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Emergent Movement
Group experiments in emergent properties from simple rules

by Lee Altenberg © 2000, 2003
http://dynamics.org/Altenberg/

Originally prepared for and implemented at the Short Courses on the Mathematics of Biological Complexity, University of Tennessee, Knoxville, October 1-4, 2000.

Experiments:

  1. Have everyone adopt the same movement rule, among the rules below.
  2. Have each person randomly pick a movement rule.
  3. Split the group into persons adopting specific selections of the rules.
  4. Do perturbations of the above after some kind of ``attractor'' has been approached.
    1. Have a single person change their rule.
    2. Add a new person to the group.
    3. Remove a person from the group.

Movement Rules:

  1. Single person target

    1. Pick one person and walk toward them.

    2. Pick one person. Move toward them if they are stationary. If they start to move, stop.

    3. Pick one person. Move toward them if they are stationary. If they are moving, move.

    4. Pick a person. Stand next to them on their right.

  2. Two person target

    1. Pick 2 people and walk to their midpoint.

    2. Pick a ``guardian'' and a ``foe''. Position yourself so that your guardian is halfway between you and your foe.

    3. Pick a ``guardian'' and a ``foe''. Stand by your guardian with your guardian between you and your foe.

    4. Pick 2 people and keep an equilateral triangle with them.

    5. Pick 2 (or n) people and go from one to the other back and forth.

    6. Pick 2 (or n) people. Start with one. Spin in the direction they are facing. When you see the second person, spin in the direction they are facing, etc.

    7. Pick 2 (or n) people. Start with one. Spin in the direction they are facing. If you make eye contact, stop moving.

    8. Pick 2 (or n) people. Start with one. Spin in the direction they are facing. Spin in the direction opposite to the way they are facing.

  3. Three person target

    1. Pick 3 people. Which ever 2 of them are closest together, go to the mid point between them.

    2. Pick 3 people. Which ever 2 of them are farthest apart, got to the mid point between them.

  4. Multiple person target

    1. Go to a person or cluster of people.
      1. If 1 person, grab onto them and keep moving;
      2. If 2 people, grab one. The other departs.
      3. If 3 people, stay with them to make 4 people.
      4. etc., odd, even, odd, even; or try binary fission.

    2. Divide the group into 2 visibly marked types.
      1. Type I attaches to others of Type I.
      2. Type II stays near, but never at (say always 5 feet away from) any others.
      3. People then mill about.

    3. Divide the group into 2 visibly marked types.
      1. If Type I is being pursued, they go towards a Type I.
      2. If Type I is not being pursued, they go away from the nearest Type II.
      3. Type II goes to Type I.

    4. Join the smallest cluster of people. If the cluster changes size before you get there, ignore this. Once you arrive at the cluster, survey the other clusters; if there is a smaller cluster than the one you are in, go to that cluster.
        Options:
      1. Remove one person from the group. Repeat the above, note any differences.
      2. Survey the clusters as you move, and change direction mid course if the cluster you were going to is not longer the smallest cluster.

    5. Pick n people:

      1. Go from one to the next in a cycle.

      2. Start with one. Spin in the direction they are facing. When you see the second person, spin in the direction they are facing, etc.

      3. Start with one. Spin in the direction they are facing. If you make eye contact, stop moving.

      4. Start with one. Spin in the direction opposite to the way they are facing.

Modifiers:

  1. Divide the group into those who will move quickly and those who will move slowly.

The Space of Variations:

State variables:

  1. Number of persons determining the movement.
  2. Stationary vs. moving
    1. Moving toward vs. moving away
    2. Rotation vs. translation movement.
  3. Attraction vs. repulsion
  4. Location relative to you and the persons.
  5. Location relative to the persons.
  6. Face position.
  7. Eye position.
  8. History of movement.

Response of the Subject:

  1. Move
    1. To a point
    2. Away from a point
    3. Rotate in a direction
  2. Stop