In early research, selective exposure originally provided an explanation for limited media effects. The "limited effects" model of communication emerged in the 1940s with a shift in the media effects paradigm. This shift suggested that while the media has effects on consumers' behavior such as their voting behavior, these effects are limited and influenced indirectly by interpersonal discussions and the influence of opinion leaders. Selective exposure was considered one necessary function in the early studies of media's limited power over citizens' attitudes and behaviors. Political ads deal with selective exposure as well because people are more likely to favor a politician that agrees with their own beliefs. Another significant effect of selective exposure comes from Stroud (2010) who analyzed the relationship between partisan selective exposure and political polarization. Using data from the 2004 National Annenberg Election Survey, analysts found that over time partisan selective exposure leads to polarization. This process is plausible because people can easily create or have access to blogs, websites, chats, and online forums where those with similar views and political ideologies can congregate. Much of the research has also shown that political interaction online tends to be polarized. Further evidence for this polarization in the political blogosphere can be found in the Lawrence et al. (2010)'s study on blog readership that people tend to read blogs that reinforce rather than challenge their political beliefs. According to Cass Sunstein's book, "Republic.com", the presence of selective exposure on the web creates an environment that breeds political polarization and extremism. Due to easy access to social media and other online resources, people are "likely to hold even stronger views than the ones they started with, and when these views are problematic, they are likely to manifest increasing hatred toward those espousing contrary beliefs." This illustrates how selective exposure can influence an individual's political beliefs and subsequently his participation in the political system.