“Since Rudolf Stingel’s sleek midcareer survey opened at the Whitney Museum of American art in June, hundreds of visitors have been allowed to depart radically from traditional museum protocol (hands off) and have a go at the walls in the exhibition’s first gallery, using anything they happen to have with them: pens, money, credit cards, cellphones… Over the intervening months New York’s art-viewing public rose to the occasion: The room’s lower half is now equally dense with a kind of populist, manic, talking-in-tongues wallpaper.”