Social connection is the experience of feeling close and connected to others. It involves feeling loved, cared for, and valued, and forms the basis of interpersonal relationships.
Feeling socially connected is related to the quality and number of connections one has with family, friends, and acquaintances. Going beyond the individual level, it also involves a feeling of connecting to a larger community. Connectedness on a community level benefits both individuals and society.
Connection is the energy that exists between people when they feel seen, heard and valued; when they can give and receive without judgement; and when they derive sustenance and strength from the relationship. —Brené Brown, Professor of Social Work at the University of HoustonIncreasingly, social connection is understood as a core human need, and the desire to connect as a fundamental drive. It is crucial to development; without it, social animals experience distress and face severe developmental consequences. In humans, one of the most social species, social connection is essential to nearly every aspect of health and well-being. Lack of connection, or loneliness, has been linked to inflammation, accelerated aging and cardiovascular health risk, suicide, and all cause mortality.
Feeling socially connected is related to the quality and number of connections one has with family, friends, and acquaintances. Going beyond the individual level, it also involves a feeling of connecting to a larger community. Connectedness on a community level benefits both individuals and society.
Related terms
- Social support is the help, advice, and comfort that we receive from those with whom we have stable, positive relationships. Importantly, it appears to be the perception, or feeling, of being supported, rather than objective number of connections, that appears to buffer stress and affect our health and psychology most strongly.
- Close relationships refer to those relationships between friends or romantic partners that are characterized by love, caring, commitment, and intimacy.
- Attachment is a deep emotional bond between two people, a "lasting psychological connectedness between human beings." Attachment theory, developed by John Bowlby during the 1950s, is a theory that remains influential in psychology today.
A basic need
Social connection involves feeling loved, cared for, and valued, and is as important to our well-being as food or water.
In his influential theory on the hierarchy of needs, Abraham Maslow
 proposed that our physiological needs are the most basic and necessary 
to our survival, and must be satisfied before we can move on to 
satisfying more complex social needs like love and belonging.
 However, research over the past few decades has begun to shift our 
understanding of this hierarchy. Social connection and belonging may in 
fact be a basic need, as powerful as our need for food or water.
 Mammals are born relatively helpless, and rely on their caregivers not 
only for affection, but for survival. This may be evolutionarily why 
mammals need and seek connection, and also for why they suffer prolonged
 distress and health consequences when that need is not met.
In 1965, Harry Harlow
 conducted his landmark monkey studies. He separated baby monkeys from 
their mothers, and observed which surrogate mothers the baby monkeys 
bonded with: a wire "mother" that provided food, or a cloth "mother" 
that was soft and warm. Overwhelmingly, the baby monkeys preferred to 
spend time clinging to the cloth mother, only reaching over to the wire 
mother when they became too hungry to continue without food.
 This study questioned the idea that food is the most powerful primary 
reinforcement for learning. Instead, Harlow's studies suggested that 
warmth, comfort, and affection (as perceived from the soft embrace of 
the cloth mother) are crucial to the mother-child bond, and may be a 
powerful reward that mammals may seek in and of itself. Although 
historic, it is important to acknowledge that this study does not meet 
current research standards for the ethical treatment of animals.
In 1995, Roy Baumeister proposed his influential belongingness
 hypothesis: that human beings have a fundamental drive to form lasting 
relationships, to belong. He provided substantial evidence that indeed, 
the need to belong and form close bonds with others is itself a 
motivating force in human behavior. This theory is supported by evidence
 that people form social bonds form relatively easily, are reluctant to 
break social bonds, interpret situations with how they affect their 
relationships in mind. He also contends that our emotions are so deeply 
linked to our relationships that one of the primary functions of emotion
 may be to form and maintain social bonds, and that both partial and 
complete deprivation of relationships leads to not only painful but 
pathological consequences.
 Satisfying or disrupting our need to belong, our need for connection, 
has been found to influence cognition, emotion, and behavior. 
Neurobiology
Brain areas
Social connection activates the reward system of the brain.
While it appears that social isolation triggers a "neural alarm system" of threat-related regions of the brain (including the amygdala, dorsal anterior cingulate cortex (dACC), anterior insula, and periaqueductal gray (PAG)), separate regions may process social connection. Two brain areas that are part of the brain's reward system are also involved in processing social connection and attention to loved ones: the ventromedial prefrontal cortex (VMPFC), a region that also responds to safety and inhibits threat responding, and the ventral striatum (VS) and septal area (SA), part of a neural system that is activated by taking care of one's own young.  
Key neurochemicals
Opioids
In 1978, neuroscientist Jaak Panksepp
 observed that small doses of opiates reduced the distressed cries of 
puppies that were separated from their mothers. As a result, he 
developed the brain opioid theory of attachment, which posits that 
endogenous (internally produced) opioids underlie the pleasure that social animals derive from social connection, especially within close relationships.
 Extensive animal research supports this theory. Mice who have been 
genetically modified to not have mu-opioid receptors (mu-opioid receptor
 knockout mice), as well as sheep with their mu-receptors blocked 
temporarily following birth, do not recognize or bond with their mother.
 When separated from their mother and conspecifics, rats, chicks, 
puppies, guinea pigs, sheep, dogs, and primates emit distress 
vocalizations, however giving them morphine (i.e. activating their 
opioid receptors), quiets this distress. Endogenous opioids appear to be
 produced when animals engage in bonding behavior, while inhibiting the 
release of these opioids results in signs of social disconnection.
 In humans, blocking mu-opioid receptors with the opioid antagonist, 
naltrexone, has been found to reduce feelings of warmth and affection in
 response to a film clip about a moment of bonding, and to increase 
feelings of social disconnection towards loved ones in daily life as 
well as in the lab in response to a task designed to elicit feelings of 
connection. Although the human research on opioids and bonding behavior 
is mixed and ongoing, this suggests that opioids may underlie feelings 
of social connection and bonding in humans as well.
Oxytocin
Opioids and oxytocin are neurochemicals that support the mother-child bond in humans and other mammals.
In mammals, oxytocin has been found to be released during childbirth, breastfeeding, sexual stimulation, bonding, and in some cases stress.
 In 1992, Sue Carter discovered that administering oxytocin to prairie 
voles would accelerate their monogamous pair-bonding behavior. Oxytocin has also been found to play many roles in the bonding between mother and child.
 In addition to pair-bonding and motherhood, oxytocin has been found to 
play a role in prosocial behavior and bonding in humans. Nicknamed the 
“love drug” or “cuddle chemical,” plasma levels of oxytocin increase 
following physical affection,
 and are linked to more trusting and generous social behavior, 
positively biased social memory, attraction, and anxiety and hormonal 
responses.
 Further supporting a nuanced role in adult human bonding, greater 
circulating oxytocin over a 24 hour period was associated with greater 
love and perceptions of partner responsiveness and gratitude,
 however was also linked to perceptions of a relationship being 
vulnerable and in danger. Thus oxytocin may play a flexible role in 
relationship maintenance, supporting both the feelings that bring us 
closer and the distress and instinct to fight for an intimate bond in 
peril.  
Health
Consequences of disconnection
A
 wide range of mammals, including rats, prairie voles, guinea pigs, 
cattle, sheep, primates, and humans, experience distress and long-term 
deficits when separated from their parent.
 In humans, long-lasting health consequences result from early 
experiences of disconnection. In 1958, John Bowlby observed  profound 
distress and developmental consequences when orphans lacked warmth and 
love of our first and most important attachments: our parents.
 Loss of a parent during childhood was found to lead to altered cortisol
 and sympathetic nervous system reactivity even a decade later, and affect stress response and vulnerability to conflict as a young adult.
In addition to the health consequences of lacking connection in 
childhood, chronic loneliness at any age has been linked to a host of 
negative health outcomes. In a meta-analytic review conducted in 2010, 
results from 308,849 participants across 148 studies found that people 
with strong social relationships had a 50% greater change of survival. 
This effect on mortality is not only on par with one of the greatest 
risks, smoking, but exceeds many other risk factors such as obesity and 
physical inactivity. Loneliness has been found to negatively affect the healthy function of nearly every system in the body: the brain,  immune system, circulatory and cardiovascular systems, endocrine system, and genetic expression.
Between 15-30% of the general population feels chronic loneliness.
Not only is social isolation harmful to health, but it is more and 
more common. As many as 80% of young people under 18 years old, and 40% 
of adults over the age of 65 report being lonely sometimes, and 15-30% 
of the general population feel chronic loneliness. These numbers appear to be on the rise, and researchers have called for social connection to be public health priority.
The "social" immune system
One of the main ways social connection may affect our health is through the immune system. The immune system's primary activity, inflammation,
 is the body's first line of defense against injury and infection. 
However, chronic inflammation has been tied to atherosclerosis, Type II 
diabetes, neurodegeneration, and cancer, as well as compromised 
regulation of inflammatory gene expression by the brain.
 Research over the past few decades has revealed that the immune system 
not only responds to physical threats, but social ones as well. It has 
become clear that there is a bidirectional relationship between 
circulating biomarkers of inflammation (e.g. the cytokine IL-6) and 
feelings of social connection and disconnection; not only are feelings 
of social isolation are linked to increased inflammation, but 
experimentally induced inflammation alters social behavior and induces 
feelings of social isolation.
 This has important health implications. Feelings of chronic loneliness 
appear to trigger chronic inflammation. However, social connection 
appears to inhibit inflammatory gene expression and increase antiviral 
responses. Performing acts of kindness for others were also found to have this effect, suggesting that helping others provides similar health benefits.
Why might our immune system respond to our perceptions of our 
social world? One theory is that it may have been evolutionarily 
adaptive for our immune system to "listen" in to our social world to 
anticipate the kinds of bacterial or microbial threats we face. In our 
evolutionary past, feeling socially isolated may have meant we were 
separated from our tribe, and therefore more likely to experience 
physical injury or wounds, requiring an inflammatory response to heal. 
On the other hand, feeling connected may have meant we were in relative 
physical safety of community, but at greater risk of socially 
transmitted viruses. To meet these threats with greater efficiency, the 
immune system responds with anticipatory changes. A genetic profile was discovered to initiate this pattern of immune response to social adversity and stress
 —  up-regulation of inflammation, down-regulation of antiviral activity
 —  known as Conserved Transcriptional Response to Adversity. The inverse of this pattern, associated with social connection, has been linked to positive health outcomes as well as eudaemonic well-being. 
Positive pathways
Social
 connection and support have been found to reduce the physiological 
burden of stress and contribute to health and well-being through several
 other pathways as well, although there remains a subject of ongoing 
research. One way social connection reduces our stress response is by 
inhibiting activity in our pain and alarm neural systems. Brain areas 
that respond to social warmth and connection (notably, the septal area) 
have inhibitory connections to the amygdala, which have the structural 
capacity to reduce threat responding.
Another pathway by which social connection positive affects health is through the parasympathetic nervous system (PNS), the "rest and digest" system which parallels and offsets the "flight or fight" sympathetic nervous system (SNS). Flexible PNS activity, indexed by vagal tone, helps regulate the heart rate has been linked to a healthy stress response as well as numerous positive health outcomes.
 Vagal tone has been found to predict both positive emotions and social 
connectedness, which in turn result in increased vagal tone, in an 
"upward spiral" of well-being. Social connection often occurs along with and causes positive emotions, which themselves benefit our health.
Measures
Social Connectedness Scale
This scale was designed to measure general feelings of social 
connectedness as an essential component of belongingness. Items on the 
Social Connectedness Scale reflect feelings of emotional distance 
between the self and others, and higher scores reflect more social 
connectedness.
Measuring feelings of social isolation or disconnection can be 
helpful as an indirect measure of feelings connectedness. This scale is 
designed to measure loneliness, defined as the distress that results 
when one feels disconnected from others.
Relationship Closeness Inventory (RCI)
This measure conceptualizes closeness in a relationship as a high
 level of interdependence in two people's activities, or how much 
influence they have over one another. It correlates moderately with 
self-reports of closeness, measured using the Subjective Closeness Index
 (SCI).
These scales were developed to measure the difference between 
liking and loving another person -- critical aspects of closeness and 
connection. Good friends were found to score highly on the liking scale,
 and only romantic partners scored highly on the loving scale. They 
support Zick Rubin's conceptualization of love as containing three main 
components: attachment, caring, and intimacy 
Personal Acquaintance Measure (PAM)
This measure identifies six components that can help determine 
the quality of a person's interactions and feelings of social 
connectedness with others: 
- Duration of relationship
- Frequency of interaction with the other person
- Knowledge of the other person's goals
- Physical intimacy or closeness with the other person
- Self-disclosure to the other person
- Social network familiarity—how familiar is the other person with the rest of your social circle
Experimental manipulations
Social
 connection is a unique, elusive, person-specific quality of our social 
world. Yet, can it be manipulated? This is a crucial question for how it
 can be studied, and whether it can be intervened on in a public health 
context. There are at least two approaches that researchers have taken 
to manipulate social connection in the lab:
Social connection task
This task was developed at UCLA by Tristen Inagaki and Naomi 
Eisenberger to elicit feelings of social connection in the laboratory. 
It consists of collecting positive and neutral messages from 6 loved 
ones of a participant, and presenting them to the participant in the 
laboratory. Feelings of connection and neural activity in response to 
this task have been found to rely on endogenous opioid activity.
Closeness-generating procedure
Arthur Aron at the State University of New York at Stony Brook 
and collaborators designed a series of questions designed to generate 
interpersonal closeness between two individuals who have never met. It 
consists of 36 questions that subject pairs ask each other over a 45 
minute period. It was found to generate a degree of closeness in the 
lab, and can be more carefully controlled than connection within 
existing relationships. 




