Photographic memory is presumably an uncommon and unique trait. Characters with a photographic memory can remember things exactly as they were seen at the moment; like in a photograph. Sophie uses this in many books in the Keeper of the Lost Cities series to project memories in her memory log that appear very precisely with details. Keefe uses this ability to draw amazingly accurate drawings. Because of this ability, Sophie's mind can appear 'sharper' making it more overwhelming when Fitz or Mr. Forkle reads her mind.