The John D. and Catherine T. MacArthur Foundation has named Carnegie Mellon University's Luis von Ahn as one of 25 new MacArthur Fellows for 2006.

Von Ahn, assistant professor of computer science, received a phone call Sept. 12 notifying him that he would be among the latest recipients of the so-called "genius grants," which provide $500,000 in no-strings-attached support over five years.

"Our call comes as a complete surprise and offers the new Fellows the gift of time and an unfettered opportunity to reflect, explore and create," said Jonathan Fanton, president of the MacArthur Foundation. The foundation began the program in 1981; to date, it has named 732 Fellows, ranging in age from 18 to 82 at the time of their selection.Von Ahn has no specific plans yet for his sudden windfall. "Had I won the lottery, I probably would have brought a bigger house," he said. "But I think this money is meant for something more than that."

Recipients of the grants are selected through a process in which hundreds of anonymous nominators identify potential Fellows and a 12-member selection committee, also anonymous, narrows the field and makes recommendations to the foundation's board of directors.Only a select few Pittsburghers have previously been named MacArthur Fellows. They include Christopher Beard, curator of vertebrate paleontology at the Carnegie Museum of Natural History, and William Strickland, arts educator and founder of the Manchester Craftsmen's Guild.

Though the fellowships are popularly known as genius grants, the MacArthur Foundation doesn't describe the recipients as geniuses. In fact, officials contend that the word "genius," with its connotation of intellectual prowess, doesn't adequately describe the Fellows. "The people we seek to support," the foundation's Web site explains, "express many other important qualities: ability to transcend traditional boundaries, willingness to take risks, persistence in the face of personal and conceptual obstacles, capacity to synthesize disparate ideas and approaches."

The foundation cited von Ahn- at 27, the youngest of this year's Fellows- for his work "at the intersection of cryptography, artificial intelligence and natural intelligence to address problems of profound theoretical and practical importance." Specifically, the foundation noted his work in the subdiscipline of cryptography known as steganography, for his role in developing the CAPTCHA tests for determining which Web site visitors are human and which are computers, and for developing online games that harness human wits to solve problems that computers cannot.

"While devising a range of imaginative and broadly applicable security solutions and other interactive systems, von Ahn is tackling every more challenging questions at the frontiers of computer science," a foundation news release stated.

"I am thrilled that Luis von Ahn has been chosen as a MacArthur Fellow," said Jeannette Wing, head of the Computer Science Department. "The MacArthur Foundation seeks to recognize highly creative individuals whose contributions benefit society. Luis is the epitome of such a person.

"Luis's innovations are not just fun tests like CAPTCHAs or fun games like the ESP Game; they solve real-world problems with immediate tangible impact. This honor is wonderful for Luis professionally and wonderful for Carnegie Mellon," she said.

A native of Guatemala, von Ahn received his bachelor's degree in mathematics from Duke University in 2000 and his master's degree and PhD in computer science at Carnegie Mellon in 2003 and 2005. He was a post-doctoral fellow at the Center for Algorithm Adaptation Dissemination and Integration, or ALADDIN, before joining the Computer Science Department faculty this summer.

This year's MacArthur Fellows include D. Holmes Morton, a pediatrician and geneticist who gave up an academic career to operate a clinic for the Amish in Lancaster County, where he studies rare genetic diseases. Another Pennsylvania recipient is John A. Rich, a professor of health management and policy at Drexel University, who is devising ways to provide medical care, education and social services for African-American men in urban settings.

Others include: naturalist author/illustrator David Carroll of Warner, N.H.; jazz violinist Regina Carter of New York City; comparative neurobiologist Kenneth Catania of Vanderbilt University; tropical forester Lisa Curran of Yale University; developmental biologist Kevin Eggan of Harvard University; technologist James Fruchterman of Palo Alto, Calif.; surgeon/author Atul Gawande of Harvard Medical School; bioengineer Linda Griffith of MIT; pharmaceutical entrepreneur Victoria Hale of San Francisco; and narrative journalist Adrian LeBlanc of New York City.

Also: author/illustrator David Macaulay of Norwich, Vt.; sculptor Josiah McElheny of New York City; social psychologist Jennifer Richeson of Northwestern University; playwright Sarah Ruhl of New York City; short story writer George Saunders of Syracuse University; artist Anna Schuleit of New York City; painter Shahzia Sikander of New York City; mathematician Terence Tao of UCLA; aviation engineer Claire Tomlin of Stanford University; deep-sea explorer Edith Widder of Ft. Pierce, Fla.; cosmologist Matias Zaldarriaga of Harvard University and composer John Zorn of New York City.

For more information, visit the MacArthur Foundation Web site, www.macfound.org