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.

How do humans walk without falling? Stable gait requires control of the body’s center of mass in relation to its base of support. The goal is of course to limit, or recover, from small perturbations that occur during every step. Passive walkers may have some stability, but in real-life conditions active muscle control is paramount. Different muscles con-trolled by different parts of the central nervous system work to adapt the position of the base of support or to de-/accelerate the body center of mass. Building on my research on kinematic measures and neural correlates of gait stability, I here hypothesize that sever-al distinct phases of the gait cycle require active control. To test this I propose to 1. validate and progress phase-dependent mathematical measures of gait stability, and use these to establish phase-dependency of gait control. 2. identify movement strategies and their neural implementation used for gait stability via kinematic, electromyographic, and electro-encephalographic recordings; 3. detail cortical contributions in control of gait stability using transcranial magnetic stimulation. With this project I will be the first to study strategies, muscles, and cortical areas involved in control of gait stability in an integrated manner. I consider this integrated approach mandatory for unravelling the mechanisms underpinning control of stability in human walking.

We aim at validating the hypothesis that the human central nervous system (CNS) does use a predictive internal model in addition to sensory cues for the control of posture, utilizing an error signal resulting in sickness. To distinguish direct sensory effects from effects caused by internal (cognitive) sources we will measure postural stability and motion sickness symptoms using both exogenous (sensory) and endogenous (cognitive) interventions.

We believe the decisions we make result from careful thought processes. Yet our body is needed for turning these decisions into actions. Can it be that our motor system is also driving the decisions we make? The researchers will investigate to what extent the effort to move influences perceptual decision-making. In a series of behavioural experiments, they will systematically explore whether required muscle force, reaching distance, and handedness lead to a bias in selected choices. This approach may ultimately lead to a paradigm shift in cognitive psychology regarding the factors that contribute to decision-making behaviour in health and pathology.