Sociology and economics study things at highest level. Culture has learned this behaviour and hence this culture has better reproduction. If conditions are met, then you do the action that follows. Theory says we have thousands of these in our head. At every moment the production is waiting for its condition to be applied. If you are full you will not always eat the chocolate if you see it. By changing the parameter or adding another condition is ways in which production system change. Association happens when two parts of the mind are active at the same time, the brain change so that likelihood that they are active together in the future increases. Cognitive science not interested in this level so much. Neuron is living cell that uses chemicals to create messages. For example: ontology of astrology is not precise or real. ". No point in higher level studies because they can be further deduced by lower level studies.