Figure 2. Rectified EMG recording of the superficial masseter. (a) Five min of recording, showing different behaviors. Indicated are the positions of the 20-second amplifications shown in b, c, and d. (b) Chewing behavior. (c) Silence period, with some small activity bursts. (d) Some grooming behavior. Scale of the vertical axes (0–100%) is identical in all plots. Broken lines indicate 5 and 50% of the peak activity (100%). Note that the distribution as shown in this Fig. is not typical for the total activity scheme during the entire day.