A
technology start-up said on Monday that it had come up with software
that worksa human brain in one key way: it can crack CAPTCHAs, the
strings of tilted, squiggly letters that websites employ to make users
"prove you are human," as Yahoo! and others put it.
San
Francisco-based Vicarious developed the algorithm not for any nefarious
purpose and not even to sell, said co-founder D. Scott Phoenix.
Instead,
he said in a phone interview, "We wanted to show we could take the
first step toward a machine that worksa human brain, and that we are the
best place in the world to do artificial intelligence research."
The
company has not submitted a paper describing its methodology to an
academic journal, which makes it difficult for outside experts to
evaluate the claim. Vicarious offers a demonstration of its technology
atshowing its algorithm breaking CAPTCHAsGoogle and eBay
's PayPal, among others, but at least one expert was not impressed.
"CAPTCHAs
have been around since 2000, and since 2003 there have been stories
every six months claiming that computers can break them," said computer
scientist Luis von Ahn of Carnegie Mellon University, a co-developer of
CAPTCHAs and founder of tech start-up reCAPTCHA, which he sold to Google
in 2009. "Even if it happens with letters, CAPTCHAs will use something
else,pictures" that only humans can identify against a distorting
background.
CAPTCHA stands for Completely
Automated Public Turing test to tell Computers and Humans Apart. They
are based on the standard set in 1950 by British mathematician Alan
Turing in 1950: a machine can be deemed intelligent only if its
performance is indistinguishablea person's.
CAPTCHAs
serve that function: in order to sign up for free email, post comments,
buy tickets or other online activities, more than 100,000 websites
require users to prove they are human by deciphering the squiggly
letters, which are often blurred, smeared and cluttered with dots and
lines.
In practice, someone trying to break
CAPTCHAs in order to do what a site is trying to deter - sign up for
umpteen email accounts, for instance - can easily hire someone to
accomplish that. "Most CAPTCHAs now are broken by paying people in
Bangladesh to do it manually," said computer scientist Greg Mori of
Simon Fraser University in British Columbia, an expert on machine
learning and computer vision. "For 50 cents an hour, you can get someone
to break seven per minute."
DIGITIZING BOOKS?
Developing
software to break CAPTCHAs would in theory speed that up exponentially.
Vicarious said its algorithm achieves success rates of 90 to 97 per
cent, depending on the difficulty of the CAPTCHA; a CAPTCHA scheme is
considered broken if a machine can break just 1 per cent of the ones it
generates.
That makes "text-based CAPTCHAs no
longer effective as a Turing test," the company said in a statement,
meaning that CAPTCHAs can no longer be used to tell humanmachine.
That
might be beneficial, experts said. Google's reCAPTCHA uses wordsold
books and other publications that have been optically scanned but are
difficult to digitize because they are so degraded. "If you can actually
solve reCAPTCHAs, you can digitize old books more easily," said Mori.
In addition, the algorithm Vicarious uses to break CAPTCHAs might be deployed more widely.
"If
they've done it, it could improve the reliability of opticalacter
recognitionthat used in banks to scan checks and by the IRS (Internal
Revenue Agency) to read scanned documents," said Karl Groves, an
independent website developer who for years has tracked claims about
breaking CAPTCHAs.
The feat required
relatively tiny amounts of data and computing power, Vicarious said,
instead using algorithms that mimic the perceptual and cognitive
abilities of the human brain.
The company has
described only in general terms what it hopes to use artificial
intelligence for, describing its goals as building a vision system
modeled on the human brain and developing human-level artificial
intelligence based on what it calls a "recursive cortical network," for
applications in robotics, medical image analysis, image and video
search, and other fields.
That has been
sufficient to attract more than $15 million in fundinginvestors
including Facebook co-founder and Vicarious board member Dustin
Moskovitz. In a statement, he said, "We should be careful not to
underestimate the significance of Vicarious crossing this milestone,"
adding that the company is "at the forefront of building the first truly
intelligent machines."
