 module 9, Curie of Consumer Behavior. Economics categorize individuals under the subheading of consumers and producers. And the major concern in economics is how to produce and consume in a society. For example, when we make discussion about the consumer, these are the people in a society that consumes and similarly producers are the individuals in a society who produce in a society. In fact, an individual act as consumer and producer simultaneously. So, we are not in a very good position to make a clarification whether an individual is a consumer or producer. For example, if we make discussion with reference to a farmer, farmer act as a producer and consumer simultaneously. For example, as a producer, farmer produces weight to earn his livelihood and at the other end as a consumer, he uses that weight to keep himself alive. But whenever we study the behavior in social sciences, the conditions are not under the control of the individual. And some same thing when we analyze under the natural sciences, then conditions are very much controlled under the individual. So, to make a clarification whether the consumer behavior will be different than the working of the things under the controlled environment, one should have clarification about the natural sciences and social sciences. In natural sciences, actions can be studied in the controlled conditionalities. For example, if we make discussion about the photosynthesis, photosynthesis is a process where light converts into plant growth. So, here light is a stimulus that converts into plant growth. Similarly, if we make discussion with reference to chemistry and other natural science, where we combine different chemicals, different components to produce something other. For example, if sodium and chloride are added and the controlled conditionalities, it results in sodium chloride. So, in natural sciences, we can study the phenomena under very controlled conditions. While in social sciences, actions cannot be studied under controlled environment. Economic behavior of the consumers are usually not be studied in such a controlled conditionalities. For example, if we make discussion about the behavior of a consumer when there is a fall in price of a commodity, it results in increase in quantity demand for that particular commodity. Here price acts as a stimulus while demand acts as a response. If we make discussion with reference to demand for milk, if price of milk increases, it results in decrease in demand for milk. But, decreasing demand for milk will be different for different individuals. Even if we keep all other things in similar setup. For example, if we make discussion with reference to twins who are more or less very similar socioeconomic conditionalities, but their demand for milk will be different for changing same price level. So, economic process cannot be studied in controlled environment and to study economic processes or to study the consumer behavior, we usually have to develop certain assumptions. To study the economic behavior of the consumer, we have to set up certain assumptions and on the basis of those assumptions, we have to formulate a model. To understand the difference in the consumer behavior, one should require about the understanding of the consumer behavior and to understand consumer behavior, one have to make certain assumptions to analyze the behavior of the consumer and those assumptions and we usually assume whenever we study the behavior of the consumer, the consumer is rational and his objective is only to maximize his satisfaction. So, being rational even within similar conditionalities, economic conditionalities, behavior of the consumer is different and in fact, theory of the consumer behavior is about the allocation of limited income by a consumer among different goods and services to maximize his satisfaction. To understand consumer behavior in fact, one should have proper understanding about preferences, budget constraint and consumers choice.