In this paper we consider a continuous version of cellular automata (fuzzy
CA) obtained by "fuzzification" of the disjunctive normal form which descri
bes the corresponding Boolean rule. We concentrate on fuzzy rule 90, whose
Boolean version deserves some attention for the complex patterns it generat
es. We Show that the behavior of fuzzy rule 90 is very simple, in that the
system always converges to a fixed point. In the case of finite support con
figurations, we also show aperiodicity of every temporal sequences, extendi
ng and complementing Jen's result on aperiodicity of Boolean rule 90. We fi
nally show and analyze the remarkable fact that, depending on the level of
slate-discreteness used to visualize the dynamics of fuzzy rule 90, the dis
play might show (after a transient) the well known complex Boolean behavior
instead of the (correct) convergence to a fixed point. The results of the
analysis lead not only to a caveat on the dangers of visualization, but als
o an unexpected explanation of the dynamics of Boolean rule 90. (C) 2000 El
sevier Science B.V. All rights reserved.