Block Carefully

A couple of years ago, I posted a slight criticism of Elon Musk that led prominent venture capitalist Marc Andreessen to block me on X. Since then, I have been unable to view his posts¹, which is a shame because I valued his thoughts and opinions.

Today, X engineering announced changes to the “block” feature:

Soon we’ll be launching a change to how the block function works.

If your posts are set to public, accounts you have blocked will be able to view them, but they will not be able to engage (like, reply, repost, etc.).

I’m glad to see this change from X. The block feature has always been flawed, and this makes it slightly less so.

On buttons and algorithms #

The block button is a problematic feature on X because it’s used so often, so cavalierly, and by so many people that it’s difficult to determine whether someone was blocked due to genuine harassment or simply because the blocker disagreed with one (or all) of the blockee’s posts. As a result, being blocked doesn’t provide a high-quality signal for the algorithm when generating a user’s feed—though, I’m reliably told, it’s used for that purpose anyway—and it’s not very helpful for community moderation either.

Feed algorithms use tons of automated and aggregated signals to shape a user’s feed, and these signals are almost entirely hidden from users to preserve the illusion that their feed is generated by magic. But I think we’re now at a point in the evolution of these algorithms where users should be given some insight into how their behavior impacts the content they are shown. It’s not always intuitive.

For example, I doubt many people know that scrolling behavior on Instagram is heavily used to feed the algorithm–if you’re scrolling through your feed and pause on a post for a few moments, the algorithm ingests that behavior and uses it as a very strong signal that you want to see more posts like that one. Similarly, YouTube’s algorithm uses the passive metric of watch time on a video to determine your interest, and–contrary to popular belief–practically ignores the like button. The software is watching you and making assumptions about your behavior that may or may not be accurate–and then it’s altering what you are exposed to in your feed.

A few weeks ago, Elon Musk explained that “one of the strongest signals” to the X algorithm that you like a post is if you click the “share” button. This is scary, because a person or team at X somehow decided that clicking “share” is a positive signal, so they built it into the algorithm that way. As it turns out, a lot of people use the share button for other reasons, such as sharing posts they are outraged by, which can seriously distort their feed. Users, of course, were never told that their sharing behavior was being monitored and fed into the algorithm, let alone that it was one of the strongest signals.

I don’t think most people consider how the block button impacts the algorithm, either, but it does, so using the button changes the content the algorithm exposes to you. How big of an impact the button has is a secret inside of a black box. So when people use the block feature like Andreessen did with me, presumably to avoid seeing more of my posts, they might inadvertently prevent themselves from being exposed to similar posts from other people. Very slowly and completely unwittingly, they may eventually find themselves in an echo chamber of their own design, filled entirely with posts discussing only one side of every story.

The X algorithm is particularly scary because it has the ability to radicalize people by reinforcing their beliefs subtly, over a long period of time. Most of the new generative AI companies are so obsessed with preventing this kind of human interference that they literally build their products around safety. Are the algorithms at X treated with the same degree of concern? I kind of doubt it.

With every block, with every share, with every action you take–knowingly or not–the algorithm may be reducing the diversity of thought you’re exposed to just a little bit more, until one day you might look back and see that it interfered with your mind–and your opinions.

Block carefully.