Google have now developed a much simpler system, called "reCAPTCHA V2", which many sites have changed to, and which operates differently and is very user-friendly - most of the time. My experience with sites that use it is that every now and again its algorithms produce an uncertain result, and it defaults to a visual CAPTCHA (usually the one requiring clicks on a grid of photos where there are road signs, cars or shop fronts (that's the one referred to by Pilot Frans - which does indeed require one to understand the question, though they often repeat the same questions with different photos)
https://support.google.com/recaptcha/?hl=enhttps://www.google.com/recaptcha/intro/Whether there are technical down-sides, I do not know -
but all this has been referred to IT, as I mentioned the other day, and we will get it sorted asap.