> In the classic categorization task, infants first view a series of “familiarization” images from one object category (e.g., dinosaurs). Then they simultaneously view two new “test” images: a new exemplar from the familiarized category (e.g., another dinosaur; “familiar object”) and a new exemplar from a novel category (e.g., a fish; “novel object”). Infants’ ability to distinguish between the familiar and novel test images, measured by looking times, indicates whether they have formed the object category.