Category Archives: chapter 4

4.7 flocking

A flocking model loosely based on ideas in

Czirók A and Vicsek T 2000 Collective behavior of interacting self-propelled particles. Physica A: Statistical Mechanics and its Applications, 281, 17–29.
Grégoire G, Chaté H and Tu Y 2003 Moving and staying together without a leader. Physica D: Nonlinear Phenomena, 181, 157–170.
Vicsek T, Czirók, A. A, Ben-Jacob E, Cohen I and Sochet O 1995 Novel type of phase transition in a system of self-driven particles. Physical Review Letters, 75, 1226–1229.

This model also includes various different implementations of the idea of ‘flock-mates’ which demonstrate the importance of basic spatial properties (in this case proximity or ‘neighbourhood’) in many spatial models.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.

4.5 Monkeys (or other animals) foraging in a heterogeneous environment

This model demonstrates how the distribution of resource availability in an environment can strongly influence the characteristics of movement motivated by exploitation of the resource. This model is loosely based on that described in

Boyer D, Ramos-Fernández G, Miramontes O, Mateos JL, Cocho G, Larralde H, Ramos H and Rojas F 2006 Scale-free foraging by primates emerges from their interaction with a complex environment. Proceedings of the Royal Society. Series B, 273, 1743-1750.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.

4.3 Simon’s satisficing forager model on a lattice

This is a loose implementation of the model of resource search discussed in

Simon HA 1956 Rational choice and the structure of the environment. Psychological Review, 63, 129-138.

The model demonstrates the importance of relative direct movement for search efficiency, and the importance of vision, in an environment where resources are relatively rare.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.

4.2 demonstration of the correlation length effect in random walks

This model demonstrates how a correlated random walk, when consecutive steps are aggregated, reverts to a simple random walk without correlation but with a longer mean step length. This effect means that correlated random walks are ultimately diffusive (not super-diffusive) like simple random walks.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.

4.1 random walks

This model implements a number of variations on the random walk including the lattice-based walk, the simple random walk, walks with different distributions of step lengths, and correlated (direction) random walks.

Two variants are shown in the videos to the right: a simple random walk, and a directionally correlated random walk.

Click on the image to download and save the model NetLogo file. You will need to install NetLogo to run this file.