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. Author manuscript; available in PMC: 2011 Jan 9.
Published in final edited form as: Medicina (Kaunas). 2010;46(6):382–392.

Figure 4.

Figure 4

In a two-finger force production task, independent control of each finger leads to uncorrelated variance across repetitions (forming a circle, stars). Negative covariation of finger forces decreases the total force variance. B. Comparison of the VUCM and VORT components of variance in two hypothetical first responders performing infant CPR. The often used synergy index (e.g., [VUCM − VORT] / [(VUCM + VORT)/2]) would result in a larger value for responder #2 than responder #1, despite the fact that VORT, the only variance component that can lead to task level variance, is smaller for responder #1. The comparison emphasizes the need to examine each component of variance as well as any combined index when making conclusions about the usefulness of a synergy.