If by “actually works” you mean “causes me to not comment on your blog and not bother to subscribe to it or read it in any future way at all”, then yeah, I suppose it could be said to work.

When I see that I have to jump through your weird hoops to comment, then I don’t comment. Instead, I leave and don’t return. And I’m not alone.

You’re perfectly welcome to like your system. I’m simply telling you that your system loses viewers, readers, and commenters. Being one of those that your system would lose, I am absolutely certain of what I’m saying.

Okay?

It if is working for you, great. Reality on the ground is that it does not work consistently or practically. People with more expertise, knowledge, and higher IQs than me have put it exhaustively through the test. If you are the exception, wonderful.

I know what a clever programmer *could* do. And I know what spammers are *actually* doing now, because the math problem actually works.

Not as a replacement for Akismet, but as an addition that saves me the trouble of reviewing a long “probable spam” moderation list every evening.

Sorry to say it, but outrunning the bear is not a reasonable goal; outrunning the other campers is.

On the IQ issue…if adding two numbers causes an smart person to forget their comment, then that person would type the comment first and the number last. Because that is the intelligent response.

CAPTCHAs are not handicap-accessible. Why alienate a large amount of the population?
CAPTCHAs drive away real commenters. I see a captcha, generally I don’t bother leaving the comment I had in mind unless it’s *really* worth my time trying to figure out your weird system.
CAPTCHAs were never intended to prevent spam. They’re actually being misused here, they were originally intended to distinguish between people and bots. But WordPress and other blogging systems actually *want* automated feedback from bots… namely feedback from other users blogs. Look at the number of pingbacks and trackbacks blogs get. You want to block SPAM, not “comments by other machines”. Focus on the problem at hand.
Oh, yes, CAPTCHAs actually don’t work. Virtually no spammer uses comment forms anymore. They use trackback mechanisms, which is expressly designed to allow comment-like input on an automatic basis. Your CAPTCHA doesn’t guard the backdoor.

The “simple math” trick approach also doesn’t work. A clever spammer/programmer can very easily compile a short list of questions and then put in the answers and get a ton of spam through your gate. Not to mention that it’s somewhat trivial to make machines actually capable of figuring out the answers to your questions. You can even have your spamming program just ask Google for the answer:
http://www.google.com/search?q=what+is+one+plus+four
http://www.google.com/search?hl=en&q=what+is+6+times+five

Unless your variations are way large and more complex than “simple math problems”, defeating your mechanism is trivial. And that assumes you didn’t leave the backdoor open in the first place, since spammers probably aren’t using your comment forms.

Remember, you want to recognize spam. CAPTCHAs and math trickery doesn’t do that. Akismet does. Spam Karma does. Bad Behavior sorta does.

I get an idea that I want to put into a comment and I scroll down to the comment form and automatically fill out name, email, URL, while processing what I want to say in the comment. Now it asks me to add 6 and 8. Umm, let’s see, what’s 6 and 8. Ah, 14. Okay, now…what was I going to ask or say?

For many people, the process of switching between editorial and mathematical thinking can be enough to stop the mental processes.

And any decent spam bot can break the math quiz, as can all those human comment spammers being paid $5 a day in third world countries as well as the intellectual but stupid folks who comment spam anyway, just because they like the link juice.