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view/download model file: 1D Majority Game.nlogo
WHAT IS IT?
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This model presents a basic one-dimensional majority or plurality voting model. Agents live on a ring (so there are no 'edge effects') and can be one of two types: red or blue. In each step, agents change their state based upon the majority (or plurality) of their neighbors' states.
HOW TO USE IT
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Clicking SETUP fills the world with agents (one per patch) each with a randomly chosen color.
Clicking GO makes the turtles look at their neighbors and decide what color to become. All the agents look and change simultaneously, that, is, the model employs synchronous updating. Clicking STEP runs GO just once.
The RADIUS slider allows the user to set how far away in each direction the agents will look to collect information about other users' states. For example, if you set RADIUS to 3, each agent will look out to three cells in both directions for a total of six neighbors.
The USE-PLURALITY toggle switch allows the user to specifiy whether the decision rule is a "majority" rule or a "plurality" rule. If the USE-PLURALITY switch is on then each agent will convert to whichever color is most prominent among its neighbors.
If USE-PLURALITY is off, then the decision is based upon majority rule. The PERCENT-NEEDED slider determines the quorum, i.e. how many neighbors of a color are necessary make an agent change its color. At the lowest level (50%) the models runs a strict majority and at the maximum level (100%) unanimity is required.
The NUMBER_NEEDED monitor box lets the user know how many agents of a single color are required to convert each agent, given the provided RADIUS and PERCENT-NEEDED. Note that the actual number must be strictly greater than the number in this box (can you look at the code and answer why?).
THINGS TO NOTICE
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The colors start off very scattered. Notice that they form clusters after you run the model. Change the radius. Notice how that changes the cluster size (cluster size = the number of contiguous agents of the same color).
QUESTIONS
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1) What is the difference between a 50% majority rule and the plurality rule in this model?
2) Under each rule, what happens when an agent has equal numbers of neighbors with each color?
3) What behavior do you see when you set the percentage to 100%? Is this what you expect? Why are you getting this behavior? What can you do to get the behavior you expect?
THINGS TO TRY
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Ties are broken in certain ways. Can you change the code so that a different tie-breaking rule is used? How do you interpret your new rule?
CREDITS AND REFERENCES
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To refer to this model please use: Bramson, A and Scott Page (2005). NetLogo 1D Majority Game model. "http://bramson.net/academ/scottsnetlogo/1D Majority Game.html". Center for the Study of Complex Systems, University of Michigan, Ann Arbor, MI.