A head shake is a gesture in which the head is turned left and right along the transverse plane repeatedly in quick succession. In many cultures, it is most commonly, but not universally, used to indicate disagreement, denial, or rejection. It can also signify disapproval or upset at a situation, often with slower movement.
Meaning across cultures
Shaking the head to indicate "no" is widespread and appears in a large number of diverse cultural and linguistic groups, including the Indian subcontinent, the Middle East, Africa, Southeast Asia, Europe, South America, North America, and Australia. However, in some Southeastern European areas such as Bulgaria and southern Albania, the head shake is used for the opposite purpose—to indicate affirmation, meaning "yes." In those regions, nodding in fact means "no," the complete reverse of most other places in the world.
Origin
There are varying theories as to why the head shake is so frequently used to mean "no." An early survey of the head shake and other gestures was The Expression of the Emotions in Man and Animals, written by Charles Darwin in 1872. Darwin wrote to missionaries in many parts of the world asking for information on local gestures and concluded that shaking the head for "no" was common to many different groups. He also observed that babies, when hungry, search for their mother's milk by moving their heads vertically, but decline milk by turning their head from side to side.
Linguistic usage
The phrase "shake one's head" (or "shake your head") is defined as moving one's head from side to side to indicate disagreement, negation, disbelief, disapproval, or dismay. A relatively quick head movement from side to side indicates an emphatic "no," while a slower motion tends to indicate disbelief or dismay. The noun forms "headshake" and "headshaking" refer to the act of shaking one's head in this manner.
