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. 2013 Nov 15;8(11):e78058. doi: 10.1371/journal.pone.0078058

Figure 9. Recorded head-angles.

Figure 9

A: Example course of the recorded head-angle over time of one animal at the optimal spatial frequency of 0.2 cyc/Inline graphic (A left) and a spatial frequency of 0.6 cyc/Inline graphic (A right), at which the human observer does not detect OMR behavior. Samples where the head angular velocity deviates less than Inline graphic = 9Inline graphic/s from the stimulus velocity of 12Inline graphic/s are highlighted in green. Significantly more frames fulfill this criterion and are hence automatically detected as stimulus tracking behavior at 0.2 cyc/Inline graphic than at 0.6 cyc/Inline graphic. B: Movement of the grating over time. C: Histogram of head velocities of all animals induced by the gratings with spatial frequencies of 0.2 cyc/Inline graphic (left) and 0.6 cyc/Inline graphic (right), both moving with 12Inline graphic/s. Positive numbers correspond to head-movements in the same direction as the stimulus moved, negative numbers to head-movements to the opposite direction. The green area indicates the region of head velocities that was tolerated as tracking behavior. To visualize the more strongly skewed distribution found for responses to 0.2 cyc/Inline graphic in contrast to 0.6 cyc/Inline graphic, head-movements that occurred in the range of tolerated speeds but in the wrong direction are highlighted by the red area.