1. A system comprising: a processor; a camera; and memory, accessible by the processor and storing instructions that are executable by the processor to perform acts comprising: causing presentation of first content on a display surface; receiving, from the camera, an image that includes at least a portion of the display surface and a reflector having known dimensions to reflect a representation of a face of a user, the user being in a field of view of the camera; analyzing the image; determining a portion of the reflector associated with the face of the user; and displaying second content associated with the face of the user.