NEW HAVEN SHE says she plans to major in literature, but that that will ''probably change five times.'' She likes the lectures of the historian W. Gaddis Smith, but the class meets at 8:30 A.M., an hour when she says she would rather be sleeping, and by now, the second half of her freshman year, she feels confident enough to cut the class once in a while.
She is trying hard to be a typical Yale freshman, but Jodie Foster appeared last week to be a key ingredient in the mind of John W. Hinckley Jr., the man accused of shooting President Reagan last Monday. So there were reporters in front of her dormitory, at her history class, outside the library, and seemingly everywhere. She eluded them for more than 24 hours, and then spoke to some, but warned them that she planned to immediately ''resume my normal life.''
Miss Foster, who is 18 years old, began a career in acting 15 years ago, at the age of three, in a television commercial for Coppertone. She has played prominent parts in several movies, and several years ago took the role of a teen-age prostitute in ''Taxi Driver,'' a film in which a taxi driver stalks a United States Senator after his romantic overtures to one of the Senator's aides are rejected and later goes on a murderous rampage. Federal investigators believe that Mr. Hinckley may have been living out the role of the taxi driver.
For Miss Foster, this was a bizarre interruption in a largely successful struggle to lead a normal undergraduate life. For example, she seemed to have met the challenge of appearing in a show without stealing it. On March 26, she appeared in ''Getting Out,'' a play by Marsha Norman, in a production by Yale students at the Educational Center for the Arts, near the campus in New Haven. She steadfastly refused requests to be interviewed for a story on her stage debut, saying she would instead only speak about her role for stories about the play.
When Miss Foster talked with reporters on Wednesday afternoon, she looked like many other freshmen with complexion pallid from too many hours spent over books. She appeared to have what is known here as the ''freshman 10,'' the 10 pounds many freshmen gain in their first weeks here.
''I think of myself much differently from the way people think of me,'' she said. ''I never noticed there was a difference before today. I imagine that's something I'll have to be aware of.''
Asked what the difference was, she replied, ''I feel very young.'' Miss Foster said she was confident that the recent attention would have no effect on her relationship with her classmates. ''I have established myself at Yale,'' she said. ''I don't need to prove to them that I'm normal. They know I'm normal. I think the greatest thing about Yale is that people are intelligent enough, and respect me enough, to know that I'm one of the boys, and whatever happens (off campus) is another person.''
To some students at Yale, the connection between the apparent idol of an alleged assassin and one of their classmates was difficult to make. On Yale's Old Campus, in front of Miss Foster's dormitory, where a campus policeman held back a small group of reporters, an undergraduate stopped to ask one of the reporters why they had gathered. The reporter explained, but the young man seemed dissatisfied with the answer and asked a second reporter, who gave the same answer. The student paused, a blank look on his face, and then smiled. ''I get it.'' he said, ''It's April Fools' Day.''
Illustrations: photo of Foster
