Dr. Douglas Vakoch is drafting messages in case of signals from response to communication from extraterrestrial intelligence. He wants any message to be altruistic.

That would be Dr. Douglas Vakoch, aspiring psychotherapist, philosopher, self-described exo-semiotician, and resident psychologist at the SETI Institute in Mountain View, Calif., which is dedicated to the search for extraterrestrial intelligence. It is his job to come with ideas for a response in case any searchers ever discern, amid the crackle and hiss of radio waves from outer space, the equivalent of a "Hi there — what's your name?"

It was the search for a suitable answer that found Dr. Vakoch, standing on a lonely sidewalk here late one chilly evening looking for the back way into a brick building. He was in town to attend and discuss a new play about an outer space organism that turns people's skins green, and to give a talk about the problems of composing interstellar interspecies messages.

In between, he was hoping to squeeze in a visit to a meeting of Alcoholics Anonymous, a homework assignment for getting a license to practice psychotherapy in California, his home state, but the building was locked. Of course, as a SETI researcher, Dr. Vakoch knows that frustration is part of the process.

"The initial message we send, if we ever do send any, would create the first impression for what would be a dialogue that would be occurring over many generations," Dr. Vakoch said.

In the interest of making a good impression, and perhaps counteracting the burble of "Survivor," automobile ads and political news spreading outward through the galaxy on radio and television waves, Dr. Vakoch is using a grant from the John Templeton Foundation to devise a message that encodes the notion of altruism, which many biologists and humanists would like to think is a pillar of any civilization.

It is an effort, he says, that will have value even if there is nothing but silence from the heavens. "By thinking about who we would want to represent ourselves, we're forced to reflect in a different way than we usually do about what our deepest values are," Dr. Vakoch said.

"And by attempting to put some of the ideas and values most important to us in an abstract universal language, we're forced to clarify what we mean by those things."

The search for extraterrestrial intelligence has proceeded in fits and starts ever since 1959, when two Cornell University physicists, Dr. Philip Morrison and Dr. Giuseppe Cocconi, suggested that extraterrestrial civilizations would find it easier and cheaper to reach across the galaxy with radio waves than to visit in person.

The SETI Institute is now halfway through a survey of 1,000 nearby sunlike stars, Project Phoenix, so named because it rose from the ashes of a NASA-sponsored program that was canceled in 1993. The institute's astronomers are already laying plans for a new search with new radio telescopes, which will extend the survey to some 30,000 stars. By comparison, there are roughly 400 billion stars in Earth's own Milky Way galaxy, but the technology behind a search increases with each improvement in computer chip technology. "We are more and more capable of detecting something if anything is out there," Dr. Vakoch said.

In April 1989, the trustees of the International Academy of Astronautics, an organization of distinguished rocket scientists, approved a protocol outlining how scientists should check out any signal from outer space and what they should tell the world about it, declaring finally, "No response to a signal or other evidence of extraterrestrial intelligence should be sent until appropriate international consultations have taken place."

Several organizations, including the International Institute of Space Law and the International Astronomical Union, have approved it, but Dr. Vakoch said, the protocol is not legally binding. Dr. Jill Tarter, who directs the SETI Institute's observing program and is Dr. Vakoch's boss, has briefed the United Nations Committee on the Peaceful Uses of Outer Space on the need to develop a second protocol on how and whether to reply to a signal. Developing a consensus, should the United Nations choose to take up the issue, would be long and hard, noted Dr. Paul Horowitz, a Harvard physics professor and independent SETI researcher. "It's O.K.," he added, ET can wait.

The history of trying to signal other worlds, often using scientific symbols to advertise our own intelligence, is long. In the 19th century, the mathematician Karl Friedrich Gauss suggested burning or otherwise etching giant geometric figures on the surface of Earth as a way of attracting attention from Martians.

In 1974, Dr. Frank Drake, then of the National Radio Astronomy Observatory and now the institute's chairman, beamed a message at a star cluster 25,000 light-years away, a string of bits — or ones and zeroes — that could be assembled into a two-dimensional array, a pictogram, showing the figure of a man, a telescope, the numbers, DNA and the solar system.

More elaborate messages have been included on spacecraft like the Voyagers now headed out of the solar system, including a record with sights and sounds of Earth, including music from Bach to Chuck Berry.

Dr. Vakoch is critical of the scientific orientation of many message schemes. "Just because we're focused on a scientific description of ourselves, that doesn't mean that they will automatically take that as a starting point for a conversation," he said.

Presumably, ET already knows about prime numbers and the laws of physics. "The interesting thing is, `Oh, that's a quirky little biology — I haven't seen a class K-17 do something like that before,' or "Oh, look at their strange dyadic interreactions!' " That is, to say, sex.

What in other words, is it like to be human?

Dr. Vakoch, who became interested in interstellar messages as a 15- year-old high school student in Minnesota, said that as a younger man, he often felt unequal to the task of answering that question. And he has been bouncing back and forth between inner space and outer space ever since. As an undergraduate at Carleton College in Minnesota, he studied comparative religion, and then history and philosophy of science at Notre Dame, emerging with a master's degree in 1987.

In between, there was a three-year stint working as a hotel clerk and reading about SETI and sociobiology. Looking, he says, for relevancy and the chance to do something concrete in the world, he then studied psychology at the State University of New York at Stony Brook.

"One benefit of psychotherapy," he explained, "is the opportunity for self-reflection. To be a good psychologist, you need to understand yourself."

His work in psychology and related areas like semiotics, the study of signs and symbols, convinced Dr. Vakoch that interstellar communication might be more difficult than the astronomers and physicists who make up most of the SETI community thought, and than he himself had thought as a high school student under the brilliant bone-chilling night skies back in Minnesota. That was a point he made in his first talk before the SETI community, in Oslo in 1996.

One problem, he pointed out then, is the notion that science can be the basis of communication between disparate species. This implies, he says, that different cultures with different histories and physical forms will all converge on the same scientific description of reality, and that they will have passed through the same stages of scientific development to get there.

It is possible, he argues, that extraterrestrials could invent radio technology — the one indispensable entrance requirement to galactic society — without ever developing the concept of an atom or of a DNA molecule.

Another is the form of the messages themselves, often pictograms of the sort pioneered by Dr. Drake. But even on Earth, different cultures cannot necessarily agree on the meaning of a picture or, for example, how to portray a human being.

"If you look at the swirls on carvings of Maori ceremonial buildings, they're obviously human beings — if you're Maori," he explained. "If you're American, it's a great geometrical pattern."

No message, he explained, could ever be free of ambiguity. As a result, "we have no basis for the belief that any part of the message will be intelligible," he said.

To seasoned SETI scientists who were used to seeing the same faces year after year arguing about magic radio frequencies or about the meaning of the apparent lack of aliens in our vicinity, this was invigorating. "Here's a guy who's not an astronomer, physicist or from any other of the hard sciences, saying, `You guys have blinders on — there's more to communicating with diverse species than you imagined,' " said Dr. Horowitz.

After obtaining his Ph.D. in psychology in 1996 and a three-year postdoctoral fellowship at Vanderbilt, Dr. Vakoch felt ready finally to commit himself to the interstellar trade. He was also known by then in SETI circles and accepted a halftime position at the SETI Institute, which has had a longtime interest in promoting research into the social and cultural aspects of extraterrestrial contact.

In his new perch, Dr. Vakoch performs research on the attitudes of the public toward extraterrestrials, but his main emphasis, with the advent of the Templeton grant, is on message ideas.

One way to get around the ambiguity of pictures, he suggests, is to send messages that portray objects in three-dimensional space, like sculptures that an alien can choose to view from any angle. Sequences of these images could then be assembled in a kind of "interstellar ballet," as Dr. Vakoch calls it, using the vocabulary of dance, gestures and pointing, to teach and convey information.

Dr. Vakoch admits that altruism is a somewhat arbitrary starting point, but a logical one. For one thing, some aspects of altruism lend themselves to mathematical analysis, he explained. The willingness of creatures to risk their lives to protect others from predators, sociobiologists say, can be explained by kin selection — the degree to which the protectors and protected share genes, a concept that can be expressed mathematically.

Another is the notion of reciprocal altruism, in which you pick bugs out of my hair and I give you a banana later. The idea, Dr. Vakoch points out, is crucial to SETI. The radio telescopes used for it are too weak to detect signals that have not been broadcast directly at us. "It seems plausible," he said, "that if other beings are sending a transmission, in a sense they are practicing altruism," perhaps in the hope of getting a message and information back in return someday.

A natural basis for transmitting such concepts exists, he says, in the form of a mathematical language known as Lingua Cosmica, or Lincos, for short, developed in 1960 by the late Dutch mathematician Dr. Hans Freudenthal at Utrecht University. In a 200-page volume, Dr. Freudenthal showed how with a series of simple signals a sender could progress from describing numbers and arithmetic to space, matter and even human beings, at least in terms of bodies of a given mass located in space.

A juiced-up version of Lincos, Dr. Vakoch said, could describe kin selection, or portray beings trading information. "In fact," he said, "I'd suggest we make reference to the proposed exchange of information, if that's what we're doing, to help explain some of our notions of reciprocal altruism."

In the meantime, there is cosmic silence to contend with, which is why Dr. Vakoch wants to get a psychotherapy license. He hopes to practice one or two nights a week, enough to pay the rent on an office and to feel as if he is still part of the human race. "I couldn't justify psychotherapy as fun if it did not feed into work on message content," Dr. Vakoch said. "Time spent here is time not spent on doing message work, but it feeds into creating a more nuanced view of what it means to be human."