The effects of the kinetics of polarization switching in ferroelectrics, taking into account the spatio-temporal fluctuations of the polarization field, given by the Langevin and Fokker-Planck equations, are studied. A Fokker-Planck equation is derived, which describes the polarization reversal in terms of Fourier amplitudes. A monotone and stable exponential-type finite volume difference scheme is elaborated to solve this equation numerically in a spatially homogeneous case, where the equation is one-dimensional. The temporal behaviour of the polarization probability distribution is calculated in presence of a sinusoidal field and white noise. The resulting hysteresis of the mean polarization is discussed for different noise intensities.