You may be certain you’re not a robot, but a robot could be programmed to think that. Existential crises aside, determining which users are and are not robots is a complex task for web services. Go too easy and bots could flood in; make the test too hard and users will get frustrated and leave. The text transcription CAPTCHA has traditionally been used to make that determination, but Google has created a number of less annoying versions of this tool with its reCAPTCHAs. Now, it’s making reCAPTCHA even easier for humans. If you’re a human, you probably won’t see Google’s human-confirming dialogs at all.
The earliest CAPTCHAs (which stands for Completely Automated Public Turing test to tell Computers and Humans Apart) were just images of distorted text that were difficult for machines to read. However, spam bots have gotten a lot smarter over the years. Luckily, Google’s machine learning algorithms have improved as well.
There are several versions of the Google reCAPTCHA, including the old distorted text test. Google has also used reCAPTCHAs as a way to confirm Street View addresses by having humans read images of the address placards. Perhaps most famous is the checkbox. Simply click the box and Google uses your mouse movements, IP address, and other bits of data to make sure you’re a human. Google calls this a “No CAPTCHA reCAPTCHA.” There is an online demo of that one if you want to refresh your memory.
With its latest version of reCAPTCHA, Google has improved its detection algorithms with machine learning and advanced risk analysis. When you load a page protected by this system (because you are a human and definitely not a secret robot), it should just load immediately without any additional interaction. That means no reading warped text, and no checkbox. It’s still doing some of the same things behind the scenes like checking your IP address and analyzing the way the mouse cursor moves. It simply does that in the background “before, during, and after a user’s engagement with the CAPTCHA.”
Google is a little vague on the details, but that’s probably intentional. Giving too much information about what the system is looking for could make it easier to circumvent. When websites switch over to the new invisible reCAPTCHA, you probably won’t see the challenge at all. If there’s something suspicious and Google can’t be certain you are a human, the checkbox version may still appear. Website operators who want to give invisible reCAPTCHA a shot can opt-in right now.