  We investigate the propagation of perturbations in Boolean networks by
evaluating the Derrida plot and modifications of it. We show that even small
Random Boolean Networks agree well with the predictions of the annealed
approximation, but non-random networks show a very different behaviour. We
focus on networks that were evolved for high dynamical robustness. The most
important conclusion is that the simple distinction between frozen, critical
and chaotic networks is no longer useful, since such evolved networks can
display properties of all three types of networks. Furthermore, we evaluate a
simplified empirical network and show how its specific state space properties
are reflected in the modified Derrida plots.
