What was going on when I was born?

Under this heading, The Times amplifies articles or rectifies what the editors consider significant lapses of fairness, balance or perspective.

Last year, when most of this city's major banks were mired in trauma and uncertainty, the American National Bank and Trust Company of Chicago, the city's fifth-largest bank, put together a record year by capitalizing on the problems of its hometown competitors. It did this by continuing to do what it does best: serving the highly profitable ''middle market'' of small and medium-sized companies. So successful was 1984 for American National that its earnings jumped by 32 percent, its client roster by more than 20 percent and its loans outstanding by 30 percent. In addition, the First Chicago Corporation, the city's largest bank holding company, impressed by American National's record, acquired the bank from the Walter E. Heller International Corporation last May.

A caption and article in Business Day yesterday about market specialists on the New York Stock Exchange misspelled the name of Michael Creem, and of his firm, Creem & Creem.

A cross two stories high adorns an outside wall of St. Brigid School on the Lower East Side, and inside the building there are crucifixes in all but three classrooms. Overt signs of religion are banned from those three rooms of the Roman Catholic school because teachers assigned by the Board of Education work in them. Arrangements like this, with church and state carrying out educational functions in close proximity, serve 20,000 students in 253 of the city's nonpublic schools. All but one of the schools are under religious auspices, mostly Catholic or Jewish, and altogether $30 million in Federal money is spent by the Board of Education on remedial education programs in the parochial schools.

COMPUTERS have long been able to draw fairly simple shapes such as balls, blocks and even airplane wings. But when it came to drawing more complex natural phenomena, like wispy clouds or jagged mountain peaks, computers could manage only crude approximations. Now, however, a once obscure mathematical concept known as fractals is allowing computer scientists to surmount those barriers. Fractals are mathematical curves that define some order in the midst of seemingly chaotic phenomena, like the shape of a coastline or cloud. And they are becoming important not only for computer graphics, but for many areas of science involving seemingly random phenomena, including the turbulent flow of fluids, the fracturing of metals, the clustering of galaxies in the universe, the distribution of vegetation in Georgia's Okefenokee Swamp,

AS the world epidemic of acquired immune deficiency syndrome, or AIDS, continues unabated, a new apprehension has begun to take hold among some medical experts. They say their suspicion is growing stronger that the disease may now pose a threat to the heterosexual community, though they hasten to add that this suspicion is based on preliminary interpretations of figures collected mainly in Africa and Haiti and on only scant data from the United States. Other health authorities still contend, however, that the risk to heterosexuals in the United States is so small that no new public health recommendations are warranted. At present, the established risk groups are homosexuals, intravenous drug users, hemophiliacs and Haitians who recently moved to the United States. Since 1981, when the baffling disease was first recognized in New York and California, medical researchers have made enormous strides. They have discovered a virus believed to cause AIDS, and they have begun to unravel some of the mysteries of the natural history of the affliction that has been diagnosed in 37 countries. Most of the cases have been reported in the United States.

An outhouse seat that once served a Victorian home here could become an artistic treasure and a gold mine. The three-hole seat, which was used for years behind a Civil War-era house on the north side of Main Street, was sold at auction in November for $50. Then, last month, Elaine de Kooning wrote a one-paragraph letter authenticating the 99-inch by 22-inch seat as an unsigned work by her husband, Willem de Kooning, the artist. In an interview, Mrs. de Kooning said that 30 years ago her husband, some of whose canvases have brought more than $2 million, painted the seat ''in a few minutes'' for the occasion of a croquet party. It was an attempt to make the wood look like marble and disguise its plebeian past.

The Advertising Column last Friday incorrectly reported a previous position held by Barbara Hannah Marks, now with Success magazine. She was with Computer Retail News.

The Continental Illinois Corporation, which the Government rescued last year, reported a 44.1 percent increase in fourth-quarter net income, to $36.6 million, from $25.4 million in the 1983 period. But per-share earnings plunged 78.9 percent, to 12 cents, from 57 cents. That largely reflected the dilution under the plan giving the Federal Deposit Insurance Corporation options to acquire 160 million shares. Before the rescue, there had been 40.3 million common shares outstanding.

TUESDAY, JANUARY 22, 1985 International The key Sunni Moslem political leader in southern Lebanon was critically wounded in a bombing at his home in the port city of Sidon, the state radio reported. The attack on the leader, Mustapha Saad, heightened fears of civil strife after Israeli forces withdraw from the Sidon area. (Page A3, Column 1.) The power of Britain's labor unions has plummeted. Prime Minister Margaret Thatcher has won a series of changes that make it harder to maintain a closed shop, harder to win authority for a strike and easier to oust union officials. (A4:1-2.) National

Markets Several stock market averages soared to record levels as both large and small investors went on a buying spree. The rally startled many market analysts, who said that the surge had no direct connection with the inauguration of President Reagan but instead reflected general economic optimism. The Standard & Poor's 500- stock index jumped 3.91 points, to 175.23. The New York Stock Exchange composite index closed at 101.12, up 2.08, the first time it has topped 100. The Dow Jones industrial average roseb 34.01 points, to 1,261.37, but did not set a record. (Page A1.) Short interest on the Big Board fell 13.4 million shares, or 6.1 percent, in the month ended Jan. 15, to 207.3 million shares. (D4.)

A NEW generation of psychoanalytic thinkers is undertaking the kind of rigorous research that critics contend has been grossly lacking in the discipline but that is essential if psychoanalysis is ever to become truly scientific. In the process, they are discarding some long-held psychoanalytic tenets, modifying others and establishing an empirical basis for still others. This scientific treatment of psychoanalysis, some psychoanalysts say, threatens to diminish the richness of their clinical craft by reducing a complex process to simplistic terms. However, a growing number of psychoanalysts are coming to believe that, if the discipline is to survive and flourish, it will have to be tested and refined in accordance with the canons of scientific method. Although it is much too early for a consensus, many involved in the new effort are proposing which parts of analytic theory can be validated and which cannot. For instance, according to Jonathan Winson, a neuroscientist at the Rockefeller University, ''Some concepts just don't stand up.''