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An experimental approach for direct studies of the polarization reversal mechanism in thin film ferroelectric capacitors based on piezoresponse force microscopy (PFM) in conjunction with pulse switching capabilities is presented. Instant domain configurations developing in a 3x3 μm2 capacitor at different stages of the polarization reversal process have been registered using step-by-step switching and subsequent PFM imaging. The developed approach allows direct comparison of experimentally measured microscopic switching behavior with parameters used by phenomenological switching models. It has been found that in the low field regime (just above the threshold value) used in the present study, the mechanism of polarization reversal changes during the switching cycle from the initial nucleation-dominated process to the lateral domain expansion at the later stages. The classical nucleation model of Kolmogorov–Avrami–Ishibashi (KAI) provides reasonable approximation for the nucleation-dominated stage of switching but is inapplicable to the slow switching stage. It has been suggested that the switching dynamics can be approximated by averaging the KAI model over a broad distribution of switching times.