Background <p>Liquid crystal elastomers (LCEs) are polymers with nematic ordering that exhibit unique mechanical behaviors attributed to the interplay of network stretching and mesogen reorientation under loading. These competing viscoelastic mechanisms can lead to complex and heterogeneous local deformation response when exposed to an external stimulus such as light, thermal gradients, or applied stress.</p> Objective <p>This study developed stereo digital image correlation (stereo-DIC) measurements and analyses of strain fields in polydomain LCE specimens undergoing the polydomain-monodomain (P-M) transition to reveal deformation mechanisms.</p> Methods <p>Two macro-scale deformation modes probed the material response: quasi-static uniaxial extension and stepped stress-relaxation. Stereo-DIC tracked the full-field surface strain. A bespoke technique was developed consisting of a clustering algorithm to identify coherent strain clusters in the strain field at the maximum stress of the step loading and a stretched exponential model fit to the time-evolving strain response of the clusters and fitting to the stress relaxation response. This technique quantified differences in the viscoelasticity of the domains involved in the P-M transition.</p> Results <p>Strain maps during the hold period showed that strain heterogeneity increased with time. Strain in the majority of clusters either increased asymptotically or decreased asymptotically with time, leading to increasing strain heterogeneity. The characteristic relaxation times varied between the clusters and were different from that of the macroscopic stress response.</p> Conclusion <p>A new technique for quantifying surface strain clustering is available. Initial findings on LCEs suggest that the kinematics of viscous mesogen rotation depends on the local strain state.</p>