Tests for the existence of directional coupling between two mutually coupled logistic maps, x and y, driven by another logistic map, z.

Panels A and C refer to the direction from x to y, and panels B and D refer to the direction from y to x. A and B show the results with the method proposed by Sugihara et al. [16], and C and D show the results with our method. See the caption of Fig 3 to interpret the results.