Behavioral Economics

Behavioral Economics in Microeconomics

Behavioral economics is an emerging interdisciplinary branch of microeconomics that integrates psychology. It breaks through the limitations of the homo economicus assumption in traditional microeconomics, incorporates human psychological factors, cognitive biases, and social preferences into the framework of economic decision-making analysis, and studies how people make economic choices in reality and the impact of these choices on market operation and resource allocation.

Traditional microeconomics assumes that decision-makers are completely rational, self-interested, and utility-maximizing "economic men", while behavioral economics argues that human decisions are significantly influenced by irrational factors such as intuition, emotion, and bias, which is more in line with real economic behaviors.

I. Core Theoretical Foundations of Behavioral Economics

1. Challenging the Traditional Homo Economicus Assumption

Behavioral economics revises the three core assumptions of traditional microeconomics:

  • Bounded Rationality: Humans are not omniscient and omnipotent; they have limited ability to process information. Instead of making decisions through rigorous cost-benefit calculations, people often rely on intuition and heuristic rules.
  • Bounded Self-interest: Humans do not purely pursue their own interests, but also pay attention to social preferences such as fairness, reciprocity, and altruism. For example, people are willing to donate to public welfare or feel dissatisfied with the unfair treatment of others.
  • Bounded Willpower: People find it difficult to fully control their short-term impulses and often engage in "knowingly doing wrong" behaviors. For instance, they clearly plan to save money but cannot resist the urge of excessive consumption; they know smoking is harmful to health but struggle to quit.

2. Prospect Theory

Prospect theory is the core theory of behavioral economics, proposed by Daniel Kahneman and Amos Tversky. It explains the decision-making rules of people under uncertainty and subverts the traditional expected utility theory. Its core viewpoints include:

  • Value Function: People's perception of gains and losses is not linear, but based on a reference point. When facing gains, people are risk-averse (e.g., choosing a certain 100 yuan rather than a 50% chance of getting 200 yuan); when facing losses, people are risk-seeking (e.g., choosing a 50% chance of losing 200 yuan rather than a certain loss of 100 yuan).
  • Loss Aversion: The pain caused by losses is far greater than the pleasure brought by equivalent gains (studies show that the pain of loss is about 2.5 times the pleasure of gain). For example, the sadness of losing 100 yuan is stronger than the joy of finding 100 yuan.
  • Probability Weighting Function: People overestimate the probability of small-probability events (such as overvaluing the possibility of winning the lottery) and underestimate the probability of high-probability events (such as ignoring the safety risks of daily commuting).

II. Key Cognitive Biases and Effects in Behavioral Economics

People exhibit a series of systematic cognitive biases in economic decision-making, which directly affect decision outcomes, mainly including:

  1. Anchoring Effect
    When making judgments, people over-rely on the first piece of information obtained (the "anchor"), even if this anchor is irrelevant to the decision itself. For example, when pricing products, merchants first mark a high "original price" and then offer a discounted price. Consumers will take the original price as the anchor and think the discounted price is a good deal.

  2. Availability Heuristic
    People tend to judge the probability of an event based on the information that is easily accessible in memory. For example, frequent exposure to news about plane crashes will make people overestimate the accident rate of airplanes and underestimate that of cars.

  3. Representativeness Heuristic
    People judge the probability of a thing based on its similarity to a certain "typical prototype", ignoring the base rate. For example, seeing a person dressed formally and wearing glasses, people will think he is a scholar rather than an ordinary office worker, but they ignore the fact that the number of ordinary office workers is much larger than that of scholars.

  4. Framing Effect
    Different expressions of the same problem will affect people's decisions. For example, if a doctor tells a patient that "the survival rate of the operation is 90%", the patient is more willing to accept the operation; if the doctor says "the mortality rate of the operation is 10%", the patient will be more hesitant.

  5. Herd Effect
    People tend to make decisions by following the choices of the majority, ignoring their own judgments. For example, when shopping, people prefer to choose products with high sales volume; when investing, they follow the trend to buy popular stocks.

III. Applications of Behavioral Economics in Microeconomic Fields

1. Consumer Behavior Analysis

Behavioral economics explains many consumption phenomena that cannot be explained by traditional theories:

  • Why do consumers buy non-essential goods with the "buy one get one free" promotion? (Anchoring effect + loss aversion)
  • Why can "free trial" greatly improve conversion rates? (Loss aversion: giving up after trial will generate a sense of "loss")
  • Why do consumers prefer installment payments even if the total cost is higher? (Bounded rationality: ignoring interest costs)

2. Labor and Savings Decisions

  • Savings Behavior: Design "automatic pension deposit" plans using loss aversion—automatically transferring a portion of wages into a pension account. People will regard this part of the money as "lost" income, thereby reducing consumption impulses and increasing savings rates.
  • Labor Supply: Traditional theory holds that wage increases will increase labor supply, but behavioral economics finds that when wages exceed a certain level, people will pay more attention to leisure, and the labor supply curve bends backward, which is related to "bounded self-interest" and "preference diversity".

3. Financial Market and Investment Decisions

Behavioral economics reveals irrational trading behaviors in financial markets:

  • Why do investors chase rising prices and sell at falling prices? (Herd effect + availability heuristic)
  • Why are investors overconfident and frequently trade, leading to losses? (Overconfidence bias)
  • Why do stock prices deviate from their intrinsic value? (Investors' emotional fluctuations and cognitive biases will drive irrational price fluctuations)

4. Policy Formulation (Nudge Theory)

Behavioral economics proposes the "Nudge Theory", advocating that the government does not need mandatory intervention, but only guides people to make more rational choices by adjusting the decision-making environment:

  • Placing healthy food in prominent positions in supermarkets to nudge consumers to choose a healthy diet;
  • Setting "organ donation" as the default option (active opt-out is required for non-donation), which significantly increases the donation rate;
  • Clearly marking the annualized interest rate of credit cards to help consumers realize borrowing costs.

IV. The Relationship Between Behavioral Economics and Traditional Microeconomics

Behavioral economics does not completely negate traditional microeconomics, but supplements and improves it:

  • The "homo economicus assumption" of traditional microeconomics is an ideal model for simplified analysis, applicable to scenarios with sufficient market competition and complete information;
  • Behavioral economics is more in line with reality and explains "abnormal economic phenomena" that cannot be covered by the homo economicus assumption.

The combination of the two can more comprehensively analyze the decision-making behaviors of economic subjects and the laws of market operation.