The Social Psychology of Nonverbal Communication

A. Kostic, D. Chadee, A. Kostic, D. Chadee

• Publisher: Palgrave Macmillan
• Year: 2014
• ISBN:
  9781137345868
• Topic: Social Sciences
• Subtopic: Media Studies
• Index: Social Sciences

The Social Psychology of Nonverbal Communication gathers together leading nonverbal communication scholars from around the world to offer insight into a range of issues within the nonverbal literature with the aim to rethink current approaches to the subject.

Part I

Theoretical

1

Nonverbal Neurology: How the Brain Encodes and Decodes Wordless Signs, Signals, and Cues

David B. Givens

The brain, spinal chord, and peripheral nerves are seldom mentioned in research on human nonverbal communication. Though they play key roles in body-motion expressivity, the neurons, neural pathways, and brain modules that control movements are often discounted, or entirely left out of the picture. In this chapter, the nervous system plays a leading role in explaining how our facial expressions, hand gestures, and bodily postures are produced and deciphered. We begin with an overview of the nonverbal brain’s evolution, from ca. 500 million years ago to the present day.

Evolution of the nonverbal brain

The “nonverbal brain” (Givens, 2013) consists of those circuits, centers, and modules of the central nervous system which are involved in sending, receiving, and processing speechless signs. In right-handed individuals, modules of the right-brain cerebral hemisphere are considered to be more nonverbal, holistic, visuospatial, and intuitive than those of the more verbal, analytic, sequential, and rational left-brain hemisphere (Givens, 2013). Despite its size and abilities, our brain continues to house ancient neural layers, nuclei, and circuits that evolved millions of years earlier in vertebrate forebears – from the jawless fishes to more recent human ancestors (genus Homo) – for communication before the advent of speech (Givens, 2013). The nonverbal brain consists of six interrelated divisions which merged in an evolutionary process from ca. 500 million to two million years ago:

(1) The oldest neural division – the Aquatic Brain & Spinal Cord (Givens, 2013) – was present ca. 500 million years ago in the jawless fishes. It includes the spinal cord’s interneuron pools and motor neuron pathways (a) for tactile withdrawal, and (b) for the rhythmic, oscillatory movements of swimming (and much later, for walking and running, and for the bipedal rhythms of dance).

(2) In the subsequent Amphibian Brain, which originated ca. 380 million years ago, the hindbrain’s pontine reticular excitatory system became more elaborate (Kandel et al., 1991). The pontine tegmentum’s link to the spinal cord’s anterior-horn motor neurons and muscle spindles raised the body by exciting antigravity extensor muscles (enabling us to stand tall today, and to perform other versions of the vertebrate high-stand display). Further, the vestibulospinal pathway elaborated – from receptors in the inner ear via the vestibular nerve (cranial VIII), and via cerebellar fibers to the vestibular nucleus in the upper medulla – running the length of the spinal cord, for body posture (i.e., for basic stance) in relation to gravity. Further still, the tectospinal tract evolved, consisting of the superior (and inferior) colliculus and its links, via the brain stem, running (a) to cervical cord interneurons, then (b) to anterior-horn motor neurons, then (c) to spinal nerves, and finally reaching (d) muscle spindles for postural reflexes in response to sights and sounds (responses such as the startle reflex). Finally, the rubrospinal tract further evolved, with circuits running from the red nucleus of the midbrain (a) to thoracic cord interneurons, then (b) to anterior-horn motor neurons, and (c) to muscles and muscle spindles for the postural tone of our limbs’ flexor muscles.

(3) Subsequently in the Reptilian Brain, coming online ca. 280 million years ago, several new body movements were added. The vestibuloreticulospinal system evolved to control axial and girdle muscles for posture relative to positions of the head. The basal ganglia-ansa lenticularis pathway reverberated links between the amygdala and basal ganglia via the ansa lenticularis and lenticulate fasciculus to the midbrain tegmentum, red nucleus, and reticular system to spinal-cord interneurons required for today’s ATNR (asymmetrical tonic neck reflex) and the high-stand display.

(4) With the Mammalian Brain, originating ca. 150 million years ago, nonverbal communication became distinctively emotional. The amygdalo-hypothalamic tract became more elaborate. The central amygdala’s link to the hypothalamus, via the stria terminalis, provided wiring for defensive postures (such as the broadside display). Hypothalamus-spinal cord pathways adapted as well. The hypothalamus’s dorsomedial and ventromedial nuclei fed (a) indirectly via the brain stem’s reticular system, and (b) directly through fiberlinks to lower brain-stem and spinal-cord circuits to cord motor neurons for emotion cues such as anger. The septo-hypothalamo-midbrain continuum evolved. The medial forebrain bundle (from the olfactory forebrain and limbic system’s septal nuclei), via the hypothalamus’s lateral nuclei to midbrain-tegmentum brain-stem motor centers, mediated emotions such as fear. The cingulate gyrus facial circuit evolved. Links run from the anterior cingulate cortex (a) to the hippocampus, (b) to the amygdala, (c) to the hypothalamus, and (d) through the brain stem, and finally (e) to the vagus (cranial X) and facial (cranial VII) nerves which, respectively, control the larynx and facial muscles required for vocalizing (as in screaming) and moving the lips (as in smiling, frowning, and lip-compression).

(5) In the Primate Brain, which originated ca. 65 million years ago, manual dexterity and hand gestures, along with facial expressions and their recognition, were added to our nonverbal repertoire. The neocortex’s corticospinal tract further evolved. The posterior parietal cortex linked to supplementary motor, premotor, and primary motor cortices (with basal-ganglia feedback loops) via the corticospinal tract, to cervical and thoracic anterior-horn spinal interneurons, and to motor neurons in control of arm, hand, and finger muscles for the skilled movements of mime cues and the precision grip. Modules of the inferior temporal neocortex evolved to provide visual input (a) to the occipital neocortex’s parvocellular interblob system (V1 to V2 and V4), permitting recognition of complex shapes, and (b) to the inferior temporal cortex, permitting heightened responses to hand gestures and the ability to recognize faces and facial expressions.

(6) Finally in the Human Brain, which developed ca. four million-to-200,000 years ago in members related to the genus Homo, the corticobulbar tract further evolved. Corticobulbar pathways to the facial nerve (cranial VII) permitted intentional facial expressions such as the voluntary smile. Broca’s cranial pathways grew from Broca’s-area neocircuits via corticobulbar pathways to multiple cranial nerves, permitting human speech. And Broca’s spinal pathways also evolved. Broca’s-area neocircuits passing through corticospinal pathways to cervical and thoracic spinal nerves permitted manual sign language and linguistic-like mime cues.

Evolution of mirror neurons

The nonverbal brain’s evolution has been pieced together over time since the fifth century B.C. in Greece. Ever so gradually, a detailed picture of the human nervous system has emerged. Each time I open my copy of Gray’s Anatomy (Williams, 1995), I marvel at the extensive neural knowledge our species has amassed through the centuries since Hippocrates. And yet, in the 2,092 pages of my 1995 British edition of Gray’s, there is not a single mention of “mirror neurons.”

The shoulder-shrug

Since 1977, I have followed research on the shoulder-shrug display, first described by Darwin in 1872. While on the encoding (efferent) side, its distinctive body movements can be explained by appeal to circuits of the Aquatic Brain’s tactile-withdrawal reflex, on the decoding (afferent) side its neurology has remained something of a mystery. The perennial question is, how do we so readily understand the gesture’s meaning? Do we apprehend it by watching – which is to say, via experiential learning – or do we somehow infer what it means through “intuition”? Experience most certainly plays a role, but now it appears that an innate form of intuition based on mirror neurons is involved as well.

Mirror neurons

In the early 1990s, mirror neurons were discovered in the premotor cerebral cortex of macaque monkeys. Vittorio Gallese, Giacomo Rizzolatti, and colleagues at the University of Parma in Italy identified neurons that activate when monkeys perform certain hand movements – such as picking up fruit – and also fire when monkeys watch other primates perform the same hand movements. In The Imitative Mind, Andrew Meltzoff (2002) invoked mirror neurons to explain how human newborns, from 42 minutes to 72 hours old (mean = 32 hours), can imitate adult head movements, hand gestures, and facial movements (such as tongue protrusion, lip protrusion, mouth opening, eye blinking, cheek and brow movements, and components of emotional expressions). Mirror neurons have been located in Brodmann’s area 44 (Broca’s area) and other regions of the human brain.

Regarding the shoulder-shrug and other possibly innate nonverbal signs (such as compressed lips and the Adam’s-apple-jump, described below), mirror neurons provide brain circuitry that helps us intuit, decode, and understand their meanings. When we see a grasping-hand gesture, for instance, or hear an angry voice tone, mirror neurons set up a motor template – a prototype or blueprint in our own brain – that allows us to mimic the particular gesture or vocal tone. Additionally, through links to the Mammalian Brain’s limbic system, mirror neurons enable us to decode emotional nuances of the hand gestures we see and the tones of voice we hear. What has emerged from mirror-neuron research is that we are seemingly wired to interpret the nonverbal actions of others as if we ourselves had enacted them.

To explore in greater detail the nervous system’s role in encoding and decoding innately predisposed nonverbal signs, we focus below on five body parts: lips, neck, shoulders, hands, and feet. From head to toe, and throughout the world, these features are richly expressive.

Lip cues

Efferent cues (outgoing)

Lips are the muscular, fleshy, hairless folds that surround the human mouth opening. They may be moved to express an emotion, show a mood, pronounce a word, whistle, suck through a straw, and kiss. Their connection to the Mammalian Brain’s limbic system, and to the enteric (visceral) nervous system, renders them among the most emotionally expressive of all body parts.

Lip muscles. The principal lip muscle, orbicularis oris, is a sphincter consisting (a) of pars marginalis (beneath the margin of the lips themselves), and (b) pars peripheralis (around the lips’ periphery from the nostril bulbs to the chin). (P. marginalis is uniquely developed in humans for speech.) Contraction of orbicularis oris tenses the lips and reduces their eversion. Lips may be moved directly by orbicularis oris and by labial tractor muscles in the upper and lower lips. Lips may also be moved indirectly by nine (or more) additional facial muscles (e.g., by zygomaticus major in laughing) through attachments to a fibromuscular mass in the cheeks called the modiolus. That so many facial muscles interlink via the modiolus makes our lips extremely expressive of attitudes, opinions, and moods.

Expressions. Among the lips’ principal facial expressions are the smile (happiness, affiliation, contentment), the grimace (fear); the canine snarl (disgust, disliking), the lip-pout (sadness, submission, uncertainty), the lip-purse (disagreement), the sneer (contempt), and lip-compression (anger, frustration, uncertainty). That these expressions are emotional is because the facial muscles that shape them are controlled by special visceral efferent nerves.

Special visceral nerves. A special visceral nerve is a nerve that links to a facial, jaw, neck, shoulder, or throat muscle that once played a role in eating or breathing. Special visceral nerves are cranial nerves whose original role in digestion and respiration long ago renders them emotionally responsive today (see “Neural blueprint for emotion”, below). Special visceral nerves mediate those “gut reactive” signs of emotion we unconsciously send through facial expressions, throat-clears, sideward head-tilts, disgusted looks, and shoulder-shrugs. Nonverbally, these nerves are indeed “special,” because the muscle contractions they mediate are less easily (i.e., voluntarily) controlled than those of the skeletal muscles (such as the biceps, which is innervated by unemotional somatic nerves).

Neural blueprint for emotion. Before the Mammalian Brain, life in nonverbal world was automatic, preconscious, and predictable. Motor centers in the Reptilian Brain reacted to vision, sound, touch, chemical, gravity, and motion sensory cues with preset body movements and pre-programmed postures. With the arrival of night-active mammals, ca. 180 million years ago, smell replaced sight as the dominant sense, and a newer, more flexible way of responding – based on emotion and emotional memory – arose from the olfactory sense. In the Jurassic period, the Mammalian Brain invested heavily in aroma circuits to succeed at night as reptiles slept. These odor pathways gradually formed the neural blueprint for what was later to become our limbic brain. Smell carries directly to limbic areas of the Mammalian Brain via nerves running from the olfactory bulbs to the septum, amygdala, and hippocampus. In the Aquatic Brain, olfaction was critical for detecting food, foes, and mates from a distance in murky waters. Like an emotional feeling, aroma has a volatile or “thin-skinned” quality because sensory cells lie on the exposed exterior of the olfactory epithelium (i.e., on the bodily surface itself). Like a whiff of smelling salts, a sudden feeling may jolt the mind. The force of a mood is reminiscent of a smell’s intensity (e.g., soft and gentle, pungent, or overpowering), and similarly permeates and fades. The design of emotion cues, in tandem with the forebrain’s olfactory prehistory, suggests that the sense of smell is the neurological model for our emotions.

Pharyngeal arches. From an evolutionary standpoint, special visceral nerves are associated with the pharyngeal arches of ancient vertebrates. Nerves controlling the primitive pharyngeal arches are linked to branchiomeric muscles that once constricted and dilated “gill” pouches of the ancient alimentary canal. Paleocircuits of special visceral nerves originally mediated the muscles for opening (dilating) or closing (constricting) parts of the primitive gill apparatus involved in eating and breathing. Anatomically, a pharyngeal arch is a column of tissue in the throat (or pharynx) of the human embryo that separates the primitive visceral pouches or gill slits. Originally this issue was used by Silurian-Period jawless fishes as part of their feeding and breathing apparatus. Today, many human facial expressions derive from muscles and nerves of the pharyngeal arches. Originally, these arches were programmed to constrict in response to potentially harmful chemical signs detected in water. Today their special visceral nerves mediate displays of emotion by causing branchiomeric muscles to dilate or constrict.

Embryology. Pharyngeal arches are visible as swellings in the throat of the human fetus. Radical changes take place as these tissues grow into our maturing neck and face, but the underlying principles of movement established in the jawless fishes remains much the same. Unpleasant cues cause cranial nerves to constrict our mouth, eye, nose, and throat openings, while more pleasant sensations dilate our facial orifices to incoming cues. According to Chevalier-Skolnikoff (1973), “In mammals the primitive neck muscles gave rise to two muscle layers: a superficial longitudinal la...

Table of contents

• Cover
• Title
• Copyright
• Contents
• List of Figures and Tables
• Acknowledgments
• Notes on Contributors
• Introduction
• Part I Theoretical
• Part II Applied
• Author Index
• Subject Index