Joan Jonas, the U.S. Venice Biennale Representative

In an art world infatuated with the young and marketable, Joan Jonas is neither. At age 78, she is not yet a top-selling artist, and her multimedia work is challenging to collect and show. Yet the State Department has chosen Ms. Jonas to represent the U.S. at this year’s Venice Biennale—easily one of the highest honors for a living artist.

“It’s hard to conceive” of her new status as a sort of U.S. ambassador, said Ms. Jonas in an interview in her SoHo loft days before her departure for Venice, where the Biennale opens May 9. During the interview, she quieted her spirited white poodle, Ozu, with the occasional treat. “I can’t say that I represent all aspects of America. Who does? It’s an odd thing.”

Her election to the pavilion represents a victory for mature artists making complex, even unclassifiable, work. She has broken ground for decades. Some of Ms. Jonas’s first videos and performances in the early 1970s incorporated movement (usually her own), video feeds both live and taped (a radical gesture at the time) as well as drawing, masks and assorted totems that would reappear in later works. Her 1972 piece “Organic Honey’s Visual Telepathy”—in which she used mirrors and video feeds to play on our perception of space—evoked a multisensory experience well before such events became commonplace.

“What’s really current about Joan’s work is her multimedia aspect,” said Paul Ha,director of the Massachusetts Institute of Technology’s List Visual Arts Center, which submitted Ms. Jonas’s name to a State Department panel. “When you think about how we consume visual content... it’s not about looking at one screen. It’s about being consumed and surrounded.”

Representing the U.S. at the Biennale in 2013 was installation artist Sarah Sze , who constructs massive yet intricate structures from everyday objects. Earlier winners have included Ed Ruscha and Robert Gober.