Apparatus, including: a mockup probe, having a distal end and a proximal end adapted to be held by a human operator. The apparatus further includes a mockup patient, simulating an actual patient, the mockup patient having an aperture allowing penetration of the distal end of the mockup probe into the mockup patient. The apparatus includes a force generator, coupled to the mockup probe so as to apply a force to the proximal end that can be felt by the human operator, and a system controller. The controller is configured to: track a location of the distal end during the penetration thereof into the mockup patient, access an indication of a value of contractility of a region of an organ of the actual patient corresponding to the location, and activate the force generator so that the force applied to the proximal end corresponds to the indication.