Roni Horn: Portrait of an Image

What can we hope to learn about a person from a split-second portrait? The expression that confronts the viewer’s gaze—startled, friendly, or shy—undoubtedly affects how we feel about the person. But what if we are faced with dozens of photographs of the same person? Or several sets of seemingly identical photographs taken a fraction of a second apart and reflecting almost imperceptible change?

New York–based artist Roni Horn has long been fascinated with the concept of personal identity a...