The unique properties of the ferroelectric relaxors are thought to be due to compositional and charge disorder in these systems [1,2], which can manifest at atomic and mesoscopic length scales. However, little is known about polarization dynamics in the prototypical ferroelectric relaxor system (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) at the mesoscopic level. Here, we develop a multidimensional piezoresponse force microscopy (PFM) based technique  to study the voltage and time dependent response of the single crystal relaxor PMN-0.28PT. Measurements reveal that for small bias, there is little perturbation, but the relaxation increases for larger bias pulse amplitudes. Furthermore, mesoscale heterogeneity is evident in relaxation amplitudes, with two distinct amplitudes present. To gain insight into the disorder, the entire dataset was further analyzed by independent component analysis. These reveal the presence of a disorder component to the response, which is found to be inversely correlated to the piezoresponse at that area. The difference is postulated to arise from the mixture of rhombohedral and field-induced tetragonal phases present in the probed volume of the tip, which can vary spatially depending on local defects, chemical inhomogeneity and elastic clamping effects. These studies show the utility of PFM-based spectroscopies in combination with big-data style analyses in mapping the disorder that underpins functionality of the ferroelectric relaxors. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE (RKV, SVK). A portion of this research was conducted at and partially supported by (SJ, MO) the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. NBG acknowledges funding from the US national Science Foundation through grant # DMR-1255379. References 1. A. A. Bokov, Z. ï¿½G. Ye, J. Mater. Sci. 41, 31 (2006). 2. F. Jiang, S. Kojima, C. Zhao, C. Feng, Appl. Phys. Lett 79, 3938 (2001). 3. S. V. Kalinin, B. J. Rodriguez, J. Budai, S. Jesse, A. Morozovska, A. A. Bokov, Z.-G. Ye, Phys. Rev. B. 81, 064107 (2010).