I’m Not a Robot! So Why Won’t Captchas Believe Me?

Like so many this winter, Norine McMahon was searching for a Covid-19 vaccine appointment, hitting Refresh on her browser continuously. The Washington, DC, resident was elated to find an opening in late February, but delight turned to disappointment when she failed the captcha user-verification test, even though she swore she entered the letters and numbers correctly.

“Then I would do it really slowly to make sure I was getting it correct, because of course the pressure is on. It happened a dozen times. The captchas weren’t working,” says McMahon, 61, a facilities director who gave up that day but eventually secured an appointment.

The captcha chaos with DC Health’s portal was one of several technical problems widely reported at the time. But captchas have been frustrating users since long before the pandemic.

“Captcha” stands for “completely automated public Turing test to tell computers and humans apart.” The Turing test was created in 1950 by Alan Turing, a British mathematician considered a founding father of artificial intelligence, to help determine whether a computer can demonstrate intelligent behavior similar to a person. Turing called it the “imitation game.” Luis von Ahn helped develop the modern captcha as a grad student at Carnegie Mellon University, where he is now a consulting professor, and later invented reCaptcha, which Google acquired.

The goal of captcha is to create tests or puzzles that humans can solve but bots can’t—so you, a mere mortal, might have a shot at a decent seat to a Springsteen concert when they go on sale at 10:00.01 am.

It can be a tricky balance, especially as machines become more sophisticated.

“Usually artificial intelligence systems are capable of coping better than humans because, as an example, they don’t suffer from annoyance. They are infinitely patient, they don’t care about wasting time,” says Mauro Migliardi, associate professor at the University of Padua in Italy. He recently coauthored a paper summarizing 20 years of captcha versions and their effectiveness.

Google won’t say what share of the captcha market it has, but it appears dominant in the US, with the reCaptcha name seen frequently on various sites. For this story, Google requested that questions be submitted in writing and then answered them in writing, saying direct quotes could not be used.

Google has a reCaptcha “help” page, but its answers are underwhelming. One question asks, “This captcha is too hard,” to which Google answers, “Don’t worry. Some captchas are hard. Just click the reload button next to the image to get another one.” That help page also notes that Google uses captchas to train its AI, saying that the human effort that you and I put into solving them goes towards improving their products that digitize text, annotate images, and more.  

Google’s support page did not answer other questions so many ask, especially about the photo grid challenges. If there is a sliver of a bus in a square, do you have to click it? When selecting traffic lights, do you click the poles? When asked these questions, Google advised selecting the majority of squares that have the bus or traffic lights.