Stay positive or go negative? Memory imperfections and messaging strategy

This paper studies the optimal mix of message content in elections while explicitly accounting for voters' memory imperfections. We build an analytical model of a political contest between two candidates facing an election with an electorate consisting of supporters, opponents, and undecided voters. The candidates take decisions on advertising sequence and content (positive vs. negative). Our model explicitly considers the role of memory processes, in particular decay (the idea that memories fade with time) and rehearsal (the idea that accessing a memory eases its recall,) that crucially affect how effective ads are in influencing choice. The model yields several interesting insights: (a) when both candidates have low initial support, they invest only in positive messages; (b) when both candidates are endowed with high initial support, their messaging strategies take a “pulsing” shape involving negative advertising accompanied by positive advertising; (c) when one candidate has low initial support while the other has high initial support, the former adopts a “pulsing” strategy while the latter adopts only positive advertising. Furthermore, we show that a candidate with low initial support facing a candidate with high initial support responds with a messaging strategy bunched with negative content towards the end of the election cycle. Our model's predictions are shown to find empirical support in a dataset assembled from 2016 U.S. Senate races.