Intelligent Captcha system

[esllou]

I am looking at a more intelligent, intuitive captcha system to use on my community site in an attempt to cut down on spam.

I was on a site the other day and the captcha asked me "what color is an orange?", which I liked but I need something for a multi-national community.

So, I was thinking about numbers.

2 + 2 =?
1, 2, 3,?, 5
How many stars are there? ******

has anyone seen this type of numeral based system being used. It goes beyond OCR because even if spiders, as I've heard, are getting better at character recognition, they will still need to "solve" the captcha.

Any thoughts on the workability of this?

[jimbeetle]

There are a couple of them out there for different CMS flavors. I'm having a bit of a problem wrapping my head around how effective they might be. I guess I'm assuming that if they can train bots to use OCR to read image captures it would be even easier to train them to read and answer a simple text string such as "Spam protection: Sum of 4 + 10?"

[esllou]

OCR is one thing, being able to actually process what is written is still far beyond computers. What do you teach them to understand?

2 and 2
2 plus 2
sum of 2 and 2
2 + 2
and so on...

the key is using a captcha response that isn't in the original image - and numbers seems the best way of doing that.

[chance1376]

Postnuke recently implemented this system for registration and it works great. With the way it is set up you can make up any question and any answer. We have a site that has international visitors but those who sign up can speak english really well. So I am not sure how great of an international test that is.