Final answer:
Decreased consumption of rice in China after a price decrease showcases the income and substitution effects, which are exceptions to the normal law of demand.
Step-by-step explanation:
The empirical evidence found by two economists that shows a decrease in the consumption of rice in Hunan Province, China, after a decrease in its price is a real-world example of the income effect and the substitution effect at play. Normally, the law of demand states that a lower price will lead to a higher quantity demanded. However, this situation shows that there are exceptions to this rule, mainly explained by the income and substitution effects. The income effect occurs when a change in the price of a good alters a consumer's buying power. For example, if rice becomes cheaper, locals may feel their purchasing power has increased and might decide to purchase higher-quality or more varied foods, reducing their intake of rice despite its lower price.
The substitution effect happens when consumers opt for a substitute when a good becomes either more expensive or cheaper - they may, for instance, decide to buy a more expensive alternative to rice that is now relatively more affordable due to an increase in their real income or different consumption preferences.