headnod

We drank and nodded at each other. --Private detective Philip Marlowe with racketeer Eddie Mars (The Big Sleep by Raymond Chandler, 1939, p. 131)

Gesture. 1. A vertical, up-and-down movement of the head used to show agreement or comprehension while listening. 2. A flexed-forward, lowering motion of the skull, used to emphasize an idea, an assertion, or a key speaking point.

Usage: Rhythmically raised and lowered, the head-nod is an affirmative cue, widely used throughout the world to show understanding, approval, and agreement. Emphatic head-nods while speaking or listening may indicate powerful feelings of conviction, excitement, or superiority, and sometimes even rage.

Anatomy. 1. In the affirmative head-nod, longus capitis, rectus capitis anterior, and longus colli flex our neck and head forward, while splenius (a deep muscle of the back) and trapezius bend the head and neck backward. 2. In the emphatic head-nod, forced expiration while stressing an important word contracts muscles of the abdominal wall (i.e., the oblique and transverse muscles, and latissimus dorsi), which depress our lower ribs and bend our backbone and head forward (Salmons 1995:818-19).

Evolution. Paleocircuits for the reptilian head-bobbing display (used aggressively by lizards, e.g., to affirm their presence in Nonverbal World) may underlie the nods we ourselves use to reinforce our words. The reptilian principle of isopraxism may explain why speakers and listeners often nod in synchrony.

U.S. politics. "President Donald Trump 'nodded with approval' at the suggestion of a meeting with Russian's [sic] Vladimir Putin, according to a court filing that seeks leniency for a former campaign aide [George Papadopoulis] who lied to the FBI" (Spokesman-Review, Sept. 2, 2018, NEWS p. 3).

RESEARCH REPORTS: 1. Though other types of affirmative head movements have been observed cross-culturally (LaBarre 1947), the affirmative head-nod is well-documented as a nearly universal indication of accord, agreement, and understanding (Darwin 1872; Eibl-Eibesfeldt 1970, 1971; Morris 1994). 2. "Others see it [the head-nod] as an abbreviated form of submissive body-lowering - in other words, as a miniature bow" (Morris 1994:142).

Neuro-notes I. That we head-nod in agreement may be due, in part, to trapezius's origin as a "gut reactive" branchiomeric muscle for respiration and feeding (see SPECIAL VISCERAL NERVE). 1. Today, e.g., it assists movements of a baby's head in accepting the breast--a behavior some have used to explain the universality of the head-nod cue (e.g., Morris 1994:142). 2. Moreover, the accessory nerve (cranial XI, which innervates trapezius), has a relationship with the vagus nerve (cranial X, which innervates the larynx in producing "hmm," "uh huh," and other "digestive" vocalizations). Thus, the affirmative head-nod may reflect an agreeable response to food. 3. Regarding the emphatic head-nod, the strong physical emphasis during its downward phase suggests a separate origin from the "yes" nod, which begins with an upward motion.

HEAD-NOD GESTURES: A more detailed look:

Is the head nodded vertically in affirmation, and shaken laterally in negation? --Charles Darwin (1872, p. 23)

The human head-nod is a vertical, up-and-down (or down-and-up) movement that is often used to show agreement or comprehension while listening. The flexed-forward, lowering motion of the skull is also used to emphasize an idea, an assertion, or a key speaking point. Rhythmically raised and lowered as an affirmative sign, it is widely used throughout the world to show understanding, approval, and agreement. Emphatic head-nods while speaking or listening, on the other hand, may indicate feelings of conviction, excitement, or superiority, and sometimes anger or rage. Students of head-nodding often correlate the gesture with linguistic syntactical and semantic features of speech. Beginning with Darwin (1872), many have assessed the emotional dimensions of nodding as well.

Eight muscles are key players in the head-nod. In the affirmative nod, longus capitis, rectus capitis anterior, and longus colli muscles (all supplied by cervical spinal nerves) flex the neck and head forward, while splenius (a deep muscle of the back, also supplied by cervical spinal nerves) and upper trapezius (supplied by cranial nerve XI) bend the head and neck backward. In the emphatic head-nod, forced expiration while stressing a word contracts muscles of the abdominal wall (oblique [supplied by the first cervical spinal nerve] and transverse muscles [supplied by intercostal nerves], and latissimus dorsi [supplied by cervical spinal nerves]), which depress the lower ribs and bend the backbone and head forward (Salmons 1995, pp. 818-19). Electromyographic measurements show that the sternocleidomastoid muscles (supplied by cranial nerve XI) are involved in both flexion and extension of the neck (Salmons 1995, p. 805).

Measured in evolutionary terms, the emphatic head-nod may reach back ca. 280 million years ago to the beginning of reptiles. Paleocircuits for the reptilian up-and-down head-bobbing display (used aggressively by lizards today to affirm their physical presence in space and time) may underlie the nods we ourselves use to reinforce assertions and accent words (see below: "(4) Reptilian-brain centers"). The reptilian principle of isopraxis (MacLean 1990), for instance, may explain why speakers and listeners often nod together in synchrony (see below: "Video"). Meltzoff (2002, p. 23) invokes mirror neurons to explain how human newborns from 42 minutes to 72 hours old (mean = 32 hours) can imitate adult emotional expressions and head-movement gestures.

Though other types of affirmative head movements have been observed cross-culturally (LaBarre 1947), the affirmative head-nod is well-documented as a nearly universal indication of accord, agreement, and understanding (Darwin 1872, Eibl-Eibesfeldt 1970, Morris 1994). Researchers have found cultural differences in the meaning of head-nod cues. Samovar and colleagues, for instance, report a key variance in the American and Chinese use of the sign. In the U.S., head-nodding bespeaks agreement, whereas, ". . . the head nod is used by the Chinese to acknowledge the speaker, not to signal agreement with what is said" (Samovar et al. 2007, p. 302). Despite this difference, the nodding motion itself is an emotionally positive, affirmative signal in both countries.

According to Mehrabian, ". . . frequent head nodding, in addition to communicating liking to a listener, implies a less confident or submissive speaker" (1972, p. 81). In a review of more than 70 research articles on human head movements, Harrigan (2005) found that nearly 80 percent dealt with nodding. Of the articles she reviewed, 55 dealt with the head-nod itself, 14 with the head-shake, eight with the head-tilt, and 25 with "any" head movement (Harrigan 2005). These frequencies may be used as a crude measure of the importance researchers attribute to the head-nod as compared to other head-movement gestures.

Measured sequentially as units in the kinesic flow of behavior, Birdwhistell proposed three "kinemes" (gestures having linguistic-like properties) for head-nodding: ". . . the 'one nod,' the 'two nod,' and the 'three nod' . . ." (1970, p. 100). He attempted--unsuccessfully--to calculate a measurement for the duration of the three-nod gesture, to distinguish it from the occurrence of three one-nod gestures (1970, p. 162). In a study of conversations, Nori and colleagues similarly proposed three values for the head-nod cue: "single," "double," and "repeated," noting that Japanese subjects tended to use single, while German subjects used more repeated, head-nods (Nori et al. 2011, p. 414). In his study Wilbur (2000, p. 201) measured the relative position of head-nods as units in the flow of American Sign Language (ASL), finding that "large, slow nodding" marked a signer's commitment to the truth of an assertion, while "small, rapid noddings" marked a signer's "hedging [comparable to using "sort of" and "kind of" phrases in spoken English] or counterfactuals [i.e., untruthful assertions]" (p. 201).

Video. In a video study of head movements by native speakers of American English, McClune found that speaker head-nods were often closely followed by listener nods, within 0.7 second in the example given (2000, p. 874). Their close proximity in time, McClune concluded, is an indication that the latter nods were elicited or triggered by the speaker's head-nods. Listeners, she notes, are "extraordinarily sensitive" to such speaker nods (2000, p. 855), which seem to function as gestural requests for listener input.

"During face-to-face conversation," Lee and colleagues (2009, p. 9) write, "the speaker's head is continually in motion." More often than not, head-nods have a measurable emotional component as well. In a study of head-nod gestures using the Affect Analysis Model (AAM) of emotional recognition, Lee and colleagues (2009, p. 14) found that head-nods most frequently occurred at the beginning of sentences, and with interjections, proper nouns, conjunctions, and adverbs. It is noteworthy that each of these occurrences is marked by some degree of emotion.

Beginning a new sentence implies feelings of self-assurance, viz., that it is now one's turn to speak. An interjection, meanwhile, is "A part of speech usually expressing an emotion, and capable of standing alone, such as Ugh! or Wow!" (Soukhanov 1992, p. 941). Since proper nouns are used as names for "unique individuals, events, or places" (Soukhanov 1992, p. 1452), they are likely to provoke more feelings than are elicited by ordinary nouns. Conjunctions mark momentary pauses between words, phrases, and sentences, pauses often brought on by indecision, uncertainty, and doubt. And finally, an adverb marked by a head-nod is usually an "intensifier": "A linguistic element, such as the adverb extremely or awfully, that provides force or emphasis" (Soukhanov 1992, p. 939). Intensifiers enhance the emotional content of the words they modify.