Although our observers did judge a significant outward deviation for gaze between the two eyes, part of this was caused by an outward deviation from central by the presumably nonstrabismic eye. Any greater amount of outward deviation from the “strabismic” than the nonstrabismic eye can then be explained by a gaze overshoot induced by head turn, painting with a mirror, and angle kappas. In addition, Rembrandt’s apparent strabismus is seen only in those portraits painted during a few years early in his career, and portraits that Rembrandt and his students produced of other presumably nonstrabismic individuals often give a similar impression of strabismus.
There are several factors that can explain why some of Rembrandt’s self-portraits make him look strabismic without concluding that he actually was. Rembrandt and his students may also have painted this appearance as an artistic style.