The applicability of this paradigm to consumer behavior in supermarkets is readily evident. Shoppers are influenced by many taste factors that have their origins in culture, climate, biology, and so on. If these factors are held constant, however (by abstracting from them or assuming that they have not changed), we can see that consumer choices are determined by income and by the prices of the commodities themselves. A rise in income (prices and other things remaining the same) will sharply increase the demand for filet mignon and other luxuries; a decline in income will have the reverse effect. How large the change will be for each commodity depends upon its income elasticity of demand-the percent change in the quantity demanded divided by the percent change in income.