We present the application of 1D spatial and 2D spatial-spectral electron spin resonance imaging (ESRI) in order to deduce the intensity profile and the spatial variation of line shapes for nitroxides formed during accelerated UV irradiation and thermal degradation of poly(acrylonitrile-butadiene-styrene) (ABS) containing a hindered amine stabilizer (HAS). The detection of two dynamically different sites for the HAS-derived nitroxide radicals ("fast" and "slow" components) and the decrease of the relative intensity of the fast component with UV irradiation or heating time point to the butadiene-rich domains as the vulnerable site for degradation. Spatial variation of the nitroxide intensity and of the line shapes was detected in the UV-irradiated samples. The nitroxide signal is strong on the irradiated side, increases with time on the opposite side, and is very weak in the sample interior; these results were taken as evidence for diffusion-limited oxidation. By contrast, the radical concentration and the line shapes are spatially homogeneous in the polymer undergoing thermal degradation at 333 K. This study has demonstrated the potential of imaging methods based on ESR to provide details on polymer degradation and stabilization that cannot be deduced from properties averaged over the entire sample.