Messaging migration: media agenda-setting, immigration attitudes, and the effects of evidence on perceptions and policy preferences

How do messages impact what people think? Although this broad question speaks to current debates about the role of information in politics, variations of it have appeared throughout political science. My approach draws upon political communication, psychology, and linguistics to demonstrate how information relates to attitudes, perceptions, and policy preferences. Across four separate studies that use the issue of immigration in the British case, I address several sub-questions. First, how has the British press—itself a key messenger of political information—portrayed immigration and immigrants over several decades? Applying corpus linguistic methods, I find press coverage about immigration has both increased and been characterised by several sub-agendas. Second, how have these messages at the word-level related to changes in public concern about immigration? Using time series models, I show how specific dimensions of immigration—its sociocultural, geographic, and numerical aspects—and not overall levels of coverage are related to aggregate public concern. These two studies collectively demonstrate how the agenda-setting power of print media is likely more subtle and delimited than commonly expected. In the third study, I focus on the individual-level impacts of messages. Which qualities of immigrants matter more for public attitudes? Findings from a nationally-representative conjoint survey experiment demonstrate how the British public places greater importance on skill level and language fluency when evaluating individual immigrants. Finally, I broaden my view of messages to include different types of supporting evidence. Do arguments citing numerical or narrative evidence impact public perceptions and policy preferences? A second nationally-representative survey experiment shows how positive messages about immigrants featuring numerical or narrative supporting evidence can positively change perceptions, especially among people who would be expected to hold more negative views. But, the presence of extra information neither raises perceptions more than similarly positive messages lacking evidence, nor influences policy preferences.