We thank Sarah Deaton for developing the online survey and Jim Perkins for practical insight into the field of biomedical illustration. Azam Fikri Taifor, Andy Lu, and Katie Lewis contributed to early attempts at defining arrow meanings and coding textbook figures. This work was supported by a National Science Foundation grant (DUE-1359262) and an internal grant from the Rochester Institute of Technology College of Science (Dean’s Research Initiation Grant).