Emotions influence attitude formation and behaviour of agents. Reliably measuring emotions in experimental research is difficult, however, since self-reported measures are subject to a number of crucial limitations. In this pre-analysis plan, I outline how I will use facial emotion recognition software to unobtrusively measure the emotional reactions of participants. Using videos that elicit strong emotional reactions as treatments, I will explore if and how facial emotion recognition can be harnessed in social science research, particularly surrounding our understanding of the psychology of voters.