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www.ingenio.upv.es. Simulating the Social Processes of Science Leiden| 9 April 2014. DIFFUSION OF SCIENTIFIC KNOWLEDGE: A PERCOLATION MODEL Elena M. Tur With P Zeppini and K Frenken. INGENIO [CSIC-UPV] Ciudad Politécnica de la Innovación | Edif 8E 4º Camino de Vera s/n
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www.ingenio.upv.es Simulating the Social Processes of Science Leiden| 9April 2014 DIFFUSION OF SCIENTIFIC KNOWLEDGE: A PERCOLATION MODEL Elena M. Tur With P Zeppini and K Frenken INGENIO [CSIC-UPV] Ciudad Politécnica de la Innovación | Edif 8E 4º Camino de Vera s/n 46022 Valencia tel +34 963 877 048 fax +34 963 877 991
Focus • How do social pressure and assortativityaffecttheprocess of diffusion? • How do theireffectinteractwiththe social networkstructure? • How do local effectsdictate global diffusionthroughtheoverallnetworkstructure? • Maincontribution: introducing social pressure in a model of diffusionwithdifferentnetworkstructures
Diffusion of ideas • Spread of rumors(Zanette, 2002) • Online spreading of behavior(Centola, 2010) • Opiniondynamics(Shao et al., 2009) • Paradigmshift in science(Brock and Durlauf, 1999) • How to approachtheproblem(Zeppini and Frenken, 2013) • Heterogeneityof agents • Externalities • Social network • Percolation(Solomon et al., 2000)
Percolation in a social network • : value of the idea • : minimumqualityrequirement of agent Agentadoptsthe idea at time if: • has notadoptedbefore • isinformed: a neighbor has adopted at time • iswilling to adopt:
Social network • Small world(Watts and Strogatz, 1998)Startingwith a regular lattice, with 𝑛 nodes and 𝑘 edges per node, rewire each edge at random with probability 𝑝 • High clusteringcoefficient, lowaveragepathlength
Percolationwithout social pressure • Upper bound to diffusion: 45º line (well-mixedpopulation) • Diffusionincreaseswith • Phasechanges: from a non-diffusion to a diffusionregime • Percolationthresholdsdecreasewith
Why social pressure? • Theunwilling to adopt can be persuaded • Network externalities: sharedlanguage, sharedexperiences, sharedbeliefs… • Increasingamount of evidence • Conformity(Asch,1958) • Weariness
Modelling social Pressure • : # neighbors of agentthathaveadopted at time • : social pressureintensity • isdecreasing in thenumber of adoptingneighbors • isdecreasing in the social pressureintensity • if • if
Parametersforthesimulations • agents • original neighbors in thesmallworldalgorithm • seedsor original adopters • time periods • runs of Monte Carlo simulations • iid • Social networks: lattice, smallworld, Poissonnetwork
People tend to be friends with similar people Assortativity
Modellingassortativity Most unwilling to adopt Most willing to adopt
Percolationwithassortativity • No criticaltransitionfrom non-diffusion to diffusion • Diffusionsizescaleslinearlywithdiffusionsize • No effect of thenetworkstructure (well-mixedpopulation)
Conclusions • Social pressurechangesthebehavior of thepercolationprocess: higherdiffusionsize, lowerpercolationthresholds • Theeffect of social pressureisdifferentfordifferentnetworkstructures: criticaltransition in smallworlds and lattices • With social pressure, clusteringbecomes beneficial fordiffusion: reduceddifferencesbetweennetworks • Assortativityremovestheeffect of thenetworkstructure: allbehave as a well-mixedpopulation • Assortativity can helporhamperdiffusiondependingonthesetting
Futurework and limitations • Other social networkstructures: scale-free networks(Barábasi and Albert, 1999) • Evolvingendogenous social network • Re-thinkthe social pressureimplementation: alwayspossitiveefffect? • Differentminimumqualityrequirementdistributions,
THANK YOU INGENIO [CSIC-UPV] Ciudad Politécnica de la Innovación | Edif 8E 4º Camino de Vera s/n 46022 Valencia tel +34 963 877 048 fax +34 963 877 991