Petting dogs, and being touched by dogs, builds bonds we need

A ruby cavalier puppy lying on his master’s lap is a classic example of petting dogs

A ruby cavalier puppy lying on his master’s lap [1]

Bonding is necessary for normal development

The long-term discovery from Harlow’s work was that… isolated monkeys developed relatively normally physically, but abnormally socially. They did not interact with other monkeys well: terrified, they huddled in the corner when another young monkey was put into their cage.

Social interaction and personal contact is more than desirable: it is necessary for normal development.

Months later, Harlow tried to rehabilitate those monkeys whose early isolation so malformed them. He found that the best remedy was regular contact with young normal monkeys, whom he came to call “therapy monkeys,” in play. This restored some of the isolates to more normal social actors.

Petting dogs brings measurable changes that are very good

Simply petting a dog can reduce an overactive sympathetic nervous system within minutes: a racing heart, high blood pressure, the sweats. Levels of endorphins (hormones that make us feel good) and oxytocin and prolactin (those hormones involved in social attachment) go up when we’re with dogs. Cortisol (stress hormone) levels go down.

There is good reason to believe that living with a dog provides the social support which correlates with reduced risk for various diseases, from cardiovascular disease to diabetes to pneumonia, and better rates of recovery from those diseases we do get.

In many cases, the dog receives nearly the same effect. Human company can lower a dog’s cortisol level; petting can calm a racing heart.

Bonding with a pet can do the work that long-term use of prescribed drugs or cognitive behavioral therapy do.

Petting dogs is the first thing we reach for to build bonds

There are three essential behavioral means by which we maintain, and feel rewarded by, bonding with dogs. The first is contact: the touch of an animal…

Petting zoos have arisen to satisfy the urge to engage that animal on the other side of the fence not only by looking at it, but by touching it. Better still if the animal is touching back—with, say, a warm tongue or worn teeth grabbing at the food in your outstretched hands.

Children and even adults who approach me on the street as I walk with my dog want not to look at the dog, to watch her wag, to meditate on the dog—no, they want to pet the dog: to touch her. In fact, after a cursory rub, many people appear satisfied with that interaction. Even a brief touch is sufficient to bolster the feeling that a connection has been made.

Occasionally one might find one’s toes, hanging off the end of the bed bare, being licked.

Petting dogs — and in general, touch — is the first thing dogs reach for to build bonds

Dogs and humans share this innate drive for contact. … being held by the mother may be naturally comforting.

Watch an infant child, with limited vision and even more limited mobility, try to snuggle into his mother, his head rooting around for contact, and one is seeing just what newborn puppies look like.

Blind and deaf at birth, they are born with the instinct to huddle with siblings and their mother, or even with any solid object nearby. The ethologist Michael Fox describes the head of a puppy as a “thermotactile sensory probe,” moving in a semicircle until it touches something. This begins a life of social behavior reinforced by and embracing contact.

Wolves are estimated to make a move to touch one another at least six times an hour.

Petting dogs, and being touched by dogs, builds our bonds and maintains our bonds

Directed toward us, the dog’s youthful instinct becomes a drive to burrow a head under our sleeping bodies or to rest a head upon us; to push and bump us as we walk; to gently nibble or lick us dry. We find them touchable: furry and soft, right under dangling fingertips…

…full-body contact is preferred by some dogs, especially young dogs, and especially when they are the initiators of the contact. Dogs often find places to lie down that maximize contiguity of body with body. This might be a safe posture for dogs, especially as puppies, when they are entirely reliant on others for their care. To feel light pressure along the whole body is to have assurance of your well-being.

It is hard to imagine knowing a dog but not touching him—or being touched by him. To be nudged by a dog’s nose is a pleasure unmatched.[2]

  1. Tamaki, Rie. “Yuzu Ruby Cavalier King Charles Spaniel Puppy Sleeping on My Lap.” YouTube, 6 May 2013, Accessed 28 May 2017.
  2. Horowitz, Alexandra. Inside of a dog: What dogs see, smell, and know. Scribner, 2009, Scribd pp. 325-343.

Touch in infancy and adolescence teaches our brain networks what we value

Brain networks have patternmatching layers that make predictions and sense prediction errors. The anatomy shown here for vision has a counterpart for touch.

…the hierarchical neuronal message passing that underlies predictive coding.

…neuronal activity encodes expectations about the causes of sensory input, where these expectations minimize prediction error. Prediction error is the difference between (ascending) sensory input and (descending) predictions of that input.

On the left: this schematic shows a simple cortical hierarchy with ascending prediction errors and descending predictions.

On the right: this provides a schematic example in the visual system.[1]

Touch is crucial to emotion

Affective touch may… convey information about available social resources…[2]

interoception… refers to the perception and integration of autonomic, hormonal, visceral and immunological signals…—or more informally as the sense of the body ‘from within’.

…we propose that emotional content is determined by beliefs (i.e. posterior expectations) about the causes of interoceptive signals across multiple hierarchical levels.

Emotion produces conscious experience

It is tempting to speculate that deep expectations at higher levels of the neuronal hierarchy are candidates for—or correlates of—conscious experience, largely because their predictions are domain general and can therefore be articulated (through autonomic or motor reflexes).

…interoceptive predictions can perform physiological homoeostasis by enlisting autonomic reflexes… More specifically, descending predictions provide a homoeostatic set-point against which primary (interoceptive) afferents can be compared. The resulting prediction error then drives sympathetic or parasympathetic effector systems to ensure homoeostasis or allostasis, for example, sympathetic smooth-muscle vasodilatation as a reflexive response to the predicted interoceptive consequences of ‘blushing with embarrassment’.

Touch is central to selfhood and boundaries

…experiences of selfhood unfold across many partially independent and partially overlapping levels of description… A simple classification, from ‘low’ to ‘high’ levels, would range

  • from experiences of being and having a body…,
  • through to the experience of perceiving the world from a particular point of view (a first person perspective, …),
  • to experiences of intention and agency…,
  • and at higher levels the experience of being a continuous self over time (a ‘narrative’ self or ‘I’ that depends on episodic autobiographical memory,… )
  • and finally, a social self, in which my experience of being ‘me’ is shaped by how I perceive others’ perceptions of me…

In this putative classification, interoception plays a key role in structuring experiences of ‘being and having a body’ (i.e. embodied selfhood) and may also shape selfhood at other, hierarchically higher levels.[1]

The emotions we feel are largely predictions based on past experiences

…interoceptive inference involves hierarchically cascading top-down interoceptive predictions that counterflow with bottom-up interoceptive prediction errors. Subjective feeling states – experienced emotions – are hypothesized to depend on the integrated content of these predictive representations across multiple levels…[3]

Intuition suggests that perception follows sensation and therefore bodily feelings originate in the body. However, recent evidence goes against this logic: interoceptive experience may largely reflect limbic predictions about the expected state of the body that are constrained by ascending visceral sensations.[4]

Reward and motivation are predicted, based on emotions that are predicted, based on touch that was experienced previously

Reward is a complex construct comprised of a feeling and an action. Components of reward include the hedonic aspects, i.e. the degree to which a stimulus is associated with pleasure, and the incentive motivational aspects, i.e. the degree to which a stimulus induces an action towards obtaining it… Typically, the feeling is described as “pleasurable” or “positive” and the actions comprise behavior aimed to approach the stimulus that is associated with reward.[5]

…the representation of self is constructed from early development through continuous integrative representation of biological data from the body, to form the basis for those aspects of conscious awareness grounded on the subjective sense of being a unique individual.

Interoception refers to the sensing of the internal state of one’s body. …interoception… is proposed to be fundamental to motivation, emotion (affective feelings and behaviours), social cognition and self-awareness.[6]

  1. Seth, Anil K., and Karl J. Friston. “Active interoceptive inference and the emotional brain.”  Trans. R. Soc. B 371.1708 (2016): 20160007.
  2. Krahé, Charlotte, et al. “Affective touch and attachment style modulate pain: a laser-evoked potentials study.”  Trans. R. Soc. B 371.1708 (2016): 20160009.
  3. Seth, Anil K. “Interoceptive inference, emotion, and the embodied self.” Trends in cognitive sciences 17.11 (2013): 565-573.
  4. Barrett, Lisa Feldman, and W. Kyle Simmons. “Interoceptive predictions in the brain.” Nature Reviews Neuroscience 16.7 (2015): 419-429.
  5. Paulus, Martin P., and Jennifer L. Stewart. “Interoception and drug addiction.” Neuropharmacology 76 (2014): 342-350.
  6. Tsakiris, Manos, and Hugo Critchley. “Interoception beyond homeostasis: affect, cognition and mental health.Philosophical Transactions B: Biological Sciences 371.1708 (2016): 20160002.

Pleasant touch is best when it’s warm, close, soft, and slow

A pleasant touch to his head makes a dog squint and smile.

CT afferents sense pleasant touch

Unmyelinated afferents responding to light touch were first described in furry animals in 1939. In humans, a similar type of afferents was identified about 50 years later (CT, C tactile).

…the role of CT afferents… is to boost the feeling of pleasantness when touched by a friendly human being.

CT afferents are substantially more responsive to an initial touch stimulus than to succeeding stimuli. It may be speculated that the system is designed to make us more inclined to appreciate a friendly touch when first perceived.

The system would be of significance in supporting feelings of pleasure (reward), confidence, comfort, and security as you are close to your parents, lover, kin, or friends. Moreover, it may have a role in hormonal responses as well as in bonding individuals emotionally together.

Pleasant touch feels best at body temperature 

… afterdischarge in CT afferents is highly dependent on temperature, as it is more frequent and more prominent at lower than neutral temperatures. In a sample of 15 CT units, afterdischarge was seen in 80 % at 15 °C, but in only 13 % at… 32 and 42 °C…

… subjects’ feelings of pleasantness were optimal when the temperature of the moving object was neutral…

Pleasant touch is stronger when it’s closer in

CTs are abundant in the hairy skin of the human body, scarcer in the distal parts of the extremities and seem to be lacking altogether in the glabrous skin.

The pad skin of furry animals which is the homologue of human glabrous skin was primarily designed to take the wear and tear of walking and running.

Pleasant touch feels best when it’s soft

For slow to medium-velocity touch in the left graph, soft touch (open circles) and harder touch (filled circles) produced nearly the same CT response impulse rate. Even so, for slow to medium-velocity touch in the center graph and in the right graph, soft touch was rated as much more pleasant.

The most pleasant touch to CT afferents is relatively slow speed and is soft.

Pleasant touch feels best when it’s slow

… human CT afferents are tuned to a relatively slow speed of movements across the skin…

…in CT afferents maximal rate occurs at a fairly low speed (about 1–3 cm s −1 [0.4 to 1 inch per second]) which corresponds fairly well to human caressing movements.

… subjects’ estimates of pleasantness… are similarly tuned to the speed of movement…

… a prominent and sometimes long-lasting afterdischarge is seen in CTs…[2]

  1. Minette. “Not all Dogs Like Being Petted.” 12 Nov. 2012, Accessed on 5 Nov. 2016.
  2. Vallbo, Åke, Line Löken, and Johan Wessberg. “Sensual Touch: A Slow Touch System Revealed with Microneurography.” Affective Touch and the Neurophysiology of CT Afferents. Springer New York, 2016. 1-30.