I quite like David Hockney’s collaged Polaroid snapshots. They do reveal much more than a single photograph, as the artist claims. You can contemplate them at your leisure and explore all the fissures between individual pieces of the mosaic as long as you wish. But I am dubious about Martin Gayford’s rendering of Hockney’s newest experiments with vision: films made with an array of nine high-definition cameras (“The Mind’s Eye,” September-October 2011). As the stills in the article show, the films can be seen on an array of nine screens arranged in three rows and three columns. “A lot of people have told me,” Hockney remarks, “that before they see these films they can’t imagine what nine cameras could do that one can’t. When they see them, they understand.” Well, I have not seen what nine cameras and nine screens could do, but I cannot imagine looking at more than one of the screens at a time. I could be aware of the neighboring screens, but peripheral vision would not allow me to capture much of the high-definition detail. It is different with Polaroid snapshots that remain still. If Hockney’s new work exploring the edges of art is about the mind’s eye, it strikes me as the mind of a fly.