I am not a Robot! - the access implications of Google’s new Invisible reCAPTCHA

Google has taken one more step towards a fully-automated bot-detection system with the launch of ‘Invisible reCAPTCHA’ - which hopefully spells an end to having to prove that you are not a robot all of the time. But what are the accessibility implications?Image of circle crossed robot dalek
 
What is CAPTCHA?
CAPTCHAs (or Completely Automated Public Turing test to tell Computers and Humans Apart) is a type of challenge-response test used to determine whether or not the user is h