Three Taboos for Leaders.
Nervous mannerisms are twitchings, muscular spasms, scratching, swaying—and the like—that can’t be traced to physical disease. You see them in men and women who aren’t composed. More or less oblivious to their nervous mannerisms, they make you, as their observer, uncomfortable. Many, children especially, find nervous mannerisms contagious.
~ James F. Bender, The Technique of Executive Leadership (1950)