How touch influences the visual selection of grasp points

As we reach to pick up an object, we typically select—through our sense of sight—appropriate surface locations on which to place our fingertips. These contact locations almost unfailingly secure the object within our grip. Presumably, we must have learnt the association between images of objects and successful grasp locations through experience. For instance, if we grasp a portion of an object that looks different from the rest, and the object slips out of our grip, we might learn to visually perceive these object locations as “slippery” to avoid grasping them in the future. Thus, physically executing grasp movements and touching objects with our fingertips must shape how we visually perceive and interpret graspable objects and their physical properties. In this talk, I will discuss a series of studies from our group in which we explore how humans visually select grasp locations, and how this selection process is refined by physically touching objects. In one set of experiments, we asked participants to report which of two competing grasps was best. We found that participants could determine grasp quality even without performing the grasp—perhaps through motor imagery—and further refined their understanding of how to correctly grasp an object through tactile/sensorimotor feedback. In a separate study, we observed that participants could visually assess whether a surface would feel slippery to the touch, and found that participants willingly adopted unusual grasp configurations to avoid these slippery surfaces. These studies showcase how tactile feedback influences our visual understanding of objects and their grasp-relevant properties.