In Ngai’s coupling model, the relaxation rate of bulk amorphous polymers has a power law time dependence which can be measured by isothermal depolarization. We propose a method by which the time needed for one experiment is considerably shortened without loss of information. At temperatures below and above the liquid glass transition we have previously modified Ngai’s model by introducing a parameter t’ which replaces the physical time, while the other parameters of the model are constant. The above experimental method can be used to probe the hypothesis. This is illustrated for an amorphous poly(ethyleneterephtalate) sample studied below T-g. Above T-g the thermally stimulated depolarization current was analyzed for polystyrene. At the alpha-beta bifurcation temperature it appears that t’ = t.