The paper has to be on the history of cognitive psychology. Hermann Ebbinghaus is probably the true pioneer in cognitive psychology, so I would talk about his seminal work in memory. Another historical figure is Frederic Bartlett who studied memory for meaningful material. I would also include some other seminal figures in earlier cognitive psychology. Possibilities would be Atkinson & Shiffrin and their information processing model and Alan Baddeley and his work on working memory (short-term memory).