An infamous study by Nalini Ambady and Robert Rosenthal, “Half a Minute: Predicting Teacher Evaluations From Thin Slices of Nonverbal Behavior and Physical Attractiveness,” shows that students can predict a teacher’s ratings with significant accuracy after watching a 30-second silent video clip of the teacher at work. Resist the urge to attribute this to the superficiality of students’ ratings. What is the nonverbal magic that an audience recognizes so quickly?
I believe self-confidence is the critical non-verbal quality which audiences pick up on very quickly. Do you agree? Here is more, full of good advice, via Greg Mankiw (now a member of the American Academy) and Craig Newmark.