This is how the 'I am not a robot' Captcha test really works

It’s the bane of our life for many of us just looking to complete an online form. Still, the technology behind the common Captcha test – the one that asks you to confirm “I’m not a robot” before getting you to select all the hills and traffic lights in a set of blocks – is pretty impressive.

And that’s before you learn that Captcha actually stands for something: Completely Automated Public Turing test to tell Computers and Humans Apart.

The Turing Test, created by Second Word War codebreaker Alan Turing, concerns a test which distinguishes between man and machine.

Thankfully, the ‘quite interesting’ factual entertainment show QI had an explanation of Captcha during an episode of the quiz, in which host Sandi Toksvig explained: “Ticking the box is not the point; it’s how you behaved beforeyou tick the box that is analysed.

“To be honest, I can’t tell you all the details - because they keep it secret, because they don’t want people trying to cheat the test - but broadly speaking, you tick the box, and it prompts the website to check your browsing history.

“Let us say, for example, just before you ticked the box, you watched a couple of cat videos; you liked a tweet about Greta Thunberg; you checked a Gmail account before you got down to work… all of that makes them think that you must be a human.”

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So what about ticking the box? Apparently, that action could even help the test determine if you’re a human based on how you moved the mouse.

How the internet's 'I Am Not A Robot' form ACTUALLY works | QI - BBCwww.youtube.com

Toksvig concluded that regularly clearing your browsing history or using ‘incognito mode’ might therefore lead the test to believe you are a robot.

To this, panellist David Mitchell replied: “That is not the sign of a robot; that’s the sign of a w*****.”

That’s not a fact, by the way – we just thought it was funny.

And now you know…

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