Part 4 of the 5 part series discussing the case of Etan Patz. Our expert this week is Dr. Nancy Franklin is an Associate Professor of Cognitive Science at Stony Brook University. Dr. Franklin's research focuses on memory representation, (1) how memories for imagined events  are similar to those for actual events and (2) how people evaluate their memories to determine whether remembered events had actually occurred. Dr. Franklin also studies source monitoring (the process by which a person determines the origin of a retrieved memory) and situation models (the memory representation for a described event or situation).