Figure 7
Grip forces (GF) applied during tracking. (A) Example for GF during tracking without visual manipulation (Normal condition). In this example the GF (grey line) is slightly leading the load force (LF, marked by a black line). (B) Example for GF during tracking under the Delay condition where the phase between GF and LF signals increase significantly. Visual manipulation seems to affect the synchronization between the two signals. (C) Group analysis of phase between GF and LF signals. During Normal tracking the GF led the LF (solid green bar). This lead is increased significantly while tracking the target under the Delay (solid red bar) or Mechanical (solid blue bar) conditions. Bars represent mean value across participants and error bars are 95% confidence intervals estimated using t-distribution. ***p < 0.001. (D) GF is synchronized with a LF signal (LF model) which is a combination of real inertial forces and virtual forces of the spring in the mechanical model using the same data of the example in (B). (E) Group analysis of phase between GF and LF model signals. Phase decreased and resembled the phase during the N condition when we added the virtual force produced by the spring to the actual load force under both the Delay condition (striped red bar) and the Mechanical condition (striped blue bar). Bars represent mean value across participants from groups 1 and 2 and error bars represent 95% confidence estimated using t-distribution. (F) Same as in (E) but for groups 3 and 4.
