Neil Turner's Blog

Blogging about technology and randomness since 2002

Compassionate CAPTCHAs?

I think you all by now know my opinion about CAPTCHAs – those images with numbers in that you have to type out to prove that you’re human (more details here). They’re fine if you use a browser that supports images, and that your eyesight is good enough to allow you to read them, but that does not include everyone and as such it puts form submission beyond the reach of a significant number of people. As such, I’ve avoided them on here.
But last night I had an idea. I could still use CAPTCHAs, but if the user was unable to see the code in the image, instead of the comment being blocked it would be forcibly moderated. That way, the spam would not get shown, but any legitimate comments could be held and then approved by a human. I could also allow approved TypeKey users to skip the CAPTCHA, on the basis that once their initial post on here has been approved it’s likely that they’re not going to be spammers.
SCode is, as far as I know, the only CAPTCHA plugin for Movable Type and at the moment it lacks the functionality that I described above. But maybe this ‘hybrid’ approach will get around the problems that CAPTCHAs have had in the past.


  1. I think the worst captcha i’ve come across so far is slashdot’s. It seriously took me about 10 attempts to get it right, absolutely terrible, the 1 is indecipherable from an l and so forth.

  2. On the LiveJournal one it has a message to type Audio if you can’t read it and it’ll play an MP3 of the word.
    A good comprimise?

  3. For I modified scode (badly as I don’t know perl!) to output a plain text captcha.
    Whilst it’s techically possible for an automated script to pull the code out, Pewari hasn’t had any comment spam since implementing it…
    I like the idea of audio alternative too.

  4. The idea of going to moderation if the captcha isn’t entered correctly is a great idea! It allows the masses to post as they normally would, but the ones who can’t reproduce the captcha (I agree with MRKisThatKid, I have had captcha’s that I haven’t been able to reproduce either) a chance to post as well, just won’t show up right away.
    I don’t know if I have mentioned this here before, but I have also seen captcha’s where they are text, just like the rest of the form, but it’s a simple math problem instead of a graphic. Something like:
    Enter 5+95:
    I suppose that there is an extreamly small percentage of people that wouldn’t be able to pass that, but really, do you want that person posting a comment anyway? 🙂 Plus, you could still moderate a comment that wasn’t answered properly.

  5. Or three buttons set out like
    [Button 1] [Button 2] [Button 3]
    in red, green and blue colours. And then random prompt such as “Press the green button” “Press the left most button” “Press the button labelled Button Three”.
    Or rename the “Post” button so it’s renamed as “ok” and then create a new button labelled ‘Only press here if you are a spammer’ and hide it with CSS. If you get a form submitter by using the ‘new’ ‘post’ button, it’ll be a ‘bot.

  6. The problem with coloured buttons is that there are people out there that are colour blind. Accessability really makes things like this very hard to deal with.