These lacunae in computers’ abilities would be of interest only to computer scientists, except that many individuals and companies are finding it harder to locate and organise the swelling mass of information that our digital civilization creates.

The problem has prompted a spooky, but elegant, business idea: why not use the Web to create marketplaces of willing human beings who will perform the tasks that computers cannot? Jeff Bezos, the chief executive of Amazon.com, has created Amazon Mechanical Turk, an online service involving human workers, and he has also personally invested in a human-assisted search company called ChaCha. Bezos describes the phenomenon very prettily, calling it “artificial artificial intelligence.”

“Normally, a human makes a request of a computer, and the computer does the computation of the task,” he said. “But artificial artificial intelligences like Mechanical Turk invert all that. The computer has a task that is easy for a human but extraordinarily hard for the computer. So instead of calling a computer service to perform the function, it calls a human.”

Mechanical Turk began life as a service that Amazon itself needed. (The name recalls a famous 18th-century hoax, where what seemed to be a chess-playing automaton really concealed a human chess master.) Amazon had millions of Web pages that described individual products, but it wanted to weed out the duplicate pages. Software could help, but algorithmically eliminating all the duplicates was impossible, according to Bezos. So the company began to develop a Web site where people would look at product pages and be paid a few cents for every duplicate page they correctly identified.

Bezos figured that what had been useful to Amazon would be valuable to other businesses, too. The company opened Mechanical Turk as a public site in November 2005. Today, there are more than 1,00,000 “Turk Workers” in more than 100 countries who earn micropayments in exchange for completing a wide range of quick tasks called , human intelligence tasks (HITs), for various companies.

Harnessing the collective wisdom of crowds isn’t new. It is employed by many of the “Web 2.0” social networks like Digg and Del.icio.us, which rely on human readers to select the most worthwhile items on the Web to read. But creating marketplaces of mercenary intelligences is genuinely novel.

PriceGrabber.com, a comparison shopping site, uses Mechanical Turk to match images to the product pages. “Harnessing the power of this enormous, decentralized work force allows us to obtain images for a wide variety of items in a fraction of the time it would have taken to do it ourselves,” said Sagar M. Jethani, PriceGrabber’s director of content development and community.

Mechanical Turk’s customers are corporations. Amazon makes money from Mechanical Turk by charging companies 10 per cent of the price of a successfully completed HIT. For simple HITs that cost less than 1 cent, Amazon charges half a cent.

—JASON PONTIN