Mainstream media and electoral outcomes


Latest electoral outcomes such because the election of Donald Trump in 2016 or the Brexit vote that very same yr shocked many people. Many seen these outcomes as ‘flawed’ within the sense that data was not aggregated accurately. Particularly, factually incorrect beliefs about many elements of those elections continued and decided these mixture decisions. A suspect perpetrator for the misinformation that led to such decisions has been the brand new media, typically accused of being biased and partisan, a debate that’s ongoing. 

The media panorama has modified drastically over the previous a number of years. Mainstream cable information was the dominant information supplier, however within the present setting, folks can select to eat information from a plethora of doable media sources – starting from print media to YouTube channels. The richness of recent media has maybe benefited folks by permitting them to tailor their media decisions to their needs. Nevertheless, the unbelievable range of viewpoints on supply, mixed with new applied sciences, has made it simpler for residents to change into insulated from presumably opposite views supplied, as an example, by conventional media shops. A number of papers have seemed on the results of echo chambers and the electoral penalties of unawareness of being in echo chambers (e.g. Levy and Razin 2015, Ortoleva and Snowberg 2015). 

Metejka and Tabellini (2020, 2021) additionally present that the number of media sources obtainable permits folks to divert consideration away from vital however non-controversial points in direction of extra excessive coverage dimensions, thus amplifying their affect. 

Whereas the media panorama has change into a lot richer, belief in conventional media has declined markedly over the previous twenty years. Particularly up to now 5 years, this media mistrust has adopted radically completely different paths on both aspect of the political spectrum within the US. As we will see beneath, the hole in media belief between Republicans and Democrats is staggering and widened in the course of the Trump presidency – presumably because of the former president’s well-documented disparaging of the mainstream media. 

Determine 1 Asymmetry in belief in mass media

Certainly, as famous by the Pew Basis in Jurkowitz et al. (2020), “one of many clearest variations between People on opposing sides the political aisle is that enormous parts of Democrats specific belief in a far larger variety of information sources.” 

The affect of the above-mentioned phenomena on mixture electoral outcomes is compounded, particularly within the US, by the presence of a really polarised panorama wherein conventional ideological, non secular, and racial identities are being changed by overlapping meta-identities captured nearly solely by the Democratic and Republican political faiths. Residents have change into much less attentive to new data or actual nationwide issues, as if political affiliations decide what data folks take up, quite than the opposite manner round (e.g. Mason 2018). Moreover, Kahan (2017) finds that individuals exhibit motivated reasoning to guard political identification, whereas Kaanders et al. (2022) notice that people seek for data to protect their beliefs. 

Relatedly, Guriev et al. (2019, 2021) present how the web has led to elevated help for each left-wing and right-wing populist actions by lowering the price of reaching voters.

These three phenomena — the emergence of a dense array of media shops, partisan mistrust of media, and motivated selection of media by residents — have repercussions for the way political views are fashioned and up to date, and thus for folks’s choices on election day. However can this new data setting generate mixture beliefs biased sufficient to swing an election? Additional, can it present a rationale behind the fomenting of mistrust in mainstream media noticed in the course of the Trump presidency?

Id-based preferences

Taking heed of the above points, our current paper (Herrera and Sethi 2022) explores the hyperlink between political identities, media decisions, and electoral outcomes. 

We assume that every citizen identifies with a celebration, on the left or the fitting, and goals to guard their political identification. They select media to maximise the probability that after their beliefs are rationally up to date, they consider their get together is the higher match for the state of the world. Such beliefs are primarily based on simply two alerts: an ‘Inside’ sign and an ‘Outdoors’ sign. The Inside sign is generated from a construction that represents the gathering of media shops an agent chooses. The Outdoors sign comes from shops an agent is inadvertently uncovered to – the character of this sign will rely on the character of mainstream media at giant. In different phrases, residents select media making an attempt to defend themselves from presumably unfavourable (from the standpoint of their political affiliation) outdoors information to which they’re considerably uncovered. 

Equivalently, one can consider brokers as having two selves – a coronary heart and a thoughts. The guts chooses Inside media whereas the thoughts votes sincerely. The target of the center is to steer the thoughts to vote for the center’s most popular get together. In both interpretation, residents are totally rational in the best way they course of all data they obtain and replace their beliefs primarily based on the 2 alerts and vote in response to their posterior for the higher candidate. 

The election aggregates all votes, every primarily based on two conditionally unbiased alerts of which of two candidates is preferable. The important thing behavioural assumption of our mannequin regards not data processing however the choice that drives every citizen’s selection of ‘In-media’, i.e. the tailor-made media shops, every of which we view as a selected recognized sign construction.

Asymmetry in publicity to outdoors information

Residents that mistrust the mainstream media might select to keep away from publicity to it. Thus, an uneven mistrust of mainstream media might indicate an asymmetry in publicity. The character of media that brokers select to eat (‘In-media’) is influenced by their beliefs concerning the mainstream (‘Outdoors’) media. A distinction in media selection has stunning implications for electoral outcomes. 

Within the instance beneath, we research the dimensions of the electoral benefit (successful margin) of the aspect much less uncovered to mainstream media assuming that every citizen votes for the get together she rationally beliefs to be superior. We assume that residents of both sort (left- or right- affiliated) are symmetric in all respects aside from publicity. Particularly, there’s a giant and equal variety of partisans of every sort, ‘L’ and ‘R’. Additionally, there are two equally doubtless states of the world, ω = L, R, denoting which of two candidates is the higher one.

To focus on the implications of wealthy media panorama made doable by the proliferation of recent media, we first think about electoral outcomes within the absence of Inside media and examine that with outcomes wherein residents select their Inside media. 

We conceptualise uneven publicity by supposing that type-L residents obtain i.i.d. symmetric binary alerts from mainstream information with precision 0.75, whereas type-R residents obtain noisier i.i.d. mainstream alerts, specifically with a decrease precision of 0.51. The successful margin and successful likelihood for the R aspect rely solely on the realisations of the Outdoors sign and are summarised within the desk beneath:

Thus, uneven publicity to mainstream media generates symmetric electoral outcomes. On this baseline case, the perfect/appropriate candidate is all the time elected, i.e. data is completely aggregated. No private media selection is made by residents, and thus political religion, or the kind of citizen, performs no position.

Now, suppose as a substitute that residents may curate Inside media sources optimally. Right here, their voting resolution is made after updating rationally on two alerts, not one. If every agent chooses media to maximise the possibility of political religion preservation, then the end result of the election is not symmetric. The truth is, it could be drastically skewed. On this instance, the successful margin and successful likelihood for the R aspect are:

On this case, the R aspect has an ex-ante successful margin benefit within the election. Surprisingly, it additionally has a bonus ex-post. Specifically, the R aspect wins the election in both state of the world on this case and knowledge shouldn’t be aggregated, regardless of brokers voting primarily based solely on (rational updating of) the data they acquired.


The stunning outcome above is pushed by the truth that residents on both political aspect select qualitatively completely different media. Much less-exposed residents (the fitting in our instance) cope with a far much less informative Outdoors sign, which means that they maximise the probability of preserving their political religion by selecting a one-sided sign construction, for which information beneficial to 1 candidate may be very frequent and thus not so informative, whereas unfavourable information is uncommon and therefore damning. That is maybe harking back to partisan shops like Fox Information or Breitbart Information for Republicans. Then again, to cope with the extra informative Outdoors sign, more-exposed residents (the left in our instance) optimally select extra balanced information.

Importantly, in a world with no wealthy set of sign constructions (In-media) obtainable to brokers to pick from, even when partisan biases that drive media selection have been current, we’d not see the stark bias in mixture electoral outcomes within the instance above.

Moreover, we discover that an asymmetry in mistrust of the mainstream media by partisan residents can result in a considerable electoral benefit for the much less trusting aspect. The mechanism that generates this benefit stays that distrusting residents largely disregard an unfavourable Outdoors sign, which induces them to decide on extra biased Inside media, which preserves their political religion with a larger probability even within the incorrect state of the world. This can be one cause we have now noticed get together elites disparage the mainstream media.

If residents on the 2 sides even have heterogeneous priors biased in direction of their aspect, then the scope for the failure of knowledge aggregation expands. Outcomes are qualitatively unchanged if we assume that every citizen votes for her culturally affiliated get together provided that she believes it’s higher, and abstains in any other case, specifically if we assume turnout/abstention margins decide electoral outcomes. On this case, all successful margins would merely be halved. The outcomes are additionally strong to brokers putting utility on holding posteriors extra beneficial to their aspect, or a small quantity of utility on voting for the right get together.


Benkler, Y, R Faris, H Roberts and E Zuckerman (2017), “Examine: Breitbart-led right-wing media ecosystem altered broader media agenda”, Columbia Journalism Overview. 

DellaVigna, S and E Kaplan (2007), “The Fox Information impact: Media bias and voting”, Quarterly Journal of Economics 122(3): 1187–1234.

Guriev, S, N Melnikov and E Zhuravskaya (2019), “Information is energy: Cellular web, authorities confidence, and populism”,, 31 October. 

Guriev, S, N Melnikov and E Zhuravskaya (2021), “3g web and confidence in authorities”, Quarterly Journal of Economics 136(4): 2533-2613.

Herrera, H and R Sethi (2022), “Id-Primarily based Elections”, CEPR Dialogue Paper 17203.

Jurkowitz, M, A Mitchell, E Shearer and M Walker (2020), “U.S. media polarization and the 2020 election: A nation divided”, Pew Analysis Middle. 

Kaanders, P, P Sepulveda, T Folke, P Ortoleva and B De Martino (2022), “People actively pattern proof to help prior beliefs”, Elife 11: e71768.

Kahan, Dan M (2017), “Misconceptions, Misinformation, and the Logic of Id-Protecting Cognition”, Yale Legislation & Economics Analysis Paper No. 575. 

Levy, G and R Razin (2015), “Correlation neglect, voting conduct, and knowledge aggregation”, American Financial Overview 105(4): 1634–45. 

Mason, L (2018), Uncivil settlement: How politics turned our identification, College of Chicago Press.

Matějka, F and G Tabellini (2020), “Political data within the age of the web”,, 10 January. 

Matějka, F and G Tabellini (2021), “Electoral competitors with rationally inattentive voters”, Journal of the European Financial Affiliation 19(3): 1899-1935. 

Ortoleva, P and E Snowberg (2015), “Overconfidence in political conduct”, American Financial Overview 105(2): 504–35.



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