A key challenge in COVID-19 public health messaging is that recommendations are often ambiguous. This is because public health appeals are often necessarily nuanced and cannot provide detailed instructions about appropriate behaviour in all possible circumstances. Further, conflicting advice from overlapping jurisdictions – federal, provincial, municipal – may increase ambiguity. This leaves individuals to infer appropriate behaviour in many day-to-day circumstances. When people confront ambiguity in expert recommendations, they may resolve uncertainty by ignoring recommendations they dislike. This is because individuals engage in “motivated reasoning”. On one hand, people do not wish to be wrong, and so accept information they believe will lead to accurate inferences. At the same time, when information is inconvenient—e.g. by being inconsistent with preferred behaviours—people are more likely to accept information consistent with those preferences and reject/ignore inconsistent information. Ambiguity creates “wiggle room”, allowing people to interpret government recommendations in ways consistent with their underlying preferences. People eager to resume normal life may use motivated reasoning to interpret messaging to infer that certain behaviours are appropriate when they are not. We test the hypothesis that ambiguous public health recommendations will result in motivated reasoning by those with priors that are inconsistent with the recommendations through an online survey experiment.