Gesture. 1. Rotating the head horizontally from side-to-side a. to disagree, or b. to show misunderstanding of a speaker's words. 2. In an emotional conversation, a rhythmic, side-to-side rotation of the head to express disbelief, sympathy, or grief.
Usage: The head-shake is used to demonstrate a. cognitive dissonance, or b. emotional empathy.
Anatomy. Longus colli and splenius rotate the head from side-to-side, in tandem with sternocleidomastoid. The latter's prehistory as a branchiomeric muscle (originally used forrespiration and feeding) makes it responsive as a "gut-reactive" sign of refusal (see below; see also SPECIAL VISCERAL NERVE).
RESEARCH REPORTS: 1. The head-shake is a universal sign of disapproval, disbelief, and negation (Darwin 1872; according to Morris [1994:144] it is "widespread"). 2. The first nonverbal nay-saying may occur when babies head-shake to refuse food and drink. Rhesus monkeys, baboons, bonnet macaques, and gorillas similarly turn their faces sideward in aversion (Altmann 1967). 3. Children born deaf and blind head-shake to refuse objects and to disapprove when being touched by an adult (Eibl-Eibesfeldt 1973). 4. Evasive action shows in sideward head movements of young children to avoid the gaze of adults (Stern and Bender 1974). 5. A single sharp turn to one side (e.g., the Ethiopian head side-turn) can express negation as well (Morris 1994).