Why Captchas have gotten so difficult

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. The problem with many of these tests isn’t necessarily that bots are too clever — it’s that humans suck at them

The literature on CAPTCHA is littered with false starts and strange attempts at finding something other than text or image recognition that humans are universally good at and machines struggle with. It’s possible a similar future is in store for CAPTCHA, the most widely used Turing test in the world — a new arms race not to create bots that surpass humans in labeling images and parsing text, but ones that make mistakes, miss buttons, get distracted, and switch tabs.

Source: www.theverge.com