In December of 2014 Google Online Security announced switching to No CAPTCHA reCAPTCHAs Google no longer deemed the ability to read distorted text as sufficient. Optical character recognition software and artificial intelligence (AI) are nearing the level of success that some humans would be jealous of. I expect we will see a switch to Two-Factor Authentication (2FA), which is more time-consuming and you have to give up some of your personal information like for example a phone number or email-address.”]
Source: https://blog.malwarebytes.com/cybercrime/2015/02/logging-in-and-captcha/