Visitors to Rosslyn's Westpark Hotel may have wondered at the bizarre costumes, the extraterrestrial creatures perched on people's shoulders, and the rooms filled with comic book heroes and mythical beasts. They had wandered not into the Twilight Zone, but into the midst of a three-day tribute to science fiction called the Starcall Convention.

The convention, which began Friday and ends today, is more than fun and games, according to its organizers. They say it is to foster an interest in science and mathematics among young people and to remind Congress of legislation passed in 1958 that was to encourage the young to form science clubs.

Richard Preston, director of the International Star Foundation and one of the organizers of this first Starcall Convention, said he is concerned that young Americans are not getting as good an education in the sciences as are students in the Soviet Union.

Preston, a former employe of the U.S. Office of Education, advocates the use of science fiction literature in the classroom to stimulate young people's interest in the sciences and math.

About 250 people attended the convention yesterday, listening to lectures, and checking out the booths where books and science fiction memorabilia were displayed, but only about 30 of those were school-aged. Preston said it is difficult to get young people to go to a convention in summer, and the event was not highly publicized.

Susan Baskerville of Mclean, who taught school for nine years, said that while she thought it was a good idea to use science fiction to get students interested in science, she did not see the convention as a learning experience for young people but rather as a nostalgic activity for "Trekkies," (Star Trek fans) and other older science fiction buffs.

She said that young people are intrigued with the idea of outer space, but that "they are smart enough to know when it's for promotional purposes. The students I've taught would be turned off by this."

Hal Pomeranz, 15, a junior at Yorktown High School in Arlington, said some teachers and some of his peers look with skepticism on science fiction. "A lot of people take the 'it's-for-weirdos' attitude," he said, "and parents think it's junk literature. But people who are into it tend to take more math and science. I want a career in chemistry."

Donna Brown of Great Falls said she and her husband brought their two sons, Gary, 12, and Brian, 13, because they are interested in science fiction, and because Brian has already expressed an interest in aerospace engineering as a career. Among the lectures given during the convention was one on aerodynamics.

David Kyle, science fiction author and enthusiast, said, "If the young people don't lose their sense of wonder and thrill with new things, when they grow up they will still be young in outlook and spirit."