Fig. 7.

Comparison of left and right wrist activity. In five additional subjects, we continuously measure both left and right wrist activity levels simultaneously for 1 week. (a) Distributions of left and right wrist activity for a typical subject. The subject is right-handed, and the activity level and variance of the right wrist is larger than that of the left wrist. As a result, compared to the left wrist, the right wrist has a smaller probability at small activity level, and a larger probability at large activity level. After the same rescaling as in Fig. 2(e)–(h), the distributions of the left wrist activity and the right wrist activity collapse onto the same curve. The functional form of this curve is the same as obtained in Fig. 2(e)–(h) and Fig. 3. (b) DFA results of left and right wrist activity fluctuations reveal practically identical power-law correlations—the same value of α. The smaller values of F(n) (vertical shift) for the left wrist are due to the smaller average activity level and variance of the left hand.