When you share a news article with a friend and they haven't heard of the story, or when you mention a product and they're confused you're seeing it advertised—there's a moment of mild cognitive dissonance. You're both online. You use the same apps. How is it that you appear to inhabit different information environments?
The answer is that you do inhabit different information environments. Completely, deliberately, and by design. The idea that the internet is a shared experience—that we are all, in some meaningful sense, looking at the same thing—is one of the most consequential myths of the digital age.
Two people opening the same app at the same moment see entirely different content. They have different feeds, different recommendations, different trending topics, different ads. The internet isn't a shared space. It's a set of personalised environments that happen to run on the same infrastructure.
How Personalisation Actually Works
Every major platform uses some combination of your behavioural history, your demographic profile, your social graph, and your device characteristics to determine what you see. The degree of personalisation is more extreme than most users realise. A 2023 study by the Mozilla Foundation tested TikTok's algorithm by creating accounts with different stated interests. Within 40 minutes of use, accounts set up to appear vulnerable—expressing interest in content related to sadness or low self esteem—were being shown an escalating spiral of distressing content that accounts without those signals were never exposed to. Same app, same interface, radically different experience.
The Political Dimension
The consequences for political discourse are particularly serious. Eli Pariser coined the term "filter bubble" in 2011 to describe the tendency of algorithmic personalisation to expose users primarily to information that confirms their existing beliefs. The mechanism is straightforward: content that generates agreement produces stronger positive engagement signals than content that challenges. Algorithms learn this and serve more of it. Over time, two people with different political starting points will be shown increasingly divergent realities—and may come to hold different beliefs about basic factual questions, not just different opinions.
What It Means for How You Navigate Online
The practical implication: your feed is not a window onto the world. It is a mirror, gradually refined to show you more of what keeps you engaged—a function of your past behaviour, not of what is objectively important or true. When you feel informed because you've been scrolling for an hour, that feeling may be a product of confirmation, not comprehension. The corrective is to actively seek out perspectives beyond the algorithm's default curation: follow people whose views differ, use search rather than feed for important topics, and treat the absence of something from your feed as a data point about the algorithm, not about the world. What you don't see is as revealing as what you do.
