Validation of position estimation during sexual behavior.

A: An example of the estimated positions of body parts during sexual behavior. The corresponding movie is available as Movie S2. B: Cumulative frequency of occurrence of significant problems around mounting. Horizontal axis indicates the time from the onset of mounting. N: −2 sec from onset of the next mounting. C: The averaged errors of estimated positions for the head, neck, trunk, and hip of male and females around mounting. Exp 1: the experimenter 1; Exp 2: the experimenter 2; Com: the present system. Error bars: SD. D: An example of the time-course of parameters used for detecting mounting around an occurrence of a mount. Hip–hip dist.: distance between the hips; hip–trunk dist.: distance between the female hip and the male trunk; H. angle difference: angular difference between the horizontal direction of rats; male V. angle: vertical angle of the male rat; A: time period when the male rat mounted, as automatically detected by the 3D system; M: time period when the male rat mounted, as visually observed by the experimenter. E: An example chronogram for the head-head contact event (blue) and the male approach event (red) marked by the present system (Com) and 2 blind experimenters (Exp 1 and 2).