To handle an object we need to know what we are holding in our hand. When we move, rotate and squeeze what we have in our hand, the brain receives a stream of tactile inputs from locations distributed over the hand. To be able to process this haptic (i.e. touch) information in a useful way, information from the same object needs to be grouped together and segmented from other inputs. At the moment it is unknown how this crucial step of grouping of haptic information is performed. This project aims at determining the principles that govern this process. The proposed research will hereby significantly advance our current understanding of the haptic perceptual system. Moreover, this fundamental knowledge will potentially advance the development of technical applications such as tactile displays, robotic hands and prosthetics for patients with loss of hand function. The proposed research focuses on three possible main criteria for assigning parts to the same object: 1) parts of the same object move congruently, 2) forces can be transferred through an object and 3) constancy of material properties. Participants will be asked how many objects they perceive for surfaces touched with the fingers only as well as whole objects grasped in the hand. The experiments are designed such that they stay close to an ecological setting, while still allowing systematic variation of the possible grouping criteria. In this way, fundamental knowledge will be gained that is crucial for the advancement of our understanding of haptic perception in daily life.