THE EMERGENCE OF COLLECTIVE MEMORIES

Sungmin LeeVerónica RamenzoniPetter Holme

http://www.tp.umu.se/~holme/

Petter@DPG

I became interested in a science career

discrete mathematics

(my collaborator) Fredrik Liljeros decided to come here

complex network boom of early 00’s

(my office mate) MartinRosvall was invited

Narrative network / memory web

What is the topology of real narrative networks?How can we model the evolution of narrative networks / memory webs?How (much) can communication stabilize collective memories?What are the conditions for groups to form?How does the observations behave as a function of population size?

Outline

Empirical memory webSource material

Bearman, Moody, Faris, 2003. “Networks and History” Complexity 8:61–71.

Empirical memory webIndividual memory web 1

Bearman, Moody, Faris, 2003. “Networks and History” Complexity 8:61–71.

Empirical memory webIndividual memory web 2

Bearman, Moody, Faris, 2003. “Networks and History” Complexity 8:61–71.

Empirical memory webAggregate memory web

Bearman, Moody, Faris, 2003. “Networks and History” Complexity 8:61–71.

Empirical memory webDegree distribution

Empirical memory webCommunity structure

N agents with individual memory webs connected by a coevolving social networkAgents can learn about history from experience or communication.Closer friends are more likely to communicate & people who communicate often are closer friends.

Events / associative arcs remembered more strongly are more frequently discussed, and vice versa.

Events / associative arcs not talked about are gradually forgotten.

Model ingredients

Communication modelLearning dynamics

Example outputMemory overlap, Jaccard index of associative arcs

Model community structureNumber of groups

Model community structureMemories and social ties

15

Model community structureSize- & communication-rate scaling of the number of communities

Model community structureSize-scaling of the diversity regime

Model community structureSize-scaling of the number of groups

Narrative networks represent memory webs.Network modeling can be helpful to understand these quantitatively.An empirical narrative network shows skewed (in- and out-) degree distribution.Propose a communication model that shows the emergence of collective memories… and the formation of communities with strong internal connections and similar memory websThe number of communities is limited as a function of N

Summary

Petter

Vielen Dank!to all of you … from

Sungmin Verónica

http://www.tp.umu.se/~holme/

Empirical memory webClustering coefficient vs. degree

Empirical memory webDegree correlations

Communication modelCommunity structure

Communication modelErrors & misinterpretations

Model community structureWhy a peak in g?

Model community structureSize-scaling of the diversity regime