It is known that the one-dimensional discrete maps having single-humpe
d nonlinear functions with the same order of maximum belong to a singl
e class that shows the universal behaviour of a cascade of period-doub
ling bifurcations from stability to chaos with the change of parameter
s. This paper concerns studies of the dynamics exhibited by some of th
ese simple one-dimensional maps under constant perturbations. We show
that the ''universality'' in their dynamics breaks down under constant
perturbations with the logistic map showing different dynamics compar
ed to the other maps. Thus these maps can be classified into two types
with respect to their response to constant perturbations. Unidimensio
nal discrete maps are interchangeably used as models for specific proc
esses in many disciplines due to the similarity in their dynamics. The
se results prove that the differences in their behaviour under perturb
ations need to be taken into consideration before using them for model
ling any real process.