Figure 1.

Experimental paradigm and conditions. A, Schematic representation of the movement of the hand and of the relevant sensory events occurring during each trial: all events are aligned in time. Each trial starts with the presentation of an acoustic tone (start signal); after a variable pause a second tone is presented (go signal) that instructs participants to move their right hand as fast as possible. The first pair of tactile taps (test) is presented at variable delays from the go signal, with a fixed onset asynchrony of 150 ms. After 2 s from test presentation the second pair of taps is presented (probe) with a variable temporal separation. B, Experimental conditions. The movement condition implies the movement of the right hand; tactile stimulations are delivered either to the right moving hand or to the left static hand with equal probability across trials. The isometric contraction condition implies the generation of a transient lateral force against a block, with no movement execution; tactile stimulation is always delivered to the right contracting hand.