Tool-sensed object information effectively supports vision for multisensory grasping

Abstract

Tools enable humans to extend their sensing abilities beyond the natural limits of their hands, allowing them to sense objects as if they were using their hands directly. The similarities between tool-mediated and hand-based sensing entail the existence of comparable processes for integrating tool- and hand-sensed information with vision, raising the intriguing question of whether tools can support vision in bimanual object manipulations. Here we investigated this question by measuring participants performance while reaching for and grasping objects either held with a tool or with their hand. We found that tool-mediated sensing effectively supports vision in multisensory grasping. Even more intriguingly, tool-mediated sensing resembled hand-based sensing. In addition, by manipulating the object features (availability of position and size versus position only), we found that both tool- and hand-mediated action performance was not hindered by the absence of size information. Thus, integrating the tool-sensed position of the object with its vision is sufficient to promote a multisensory advantage in grasping. In sum, our findings indicate that multisensory integration mechanisms significantly improve grasping actions, fine-tuning contralateral hand movements even when object information is only indirectly sensed through the hand operating a tool. Significance statementTools allow extending the hands sensing capabilities beyond their anatomical limits. Here we show that object information sensed through a tool can guide bimanual object manipulations as effectively as when directly sensed by the hand. Both tool and hand sensing provide relevant object positional information that are merged with vision to improve action performance. Our findings provide evidence about the interchangeable use of tools and hands for skilled actions and open new perspectives for prosthetic applications and rehabilitative plans.