Connected: Our Social Networks And How They Shape Our Lives #1

Chapter 1 In the Thick of It

The simplest network is a dyad or pair Dyads 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 Brigade Linear Mutual ties

Photo from FEMA

(flow in both directions)

The Telephone Tree Information is directional (inbound and outbound ties) Reduces number of steps Creates cascade effect

The Military Squad Tightly interconnected groups Two-way tie between all members of squad Squad is more intra-connected than inter-connected with other squads

Terms A 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)

Terms The 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 to The 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 network 2. We influence the density of interconnections between friends and family we introduce friends from separate groups to one another

We shape our network 3. We control how “central” we are within the social network Are you the life of the party?

Or the wall flower?

Transitivity Transitivity: 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

Influence Contagion: 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 person’s direct social ties)

What Are You Looking At? Stanley Milgram’s sidewalk experiment exploring the importance 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 it Photo by David Sim

Six Degrees of Separation Milgram experiment showing that people

Stanley connected by an average of six steps

are all

• 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! It’s a small world after all

Three Degrees of Influence The influence of actions ripples through networks 3 degrees (to and from your friends’ friends’ friends) You are affected by people you don’t 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 less Photo by Taro Taylor

Three Degrees of Influence If 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

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