October Surprises: Threshold Dynamics in Belief Formation Modeling

October Surprises, or political catastrophes in the final weeks of the U.S. presidential elections, can profoundly alter the dynamics of a campaign. In an increasingly politically polarized society, understanding the conditions that lead voters to believe or reject October Surprises is of great importance to election results. This study details the results of an agent-based model simulating how agents’ beliefs about an October Surprise are shaped by ideological alignment and social pressure, the two model parameters. The model was found to produce clear threshold dynamics in both parameters, with ideological alignment having the stronger threshold. Real-world implications for campaign strategy are discussed.