A: According to Jason Surrell in his Haunted Mansion book, “The moving bust illusion was one of [Imagineer] Rolly Crump’s so-called happy accidents. As part of their research and development for The Hall of Presidents [which had been going on since the late 1950s], Imagineers had created a mold of Abraham Lincoln’s face, an artificial life mask of sorts. One day Rolly and Yale [Gracey] happened to stroll past the backside of the face, and as they did so, realized that from the reverse angle, it appeared as though Honest Abe’s eyes were following their every move.”