A scientist who does research in economic psychology and who wants to predict the way in which consumers will spend their money must study consumer behavior. He must obtain data both on the resources of consumers and on the motives that tend to encourage or discourage money spending. If an economist were asked which of the three groups borrow most—people with rising incomes, stable incomes or declining incomes—he would probably answer: those with declining incomes. Actually, in the years 1947~1950, the answer was: people with rising incomes. People with declining incomes were next and people with stable incomes borrowed the least. This show us that traditional assumptions about earning and spending are not always reliable. Another traditional assumptions is that if people who have money expect prices to go up, they will hasten to buy. If they expect prices to go down, they will postpone buying. But research surveys have shown that this is not always true. The expectations of price increases may not stimulate buying. The investigations mentioned above were carried out in America . Investigations conducted at the same time in Great Britain , however, yielded results that were more in agreement with traditional assumptions about saving and spending patterns. The condition most favorable to spending appears to be price stability. If prices have been stable and people consider that they are reasonable, they are likely to buy. Thus, it appears that the common business policy of maintaining stable prices is based on a correct understanding of consumer psychology.