That's kind of the crazy part, there is no actual "psychological" tricks in the sense that they just train their recommendation algorithm to build your feed in a way that makes you spend as much time as possible (basically a glorified A/B testing on a massive scale).

With these types of algorithms, massive amount of data usually perform better than any underlying model you could have.

There's more to it. The short form content "crushes" what options are available, so it becomes much easier to classify you into buckets with similar people.

This is what actually drives the "We talked about X and then I got an ad for it" effect. You talked about X because something you were presented with prompted your brain to think about it, and the platform knows that people in your cohort who were presented with that thing often navigated to X later, so it should show it to you to claim an impression for it. It doesn't actually have to figure out any connection of the prompting source to X.

But some people are somewhat immune to this populism. I find short form content like TikTok and Twitter/Bluesky to be actively anti-engaging. The format and medium and "Virality" mechanic drive constraints on content that are actively signal negative. Somehow my brain rejects it, even though I'm ADHD and have addictive tendencies for things like Youtube in general, novelty, and used to get extremely addicted to Reddit. I'm pretty snobby about media, so maybe whatever drives me to have that preference makes me likely to bounce off that kind of populism system. Maybe there's a biological component to Hipsterism, like a certain kind of anti-authority issue.

I strongly believe that making a product, media, or content more palatable to "General audiences" or similar large cohorts forces you to sand off all the edges, cut out any opinions or takes, and become far less palatable to a different cohort, possibly one that describes itself as having "Taste".

So in some sense, the platforms self select for people who are vulnerable to them, which simplifies classification somewhat as well, even though that is the vast majority of people. But TikTok would never find what I like because what I like cannot be found on TikTok. Notably, this includes creators who I follow like a lost puppy on youtube, because the ways you have to change and modify your output to "work" on TikTok make it worse in many ways.

I actually doubt it involves a lot of hacks and psychological trickery.

Given the concept of short-form videos, some of them will be viewed and shared more than others. Just promote those to everyone. People are not that different in what they find engaging. Maybe use a few broad demographic groupings to fine-tune things a bit.

I assume that the success of individual parts of the website are predicated on whether or not they contribute to the platform's addictiveness, and that's been gradually improved over time: moving an icon 5px to the left, or slightly increasing the font size of a certain element.

It just seems like a psychological war ground designed to entrap and monetize the user's attention, at all costs.