A cross-modal interference effect in grasping objects

The aim of the present paper was to investigate how the kinematics of a hand reaching toward a visual target would be influenced by haptic and proprioceptive input from an unseen distractor actively graspedin the other, nonreaching hand. The main resultswere that the amplitude of maximum grip aperture was smaller and the time to maximum grip aperture was earlier when the distractor was smaller than the target.The interferenceeffect fromthe distractorwas similar for both hands as they reached. Furthermore, results from a vibrating-distractorcondition for passive tactile input revealedthat the interference effects were evident only when the distractor was actively grasped.We suggest that neural processing of proprioceptive and tactile information relevant to distractor size produced the observed interference effects.We also emphasize the importance of active manipulation of the distractor stimulus in eliciting such interference effects.