Have you ever watched a video or movie because YouTube or Netflix recommended it to you? Or added a friend on Facebook from the list of “people you may know”?

And how does Twitter decide which tweets to show you at the top of your feed?

These platforms are driven by algorithms, which rank and acclaim agreeable for us based on our data.

As Woodrow Hartzog, a assistant of law and computer science at Northeastern University, Boston, explains:

If you want to know when social media companies are trying to dispense you into advice advice or agreeable more, the answer is always.

So if we are making decisions based on what’s shown to us by these algorithms, what does that mean for our adeptness to make decisions freely?

What we see is tailored for us

An algorithm is a agenda recipe: a list of rules for accomplishing an outcome, using a set of ingredients. Usually, for tech companies, that aftereffect is to make money by acceptable us to buy article or befitting us scrolling in order to show us more advertisements.

The capacity used are the data we accommodate through our accomplishments online – advisedly or otherwise. Every time you like a post, watch a video, or buy something, you accommodate data that can be used to make predictions about your next move.

These algorithms can access us, even if we’re not aware of it. As the New York Times’ Rabbit Hole podcast explores, YouTube’s advocacy algorithms can drive admirers to more acute content, potentially arch to online radicalization.

Facebook’s News Feed algorithm ranks agreeable to keep us affianced on the platform. It can aftermath a abnormality called “emotional contagion”, in which seeing absolute posts leads us to write absolute posts ourselves, and seeing abrogating posts means we’re more likely to craft abrogating posts — though this study was arguable partially because the effect sizes were small.

Also, alleged “dark patterns” are advised to trick us into administration more, or spending more on websites like Amazon. These are tricks of website design such as hiding the unsubscribe button, or assuming how many people are buying the artefact you’re attractive at . They subconsciously nudge you appear accomplishments the site would like you to take.

You are being profiled

Cambridge Analytica, the aggregation complex in the better known Facebook data leak to date, claimed to be able to contour your attitude based on your “likes”. These profiles could then be used to target you with political advertising.

“Cookies” are small pieces of data which track us across websites. They are annal of accomplishments you’ve taken online (such as links clicked and pages visited) that are stored in the browser. When they are accumulated with data from assorted sources including from all-embracing hacks, this is known as “data enrichment”. It can link our claimed data like email addresses to other advice such as our apprenticeship level.

These data are consistently used by tech companies like Amazon, Facebook, and others to build profiles of us and adumbrate our future behavior.

You are being predicted

So, how much of your behavior can be predicted by algorithms based on your data?

Our research, appear in Nature Human Behavior last year, explored this catechism by attractive at how much advice about you is independent in the posts your accompany make on social media.

Using data from Twitter, we estimated how anticipated peoples’ tweets were, using only the data from their friends. We found data from eight or nine accompany was enough to be able to adumbrate someone’s tweets just as well as if we had downloaded them anon (well over 50% accuracy, see graph below). Indeed, 95% of the abeyant predictive accurateness that a apparatus acquirements algorithm might accomplish is achievable from friends’ data.