Bias and Credibility: Explaining Partisan News Choice

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Principal investigator:

Dimitri Kelly

University of Wisconsin-Madison



Sample size: 731

Field period: 10/3/2011-1/11/2012


Evidence points to partisan segmentation in the contemporary news market, but the mechanism causing consumers to sort along party lines is unclear. This study develops a framework for news choice based on perceived credibility and reports results from a nationally representative survey experiment identifying the effect of message content on perceptions of news bias and source credibility. I find support for a congenial media effect, where information consistent with existing beliefs is seen as more credible and less biased. I contend that political segregation of news audiences can be best understood as the product of distorted perceptions about news outlets’ political biases, individual’s desire for credible information, and the conflating of credibility with objectivity.


(H1) Congenial Media Effect: News coverage presenting biased information supporting recipients’ positions will be perceived as objective.

(H2) Credible Media Effect: News coverage presenting biased information supporting recipients’ positions will be perceived as more credible than either more balanced or actively hostile coverage.

(H3) Party Identification: Both congenial and credible media responses will be greater for Republicans than for Democrats.

(H4) Party Strength: Both congenial and credible media responses will be greater among those heavily invested in politics than among those not heavily invested.

(H5) News Junkies: Both congenial and credible media responses will be greater among heavy news consumers than among less active news consumers.

Experimental Manipulations

Respondents were randomly presented with one of three transcripts compiled from actual news reports and interviews, each providing a competing political perspectives on the two-year extension of the Bush tax-cuts recently voted on by Congress (pro-Democratic, pro-Republican and balanced).


BIAS is measured using a post-treatment ordinal scale (0-5) of the degree of bias the respondent perceived in the news program, where zero is unbiased and five is very biased.

CREDIBILITY is measured using a post-treatment additive index created from three questions about the news coverage: how much individual i believes the information presented in the program, how much individual i believes information from, and how informative individual i found the program to be.

Summary of Results

This study proposed and finds empirical support for a mechanism of news choice based on the assumption that people desire unbiased and credible political coverage, but where cognitive biases in information processing cloud their perceptions. As a result, individuals see bias where none exists and objectivity in bias flattering to their worldview. At the same time, for those heavily invested in politics, the credibility of news coverage is determined in part by the extent to which it reflects their preferred political worldview. Perversely, the desire for unbiased and credible news may contribute to audiences sorting into biased news sources.

It comes as no surprise that people do not view all news sources as equal. However, because the bulk of recent political selective exposure research has relied either on traditional survey data (e.g. Morris 2007; Stroud 2007; 2008) or used experimental manipulations with source cues (e.g. Iyengar and Hahn 2008; Turner 2007; Arceneaux et al. 2012), until now scholars have been unable say much about the selection process more definitive or empirical than Republicans prefer Fox News because it is conservative and Democrats avoid it for the same reason. By holding source constant and varying content, the experiment presented here solves the problem of endogenous selection, providing new insights into political selective exposure by focusing on the causal mechanisms driving it.

Additional Information

In preparation for submission to an academic journal.


Kelly, Dimitri. 2012. “Unbiased and Credible: Motivating Partisan News Choice.” APSA Annual Meeting Paper. New Orleans.