Over the past year or two, the internet has become increasingly tailored so we see only what it thinks we want to see - which in most cases means what Google wants us to see. We investigate what's happening, and how you can prevent your web search being filtered.

Before the internet existed, our main source of news and current affairs was newspapers and TV broadcasts. We saw and read only what the editors decided we should, and our view of the world was shaped by this information. If a story was deemed too boring - let's say the African famine - it wouldn't be reported and you'd instead see coverage on something else.  

The internet and Google changed all that. There were no editors, so the information was freely available: all you had to do was search for it. However, whether you realise it or not, today's search results are personalised so you don't necessarily get the same view of the world as your friends, family and colleagues.

Algorithms and filters use data about you, such as your location, age, gender and preferences to deliver a set of results they think will you'll want to see. But is this a good thing?

In some cases, it may be exactly what you want. Social networks such as Facebook filter out the stuff you would have skipped over and let you quickly digest updates from close friends. However, since all this personalisation is largely invisible, how do you know what you're missing out on? Can an algorithm be trusted to make the right choices about which information you see?

In this feature, we'll look at exactly what's happening and explain some of the steps you can take to avoid or disable these filters.

Filtered search: Google searches

You'd be forgiven for thinking that a Google search for a particular word or phrase would return the same results regardless of who was searching for it around the world. That's far from the case, though, and rightly so. If you search for 'passport application' and you're somewhere in the UK, you'd want to find information that relates to applying for a UK passport.

You're unlikely to be interested in finding out how to obtain a passport in any other country, so Google uses information about your location to tailor its results to provide results it thinks are the most relevant.

This has been happening on a country or continent basis for years, but recently the algorithm has been updated to become a lot more personal. It isn't only your location which search engines such as Google use to filter results. Your search history, online contacts, the browser you're using and even the type of computer is factored in and, while the change in results can be subtle, they can sometimes be radically different.

Take the two results lists below as an example. Both searches were run at the same time, one in London, and one in Sydney. Although both start with the Wikipedia entry for Jim Martin (the guitarist in Faith No More), and have the same image results (in different orders, note) the rest of the results are completely different. It's clear which is the Australian search, but the UK search is oddly filled with US-based websites rather than UK-related results.

Jim's search in London

Edd's search in Sydney

You don't need to be signed in to a Google account to see personalised results, either. There's enough information about where you're based, plus search history to tailor searches, but things get even more personal when you do sign in. As we showed last month in our Ultimate Guide to Google, the firm has many services which all use the same account details. Not all are brimming with useful information, but if you use the Google+ social network, it's a different story. See also: How to use Google+

Here, Google knows as much as you choose to reveal about yourself. Whether it's information you post in status updates, links and videos you share, or photos you upload, it's relatively easy to understand what makes you tick and prioritise certain websites over others in your list of search results.

If this is all something of a revelation, you might decide to stop using Google. That's certainly one way to stop your data being used to tailor results, but the bad news is that just about every search engine does it. Yahoo and Microsoft Bing both use personalisation algorithms, although Yahoo's has an element of human input, so it's listings aren't entirely generated by machines.

The main problem is that few people realise that any filtering is taking place as it happens automatically. You won't see a warning or the option to opt out. This is the potential downfall in personalisation, as you may not be aware that you're no longer in the driving seat when it comes to what you want to see on the internet.

Some people argue that it's a form of censoring, while others - including the web's inventor Sir Tim Berners-Lee - say it can give you a twisted view of the world and can leave you isolated as the information fed to you is more and more personalised.

Filtered search: Social networks

This is especially true of Facebook, which has filtered its News Feed for a while now. As we said at the beginning, the aim is to put the information you want at your fingertips: the motives behind filtering content are largely blameless, but personalisation can still have drawbacks.

Facebook uses an algorithm called EdgeRank which decides what is and isn't shown in your News Feed. If you've used the social network for a few years you'll have noticed when EdgeRank was introduced (and likely been confused or upset by the change). Instead of a chronological list of status updates, the News Feed switched to a filtered one where 'important' updates (currently called Top stories) were prioritised and put at the top.

Facebook EdgeRank

Without getting into the technical details, the algorithm attempts to calculate what you'll want to read about. It looks at who you interact with most and puts status updates, photos, videos and links from those people high up in your News Feed. It also tries to figure out what else you'll want to see from people you don't regularly engage with, such as updates family members or brands you've 'Liked'.

This is all well and good, but it doesn't encourage you to maintain friendships with people you don't interact with regularly: they tend to disappear from view entirely so you won't see status updates when they post something and won't be prompted to get in touch with them.

To appreciate how much filtering is taking place, browse your list of friends and see how many of them appear in your News Feed. Chances are it's only a fraction of the total. Naturally, there will be some people who rarely post an update, but it should still be obvious that you're not seeing the full picture.

Filtered search: Twitter

Even Twitter has been accused of filtering with its trends, since it panders to users' obsession with what's new rather than what's important. Twitter also tailors search results in the name of making it easier to "get a sense of what's happening right now, wherever your curiosity takes you". But instead of enabling you to discover things, personalisation tends to do the opposite and can prevent you from seeing new things.

Filtering  also affects which online ads you see. It's pretty unnerving when you realise you're looking at adverts for precisely the product you looked at on Amazon a week ago. It's certainly clever advertising, but again, it means you're potentially missing out on seeing new products that you might also be interested in.

Next page: Are personalised results such a bad thing?

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