Human or Computer? Take This Test

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.''

In October Dr. Blum got his wish. Dr. Malik of Berkeley and Greg Mori, a student, devised a computer program that could crack Gimpy -- both the simple version used by Yahoo and the harder one on Captcha's Web site.

Since its inception two years ago, the Captcha effort has been building. Several research teams have joined the Captcha effort, trying to make and break Captchas and even using the ideas behind Captchas for new lines of research.

Researchers at the Palo Alto Research Center modified a program used for scanning text to create a program that could solve certain types of Yahoo-Gimpy puzzles, says Dr. Henry Baird, who was in charge of that effort. The group is also developing a new text-based Captcha called Baffletext that it hopes to license to e-commerce sites.

Inspired by the themes behind Captchas, Dr. Doug Tygar, a professor of computer science at Berkeley, and his student Monica Chew are developing alternatives to passwords that are tailored to human skills. Humans have trouble remembering long, random strings of characters, yet they excel at remembering faces and objects, noted Dr. Tygar.

Dr. Malik said he first became interested in the effort after attending a Captcha conference at the Palo Alto center in January. After he and his former student Dr. Serge Belongie, now at the University of California at San Diego, developed a new object recognition technique modeled to have some of the properties of human vision, Dr. Malik decided that Captchas were ideal for testing their method.

The Yahoo-Gimpy cracking program, written by Mr. Mori, takes a version of the easy Gimpy, a distorted word displayed in a cluttered background, and finds some points along the boundary of each letter, using standard techniques of computer vision theory.

Then, applying the Malik-Belongie method, it makes a radial chart for each point indicating where the other boundary points are in relation to it. The charts of boundary points for that letter are compared with the charts of boundary points for all 26 possible letters. The closest match is usually the correct answer.

Using various tricks to make it run faster, the program can crack an easy Gimpy puzzle in a few seconds, and it gets the right answer over 80 percent of the time.

For the harder version of Gimpy, the researchers devised a program that examines entire words instead of individual letters, so its performance is in minutes rather than seconds, and it gets the puzzle right only about a third of the time. Still, the program will need on average only three tries to get the right answer.

Dr. Malik and Mr. Mori are exploring ways of improving the performance of their program on Gimpy that will also improve their general technique of recognizing objects in a cluttered background.

''We want to keep working on this in a principled way so we can use the same technique on an outdoor scene with buildings, trees and cars,'' Dr. Malik said.

The general technique, he said, will have many practical applications, like automated recognition of military targets or detection of trademark infringements on the Internet.

Meanwhile, Yahoo will have to install a new Captcha that is resistant to Dr. Mori's program. This task will fall to Dr. Manber's successor, since Dr. Manber moved to a new position last month as chief algorithms officer for Amazon.com. There, he said, he plans to continue his collaborations with academic researchers.

''I'd love to foster more cooperation between industry and academica,'' he said. ''It's great for everybody.''

Bits Blog: Drawing the Line on Altering Human Minds

Solar-Powered Plane Faces the Human Factor

The solution, they say, is more technology.

Solar Impulse stands out among airplanes partly because its range is limited not by fuel but the stamina of the pilot.

The single-seat airplane’s cabin is unpressurized, so the pilot must wear an oxygen mask. It has no bathroom. With a grand total of 40 horsepower, the average cruising speed is 38 knots, or about 44 miles an hour, so progress is slow. Even if a pilot can tolerate 26 hours in the tiny cockpit — the record so far — an oceanic flight is hard to imagine.

“The seat is like a really bad economy seat on an airliner,” said Gregory Blatt, a managing director of the company, which is based in Lausanne, Switzerland. “The next version will be like a good business-class seat.”

That version, which is supposed to be able to fly five or six days at a time, will have a bigger seat, a cabin large enough to move around in, some plumbing and various other upgrades, like an autopilot. But that means a heavier plane that will require more efficient solar cells, electric motors and other improvements.

A Solar Impulse plane, an eye-catching proof-of-concept vehicle, arrived at the Smithsonian Air & Space Museum’s branch at Dulles Airport over the weekend from St. Louis, part of a photovoltaic barnstorming tour. The plane’s designers say the successor airplane, already under development, needs crucial but incremental improvements.

The four motors on the existing model, for example, are 90 percent efficient in turning current into torque, far better than most motors on the ground. But the new ones are 94 percent efficient, said Bertrand Piccard, chairman of the company and one of the two pilots. (Some inefficiency is desirable, because the energy that does not go into turning the propellers instead becomes heat, which is needed to keep the motors and the batteries warm at cruising altitude, around 29,000 feet. The batteries are tucked into the pods under the wings that hold the motors.)

The solar cells on the wings and the horizontal tail, from the SunPower Corporation of San Jose, Calif., are about 22.7 percent efficient, Mr. Blatt said. New cells will be better than that, he added. The existing plane carries 11,628 solar cells.

The existing cells are of a type already in use, but they are used in Solar Impulse in a new way. They do not cover the skin of the wing, but rather are the skin of the wing: thin monocrystalline cells, given a slight bend so the wing creates lift. The wingspan is huge, about the same as a Boeing 747. The whole plane weighs only about 3,500 pounds, so what aeronautical engineers call “wing loading,” or force of the air on the wing, is low.

The lithium-polymer batteries, from Kokam, a Korean company, are also a commercial product.

Ernest Moniz, the Energy secretary, who visited the hangar on Monday to look at the plane, praised it not only for using new technology but for integrating it into a useful package.

“Energy efficiency and system integration are enormously important areas,” he said. Efficiency is crucial because the propulsion system is not quite as big as one on a large motorcycle.

One innovation is the foam used in the structure of the plane, which has unusually small pores. Dan Reicher, a former assistant secretary of energy now at Stanford Law School, said that the foam had already found its way into refrigerators, because it is a better insulator.

The plane is scheduled to end its tour at Kennedy International Airport in New York early next month, depending on weather. Because it is so light and has such a large wingspan, it is vulnerable to gusts at low altitude, said André Borschberg, the company chief executive and the other pilot.

As a result, it takes off and lands at night, when there is no solar warming of the earth, which produces wind. And landing is an elaborate problem. Its main landing gear is a single wheel, and to keep its wing tips from scraping on the ground, the team deploys two people on electric bicycles to sweep in and hold the wings up as the plane touches down.

With a touchdown speed of 26 knots, about 30 m.p.h., this is not difficult. But it requires a runway without much other traffic, or it becomes like riding a bicycle on an interstate highway. At Kennedy, the plan is to circle at low altitude near the runway until there is a big gap in the traffic, Mr. Piccard said.

Obama to Unveil Initiative to Map the Human Brain

A senior administration scientist compared the new initiative to the Human Genome Project, in that it is directed at a problem that has seemed insoluble up to now: the recording and mapping of brain circuits in action in an effort to “show how millions of brain cells interact.”

It is different, however, in that it has, as yet, no clearly defined goals or endpoint. Coming up with those goals will be up to the scientists involved and may take more than year.

The effort will require the development of new tools not yet available to neuroscientists and, eventually, perhaps lead to progress in treating diseases like Alzheimer’s and epilepsy and traumatic brain injury. It will involve both government agencies and private institutions.

The initiative, which scientists involved in promoting the idea have been calling the Brain Activity Map project, will officially be known as Brain Research Through Advancing Innovative Neurotechnologies, or Brain for short; it has been designated a grand challenge of the 21st century by the Obama administration.

Three government agencies will be involved: the National Institutes of Health, the Defense Advanced Research Projects Agency and the National Science Foundation. A working group at the N.I.H., described by the officials as a “dream team,” and led by Cori Bargmann of Rockefeller University and William Newsome of Stanford University, will be charged with coming up with a plan, a time frame, specific goals and cost estimates for future budgets.

The initiative exists as part of a vast landscape of neuroscience research supported by billions of dollars in federal money. But Dr. Newsome said that he thought a small amount of money applied in the right way could nudge neuroscience in a new direction.

“The goal here is a whole new playing field, whole new ways of thinking,” he said. “We are really out to catalyze a paradigm shift.”

Brain researchers can now insert wires in the brain of animals, or sometimes human beings, to record the electrical activity of brain cells called neurons, as they communicate with each other. But, Dr. Newsome said, they can record at most hundreds at a time.

New technology would need to be developed to record thousands or hundreds of thousands of neurons at once. And, Dr. Newsome said, new theoretical approaches, new mathematics and new computer science are all needed to deal with the amount of data that will be garnered.

As part of the initiative, the president will require a study of the ethical implications of these sorts of advances in neuroscience.

While news of the announcement has been greeted with enthusiasm by many researchers in fields as diverse as neuroscience, nanotechnology and computer science, there are skeptics.

“The underlying assumptions about ‘mapping the entire brain’ are very controversial,” said Donald Stein, a neuroscientist at Emory University in Atlanta. He said changes in brain chemistry were “not likely to be able to be imaged by the current technologies that these people are proposing.”

Emphasizing the development of technologies first, he said, is not a good approach. “I think the monies could be better spent by first figuring out what needs to be measured and then figuring out the most appropriate means to measure them.” he said. “In my mind, the technology ought to follow the concepts rather than the other way around.”

However, supporters of the initiative argued that it could have a similar impact as the Sputnik satellite had in the 1950s, when the United States started a significant nationwide effort to invest in science and technology.

“This is a different time,” said Michael Roukes, a physicist at the California Institute of Technology. “It makes sense to have a brain activity map now because the maturation of an array of nanotechnologies can be brought to bear on the problem.”

While the dollar amount committed by the Obama administration does not match the level of spending on the Human Genome Project, scientists said that whatever was spent on the brain initiative would have a significant multiplier effect. The Salk Institute in La Jolla, Calif., is contributing money, said Terrence J. Sejnowski, head of the institute’s computational biology laboratory, adding that the project would have an impact at the neighboring University of California, San Diego, campus.

“One concrete example is that the chancellor has gotten excited about this and has decided that it is a great thing to invest in,” Dr. Sejnowski said. “That means hiring new faculty and creating new space.”

The project grew out of an interdisciplinary meeting of neuroscientists and nanoscientists in London in September 2011. Miyoung Chun, a molecular biologist who is vice president of scientific programs at the Kavli Foundation, had organized the conference. Her foundation, she said, supports the idea that the next big scientific discoveries will come from interdisciplinary research.

“Federal funding is scarce these days, and I realized we need inspiring projects that can awake everyone’s imagination,” she said. “It occurred to me that this is a very inspiring idea.”

This article has been revised to reflect the following correction:

Correction: April 4, 2013

An article on Tuesday about a research initiative to invent and refine technologies to understand the human brain misstated the relationship between the Salk Institute and the University of California, San Diego. The Salk Institute, which is giving money to the research initiative, is an independent institute; it is not based at, or part of, the university.