Eye contact, to many, signals interest and trust. Doctors are taught to look patients in the eye, job interviewers favor those who meet their gaze, and even babies prefer direct, rather than oblique, stares. That our pupils dilate when we find someone attractive—a change that is mirrored if the feeling is mutual—is something we’ve known for a long time. In Renaissance Italy, women would go to the lengths of inducing dilation with belladonna extract, unaware it could cause blindness.

Serbian performance artist Marina Abramović considers eye contact a powerful mode of communication. In 2010, at New York’s Museum of Modern Art, Abramović spent 700 hours sitting in silence as nearly 1,400 people sat across from her and met her gaze. “There’s nothing happening. There’s no plo...