Research in many disciplines has used eye-tracking technology to investigate the differences in the visual attention of experts and novices. For example, it has been shown that experts in art and chess spend more time than novices looking at relevant information. Thus, it may be helpful to give novices more direct insight into the way experts allocate their visual attention, for example using attentional cueing techniques. However, not much is known about how experts allocate their attention on physics problems. More specifically, we look at physics problems where the critical information needed to answer the problem is contained in a diagram. This study uses eye movements to investigate how the allocation of visual attention differs between experts and novices on these types of physics problems. We find that in several problems tested, those who answered a question correctly spend more time looking at thematically relevant areas while those who answer incorrectly spend more time looking at perceptually salient areas of the diagram.