While the understandability of process models has been extensively investigated for different process modeling notations, it has not been yet broadened to cover hybrid models. This paper proposes a new research model to investigate the understandability of hybrid model representations using a variety of psycho-physiological measurements including eye tracking and galvanic skin response (GSR) together with verbal data analysis. The aim of this research is to ensure a smooth integrationof hybrid modelling technologies in public administrations by investigating the way end-users (i.e., case workers) rely on the different parts of the hybrid process model representation in DCR Graphs, i.e., the graph, the textual annotations describing the law, and the simulation tools to interpret the process model