Abstract
Introduction
The recommender systems that drive platform features like TikTok's ‘For You Page’, YouTube's ‘up next’ feature, and Spotify's ‘Discover Weekly’ playlists have become central to ordering content, driving user engagement, and maximising advertising value for digital media and entertainment platforms. They are multi-stakeholder systems that mediate multi-sided markets, appealing simultaneously to the end users receiving recommendations, the content creators or media producers reliant on algorithmic distribution, and the advertisers seeking to reach relevant audiences.
In recommending content to users, global platforms must also navigate the national and international laws and business rules that impact what content is available to which audiences. These include market segmentation wrought by copyright licensing, local content requirements in those jurisdictions that have extended this regulation to subscription video on demand services (SVODs), for example, and content restrictions imposed through classification-style regimes, morality laws, or ‘brand safety’, which can impact materially on the careers of online creators. And, in an environment of increasing public concern about the impact of ‘algorithms’ on society, platform companies also have an interest in convincing regulators, advertisers and other third parties that they are curating content or items responsibly (Helberger et al., 2018).
The idea of diversity shows up in relation to all these entangled and competing interests – interests which recommender systems need to negotiate and balance. In this short article, we sketch some of the competing meanings attached to ‘diversity’ in the context of various media and cultural platforms’ recommender systems and by a range of humanities, social science and technical disciplines, and suggest some of the areas where these different meanings offer potential for collaboration in the public interest.
Diversity in recommender system design
Recommender systems are ‘prediction machines’ (Agrawal et al., 2018): they use data and machine learning to suggest content the system bets users will engage with. Platforms present these suggestions to users via features such as newsfeeds, custom playlists, and personalised landing pages. To make their predictions, recommender systems generally combine two basic principles: ‘collaborative filtering’ and ‘content-based’ recommendation.
Collaborative filtering draws on patterns of user practices across a section of the platform's population. To take music streaming as an example, suppose Spotify users who frequently listen to Lady Gaga also tend to listen to Beyoncé. In that case, it makes sense to recommend Beyoncé to those Lady Gaga fans who have not yet discovered Beyoncé. ‘Content-based’ recommendation is based on an individual listener's engagement with diverse types of musical content: if a user frequently listened to 1960s jazz during the past week, it is reasonable to recommend more jazz from the 1960s to this user during the week ahead.
Traditionally, when recommender system designers evaluate the effectiveness of a recommender system, they focus on the
Within the branch of computer science scholarship that underpins recommender system design and evaluation, diversity is simply a measure of the number of distinct items (songs, videos, news articles) that appear in a list of recommendations (Kunaver and Požrl, 2017). However, the differences or similarities among these items can be measured using a number of
On music streaming platforms, for example, diversity can be measured through collaborative filtering that computes recommendations based on user data input; content-based approaches that index musical metadata and annotation added by humans; and contextual approaches, such as environmental factors (time of day, weather, holiday events); or psychological factors (personality, mood, social setting) (Schedl et al., 2015). Even more possibilities exist when computationally analysing musical audio files, including features such as those Spotify labels as ‘danceability’, ‘acousticness’, ‘energy’, ‘instrumentalness’, ‘liveness,’ ‘loudness’, ‘speechiness’, ‘tempo’, and ‘valence’ (Spotify, n.d.). We would argue such measures could be reconnected to cultural concepts relating to aesthetics, genres, and subcultures, suggesting creative possibilities for collaboration with computer scientists.
There is plenty to build on: cultural sociologists have a long tradition of studying different aspects of diversity in cultural fields such as popular music for reasons concerning questions of taste and artist welfare, and their approaches could be adapted for use in the contemporary era. Starting in the 1970s, sociologists (e.g. Lopes, 1992; Peterson and Berger, 1971) examined how aggregate consumption diversity, operationalised as the number of unique songs that reached a certain level of popularity, evolved over time. Other studies focused on content diversity in terms of genre or acoustics (e.g. Bourreau et al., 2022). Meanwhile, some economists (e.g. Aguiar and Waldfogel, 2021) addressed geographic aspects of diversity, such as the distribution of commercially successful artists across countries. The questions driving these studies were primarily focused on how diversity was impacted by factors such as industry concentration (Peterson and Berger, 1971) or digitisation (Bourreau et al., 2022) and explain why diversity fluctuated over time.
While we have so far mainly discussed music systems, there is much experimentation and variety across other kinds of recommender systems, for various media forms, further complicating the challenge of defining and evaluating diversity (Morales et al., 2021).
Representational dimensions of diversity
In addition to medium-specificity, a cultural studies approach to analysing and improving diversity in recommender systems would incorporate moral questions such as fairness, justice, and equality. Dimensions of recommendation addressing these questions might include the number and prominence of content creators (musicians, authors, or YouTube creators) representing a range of identity backgrounds; the amount and prominence of content representing a range of viewpoints or perspectives; or approaches designed to surface ‘niche’ or ‘long tail’ content, satisfying users with less mainstream preferences and avoiding popularity bias. Some advances in this respect have been made in work focused on news (Hilden, 2022); scholars and policy-makers are testing long-standing questions of media diversity (Napoli, 1999) against the operations of public service media (PSM) systems, and using their findings as the basis of policy and technical innovations (Helberger, 2018).
Scholarship on social media entertainment and the creator economy also highlights issues of inequity and bias in recommender systems tied to visibility of particular social identities and bodies (see Duffy and Meisner, 2023; Gillespie, 2022; Nicholas, 2022). Content featuring women of colour, trans people, people with disability, and plus-sized bodies are among the types of content that creators report being less likely to benefit from – or even to be suppressed by – algorithmic recommendation (Middlebrook, 2020), although platforms make it remarkably difficult for creators to prove these claims (Cotter, 2021).
Beyond concerns about unequally distributed attention, there are also issues of harmful representation, stereotyping and the commodification of diverse identity groups through recommendation. Noble's (2018) work was pioneering in this respect, finding that commercial search engines returned results that reinforced the historic sexualisation and dehumanisation of Black girls. Gerrard and Thornham's (2020) analysis of Pinterest's recommender system revealed the ways it connects content about eating disorders with ideals of ‘consumerist, youthful and white’ femininity, arguing that ‘what gets generated through recommendation systems are over-simplified versions of gender and other identities’ (2020: 1279) that tie in with the commercial objectives of platforms and advertisers.
Geographic dimensions of diversity
Geographic dimensions of diversity are important to consider in the context of global digital platforms (Steinberg and Li, 2017). To take the example of streaming video on demand (SVOD) platforms, whose politics link to long-standing debates about media globalisation and related policy concerns, part of the strategic advantage of platforms like Netflix is their ability to ‘imagine [and algorithmically target] their subscribers as
In reality, global platforms remain locally situated, albeit in uneven ways. They must negotiate (or bend to) state power in a variety of jurisdictions to meet commercial objectives (Khalil and Zayani, 2021); they invest more heavily in local content in some countries than others (Lobato and Lotz, 2021); and consumers face regional restrictions in content availability (Elkins, 2019). Long-standing concerns about the consolidation of power imbalances between countries and the risk of cultural imperialism have taken on renewed urgency (Lotz et al., 2022) in this context. Netflix continues to contend with, and claims to continue to try to optimise its recommender systems for, more localised country and regional preferences: including preferences related to language (Raimond and Basilico, 2016) – a key dimension of diversity.
In Australia, long-standing broadcast television legislation (Australian Parliament, 1999) dictates that 55% of programs broadcast on primary channels each year between 6 a.m. and 12 a.m. must be ‘Australian content’. When Netflix entered the Australian market in 2015, it was not constrained by this legislation, and was therefore able to attract large numbers of Australian subscribers through its premium offerings of US television (Lobato, 2019; Turner, 2018). Nevertheless, Australian viewers are accustomed to seeing high levels of Australian television (Deloitte, 2020), and to viewing diversity through an Australian lens (Khoo, 2022), creating demand for local content and complexity for recommender systems. For example, many Australians would expect that ‘Black’ programming will include representations of ‘Blak’ Australians – Aboriginal and Torres Strait Islander people (Turner, 2020).
It is important to note that identity-based diversity can operate in tension with nation-based customisation (or ‘localisation’). Global platforms are important sites for queer affiliation and belonging
Conclusion
The role of recommender systems in mediating diversity on behalf of global platforms is complex, fraught, and deeply consequential for content producers and creators, as well as for their publics: but the very fact that diversity has so many meanings and values attached to it make it a productive site for intervention. TikTok's public-facing recommendation guidelines 1 are instructive in this regard. At first glance, they suggest the company conceptualises ‘diversity’ in a narrow, easily operationalisable sense (recommending content by different creators or about different themes) because ‘[o]ur community tells us they love finding creators they wouldn’t have known to follow, or learning about a new interest because it was recommended to them, along with enjoying content that already matches their taste’. But the platform also makes a subtle appeal to rationales for diversity beyond user experience, stating that its ‘systems won’t recommend two videos in a row made by the same creator or with the same sound’, not only because ‘[d]oing so enriches the viewing experience’ but also because it ‘can help promote exposure to a range of ideas and perspectives on our platform’. The platform also positions recommendation ‘diversity’ as part of its approach to ensuring user safety: claiming to diversify the viewing experience of users away from content that ‘though not violative of our policies, could have a negative effect if that's the majority of what someone watches, such as content about loneliness or weight loss’. In that sense, ‘diversity’ is presented not just a way of engaging users, it is also an element of ‘responsible’ curation. Amid widespread concerns about recommender systems’ tendency to reinforce existing views and relationships rather than expose users to new ones (creating ‘filter bubbles’), and in the amplification of harmful ideas and modes of expression, TikTok promises to expose viewers to ‘a range of ideas and perspectives’ and shield them from content that may be ‘problematic if viewed in clusters’.
Diversity, then, is a heavily freighted keyword (Williams, 1977; see also Peters, 2016) in the global digital media environment: it is a multivalent concept that wields operative power in a variety of ways over the external policy environments, internal rules, content, and technical elements of platforms, with significant implications for the careers of cultural producers and experiences of audiences. Following Williams, we choose to see this play of meanings not only as a symptom of political struggle, but as a resource of hope, however modest, for productive interventions.
Recent advances in the field of recommender design, in combination with a range of pressures on platforms to improve the amount and quality of diversity in their recommendations, offer nascent possibilities. As the brief survey above suggests, the dimensions of diversity already used by recommender systems in cultural and entertainment platforms range across a matrix that mixes cultural, business and governance considerations: in many jurisdictions they need to balance the local, national, and global; in order to be effective in their own terms they need to ensure aesthetic and content diversity; and for both practical and ethical reasons, representative social and identity diversity may be part of the picture. To fully engage with these competing practical and normative questions is going to be challenging but increasingly necessary for global platforms. To do so would involve experimenting with multidimensional models of diversity in collaboration with diverse creator and user communities, and in dialogue with civil society.
