You might consider Dr. Alfred Adler and some of his ideas that have not been as highly researched as others. For example, inferiority/superiority, sibling position, and Early Recollections have all been done over and over. However, other topics are waiting to be explored. Check out my web site as a beginning: http://www.lifecourseinstitute.com Click on CONCEPTS for about 50 of his major ideas, and his name for a bio. You may want to look also at LEAP, in which I outline ten patterns we create as children to manage our lives. Any one of those ought to give you some ideas. The reasons I focus on Adler are (1) I am an Adlerian psychologist, and (2) Adler s ideas and influence are now being recognized as central to the creation of psychological theory and psycho-therapeutic practice for the past 100+ years. Pioneered group, family, marital therapies. Was friends with and teacher of Abraham Maslow and Carl Rogers among others. Was the main influence on neo-Freudians (Melanie Klein, Karen Horney, Harry Stack Sullivan, Eric Erickson, others). Now that I think of it, you might want to build your dissertation around the LEAP patterns themselves. Just an Idea.