Abstract
This paper examines the effects of our modern media environment on affective polarization. We conducted an experiment during the last month of the 2012 presidential election varying both the choice of media sources available about the major presidential candidates, and the tone of political advertisements presented to subjects. We posit that voters in a high-choice, ideologically-diverse media environment will exhibit greater affective polarization than those in a “mainstream” ideologically neutral environment. We also hypothesize that subjects who are exposed to negative rather than positive political advertisements will show increased affective polarization. We provide causal evidence that the combination of a high-choice ideologically diverse media environment and exposure to negative political ads, significantly increases affective polarization. We also find that both overall information search and selective exposure to information are influenced by our experimental manipulations, with the greatest amount of search, and the most biased search, conducted by Romney supporters in the Negative Ads, Diverse Media condition.
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Notes
Although the remote control was invented in 1955, it was considered an expensive luxury device for several more decades. In 1979 only 17 % of US households with televisions had a remote control (Benson-Allott 2014). To switch to another program, most people had to get up off the couch, walk over to the television set, and manually change channels. Although we have no direct evidence on this point, we feel safe in asserting that people were much less likely to change channels in the Broadcast News era than they are today.
The experimental evidence for selective exposure is, in fact, quite mixed (Sears and Freedman 1967), but the theory is clear. There are, of course, other motivations besides dissonance avoidance that can guide information search, and would push viewers in the opposite direction. For example, Valentino et al. (2009) and Pierce (2014) provide evidence that partisans who believe they will have to justify their candidate preference seek out information from the less preferred candidate so that they will be better prepared to counter-argue it.
Readers who would like to see the experiment can go to http://dpte.polisci.uiowa.edu/dpte/action/player/launch/471?test=1&pass=Election2012 Click on the "submit" button, and then click on "Launch Player."
We attempted to contact all subjects again after the election to record their actual vote choice. The very brief post-election portion of the study only asked subjects if they had voted, and if so which candidate they had supported. We obtained post-election data from 256 or 52 % of the people who completed the pre-election portion of the study. As we do not examine those data in this paper, however, we make no further mention of them.
Eleven people began the study but quit before they completed it, and we could not use their data. Ten other people missed one of the two “trap” questions that were included to make sure subjects were paying attention, and we eliminated their data as well. Inclusion of these latter subjects does not substantively alter the results reported herein. See Kleinberg et al (2014) for a more thorough discussion of using MTurk subjects in fairly complex, time-consuming experiments.
The unweighted data were 81 % white, and 58 % pre-election preference for Obama.
Our experiment does not include a pure control group where subjects are exposed to no manipulations and only respond to the dependent variable questions. See the appendix for a discussion of this design decision.
We randomly manipulated whether Obama’s ad or Romney’s ad was shown first, which is treated as a nuisance factor and ignored in the subsequent analysis.
Selecting which ads to use, out of the dozens of positive and negative ads produced by the campaigns, created many challenges. We selected these ads based upon their (1) appeal to a national rather than local or regional audience, (2) alignment with the campaigns’ current message focuses (as of mid-September 2012), and (3) relatively low TV exposure (as best we could determine at the time). This, we hope, exposed our subjects to messages that they might plausibly encounter during the point of the campaign they viewed them, but that they were unlikely to have actually seen yet. This created an imbalance in the ads (they spoke about different issues), at the expense of strengthening the external validity of the study by making the ads seem more appropriate to the current tenor of the campaigns. We assume that the campaigns had good reasons for creating these ads and, rather than attempt to match the ads (i.e. have them speak to the same issue), we allowed the campaigns themselves to influence the ads we included, allowing us to observe what effects these real ads created in the public.
The topics included the economic stimulus, government spending, health insurance, taxes, abortion, education policy, gay rights, gun control, women’s rights, defense spending, the environment, immigration, military interaction, terrorism, political philosophy, the candidate’s family, personality, and personal wealth. There were also articles on recent poll results from the election.
In Appendix Figure A6, articles about Obama are on the left, articles about Romney on the right. “Side” (that is, which candidate was listed first) was another random manipulation that we again treat as a nuisance factor and ignore in the analysis.
As a manipulation check, we conducted a preliminary study in which all articles were rated on a scale of ideological extremity. As we hoped, the articles available from the two liberal media outlets (mean rating 2.5) were indeed judged to have a significant pro-Obama/Democratic/liberal bias compared to articles from the four mainstream sources (mean of 2.9), while the articles selected from the two conservative sources (mean of 3.6) were judged to have a greater pro-Romney/Republican/conservative bias compared to the mainstream articles. More details about this study are provided in the Online Appendix.
To learn more about this program, which is freely available to researchers, go to www.processtracing.org.
Our rationale for excluding these cases is methodological, to ensure that we are looking at subjects who are participating in the study and acting within the bounds of normal behavior. Subjects were required to view 7 items before they could complete the information search process, but could get around this restriction by, for example, viewing the same article multiple times. We determined that subjects who viewed any item more than twice were most likely not seeking to truly learn information and but were instead simply speeding through the study rather than truly participating. Looking at the time subjects spent viewing items a second time, which is minimal, also supports this decision. Likewise, we exclude a few subjects who viewed several standard deviations more items than everyone else as outliers who were not behaving within the bounds of “normal” subject behavior.
We ran this same analysis on a dependent variable measuring “depth of processing,” calculated as the amount of time spent reading a particular information item, controlling for the total number of words in that item, and individual reading speeds. Results were somewhat weaker statistically but essentially replicate the findings for Discretionary Information Search. See Tables A5 and Figure A10 in the online appendix for more information about this analysis.
At the end of the experiment subjects were asked how much they “thought they had learned” about Barack Obama and Mitt Romney from the experiment. We combined these two items into a summary scale of Perceived Candidate Learning and analyzed it as a function of our experimental manipulations. The details of this analysis are reserved for Table A6 and Figure A11 in the online appendix. There is a strong main effect of Media Environment on Perceived Learning, but as can be seen in Figure A11, subjects thought they learned much more in the two treatment conditions where they could read articles, compared to the control condition where they only viewed two political ads. There was virtually no difference between the Mainstream and Ideological media environments on perceived learning, nor was there any effect of Ad Tone. Thus the results for Perceived Learning do not mirror those for Information Search, suggesting that that search was motivated more by directional than accuracy concerns, indirectly reinforcing our findings on Selective Exposure.
One of the anonymous reviewers of this paper suggested that our Affective Polarization results might be conditioned by Strength of Party ID, which by itself has often been found to be a strong predictor of polarization. Strength of Party ID does not interact with any of our experimental manipulations in Table 4, where the dependent variable of strength of vote choice preference; but it comes close (p < .06) in the analysis of feeling thermometer Affective Polarization reported in Table 3. The stronger Affective Polarization results seen in the Ideological Media Environment Negative Ads condition are especially exaggerated among strong partisans (compared to independents). The details of the analysis are presented in Tables A7 and A8 in the online appendix.
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Lau, R.R., Andersen, D.J., Ditonto, T.M. et al. Effect of Media Environment Diversity and Advertising Tone on Information Search, Selective Exposure, and Affective Polarization. Polit Behav 39, 231–255 (2017). https://doi.org/10.1007/s11109-016-9354-8
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DOI: https://doi.org/10.1007/s11109-016-9354-8
Keywords
- Affective polarization
- Information search
- Negative advertising
- Partisan media environment
- Political polarization
- Selective exposure