## 2 Theoretical Considerations  
### Specialists and Generalists  
The concept of _issue publics_ provides theoretical reasons to believe that citizens tend to be specialists than generalists. [PERSON] [10] invoked the issue publics to offer a realistic explanation of how citizens can respond to public policy in a rational manner, despite their low level of general political interest and knowledge. For most people, once having managed their more pressing matters of family, job, and leisure, they have few resources and little energy left to study every social and political issue. As the cost of becoming well informed in general is substantial, people are expected to focus on only a handful of issues at best. Thus, the theory of issue publics suggests that citizens tend to be specialists, who are experts in a particular domain though lacking interests in other domains.  
However, empirical research has not met theoretical expectations. The evidence has been mixed. [PERSON] [4] found that educated individuals are more familiar with political issues and more knowledgeable about political events in general. [PERSON] and [PERSON] [3] were also skeptical about the existence of a multitude of distinct specialists, showing that knowledge about the United Nations was a good predictor of knowledge about racial issues. These researchers concluded that, if citizens are informed about a certain topic, they tend to be informed about other issues as well. Such studies suggested that some general characteristics of individuals (e.g., education) are significant predictors of interest or knowledge across issues--a view that rests on the assumption that the more educated are presumably equipped with greater sophisticated cognitive ability that enables them to organize abstract ideas to understand complex political matters [11].  
Yet, several studies [1, 12, 13, 14] have reported that people are interested in only a few issues and attach varying degrees of attitude importance to each issue. Analyzing the American National Election Study (ANES) data, [PERSON] [1] found no strong correlations among the perceived importance of various issues. For example, respondents perceiving foreign policy to be important were not necessarily to think that domestic social issues were also important.  
Although both sides have gained empirical support in their own right and attracted some scholarly attention, the literature has not fully flourished yet. In particular, since [PERSON] and [PERSON] [3] did not find much indication of information specialists in their extensive project, research has not been fully flourished in this area. One reason is that much research has framed the question at the aggregate level and examined whether specialists or generalist prevail in the society. In contrast, little is known about who are likely to become specialists and what characteristics each type of citizen has. The individual-level approach that examines various factors contributing to a specialist or generalist will generate empirical evidence that has been lacking in this debate. Henceforth, this study puts forth to refine a measure for the individual tendency to be specialists or generalists and examines the characteristics of specialists and generalists.