We present experimental results on the effect of periodic perturbations on a driven, dynamic system that is close to a period-doubling bifurcation. In the preceding article a scaling law for the change of stability of such a system was derived for the case where the perturbation frequency {omega}{sub {ital S}} is close to the resonances given by {omega}{sub {ital S}}/{omega}{sub {ital D}}=1/2, 3/2, 5/2,..., where {omega}{sub {ital D}} is the driving frequency. The theoretical prediction for the shift of the bifurcation point, {Delta}{mu}{sub {ital B}}, which we use as a measure of the stabilization, is {Delta}{mu}{sub {ital B}}{similar to}{ital A}{sub {ital S}}{sup 2}, where {ital A}{sub {ital S}} is the perturbation amplitude. We have investigated {Delta}{mu}{sub {ital B}} as a function of the frequency and the amplitude of the perturbation signal {Delta}{mu}{sub {ital B}}({omega}{sub {ital S}},{ital A}{sub {ital S}}) for a model system, the microwave-driven Josephson tunnel junction, and find reasonable agreement between the experimental results and the theory.