Schematic representation of analytical method. (A) The amplitude values of EMG signal (e.g. RMS) were determined using a segmentation. Then, from frequency diagrams of each experimental situation (i-) the joint probability distribution (ii-) was determined. (B) A window (shaded vertical rectangle) of fixed width is slid over the EMG of middle deltoid and arm angular position (top trace). At each window position, the amplitude value of EMG signal and the average stimulus value are used to increment the appropriate entry in a co-occurrence matrix, which defines the joint probability distribution, P(s,r). The stimulus and response probability distributions (P(s) and P(r), respectively) are given by the marginal distributions of the co-occurrence matrix.