FOR THE PAST six weeks, a lively cultural exchange has been taking place at George Washington University's Department of Human Kinetics and Leisure Studies. Fifteen Costa Rican dancers and choreographers, selected by their country's government, have immersed themselves in the art of dance U.S.A.-style.

The GW program, subsidized by an Agency for International Development grant and administered by the Experiment in International Living, has included intensive courses in ballet, modern dance, improvisation, lighting, costuming and kinesiology. In addition, the Costa Ricans have had the opportunity to work with five guest choreographers, and will spend next week sampling the cultural wonders of Manhattan.

Friday and Saturday night at GW's Building K Dance Studio, the students will have the chance to demonstrate much of what they have absorbed here, as well as to present works they created and performed in before their U.S. experience.

The program will include modern dances by choreographers Liz Lerman, Maida Withers, Daniel West and Daniel McCusker, a Spanish dance by Marina Keet, plus eight Costa Rican- produced dances ranging from contemporary ballets to folk-oriented pieces.

COSTA RICAN DANCERS -- Friday and Saturday at 8, George Washington University's Building K Dance Studio, 817 23rd St. NW. Free admission. Call 676-6577.