April 28, 1982

A picture caption on the front page yesterday misidentified Costa Rica's representative at the Washington meeting of the Organization of American States. He was Foreign Minister

As the Falkland Islands crisis worsens, American companies, which have doubled their investment in Argentina since the mid-1970's, have become increasingly concerned about their operations in the Latin American country. Argentine offices have been told by their parent companies in the United States to restrict travel in Argentina and to maintain a lower profile. These steps are being taken in order not to exacerbate any anti-American feelings that may arise because of the United States Government's historical political commitments to Britain. American companies have some $2.4 billion in direct investment in Argentina and, as the negotiations go on without any settlement, executives are becoming more pessimistic. The suggestion by Prime Minister Margaret Thatcher of Britain on Monday that further military action might be imminent has heightened corporate worries.

The people who would judge John W. Hinckley Jr. looked to the right, to the courtroom's side door, and he came forth today, flanked by security guards, still showing the clean-cut, youthful, slightly anxious gaze that has puzzled the nation since he shot President Reagan 13 months ago. That event, the ''historical deed'' referred to in Mr. Hinckley's own dark writings, convulsed this city a year ago. But this day the defendant and the court did not sift through details of the crime but the far more mundane calendar conflicts and potential prejudices in the lives of the ordinary people on the panel that will produce a jury of his peers. Dressed crisply in a tan summer suit and brown tie, Mr. Hinckley took his seat at the defense table as his trial began and stared forward, facing Federal District Judge Barrington D. Parker and, above on the wall, a white stone statue of Moses handing down the 10 commandments.

ON March 31, Ida Smith was admitted to a hospital in Hartford, paralyzed and unable to speak. The diagnosis was a stroke. Not until almost two weeks later, when a series of tests failed to show stroke damage, did the doctors consider another diagnosis: botulism. The misdiagnosis is not surprising. In 1981 there were only 28 reported cases of botulism in the United States. Most doctors have never seen a victim of the deadly food poisoning. On April 21, Mrs. Smith, 68 years old, who is almost completely paralyzed, was able to respond to simple yes and no questions by clenching her hand. She informed her doctor and officials from the Food and Drug Administration that the day before she became ill she had eaten canned salmon. The questions were not idle guesswork. They were based on an incident that had occurred two and a half months earlier in Europe. A 27-year-old Belgian, Eric Mathay, died of botulism on Feb. 7 after eating a pate made by his wife from a can of salmon imported from the United States. His wife became ill too, but survived.

Secretary of State Alexander M. Haig Jr. said today that, with the Soviet Union entering a period of leadership change, the United States faced ''a historic opportunity'' to influence future Soviet actions by making clear to the Kremlin leaders ''the benefits of greater restraint.'' In a policy speech to the annual meeting here of the Chamber of Commerce of the United States, Mr. Haig stressed the need for the United States to follow simultaneously the paths of strengthening its military forces and pursuing negotiations with the Soviet Union. He criticized what he called the extremes of relying too heavily on negotiations to improve relations or in advocating an ''all-out confrontation'' with Moscow to solve American problems. ''An American approach to the Soviet Union that balances strength and negotiations offers the best hope of significant accomplishment,'' he said in his speech at the Washington Hilton Hotel. ''We must place our policy in the context of important changes that are taking place in the world and in the Soviet empire that may make Moscow more amenable to the virtues of restraint.''