DESPITE their crucial differences, the William Merritt Chase and Berthe Morisot exhibits currently on view at the National Gallery of Art, and the Roger Brown and Lucian Freud shows now at the Hirshhorn, share a certain something: They're the sort of exhibitions most viewers expect, the kind of mainstream art you'd expect to find in London and New York, Paris and Chicago. But there are three other shows in town that stress the less familiar and focus our attention on artists and cultures often overlooked.

Hispanic Art in the United States: Thirty Contemporary Painters and Sculptors, the large and vivid survey which goes on view Saturday at the Corcoran Gallery of Art, is one such exhibition. The artists represented speak in various voices, but all stress their strong affinities for their Latin roots.

Two other exhibitions -- of American Indian Art -- are more cautious and traditional, but comparably moving. Lost and Found Traditions: Native American Art 1965-1985, a 380-object survey, is at the Renwick Gallery. A similar but smaller show, Plains Indian Art -- Continuity and Change, goes on view Friday at the National Museum of Natural History. Many of the recent objects on display -- the drums, dolls and peyote fans, the beadwork and the baskets -- seem to turn back from the present and reach out for the past. These exceptionally well-made moccasins and masks, belt buckles and blankets -- and even those small cases for throw-away Bic lighters -- convey a common message: The Indian has not vanished, his old ways have not been discarded or forgotten.