Catching up on my reading today I noticed this entry over at SitePoint:

http://www.sitepoint.com/blogs/2009/05/10/googles-new-capcha-the-only-way-is-up/

Seems an interesting new take on CAPTCHAs. I've downloaded the white paper referenced in the article, and I'll probably read it while I wait for my doctor's appointment later today.
I like that from the outset they acknowledge that its still a problem for visually impaired users, and that the CAPTCHA farms are a different class of problem.
I'll still find whatever alternatives there are before I resort to CAPTCHAs myself, but its worth keeping up. Your thoughts?

There's really no method of using a CAPTCHA (regardless of the method - image rotation, angled characters, distorted foregrounds, etc) that doesn't pose a large problem for image impaired individuals. If you provide an audio option, then the spammers will use some sort of voice recognition software and automate that also.
That said, the image rotation (for people without vertigo and other horizon-related impairments) is probably the cleanest-looking CAPTCHA that I've seen.
Speaking of CAPTCHA techniques, I just reviewed this article. While it has nothing to do with CAPTCHA, per se, it had the following CAPTCHA at the bottom - the comments on the image are mine:

Image and audio captcha's should be avoided at all costs in my opinion. A much better captcha approach is asking a simple understandable question that has an answer which one can easily enter.
For example: which of the following words is a type of fruit: bowling ball, dog, banana : [type answer]
Or even more simple: how much is one plus two ? : [type answer] It's very easy to create a list of hundreds and hundreds of questions with multiple correct answers (as 3 and three are both correct answers to the example question).
As long as the CAPTCHA bots aren't capable of understanding semantecs they won't be able to answer these questions while (virtually) any human being capable of using a computer is able to.
I've seen this form of captcha on several Wordpress blogs already, with questions such as "What's my first name?" or "What is this site about?" (where the answer photos, photography and several variations of that are valid). Works great, also for the visually impaired as screenreaders are able to read those questions without any problem.

Originally posted by MarcelG
For example: which of the following words is a type of fruit: bowling ball, dog, banana : [type answer]
Or even more simple: how much is one plus two ? : [type answer]

I have to disagree in part because it's not only this, specially if this is implemented to an international website, I know engligh, pretty much and I sometimes cross websites with weird questions, specially if you don't know English that well, take a look at my post in tenderapp.com (a really good support system)

they come up with this:


what a non-english person even with engligh knowledge will have some degree of difficult.
it is a hard topic, but I would take your idea and as I said there, add a reload question, so we can find a easier one quickly as well add several question in native language (seeing the browser language or giving a dropdown to choose it's own language)...
at least it my idea and I like to share

I'm perfectly fine with image captchas, didnt have any major spam attacks,and had a Golden Spider Award here in 2008 from the category of "Accesibility" from Visual/Hearing Impaired... So... /shrug

Accessibility arguments, etc. aside; all you're really doing with CAPTCHAs is inconveniencing & frustrating legitimate users by making them jump through extra hoops. As I always say, never do anything online that you wouldn't get away with doing offline; if you force customers to prove that they're real people before letting them into your shop (just take a moment to think about how ridiculous that statement sounds!), you're not going to be in business very long.
Also, remember that, if they're that determined - and history has proven that they are - spammers & crackers are always going to find a way to circumvent whatever measures you implement in an attempt to thwart them. There is absolutely no substitute for human monitoring and intervention when it comes to spam.

Creative simplicity helps regarding CAPTCHA questions. What is the opposite direction of "UP"" ? """"""Down": ? American flag colors are "Red", "White" and: ? The opposite direction of "east" is: ? What color is the sun: ? The sky: ? Grass: ?
Anyone can come into my shop. It's when they want to use a credit card that I want to see some ID.