Finger force of exploratory movements is adapted to the compliance of deformable objects

In this experiment we investigated the influence of stimulus properties on exploratory movement parameters in active touch. More precisely, we investigated whether and to what extent variations in stimulus compliance influence the executed finger force and velocity of the exploratory movements. Therefore, we varied the compliance of silicon rubber stimuli with deformable surfaces. Participants freely explored pairwise presented stimuli with a bare finger, and were asked to select the softer one. We found that both exploratory force and velocity depended on the compliance of the stimulus. Our results suggest in particular that observers strategically adapt their maximum finger force to the expected softness of the stimulus.