Efference Copy Signals Enhance Haptic Precision During Active Information Acquisition

Haptic perception arises from the integration of cutaneous and kinesthetic inputs (proprioceptive and efference copy signals), but the specific contributions of these signals remain debated. To dissociate their roles, we conducted a spatial frequency discrimination experiment with three conditions: active (free arm movement), passive-arm (motor-driven replay of active kinematics), and passive-stimulus (stationary arm with probe motion matched to active kinematics). We found lower just noticeable differences in the active condition relative to both passive conditions, with no difference between passive conditions, suggesting that the prediction of arm movement from the efference copy enhances perceptual precision during active sensing.