This weekend we learned that Facebook had deliberately manipulated the emotional content of 689,003 users' news feeds as part of an experiment to see what kind of psychological impact it would have. For one week in January 2012, some users saw chiefly positive stories (kitten videos, brownie recipes and assorted LOLs), while others were force-fed despair (breakups, health woes and seal-clubbing holiday snaps). And guess what happened?

"The results show emotional contagion," decided the scientists.

Emotional contagion is what we used to call "empathy".

"When positive expressions were reduced, people produced fewer positive posts and more negative posts; when negative expressions were reduced, the opposite pattern occurred. These results indicate that emotions expressed by others on Facebook influence our own emotions."

In other words, the fine folk at Facebook are so hopelessly disconnected from ground-level emotional reality they have to employ a team of scientists to run clandestine experiments on hundreds of thousands of their "customers" to discover that human beings get upset when other human beings they care about are unhappy.

But wait! It doesn't end there. They also coolly note that their fun test provides "experimental evidence for massive-scale contagion via social networks". At least we can draw comfort from the fact that this terrifying power to sway the emotional state of millions is in the right hands: an anonymous cabal of secret experimenters who don't know what "empathy" is.

Other experiments Facebook has been conducting in secret almost certainly include the following:

1) Dishonestly convincing a randomly targeted user that one of their siblings has just died, in order to see what their face does. Conclusion: it leaks fluid from the nasolacrimal ducts and emits an ape-like cry believed to denote personal anguish.

2) Secretly activating random users' webcams in the runup to bedtime to determine what a human being looks like when it sheds its external fabric layer.

3) Dispatching an intern to kidnap and blindfold a random user, drag them to a forest, force them at gunpoint to dig their own grave, shoot them in the back of the head, cover the body with soil, drive away at speed and lie low in a motel for a few weeks to discover if they're really cut out for this shit.

4) Igniting a global race war using animated gifs.

Facebook's sinister mass manipulation may be chilling but it's hardly surprising. We don't use the internet; it uses us, and the more personalised any online service appears to be, the less it thinks of you as a person. The experiment is evidence that you and your hopes and dreams are nothing but a miniscule, malleable blip as far as Facebook is concerned: a pocket-sized data mine with functioning nostrils.

They're all at it. Google tracks your every move, knows where you live, and is probably about to send a driverless van round to take you to work in its silicon mine. Amazon plans to launch drones that'll fly over your garden dropping packages containing algorithmically-selected items you haven't even ordered yet onto the heads of your children. Netflix knows damn well you rewound the film to look at that actor's bum, and it'll email your parents right now to tell them unless you agree to a 40% price hike.

I jest. Just. But such a world is clearly inbound, even if it's not always clear whether the mass manipulation is deliberate or not. Take Twitter. Twitter recently updated its iPhone app, so now it automatically notifies you when certain events occur, whether you're using it at the time or not. So if lots of people retweet something you've said, or a celebrity mentions you, it'll interrupt whatever you're doing with the equivalent of a text message. You're trending in Bristol! Kevin Spacey favourited your tweet! It's a pat on the head; a reinforcement. You did good. Have a marshmallow.

It's a positive reinforcement system: one that, over time, seems doomed to subtly mould the personality the user projects online, like a stream gradually sculpting a pebble. And it's not just about social approval. Aside from humour, the best way to guarantee a reaction is to provoke others – either in agreement or disagreement. Rather than bringing us together, it seems almost perfectly designed to encourage polarisation. The end result: diametrically opposed networks of nudged and prodded pebble people gently rattling together in agreement, clashing loudly when they encounter dissent.

That's depressing. So you go on Facebook to complain about it. To warn humankind. But it seems humankind doesn't want to know. All you see is a steady stream of your friends leaping about on bouncy castles, "liking" things and posting the sunniest Carpenters' lyrics they can think of. The positive imagery enters your bloodstream and you start to feel better. You put your feet up and forget about it. You update your status to "lovin' life!!!!!" and munch a chocolate biscuit. And somewhere in Facebook boss Mark Zuckerberg's underground control centre, one more tiny pixel in the immense constellation of human data points that sprawls like a wondrous cloud galaxy across a wall of screens the size of the Hoover dam winks from red to green, taking him one further microscopic step toward what he secretly likes to think of as "phase two".