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Computer-Mediated
Communication
Tournament Debrief
Coye Cheshire & Andrew Fiore
// May 25, 2017
Why Game Theory for mediated
communication?
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Game Theory
“Game theory is the systematic study of
interdependent rational choice. It may be
used to explain, to predict, and to evaluate
human behavior in contexts where the
outcome of action depends on what several
agents choose to do and where their choices
depend on what others choose to do.”
http://plato.stanford.edu/entries/game-ethics/
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Game Theory and Core Concepts
 Analytical vs. Behavioral
Game Theory
 Cooperative and NonCooperative Games
 Zero and Non-Zero Sum
Games
 One-Shot vs. Repeated
(example for cooperative game)
 Equilibria
 (i.e., Nash Equilibrium)
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Why the Prisoner’s Dilemma?
… demonstrates how communication
between individuals can significantly
alter “the best strategy” for solving a
problem where self interest might
otherwise lead to a deficient outcome.
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The Evolution of Cooperation
 Axelrod’s famous (1984)
tournament allowed individuals
to submit any strategy.
 All strategies played each
other in the tournament.
 The winner was one of the
shortest submissions, about 4
lines of code.
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The Simple Effectiveness of the Tit-for-Tat Strategy
 Tit-for-Tat: begin
with ‘cooperate’
and then do
whatever the
opponent did on
the last turn.
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Lessons from Tit-for-Tat
 Be nice
 It starts by cooperating. Most topscoring strategies do this.
 Be forgiving
 It quickly and happily returns to
cooperation without holding a grudge.
 Be able to retaliate
 It never allows defection to go
unpunished.
 Be clear
 It is predictable and easy to understand.
It pays to be predictable in non-zero sum
games.
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Considering the “Shadow of the Future”
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Is Tit-for-Tat Always the Answer?
 2-person repeated PD  N-person PD
Public Good
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Some common complaints…
 “Hey, isnt this rational
choice?”
 “This stuff explains the
problem, not the
solution!”
 “A theoretical tool
cannot explain real life,
right?”
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(Picture courtesy vismod.media.mit.edu)
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Revisiting our earlier question…Where does
this apply to CMC?
Del.ic.ious
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