WHY CAPTCHAS HAVE GOTTEN SO DIFFICULT

At some point last year, Google’s constant requests to prove I’m human began to feel increasingly aggressive. More and more, the simple, slightly too-cute button saying “I’m not a robot” was followed by demands to prove it — by selecting all the traffic lights, crosswalks, and storefronts in an image grid. Soon the traffic lights were buried in distant foliage, the crosswalks warped and half around a corner, the storefront signage blurry and in Korean. There’s something uniquely dispiriting about being asked to identify a fire hydrant and struggling at it.

These tests are called CAPTCHA, an acronym for Completely Automated Public Turing test to tell Computers and Humans Apart, and they’ve reached this sort of inscrutability plateau before. In the early 2000s, simple images of text were enough to stump most spambots. But a decade later, after Google had bought the program from Carnegie Mellon researchers and was using it to digitize Google Books, texts had to be increasingly warped and obscured to stay ahead of improving optical character recognition programs — programs which, in a roundabout way, all those humans solving CAPTCHAs were helping to improve.

ALL THOSE AWNINGS THAT MAY OR MAY NOT BE STOREFRONTS? THEY’RE THE ENDGAME IN HUMANITY’S ARMS RACE WITH THE MACHINES.
Because CAPTCHA is such an elegant tool for training AI, any given test could only ever be temporary, something its inventors acknowledged at the outset. With all those researchers, scammers, and ordinary humans solving billions of puzzles just at the threshold of what AI can do, at some point the machines were going to pass us by. In 2014, Google pitted one of its machine learning algorithms against humans in solving the most distorted text CAPTCHAs: the computer got the test right 99.8 percent of the time, while the humans got a mere 33 percent.

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