Concurrent sensorimotor adaptation for different delays measured via a tapping task

Abstract

Perception of temporal synchrony between one’s own action and the sensory feedback of that action is quite flexible (Heron et al., 2009; Keetels and Vroomen, 2012; Stekelenburg et al., 2011; Stetson et al., 2006; Sugano et al., 2010, 2012). We examined whether concurrent sensory-motor temporal recalibration to different lags is possible for the left and right hand. During exposure, participants tapped their left and right index fingers in alternating fashion while each tap induced an auditory feedback signal (a short click sound). One hand was exposed to a long delay between the tap and the sound (∼150 ms), while the other hand was exposed to a subjective no-delay (∼50 ms) (‘adaptation’). After the adaptation, participants then performed a synchronous tapping task (‘post-test’) in which they tried to tap in synchrony with pacer tones presented at a constant inter-stimulus interval (ISI = 1000 ms). The results showed that the hand that was exposed to the delayed sound corrected for this delay by tapping earlier (a larger anticipation error) than the no-delayed hand. This temporal recalibration of the delayed hand occurred faster and was more complete (∼40%) if the two hands were exposed to the same rather than different delays (∼20%). This indicates that there is a central and a motor-specific component in motor-sensory temporal recalibration. Tapping in synchrony with a pacing signal is thus a sensitive measure of temporal recalibration with central and motor-specific components.