Mark Styles has posted over at Weblog Tools a post on CAPTCHAs (wikipedia’s page on them here) which makes some good points about why they might not be the best solution for stopping comment spam on a blog. Here’s a few of his main points:
Any extra work required to comment is likely to deter some people from commenting at all.
Sometimes the images are so distorted they’re almost impossible to read, even with perfect eyesight.
CAPTCHAs are hackable. Spammers are smart, they can get past many of our barriers.
Visually impaired users are completely excluded (although there are audio CAPTCHAs available now).
