How News Organizations Coordinate, Select, and Edit Content for Social Media Platforms: A Systematic Literature Review

ABSTRACT Social media platforms (SMP) are increasingly important for news organizations to reach (wider) audiences. The accompanying platformization of journalism has raised concerns that the adaptation to social media characteristics leads to trivialization and softening of news. Often triggered by these normative considerations, journalistic content production for social media has attracted much scholarly attention. To date, however, these studies lack synthesis. To fill this research gap, this paper reports on a systematic literature review (SLR) of 156 publications to summarize and discuss current knowledge about how news organizations select, edit, and coordinate content for SMP. The results show that content is not generally softened on SMP such as Facebook, Twitter, or Instagram. Rather, news organizations develop strategies to balance their professional standards with social media characteristics. Differences appear, among others, in organizational traits such as revenue model and between SMP. Building on these results, the study concludes with paths to develop future research.

are involved (e.g., social media editors) and how they interact (e.g., during daily conferences).Of course, the production of SMP content does not end with its publication.Especially in the context of digital journalism, audiences are involved in the continued distribution and interpretation of content (Domingo et al. 2008), such as by sharing and commenting on it.However, these last stages of news production shift the emphasis from journalistic actors to their audiences.Therefore, distribution and interpretation were not included in the current study.
In line with Carr and Hayes (2015), social media platforms are understood as disentrained, persistent online channels for mass communication, facilitating interaction that derives "value primarily from user generated content" (49).Instant messengers such as Telegram and WhatsApp are also included, as they, too, allow for disentrained communication (Carr and Hayes 2015, 50), although their relevance for news use has recently dropped slightly (Newman et al. 2022, 24).Following the definitions of Alonso et al. (2019), a news outlet is understood as "an original editorial product (e.g., a newspaper, TV newscast, online news site or radio station) with an identifiable focus on providing news" (16).News outlets function within a news organization, that is, a "company or other grouping that provides financial resources and editorial or logistical infrastructure (such as physical space and data networks)" (Alonso et al. 2019, 17).Thus, the phrase (news) outlet is used to describe an organization's social media desk.In turn, if in the SLR an author refers to (characteristics of) the entire organization (e.g., its ownership), the term (news) organization is used.Importantly, this paper is not restricted to "news," that is, information about, analysis of, or commentary on current affairs (Alonso et al. 2019, 16).Instead, content is used because studies have shown that news organizations also publish non-news items such as dancing videos and scenic pictures on SMP (e.g., Vázquez-Herrero, Direito-Rebollal, and López-García 2019).Additionally, from the audience's point of view, "news" has become a hazy concept (Vraga et al. 2016), so it is important to consider all of the content that news outlets provide.
To capture the research field comprehensively and identify potential relations between study design and outcomes, this analysis should not only synthesize the results regarding news organizations' SMP news production but also consider study characteristics.This includes applied theories and methods as well as the research context (e.g., the platform under investigation, year and country of data collection).
The main goal of this study is therefore to answer the following questions: RQ1: Which contexts, theories, and methods are prevalent in research on news organizations' content production for social media platforms?
RQ2: What have previous researchers found in terms of how news organizations coordinate, select, and edit content for social media platforms?
To answer these research questions, this SLR quantitatively and qualitatively examines and synthesizes the results of 156 articles published between 2008 and 2022 on news organizations' SMP content production.The remainder of the paper is organized as follows.The next section describes the multi-stage sampling process and outlines the analysis of the selected publications.Hereafter, the results on news organizations' SMP content production show that content on these platforms is, contrary to the above-mentioned concerns, often not softened.
Instead, news organizations develop strategies to balance their professional standards with social media characteristics.Differences occur, among others, in organizational characteristics (e.g., revenue models) and between the platforms themselves.Lastly, the SLR concludes with a summary and discussion of the results and outlines paths for research that could further enlighten our understanding of journalistic content production for SMP.

Method
SLRs are appropriate for highlighting and analyzing the available data on a subject and relating it to study characteristics (Cooper 1998).The current SLR synthesizes primary publications on news organizations' SMP content production that were released between 2008-the year that research on journalism and social media "jumped" (Lewis and Molyneux 2018, 13)-and 2022, the year in which the SLR was carried out.
To ensure intersubjectivity and transparency, the review was conducted in accordance with established guidelines (research protocol, predefined eligibility criteria, a systematic and comprehensive database search; see Page et al. 2021;Paré et al. 2015), which are outlined in the following sections.The sampling procedure, review protocol, and sample overview are available in the appendix.The complete study materials, including category system and R scripts, are accessible on the Open Science Framework (https://tinyurl.com/smpjourno).

Sampling
The sampling was guided by a review protocol (see Appendix A) consisting of the databases and search strings used; search time; and inclusion criteria.The protocol was validated by determining whether the search yielded three studies that had previously been selected as crucial by applying the inclusion criteria described below (Haim et al. 2021;Lischka 2021;Walters 2022).The three studies investigate what (Haim et al. 2021) and why (Lischka 2021;Walters 2022) news organizations publish on social media, but apply different theories and methods and are situated in different empirical contexts.Using these studies as a validation check ensured that the review protocol yielded relevant studies.
Subsequently, the sampling process took place in four steps (see Appendix B).First, in February 2022, an extensive database search was conducted.As the boundaries of journalism research are not clear-cut (Deuze and Witschge 2018), both specific (EBSCO Communication and Mass Media Complete) and interdisciplinary databases (Scopus, SpringerLink) were used.Google Scholar acted as an additional repository so as not to miss any studies that had recently been published.The search string combined an exhaustive list of keywords covering all dimensions of the research interest (news organization, content production, social media platform).As it unavoidably included broader terms such as "media" or "news," the initial number of results was quite high (n = 24,405).Therefore, the first selection was reduced to a screening of titles, abstracts, and keywords to assess whether a publication concerned (1) journalistic (2) content production (3) for SMP.This step left 511 publications.For the final stages three and four, a 5-point score system was developed based on the inclusion criteria, wherein only publications that were released in a peer-reviewed journal, conference proceeding, or as a book chapter (+1); were published in English (+1); concerned content production (+1) by a news organization (+1) for SMP (+1); and thus received a total of 5 points were included.During the third stage, this score was applied to the publications' abstracts, resulting in a preliminary sample of 277 studies.While skimming through the full texts, the score was applied once more, but only with the content-related criteria.After this fourth stage, the final sample consisted of 156 publications.During the last two stages, most studies were excluded because they discussed news sharing by audiences (e.g., Larsson 2018) with SMP as journalistic sources (e.g., Brandtzaeg and Domínguez 2018) or individual journalists' use of SMP (e.g., Lasorsa, Lewis, and Holton 2012).

Analysis
Following previous reviews of SMP communication research (Zhang and Leung 2015) and SMP news sharing (Kümpel, Karnowski, and Keyling 2015), the analysis was divided into two parts due to the heterogeneity of the sampled studies.First, a quantitative analysis provided information about the manifest content of the publications under investigation (RQ1).The author coded the publications with regard to contexts (e.g., year of publication and data collection, investigated platform) and theoretical (i.e., [number of] theories employed) as well as methodological (e.g., methodological paradigm, specific methods) characteristics.These categories were assigned numerical codes and analyzed descriptively.Second, qualitative analysis was used to synthesize the studies' results on how news organizations coordinate, select, and edit content for SMP (RQ2).Specifically, text-based categories were developed deductively (selecting, editing, coordinating; influences from SMP characteristics; SMP audiences; micro-level factors such as journalistic role perception; meso-level factors such as editorial guidelines; macro-level factors such as media system) and inductively (SMP activity, SMP strategy) to code the relevant results of the included studies.These categories were investigated via techniques of qualitative content analysis.The coded text parts were read and interpreted iteratively to structure and summarize the studies' results (Mayring 2015).The goal was not only to identify overarching trends but also to derive explanations for similarities and differences in both internal factors (e.g., characteristics of the SMP or the outlets under investigation) and study design (e.g., year of data collection or method).The results of these analyses are discussed in the next section.When referring to publications in the sample, the ID assigned in the Sample Overview (Appendix C) is used.However, if publications are quoted directly, the complete reference is provided.

Results
RQ1: Prevalent Contexts, Theories, and Methods RQ1 asked about the included studies' prevalent contexts, theories, and methods.It is answered by reporting the results of the quantitative analysis.Considering contexts first, in a brief overview of the 156 sampled publications, the SLR reveals growing attention on SMP content production during the study period (Figure 1).The number of publications consistently increased until 2021, although the trend for the year of data collection indicates more fluctuation.
Furthermore, the relative majority of first authors is affiliated with an institution in the US (28.8%).However, this share is not as high as in other reviews of SMP news (use) (Kümpel, Karnowski, and Keyling 2015;Segado-Boj 2020).Moreover, only one fourth of the studies collected data solely in the US, with a comparison of data from two or more countries more common (33.3%).
Regarding platform use, Twitter (50.6%) and Facebook (39.1%) are the most investigated platforms, which resembles the findings of previous SLRs (Segado-Boj 2020; Zhang and Leung 2015).Although the share of studies investigating Instagram and TikTok increased over time, Twitter and Facebook have not particularly lost relevance.However, the steady scholarly attention on these platforms only partly corresponds with current usage trends: While Instagram and TikTok have become more important for news use, Twitter and Facebook have lost relevance (Newman et al. 2022, 24).Therefore, especially Twitter's prominence might be both a matter of relevance for journalists and news organizations (Hermida 2016) and the platform's (long-time) comparatively easy accessibility for researchers (Tromble 2021).
With regard to programs, most publications address the selection (75%) and editing (62.8%) of SMP content.In contrast, coordination is considered in a smaller share of the sample (12.8%).Importantly, around one third of studies investigate SMP content production on a specific topic, such as anti-racist protests (e.g., 24) or gender representation (e.g., 15).
In congruence with the different research contexts, there is a diversity of theories.A majority of publications (76.6%) use at least one specific theory lens.The studies employ both original theories from the journalism field, such as news value theory (e.g., 10), agenda setting (e.g., 73), and gatekeeping (e.g., 103), and borrowed theories from related fields, such as Bourdieu's field theory (135) and actor-network-theory (154).
Turning to the relevance of single theories, (social) media logic (14.1%) ranks first and framing (11.5%) second.This inherently heterogeneous approach (Matthes 2009) is applied by more than one third of studies that investigate how a specific topic is presented on SMP.News value theory ranks third (7%), as many authors set out to investigate potentially changing news values (e.g., 9).Adding to the diversity of theoretical approaches, the "Other" category constitutes 43.6% of the studies.Examples in this category include game theory (78) and rhetorical arena theory (112).
A short investigation of temporal patterns reveals interesting differences.On the one hand, traditional theories such as framing, gatekeeping, and agenda setting are evergreens.News value theory, for instance, had shares over 10% in 2013 and 2016, but also in 2021.On the other hand, social media logic is a rising star.While it was nearly irrelevant in earlier studies, it has mainly had shares of 10% or more since 2014.This development indicates a growing scholarly awareness of SMPs' impacts on news production.
Concluding this section is an outline of the methods employed.The 156 publications under consideration report on a total of 181 empirical studies, which is indicative of the prevalence of multi-method designs.Only 13 of the sample's studies are case studies, that is, focus on a single news organization on a single platform.This is contrasted by the majority of studies that examine various platforms and/or organizations.Looking at the specific methods, quantitative content analyses are most popular, adopted in nearly two thirds of the studies (62.5%).In second place are qualitative interviews with social media editors or management staff (17.3%).In contrast, there are hardly any standardized surveys (1.28%) or ethnographic studies (2.56%).The employed methods thus correspond with the prominence of the selecting and editing programs: especially the occurrence of content analyses implies a focus on production outcomes instead of the preceding processes, which has to be taken into account for the qualitative analysis that follows.The results for RQ1 are summarized in Table 1.

RQ2: How News Organizations Coordinate, Select, and Edit Content for SMP
This section synthesizes the results on how news organizations coordinate, select, and edit content for SMP (RQ2).During the analysis, the goals and intentions that news Quantitative content analysis (62.5%), Qualitative interview (17.3%),Ethnography (2.56%) a Multiple platforms, theories, and programs could be coded per article.b To calculate these shares, the categories "methodological paradigm" (qualitative/quantitative) and "method" (content analysis/survey, interview/observation, or ethnography) were cross-tabulated.
organizations pursue when distributing content on SMP emerged as an important aspect.
It is insightful to start with a closer look at these general strategies, as they also inform content production.

General SMP Strategies in News Organizations
In assessing the included studies, three strategic patterns became apparent: non-strategic use and, as Sehl, Cornia, and Nielsen (2021) called it, "off-site" versus "on-site" strategies (3).First, according to some authors (e.g., 6, 15, 66, 87), the news organizations under study do not have a strategy for SMP or at the very least "don't seem to be using it in innovative ways" (Armstrong and Gao 2010, 232).Commonly, indicators for this conclusion are missing differences between platforms with regard to the content that an organization publishes or automated posting of headlines from the organization's website without re-editing them for SMP (e.g., 15,31,33,39,44,56).Second, many outlets pursue a traffic-oriented "on-site strategy" (e.g., 27, 39, 55): they want the audience to stop scrolling through SMP and go to their organizations' websites instead (Sehl, Cornia, and Nielsen 2021, 4).Therefore, these posts advertise a broadcaster's show or link to an article on a newspaper's website.In this regard, SMP are more a gateway than an additional outlet.In general, this strategy is prevalent on all platforms that incorporate linking features, including Twitter (e.g., 21, 55), Facebook (e.g., 20, 97), and Instagram's Story (90, 142) and, similarly, Facebook's Live feature (122).There is a tendency for private outlets to focus more on this strategy (e.g., 3, 74, 96, 126), as they monetize visits of their own website through advertisements (Sehl, Cornia, and Nielsen 2021, 15).However, it is also crucial for public or state-financed media (e.g., 9, 23, 59), as they might feel more pressure from the public and lawmakers not to use SMP as their primary outlet (126,142).
Third, "off-site strategies" refer to any actions taken to increase participation and draw in (new) audiences directly on SMP (Sehl, Cornia, and Nielsen 2021, 4).Engagement with content tailored to a (young) target audience and interaction with that audience on the platform are more crucial than traffic generation.The most obvious example of these strategies are "social journalism" outlets (Hendrickx 2021): SMP-native outlets whose content is produced only for SMP (2).However, other outlets employ off-site strategies, too, as they try to become accessible and transparent (3, 20), to establish popularity and a familiar and positive brand image-especially among younger audiences (e.g., 17,19,35,143).This kind of branding, with activities aimed at a "recognizable and trustworthy badge of origin" (Chan-Olmsted and Kim 2001, 75), also includes promoting the news organization itself.For example, outlets might publish behind-the-scenes-content from the newsroom (55, 57, 66).Importantly, especially for legacy organizations, branding also implies conserving their brand image as providers of relevant and correct information (e.g., 21,26,32).
These strategies are not mutually exclusive, as interaction with the audience, for instance, may also generate a post's popularity and therefore enhance traffic.Similarly, interacting with new audiences on SMP may be driven by the objective to convert them into long-term customers who later access the content on-site (Sehl, Cornia, and Nielsen 2021, 15).Additionally, a lot of research does not measure whether the content was produced only for SMP or linked to news organizations' own websites, making it difficult to pinpoint a strategy for all organizations investigated by the sampled studies.
The overview of strategies, however, contextualizes the following results on coordinating, selecting, and editing.

Coordinating
This section presents the results on coordinating, or the procedures and responsibilities within newsrooms that organize which and how content is published on SMP.Specifically, this section focuses on social media editors (SME) and their different competencies and embeddedness in the content production process.
When news organizations started their presence on SMP, "everyone was expected to help out" with running the accounts on these platforms (Lysak, Cremedas, and Wolf 2012, 199).However, organizations soon started hiring SME (also titled social media managers or audience/engagement editors; see 99, 107, 118), who are central to many studies concerning the coordinating program.The introduction of SME is closely connected with the growing importance of SMP for news organizations (90,118).Therefore, they were not only hired in larger newsrooms but also in smaller (local) organizations ( 107), which often have less resources but might depend more on the revenue that comes through SMP (126,139).
Differences occur with regard to the competencies and embeddedness of SME in the content production process.On the one hand, some publications report that SME are considered mere administrators and "delegates of the editors" (Said-Hung et al. 2014, 6).In these cases, they only post content that has already been selected by journalists and editors, often just copying the headlines from the news organization's website (see also 41,58,82).These rather constrained SME competencies are primarily found in quality legacy organizations, which could be explained by the aforementioned strategy to protect brand identity: to maintain a serious and credible image, the decisionmaking authority over selecting and editing for SMP lies with the (senior) legacy editors (David, Tandoc, and Katigbak 2019, 337).Another aspect that limits SMEs' competencies is conflict between traffic, engagement, and SMP content.While SME are potentially more inclined toward an off-site strategy and want to increase likes and interaction on SMP, their editor-in-chief may be more concerned with an on-site strategy and thus want to steer clear of content that is so engaging that it prevents users from leaving SMP (50, 140).
On the other hand, SME seem to be influential figures in many organizations that the included studies investigate.Rather unsurprisingly, these powerful SME are mostly observed in (legacy-owned) social journalism organizations to pursue off-site strategies.Here, SME are integrated into the whole production process because they produce content primarily or only for SMP (41,140).However, other studies note SME with farreaching competences in public and private legacy organizations as well (99,132,140).In these cases, SME not only select and edit the content posted to SMP but also act as "institutional change agents" (Neilson and Gibson 2022).Specifically, they transfer their knowledge on audience preferences and engaging content to legacy editors and journalists, thereby shaping their selection and editing decisions as well (50,99,107).SME sometimes even consider themselves an "elite unit with unique knowledge since they are the only ones who understand the social 'language'" (Tsuriel et al. 2021(Tsuriel et al. , 1991)).Accordingly, it appears that the more powerful SME are, the more likely the content is to be oriented toward SMP and their audiences (41,99,140,153).
These results notwithstanding, it would oversimplify the situation to state that the characteristics of SMP do not affect news outlets' decisions about what to publish.For example, studies investigating content through the lens of news factors show that factors such as conflict, proximity, or negativity are most prevalent (e.g., 8, 50, 78), all of which are considered to contribute to the "shareability" of content (Harcup andO'Neill 2017, 1480).When repurposing already published content for SMP, SME often emphasize these elements (78,132).This technique might be a way of reconciling metrics-driven content output with journalistic standards: outlets select topics such as politics for SMP, but change the focus to attract more attention.
Beyond these general findings, there are noticeable differences, first of which concerning platforms.Although studies investigating several platforms partly highlight only small differences (e.g., 6, 57, 103), there is a relatively clear pattern in the bigger research picture.Specifically, a decision can be made between platforms like Twitter, which itself is a "news medium," and those with a "social character" (Groot Kormelink and Costera Meijer 2014, 637) like Facebook, Instagram, and TikTok.On the latter SMP, outlets focus-albeit sometimes only slightly-more on trivia, lifestyle, sports, or nonnews topics (e.g., 4, 34, 36 50, 74, 84, 112, 155).On Twitter, politics and current affairs appear to be more prominent (e.g., 38, 57, 72, 96, 103, 125, 152).One reason for these differences might be the platforms' audience: According to the authors or their interviewees, Twitter's audience consists mainly of journalists or politicians (44,78).In contrast, the audiences of Facebook, Instagram, and TikTok are perceived to be younger and less news-interested (e.g., 19,63,131).Accordingly, the aforementioned off-site strategy associated with self-promotion content is common on SMP like Instagram or TikTok (e.g., 46,54,108,143).On these SMP, outlets might assume an audience that is not yet familiar with the brand, but can be attracted with entertaining non-news content (Piñeiro-Otero and Martín-Pena 2023, 13; Vázquez-Herrero, Negreira-Rey, and López-García 2022, 14).

Editing
Turning now to the editing program, this section summarizes evidence on the presentation of content on SMP.As with selecting, general insights are outlined first, then differences in platforms and outlets.Consistent with the aforementioned inclination toward (political) news topics, studies investigating the tone of SMP content often describe it as "serious" (Ameli and Molaei 2020, 988) and rather neutral instead of opinionated (e.g., 28, 29, 103, 138).Disclosure, personification, and subjective tone are uncommon (e.g., 20, 21, 22, 30, 39, 149) and mostly used in specific formats, such as behind-thescenes content (e.g., 12, 58, 90, 120, 135).
Next to perceived audience and platform styles, the features of SMP appear to influence editing.Consider, for example, the possibility of linking.On the one hand, the use of links is an inherent structural feature of Twitter (Hermida and Mellado 2020, 880).Consequently, many outlets pursue an on-site strategy on this platform, mainly to link to their websites or promote their offline program (e.g., 32, 37, 85, 94, 121, 141).On the other hand, Instagram and especially TikTok make it hard to include links.This may trigger the production of native content and therefore off-site strategies (e.g., 54,108,131,144).
Differences between organizations are also apparent.There is a tendency for the outlets of commercial (tabloid) organizations to use more textual features such as exclamation marks or emojis and a more subjective tone (28,41,44,50,58,62,148).This might also result from the inclination toward lighter topics (Welbers and Opgenhaffen 2019, 56).Again, there are some ambivalences.For example, broadsheet, tabloid, and public broadcaster outlets use emojis in similar ways (100) and engage in the "softening" (i.e., more emotional and personal reporting; Reinemann et al. 2012, 238) of their content (74,84,134).
Lastly, it seems that outlets have increased their platform orientation in terms of selecting and editing over the years.Especially interview studies show that over time and with the introduction of SME, knowledge about how to improve posts' performance has increased (Walters 2022, 13; see also 78,90,107).Correspondingly, a comparison of earlier studies indicates that there were relatively few differences between platforms in terms of topic and style (16,30,31,60,66,96,121), and outlets made little use of platform features such as videos or hashtags (33,55,97).In turn, many recent studies conclude that outlets adapt their content to each platform (e.g., 18, 19, 26, 56, 62, 69, 82, 143).As they respond to shifting algorithm preferences (140), even newspapers-organizations without a legacy in video production-increasingly value videos (e.g., 36, 42, 64, 94, 117, 149).Some ambivalences remain, however.For instance, while some outlets differentiated between the more social platform Facebook and the more news-oriented Twitter early on (e.g., 30, 82), others did not develop distinct strategies.Some recent studies also indicate that outlets select SMP content "totally gaga" (Hågvar 2019, 860; see also 6) or opt for hard news content across platforms (10,20,62,151).These ambivalences suggest the influence of factors such as intra-organizational processes, as stressed in the discussion.

Discussion
Responding to the growing importance of SMP for news users and organizations alike, there is a plethora of research investigating which content news outlets produce for SMP and why.This SLR set out to synthesize scholarly knowledge about how news organizations coordinate, select, and edit content for SMP.This last section discusses the main findings, identifies research gaps, and proposes paths for future research.

Conclusion 1: A Broad Research Field-Potential for Depth
RQ1 aimed to identify the prevalent research contexts, theories, and methods of publications that explore news organizations' SMP content production.Overall, the SLR identified a fairly diverse research field whose growth is in accordance with the increasing importance of SMP for news (use).The 156 included publications were conducted in many different contexts.For example, scholars paid considerable attention not only to Twitter but also to Instagram and TikTok.Likewise, the studies were often comparative and conducted in different geographical contexts.Finally, they investigated SMP content production in a variety of topics and applied a diverse set of theories.Notwithstanding the creditable breadth of this research field, the SLR identified areas where it could be enriched by greater depth.
First, there appears to be a lack of social media-specific theory perspectives.This conclusion may seem counterintuitive, as social media logic is not only the most prevalent theory when looking at shares of single theories but, as seen in the review at hand, also delivers evidence that it does matter (see Conclusion 2).However, this concept tends to focus on the common ground of all platforms (van Dijck and Poell 2014, 5).Additionally, most scholars apply a non-SMP-specific theory-framing and value theory are especially prevalent-and hardly theorize on the impacts of specific platform characteristics on content production.Accordingly, SMP are treated as a monolithic bloc without theorizing on the characteristics that cause (expected) outcomes in terms of journalistic content.This generalization may be problematic: research in the context of SMP is confronted with the "moving target" problem (Valkenburg, Peter, and Walther 2016).Some platforms become outdated, others become more attractive, and still others are not yet known at all.Therefore, scholars require better knowledge about (the combination of) single characteristics that shape journalistic production decisions.
Second, only a minority of studies provide insights into actual content production processes.Most authors conduct quantitative content analyses and primarily address the selecting or editing programs, while the coordinating program is less prominent.Likewise, ethnographic studies are widely missing, though they would be able to provide researchers with nuanced evidence about production processes.Consequently, there is considerable evidence on what outlets post on SMP; evidence on why, however, is often only inferred from content analyses and thus remains somewhat speculative.This may contribute to the ambivalences between outlets that this SLR identified.
The following discussion points offer concrete ideas on how the research field could be advanced in its respective directions.

Conclusion 2: No General Trend of News Softening
RQ2 asked about the current knowledge of how news organizations coordinate, select, and edit content for SMP.Generally, many news organizations reacted to the growing importance of SMP by hiring SME.However, their organizational embeddedness differs: Especially in legacy organizations, they are often only responsible for publishing the content.In other organizations-often digital or SMP natives-SME play a more central role in the newsroom and are involved in the whole production process.
With regard to selecting and editing, one of the most interesting findings from this SLR is that journalistic content for SMP is not generally softened, that is, not onesidedly centered on light issues and delivered in an emotionalized, personal manner.Instead, many studies across different contexts inform of a considerable share of featured hard news topics like politics and current affairs, as well as a tone that is often informative and neutral.One important reason for this caution relates back to image conservation.To preserve their brand's reputation, especially the SME of quality legacy outlets "cannot just post viral content" (Lischka 2021, 21).Instead, they have to save it for "specific occasions" (Denisova 2022, 7; see also Ashuri and Frenkel 2017;Walters 2022).
Importantly, this is not to argue that news outlets ignore social media logic.Rather, in line with an earlier review on online journalism (Mitchelstein and Boczkowski 2009), this SLR shows that there is both a persistence of traditional routines and structures and an invention of new ones.News outlets do not simply adapt to SMP; instead, over time they find balancing strategies through which they can "appropriate" SMP in a way that guarantees the persistence of their professional values (MacGregor 2007;Singer 2005).Specifically, news outlets "marry" mass and social media logic (Lischka 2021).
For instance, journalists reserve emotional and colloquial language for lighter topics (e.g., Groot Kormelink and Costera Meijer 2014; Hågvar 2019), while coverage about the coronavirus was often neutral and focused on politics instead of affected individuals (e.g., Laferrara and Justel-Vázquez 2021;Masullo, Jennings, and Stroud 2022;Quandt et al. 2021).Outlets also experiment with the softening of hard news: by using a colloquial tone or enriching their content with visual features such as emojis, they try to edit news about current affairs to be as appealing and entertaining as possible to find success within algorithmic and social curation contexts (e.g., Denisova 2022;Sormanen, Reinikainen, and Wilska 2022;Vázquez-Herrero, Negreira-Rey, and López-García 2022).Thus, fears of losing journalistic quality in the SMP context, as mentioned at the beginning of this article, can at least be mitigated.In contrast, these findings also contain an optimistic notion: journalisms' platformization implies that outlets can provide content that both resonates with SMP core audiences and is informative and relevant.In this sense, the idea outlined by Hendrickx (2021) that news outlets should further experiment with unpacking difficult content in an appealing way already seems present, even in some legacy newsrooms.

Conclusion 3: Platform Characteristics Matter
The SLR identified patterns of SMP influence on production decisions that deserve further investigation.Generally, orientation toward algorithmic curation was influential across studies.News outlets are well aware that they are dependent on algorithmic preference.Interestingly, though, several studies note that SME consider algorithms too complex and dynamic to adapt content accordingly (Lischka 2021;Neilson and Gibson 2022;Peterson-Salahuddin 2021).Instead, they take the preferences of the (imagined) audience (i.e., the users who partly shape the algorithm) as a guiding principle.Where algorithms alter erratically, user preferences can be discovered by analyzing metrics or asking the community for feedback.
Next to the relevance of algorithmic selection, this SLR also found evidence for more nuanced platform differences.For example, certain studies show how the mere existence of a link feature shapes content production or how outlets adapt to the "language" and formats of a specific platform.These single pieces of evidence of the influence of different SMP characteristics can be considered an impulse to gain a more nuanced understanding of how platform characteristics shape journalistic content.
Theoretically, as mentioned in Conclusion 1, it could be fruitful to employ approaches that are more open toward specific SMP characteristics than social media logic.An example are "social media architectures" that describe the technological features and functionalities of platforms, such as their different post formats and engagement cues (Bossetta 2018).Another promising approach involves the dimensions of social media logic as proposed by Hermida and Mellado (2020): instead of focusing on a logic common to all SMP, this framework searches for the differences regarding the genres and languages of SMP.
Methodologically, future research could focus on methods that provide "thick" data, which is often small in sample size but denser, more detailed, and more context-sensitive (Latzko-Toth, Bonneau, and Millette 2017, 201).For example, scholars might employ innovative methodological approaches such as "post-selection" walkthroughs (lending from the Post-Exposure-Walkthrough; see Kümpel 2019;Zerfass and Hartmann 2005).Journalists or SME could be asked to navigate SMP while thinking aloud about the relevant functions and characteristics of the platform.These walkthroughs could then be enriched with "reconstruction interviews" (Reich and Barnoy 2016).Confronted with the SMP content they produced accordingly, SME could then describe its production and reflect how it was influenced by platform characteristics identified during the walkthrough.

Conclusion 4: The Organization Matters
Throughout the analysis, differences between outlets emerged.First, private sector media investigated by the sampled studies seem to orient their content more toward SMP.This observation might be explained by these media's dependency on revenue from SMP traffic (R. K. Nielsen 2019, 333;Sehl, Cornia, and Nielsen 2021, 5).Second, brand identity matters: Scholars often found that public broadcasters and broadsheets are concerned with preserving their reputation and therefore were hesitant with overly popularizing content.In turn, tabloid organizations may consider entertaining content as their "natural habitat" and therefore focus more on light topics and emotional editing (Hågvar 2019, 869;Larsson 2018, 55).However, these overarching patterns do not remain without contradiction.One explanation might be the intentions of individual actors or intra-organizational processes that the SLR could hardly address: due to the design of the sampled studies, organizations and outlets mostly remained a "black box."Nonetheless, especially the included interview studies hint at several factors that deserve further investigation.
On the individual level, a few studies indicate that the professional background of SME is important.For instance, one study shows that SME with a marketing background are more unambiguously oriented toward engagement and content popularity (140).Meanwhile, studies that reveal conflicts between professional standards and social media characteristics tend to have interviewees with a journalistic background (e.g., 78,121,132,145).Thus, interview studies systematically comparing the role orientations and work practices of SME with different professional backgrounds offer a promising path for future research.
On the organizational level, the SLR highlighted the relevance of SME's organizational embeddedness and their status within the newsroom: the more SME are integrated in the whole production process and/or work closely with the marketing department (99), the more platform-tailored the content appears (41,123).Departing from this finding, it seems fruitful to delve deeper into SMP-associated routines and practices within different outlets.For example, future studies could more thoroughly examine potential conflicts between legacy journalists, management personnel, and SME that might arise because of diverging experiences and professional backgrounds.In this regard, scholars could explore the existence and role of SMP-enthusiastic "early adopters" and skeptical "laggards" (Rogers 2003) within the newsroom.Moreover, thus far widely missing insights about procedures, roles, and authority at newsroom meetings could provide a deeper understanding of SMP content production.
Finally, the SLR's results call for further investigation of country-level differences.Although studies comparing topics across countries show a similar pattern of political news orientation (3, 10, 28), the picture is more nuanced of whether the content is opinionated.Here, it seems that outlets from southern media systems editorialize more often (e.g., 7, 47, 156) than those from northern or central ones (e.g., 89, 106, 125).This finding is consistent with southern media systems' higher levels of political parallelism (i.e., whether political advocacy is perceived as a legitimate part of journalism) and lower levels of professionalization that favor instrumentality, which could lead to more subjective content (Brüggemann et al. 2014(Brüggemann et al. , 1040)).However, there are only two comparative studies showing this pattern (22,47).Future studies could build on this evidence by engaging in systematic comparisons of the SMP content (production) of outlets situated in different countries.

Limitations and Outlook
This review's approach comes with some limitations.First, although the broad approach of the analysis allowed for a comprehensive overview of the research field, the resulting heterogeneity of concepts, methods, and measures renders comparisons and a more standardized analysis difficult.Second, regarding the search procedure, while the chosen set of keywords distinctively included synonyms, it is possible that articles were omitted that did not match with the predefined set of keywords but would have nevertheless been relevant to the literature review.Moreover, the SLR sample excluded unpublished articles, dissertations, and monographs, as well as it focused on English-language publications.Third, both the sampling and analysis were conducted by only one researcher.As a consequence, the intercoder reliability of the instruments used for sampling and analysis cannot be calculated, meaning it is not possible to control for coder effects (e.g., learning effects) and potential biases that might have influenced the results.Fourth, the scope of the review is limited: news outlets are only one actor in the "triple-party news-spaces" (Tenenboim 2022) that SMP constitute.Simply because they produce more or less democratically valuable material does not imply that audiences are reached.Especially on SMP, content is often discovered incidentally and curated by both algorithms and social contacts (Kümpel 2022;Thorson and Wells 2016).
However, for the journalistic party, this SLR makes two major contributions.First, it describes the diverse research on news organizations' production of content for SMP such as Facebook, Twitter, and Instagram, allowing the identification of methodological and theoretical gaps in the field, and proposes paths for future research.Second, it shows that although SMP content production differs between platforms and organizations, there is a common ground: it remains a constant negotiation of platform characteristics and professional standards.

Figure 1 .
Figure 1.Development of data collection and publication activity over time.Note: As sampling was conducted in January 2022, the data capture only a small part of the research activity in 2021 and 2022.

Table 1 .
Most prevalent contexts, theories, and methods in the sampled publications.