We ran a very similar study back in 2004 in which participants were shown photos of people. Those with the 2nd longest stare rates were of people who satisfied the traditional 20th century/modern concepts of "beauty." (That has a higher degree of subjectivity, to be sure.) But the photos that were looked at longest were images of obviously grotesque, malformed, or extremely terrified people. The theory was that looking at something pleasing elicits less complex brain responses versus looking at something terrifying or morbid or in pain. Brain wave analysis seems to confirm that.
Sorry, Boston. (just kidding.)