Do you mind explaining what you mean by "slot machine" in this context? I'm not a TikTok user, but I'm sometimes on Facebook and other "feed" sites, and I don't fully grasp how gambling comes in to play.
The scientific term is Variable Rate Operant Conditioning. It's where you press a button, have some chance of a reward (winning money or seeing a video you like) and can immediately play again. It's the same mechanism.
From rats on up to humans this is known to be an extremely addictive behavioral pattern. Social media like Tik Tok can perfectly balance how much reward to give you to keep you engaged while filing the non-reward results with ads and other messaging they want you thinking about.
Are rewards in nature more valuable if the outcome is not certain? Or is that a trait that stuck to humans because people who try again and again learn better?
I mean even HN employs that pattern (though not necessarily intentionally). Whenever you refresh the page you have a random reward in the form of gain/loss of karma or comment replies.
You're comparing a no-ads[0], slow-moving, text-based feed (that has a maximum number of content pieces on the main pages at any given time) designed around fostering a specific tech-related community to an infinite, doomscrolling, video-based brainwashing machine filled with ads, violence, fear-mongering, propaganda, and softcore pornography designed as a skinner box to maximize engagement and consumption. HN has plenty of problems, but it is not even remotely comparable to TikTok/IG/etc.
Does HN strategically push or withhold desirable content on each refresh in the most addictive way possible specifically to keep people refreshing the page and prevent them stopping?
I think intent matters for a lot here, as does who/what is pulling the levers. If popular content organically rises to the top because people like it that's not really a problem, but if content is artificially pushed to the top or hidden entirely to push an agenda that could be an issue.