Abstract
Humans are experts at designing and utilizing unique tools to accomplish various tasks, like wielding an axe to chop wood. Humans are also capable of using different tools to accomplish opposing motor tasks simultaneously (using a fork and knife to cut meat). While a lot is known about motor adaptation with changed visual feedback of the hand, we rarely consider how we adapt tool use in novel situations requiring different movement patterns. Here we test whether having two tools that require different movements to accomplish a similar goal would serve as sufficient cues that allow dual tool-use adaptation, akin to lead-in movements in dual motor adaptations. We ran an immersive Virtual Reality experiment where 40 participants used 2 different tools to launch a ball towards a target; a paddle (forward motion) or slingshot (backward motion). Participants swapped between tools every 8 trials. After a familiarization phase, we added visually opposite perturbations to the ball after it was launched from each tool (30 degrees clockwise or counterclockwise rotation). Participants in a control group learned to use each tool with perturbed ball movements separately. We found that participants could form distinct motor memories for both tools, adapting their movements to the opposing perturbations. However, errors following exposure to the perturbation remained above baseline, suggesting that complete dual motor adaptation learning did not occur. These findings suggest separate motor memories form more slowly in dual-tool adaptation.