Figure 1.
Graphical formula illustrating the calculation of the OVERLAP between the play faces emitted by the subjects A and B. (tA1 = exact time of the end of PF/FPF by A; tB1 = exact time of the end of PF/FPF by B; tA0 = exact time of the beginning of PF/FPF by A; tB0 = exact time of the beginning of PF/FPF by B). The mathematical symbol ∩ indicates the intersection of 2 groups of data which corresponds to the time lag in common to the durations of the 2 facial expressions (tA1 − tB0). The mathematical symbol ∪ indicates the union of 2 groups of data corresponding to the time lag starting from the first frame showing the separation of the inferior from the superior lip of the subject A (tA0) to the first frame showing the 2 lips closed of the subject B (tB1). The calculation is applicable both when the PF/FPF of the trigger and responder overlap with each other and when player A’s PF/FPF ends later than player B’s PF/FPF ends (i.e., when the events occur in the following order: Player A’s PF/FPF onset → Player B’s PF/FPF onset → Player B’s PF/FPF offset → Player A’s PF/FPF offset).