His research and teaching interests include medieval theories of vision and the image, the pictorial mechanics of Trecento painting, medieval medical and scientific imagery, and representations of the body in the Middle Ages. The author of articles on the "psalter map," on the "cruciform womb," and on Casper David Friedrich, he has contributed catalogue essays for various exhibitions and to Material Collective, an online forum devoted to visual and material culture. The recipient of a Meiss/Mellon Author's Book Award from the College Art Association and an ICMA-Samuel H. Kress Research Award from the International Center of Medieval Art, he has lectured widely and was a visiting fellow at Kunsthistorisches Institut in Florenz in 2009.