Presentation on theme: "Real-World Social Networks: Structure and Dynamics Bottom Up"— Presentation transcript:
1 Real-World Social Networks: Structure and Dynamics Bottom Up Robin DunbarInstitute of Cognitive &Evolutionary AnthropologyUniversity of Oxford
2 The Global Village?The Internet was based on the promise of enlarging your social world beyond the limits of the local villageBut does it actually work?
3 Does Technology Really Widen Your Horizons? The answer from Facebook’s own data seems to be: NoModal number of friends isYou may list 100s of friends, but you only talk to a fewWHY?Cameron Marlow web-blog3
4 To Begin at the Beginning…. Social Brain HypothesisAmong primates, social group size is determined by neocortex volumePredicted group size for humans is ~150[Dunbar’s Number]MonkeysApesDunbar (1992, 1993)
5 These all have mean sizes of 100-200 Twitter exchange contactsHuman Social NetworksGonçalves et al. (2011)Killworthet al (1984))Her 152 facebook friends….remembered foreverThese all have mean sizes ofNeolithic villages 6500 BCmilitary units (company) (N=10) 180* Hutterite communities (N=51) 107Nebraska Amish parishes (N=8) 113business organisation <200ideal church congregations <200Doomsday Book villagesC18th English villages* GoreTex Inc’s structureResearch sub-disciplines (N=13)Twitter personalised contactsSmall world experiments (N=2) 134Hunter-Gatherer communitiesXmas card networks“Reverse” Small WorldExperiments10010Hunter-Gatherer SocietiesDunbar (1993)Individual TribesSusyJ87Hill & Dunbar (2003)Xmas Card NetworksDunbar (1993, 2008)5
6 BUT….Human Networks are NOT Homogenous Less like this…..and more like this
7 Intimacy, Frequency and Trust Contact frequency differs across layersThere is a relationship between frequency of contact and intimacyHill & Dunbar (2003)7
8 The Fractal Periodicity of Human Group Sizes Sizes of Hunter-Gatherer GroupingsPeak at =5.4Slope 3Social Groupings Database [N=60]Hamilton et al (2007)Peak at =5.2Xmas Card DatabaseScaling ratio = exp(2π/)= 3.2 and 3.3Zhou, Sornette, Hill & Dunbar (2005)
9 The Friendship ShellsOur social worlds consist of layers of relationships…with 150 as the corenumber….and a scaling ratioof ~3…but extending beyondto 500, 1500IntensityEGO515501501500500
10 Intimacy, Frequency and Trust Mean contact frequency/dayMean Emotional ClosenessNetwork LayerSutcliffe et al (in press)Contact frequency and emotional closeness differs across layersThe layers appear to be quite discrete10
11 Network Structure Has Consequences HappyIntermediateUnhappyFowler et al (2008) Christakis (2007)Happiness and obesity are contagious…with effects up to three degrees away
12 Network Density is Important How well integrated your close network is influences your willingness to act altruisticallyEstimates of Fixed EffectsaParameterEstimateStd. ErrordftSig.Intercept2.350.60321.593.920.00AGREEABLENESS0.070.05283.661.470.14CONSCIENTIOUSNESS-0.090.06281.99-1.540.12YEARS_KNOWN0.039.81CONTACT_FREQUENCY0.340.0213.88AGREEABLENESS of TARGET0.090.017.34CONSCIENTIOUSNESS of TARGET7.76NETWORK DENSITY2.79Would you lend £5000?Curry & Dunbar (in press)
13 The Circles of Acquaintanceship Our networks are structured by more than just social closenessIntensityEGOOur networks are also split roughly equally between Family (kin) and Friends – two separate sub-networks that intersectFRIENDS5FAMILY1550150500
14 The Kinship Factor Our networks consist of about 50% kin [family] 80 close networksInnerlayersOuter layersSlope -1Our networks consist of about 50% kin [family]Kin are given priority over FriendsIf you come from a large extended family, you have fewer friends!250 complete networks-0.3 < slope< -0.9Total Kin
15 Blood is Thicker Than Water How much I value you relative to myselfWe value kin more than we value friends….. in any given layer of the networkWelfare Trade-off RatioFamilyFriendsNetwork LayerCurry & Dunbar (in press)
16 Stable Family, Fragile Friends StayKINMoveFriendsChange in Network LayerChange over TimemonthsKin FriendsRoberts & Dunbar (2011)
17 by change in activity score by change in contact frequency How to Prevent Relationships DecayingChange in Emotional Closeness months 0-9This is for friends only.Contact frequency here is based on self-report data, as I am still processing the detailed data from the phone bills.First graph – shows how change in emotional closeness is affected by change in the number of activities that ego and alter do together. So either decrease in activities from month 1 to month 9, no change, or doing more activities at month 9 than at beginning of study. For females, doesn’t seem to make much difference – decline in emotional closeness regardless of activities done together. For males, to offset decay in emotional closeness, physically doing things together seems to work well.This is the same graph for contact frequency – this includes both face-to-face and non face-to-face contact. So have decrease in contact frequency from month 1 to month 9, no change, or increase in frequency of communication from month 1 to month 9. For here, for females, it seems that to increase emotional closeness, communication rather than shared activities is the key, whereas for men, not such a strong effect of contact frequency.Supports previous research in this area – men’s friendships based around shared activities, whereas women's friendships based around communication and emotional intimacy. The advantage of this study is that we can look at how things like shared activities and communication dynamically affect relationships over the course of 18 months, and have very fine-grained data on communication patterns from the mobile bills.Roberts & Dunbar (2010)by change in activity scoreby change in contact frequency1717
18 What Makes Relationships Work? Primate social bonds seem to involve two distinct components:An emotionally intense component[=grooming]A cognitive component[=brain size + cognition]
19 The Limits to Intentionality... % CorrectA natural limit at 5th order intentionality:“I intend that you believe that Fred understands that we want him to be willing to [do something]…” [level 5]Intentionality Level
20 The Cognitive Limits to Sociality The Orders [or Levels] of Intentionality5th order seems to be the limit“I intend that you believe that Fred understands that we want him to be willing to [do something]…”Intentionality correlateswith size of support cliqueStiller & Dunbar (2007)Powell et al (2010)
21 Insights from Neuroimaging Powell et al (2010 & in press)In a stereological analysis of gross volume: best predictor of network size and intentional competence is orbitofrontal PFC volumeIn a fine-grained VBM (voxel) analysis: overlap of network size and intentional competence in the orbitovental PFCLewis et al (in press)2121
22 How Grooming Works endorphins are relaxing An experimental study with monkeysOpiates block social drive;Opiate-blockers enhance social driveSalendorphins are relaxingThey create a psycho-pharmacological environment for building trust?
23 Grooming Time in Humans? If we bonded our groups using the standard primate mechanism….we would have to spend 43% of the day grooming
24 Grooming Time in Humnas? In fact, we spend only 20% of our time in social interaction…..from a sample of 7 societies from Dundee to New GuineaHow do we bond our super-large communities?
25 Laughter as Virtual Touch? Change in Pain Threshold in Response to LaughterFactual vs Comedy VideosPain threshold as an assay for endorphin activationLaughter as a form of virtual grooming to bond more individuals?ComedyEdinburghFringeEdinburghFringeNeutralProcedure:pain testvideo/activitypain re-testDunbar et al (submitted)
26 Nothing Beats Reality….? Both perceived happiness AND laughter rates, F2F and Skype are better than all other mediaLaughter influences happiness[except in Skype]And may be more importantthan duration of interactionin promoting satisfactionSatisfaction RatingFrequency of LaughterSatisfaction RatingVladovik et al (submitted)NO YESLaughter
27 Synchony Ramps up the Endorphins Change in pain threshold before and after 45 mins rowing work-out on ergometers in the gym:Alone vs in a virtual boatAlone Group Alone Group
28 With Thanks to…. Funding: British Academy EPSRC ESRC Leverhulme Trust Comparative brains:Dr Susanne ShultzSocial Networks and behaviour:Dr Sam RobertsDr Tom PolletDr Oliver CurryDr Holly ArrowDr Jens BinderProf Alistair SutcliffeTatiana VlahovicDr Wei ZhouDr Russell HillProf Didier SornetteProf Mark van VugtRebecca Baron, Ellie Pearce and Anna FrangouNeuroimaging:Amy BirchJoanne PowellRachel BrowneDr Penny LewisProf Neil RobertsDr Marta García-FiñanaFunding:British AcademyEPSRCESRCLeverhulme TrustEU-FP7
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