The New York Times The New York Times Science December 10, 2002  

Home
Job Market
Real Estate
Automobiles
News
International
National
Washington
Business
Technology
Science
- Earth Science
- Life Science
- Physical Science
- Social Science
- Space
- Columns
Health
Sports
New York Region
Education
Weather
Obituaries
NYT Front Page
Corrections
Opinion
Editorials/Op-Ed
Readers' Opinions


Features
Arts
Books
Movies
Travel
Dining & Wine
Home & Garden
Fashion & Style
New York Today
Crossword/Games
Cartoons
Magazine
Week in Review
Multimedia/Photos
College
Learning Network
Services
Archive
Classifieds
Book a Trip
Personals
Theater Tickets
NYT Store
NYT Mobile
E-Cards & More
About NYTDigital
Jobs at NYTDigital
Online Media Kit
Our Advertisers
Member_Center
Your Profile
E-Mail Preferences
News Tracker
Premium Account
Site Help
Privacy Policy
Newspaper
Home Delivery
Customer Service
Electronic Edition
Media Kit
Community Affairs
Text Version
Go to Advanced Search/ArchiveGo to Advanced Search/ArchiveSymbol Lookup
Search Optionsdivide
go to Member Center Log Out
  Welcome, annoying

Human or Computer? Take This Test

By SARA ROBINSON

As chief scientist of the Internet portal Yahoo, Dr. Udi Manber had a profound problem: how to differentiate human intelligence from that of a machine.

His concern was more than academic. Rogue computer programs masquerading as teenagers were infiltrating Yahoo chat rooms, collecting personal information or posting links to Web sites promoting company products. Spam companies were creating havoc by writing programs that swiftly registered for hundreds of free Yahoo e-mail accounts then used them for bulk mailings.

Advertisement

A floor lamp that spreads sunshine all over a room

Scientists adapt NASA technology to create "smart bed" sleep surface

With this Flashlight - batteries are not included...or needed!

Watch your favorite movie anywhere you go

It’s time to put all of your photos onto your computer

Atomic accuracy in any U.S. time zone

A portable hard drive that fits in your pocket?

Best pick for Holiday digital camera

Natural de-icer means you’ll have to shovel less this winter




"What we needed," said Dr. Manber, "was a simple way of telling a human user from a computer program."

So, in a September 2000 conference call, Dr. Manber discussed the problem with a group of computer science researchers at Carnegie Mellon University. The result was a long-term project that is just now beginning to bear fruit.

The roots of Dr. Manber's philosophical conundrum lay in a paper written 50 years earlier by the mathematician Dr. Alan Turing, who imagined a game in which a human interrogator was connected electronically to a human and a computer in the next room. The interrogator's task was to pose a series of questions that determined which of the other participants was the human. The human helped him, while the computer did its best to thwart him.

Dr. Turing suggested that a machine could be said to think if the human interrogator could not distinguish it from the other human. He went on to predict that by 2000, computers would be able to fool the average interrogator over five minutes of questioning at least 30 percent of the time.

Although the Turing test, as it is now called, spawned a vibrant field of research known as artificial intelligence, his prediction has proved false. Today's computers are capable of feats Dr. Turing never imagined, yet in many simple tasks, a typical 5-year-old can outperform the most powerful computers.

Indeed, the abilities that require much of what is usually described as intelligence, like medical diagnosis or playing chess, have proved far easier for computers than seemingly simpler abilities: those requiring vision, hearing, language or motor control.

"Abilities like vision are the result of billions of years of evolution and difficult for us to understand by introspection, whereas abilities like multiplying two numbers are things we were explicitly taught and can readily express in a computer program," said Dr. Jitendra Malik, a professor specializing in computer vision at the University of California at Berkeley.

Dr. Manuel Blum, a professor of computer science at Carnegie Mellon who took part in the Yahoo conference, realized that the failures of artificial intelligence might provide exactly the solution Yahoo needed. Why not devise a new sort of Turing test, he suggested, that would be simple for humans but would baffle sophisticated computer programs.

Dr. Manber liked the idea, so with his Ph.D. student Luis von Ahn and others Dr. Blum devised a collection of cognitive puzzles based on the challenging problems of artificial intelligence. The puzzles have the property that computers can generate and grade the tests even though they cannot pass them. The researchers decided to call their puzzles Captchas, an acronym for Completely Automated Public Turing Test to Tell Computers and Humans Apart (on the Web at www.captcha.net).

One puzzle, called Gimpy, consists of a display of seven distorted, overlapping words chosen at random from a dictionary of simple words. Solving the puzzle requires identifying three of the seven words and typing them into the box provided. The Carnegie Mellon group also created a simplified version of Gimpy — a single distorted word displayed against a complicated background. It is now part of Yahoo's registration process.

Another Captcha, called Sounds, consists of a distorted, computer-generated sound clip containing a word or sequence of numbers. To solve the puzzle, a user must listen to the clip and type the word or numbers into the box provided.

The idea of using puzzles to prevent automated registrations was not new. Other e-commerce sites, including the AltaVista search engine and eBay's PayPal service, were experiencing problems like Yahoo's and independently came up with Captcha-like puzzles. Through its acquisitions, Hewlett-Packard holds a patent on text-based Captchas.

Still, researchers credit Dr. Blum for the breadth of his vision. Dr. Blum "did a great thing by recognizing that this problem is much more than solving a nuisance for Yahoo and AltaVista," said Dr. Andrei Broder, who helped develop the AltaVista puzzle and is now at I.B.M.

As a cryptographer, Dr. Blum was familiar with the constant efforts of cryptographic researchers to advance the field by cracking codes to discover their weaknesses.

He hoped to start a similar dynamic for Captchas, spurring researchers to try to create better Captchas while building computer programs that crack existing ones.

"Captchas are useful for companies like Yahoo, but if they're broken it's even more useful for researchers," Dr. Blum said. "It's like there are two lollipops and no matter what you get one of them."

Continued
1 | 2 | Next>>




Technology Briefing | Internet: Starbucks Expands Web Network Service  (August 22, 2002)  $

Technology Briefing | Internet: Bioscrypt Excels In Fingerprint Technology Tests  (August 16, 2002) 

Officials Link Foreign Web Sites to Cheating on Graduate Admission Exams  (August 8, 2002)  $

BUSINESS TRAVEL; MEMO PAD  (July 16, 2002)  $

Find more results for Computers and the Internet and Tests and Testing .



Doing research? Search the archive for more than 500,000 articles:




E-Mail This Article
Printer-Friendly Format
Most E-Mailed Articles
Reprints
Single-Page View

Wake up to the world with home delivery of The New York Times newspaper.
Click Here for 50% off.


Home | Back to Science | Search | Corrections | Help | Back to Top


Copyright The New York Times Company | Permissions | Privacy Policy
E-Mail This Article
Printer-Friendly Format
Most E-Mailed Articles
Reprints
Single-Page View


Justin Merriman for The New York Times
Man or machine? That is the question Dr. Manuel Blum has tackled by devising a series of mental puzzles. Dr. Blum, by the way, is real.



Try the tests online at The Captcha Project



Topics

 Alerts
Computers and the Internet
Tests and Testing
Yahoo! Incorporated
Create Your Own | Manage Alerts
Take a Tour
Sign Up for Newsletters





Justin Merriman for The New York Times
Manuel Blum, left, a Carnegie Mellon professor, and Luis von Ahn, a Ph.D. student, devised ways of preventing automated registrations at Web sites.






An early computer, the "mechanical mind" developed at MIT, 1927.

Price: $195. Learn More.








Spotlight on...

Westchester Homes
Search for homes in Scarsdale, Ardsley, Tarrytown...

New Jersey Waterfront
Search for homes in Hoboken, Jersey City...


Search Other Areas









Search by Zip Code:

Sign up for E-Mail Alerts,
Luxury & Vacation Homes
Hamptons
Florida
Wine Country
Western States
More...

Mortgage & Moving Services