MEDFORD - The postcards for “Nancy Holt: Sightlines,’’ at the Tufts University Art Gallery through April 1, have a billiard-ball-size hole in the middle. Instructions on the back suggest holding the card up to a favorite outdoor view. I took a gander outside my kitchen window at the house next door. The circle in the postcard focused my vision on my neighbor’s window, and I suddenly saw it anew: A dark rectangle against a white ground within a dark circle. I also felt like a bit of a voyeur, and immediately stopped looking.
The experience of peering through a lens, and noting how that changes perception, is at the core of Holt’s work. She’s best known as a land artist - part of the movement in the 1960s and 1970s that brought attention to nature by making art out of the environment. The classic example of the movement is Robert Smithson’s “Spiral Jetty,’’ built in the Great Salt Lake in 1970. Smithson, who was married to Holt, died in a plane crash three years later, at 35.
