participants held the tool over a display such that functional parts were aligned with stimuli for a 50/50, go/no-go, target detection task. In Experiment 1, two groups with no prior tool experience performed the task either in peripersonal (near the body; tool held horizontally) or extrapersonal space (beyond arms' reach; tool held straight). Faster response times (RTs) were found for targets at the tool's end and for the peripersonal space group. In Experiment 2, participants used the tool's middle part in a hockey-like game prior to the task to assess functional practice effects. Again, faster RTs were found for targets at the tool's end and in peripersonal space. However, a tool part × space interaction suggested that mid-tool practice reduced performance differences between tool parts but only in peripersonal space. Experiment 3 confirmed the interaction effect when mid-tool practice was constrained to only extrapersonal space. Results suggest that visual attention is naturally drawn to the tool's end but that functional tool use can redistribute attention when positioned in peripersonal space. In extrapersonal space, no change was found suggesting that the extension of peripersonal space is not uniform in regards to visual attention and that the visual attention component is perhaps dissociable from the remapping of spatial representation by tools.