NetLogo User Community Models

(back to the NetLogo User Community Models)

Download If clicking does not initiate a download, try right clicking or control clicking and choosing "Save" or "Download". Try It in NetLogo Web

## WHAT IS IT?

The Social Impact Model is based on the psychological theory of Latané (1981). Latané introduced many ideas and concepts from complex systems theory into social psychology.
In this theory, opinion change depends on social impact.

See:
Lewenstein, M., Nowak, A., & Latané, B. (1992). Statistical mechanics of social impact. Physical Review A, 45(2), 763–776. https://doi.org/10.1103/PhysRevA.45.763

Holyst, J. A., Kacperski, K., & Schweitzer, F. (2001). Social impact models of opinion dynamics. In Annual Reviews of Computational Physics IX: Vol. Volume 9 (pp. 253–273). WORLD SCIENTIFIC. https://doi.org/10.1142/9789812811578_0005

## HOW IT WORKS

We represent the two possible spin states by the numbers +1 or -1. Spins of +1 are shown in light blue, spins of -1 are shown in dark blue.

The social impact is a function of the persuasiveness of opponents (connected agents with the opposite opinion), the supportiveness of supporters (with the same opinion), and the distance to these agents). All of these parameters have positive random values.
Lewenstein et al. (1992) present analytical mean-field solutions for fully connected networks.

## HOW TO USE IT

You can control the proportion of spins that start at +1 using the PROBABILITY-OF-SPIN-UP slider. If you want all spins to be +1, set this slider to 100%. If you want all spins to be -1, set it to 0%.

The random external field Hi can also be controlled with the slider. H is uniformly distributed between 0 and H-max.

Then press GO to watch the model run.

The magnetization of the system is the average (mean) of all the spins. The MAGNETIZATION monitor and plot show you the current magnetization and how it has varied so far over time.

## THINGS TO NOTICE

Without individual fields, the model ends up with an infinite number of stationary states, one of which is usually dominant.
In the presence of individual fields, some minority opinions can become metastable. These metastable opinions may persist for some time, but eventually, due to noise or other factors, they may suddenly shrink to smaller clusters. These smaller clusters can also persist for some time before shrinking again, and the process repeats itself, resulting in the staircase behavior.

## HOW TO CITE

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.


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 -->