Modelling the Emergence of Possesion Norms using Memes

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Modelling the Emergence of Possesion Norms using
Memes

• By David Soto Sedano

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Introduction

• - Simulation of fundamental properties of social
  systems gt construct and improve theories.
• - To construct multi-agent systems poses
  difficulties found in human societies.
• - Mechanisms from human societies.
• - The agents have no internal reasoning capacity.

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Previous work

• - Concentrate in the emergence or not of a norm.
• - Effects of an explicity given norm
• (Coleman - Prisioners dilemma).
• - Axelrod (1986) gt norms game based on the
  prisioners dilemma
• Boldness
• Vengefulness
• - Conte / Castelfranchi (1995) gt how norms
  control and reduce agression and how they
  influence individual differences.
• - Normative reputation gt norm abiding or norm
  cicumventing
• - Conte/Castelfranchi are only valid for
  egalitarian predator-collector societies.
• - In the next simulation are studied the
  emergence and the effect of norms.

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Social Norms and Memes

• - Social norms are compulsory, accepted
  prescriptions for human actions.
• - Coleman (1990)
• - there must be the need for a norm
• - neccesary sanction the norm violation.
• - Evolutionary norm emergence
• Combined with memes (parts of cultural
  tradition, they may change during
  lifetime).
• - They model social norms using certain
  behaviours connected with some memes.
• - Sanctioning meme gt sanctioning behaviour.
• - A social norm is present ifan an agent society
  both behaviours are displayed by a sufficient
  port of the population.

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The Model - The Sugarscape Model

• - Goal (Epstein Axtell) to construct
  artificial societies that model certain
  characteristics of real societies.
• - Cells and agents have certain properties and
  execute certain rules.
• - A simulation run consist in a sequence of
  simulation steps.

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• The landscape is a 50x50 grid of single cells.
• The cells have a current sugar level and maximum
  sugar capacity wich ranges from 0 to 4.
• Not equal opportunity.
• Sugarscape Growback Rule Galpha
• In each simulation step, the sugar content of a
  cell grows by alpha units until it reaches the
  max. sugar capacity of the cell.
• Metabolism rate denotes the amount of sugar an
  agent uses up each step.

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Agent Movement Rule M

• Maximum age.
• Vision range.
• Vision range, metabolism rato or maximum age are
  integer, and dont change during the agents
  lifetime.
• Agent are only able to move to cells in their
  vision range which are not occupied by other
  agents.
• Agent Movement Rule M
• search unoccupied cells (vision range)
• if possible, choose the closest one
• go to this cell
• collect all the sugar in the cell.

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Agent Sex Rule S

• Interactivities between neighbours.
• Agents can reproduce.
• Agent Sex Rule S
• Select a neighbouring agent randomly
• if it is fertil, opposite sex, and one of them
  have an unoccupied neighbouring cell, create a
  new agent on this cell.
• If the sugar level is enough to reproduce again,
  and we can find another appropiate neighbour,
  repeat rule S.
• The new-born agents inherit the properties of
  their parents.
• Metabolism, vision, and max. age are inherited
  with a probability of 1/2.

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Cultural Tags and Memes

• Cultural Tags To simulate cultural traits that
  may change during an agents life time.
• Cultural Transmission Rule K
• Choose randomly one of each neighbours tags
• If the tag of the neighbour doent have hte same
  value as the tag of the current agent, set the
  neighbours tag to the same value as the current
  agents tag.
• Epstein and Axtell formation of cultural
  different groups and introduce rules for combat
  between these groups. (spice)
• Tags gt we call them now memes.

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Extension of the Sugarscape Model towards Norm
Simulation

• An agent in a specific cell can mark this cell if
  it has not already been marked before by a
  different agent. (vision range)
• The memes regulate the agents behaviour with
  respect to marked cells.
• Possesion meme
• Sanction meme
• The sanction meme regulates the behaviour
  regarding norm violation. (sanction gt decrease
  the sugar level).
• With memes, when the possesion is activated, the
  agents are less motivated to move near other
  agents, so we have to change the Movemente Rule M
  for the Movement Rule MS.

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Movement Rule MS

• - if current agent is not fertil, perform
  movement rule M
• - otherwise search all unoccupied cells in vision
  range neighbouring a fertile agent of the
  opposite sex
• - if no such cell is found, perform rule M,
  otherwise go to a cell with a maximum amount of
  sugar
• - if several such cells are present, choose the
  clotest one
• - collect all the sugar from the cell

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• We give to the agents a movement gene. If its
  active the agents perform rule MS, otherwise M.

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Cultural Transmission Rule K

• K works similar to k, but hier the cultural
  adoption of memes depends on the sugar level of
  both agents.
• Changes with respect to the Epstein Axtells
  model
• metabolism rate and vision range
• better control the conditions of the simulations
• interpre the result more easily
• multiply the cells sugar capacity.
• Cultural Transmission Rule K
• for each neighbouring agent select randomly one
  of his memes
• if the meme doesnt have the same value of meme
  set the meme of the agent with less sugar to the
  same meme value as that of the agent with more
  sugar.

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