Nicolas Christakis and James Fowler offer a slide summary of the first chapter of their book Connected: The Surprising Power of Our Social Networks. Happiness is contagious. Your future spouse is likely to be your friends friend. Your friends friends friends can make you fator thin. We think we are individuals who control our own fates, but as Christakis and Fowler demonstrate, we are merely cells in the nervous system of a much greater beast. If someone you barely know reads Connected, says Daniel Gilbert, author of the bestselling book Stumbling on Happiness, it could change your life forever. How? Read it yourself and find out." Your comments are appreciated.
Chapter 1In the Thick of It
The simplest network is a dyad or pairDyads agglomerate to form large interconnected webs
Line = a relationship between two people more embedded = central
less embedded = periphery
Node = a person embedded: the degree to which a person is connected within a network
The Bucket BrigadeLinear Mutual ties(flow in both directions)
Photo from FEMA
The Telephone TreeInformation is directional (inbound and outbound ties) Reduces number of steps Creates cascade effect
The Military SquadTightly interconnected groups Two-way tie between all members of squad Squad is more intra-connected than inter-connected with other squads
TermsA Social Network: consists of all the connections and ties within a group or collection of groups
A group is a collection of individuals defined by a common attribute (it need not contain information about connections)
TermsThe Shape of a network = its structure or topology
Terms Contagion: what flows across ties(germs, money, violence, fashions, organs, happiness, obesity, etc.)
Connection: who is connected to whom(ties to family, friends, co-workers, etc.)
Homophily: the tendency to associate with people who resemble ourselves(love of being alike)
We shape our network We determine structure of our network: how many people we are connected toThe average American has 4 close social contacts known as their core discussion network The same number of people can be arranged and connected in different ways, and have different topologies
We shape our network2. We influence the density of interconnections between friends and familywe introduce friends from separate groups to one another
We shape our network3. We control how central we are within the social networkAre you the life of the party? Or the wall flower?
TransitivityTransitivity: a relationship is transitive when all those involved know each other (form a triangle) Those with high transitivity (e.g. person A) are deeply embedded within a single group
Those with low transitivity (e.g., person B) act as a bridge between different groups, connected with people who do not know one another
InfluenceContagion: what flows across ties (germs, money, violence, fashions, organs, happiness, obesity) Dyadic Spread: the tendency of effects to spread from one person to their direct social ties
Hyperdyadic spread: the tendency of effects to spread from person to person to person (outside a persons direct social ties)
What Are You Looking At? exploring the Stanley Milgrams sidewalk experimentimportance of reinforcement from multiple people Planted actors or stimulus crowds of different size to stare up at a window across the street Passersby are filmed to record reactions--stop and stare/glance up Crowd of 1: 4% of pedestrians stopped Crowd of 15: 40% stopped, 86% glanced up Crowd of 5 induced almost the same effect as 15+!
Passersby were influenced in deciding to copy a behavior by the size of the crowd exhibiting itPhoto by David Sim
Stanley connected by an average of six steps
Six Degrees of Separation people Milgram experiment showing that
A citizen in Nebraska was instructed to mail a letter to someone who they thought would know a particular business man in Boston The goal was to measure the number of steps for the letter to reach the business man On average, required six steps
Replicated on global scale with same results! Its a small world after all
Three Degrees of Influence 3 degrees The influence of actions ripples through networks(to and from your friends friends friends)You are affected by people you dont even know! Influence dissipates after 3 degrees because: -Intrinsic decay: corruption of information (like the game telephone) -Network Instability: social ties become unstable at 4+ degrees of separation -Evolutionary Purpose: we evolved in small groups where everyone was connected by 3 degrees or lessPhoto by Taro Taylor
Three Degrees of InfluenceIf we are connected to everyone by 6 degrees and influence those up to 3 degrees, then we can reach halfway to the whole world!
Photo by Wonderworks, Flikr