Academic Research

CSMaP faculty, postdoctoral fellows, and students publish rigorous, peer-reviewed research in top academic journals and post working papers sharing ongoing work.

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  • Journal Article

    Estimating the Ideology of Political YouTube Videos

    Political Analysis, 2024

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    We present a method for estimating the ideology of political YouTube videos. As online media increasingly influences how people engage with politics, so does the importance of quantifying the ideology of such media for research. The subfield of estimating ideology as a latent variable has often focused on traditional actors such as legislators, while more recent work has used social media data to estimate the ideology of ordinary users, political elites, and media sources. We build on this work by developing a method to estimate the ideologies of YouTube videos, an important subset of media, based on their accompanying text metadata. First, we take Reddit posts linking to YouTube videos and use correspondence analysis to place those videos in an ideological space. We then train a text-based model with those estimated ideologies as training labels, enabling us to estimate the ideologies of videos not posted on Reddit. These predicted ideologies are then validated against human labels. Finally, we demonstrate the utility of this method by applying it to the watch histories of survey respondents with self-identified ideologies to evaluate the prevalence of echo chambers on YouTube. Our approach gives video-level scores based only on supplied text metadata, is scalable, and can be easily adjusted to account for changes in the ideological climate. This method could also be generalized to estimate the ideology of other items referenced or posted on Reddit.

    Date Posted

    Feb 13, 2024

  • Journal Article

    Online Searches to Evaluate Misinformation Can Increase its Perceived Veracity

    Nature, 2024

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    Considerable scholarly attention has been paid to understanding belief in online misinformation, with a particular focus on social networks. However, the dominant role of search engines in the information environment remains underexplored, even though the use of online search to evaluate the veracity of information is a central component of media literacy interventions. Although conventional wisdom suggests that searching online when evaluating misinformation would reduce belief in it, there is little empirical evidence to evaluate this claim. Here, across five experiments, we present consistent evidence that online search to evaluate the truthfulness of false news articles actually increases the probability of believing them. To shed light on this relationship, we combine survey data with digital trace data collected using a custom browser extension. We find that the search effect is concentrated among individuals for whom search engines return lower-quality information. Our results indicate that those who search online to evaluate misinformation risk falling into data voids, or informational spaces in which there is corroborating evidence from low-quality sources. We also find consistent evidence that searching online to evaluate news increases belief in true news from low-quality sources, but inconsistent evidence that it increases belief in true news from mainstream sources. Our findings highlight the need for media literacy programmes to ground their recommendations in empirically tested strategies and for search engines to invest in solutions to the challenges identified here.

    Date Posted

    Dec 20, 2023

  • Journal Article

    A Synthesis of Evidence for Policy from Behavioural Science During COVID-19

    • Kai Ruggeri, 
    • Friederike Stock, 
    • S. Alexander Haslam, 
    • Valerio Capraro, 
    • Paulo Boggio, 
    • Naomi Ellemers, 
    • Aleksandra Cichocka, 
    • Karen M. Douglas, 
    • David G. Rand, 
    • Sander van der Linden, 
    • Mina Cikara, 
    • Eli J. Finkel, 
    • James N. Druckman, 
    • Michael J. A. Wohl, 
    • Richard E. Petty, 
    • Joshua A. Tucker
    • Azim Shariff, 
    • Michele Gelfand, 
    • Dominic Packer, 
    • Jolanda Jetten, 
    • Paul A. M. Van Lange, 
    • Gordon Pennycook, 
    • Ellen Peters, 
    • Katherine Baicker, 
    • Alia Crum, 
    • Kim A. Weeden, 
    • Lucy Napper, 
    • Nassim Tabri, 
    • Jamil Zaki, 
    • Linda Skitka, 
    • Shinobu Kitayama, 
    • Dean Mobbs, 
    • Cass R. Sunstein, 
    • Sarah Ashcroft-Jones, 
    • Anna Louise Todsen, 
    • Ali Hajian, 
    • Sanne Verra, 
    • Vanessa Buehler, 
    • Maja Friedemann, 
    • Marlene Hecht, 
    • Rayyan S. Mobarak, 
    • Ralitsa Karakasheva, 
    • Markus R. Tünte, 
    • Siu Kit Yeung, 
    • R. Shayna Rosenbaum, 
    • Žan Lep, 
    • Yuki Yamada, 
    • Sa-kiera Tiarra Jolynn Hudson, 
    • Lucía Macchia, 
    • Irina Soboleva, 
    • Eugen Dimant, 
    • Sandra J. Geiger, 
    • Hannes Jarke, 
    • Tobias Wingen, 
    • Jana Berkessel, 
    • Silvana Mareva, 
    • Lucy McGill, 
    • Francesca Papa, 
    • Bojana Većkalov, 
    • Zeina Afif, 
    • Eike K. Buabang, 
    • Marna Landman, 
    • Felice Tavera, 
    • Jack L. Andrews, 
    • Aslı Bursalıoğlu, 
    • Zorana Zupan, 
    • Lisa Wagner, 
    • Joaquin Navajas, 
    • Marek Vranka, 
    • David Kasdan, 
    • Patricia Chen, 
    • Kathleen R. Hudson, 
    • Lindsay M. Novak, 
    • Paul Teas, 
    • Nikolay R. Rachev, 
    • Matteo M. Galizzi, 
    • Katherine L. Milkman, 
    • Marija Petrović, 
    • Jay J. Van Bavel
    • Robb Willer

    Nature, 2023

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    Scientific evidence regularly guides policy decisions, with behavioural science increasingly part of this process. In April 2020, an influential paper proposed 19 policy recommendations (‘claims’) detailing how evidence from behavioural science could contribute to efforts to reduce impacts and end the COVID-19 pandemic. Here we assess 747 pandemic-related research articles that empirically investigated those claims. We report the scale of evidence and whether evidence supports them to indicate applicability for policymaking. Two independent teams, involving 72 reviewers, found evidence for 18 of 19 claims, with both teams finding evidence supporting 16 (89%) of those 18 claims. The strongest evidence supported claims that anticipated culture, polarization and misinformation would be associated with policy effectiveness. Claims suggesting trusted leaders and positive social norms increased adherence to behavioural interventions also had strong empirical support, as did appealing to social consensus or bipartisan agreement. Targeted language in messaging yielded mixed effects and there were no effects for highlighting individual benefits or protecting others. No available evidence existed to assess any distinct differences in effects between using the terms ‘physical distancing’ and ‘social distancing’. Analysis of 463 papers containing data showed generally large samples; 418 involved human participants with a mean of 16,848 (median of 1,699). That statistical power underscored improved suitability of behavioural science research for informing policy decisions. Furthermore, by implementing a standardized approach to evidence selection and synthesis, we amplify broader implications for advancing scientific evidence in policy formulation and prioritization.

    Date Posted

    Dec 13, 2023

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  • Journal Article

    Testing the Effect of Information on Discerning the Veracity of News in Real Time

    Journal of Experimental Political Science, 2023

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    Despite broad adoption of digital media literacy interventions that provide online users with more information when consuming news, relatively little is known about the effect of this additional information on the discernment of news veracity in real time. Gaining a comprehensive understanding of how information impacts discernment of news veracity has been hindered by challenges of external and ecological validity. Using a series of pre-registered experiments, we measure this effect in real time. Access to the full article relative to solely the headline/lede and access to source information improves an individual's ability to correctly discern the veracity of news. We also find that encouraging individuals to search online increases belief in both false/misleading and true news. Taken together, we provide a generalizable method for measuring the effect of information on news discernment, as well as crucial evidence for practitioners developing strategies for improving the public's digital media literacy.

    Date Posted

    Nov 08, 2023

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  • Journal Article

    Replicating the Effects of Facebook Deactivation in an Ethnically Polarized Setting

    Research & Politics, 2023

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    The question of how social media usage impacts societal polarization continues to generate great interest among both the research community and broader public. Nevertheless, there are still very few rigorous empirical studies of the causal impact of social media usage on polarization. To explore this question, we replicate the only published study to date that tests the effects of social media cessation on interethnic attitudes (Asimovic et al., 2021). In a study situated in Bosnia and Herzegovina, the authors found that deactivating from Facebook for a week around genocide commemoration in Bosnia and Herzegovina had a negative effect on users’ attitudes toward ethnic outgroups, with the negative effect driven by users with more ethnically homogenous offline networks. Does this finding extend to other settings? In a pre-registered replication study, we implement the same research design in a different ethnically polarized setting: Cyprus. We are not able to replicate the main effect found in Asimovic et al. (2021): in Cyprus, we cannot reject the null hypothesis of no effect. We do, however, find a significant interaction between the heterogeneity of users’ offline networks and the deactivation treatment within our 2021 subsample, consistent with the pattern from Bosnia and Herzegovina. We also find support for recent findings (Allcott et al., 2020; Asimovic et al., 2021) that Facebook deactivation leads to a reduction in anxiety levels and suggestive evidence of a reduction in knowledge of current news, though the latter is again limited to our 2021 subsample.

    Date Posted

    Oct 18, 2023

  • Journal Article

    Like-Minded Sources On Facebook Are Prevalent But Not Polarizing

    • Brendan Nyhan, 
    • Jaime Settle, 
    • Emily Thorson, 
    • Magdalena Wojcieszak
    • Pablo Barberá
    • Annie Y. Chen, 
    • Hunt Alcott, 
    • Taylor Brown, 
    • Adriana Crespo-Tenorio, 
    • Drew Dimmery, 
    • Deen Freelon, 
    • Matthew Gentzkow, 
    • Sandra González-Bailón
    • Andrew M. Guess
    • Edward Kennedy, 
    • Young Mie Kim, 
    • David Lazer, 
    • Neil Malhotra, 
    • Devra Moehler, 
    • Jennifer Pan, 
    • Daniel Robert Thomas, 
    • Rebekah Tromble, 
    • Carlos Velasco Rivera, 
    • Arjun Wilkins, 
    • Beixian Xiong, 
    • Chad Kiewiet De Jong, 
    • Annie Franco, 
    • Winter Mason, 
    • Natalie Jomini Stroud, 
    • Joshua A. Tucker

    Nature, 2023

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    Many critics raise concerns about the prevalence of ‘echo chambers’ on social media and their potential role in increasing political polarization. However, the lack of available data and the challenges of conducting large-scale field experiments have made it difficult to assess the scope of the problem1,2. Here we present data from 2020 for the entire population of active adult Facebook users in the USA showing that content from ‘like-minded’ sources constitutes the majority of what people see on the platform, although political information and news represent only a small fraction of these exposures. To evaluate a potential response to concerns about the effects of echo chambers, we conducted a multi-wave field experiment on Facebook among 23,377 users for whom we reduced exposure to content from like-minded sources during the 2020 US presidential election by about one-third. We found that the intervention increased their exposure to content from cross-cutting sources and decreased exposure to uncivil language, but had no measurable effects on eight preregistered attitudinal measures such as affective polarization, ideological extremity, candidate evaluations and belief in false claims. These precisely estimated results suggest that although exposure to content from like-minded sources on social media is common, reducing its prevalence during the 2020 US presidential election did not correspondingly reduce polarization in beliefs or attitudes.

  • Journal Article

    How Do Social Media Feed Algorithms Affect Attitudes and Behavior in an Election Campaign?

    • Andrew M. Guess
    • Neil Malhotra, 
    • Jennifer Pan, 
    • Pablo Barberá
    • Hunt Alcott, 
    • Taylor Brown, 
    • Adriana Crespo-Tenorio, 
    • Drew Dimmery, 
    • Deen Freelon, 
    • Matthew Gentzkow, 
    • Sandra González-Bailón
    • Edward Kennedy, 
    • Young Mie Kim, 
    • David Lazer, 
    • Devra Moehler, 
    • Brendan Nyhan, 
    • Jaime Settle, 
    • Calos Velasco-Rivera, 
    • Daniel Robert Thomas, 
    • Emily Thorson, 
    • Rebekah Tromble, 
    • Beixian Xiong, 
    • Chad Kiewiet De Jong, 
    • Annie Franco, 
    • Winter Mason, 
    • Natalie Jomini Stroud, 
    • Joshua A. Tucker

    Science, 2023

    View Article View abstract

    We investigated the effects of Facebook’s and Instagram’s feed algorithms during the 2020 US election. We assigned a sample of consenting users to reverse-chronologically-ordered feeds instead of the default algorithms. Moving users out of algorithmic feeds substantially decreased the time they spent on the platforms and their activity. The chronological feed also affected exposure to content: The amount of political and untrustworthy content they saw increased on both platforms, the amount of content classified as uncivil or containing slur words they saw decreased on Facebook, and the amount of content from moderate friends and sources with ideologically mixed audiences they saw increased on Facebook. Despite these substantial changes in users’ on-platform experience, the chronological feed did not significantly alter levels of issue polarization, affective polarization, political knowledge, or other key attitudes during the 3-month study period.

  • Journal Article

    Reshares on Social Media Amplify Political News But Do Not Detectably Affect Beliefs or Opinions

    • Andrew M. Guess
    • Neil Malhotra, 
    • Jennifer Pan, 
    • Pablo Barberá
    • Hunt Alcott, 
    • Taylor Brown, 
    • Adriana Crespo-Tenorio, 
    • Drew Dimmery, 
    • Deen Freelon, 
    • Matthew Gentzkow, 
    • Sandra González-Bailón
    • Edward Kennedy, 
    • Young Mie Kim, 
    • David Lazer, 
    • Devra Moehler, 
    • Brendan Nyhan, 
    • Carlos Velasco Rivera, 
    • Jaime Settle, 
    • Daniel Robert Thomas, 
    • Emily Thorson, 
    • Rebekah Tromble, 
    • Arjun Wilkins, 
    • Magdalena Wojcieszak
    • Beixian Xiong, 
    • Chad Kiewiet De Jong, 
    • Annie Franco, 
    • Winter Mason, 
    • Natalie Jomini Stroud, 
    • Joshua A. Tucker

    Science, 2023

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    We studied the effects of exposure to reshared content on Facebook during the 2020 US election by assigning a random set of consenting, US-based users to feeds that did not contain any reshares over a 3-month period. We find that removing reshared content substantially decreases the amount of political news, including content from untrustworthy sources, to which users are exposed; decreases overall clicks and reactions; and reduces partisan news clicks. Further, we observe that removing reshared content produces clear decreases in news knowledge within the sample, although there is some uncertainty about how this would generalize to all users. Contrary to expectations, the treatment does not significantly affect political polarization or any measure of individual-level political attitudes.

  • Journal Article

    Asymmetric Ideological Segregation In Exposure To Political News on Facebook

    • Sandra González-Bailón
    • David Lazer, 
    • Pablo Barberá
    • Meiqing Zhang, 
    • Hunt Alcott, 
    • Taylor Brown, 
    • Adriana Crespo-Tenorio, 
    • Deen Freelon, 
    • Matthew Gentzkow, 
    • Andrew M. Guess
    • Shanto Iyengar, 
    • Young Mie Kim, 
    • Neil Malhotra, 
    • Devra Moehler, 
    • Brendan Nyhan, 
    • Jennifer Pan, 
    • Caros Velasco Rivera, 
    • Jaime Settle, 
    • Emily Thorson, 
    • Rebekah Tromble, 
    • Arjun Wilkins, 
    • Magdalena Wojcieszak
    • Chad Kiewiet De Jong, 
    • Annie Franco, 
    • Winter Mason, 
    • Joshua A. Tucker
    • Natalie Jomini Stroud

    Science, 2023

    View Article View abstract

    Does Facebook enable ideological segregation in political news consumption? We analyzed exposure to news during the US 2020 election using aggregated data for 208 million US Facebook users. We compared the inventory of all political news that users could have seen in their feeds with the information that they saw (after algorithmic curation) and the information with which they engaged. We show that (i) ideological segregation is high and increases as we shift from potential exposure to actual exposure to engagement; (ii) there is an asymmetry between conservative and liberal audiences, with a substantial corner of the news ecosystem consumed exclusively by conservatives; and (iii) most misinformation, as identified by Meta’s Third-Party Fact-Checking Program, exists within this homogeneously conservative corner, which has no equivalent on the liberal side. Sources favored by conservative audiences were more prevalent on Facebook’s news ecosystem than those favored by liberals.

  • Journal Article

    Measuring the Ideology of Audiences for Web Links and Domains Using Differentially Private Engagement Data

    Proceedings of the International AAAI Conference on Web and Social Media, 2023

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    Area of Study

    Date Posted

    Jun 02, 2023

  • Journal Article

    Exposure to the Russian Internet Research Agency Foreign Influence Campaign on Twitter in the 2016 US Election and Its Relationship to Attitudes and Voting Behavior

    Nature Communications, 2023

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    There is widespread concern that foreign actors are using social media to interfere in elections worldwide. Yet data have been unavailable to investigate links between exposure to foreign influence campaigns and political behavior. Using longitudinal survey data from US respondents linked to their Twitter feeds, we quantify the relationship between exposure to the Russian foreign influence campaign and attitudes and voting behavior in the 2016 US election. We demonstrate, first, that exposure to Russian disinformation accounts was heavily concentrated: only 1% of users accounted for 70% of exposures. Second, exposure was concentrated among users who strongly identified as Republicans. Third, exposure to the Russian influence campaign was eclipsed by content from domestic news media and politicians. Finally, we find no evidence of a meaningful relationship between exposure to the Russian foreign influence campaign and changes in attitudes, polarization, or voting behavior. The results have implications for understanding the limits of election interference campaigns on social media.

    Date Posted

    Jan 09, 2023

  • Journal Article

    Dictionary-Assisted Supervised Contrastive Learning

    Proceedings of the Conference on Empirical Methods in Natural Language Processing, 2022

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    Text analysis in the social sciences often involves using specialized dictionaries to reason with abstract concepts, such as perceptions about the economy or abuse on social media. These dictionaries allow researchers to impart domain knowledge and note subtle usages of words relating to a concept(s) of interest. We introduce the dictionary-assisted supervised contrastive learning (DASCL) objective, allowing researchers to leverage specialized dictionaries when fine-tuning pretrained language models. The text is first keyword simplified: a common, fixed token replaces any word in the corpus that appears in the dictionary(ies) relevant to the concept of interest. During fine-tuning, a supervised contrastive objective draws closer the embeddings of the original and keyword-simplified texts of the same class while pushing further apart the embeddings of different classes. The keyword-simplified texts of the same class are more textually similar than their original text counterparts, which additionally draws the embeddings of the same class closer together. Combining DASCL and cross-entropy improves classification performance metrics in few-shot learning settings and social science applications compared to using cross-entropy alone and alternative contrastive and data augmentation methods.

    Area of Study

    Date Posted

    Oct 27, 2022

  • Journal Article

    Using Social Media Data to Reveal Patterns of Policy Engagement in State Legislatures

    State Politics & Policy Quarterly, 2022

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    State governments are tasked with making important policy decisions in the United States. How do state legislators use their public communications—particularly social media—to engage with policy debates? Due to previous data limitations, we lack systematic information about whether and how state legislators publicly discuss policy and how this behavior varies across contexts. Using Twitter data and state-of-the-art topic modeling techniques, we introduce a method to study state legislator policy priorities and apply the method to 15 US states in 2018. We show that we are able to accurately capture the policy issues discussed by state legislators with substantially more accuracy than existing methods. We then present initial findings that validate the method and speak to debates in the literature. The paper concludes by discussing promising avenues for future state politics research using this new approach.

    Date Posted

    Oct 18, 2022

  • Journal Article

    Most Users Do Not Follow Political Elites on Twitter; Those Who Do, Show Overwhelming Preferences for Ideological Congruity.

    Science Advances, 2022

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    We offer comprehensive evidence of preferences for ideological congruity when people engage with politicians, pundits, and news organizations on social media. Using four years of data (2016-2019) from a random sample of 1.5 million Twitter users, we examine three behaviors studied separately to date: (a) following of in-group vs. out-group elites, (b) sharing in-group vs. out-group information (retweeting), and (c) commenting on the shared information (quote tweeting). We find the majority of users (60%) do not follow any political elites. Those who do, follow in-group elite accounts at much higher rates than out-group accounts (90% vs. 10%), share information from in-group elites 13 times more frequently than from out-group elites, and often add negative comments to the shared out-group information. Conservatives are twice as likely as liberals to share in-group vs. out-group content. These patterns are robust, emerge across issues and political elites, and regardless of users' ideological extremity.

    Date Posted

    Sep 30, 2022

  • Journal Article

    Election Fraud, YouTube, and Public Perception of the Legitimacy of President Biden

    Journal of Online Trust and Safety, 2022

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    Skepticism about the outcome of the 2020 presidential election in the United States led to a historic attack on the Capitol on January 6th, 2021 and represents one of the greatest challenges to America's democratic institutions in over a century. Narratives of fraud and conspiracy theories proliferated over the fall of 2020, finding fertile ground across online social networks, although little is know about the extent and drivers of this spread. In this article, we show that users who were more skeptical of the election's legitimacy were more likely to be recommended content that featured narratives about the legitimacy of the election. Our findings underscore the tension between an "effective" recommendation system that provides users with the content they want, and a dangerous mechanism by which misinformation, disinformation, and conspiracies can find their way to those most likely to believe them.

    Date Posted

    Sep 01, 2022

  • Journal Article

    What We Learned About The Gateway Pundit from its Own Web Traffic Data

    Workshop Proceedings of the 16th International AAAI Conference on Web and Social Media, 2022

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    To mitigate the spread of false news, researchers need to understand who visits low-quality news sites, what brings people to those sites, and what content they prefer to consume. Due to challenges in observing most direct website traffic, existing research primarily relies on alternative data sources, such as engagement signals from social media posts. However, such signals are at best only proxies for actual website visits. During an audit of far-right news websites, we discovered that The Gateway Pundit (TGP) has made its web traffic data publicly available, giving us a rare opportunity to understand what news pages people actually visit. We collected 68 million web traffic visits to the site over a one-month period and analyzed how people consume news via multiple features. Our referral analysis shows that search engines and social media platforms are the main drivers of traffic; our geo-location analysis reveals that TGP is more popular in counties where more people voted for Trump in 2020. In terms of content, topics related to 2020 US presidential election and 2021 US capital riot have the highest average number of visits. We also use these data to quantify to what degree social media engagement signals correlate with actual web visit counts. To do so, we collect Facebook and Twitter posts with URLs from TGP during the same time period. We show that all engagement signals positively correlate with web visit counts, but with varying correlation strengths. For example, total interaction on Facebook correlates better than Twitter retweet count. Our insights can also help researchers choose the right metrics when they measure the impact of news URLs on social media.

    Date Posted

    Jun 01, 2022

  • Journal Article

    News Credibility Labels Have Limited Average Effects on News Diet Quality and Fail to Reduce Misperceptions

    Science Advances, 2022

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    As the primary arena for viral misinformation shifts toward transnational threats, the search continues for scalable countermeasures compatible with principles of transparency and free expression. We conducted a randomized field experiment evaluating the impact of source credibility labels embedded in users’ social feeds and search results pages. By combining representative surveys (n = 3337) and digital trace data (n = 968) from a subset of respondents, we provide a rare ecologically valid test of such an intervention on both attitudes and behavior. On average across the sample, we are unable to detect changes in real-world consumption of news from low-quality sources after 3 weeks. We can also rule out small effects on perceived accuracy of popular misinformation spread about the Black Lives Matter movement and coronavirus disease 2019. However, we present suggestive evidence of a substantively meaningful increase in news diet quality among the heaviest consumers of misinformation. We discuss the implications of our findings for scholars and practitioners.

    Date Posted

    May 06, 2022

  • Journal Article

    Why Botter: How Pro-Government Bots Fight Opposition in Russia

    American Political Science Review, 2022

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    There is abundant anecdotal evidence that nondemocratic regimes are harnessing new digital technologies known as social media bots to facilitate policy goals. However, few previous attempts have been made to systematically analyze the use of bots that are aimed at a domestic audience in autocratic regimes. We develop two alternative theoretical frameworks for predicting the use of pro-regime bots: one which focuses on bot deployment in response to offline protest and the other in response to online protest. We then test the empirical implications of these frameworks with an original collection of Twitter data generated by Russian pro-government bots. We find that the online opposition activities produce stronger reactions from bots than offline protests. Our results provide a lower bound on the effects of bots on the Russian Twittersphere and highlight the importance of bot detection for the study of political communication on social media in nondemocratic regimes.

    Date Posted

    Feb 21, 2022

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  • Journal Article

    What’s Not to Like? Facebook Page Likes Reveal Limited Polarization in Lifestyle Preferences

    Political Communication, 2021

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    Increasing levels of political animosity in the United States invite speculation about whether polarization extends to aspects of daily life. However, empirical study about the relationship between political ideologies and lifestyle choices is limited by a lack of comprehensive data. In this research, we combine survey and Facebook Page “likes” data from more than 1,200 respondents to investigate the extent of polarization in lifestyle domains. Our results indicate that polarization is present in page categories that are somewhat related to politics – such as opinion leaders, partisan news sources, and topics related to identity and religion – but, perhaps surprisingly, it is mostly not evident in other domains, including sports, food, and music. On the individual level, we find that people who are higher in political news interest and have stronger ideological predispositions have a greater tendency to “like” ideologically homogeneous pages across categories. Our evidence, drawn from rare digital trace data covering more than 5,000 pages, adds nuance to the narrative of widespread polarization across lifestyle sectors and it suggests domains in which cross-cutting preferences are still observed in American life.

    Area of Study

    Date Posted

    Nov 25, 2021

  • Journal Article

    Short of Suspension: How Suspension Warnings Can Reduce Hate Speech on Twitter

    Perspectives on Politics, 2023

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    Debates around the effectiveness of high-profile Twitter account suspensions and similar bans on abusive users across social media platforms abound. Yet we know little about the effectiveness of warning a user about the possibility of suspending their account as opposed to outright suspensions in reducing hate speech. With a pre-registered experiment, we provide causal evidence that a warning message can reduce the use of hateful language on Twitter, at least in the short term. We design our messages based on the literature on deterrence, and test versions that emphasize the legitimacy of the sender, the credibility of the message, and the costliness of being suspended. We find that the act of warning a user of the potential consequences of their behavior can significantly reduce their hateful language for one week. We also find that warning messages that aim to appear legitimate in the eyes of the target user seem to be the most effective. In light of these findings, we consider the policy implications of platforms adopting a more aggressive approach to warning users that their accounts may be suspended as a tool for reducing hateful speech online.

    Date Posted

    Nov 22, 2021

  • Journal Article

    Moderating with the Mob: Evaluating the Efficacy of Real-Time Crowdsourced Fact-Checking

    Journal of Online Trust and Safety, 2021

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    Reducing the spread of false news remains a challenge for social media platforms, as the current strategy of using third-party fact- checkers lacks the capacity to address both the scale and speed of misinformation diffusion. Research on the “wisdom of the crowds” suggests one possible solution: aggregating the evaluations of ordinary users to assess the veracity of information. In this study, we investigate the effectiveness of a scalable model for real-time crowdsourced fact-checking. We select 135 popular news stories and have them evaluated by both ordinary individuals and professional fact-checkers within 72 hours of publication, producing 12,883 individual evaluations. Although we find that machine learning-based models using the crowd perform better at identifying false news than simple aggregation rules, our results suggest that neither approach is able to perform at the level of professional fact-checkers. Additionally, both methods perform best when using evaluations only from survey respondents with high political knowledge, suggesting reason for caution for crowdsourced models that rely on a representative sample of the population. Overall, our analyses reveal that while crowd-based systems provide some information on news quality, they are nonetheless limited—and have significant variation—in their ability to identify false news.

    Date Posted

    Oct 28, 2021

  • Journal Article

    SARS-CoV-2 RNA Concentrations in Wastewater Foreshadow Dynamics and Clinical Presentation of New COVID-19 Cases

    • Fuqing Wu, 
    • Amy Xiao, 
    • Jianbo Zhang, 
    • Katya Moniz, 
    • Noriko Endo, 
    • Federica Armas, 
    • Richard Bonneau
    • Megan A. Brown
    • Mary Bushman, 
    • Peter R. Chai, 
    • Claire Duvallet, 
    • Timothy B. Erickson, 
    • Katelyn Foppe, 
    • Newsha Ghaeli, 
    • Xiaoqiong Gu, 
    • William P. Hanage, 
    • Katherine H. Huang, 
    • Wei Lin Lee, 
    • Mariana Matus, 
    • Kyle A. McElroy, 
    • Jonathan Nagler
    • Steven F. Rhode, 
    • Mauricio Santillana, 
    • Joshua A. Tucker
    • Stefan Wuertz, 
    • Shijie Zhao, 
    • Janelle Thompson, 
    • Eric J. Alm

    Science of the Total Environment, 2022

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    Current estimates of COVID-19 prevalence are largely based on symptomatic, clinically diagnosed cases. The existence of a large number of undiagnosed infections hampers population-wide investigation of viral circulation. Here, we quantify the SARS-CoV-2 concentration and track its dynamics in wastewater at a major urban wastewater treatment facility in Massachusetts, between early January and May 2020. SARS-CoV-2 was first detected in wastewater on March 3. SARS-CoV-2 RNA concentrations in wastewater correlated with clinically diagnosed new COVID-19 cases, with the trends appearing 4–10 days earlier in wastewater than in clinical data. We inferred viral shedding dynamics by modeling wastewater viral load as a convolution of back-dated new clinical cases with the average population-level viral shedding function. The inferred viral shedding function showed an early peak, likely before symptom onset and clinical diagnosis, consistent with emerging clinical and experimental evidence. This finding suggests that SARS-CoV-2 concentrations in wastewater may be primarily driven by viral shedding early in infection. This work shows that longitudinal wastewater analysis can be used to identify trends in disease transmission in advance of clinical case reporting, and infer early viral shedding dynamics for newly infected individuals, which are difficult to capture in clinical investigations.

  • Journal Article

    Twitter Flagged Donald Trump’s Tweets with Election Misinformation: They Continued to Spread Both On and Off the Platform

    Harvard Kennedy School (HKS) Misinformation Review, 2021

    View Article View abstract

    We analyze the spread of Donald Trump’s tweets that were flagged by Twitter using two intervention strategies—attaching a warning label and blocking engagement with the tweet entirely. We find that while blocking engagement on certain tweets limited their diffusion, messages we examined with warning labels spread further on Twitter than those without labels. Additionally, the messages that had been blocked on Twitter remained popular on Facebook, Instagram, and Reddit, being posted more often and garnering more visibility than messages that had either been labeled by Twitter or received no intervention at all. Taken together, our results emphasize the importance of considering content moderation at the ecosystem level.

  • Journal Article

    Testing the Effects of Facebook Usage in an Ethnically Polarized Setting

    Proceedings of the National Academy of Sciences, 2021

    View Article View abstract

    Despite the belief that social media is altering intergroup dynamics—bringing people closer or further alienating them from one another—the impact of social media on interethnic attitudes has yet to be rigorously evaluated, especially within areas with tenuous interethnic relations. We report results from a randomized controlled trial in Bosnia and Herzegovina (BiH), exploring the effects of exposure to social media during 1 wk around genocide remembrance in July 2019 on a set of interethnic attitudes of Facebook users. We find evidence that, counter to preregistered expectations, people who deactivated their Facebook profiles report lower regard for ethnic outgroups than those who remained active. Moreover, we present additional evidence suggesting that this effect is likely conditional on the level of ethnic heterogeneity of respondents’ residence. We also extend the analysis to include measures of subjective well-being and knowledge of news. Here, we find that Facebook deactivation leads to suggestive improvements in subjective wellbeing and a decrease in knowledge of current events, replicating results from recent research in the United States in a very different context, thus increasing our confidence in the generalizability of these effects.

    Area of Study

    Date Posted

    Jun 22, 2021

  • Journal Article

    Accessibility and Generalizability: Are Social Media Effects Moderated by Age or Digital Literacy?

    Research & Politics, 2021

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    An emerging empirical regularity suggests that older people use and respond to social media very differently than younger people. Older people are the fastest-growing population of Internet and social media users in the U.S., and this heterogeneity will soon become central to online politics. However, many important experiments in this field have been conducted on online samples that do not contain enough older people to be useful to generalize to the current population of Internet users; this issue is more pronounced for studies that are even a few years old. In this paper, we report the results of replicating two experiments involving social media (specifically, Facebook) conducted on one such sample lacking older users (Amazon’s Mechanical Turk) using a source of online subjects which does contain sufficient variation in subject age. We add a standard battery of questions designed to explicitly measure digital literacy. We find evidence of significant treatment effect heterogeneity in subject age and digital literacy in the replication of one of the two experiments. This result is an example of limitations to generalizability of research conducted on samples where selection is related to treatment effect heterogeneity; specifically, this result indicates that Mechanical Turk should not be used to recruit subjects when researchers suspect treatment effect heterogeneity in age or digital literacy, as we argue should be the case for research on digital media effects.

    Area of Study

    Date Posted

    Jun 09, 2021