During an introductory psychology course at Britain’s University of Essex in 2009, Arnold Wilkins asked his class to participate in a quick experiment. Wilkins projected two images on a wall and asked students to write down whether they found either of them disturbing. One was a photograph of a woody landscape. The other was a close-up of a lotus-flower seedpod — a flat-faced pod pocked with small holes. Most of the students were unmoved, but one, freshman An Le, recalls being both transfixed and revolted by the lotus image. “It felt like I was in shock,” he says.