What was going on when I was born?

THE rapid rate of increase in college costs has finally begun to drop, according to a survey by the College Board. After three years of annual increases of 10 to 11 percent in the cost of going to college, students and their families will have to cope with an increase of only 6 percent this fall, the College Board said yesterday. ''The slowdown in cost increases is good news for college students and their families,'' George H. Hanford, president of the College Board, said in announcing the results of the survey. ''And since most students do not attend the most costly public or private colleges, in fact individual expenses for the majority are likely to be at or below the national average.''

Thousands of people marched here today to protest the death of a man killed by police officers trying to arrest an American supporter of the outlawed Irish Republican Army. The victim, Sean Downes, was in the crowd that had gathered Sunday at an I.R.A. rally to hear Martin Galvin, publicity director of the New York-based Northern Irish Aid Committee, called Noraid, which supports the I.R.A. Mr. Downes was struck by a plastic bullet as policemen charged the crowd in an unsuccessful attempt to arrest Mr. Galvin, who had been barred from Northern Ireland by the British authorities. Mr. Galvin escaped. The march tonight was peaceful and at most times silent. Earlier in the day, there was scattered violence in West Belfast as youths burned cars, and after the march tonight some roadblocks were built and set on fire.

After impressing the financial community with the cost-cutting business practices it brought to the for-profit hospital field, Humana Inc. is now focusing on impressing the medical community by providing the most advanced hospital technology that money can buy. The company, whose 17,000 beds represent 2 percent of the national total, is doing this by expanding and upgrading its emergency rooms and operating suites. But more importantly, it is increasing the kinds of medical specialties available in many of its acute-care hospitals, even though the market share of for-profit hospitals has been declining. ''Humana is trying to become the most sophisticated in the marketplace,'' said David Lotson, an analyst at Paine Webber in Manhattan.

Antoinette Hatfield said today that she had received $55,000, not $40,000, from a Greek businessman whose trans-African pipeline venture was strongly endorsed by her husband, Senator Mark O. Hatfield. Senator Hatfield said he had made ''an error in judgment'' in failing to realize the possible public perception of his support of the pipeline and of the payments to Mrs. Hatfield. The Senate Ethics Committee and the Federal Bureau of Investigation are conducting separate inquiries of the circumstances. ''Nothing I can say today will change the past,'' Senator Hatfield said. ''You can't unscramble an egg. But I join my wife, Antoinette, to take such steps as I have. We've decided to give to charity an amount exactly equal to those fees which she received.''

LOS BANOS, THE PHILIPPINES IN the shadow of verdant tropical mountains, scientists have developed a number of promising new strains of rice in an effort to extend the Green Revolution to the hundreds of millions of Asians it has thus far failed to reach. The new varieties promise to give high yields without the costly irrigation required by the earlier ''miracle'' rice strains developed at the International Rice Research Institute here. The new strains have not yet been tested in farmers' fields, but one particularly promising variety has produced test yields more than twice as large as those from traditional varieties. If this and other new varieties being developed are successful, the resulting increase in the production of rice in nonirrigated areas would benefit the diets and household incomes of many of the two billion people, mostly in the developing countries of Asia, who eat rice as their staple and sell any surplus in good years. From 1960 to 1980, average yields in tropical Asia increased 40 percent, and the development of high-yielding varieties of rice was one of the main reasons for the improvement. But in the poorest nations that need it most - half the food energy consumed in developing nations comes from rice - the benefits of this Green Revolution have been limited, largely because these countries are least able to afford the irrigation and commercial fertilizer that make it possible.

A picture in Sports Pages on Friday with an article about architectural design related to the Olympics was incorrectly identified in the caption. It showed a new building for the Aerospace Museum in Exposition Park in Los Angeles.

The political lift that Walter F. Mondale hoped to gain from the Democratic National Convention and the nomination of Geraldine A. Ferraro for Vice President has not materialized at this stage of the campaign, according to the latest New York Times/CBS News Poll. The survey found that 62 percent of the nation's registered voters approved of having a woman as a Vice-Presidential nominee, but that the American electorate had a less favorable opinion of Mr. Mondale now than it did before the Democratic convention. The Times/CBS News Poll, taken by telephone among 1,188 registered voters Aug. 5 to last Thursday in a total sample of 1,616 adults, also pointed up Mrs. Ferraro's potential for helping the Democratic ticket while it underscored the doubts and reservations that Mr. Mondale confronted among a majority of potential voters. Gains for Mrs. Ferraro While Mrs. Ferraro remains less well known than Mr. Mondale, the survey found that on balance she was regarded more approvingly than he and that one-fourth of those who now back the Democratic ticket like her better than Mr. Mondale. By comparison, only one-tenth of those who back the Republican ticket like Vice President Bush better than President Reagan.

The United States sent three minesweeping helicopters to Saudi Arabia today to widen the search for the source of explosions in the Gulf of Suez and the Red Sea, the Administration announced. Pentagon officials said the helicopters would focus their efforts on keeping clear the channels from the Red Sea to Saudi ports. Two of the main Saudi ports on the Red Sea are Jidda and Yenbo, where Saudi naval bases are also situated. A State Department spokesman, Alan D. Romberg, told reporters that the helicopters had been sent in response to a request from the Saudi Government. The Saudis, he said, are interested ''in providing security in neighboring waterways, and we're supportive of that effort.''

IT is near the end of the cocktail party. Several guests are still talkative, friendly, charming and witty. But in one corner a woman is crying. Two men nearby are arguing, picking fights at every turn. Another guest has passed out. Yet another, who half an hour ago was happy and friendly, is now sick and depressed. All are under the influence of the only drug, alcohol, that is soluble in fat and water. As such, it invades every part of the human body, affecting virtually every cell and every biological pathway. It is a simple molecule with effects so complex that only a decade ago scientists avoided studying it. Now, however, researchers relying heavily on the tools of modern molecular science are finding important new explanations for the biological causes of alcoholism and its effects the human brain. And it is believed that these findings will provide important elements of understanding - physiological and genetic - for why people behave as they do at the above hypothetical coctail party: why some become alcoholics, but most do not; why some drinkers stay friendly, but others become hostile.

Waste Management Inc., the nation's largest waste collector, and Genstar Inc., a financial services, building supplies and real estate company, have teamed to buy SCA Services Inc., No. 3 in the waste collecting business, the three companies announced yesterday. The announcement, which included provisions for heading off antitrust objections to the merger, appeared to end two months of bidding for SCA. Terms of the definitive agreement call for Waste Management and Genstar to begin a tender offer for SCA common stock at $28.50 a share, or a total of $423.2 million. SCA was the most active stock on the New York Stock Exchange and jumped $2.365, to $23.50, on volume of 3,470,200 shares.

The Securities and Exchange Commission today accused the Stauffer Chemical Company of engaging in a multimillion-dollar fraudulent scheme to overstate its 1982 and 1983 earnings. In settling the charges, Stauffer officials characterized the issue as a dispute over accounting practices, and said the changes in its financial reports had been sanctioned by its auditors, Deloitte Haskins & Sells, who were not named in the complaint. S.E.C. officials contended, however, that the company knowingly made false and misleading statements about its financial condition. The commission's 14-page complaint, filed in United States District Court here, charged that the Westport, Conn., company enhanced its earnings reports by using accounting methods that were not generally accepted by the accounting profession. As a result, the agency said the company overstated its 1982 earnings by $31.1 million, or more than 25 percent of its reported earnings.

''There is a Catholic law on homosexuality. There is a Catholic law on birth control.