1 / 34

Phenomenology of social dynamics

Santo Fortunato. Phenomenology of social dynamics. Outline. Prologue Building a phenomenology: 1) elections 2) collective opinion shifts Outlook. Physics. Society!. Sociophysics. From individuals that interact locally to collective behaviour and organization. Risky business!.

eve-alford
Download Presentation

Phenomenology of social dynamics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Santo Fortunato Phenomenology of social dynamics

  2. Outline • Prologue • Building a phenomenology: 1) elections 2) collective opinion shifts • Outlook

  3. Physics

  4. Society!

  5. Sociophysics From individuals that interact locally to collective behaviour and organization.

  6. Risky business! People are not atoms: their interactions are not reproducible! Necessary condition: the size of the social groups must be big (large scale behaviour) In this way, the phenomena won’t be much affected by individual features

  7. Interesting aspects for statistical physicists: • Large-scale regularities: scaling • Universal features • Microscopic origin of macroscopic behaviour Quantitative understanding!

  8. Focus: opinion dynamics • Opinion dynamics models explain if and when consensus is formed or not • Shall we content ourselves with such a qualitative description? • Is it possible to validate this approach?

  9. Building a phenomenologyof social dynamics • Elections • Collective opinion shifts Quantitative characterization of large scale social phenomena

  10. Elections • Large scale social phenomenon • Lots of available data

  11. Elections State elections in Brazil 1998 (Costa Filho et al., PRE, 1999) v = # votes received by a candidate Focus: distribution of v across all candidates 1/v behavior

  12. Elections in Brazil 2002 (Costa Filho et al., Physica A 2003) 1/v decay reproducible over the years

  13. Indian elections (González et al. IJMPC, 2004) • 1/v decay occurs in different countries • Is it universal?

  14. The 1/v behaviour is not universal!

  15. Problem: is it correct to put together candidates of different parties? Support for different parties wildly fluctuates!

  16. Position of parties is more or less known on relevant issues • Party is selected depending on the issues • Candidate to be voted is chosen depending on the existence of some form of direct/indirect contact with the voter → model!

  17. N = total votes for party Q = number of party candidates A new analysis (S.F. & C. Castellano, physics/0612140) Proportional elections with open lists Examples: Italy (1946-1992), Poland, Finland Distribution of votes for candidates within a party P(v,Q,N)

  18. Scaling I Only two independent variables! P(v,Q,N)=P*(v,N/Q)= P*(v,v0)

  19. Scaling II Only one independent variable! P(v,Q,N)=P*(v,N/Q)= F(vQ/N)!

  20. The scaling function is universal!

  21. The universal curve has a lognormal shape!

  22. Municipal elections display identical decay

  23. Conclusion of election analysis Same behaviour in different countries and years: the dynamics must be elementary!

  24. Collective opinion shifts Studied by Michard and Bouchaud (2004) Principle: imitation + social pressure lead to collective effects with rapid variations Examples: crowd panic, financial crashes, economic crisis, boom of new products, etc.

  25. A model Binary choices: Si=+1,-1 • each agent i has a personal opinion Φi, real in ]-∞,+∞[, distribution R(Φ) • public information: a field F(t) in ]-∞,+∞[ acting on all agents • social pressure: agent i is affected by “neighboring” agents, coupling Jij Three ingredients:

  26. Field F varies from -∞ to +∞, which O(F)? Random Field Ising Model at T=0 J. Sethna et al., Nature 410, 242 (2001)

  27. For J larger than a critical Jc, O(F) has a discontinuity at some Fc(J) (opinion swings)

  28. For J <~ Jc G(x) is universal, i.e. independent of R(Φ)

  29. h w Characteristic relation between height h and width w of the curve:

  30. O t Assumption: collective opinion shifts occur near criticality Expectation/hope: recovering the peak of G(x) from real data!

  31. Birth rates in Europe Drop in most European countries in the period 1950-2000

  32. Cell phones in Europe Total number of cell phones in use in various European countries in the last decade

  33. Outlook • The distribution of the number of votes received by candidates of the same party in proportional elections is universal! • Collective opinion shifts are characterized by a universal pattern of variation for the speed of change • Search for other regularities in data is necessary to create a “physical” phenomenology in social dynamics

More Related