AT OCCUPY WALL STREET, Colleen Asper carried a blank placard. She’d set up a space in Zuccoti Park where people could make banners, but her own? Just an abstract shape. She couldn’t figure out what to say. People would ask her what she was holding or think she was being ironic or assume hers was a platonic shape or say, “Oh, that’s the logo for that new architecture firm.” But, it was the only thing she could carry, and those blank spaces keep coming back in her work.