How Long to Fall in Love? 8.2 Seconds

Is he in love? Grab a stopwatch to know: At first encounter, the length of man’s gaze betrays his interest in a woman, a study of 115 students’ eye movements has uncovered. Four seconds say he’s unimpressed, but 4.2 more and he may be in love, the Telegraph reports. Researchers say the tactic—used exclusively by men—helps them find fertile mates. (More study stories.)