One of the challenges to studying the effects of prior knowledge on learning is that it is difficult to control in an experiment … This highlights one of the trade-offs that happen when we conduct research on complex topics. Prior knowledge takes a long time to develop, and our development of that knowledge is based on many factors. This makes it difficult to manipulate! … I was therefore really interested to see a recent study that attempted to do just that - manipulate prior knowledge in order to examine its effects on learning.