10 th international conference “describing complex systems – decos” zadar, croatia, september...

10th International Conference “Describing Complex Systems – DECOS” Zadar, Croatia, September 4-6, 2008

Agent-based simulation of ethnic prejudice transmission using Entorama tool

Armano SrbljinovićMinistry of Defence – Institute for Research and Development of Defence Systems, Zagreb, Croatia

Vjekoslav AfrićFaculty of Humanities and Social Sciences University of Zagreb, Croatia

Branimir ČačeFaculty of Mechanical Engineering and Naval Architecture University of Zagreb, Croatia


Outline

• Theoretical background• Research hypotheses• High-level description of the model• Expected support from the model to the

hypotheses• Brief demonstration of the model using Entorama

Srbljinović, Afrić, Čače: Agent-based simulation of ethnic prejudice transmission using Entorama tool


Contact theory

• Relates contact between ethnic groups with prejudice within groups against members of other groups

• Gordon W. Allport: The Nature of Prejudice, 1954

• Thomas F. Pettigrew: Racially Separate or Together, 1971



The role of contact

• Contact amplifies or reduces effects of other factors present in situations in which contact occurs

Contact

Other factorsEthnic

prejudice



Unresolved issues of contact theory

• Does not specify:• Factors which might be influenced by contact• Mechanisms by which contact influences other factors

Contact

Other factorsEthnic

prejudice??



Theoretical hypotheses

• Economic context as “an additional factor” of the contact theory

(1) Economic context impacts ethnic prejudice (2) Contact moderates the influence of economic context

Contact

Economiccontext

Ethnic prejudice



Support to the hypotheses

• Empirical research (1)• Higher levels of economic development reduce the

likelihood of ethnic wars. (Sambanis, 2001)• The occurrence of a recession increases the probability

of internal conflict. (Blomberg and Hess, 2002)

• Contact theory itself (2)• Prejudice is lessened when the two groups:

• possess equal status, • seek common goals,• are cooperatively dependent upon each other,• interact with the positive support of authorities, laws, or

customs. (Pettigrew, 1971)



Support to the hypotheses

• Can we get additional support using an agent-based simulation model ?

Contact

Economiccontext

Ethnic prejudice

Agent-basedmodel



Reasons for using AB modelling

• Allows “playing with theories” without the need to interfere with real human subjects

• Particularly adequate for investigating micro-foundations of macro-phenomena

Micro-sociological foundations of group movements and conflicts have been neglected in political science, mainly because the proper theoretical tools to investigate the motives and thoughts of individuals, as well as the mechanisms and conditions of group mobilization, are lacking.

(Bollerup and Christensen, 1997)



Basic experimental design

Contact

Economiccontext

low

low

high

high

present present

notpresent

notpresent

• Dependent variable: ethnic prejudice• Independent variables: level of contact, presence

of economic context



Operationalization – the model

• 2 model settings:• Basic

• “Pure” prejudice transmission model• Corresponds to the absence of additional factors in

contact theory

• Extended• Prejudice transmission “embedded” in economic context• Economic context as additional factor

• 2 ethnic segregation patterns:• High segregation – corresponds to low contact• Low segregation – corresponds to high contact



Basic setting: prejudice transmission

• Agents of 2 ethnic groups: “blue” and “red”• Main attribute: prejudice level

• Low, medium, or high• Updated in each step by taking into account prejudice

levels in an agent’s “socializing circle”

• “Socializing circle” of an agent• A (fixed) group of other agents that an agent meets and

has an opportunity to “interact with”

• Interaction = observing the prejudice level of the other agent



Basic setting: prejudice transmission

• Probability of interaction with a given agent from the socializing circle depends on:• Ethnic membership of the given and the other agent• Strength of the norm of exclusion within the given agent’s

ethnic group• Prejudice level of the given and the other agent

• Strength of the norm of exclusion• Group parameter indicating the inclination of group members

to ostracize • Members of other groups• Members of the own group who are not willing to ostracize

members of other groups• Operationalized as a proportion of agents with high prejudice

level within an ethnic group



Extended setting: economic transactions

• Basic setting extended with a simple economy of exchange with unlimited resources (EoE-UR)

• Additional attribute: wealth• Each interaction accompanied with a simple

economic transaction which increases the wealth of the interacting agents by random amount between 0 and 1



Extended setting: economic transactions

• If the wealth of the given agent is approximately equal to the wealth of the agents from the socializing circle:• Prejudice level update is the same as in the basic

setting

• If the wealth of the given agent is significantly less than the wealth of the agents from the socializing circle:• The given agent is “dissatisfied” and “has an incentive

to try a new form of behaviour”• The new prejudice level of the given agent is chosen

randomly



Ethnic segregation patterns

• High segregation/low contact:• Blue agents spatially segregated from red agents

• Low segregation/high contact:• Blue agents spatially interspersed with red agents



Operational hypotheses

(H0) No significant effects of contact on ethnic prejudice in the absence of additional factors (basic setting)

(H1a) Negative effect of the EoE-UR on ethnic prejudice

(H1b) Amplifying effect of contact:Stronger negative effect of the EoE-UR on ethnic prejudice when the contact is high, than when the contact is low



Micro-explanation – (H0)

• In the segregated setting agents only meet more agents of the other colour, all other things being equal.

• Prejudice level depends mainly on the amount of prejudice in the surroundings:• If the proportions of prejudiced agents in the socializing

circles are approximately equal (irrespective of the prevailing colour), prejudice levels of agents will stay approximately equal.

Increased contact between groups will have no significant effect on prejudice.



Micro-explanation – (H1a)

• Wealth increases with interaction• Ideal-case assumption: unlimited resources, no

competition

• Less prejudiced agents are “more open” - have more opportunities for interaction

There is a clear incentive to become less prejudiced



Micro-explanation – (H1b)

• In the non-segregated setting, prejudiced agents interact less than in the segregated setting (less “brethren” in the surrounding)

Prejudiced agents become less wealthy in the non-segregated setting than in the segregated setting

There are more incentives to become less prejudiced in the non-segregated setting than in the segregated setting

Stronger negative effect of the EoE-UR on ethnic prejudice in the non-segregated setting (when the contact is high)



Control variables

• Initial proportion of prejudiced agents in the population

• Radius of the socializing circle• Population density • …



Implementation in Entorama



References

• Allport, Gordon W., 1954, The Nature of Prejudice, Addison-Wesley.• Axelrod, Robert, 1997, The Complexity of Cooperation: Agent-Based Models of Competition and

Collaboration, Princeton University Press.• Blomberg, S. Brock and Gregory D. Hess, 2002, The Temporal Links between Conflict and Economic

Activity, Journal of Conflict Resolution, 46(1), 74-90.• Bollerup, Søren Rinder and Christian Dons Christensen, 1997, Nationalism in Eastern Europe:

Causes and Consequences of the National Revivals and Conflicts in Late-Twentieth-Century Eastern Europe. Macmillan.

• Čače, Branimir, 2008, Entorama, http://www.entorama.com• Forbes, Hugh D., 1997, Ethnic Conflict: Commerce, Culture, and the Contact Hypothesis, Yale

University Press.• Grim, Patrick, Evan Selinger, William Braynen, Robert Rosenberger, Randy Au, Nancy Louie and John

Connolly, 2005, Modeling Prejudice Reduction: Spatialized Game Theory and the Contact Hypothesis, Public Affairs Quarterly, 19(2), 95-125.

• Hardin, Russell, 1997, One for All: The Logic of Group Conflict, 2nd edition, Princeton University Press.

• Pettigrew, Thomas F., 1971, Racially Separate or Together, McGraw-Hill.• Sambanis, Nicholas, 2001, Do Ethnic and Non-Ethnic Civil Wars Have the Same Causes? A

Theoretical and Empirical Inquiry (Part I), Journal of Conflict Resolution, 45(3), 259-282.• Srbljinović, Armano, 2008, The Transition of a Multiethnic Community from Segregation to Cultural

Pluralism, Doctoral thesis (in Croatian), University of Zagreb.


10 th international conference “describing complex systems – decos” zadar, croatia, september...

Documents

role of contact contact

croatia slide

ethnic groups

entorama tool slide

entorama srbljinovi

nature of prejudice

th international conference

contact mechanisms