-
Notifications
You must be signed in to change notification settings - Fork 2
/
Copy pathModel 1.nlogo
1484 lines (1353 loc) · 46.2 KB
/
Model 1.nlogo
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
;; agents have a probablity to reproduce and a strategy
turtles-own [ ptr cooperate-with-same? cooperate-with-different? wealth tag]
globals [
;; the remaining variables support the replication of published experiments
meet ;; how many interactions occurred this turn
meet-agg ;; how many interactions occurred through the run
last100meet ;; meet for the last 100 ticks
meetown ;; what number of individuals met someone of their own color this turn
meetown-agg ;; what number of individuals met someone of their own color throughout the run
last100meetown ;; meetown for the last 100 ticks
meetother ;; what number of individuals met someone of a different color this turn
meetother-agg ;; what number of individuals met someone of a different color throughout the run
last100meetother ;; meetother for the last 100 ticks
coopown ;; how many interactions this turn were cooperating with the same color
coopown-agg ;; how many interactions throughout the run were cooperating with the same color
last100coopown ;; coopown for the last 100 ticks
coopother ;; how many interactions this turn were cooperating with a different color
coopother-agg ;; how many interactions throughout the run were cooperating with a different color
defother ;; how many interactions this turn were defecting with a different color
defother-agg ;; how many interactions throughout the run were defecting with a different color
last100defother ;; defother for the last 100 ticks
last100cc ;; how many cooperate-cooperate genotypes have there been in the last 100 ticks
last100cd ;; how many cooperate-defect genotypes have there been in the last 100 ticks
last100dc ;; how many defect-cooperate genotypes have there been in the last 100 ticks
last100dd ;; how many defect-defect genotypes have there been in the last 100 ticks
last100consist-ethno ;; how many interactions consistent with ethnocentrism in the last 100 ticks
last100coop ;; how many interactions have been cooperation in the last 100 ticks
me
you
mylist
percentile75
percentile50
percentile25
]
to setup-empty
clear-all
initialize-variables
reset-ticks
end
;; creates a world with an agent on each patch
to setup-full
clear-all
initialize-variables
ask patches [ create-turtle ]
reset-ticks
end
to initialize-variables
;; initialize all the variables
set meetown 0
set meetown-agg 0
set meet 0
set meet-agg 0
set coopown 0
set coopown-agg 0
set defother 0
set defother-agg 0
set meetother 0
set meetother-agg 0
set coopother 0
set coopother-agg 0
set last100dd []
set last100cd []
set last100cc []
set last100dc []
set last100coopown []
set last100defother []
set last100consist-ethno []
set last100meetown []
set last100meetother []
set last100meet []
set last100coop []
set me 0
set you 0
set mylist []
set percentile75 0
set percentile50 0
set percentile25 0
end
;; creates a new agent in the world
to create-turtle ;; patch procedure
sprout 1 [
set wealth random 100
if wealth > 75 [ set color blue]
if wealth <= 75 and wealth > 50 [ set color green ]
if wealth <= 50 and wealth > 25 [ set color yellow ]
if wealth <= 25 [ set color red ]
set tag wealth
;; determine the strategy for interacting with someone of the same color
set cooperate-with-same? (random-float 1.0 < immigrant-chance-cooperate-with-same)
;; determine the strategy for interacting with someone of a different color
set cooperate-with-different? (random-float 1.0 < immigrant-chance-cooperate-with-different)
;; change the shape of the agent on the basis of the strategy
update-shape
]
end
to-report random-color
report one-of [red blue yellow green]
end
;; this is used to clear stats that change between each tick
to clear-stats
set meetown 0
set meet 0
set coopown 0
set defother 0
set meetother 0
set coopother 0
end
;; the main routine
to go
clear-stats ;; clear the turn based stats
;;immigrate ;; new agents immigrate into the world
;; reset the probability to reproduce
;;ask turtles [ set ptr initial-ptr ]
;; have all of the agents interact with other agents if they can
ask turtles [ interact ]
;; transact and then update your location
;;ask turtles with [ wealth > 0 ] [ transact ]
;; now they reproduce
;;ask turtles [ reproduce ]
;;death ;; kill some of the agents
update-stats ;; update the states for the aggregate and last 100 ticks
recolor-turtles
tick
end
;; random individuals enter the world on empty cells
;;to immigrate
;;let empty-patches patches with [not any? turtles-here]
;; we can't have more immigrants than there are empty patches
;;let how-many min list immigrants-per-day (count empty-patches)
;;ask n-of how-many empty-patches [ create-turtle ]
;;end
to transact
;; give a dollar to another turtle
;;set wealth wealth + 1
;;ask one-of other turtles [ set wealth wealth + 1 ]
set me wealth
ask one-of other turtles [set you wealth]
set wealth wealth + you * exchange_rate
ask one-of other turtles [set wealth wealth + me * exchange_rate]
end
to interact ;; turtle procedure
;; interact with Von Neumann neighborhood
ask turtles-on neighbors4 [
;; the commands inside the ASK are written from the point of view
;; of the agent being interacted with. To refer back to the agent
;; that initiated the interaction, we use the MYSELF primitive.
set meet meet + 1
set meet-agg meet-agg + 1
;; do one thing if the individual interacting is the same color as me
if color = [color] of myself [
;; record the fact the agent met someone of the own color
set meetown meetown + 1
set meetown-agg meetown-agg + 1
;; if I cooperate then I reduce my PTR and increase my neighbors
if [cooperate-with-same?] of myself [
set coopown coopown + 1
set coopown-agg coopown-agg + 1
transact
;;ask myself [ set wealth wealth + ( ask wealth of neighbors * exchange_rate) ];; Change these lines
;; I was trying to change this line to set personal wealth to personal wealth + neighbors wealth * exchange rate
;; This code will be the exact same in the next section
;;set ptr ptr + gain-of-receiving
]
]
;; if we are different colors we take a different strategy
if color != [color] of myself [
;; record stats on encounters
set meetother meetother + 1
set meetother-agg meetother-agg + 1
;; if we cooperate with different colors then reduce our PTR and increase our neighbors
ifelse [cooperate-with-different?] of myself [
set coopother coopother + 1
set coopother-agg coopother-agg + 1
transact
;; ask myself [ set wealth wealth * exchange_rate ];;Change these lines
;;set ptr ptr + gain-of-receiving
]
[
set defother defother + 1
set defother-agg defother-agg + 1
]
]
]
end
;; use PTR to determine if the agent gets to reproduce
;;to reproduce ;; turtle procedure
;; if a random variable is less than the PTR the agent can reproduce
;; if random-float 1.0 < ptr [
;; find an empty location to reproduce into
;; let destination one-of neighbors4 with [not any? turtles-here]
;;if destination != nobody [
;; if the location exists hatch a copy of the current turtle in the new location
;; but mutate the child
;;hatch 1 [
;;move-to destination
;;mutate
;; ]
;; ]
;; ]
;;end
;; modify the children of agents according to the mutation rate
;;to mutate ;; turtle procedure
;; mutate the color
;;if random-float 1.0 < mutation-rate [
;;let old-color color
;;while [color = old-color]
;;[ set color random-color ]
;;]
;; mutate the strategy flags;
;; use NOT to toggle the flag
;;if random-float 1.0 < mutation-rate [
;;set cooperate-with-same? not cooperate-with-same?
;;]
;;if random-float 1.0 < mutation-rate [
;;set cooperate-with-different? not cooperate-with-different?
;;]
;; make sure the shape of the agent reflects its strategy
;;update-shape
;;end
;;to death
;; check to see if a random variable is less than the death rate for each agent
;;ask turtles [
;;if random-float 1.0 < death-rate [ die ]
;;]
;;end
;; make sure the shape matches the strategy
to update-shape
;; if the agent cooperates with same they are a circle
ifelse cooperate-with-same? [
ifelse cooperate-with-different?
[ set shape "circle" ] ;; filled in circle (altruist)
[ set shape "circle 2" ] ;; empty circle (ethnocentric)
]
;; if the agent doesn't cooperate with same they are a square
[
ifelse cooperate-with-different?
[ set shape "square" ] ;; filled in square (cosmopolitan)
[ set shape "square 2" ] ;; empty square (egoist)
]
end
;;to recolor-turtles
;;let max-wealth max [wealth] of turtles
;;ask turtles
;;[ ifelse (wealth <= (max-wealth * 1 / 4))
;;[ set color red ]
;;[ ifelse (wealth <= (max-wealth * 1 / 2))
;;[ set color yellow ]
;;[ ifelse (wealth <= (max-wealth * 3 / 4))
;;[set color green]
;;[set color blue ] ] ] ]
;;to recolor-turtles
;;ask turtles
;;[ifelse (wealth >= sum [ wealth ] of max-n-of (count turtles * 0.25) turtles [ wealth])
;;[set color blue]
;;[ifelse (wealth <= sum [ wealth ] of max-n-of (count turtles * 0.25) turtles [ wealth] and wealth > sum [ wealth ] of max-n-of (count turtles * 0.50) turtles [ wealth])
;;[set color green]
;;[ifelse (wealth <= sum [ wealth ] of max-n-of (count turtles * 0.50) turtles [ wealth] and wealth > sum [ wealth ] of min-n-of (count turtles * 0.25) turtles [ wealth])
;; [set color yellow]
;; [else (wealth <= sum [ wealth ] of min-n-of (count turtles * 0.25) turtles [ wealth])
;; [set color red] ] ] ] ]
to recolor-turtles
set mylist sort-on[wealth]turtles
set percentile75 [wealth] of item (0.75 * length(mylist)) mylist
set percentile50 [wealth] of item (0.50 * length(mylist)) mylist
set percentile25 [wealth] of item (0.25 * length(mylist)) mylist
ask turtles
[ifelse (wealth >= percentile75)
[set color blue]
[ifelse (wealth < percentile75 and wealth >= percentile50)
[set color green]
[ifelse (wealth < percentile50 and wealth >= percentile25)
[set color yellow]
[set color red] ] ] ]
end
;; this routine calculates a moving average of some stats over the last 100 ticks
to update-stats
;;set last100dd shorten lput (count turtles with [shape = "square 2"]) last100dd
;;set last100cc shorten lput (count turtles with [shape = "circle"]) last100cc
;;set last100cd shorten lput (count turtles with [shape = "circle 2"]) last100cd
;;set last100dc shorten lput (count turtles with [shape = "square"]) last100dc
set last100coopown shorten lput coopown last100coopown
set last100defother shorten lput defother last100defother
set last100meetown shorten lput meetown last100meetown
set last100coop shorten lput (coopown + coopother) last100coop
set last100meet shorten lput meet last100meet
set last100meetother shorten lput meetother last100meetother
end
;; this is used to keep all of the last100 lists the right length
to-report shorten [the-list]
ifelse length the-list > 100
[ report butfirst the-list ]
[ report the-list ]
end
;; these are used in the BehaviorSpace experiments
to-report meetown-percent
report meetown / max list 1 meet
end
to-report meetown-agg-percent
report meetown-agg / max list 1 meet-agg
end
to-report coopown-percent
report coopown / max list 1 meetown
end
to-report coopown-agg-percent
report coopown-agg / max list 1 meetown-agg
end
to-report defother-percent
report defother / max list 1 meetother
end
to-report defother-agg-percent
report defother-agg / max list 1 meetother-agg
end
to-report consist-ethno-percent
report (defother + coopown) / (max list 1 meet )
end
to-report consist-ethno-agg-percent
report (defother-agg + coopown-agg) / (max list 1 meet-agg )
end
to-report coop-percent
report (coopown + coopother) / (max list 1 meet )
end
to-report coop-agg-percent
report (coopown-agg + coopother-agg) / (max list 1 meet-agg)
end
to-report cc-count
report sum last100cc / max list 1 length last100cc
end
to-report cd-count
report sum last100cd / max list 1 length last100cd
end
to-report dc-count
report sum last100dc / max list 1 length last100dc
end
to-report dd-count
report sum last100dd / max list 1 length last100dd
end
to-report cc-percent
report cc-count / (max list 1 (cc-count + cd-count + dc-count + dd-count))
end
to-report cd-percent
report cd-count / (max list 1 (cc-count + cd-count + dc-count + dd-count))
end
to-report dc-percent
report dc-count / (max list 1 (cc-count + cd-count + dc-count + dd-count))
end
to-report dd-percent
report dd-count / (max list 1 (cc-count + cd-count + dc-count + dd-count))
end
to-report last100coopown-percent
report sum last100coopown / max list 1 sum last100meetown
end
to-report last100defother-percent
report sum last100defother / max list 1 sum last100meetother
end
to-report last100consist-ethno-percent
report (sum last100defother + sum last100coopown) / max list 1 sum last100meet
end
to-report last100meetown-percent
report sum last100meetown / max list 1 sum last100meet
end
to-report last100coop-percent
report sum last100coop / max list 1 sum last100meet
end
; Copyright 2003 Uri Wilensky.
; See Info tab for full copyright and license.
@#$#@#$#@
GRAPHICS-WINDOW
323
10
582
270
-1
-1
9.67
1
10
1
1
1
0
1
1
1
0
25
0
25
0
0
1
ticks
30.0
SLIDER
5
150
171
183
mutation-rate
mutation-rate
0.0
1.0
0.005
0.0010
1
NIL
HORIZONTAL
SLIDER
5
184
171
217
death-rate
death-rate
0.0
1.0
0.1
0.05
1
NIL
HORIZONTAL
SLIDER
5
218
171
251
immigrants-per-day
immigrants-per-day
0.0
100.0
1.0
1.0
1
NIL
HORIZONTAL
SLIDER
172
150
318
183
initial-PTR
initial-PTR
0.0
1.0
0.2
0.01
1
NIL
HORIZONTAL
SLIDER
172
184
318
217
cost-of-giving
cost-of-giving
0.0
1.0
0.01
0.01
1
NIL
HORIZONTAL
SLIDER
172
218
318
251
gain-of-receiving
gain-of-receiving
0.0
1.0
0.03
0.01
1
NIL
HORIZONTAL
BUTTON
20
29
128
62
setup empty
setup-empty
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
BUTTON
222
29
295
62
NIL
go
T
1
T
OBSERVER
NIL
NIL
NIL
NIL
0
PLOT
6
323
318
525
Strategy Counts
time
count
0.0
10.0
0.0
1.0
true
true
"" ""
PENS
"CC" 1.0 0 -10899396 true "" "plotxy ticks count turtles with [shape = \"circle\"]"
"CD" 1.0 0 -2674135 true "" "plotxy ticks count turtles with [shape = \"circle 2\"]"
"DC" 1.0 0 -4079321 true "" "plotxy ticks count turtles with [shape = \"square\"]"
"DD" 1.0 0 -16777216 true "" "plotxy ticks count turtles with [shape = \"square 2\"]"
BUTTON
130
29
219
62
setup full
setup-full
NIL
1
T
OBSERVER
NIL
NIL
NIL
NIL
1
SLIDER
5
252
318
285
immigrant-chance-cooperate-with-same
immigrant-chance-cooperate-with-same
0.0
1.0
0.26
0.01
1
NIL
HORIZONTAL
SLIDER
5
286
318
319
immigrant-chance-cooperate-with-different
immigrant-chance-cooperate-with-different
0.0
1.0
0.5
0.01
1
NIL
HORIZONTAL
SLIDER
30
91
202
124
exchange_rate
exchange_rate
0.01
1
0.01
0.01
1
NIL
HORIZONTAL
@#$#@#$#@
## WHAT IS IT?
This model, due to Robert Axelrod and Ross A. Hammond, suggests that "ethnocentric" behavior can evolve under a wide variety of conditions, even when there are no native "ethnocentrics" and no way to differentiate between agent types. Agents compete for limited space via Prisoner Dilemma's type interactions. "Ethnocentric" agents treat agents within their group more beneficially than those outside their group. The model includes a mechanism for inheritance (genetic or cultural) of strategies.
## HOW IT WORKS
Each agent has three traits: a) color, b) whether they cooperate with same colored agents, and c) whether they cooperate with different colored agents. An "ethnocentric" agent is one which cooperates with same colored agents, but does not cooperate with different colored agents. An "altruist" cooperates with all agents, while an "egoist" cooperates with no one. A "cosmopolitan" cooperates with agents of a different color but not of their own color.
At each time step, the following events occur:
1. Up to IMMIGRANTS-PER-DAY, new agents appear in random locations with random traits.
2. Agents start with an INITIAL-PTR (Potential-To-Reproduce) chance of reproducing. Each pair of adjacent agents interact in a one-move Prisoner's Dilemma in which each chooses whether or not to help the other. They either gain, or lose some of their potential to reproduce.
3. In random order, each agent is given a chance to reproduce. Offspring have the same traits as their parents, with a MUTATION-RATE chance of each trait mutating. Agents are only allowed to reproduce if there is an empty space next to them. Each agent's birth-rate is reset to the INITIAL-PTR.
4. The agent has a DEATH-RATE chance of dying, making room for future offspring and immigrants.
## HOW TO USE IT
To prepare the simulation for a new run, press SETUP EMPTY. Press GO to start the simulation running, press GO again to stop it.
SETUP FULL will allow you to start with a full world of random agents.
COST-OF-GIVING indicates how much it costs an agent to cooperate with another agent.
GAIN-OF-RECEIVING indicates how much an agent gains if another agent cooperates with them.
IMMIGRANT-CHANCE-COOPERATE-WITH-SAME indicates the probability that an immigrating agent will have the COOPERATE-WITH-SAME? variable set to true.
IMMIGRANT-CHANCE-COOPERATE-WITH-DIFFERENT indicates the probability that an immigrating agent will have the COOPERATE-WITH-DIFFERENT? variable set to true.
The STRATEGY COUNTS plot tracks the number of agents that utilize a given cooperation strategy:
CC --- People who cooperate with everyone
CD --- People who cooperate only with people of the same type
DD --- People who do not cooperate with anyone
DC --- People who only cooperate with people of different types
## THINGS TO NOTICE
Agents appear as circles if they cooperate with the same color. They are filled in if they also cooperate with a different color (altruists) or empty if they do not (ethnocentrics). Agents are squares if they do not cooperate with the same color. The agents are filled in if they cooperate with a different color (cosmopolitans) or empty if they do not (egoists).
Observe the interaction along the edge of a group of ethnocentric agents, and non-ethnocentric agents. What behaviors do you see? Is one more stable? Does one expand into the other group?
Observer the STRATEGY COUNTS plot. Does one strategy occur more than others? What happens when we change the model?
## THINGS TO TRY
Set the IMMIGRANT-CHANCE-COOPERATE sliders both to 1.0. This means there are only altruists created. Do ethnocentrics and other strategies ever evolve? Do they ever out compete the altruists?
Change the values of COST-OF-GIVING and GAIN-OF-RECEIVING and observe the effects on the model and the level of ethnocentricity.
This model comes with a group of BehaviorSpace experiments defined. You can access them by choosing BehaviorSpace on the Tools menu. These are the original experiments that Axelrod and Hammond ran to test the robustness of this model. These experiments vary lots of parameters like the size of the world, IMMIGRANTS-PER-DAY and COST-OF-GIVING. These experiments are detailed at http://www-personal.umich.edu/~axe/Shared_Files/Axelrod.Hammond/index.htm
## EXTENDING THE MODEL
Add more colors to the model. Does the behavior change?
Make some patches richer than others, so that agents on them have a higher chance of reproducing. Distribute this advantage across the world in different ways such as randomly, in blobs, or in quarters.
Tag patches with a color. distribute the colors across the world in different ways: blobs, randomly, in discrete quarters. Agents use the patch color under other agents to determine whether to cooperate with them or not.
## NETLOGO FEATURES
To ensure fairness, the agents should run in random order. Agentsets in NetLogo are always in random order, so no extra code is needed to achieve this.
## RELATED MODELS
* Segregation
* PD Basic
* Ethnocentrism - Alternative Visualization
## CREDITS AND REFERENCES
This model is a NetLogo version of the ethnocentrism model presented by Robert Axelrod at Northwestern University at the NICO (Northwestern Institute on Complex Systems) conference on October 25th, 2003.
See also Ross A. Hammond and Robert Axelrod, The Evolution of Ethnocentrism, http://www-personal.umich.edu/~axe/research/AxHamm_Ethno.pdf
## HOW TO CITE
If you mention this model or the NetLogo software in a publication, we ask that you include the citations below.
For the model itself:
* Wilensky, U. (2003). NetLogo Ethnocentrism model. http://ccl.northwestern.edu/netlogo/models/Ethnocentrism. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
Please cite the NetLogo software as:
* Wilensky, U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.
## COPYRIGHT AND LICENSE
Copyright 2003 Uri Wilensky.
![CC BY-NC-SA 3.0](http://ccl.northwestern.edu/images/creativecommons/byncsa.png)
This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-sa/3.0/ or send a letter to Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
Commercial licenses are also available. To inquire about commercial licenses, please contact Uri Wilensky at uri@northwestern.edu.
This model was created as part of the projects: PARTICIPATORY SIMULATIONS: NETWORK-BASED DESIGN FOR SYSTEMS LEARNING IN CLASSROOMS and/or INTEGRATED SIMULATION AND MODELING ENVIRONMENT. The project gratefully acknowledges the support of the National Science Foundation (REPP & ROLE programs) -- grant numbers REC #9814682 and REC-0126227.
<!-- 2003 -->
@#$#@#$#@
default
true
0
Polygon -7500403 true true 150 5 40 250 150 205 260 250
airplane
true
0
Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15
arrow
true
0
Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150
box
false
0
Polygon -7500403 true true 150 285 285 225 285 75 150 135
Polygon -7500403 true true 150 135 15 75 150 15 285 75
Polygon -7500403 true true 15 75 15 225 150 285 150 135
Line -16777216 false 150 285 150 135
Line -16777216 false 150 135 15 75
Line -16777216 false 150 135 285 75
bug
true
0
Circle -7500403 true true 96 182 108
Circle -7500403 true true 110 127 80
Circle -7500403 true true 110 75 80
Line -7500403 true 150 100 80 30
Line -7500403 true 150 100 220 30
butterfly
true
0
Polygon -7500403 true true 150 165 209 199 225 225 225 255 195 270 165 255 150 240
Polygon -7500403 true true 150 165 89 198 75 225 75 255 105 270 135 255 150 240
Polygon -7500403 true true 139 148 100 105 55 90 25 90 10 105 10 135 25 180 40 195 85 194 139 163
Polygon -7500403 true true 162 150 200 105 245 90 275 90 290 105 290 135 275 180 260 195 215 195 162 165
Polygon -16777216 true false 150 255 135 225 120 150 135 120 150 105 165 120 180 150 165 225
Circle -16777216 true false 135 90 30
Line -16777216 false 150 105 195 60
Line -16777216 false 150 105 105 60
car
false
0
Polygon -7500403 true true 300 180 279 164 261 144 240 135 226 132 213 106 203 84 185 63 159 50 135 50 75 60 0 150 0 165 0 225 300 225 300 180
Circle -16777216 true false 180 180 90
Circle -16777216 true false 30 180 90
Polygon -16777216 true false 162 80 132 78 134 135 209 135 194 105 189 96 180 89
Circle -7500403 true true 47 195 58
Circle -7500403 true true 195 195 58
circle
false
0
Circle -7500403 true true 0 0 300
circle 2
false
0
Circle -7500403 true true 0 0 300
Circle -16777216 true false 30 30 240
cow
false
0
Polygon -7500403 true true 200 193 197 249 179 249 177 196 166 187 140 189 93 191 78 179 72 211 49 209 48 181 37 149 25 120 25 89 45 72 103 84 179 75 198 76 252 64 272 81 293 103 285 121 255 121 242 118 224 167
Polygon -7500403 true true 73 210 86 251 62 249 48 208
Polygon -7500403 true true 25 114 16 195 9 204 23 213 25 200 39 123
cylinder
false
0
Circle -7500403 true true 0 0 300
dot
false
0
Circle -7500403 true true 90 90 120
face happy
false
0
Circle -7500403 true true 8 8 285
Circle -16777216 true false 60 75 60
Circle -16777216 true false 180 75 60
Polygon -16777216 true false 150 255 90 239 62 213 47 191 67 179 90 203 109 218 150 225 192 218 210 203 227 181 251 194 236 217 212 240
face neutral
false
0
Circle -7500403 true true 8 7 285
Circle -16777216 true false 60 75 60
Circle -16777216 true false 180 75 60
Rectangle -16777216 true false 60 195 240 225
face sad
false
0
Circle -7500403 true true 8 8 285
Circle -16777216 true false 60 75 60
Circle -16777216 true false 180 75 60
Polygon -16777216 true false 150 168 90 184 62 210 47 232 67 244 90 220 109 205 150 198 192 205 210 220 227 242 251 229 236 206 212 183
fish
false
0
Polygon -1 true false 44 131 21 87 15 86 0 120 15 150 0 180 13 214 20 212 45 166
Polygon -1 true false 135 195 119 235 95 218 76 210 46 204 60 165
Polygon -1 true false 75 45 83 77 71 103 86 114 166 78 135 60
Polygon -7500403 true true 30 136 151 77 226 81 280 119 292 146 292 160 287 170 270 195 195 210 151 212 30 166
Circle -16777216 true false 215 106 30
flag
false
0
Rectangle -7500403 true true 60 15 75 300
Polygon -7500403 true true 90 150 270 90 90 30
Line -7500403 true 75 135 90 135
Line -7500403 true 75 45 90 45
flower
false
0
Polygon -10899396 true false 135 120 165 165 180 210 180 240 150 300 165 300 195 240 195 195 165 135
Circle -7500403 true true 85 132 38
Circle -7500403 true true 130 147 38
Circle -7500403 true true 192 85 38
Circle -7500403 true true 85 40 38
Circle -7500403 true true 177 40 38
Circle -7500403 true true 177 132 38
Circle -7500403 true true 70 85 38
Circle -7500403 true true 130 25 38
Circle -7500403 true true 96 51 108
Circle -16777216 true false 113 68 74
Polygon -10899396 true false 189 233 219 188 249 173 279 188 234 218
Polygon -10899396 true false 180 255 150 210 105 210 75 240 135 240
house
false
0
Rectangle -7500403 true true 45 120 255 285
Rectangle -16777216 true false 120 210 180 285
Polygon -7500403 true true 15 120 150 15 285 120
Line -16777216 false 30 120 270 120
leaf
false
0
Polygon -7500403 true true 150 210 135 195 120 210 60 210 30 195 60 180 60 165 15 135 30 120 15 105 40 104 45 90 60 90 90 105 105 120 120 120 105 60 120 60 135 30 150 15 165 30 180 60 195 60 180 120 195 120 210 105 240 90 255 90 263 104 285 105 270 120 285 135 240 165 240 180 270 195 240 210 180 210 165 195
Polygon -7500403 true true 135 195 135 240 120 255 105 255 105 285 135 285 165 240 165 195
line
true
0
Line -7500403 true 150 0 150 300
line half
true
0
Line -7500403 true 150 0 150 150
pentagon
false
0
Polygon -7500403 true true 150 15 15 120 60 285 240 285 285 120
person
false
0
Circle -7500403 true true 110 5 80
Polygon -7500403 true true 105 90 120 195 90 285 105 300 135 300 150 225 165 300 195 300 210 285 180 195 195 90
Rectangle -7500403 true true 127 79 172 94
Polygon -7500403 true true 195 90 240 150 225 180 165 105
Polygon -7500403 true true 105 90 60 150 75 180 135 105
plant
false
0
Rectangle -7500403 true true 135 90 165 300
Polygon -7500403 true true 135 255 90 210 45 195 75 255 135 285
Polygon -7500403 true true 165 255 210 210 255 195 225 255 165 285
Polygon -7500403 true true 135 180 90 135 45 120 75 180 135 210
Polygon -7500403 true true 165 180 165 210 225 180 255 120 210 135
Polygon -7500403 true true 135 105 90 60 45 45 75 105 135 135
Polygon -7500403 true true 165 105 165 135 225 105 255 45 210 60
Polygon -7500403 true true 135 90 120 45 150 15 180 45 165 90
square
false
0
Rectangle -7500403 true true 30 30 270 270
square 2
false
0
Rectangle -7500403 true true 30 30 270 270
Rectangle -16777216 true false 60 60 240 240
star
false
0
Polygon -7500403 true true 151 1 185 108 298 108 207 175 242 282 151 216 59 282 94 175 3 108 116 108
target
false
0
Circle -7500403 true true 0 0 300
Circle -16777216 true false 30 30 240
Circle -7500403 true true 60 60 180
Circle -16777216 true false 90 90 120
Circle -7500403 true true 120 120 60
tree
false
0
Circle -7500403 true true 118 3 94
Rectangle -6459832 true false 120 195 180 300
Circle -7500403 true true 65 21 108
Circle -7500403 true true 116 41 127
Circle -7500403 true true 45 90 120
Circle -7500403 true true 104 74 152
triangle
false
0
Polygon -7500403 true true 150 30 15 255 285 255
triangle 2
false
0
Polygon -7500403 true true 150 30 15 255 285 255
Polygon -16777216 true false 151 99 225 223 75 224
truck
false
0
Rectangle -7500403 true true 4 45 195 187
Polygon -7500403 true true 296 193 296 150 259 134 244 104 208 104 207 194
Rectangle -1 true false 195 60 195 105
Polygon -16777216 true false 238 112 252 141 219 141 218 112
Circle -16777216 true false 234 174 42
Rectangle -7500403 true true 181 185 214 194
Circle -16777216 true false 144 174 42
Circle -16777216 true false 24 174 42
Circle -7500403 false true 24 174 42
Circle -7500403 false true 144 174 42
Circle -7500403 false true 234 174 42
turtle
true
0
Polygon -10899396 true false 215 204 240 233 246 254 228 266 215 252 193 210
Polygon -10899396 true false 195 90 225 75 245 75 260 89 269 108 261 124 240 105 225 105 210 105
Polygon -10899396 true false 105 90 75 75 55 75 40 89 31 108 39 124 60 105 75 105 90 105
Polygon -10899396 true false 132 85 134 64 107 51 108 17 150 2 192 18 192 52 169 65 172 87
Polygon -10899396 true false 85 204 60 233 54 254 72 266 85 252 107 210