Chemical reactions do not generally display dynamic patterns or spatial order. The Belousov-Zhabotinsky reaction, discovered in 1951, may be the first completely understandable laboratory example of pattern formation in a chemical system that involves nothing more than chemical reaction and molecular diffusion. That same year, in 1951, Alan Turing investigated the theoretical possibilities of pattern formation by reaction/diffusion as "The chemical basis of Morphogenesis." The B/Z reaction is an example of a chemical system that shows spatial, periodic and wave properties that suggests that morphogenetic self-organization might follow similar pathways in both inorganic and organic systems. (cf. Slime Mold)
from Arthur T. Winfree, When Time Breaks Down, p. 168
feedback
schismogenesis
Gregory Bateson uses this term to describe progressive differentiation between social groups or individuals. For example, if two groups exhibit symmetrical behaviour patterns towards each other that are different from the patterns they exhibit within their respective groups, they can set up a feedback , or "vicious cycle" relation. For example, if boasting is the way they deal with the other group, and if the other group replies to boasting with more boasting, then each group will drive the other into excessive emphasis on the pattern, leading to more extreme rivalry, and ultimately to hostility and the breakdown of the system. (Steps towards an Ecology of Mind, p. 68) An arms race is another symmetrical form of schismogenesis.