Elizabeth Weise

USA TODAY

SAN FRANCISCO – Don't be surprised if the next time you try to access a website, instead of asking you to retype an inscrutable series of letters and numbers, you're simply asked to check a box next to this statement:

"I'm not a robot."

It's the latest iteration of an on-going war between spammers and computer scientists. In this round, the scientists won.

Those squiggly, hard-to-read number and letter combinations are called CAPTCHA's.

It stands for "Completely Automated Public Turing test to tell Computers and Humans Apart."

Which is what they do. Computers aren't supposed to be able to read them, while humans easily can. Except that's not really the case anymore.

Testing by researchers at Google found that with advances in artificial intelligence programs, it's now possible for a computer to read even the most complex, distorted text with an accuracy of 99.8%, said Vinay Shet, product manager for Google's new reCAPTCHA project.

But the Google researcher thought, if computers were getting so good are reading squiggly text, perhaps they were getting good at other things as well.

About 18 months ago, Google began working on an advanced risk analysis engine that could figure out just who--or what--was behind an attempt to get through a CAPTCHA screen.

The researchers looked at a host of cues. They included what web site the person had come from, where their mouse went on the screen, how long it moved, how steady it was and other cues Google won't divulge.

In just a few seconds the program could make a good guess about whether "a human or a 'bot" was making the attempt, said Shet.

Which meant no more trying to read half-melted text just to get to what you wanted to see.

The new system doesn't work for all attempts, but for "a significant fraction of users" it means they'll just have to click the 'I'm not a robot' box and be on their merry way.

Google, which bought CAPTCHA in 2009, has now deployed the new technology on several websites, including Snapchat, Wordpress and Humble Bundle.

"In the last week more than 60% of WordPress traffic and more than 80% of Humble Bundle's traffic has encountered the NoCAPTCHA experience," Shet wrote on a blog published Wednesday.

The technology is free and Google is making it available to anyone who'd like to use it.

Google is also rolling out a more mobile-friendly CAPTCHA for those working on cell phones. In this, instead of typing in text, users are presented with a picture of something, say a kitten, and then nine other images. They have to tap each image that is also of a kitten.

"For example, in the last week, more than 60% of WordPress' traffic and more than 80% of Humble Bundle's traffic on reCAPTCHA encountered the No CAPTCHA experience—users got to these sites faster," said Shet.