In the four decades since the dawn of the nuclear age, Americans have shifted dramatically from a belief that nuclear arms serve the cause of peace to an overwhelmingly opposite view -- one that is fraught with misinformation and confusion but which shows solid consensus on certain questions.

These are among the findings of a survey released yesterday by the Public Agenda Foundation, a nonpartisan research organization headed by pollster Daniel Yankelovich.

The 91-page report, "Voter Options on Nuclear Arms Policy," was designed to provide a basis for public dialogue on a key issue in the battle for the presidency, survey officials said. Copies were sent to the presidential candidates and to members of Congress.

In the early '50s, the survey noted, Americans said 2 to 1 that nuclear arms reduced the danger of war.

At the same time that nuclear experts have grown less anxious about the subject, the level of concern among ordinary Americans has increased "massively and intensively," Yankelovich said.

The survey showed, for example, that half of all people under 30 believe that "all-out nuclear war is likely to occur within the next 10 years."

Another huge gap between public understanding and the way the experts perceive things is reflected in the survey's findings on a key policy question. "Virtually all Americans -- 81 percent -- mistakenly believe it is our policy to use nuclear weapons if, and only if, the Soviets attack the United States first with nuclear weapons," the survey found.

"So there is almost universal misunderstanding of what NATO policy really is," Yankelovich said, noting that official policy is to reserve the option for first use of nuclear weapons.

Among findings that show significant consensus among the public:

*Eighty-nine percent believe there can be no winner in an all-out nuclear war -- that both the U.S. and the Soviet Union would be destroyed.

*Seventy-six percent reject the claim that it is a "wild exaggeration" that all life would be destroyed in a nuclear war.

*Ninety percent believe that the Soviets secretly built up their own military strength during detente.

*Seventy-six percent believe that the U.S. shares the blame for bad relations with the Soviets.

The findings also identified areas in which Americans send mixed signals. While 57 percent favor development of new weapons to prevent the nation from losing the arms race, 50 percent say the country would be safer if it shifted its emphasis from military effort to negotiations.

Forty-six percent say the U.S. should use military force if needed to prevent worldwide communist expansion, but 53 percent say this nation would be safer if it stopped trying to prevent the spread of communism.

Seventy-four percent would refuse to sign an arms agreement unless the Soviets agreed to on-site inspection, but 56 percent say they would sign even if verification couldn't be guaranteed.

The survey, published jointly with the Center for Foreign Policy Development of Brown University, was based on group discussions with "typical citizens" around the country, data from various polls and a random survey done in May.