Governments often need to introduce policies to change public behaviour to address societal challenges such as climate change. Initially, public support for these policies can be low, making it difficult to implement them successfully. A recent review found that communicating evidence about a policy's effectiveness can increase public support by a small but potentially meaningful amount. Our research aims to build on this finding by addressing four limitations of the previous studies included in the review. We will 1. Assess how different types of evidence (statistics, anecdotes, or a combination of both) affect people's beliefs about a policy's effectiveness and their support for the policy. This is important because in real-world contexts, people often encounter multiple, sometimes conflicting, pieces of evidence, whereas previous studies typically present evidence about a policy's effectiveness in isolation. 2. Investigate how people evaluate the evidence they encounter and how this influences their beliefs about a policy's effectiveness. Understanding this cognitive process could help determine why different types of evidence are more or less effective for policy communication. Previous studies do not typically assess evidence evaluation despite it being an important process that affects how people update their beliefs in response to new evidence. 3. Examine how the effects of evidence type on policy beliefs, policy support, and evidence evaluation vary across people. This could help identify which groups are most and least receptive to different types of evidence and why. Previous studies often overlook that people can respond differently to the same evidence, focusing instead on average effects across the sample. 4. Explore how people's broader belief systems, such as their views on who is responsible for addressing societal issues, influence their receptiveness to evidence about policy effectiveness. Previous studies have typically only assessed people's beliefs about a policy's effectiveness without considering the wider context of their beliefs. Results will (i) provide insights that could help policymakers communicate more effectively, and (ii) contribute to theoretical understanding about how people update their beliefs in response to new evidence.