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. Author manuscript; available in PMC: 2018 Feb 1.
Published in final edited form as: Exp Brain Res. 2016 Oct 26;235(2):481–496. doi: 10.1007/s00221-016-4809-z

Figure 9.

Figure 9

An illustration of the two components of the unintentional finger force changes using a two-finger task of producing a value of total force: F1 + F2 = FTOT. The solution space is shown as a line with negative slope, UCM1. The preferred sharing of FTOT between the two fingers is shown with the large black dot; it is assumed to correspond to a minimum of the cost function (the parabolic dashed line). If the subject performs this task with an unusual force combination (the open circle), the cost is higher (the dashed circle). After visual feedback has been turned off, (F1 + F2) will drift to lower values due to the assumed referent coordinate (RC) drift resulting in new solution spaces shown by thinned lines (UCM2 and UCM3). At the same time, a drift along UCM toward the bottom of the cost function will take place. The resultant drift is shown as the dashed line with the arrow.