Tag: social-media

Does TikTok influence our viewing habits?

After six months of work on this project, I finally have my first set of data. In this post, I want to reflect on what these data might tell us about people’s relationship with TikTok—and what they reveal about how we study the perception of this platform. It’s not just about what the data show, but also how we interpret them and what questions we should be asking next.

In my initial experiment, I collected valid data from 28 participants. Each participant watched the same set of videos on a computer with eye-tracker, presented in two formats: landscape and portrait. Before every session I made a note of participants’ screen time (TikTok, Instagram, and YouTube) – not through self-reporting, but by directly checking the screen time data on their phones.

After processing and analysing the data, we obtained interesting information about differences in fixation entropy, saccade directions, and, in general, the relationship between video format and stylistic elements in the context of perception. We are preparing academic outputs on all of this. But what surprised me the most was something else.

We were unable to measure any convincing effect of screen time on the way videos are watched. It even makes me rethink some of my hypotheses. But let’s take it step by step.

To be honest, I did find one statistically significant correlation. And it’s one that deserves a headline in the newspapers: TikTok makes you less focused when watching movies!

Sounds serious, right?

More precisely, we found that participants with higher average screen time on TikTok have a greater distance between fixations when watching landscape videos. In other words, if you watch a lot of TikTok and then watch a movie, your eyes will jump around more than the eyes of people who don’t watch TikTok.

Does it still sound serious?

Take a look at the graph illustrating this effect. The p-value even shows that the effect is statistically significant.

Does it sound even more serious now?

Notice the dots on the y-axis that have zero screen time on TikTok. Let’s try visualizing the data differently to get two groups: TikTok users and non-users.

And suddenly, the effect is gone. Or at least it is so small and statistically insignificant that nothing can be said with certainty on its basis.

What happened?

Imagine that you collect a huge amount of data (fixations, saccades, pupil diameters, blinking… in the spreadsheet with more than 100 columns and calculate metrics such as entropy, dispersion…) and add to it other data from a questionnaire (age, gender, average screen time…). Then you just try to look for what correlates with what until you find that some correlation is statistically significant. In other words, you are committing fraud by randomly comparing data and looking for something that looks like positive result. And when you get a low p-value, only then do you formulate a hypothesis. This is called data fishing or p-hacking.

I was in the opposite situation. I measured the effect predicted by the hypothesis. The problem was that when I then explored other variants of correlations between screen time and eye-tracker data, I didn’t find any other statistically significant correlations. The one with screen time on TikTok and fixation distance in landscape videos was the only one. Sometimes it even showed me that higher screen time correlates with more focused fixations. The complete opposite.

These findings have led me to reconsider some of my initial assumptions. I originally believed that long-term exposure to TikTok would affect the way we watch films. But based on the current data, that effect is either not present or not captured by my experimental design. In any case, I don’t have sufficient evidence to claim that screen time directly influences how we watch videos. What’s more, I began to doubt whether it still makes sense to continue focusing on studying influence of screen time on viewing habits.

Another important takeaway concerns how we interpret claims about TikTok’s influence on cognition. Keeping in mind what Stuart Ritchie wrote in his excellent book Science Fictions, I’ve begun to question the many articles that describe TikTok as fundamentally reshaping our brains and behavior. Perhaps those effects are real—but we should be cautious when such strong claims are supported by just a single metric from an eye tracker or similarly narrow data sources.

Finally, these results also shape how I’ll present my own research moving forward. I’ll keep the question in the title of this post, because it’s accessible and engaging. But in answering it, I’ll emphasise a crucial distinction between a) TikTok as an app, b) the formal elements typical of TikTok videos, and c) the vertical video format itself. Unlike screen time, both the formal elements and the vertical format show clear evidence of influencing how we watch
videos.

July 15, 2025

data, research, screen time, social-media, technology, tiktok
Is TikTok really as fast as we think?
I often encounter the opinion that TikTok is fast. Frankly, I’ve never understood it. I could describe TikTok in a number of words, but speed would not be one of them. Maybe the problem is what we mean by speed.

The last time I came across the idea was in Berenike Jung’s “Travelling Sounds, Embodied Responses: Aesthetic Reflections on TikTok” from the anthology Traveling Music Videos edited by my colleague Tomáš Jirsa. Berenike Jung describes TikTok as follows:

“the videos’ short length creates an accelerated, hypnotic pace of viewing. The videos are themselves often accelerated and/or stuttering, edited to a speed that puts chaos cinema in the rearview mirror and further normalizes jump cuts as the rule for online videos”

I identify speed in three senses in the quote:
1. the fast pace caused by the short length of the videos
2. the acceleration of videos
3. the use of jump-cuts to eliminate shots where nothing important is happening
In at least two of these, it is something we have known for decades, so it hardly surprises any viewers today. Anyone who has ever watched a silent movie has encountered video acceleration (the reason for this is the different standard of projection speed expressed in terms of the number of frames of film stock per second of projection).

Similarly, the jump-cut cannot be considered anything groundbreaking. It is associated in film history books with Godard’s A bout de souffle (1960), but even that was not the first use. David Bordwell wrote an article on the jump-cut in 1984 (Wide Angle, vol. 6, no. 1) where he points out that the jump-cut had been used since the early era. In my notes, I found uses of the jump-cut in, for example, the Finnish film Valkoinen peura (1952, Erik Blomberg).

The remarkable speed of TikTok can therefore perhaps only be explained by the short length of the videos. And while we could find examples from the past (commercial breaks on TV, blocks of trailers and ads in cinemas before the screening starts, blocks of video clips on TV and YouTube), TikTok has at least contributed to shortening videos to a new level.

But the list of possible understandings of what makes TiKTok fast is not, in my opinion, complete. Leaving aside the contextual aspects of video production speed and TikTok’s speed of expansion. The impression of TikTok’s speed could still be caused by at least two things: 1. the average shot length of a TikTok video, 2. the amount of information conveyed through spoken word or text. Given complexity of the combination of spoken word, text in videos, text in subtitles, and text in the app interface, I’ll leave point 2 for another time. In the following lines, I will focus on the average length of a shot.

Average shot length is, in my opinion, a better indicator of speed than simply video length. Try to imagine a hypothetical social network where users could upload 30 second long videos, but only in one take. I dare to doubt that we would consider such a social network fast in any sense. We might even find it slow and boring. Especially compared to the US film and series, where the average shot length is between 3 and 5 seconds.

We can see this for ourselves thanks to Radomir Douglas Kokeš, who has been collecting data for a long time and publishing it on his blog. From his database, I was able to select a sample of films produced in the USA between 2014 and 2024 and calculate the variance of average shot lengths. I had 430 films and episodes in my sample. Sure, it’s not all that’s been produced, but better data just aren’t available.

The graph clearly shows that although the average shot length varies, it oscillates around similar values (average of averages).

Now let’s see what the average shot length of videos on TikTok is. Admittedly, I don’t have as large a database as Douglas. I collected the data in an unsystematic way one afternoon by sitting down at my desk with TikTok on my smartphone, turning on screen recording, and recording one video from start to finish for about 25 minutes. I then uploaded the file from my phone to my computer and took the classic shot length measurements I’m used to. For each video, I noted the lentg and the number of takes, from which I got the average shot length. In total, there were 19 videos in my sample (including two commercials, two split-screen videos, and five videos that were more like slideshow photographs).

The average shot length of videos on TikTok is longer than the average shot length of American movies. While the median is similar, the boundaries for the third and fourth quartiles are shifted by seconds.

Of course, one could argue that this is due to the sample, and that if I had measured on a different day or in someone else’s recommendation algorithm, I would have gotten different numbers. Sure.

On the other hand, there are arguments that the higher average shot length for TikTok videos may not be accidental. One of the reactions of our eye movement to editing in film is to reorient our gaze to the center of the screen. Research shows that viewers of portrait format videos (which is the format on TikTok) exhibit a weaker central bias than viewers of landscape videos (the format of movies and TV shows). I don’t know what videos specifically the measurements were taken on, but the weaker central bias could indicate a smaller number of cuts after which our gaze turns to the center.

Anyway, I want to repeat the measurements in some time to make sure. For now, I’ll go with the measured data and therefore…

In terms of average shot length, TikTok is simply slower than American movies and TV shows. It is not a fundamental difference, but it is there. When you think about it, it’s not really surprising. On TikTok, many of the videos are shot in one take (I had 6 videos in one take in my sample). These videos will inevitably slow down the TikTok experience and increase the average shot length. But in a way, they are the simplest thing a creator can do and therefore the most typical.

Well, to summarize. Some viewers seem to get the impression of speed from the TikTok videos. This impression is so intense that it has made its way (in a form of intuitive claims) in to academic papers. The problem is that we don’t know how to quantify this impression. For now, the only measurable value is the short duration of the videos, but I don’t think that is relevant evidence of the impression of speed. Especially when the average shot length is higher for TikTok than for the average American film. I therefore put more hope in the amount of information (text + speech) conveyed in the videos, but I’ll leave that for another time.
March 3, 2025

analysis, ASL, editing, film, movies, social-media, style, tiktok
David Chalmers (2022) Reality+: Virtual Worlds and the Problems of Philosophy

I decided to mix my reading about TikTok, social networks and cognitive psychology with a few philosophical books. In the case of Chalmers in particular, I initially felt that I might not be too far off thematically since he addressed the topic of virtual reality in his last book. Well, I was a bit mistaken. Chalmers has very different interests than I do, and he clearly tends to address problems of ontology, epistemology and ethics. In the context of TikTok, especially in the context of the current debate about whether or not to ban it, I found only one passage explicitly related. But I want to comment briefly on the rest of the book too.

First of all, it’s absolutely brilliantly written. In fact, I can well enough imagine that if this was what teaching philosophy in high schools was like, philosophy would have a very different reputation. Chalmers not only displays a deep erudition in Western philosophy, but also makes excursions into the non-Western philosophical tradition and especially into pop culture (especially science fiction literature, but also films such as The Matrix, The Thirteenth Floor, The Truman Show or series such as Star Trek: The Next Generation). Thinking about and through virtual reality (at least in the form of thought experiments) then leads him to rethink many philosophical concepts. Some of these – Plato’s Theory of Forms or the theistic conception of the world – are rather bizarre in the tradition of naturalised analytic philosophy. Chalmers approaches all of them with an open mind and is willing to grant them some persuasiveness in the context of his argument. If one of the functions of philosophy is to open minds and develop critical thinking, here it succeeds perfectly.

But now to the chapter on Value, where I find several points to consider in the case of the current discussion of TikTok. Recall that a few weeks ago it looked like TikTok was going to be banned in the US, then it didn’t even run for half a day before the new US President decided that things might be quite different. The case is summarized on wikipedia. What I found most interesting about the discussion was how the arguments for the ban were layered. We could see a diverse range of opinions covering national security, data protection, but also the dangers of TikTok for child users. I’m not competent to judge the extent to which TikTok can endanger America or damage the minds of children, and I don’t get the impression that there is a consensus on this. Let’s leave aside the legal, political and social dimension of the debate and think about whether TikTok has any value to the individual. Specifically, then, I will consider four possible values that Chalmers considers in the context of virtual reality.

In the chapter, Chalmers works with four traditional approaches to what it means that something is good for someone: hedonism, desire-satisfaction, social, and objective-list. Let’s look at what these approaches tell us about TikTok.

First, hedonism, which can simply be understood to mean that a thing is good if it brings more pleasure than pain. This is a bit of a problem with TikTok in particular. It brings satisfaction to its users which can result in addiction in 5.9 % of users. but for some individuals this can lead to a destructive, daily interaction with an app that satisfies them but potentially develops mental illness in some users as suggested by meta analysis.

Second in line is desire-satisfaction, or the approach that argues that a good life is one that brings about the fulfillment of our desires. Here we do not get simple hormonal satisfaction in the brain causing addiction to TikTok, which would again be contrary to a good and worthwhile life. Desire-satisfaction is probably the most advocated approach to value, promoted by the users themselves. Certainly not all of them, but a significant portion of them. Desire-satisfaction is implicitly present in all the motivational self-help videos, investment videos and exercise videos that are on TIkTok. I can’t judge whether this approach to values is correct, but TikTok, and by extension other social networks, are the venues through which desire-satisfaction spreads. And it only spreads because it finds a response from users who are willing to spend money on manuals, consultants and coaches to help them achieve financial independence, mental stability and a beautiful body.

The social perspective argues that the value lies in connecting with other people. Although social networks are often criticized for distancing people and creating moats in society, they are undoubtedly a tool that allows each of us to be in touch with family and friends at almost any time. For example, I can stop typing now and ask my wife Kristýna how many of her friends she has communicated with on social media today. The question is whether TikTok, which is primarily for sharing videos, offers social value. Here, though, it may just be a generational issue. While I wouldn’t be able to use videos to communicate operationally because I would be thinking through the angle, composition, and exact script of what I’m saying, some of my students already talk about making videos online as something natural. So at the very least, I don’t want to deny TikTok a social dimension. On the other hand social interaction is via TikTok and not with TikTok. Interaction with app and deep scrolling are understood as destructive practices.

And finally, the objective-list, which is the most subjective of all approaches. Even if we agree that the values are knowledge, friendship, and fulfillment (as Chalmers writes), we can never agree on whether TikTok helps us towards or away from those values. Whether TikTok serves an educational function is disputed (are student questionnaires a relevant method when we consider, that they may be already addicted to TikTok?), and whether the friendships on TikTok are real is also hard to agree on. I, for one, may be convinced that TikTok does not belong in the hands of children, but that does not mean that contact with TikTok will automatically damage their brains. In doing so, I feel that the current discussion about banning TikTok is being conducted on a moral level through the most vague objective-list approach to values.

In conclusion, let me just summarize that from an individual perspective, TikTok does not strike me as a fundamentally immoral application. Of course it has risks, of course its use can be dangerous for certain groups, but we could probably say that about all social networks or tools in general (guns, cars, staircases). I hope the political and social arguments of the proponents of banning TikTok are more convincing.

And if we look away from TikTok and look at short videos in general, their value is no less than that of other forms of audiovisual (information, advertising, communication, entertainment, or even art…). The problem is obviously in the platforms and may remind us of the critical perception of Hollywood. But this means that banning one platform won’t solve anything, because people will find another, as happened with the migration of Americans to Red Note.

February 11, 2025

David Chalmers, philosophy, social-media, tiktok, values