Decades of behavior research have shown that political interest is the most important predictor of political knowledge and citizen participation. Political interest and knowledge, in turn, are at the core of democratic citizenship and the quality of representative democracy. An under-appreciated fact about political interest, however, is that typical levels of political interest (and thus political knowledge) vary dramatically across countries. Current theories of political interest and knowledge, however, explain little about why such differences occur and persist. This dissertation attempts to fill that void by proposing a novel theoretical framework for why individuals do or do not become interested in politics. This new theory leads directly to hypotheses about how typical levels of political interest can vary across different political contexts.

The individual level theory draws on appraisal models of interest in psychology. These models show that appraising an event or a message as "comprehensible" (or, more generally, as being able to cope with it) is one of several necessary conditions for individuals to be interested in the event or message (e.g., Silvia 2006). Drawing on a large body of work in political psychology which highlights the critical role heuristics play in helping individuals comprehend politics, I extend the appraisal model of interest to include a role for heuristics in enhancing comprehensibility and therefore interest. Adding heuristics to the appraisal model of interest is the key to understanding cross-national variation in typical levels of political interest. Specifically, I argue that a specific set of simplifying heuristics that work to make politics more "comprehensible" is the main driver of the temporal and cross-national differences in political interest.

The micro-foundations of the argument are examined by implementing a unique experimental design that manipulates the availability of heuristics for different groups. The experimental results support the proposed mechanism, demonstrating that individuals in contexts where heuristics are available and useful are more interested in experimental tasks. To validate the main argument for the cross-national differences in political interest, I introduce a set of measurements tapping into the political contexts associated with the availability and usefulness of common political heuristics, and test the argument using a comprehensive dataset combining a large pool of cross-national surveys and various contextual measures.