One of the most controversial dilemmas in virtual reality laparoscopic simulators design is the incorporation of force feedback (FF). This issue is approached with an experimental design in which surgeons assess the resistance against pulling of four different tissues, which are characterized with the acquisition of interaction forces. Comparing subjective assessments with objective force parameters we aim to determine the fidelity boundary beyond which no more realism is necessary in simulation. Interaction pulling forces of four tissues have been characterized, which can constitute a basis for requirements of a FF algorithm. Results have also led to the hypothesis that surgeons are able to differentiate tissues and perceive somesthesic information although resulting interaction forces are of the same magnitude than interferences like trocar friction.