American Express Co. Chairman James D. Robinson III has warned that in an era of "information overload" and dwindling time or patience by the public to absorb it all, the United States is "becoming a nation of fast-fact junkies."

Robinson criticized business leaders as well as the mass communications media for helping to bring the nation to "a dangerous point of divergence," with a society that is fragmented, disillousioned and focused on "an ugly, me-first attitude."

The American Express chief executive issued his warning Monday in an address to the American Advertising Federation convention here, which began on Saturday. In a subsequent interview, Robinson also said:

His company. which issues traveller's checks and credit cards and is the nation's third-largest diversified financial services business, "won't lose business" because of gasoline shortages that alter travel plans of many Americans this summer. Individuals may travel closer to home and certain travel-related businesses, eating establishments and hotels may suffer but overall travel spending is expected to continue to expand.

With currency exchange rates more favorable to travel in the U.S., there has been a "substantial" increase in the number of Europeans coming to this country, prompting American Express to establish new multilingual services and foreign exchange facilities through its own offices and at hotels that accept Amex credit cards.

A new program of helping restaurants conserve energy - at an average rate of $2,000 a year - is one of several special services American Express is developing to improve the financial health of eating establishments that accept cards. The firm also is developing computer-based analyses for small hotels, to help them pinpoint unusual cost problems in relation to other hotels of their size.

Despite defeat in its attempt to acquire McGraw-Hill Inc., the publishing firm, American Express continues to look for acquisitions in the communications industry, as broadly defined. "The communications field is intriguing. . . we've done lots of inside and outside research on it." Robinson stated. He expressed particular interest in television and cable-TV enterprises but ruled out a bid for a newspaper publishing firm because of "cosmetics" that might give the appearance of conflict of interest in editorial control.

At the same time, Robinson said this issue amounted to a "red herring" in the McGraw-Hill fight because of American Express' vow to establish an independent board for the publishing firm. "We could have come up with a realistic, responsible" method of averting American Express interference in editorial decisions, he said.

Backing up one theme of his address here, that business must be more open with the public and their own employes, Robinson noted that American Express internal publications reported fully on the McGraw-Hill battle - the pros and cons.

Robinson described this development as evidence that American Express is practicing "editorial independence" already. There were occasions he had an impulse to taks a hand in how the McGraw-Hill fight was being reported to his employes, but he kept hands off, Robinson conceded.

In his talk, Robinson called on his fellow business leaders to change their attitudes about the function, power and role of communications. The leaders must be committed to speaking up and not just "preaching to the choir," he asserted.

"Today, we chief executives often are reluctant to be interviewed. We often are reluctant to present our ideas in public debate. And sometimes we even hesitate to communicate openly with our employes," Robinson added.

Moreover, he continued, current public distrust will be overcome only when candid discussion replaces "a lack of clarity, business platitudes or self-serving sales pitches."

The American Express chief also had harsh words for the mass media: "Despite the massive amounts of information now available to us, our society seems unable to understand the complex issues facing it, unable to sort out viable alternatives and unable to establish common goals."

Robinson argued that for the American system to work, "there must be an informed public which has the facts presented in ways that it can digest."

Instead, he continued, "dramatic confrontation is highlighted while thoughtful analysis is often played down. . . the public is demanding that messages be compressed into neat, small packages. . . people in business, government and politics are learning to master the art of the buzz-word and the short descriptive phrase. . . they've learned that's the best way to capture the headlines."

In the American Express chief's opinion, this all adds up to a situation where "we are talking at each other instead of to each other. . . (a) monologue."

The Advertising Federation, separately, elected a Kraft Inc. executive as new natiional chairman, starting July 1. Chester Green, senior vice president for product development, marketing and research at Kraft, succeeds William Sharp, vice president of the Coca-Cola Co. CAPTION: Picture, JAMES D. ROBINSON III . . . warns of me-first attitude