Infants are born with the capacity to perceive and even remember a good deal of visual information. But how do we know what infants are seeing? As they do not speak we cannot ask them. In the early 1960s a psychologist named Robert Franz started a revolution in infancy research by building a device that could monitor infants’ viewing patterns by noting the reflections on their pupils. By determining which object was looked at the longest when two objects were presented simultaneously, Franz was able to infer which object the infant preferred.