To support university students' understanding of mathematical proofs, pictures accompanying text are frequently used in textbooks as well as in lectures. However, it is unclear if such pictures influence the individual's reading behaviour. By recording the eye movements of eight mathematicians, we investigated whether and how adults with high expertise in mathematics pay attention to additional pictures when reading a written mathematical proof. We found that all participants paid attention to the pictures. As expected, in two out of three items, the text was fixated upon significantly longer than the picture. The data suggest that the participants tried to integrate information from text and picture by alternating between these representations. [For the complete proceedings, see ED597799.]