If you’ve ever been on a website that requires some form of authentication, you’ve probably seen that tiny box that you need to click before proceeding any further or a code you need to type out. This seemingly demonstrates you’re not a machine, but have you ever wondered how it works, who might need it and why?
Far from being a sign of the government ‘spying’ on you, it’s more of a reassurance to the websites you’re using that you are indeed who you claim to be. It might surprise you to know that its story began right after World War 2! Its father was Alan Turing, a name you might know from having watched the amazing ‘Imitation Game’ a few years ago. He was a crucial help in fighting German forces by deciphering their messages and giving the Allies this information. He created the so-called ‘Turing test’, meant to determine whether the person taking it was a human or a robot, based on a party game. Imagine going to a party with your mates one night and by the end of it changing the history of computers!
(Image: wordstream.com)
Initially, the test would involve a man and a woman going into separate rooms, and a third person would have to guess who was where, by asking them questions. Turing extended the idea, by involving a judge that would converse with a computer and a man, and would try to tell them apart. This eventually evolved into the CAPTCHA test (Completely Automated Public Turing Test to Tell Computers and Humans Apart – now that’s a mouthful!) that we see on websites nowadays. These usually look like letters and numbers jumbled together, which are supposed to be different for each user.
Why does it work, though? Because the CAPTCHA words have to follow a set of basic rules which make it very hard for machines to read. These include distorting the letters and their background, showing them very close to one another or making them impossible to decipher unless the context is obvious to the reader.
More recently, a visual element has been added to the test, in the form of pictures you need to click with specific elements in it. If you’ve also been stuck for 15 minutes on a Google CAPTCHA trying to ‘select all the images that have a car in them’, you will know exactly what I mean! This more advanced form works because we are wired to recognize patterns, even where they don’t exist (like clouds that look like animals).
(Image: magazine.seats2meet.com)
So next time you see the little ‘not a robot’ box in the corner of your website, don’t look at it as a grim reminder that the world will one day be taken over by robots!
Sources:
Turing, Alan (October 1950), “Computing Machinery and Intelligence”, Mind, LIX (236): 433–460
Bursztein, Elie; Martin, Matthieu; Mitchell, John C. (2011). “Text-based CAPTCHA Strengths and Weaknesses”. ACM Computer and Communication Security 2011 (ACM Conference CSS’2011). Stanford University
Strickland, Jonathan. https://computer.howstuffworks.com/captcha.htm