Interesting post from Google on their update for reCAPTCHA.
The short story is that they are replacing the current CAPTCHA method (distorted image-text or distorted audio) with a simple tickbox for “I am not a robot”. They then use some heuristics based on IP address, browser config, mouse pointer behaviour etc. to guess if you are a robot.
That bit about using mouse movements to analyse your human-ness obviously rang alarm bells, and I couldn’t find an example easily, so I created an example.
At first glance, it is keyboard accessible, has appropriate ARIA attributes (which are needed as they use a span for a checkbox), and it didn’t fail when I only used the keyboard.
Overall, it looks like an important improvement from an accessibility point of view. If the heuristics fail you then you get the traditional CAPTCHA approach, however, that should be a lot less frequent.