In past decades, science videos reaching large audiences were usually from professional science communicators or organizations. Online video has changed this, blurring the line between professional and amateur producers (Morcillo et al., 2016). Although many online science videos come from media companies, they may also come from scientists, science educators, engineers, and interest groups, to name a few (Welbourne and Grant, 2016; Rosenthal, 2018), and there is evidence that audiences like science videos more when they come from scientists vs. non-scientists (Sugimoto and Thelwall, 2013). Despite the diversity of science video producers, minorities are underrepresented in their ranks (Campbell et al., 2019).

Video producers use many techniques and genres to communicate about science (Morcillo et al., 2016). Online science videos often have an informational purpose but also frequently aim to raise awareness or entertain (De Lara et al., 2017). Videos targeting awareness present information about an issue to enhance its salience or perceived importance. The information contained in online science videos can be scientific, pseudoscientific, or non-scientific and can move audiences toward or away from mainstream scientific views (Erviti et al., 2018; Landrum and Olshansky, 2020).

Video can be an effective tool for communicating about scientific issues (Ferraro et al., 2019) and there is an ongoing need to understand channel effects (Jeffres, 2015). The channel of online video has many distribution platforms. Among those channels, YouTube seems the most popular for individuals seeking science-related information (Metag, 2020), but users can also find and share videos on social media, such as Facebook, and social messaging platforms, such as WhatsApp.

Extensions of the SMCR model often include feedback involving the two-way flow of information (Narula, 2006). In the past, video broadcast allowed limited feedback (e.g., writing letters) from large and diffuse audiences (Beyer et al., 2007). Video sharing platforms have changed that dynamic, creating channel affordances for audiences to share ideas more directly with content producers (Erviti and Stengler, 2016). Live video streaming creates additional feedback mechanisms, where producers can interact in real-time with their audiences (Wang and Li, 2020).

The different online video platforms have potentially large audiences. YouTube alone has more than two billion users (YouTube, 2020). Although there is evidence most of those users do not regularly watch science videos (Tsai et al., 2016; Rosenthal, 2018), it is likely most will encounter such videos—including those spreading misinformation—at some point. Several factors affect motivation to seek science videos on YouTube, including perceived social norms, enjoyment of science, and an information orientation to YouTube (Rosenthal, 2018). The effects of science videos on audiences include more participation in scientific discourse (Shapiro and Park, 2015) and more positive perceptions of scientists (Brewer and Ley, 2017).

Another extension of the SMCR model involves noise, which refers to distortions or errors interfering with message transmission (Narula, 2006; Shrivastava, 2012). For example, low internet bandwidth can lead to video pixilation, reducing the image quality. That is one kind of channel noise because it arises due to features of the communication channel. There are two additional kinds of noise relevant to this article. First, the diversity and bulk of science video content can cause information overload, which is a source of noise (Ruff, 2002). Second, individuals with low media literacy may have difficult navigating content and those with low scientific literacy may have difficulty interpreting the meaning of messages, which can create semantic noise (Shrivastava, 2012). The next section discusses media literacy and scientific literacy and how they may influence audience reception and responses to science videos on the internet.

Much like with the general concept of literacy, scholarly definitions of media literacy have evolved over time (Cappello, 2017). Whereas, an early definition focused on the ability to consume and create media, a more recent definition considers it as a framework of participation, which involves consumption and creation, but also “builds an understanding of the role of media in society as well as essential skills of inquiry and self-expression necessary for citizens of a democracy” (Thoman and Jolls, 2008, p. 42).

This kind of literacy may also serve a protective function in a media landscape containing information-related risks. Individuals with high media literacy can better protect their privacy, avoid cybercrimes, and reject fake news and other misinformation (Lee, 2018). In the context of science communication, misinformation is doubtless a problem. There is evidence that structural changes, such as issuing corrective information, can be an effective way of combatting scientific misinformation (Bode and Vraga, 2015), but there is an accompanying need to enhance public media literacy and encourage more open dialogue about contentious issues (Scheufele and Krause, 2019; Vraga and Tully, 2019). In the context of health information, a kind of scientific information, Madathil et al. (2015) called for media literacy education to help individuals make more informed health decisions. Being able to sift through multiple and sometimes conflicting messages requires cautious and critical media use [see also, Cooper (2011)].

Naturally, the importance of media literacy extends to video sharing sites, where the sheer volume of video content necessitates a critical or at least cautious approach by audiences. Meyers (2012) emphasized this importance when young people engage with informational videos on YouTube. Because online video sharing allows virtually anybody to create video content, audiences need to rely more on themselves to evaluate authority and credibility. He argued, not only do individuals need to be able to critically assess the qualities of sources and messages, but they also need to have appropriate responses when it comes to sharing information and participating in discourse. Part of this process involves the evaluation of scientific claims, which implicates scientific literacy.

There are many overlapping conceptualizations of scientific literacy (Laugksch, 2000; Jarman and McClune, 2007). According to a popular and parsimonious definition, scientific literacy involves “understanding of scientific terminology and concepts; scientific enquiry and practice; and the interactions of science, technology, and society” (Jarman and McClune, 2007, p. 3). In short, it entails knowing about scientific facts, the process of discovering those facts, and how people collectively use that knowledge. Measures of scientific literacy have commonly gauged factual and process knowledge (National Academies, 2016). Scholars have drawn on such operationalizations to examine public understanding of scientific sub-domains, such as climate change (Kahlor and Rosenthal, 2009; Kahan et al., 2012), indoor air quality (Rosenthal, 2011), and nanotechnology (Drummond and Fischhoff, 2017). There have also been efforts to disambiguate religious beliefs from scientific understanding because, for example, someone who does not believe in human evolution may still have good knowledge of what the theory describes (Roos, 2012; Kahan, 2017).

Scientific literacy can benefit people at the micro- and macro-level (Laugksch, 2000; Yacoubian, 2018). At the micro-level, scientifically literate individuals have the skills and confidence to make science-related decisions, which often involves interpreting scientific information in the media (e.g., Nisbet et al., 2015; Nordheim et al., 2019). At the macro-level, a scientifically literate society can provide the supply of individuals with skills needed for scientific advancement. Further, a scientifically literate public may be more supportive of science and, importantly, engaged with democratic decision-making about science-based issues (Yacoubian, 2018).

Emphasizing the macro-level perspective, Roth and Lee (2002) argued scientific literacy is less about the minds of individuals and more about collective activities; it is not a property of individuals but an achievement of society. In conclusion, they called for more work documenting “conversational spaces that enable scientific literacy to emerge and permit life-long learning” in informal or other non-traditional learning venues (p. 53). Science videos on the internet often provide that space and are beneficial in that regard. The next section focuses on this and other benefits before turning to some of the drawbacks of science videos on the internet.

There are many potential benefits of science videos on the internet. This section reviews three benefits, beginning with a discussion of video as a learning tool. Ferraro et al. (2019) argued that the auditory and visual experience of videos is a powerful tool for science education and engagement. The structure and organization of video content may serve as a guide for audience's attention and knowledge construction (Merkt et al., 2018), especially when there are interactive features, such as clickable elements (Tsai et al., 2016; Palaigeorgiou et al., 2019). Carefully selected online videos may be an effective complement to classroom science education by supporting independent learning (Pecay, 2017) and allowing learners to take new perspectives (Higgins et al., 2018). This benefit is pronounced among youths (Moll and Nielsen, 2017; Dunlop et al., 2020), whose orientations to some topics affect their reactions, like engaging in serious discourse (Meyers, 2012). Outside formal learning venues, both students and members of the public may use online videos to learn about many topics, including science (Moghavvemi et al., 2018; Rosenthal, 2018).

Part of how online science videos support learning is through the co-construction of knowledge by audience members. Dubovi and Tabak (2020) studied YouTube user comments about science videos, finding disagreements led to “rise-above collaborative elaboration,” in which commenters provided evidence to support their claims. In a similar study of YouTube videos about antimicrobial resistance, Djerf-Pierre et al. (2019) found users were engaged with the issue and their comments expressed emotion, assigned blame, and called for action. These studies show a second potential benefit of science videos to encourage scientific discourse in public. This benefit is largely a function of online video supporting not only feedback from audiences, but engagement among audience members (Ksiazek et al., 2014). Further, Morcillo et al. (2018) discussed how producers engage in community building, which they do to ensure their own success, but which also creates a sense of connection with their audiences. Erviti and Stengler (2016) reported similar instances of community building by video producers. In other words, discourse as co-construction of knowledge may involve not only exchanges between audience members but also with content producers.

Despite some unique affordances of online video to facilitate discourse about science, audiences are unlikely to become engaged with the content if the scientific issues are not important to them. Scholars have talked about this personal importance in terms of issue involvement, which is positively related message processing (Petty and Cacioppo, 1979, 1986). Kahlor et al. (2006) used this idea to predict the seeking and processing of environmental risk information, another kind of scientific information. Given the sheer volume and variety of online science videos, it is likely most people can find personally involving content. This can create new points of public engagement with science. Although research has not shown this in a science communication context, Cha (2014) argued content variety is an advantage of video sharing sites and found it is positively associated with video consumption. However, as the next section suggests, content variety is a double-edged sword.

Whereas content variety may create many points of public engagement with science, it can also lead to information overload and selective exposure (Takahashi and Tandoc, 2015; Lee et al., 2017). Karlsen et al. (2017) expressed concern over the sheer quantity of health information online and difficulty for some individuals in finding credible health-related videos on YouTube. They suggested unfamiliarity with new media technology and low health knowledge exacerbate this difficulty, which has clear implications for media literacy and scientific literacy. There is additional difficulty related to source selection. Erviti et al. (2020) found messages opposing science are more likely to appear in user-generated content than in content from media companies.

Another reason content variety is a double-edged sword is because some producers create content to lead viewers away from scientific consensus (Erviti et al., 2018; Allgaier, 2019), creating a polarizing conduit of pseudoscience and misinformation (Bessi et al., 2016). Highly polarizing videos tend to garner more audience engagement in terms of likes or comments (Briones et al., 2012; Heydari et al., 2019). This can produce epistemic bubbles and echo chambers, where groups of likeminded individuals become entrenched in their viewpoints through patterns of media use (Nguyen, 2020). One explanation of this social and psychological entrenchment is confirmation bias, or the tendency of individuals to focus on information supporting their existing beliefs (Ling, 2020). This tendency is more likely among individuals who believe their current knowledge about an issue is sufficient (Jang, 2014). Of course, people who know the least about an issue tend to overestimate their knowledge the most (Kruger and Dunning, 1999), and echo chambers may amplify this effect in the context of scientific issues (Bentley et al., 2019).

Although selective exposure and echo chambers are not new phenomena, there may be more opportunities for them to manifest in a new media landscape. This is partly because anyone can create media content and have direct access to potentially large audiences. As a result, the role of information gatekeeper has shifted away from media professionals and toward a more diffuse group of actors who guide information to smaller audiences (Lewis, 2020). On the one hand, this more specialized gatekeeping can be beneficial because it personalizes the information audiences receive, possibly leading to more issue involvement and engagement. On the other hand, there is less clear separation between facts and opinions, especially on scientific topics (Brossard, 2013). When opinion appears as scientific fact, more engagement probably leads away from constructive discourse.