On January 6, 2021, Twitter temporarily suspended Donald Trump’s account, requiring him to delete several of his tweets that rejected the election results and appeared to incite violence. Two days later, Twitter permanently suspended his account “due to the risk of further incitement of violence.” Trump tried to evade the ban by using the @Potus Twitter account that belongs to sitting U.S. presidents. His attempts were unsuccessful as Twitter immediately deleted almost all of his messages. This event is among many that show how the perverse use of social media can increase polarization (Gagliardone et al. Reference Gagliardone, Pohjonen, Beyene, Zerai, Aynekulu, Bekalu and Bright2016, 6-8; Takikawa et al. Reference Takikawa and Nagayoshi2017, 3148) and mobilize inter-group conflict (Bodrunova et al. Reference Bodrunova, Blekanov, Smoliarova and Litvinenko2019, 128-129). In order to address these adverse consequences, social media platforms such as Twitter, Facebook, Reddit, and others routinely engage in widespread bans of users (Peters Reference Peters2020; Guynn Reference Guynn2020; Spangler Reference Spangler2020).
Although account bans are a common measure against hate speech on social media, banning users can have unforeseen consequences such as the migration of banned users to more radical platforms (Livni Reference Livni2019). After Trump was banned, there were rumors that he himself might start using radical platforms such as Parler or GAB (Guynn Reference Guynn2021), or even start his own platform (Montanaro Reference Montanaro2021). Hence, even when bans reduce unwanted deviant behavior within one platform (Chandrasekharan et al. Reference Chandrasekharan, Pavalanathan, Srinivasan, Glynn, Eisenstein and Gilbert2017, 14-15), they might fail in reducing the overall deviant behavior within the online sphere.
With this in mind, we draw on political science theory to examine an alternative policy to banning users. More specifically, we test whether warning users of their potential suspension if they continue using hateful language might be able to reduce online hate speech. To do so, we implemented a pre-registered experiment on Twitter in order to test the ability of “warning messages” about the possibility of future suspensions to reduce hateful language online. More specifically, we identify users who are candidates for suspension in the future based on their prior tweets and download their follower lists before the suspension takes place. After a user gets suspended, we randomly assign some of their followers who have also used hateful language to receive a warning that they, too, may be suspended for the same reason.
Since our tweets aim to deter users from using hateful language, we design them relying on the three mechanisms that the literature on deterrence deems as most effective in reducing deviation behavior: costliness, legitimacy, and credibility. In other words, our experiment allows us to manipulate the degree to which users perceive their suspension as costly, legitimate, and credible.
As such, we aim to contribute to a better understanding of countering hate speech on social media. Although there is an increasing prevalence of research that explores the causes, dynamics, consequences, and detection of online hate speech (Müller and Schwarz Reference Müller and Schwarz2018), we still lack an understanding of the types and effects of interventions aimed at reducing hate-speech. On the one hand, scholars explore the effectiveness of measures that rely on censoring hateful content. On the other hand, there is a burgeoning literature on online speech moderation that, by drawing insights from the study of identity politics, proposes innovative interventions that reduce people’s likelihood of spreading hate speech (Munger Reference Munger2017, Reference Munger2020; Siegel and Badaan Reference Siegel and Badaan2020).
By testing the relative effectiveness of suspension warnings designed to highlight costliness, credibility, and legitimacy, we contribute to a better understanding of the exact mechanisms of deterrence that are most effective in reducing deviant behaviors online. To our knowledge, these mechanisms have not previously been analyzed in a naturalistic setting with real-time tracking of subject behavior.
This study also contributes to works that explore the impact of user bans by online social platforms. Although some studies show that bans are effective in reducing the overall levels of hate speech in one platform (Chandrasekharan et al. Reference Chandrasekharan, Pavalanathan, Srinivasan, Glynn, Eisenstein and Gilbert2017, 14-15), they rarely follow users' subsequent behavior and are, as such, not informative of the overall impact that bans can have on shaping the behavior of users who remain on the platform.
Our study provides causal evidence that the act of sending a warning message to a user can significantly decrease their use of hateful language as measured by their ratio of hateful tweets over their total number of tweets. Although we do not find strong evidence that distinguishes between warnings that are high versus low in legitimacy, credibility, or costliness, the high legitimacy messages seem to be the most effective of all the messages tested. We also test for a set of heterogeneity effects—number of followers, anonymity of the profile, level of Twitter engagement—and do not find evidence that the results are driven by any of these profile characteristics.Footnote 1
This reflection is organized as follows. First, we discuss the relevant theoretical underpinnings of our hypotheses and the literature on deterrence. Next, we present the details of our innovative experimental design, followed by our results. We then 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.
Deterring Hate Speech: Credibility, Costliness, and Legitimacy
There is a large body of literature that studies which types of interventions are most effective in reducing prejudice and conflict in real-world settings (Paluck and Green Reference Paluck and Green2009a; Broockman and Kalla Reference Broockman and Kalla2016; Munger Reference Munger2017; Siegel and Badaan Reference Siegel and Badaan2020). However, these works largely focus on inter-group dynamics, and draw on social psychological theories related to the salience of group identity.
In our study, we isolate components of interventions that are not related to identity dynamics. Instead, we explore factors that make a warning message effective in reducing hateful behavior. To begin, there is a large and still growing body of work from the literature on deterrence that provides evidence that sending warning messages in cyberspace represents an important avenue for deterring individuals from malevolent behavior (Wilson et al. Reference Wilson, Maimon, Sobesto and Cukier2015; Silic et al. Reference Silic, Silic and Oblakovic2016; Testa et al. Reference Testa, Maimon, Sobesto and Cukier2017).
Scholars argue that warning messages of punishment can take on two different forms of deterrence: general and specific. General deterrence is based on one’s vicarious experiences with punishment and punishment avoidance, whereas specific deterrence refers to the effect of one’s personal experiences with punishment and punishment avoidance (Stafford and Warr Reference Stafford and Warr1993, 127). In our study, our warning messages are meant to have a general deterrence effect because we make hateful users aware of the punishment other users were exposed to due to their use of hateful language.
When it comes to the deterrent effects of our warning messages, we are interested in the degree to which we are able to reduce users’ hateful language. Deterrence scholars distinguish between the ability of sanction threats to eradicate completely the deviant behavior (absolute deterrence), versus the effect of sanctions in reducing the severity and frequency of individual offending (restrictive deterrence) (Gibbs Reference Gibbs1968, 518; Jacobs Reference Jacobs2010, 423). Our experiment aims to test restrictive deterrence as we do not think that sending a single warning tweet to a hateful user would stop their use of hateful language completely.
Multiple factors are needed to make a warning message of punishment restrictively deter its targets from engaging in deviant behavior. As a first step, the deterring message should be conveyed to the target audience for it to be deterrent (Geerken and Gove Reference Geerken and Gove1974, 499), or based on Communication-Human Information Processing (C-HIP) Model (Conzola and Wogalter Reference Conzola and Wogalter2001, 312; Wogalter Reference Wogalter2006, 34-39), the warning should be communicated from the source (person or entity delivering the message) to the receiver. The delivery itself is not enough. It should also get the receiver’s attention. Once the message gets the receiver’s attention, the receiver should understand what the warning message says. Next, the warning message should change the receiver’s attitudes and beliefs about the costs and benefits of their deviant behavior (Beccaria Reference Beccaria1963, 59, 94; Paternoster Reference Paternoster1987, 174-175). Finally, the individual must understand what actions can be taken to avoid the costs of their unwanted behavior (Rogers Reference Rogers1975, 97-98) to change their behavior as a result of receiving a warning message.
In our study, we effectively deliver our warning message to hateful users by sending public tweets to their profiles.Footnote 2 In our context, punishment is account suspension. Since our tweets are different from a usual tweet that a user would receive from other users, and since the user gets notifications when they receive a tweet from another user, we presume that our tweets get their attention. We also avoid any type of jargon within the language of our warning tweets to avoid the risk that a user would misunderstand or not understand our tweets. We conduct manipulation checks to make sure that our tweets convey what we want them to convey.Footnote 3
We clearly express in our warning tweets the potential adverse consequences of the target users’ behavior—suspension from Twitter—and make them aware that people they followed faced these consequences. Having established the conditions that would make a warning message deterrent based on the literature, and based on the corroborating evidence from recent works that study the effect of surveillance warning banners on the behavior of trespassers (Stockman, Heile, and Rein Reference Stockman, Heile and Rein2015; Wilson et al. Reference Wilson, Maimon, Sobesto and Cukier2015), we pre-registered the following hypothesis:
H1. A tweet that warns a user of a potential suspension in the case of employing hate speech will lead that user to decrease their use of hateful language.
We design our messages based on the literature of deterrence. Theories on deterrence suggest three main channels. The first is the costliness, which emphasizes the influence of the perceptions of sanctions’ severity in generating effective deterrence (Cusson Reference Cusson1993; Gibbs Reference Gibbs1968; Paternoster Reference Paternoster1987). The second is credibility (Nagin Reference Nagin1998, 8), where the user’s conviction regarding the probability that a threat will occur affects how much they will be deterred from their unwanted behavior (Rogers Reference Rogers1975, 97). One factor that can make warnings credible is the authority of the source. Kiesler et al. (Reference Kiesler, Kraut, Resnick, Kittur, Kraut and Resnick2012, 133-134) point out that moderation attempts on online platforms by members who seem to deserve to be in the moderator position are considered as being more credible by other members. The third channel is the legitimacyFootnote 4 of the warning message. Sherman (Reference Sherman1993, 445) argues that the legitimacy of experienced punishment is essential for the acknowledgement of shame, which then conditions deterrence.
Based on these three different channels, we pre-registered three pairs of warning tweets. Each pair emphasizes high and low versions of each channel. For example, among the pair of warning tweets that we designed based on costliness, low-cost tweets trigger the costliness of the unwanted behavior less than the high-cost tweets do.Footnote 5
Deterrence as a Function of the Target’s Features
There are also reasons why we might expect to find differential effects based on user characteristics. We expect a greater cost from suspension for users who are more heavily invested in their profile (as measured by the number of tweets they post, the number of followers they have, or the age of their profile). Also, users who are anonymous (i.e., users who do not reveal their names or photos in their profile) would be expected to be less sensitive to our warning messages because anonymous users’ perceived risk of detection would be lower (Munger Reference Munger2017, 630-631).Footnote 6
Experimental Design
As we argue in the previous section, to effectively convey a warning message to its target, the message needs to make targets aware of the consequences of their behavior, and also make them believe that these consequences will be administered (Geerken and Gove Reference Geerken and Gove1974). Therefore, we designed experiments that would a) make Twitter users aware of the fact that their account could possibly be suspended, but at the same time, b) only sent these warnings to people who could credibly believe that their account could be suspended. To ensure that this second condition held, we limited our participant population to people who had previously used hateful language on Twitter and followed someone who actually had just been suspended.Footnote 7 In order to measure the effectiveness of our interventions, we could then compare the use of hateful speech by those who had received a warning with those who had not.
More specifically, we used a pre-registered design, the broad contours of which are illustrated in figure 1.Footnote 8 Our first step was to find accounts that could possibly be suspended during the term of our study. To identify such “suspension candidates”, we began by downloading 600,000 tweets on July 21, 2020 that were posted in the week prior and that contained at least one word from the hateful language dictionary created by Munger (Reference Munger2017).Footnote 9 During the period, Twitter was flooded by hateful tweets against the Asian and Black communities due to Covid and BLM protests, respectively (Kumar and Pranesh Reference Kumar and Pranesh2021; Ziems et al. Reference Ziems, He, Soni and Kumar2020).
Research design
Next, we downloaded the IDs of the 38,444 users who tweeted these tweets. We filtered these users to the 5,754 users who created their profile after January 1, 2020. Our reasoning here was that newly created users would be more likely to be suspended as compared to people with older accounts. We next downloaded all the followers of the 5754 users because we were expecting some of these users to get suspended and wanted to obtain the list of their followers before they got suspended. Over the course of fourteen days, 59 out of these 5,754 users did in fact get suspended. Out of the 59 users, we were able to download the follower lists of 48 of them before they were suspended. Out of those 48 users, we included only those with more than 50 followers to be able to randomize their followers into six treatment groups and a control group, which decreased the number of “seed users” from 48 users to 33 users with 39,659 followers. We downloaded the most recent 800 tweets of each of these 39,659 followers, and then calculated the percentage of each follower’s tweets that used at least one hateful term from Munger’s (Reference Munger2017) dictionary. We then filtered these followers to select only those who used a hateful term in at least 3% of their tweets over a month from July 4 to August 4. Munger (Reference Munger2017, 635) shows that among randomly sampled users, those who are at the seventy-fifth and higher percentile in terms of using hateful language have at least 3 percent of their tweets with hateful language, and calls the level of 3% the “regularly offensive threshold.” We label these followers as “hateful followers.” We filtered our 33 seed users to users with at least 7 “hateful” followers so that we could have at least one follower in each treatment condition from each seed user. This resulted in 27 suspended users with a total of 4,327 followers, who were then randomly assigned to one of our six treatment groups and to our control.Footnote 10
Figure 2 shows the distribution of the followers in all seven conditions (six treatment arms and one control arm to which we did not send a tweet). Most suspended users had somewhere between 100–500 hateful followers whose tweets rise above the “regularly offensive threshold,” although one suspended user had many more hateful followers compared to the others (1,889 followers).
Number of hateful followers per suspended user
Note: Names of the suspended users are anonymized to preserve privacy.
Table 1 shows the summary statistics of the suspended users’ 4,327 followers who tweet hateful language in at least 3% of their tweets. The mean proportion of hateful tweets is 6%, which is twice the ratio that Munger (Reference Munger2017) labels as a regular offensiveness threshold. Although the mean number of followers is very high, the median is much lower, reflecting the fact that the distribution is highly skewed towards accounts with lower numbers of followers. Activity is the daily number of tweets, which shows that the average user in our sample tweets eight times per day. Anonymity score is a variable that takes values of 0, 1, or 2. If a user’s anonymity score is equal to 0, the user has their own photo in their profile and their own name as their username. If the anonymity score is 1, they have either of the two. If it is 2, the user has neither and is considered completely anonymous.
Summary statistics on followers of the suspended users
After randomizing the followers into six treatment groups and a control group, we sent one of six tweets (representing the six theoretically informed treatment groups) from six separate accounts that we created.Footnote 11 We did not send any tweets to the control group.Footnote 12 The six tweets that we designed are meant to manipulate the costliness of the suspension in the eyes of the treated, the extent to which they perceive our warning as legitimate, and the degree to which they perceive our warning as credible. These messages can be seen in figure 3.
Treatment tweets
Note: As a manipulation check, we ran an MTurk experiment with a separate sample of fifty people to Refer to online appendix E for a more detailed discussion.
Results
We next present the key results of our experimental analyses; additional analyses described in our pre-registration plan can be found in the online appendix.Footnote 13 The coefficient plot in figure 4 shows the effect of sending any type of warning tweet on the ratio of tweets with hateful language over the tweets that a user tweets. The outcome variable is the ratio of hateful tweets over the total number of tweets that a user posted over the week and month following the treatment. The effects thus show the change in this ratio as a result of the treatment.
The effect of sending a warning tweet on reducing hateful language
Note: See table G1 in online appendix G for more details on sample size and control coefficients.
We find support for our first hypothesis: a tweet that warns a user of a potential suspension will lead that user to decrease their ratio of hateful tweets by 0.007 for a week after the treatment. Considering the fact that the average pre-treatment hateful tweet ratio is 0.07 in our sample, this means that a single warning tweet from a user with 100 followers reduced the use of hateful language by 10%. We suspect as well that these are conservative estimates, in the sense that increasing the number of followers that our account had could lead to even higher effects, as Munger (Reference Munger2017) and Siegel and Badaan (Reference Siegel and Badaan2020) show in their studies, to say nothing of what an official warning from Twitter would do.Footnote 14
The coefficient plot in figure 5 shows the effect of each treatment on the ratio of tweets with hateful language over the tweets that a user tweets. Although the differences across types are minor and thus caveats are warranted, the most effective treatment seems to be the high legitimacy tweet; the legitimacy category also has by far the largest difference between the high- and low-level versions of the three categories of treatment we assessed. Interestingly, the tweets emphasizing the cost of being suspended appear to be the least effective of the three categories; although the effects are in the correctly predicted direction, neither of the cost treatments alone are statistically distinguishable from null effects.
Reduction in hate speech by treatment type
Note: See table G2 in online appendix G for more details on sample size and control coefficients.
An alternative mechanism that could explain the similarity of effects across treatments—as well as the costliness channel apparently being the least effective—is that perhaps instead of deterring people, the warnings might have made them more reflective and attentive about their language use. Such a mechanism would be consistent with prior disinformation studies that demonstrated that nudging, flagging, or alerting users to the possibility of inaccuracy makes users more attentive to questions of accuracy (Pennycook et al. Reference Pennycook, Epstein, Mosleh, Arechar, Eckles and Rand2021). If that is the case, then perhaps our act of warning people impacted their behavior simply by causing them to be more reflective about their own actions, as opposed to motivating a change in behavior out of fear of possible punishment.
Discussion and Implications
Our results show that only one warning tweet sent by an account with no more than 100 followers can decrease the ratio of tweets with hateful language by up to 10%, with some types of tweets (high legitimacy, emphasizing the legitimacy of the account sending the tweet) suggesting decreases of perhaps as high as 15%–20% in the week following treatment. Considering that we sent our tweets from accounts that have no more than 100 followers, the effects that we report here are conservative estimates, and could be more effective when sent from more popular accounts (Munger Reference Munger2017).
In reducing hateful language, our paper builds on works from political science that explore various interventions that reduce intergroup prejudice and conflict (Paluck and Green Reference Paluck and Green2009b; Samii Reference Samii2013; Simonovits, Kezdi, and Kardos Reference Simonovits, Kezdi and Kardos2018; Kalla and Broockman Reference Kalla and Broockman2020). These strategies mostly rely on intergroup contact theory (Pettigrew Reference Pettigrew1998), on interpersonal conversations (Kalla and Broockman Reference Kalla and Broockman2020), or on making subjects play a perspective taking game where they practice thinking from the perspective of the outgroup members (Simonovits, Kezdi, and Kardos Reference Simonovits, Kezdi and Kardos2018) in order to decrease antipathy towards other groups.
A recently burgeoning literature shows that online interventions can also decrease behaviors that could harm the other groups by tracking subjects' behavior over social media. These works rely on online messages on Twitter that sanction the harmful behavior, and succeed in reducing hateful language (Munger Reference Munger2017; Siegel and Badaan Reference Siegel and Badaan2020), and mostly draw on identity politics when designing their sanctioning messages (Charnysh et al. Reference Charnysh, Lucas and Singh2015). We contribute to this recent line of research by showing that warning messages that are designed based on the literature of deterrence can lead to a meaningful decrease in the use of hateful language without leveraging identity dynamics. This is important because interventions that rely on identity dynamics require the knowledge of the target user’s identity to be effective (Munger Reference Munger2017; Siegel and Badaan Reference Siegel and Badaan2020). However, obtaining such knowledge is not always feasible, as it is not uncommon for people on social media platforms such as Twitter to have anonymous profiles. Even when profiles are non-anonymous, labeling them to design an effective intervention that is based on the identity of the target user may be costly and time consuming.
Our findings suggest, therefore, that one option for reducing hate speech on Twitter would be to warn users who have reason to suspect that they might be at risk of being suspended by Twitter for using hateful language. In our experiment, this “at risk” category was based on the three-fold combination of finding users who themselves use hateful language and followed someone who got suspended from the platform for using hateful language and alerting them to the fact that the person they followed (known in Twitter parlance as a “friend”) had been suspended.
How might this be done? Two options are worthy of discussion: relying on civil society or relying on Twitter. Our experiment was designed to mimic the former option, with our warnings mimicking non-Twitter employees acting on their own with the goal of reducing hate speech/protecting users from being suspended. From our intervention, it seems that at a bare minimum, such warnings can result in a short-term reduction in hate speech on Twitter, which would seem to be normatively desirable. And while we did not find longer-term effects from a single warning, it is possible that different variations of this stimulus (e.g., multiple warnings over an extended time period) could have a longer-term effect. But even if not, the cumulative effect of short-term reductions in hate speech—if new warnings were issued to new people with regularity—would still reduce hate speech on the platform.
The question, of course, is how such a program could be implemented at the scale of Twitter. It did take a non-trivial amount of work and technical skill for us to design and implement our interventions. While it is certainly possible that an NGO or a similar entity could try to implement such a program, the more obvious solution would be to have Twitter itself implement the warnings. After all, Twitter has access to all of the necessary data: the company knows exactly who has been suspended and when, who their followers are, and whether or not those users have crossed the “regularly offensive” threshold. Moreover, Twitter has the capacity to completely automate this process, which means that it can be applied at scale; it also means that Twitter could easily run much more extensive versions of our study to hone in on the most effective types of warnings.
Indeed, Twitter has also recently shared publicly results from its own testing of a different form of warning. More specifically, the company reported “testing prompts in 2020 that encouraged people to pause and reconsider a potentially harmful or offensive reply—such as insults, strong language, or hateful remarks—before Tweeting it. Once prompted, people had an opportunity to take a moment and make edits, delete, or send the reply as is.”Footnote 15 This appears to result in 34% of those prompted electing either to review the Tweet before sending, or not to send the Tweet at all.
We note three differences from this endeavor. First, in our warnings, we try to reduce people’s hateful language after they employ hateful language, which is not the same thing as warning people before they employ hateful language. This is a noteworthy difference, which can be a topic for future research in terms of whether the dynamics of retrospective versus prospective warnings significantly differ from each other. Second, Twitter does not inform their users of the examples of suspensions that took place among the people that these users used to follow. Finally, we are making our data publicly available for re-analysis.
We stop short, however, of unambiguously recommending that Twitter simply implement the system we tested without further study because of two important caveats. First, one interesting feature of our findings is that across all of our tests (one week versus four weeks, different versions of the warning—figures 2 (in text) and A1(in the online appendix)) we never once get a positive effect for hate speech usage in the treatment group, let alone a statistically significant positive coefficient, which would have suggested a potential backlash effect whereby the warnings led people to become more hateful. We are reassured by this finding but do think it is an open question whether a warning from Twitter—a large powerful corporation and the owner of the platform—might provoke a different reaction. We obviously could not test for this possibility on our own, and thus we would urge Twitter to conduct its own testing to confirm that our finding about the lack of a backlash continues to hold when the message comes from the platform itself.Footnote 16
The second caveat concerns the possibility of Twitter making mistakes when implementing its suspension policies. Now, of course, these policies already exist and are being implemented, so mistakes in the process already cause harm to users whose accounts are incorrectly suspended. However, implementing the warning system we tested in our experiment would in a sense be broadcasting the fact of that suspension—and attributing a reason for it—to a larger number of users. We were careful in our experiments to say that we suspected the account was suspended because of hateful language (which was absolutely true—we did suspect this but did not know definitively), but coming from Twitter such ambiguity would likely be less credible.Footnote 17 Thus it would be important to weigh the incremental harm that such a warning program could bring to an incorrectly suspended user (importantly, beyond the harm that the already existing suspension policy is causing) versus the benefit of the incremental decrease in hate speech on the platform. We suspect the dispersed benefits would outweigh the concentrated harm, but in order to definitively feel comfortable with this conclusion we would want to see Twitter’s data about how often accounts that are suspended for hate speech are found to have been incorrectly suspended, as well as whether there are disproportionate numbers of incorrect suspensions across different socio-demographic groups within society. Nevertheless, it is worth considering whether it would be better for Twitter—should it decide to test/implement a version of what we have done—to anonymize the suspended user in the warning tweet (e.g., “someone you follow was suspended” as opposed to the “@[user] was suspended” we employed). This might help mitigate the potential harm, but such an approach would clearly need to be tested to see if it still has the same impact on reducing hateful speech.
While our experiment was conducted solely on Twitter, there is nothing inherent about the idea of using warnings of suspended friends to try to reduce hateful speech that limits such an approach to Twitter. However, it is worth highlighting that there are particulate affordances of Twitter that make the platform amenable to this sort of intervention, namely the fact that the users are enmeshed in networks and that activity on the platform is largely public. The former raises our expectation that people will care that user X was suspended because the user already has a previous relationship with user X (i.e., the user chose to follow user X), so it might be the case that simply learning some random user was suspended (on a platform such as Reddit where there are not follower relationships) might not be as effective. The fact that Twitter is a public platform may also have made users less surprised to see a warning from a random account such as ours, which might not be the case on a platform where users are more accustomed to thinking their posts are private, such as Facebook, although this concern might be less of an issue if the message is coming from the platform itself.Footnote 18
Despite these caveats, our findings suggest that hate-speech moderations can be effective without priming the salience of the target users’ identity. Explicitly testing the effectiveness of identity versus non-identity motivated interventions will be an important subject for future research.
Acknowledgements
Yildrim and Tucker designed the research; Yildrim performed the research; Yildrim, Nagler, Bonneau, and Tucker planned the analyses; Yildrim analyzed data and wrote the first draft of the paper, and all authors contributed to revisions. The authors are thankful to the New York University Center for Social Media and Politics (CSMaP) weekly meetings and the New York University Comparative Politics Workshop for their helpful feedback. The Center for Social Media and Politics for New York University is generously supported by funding from the National Science Foundation, the John S. and James L. Knight Foundation, the Charles Koch Foundation, the Hewlett Foundation, Craig Newmark Philanthropies, the Siegel Family Endowment, and New York University’s Office of the Provost.
Supplementary Materials
To view supplementary material for this article, please visit http://doi.org/10.1017/S1537592721002589.
Appendix A. Missing Observations
Appendix B. Power Analysis
Appendix C. Heterogeneous Treatment Effects
Appendix D. Heterogeneous Treatment Effects with Continuous Variables
Appendix E. Manipulation Checks for Our Warning Tweets
Appendix F. Alternative Outcome Variable
Appendix G. Detailed Tables for the Figures in the Paper
Appendix H. Treatment Tweets and Profiles that Sent Them
Appendix I. Pre-Registered Hypotheses and Their Theoretical Justifications
Appendix J. Dictionary of Hateful Words
