雅思阅读 44: Why Losses Outweigh Gains（为何失去比得到更沉重）

改编由 Kahneman & Tversky / Behavioural economics literature（2024-2025）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://landing-dev.argumentree.com/blog/prospect-theory-decisions/

Reading Passage

A. Standard economic theory assumes that human beings are rational calculators. Given a choice between certain gains and probabilistic ones, the textbook picture says we should multiply each outcome by its probability and select the option with the highest expected value. This assumption, formalised in the middle of the twentieth century by economists such as Paul Samuelson and Milton Friedman, worked well for describing markets in the aggregate — prices did adjust to information, arbitrage did close — but it failed repeatedly when researchers sat real people in laboratories and asked them to choose. In a famous series of experiments in the late 1970s, Daniel Kahneman and Amos Tversky demonstrated that choices were not governed by final wealth states but by changes from an internal reference point — the price already paid, the status quo, the expectation of what should happen. Their 1979 paper on "prospect theory", published in the journal Econometrica, overturned decades of economic orthodoxy and earned Kahneman a Nobel Prize in 2002. Tversky died in 1996, too early to share it; the Nobel committee does not award prizes posthumously. The pair had met while working at the Hebrew University of Jerusalem, and their collaborations were famously conducted through long telephone conversations rather than formal drafts.

B. The central finding was that losses hurt more than equivalent gains feel good. Losing a hundred dollars is not simply the mirror image of winning a hundred dollars; it is roughly twice as painful. The mathematical function describing this asymmetry, known as the loss-aversion coefficient, was estimated at about 2.25 — meaning the pain of a loss weighs more than twice as heavily as the pleasure of a gain of the same size. This single parameter explains a surprising number of otherwise puzzling behaviours. Investors hold losing shares for too long because selling would turn a paper loss into a realised one. Sellers demand more for an object they already own than buyers will pay for the identical object — the so-called endowment effect, demonstrated in experiments where half the subjects are given a mug and then asked to price it. Consumers respond more strongly to a penalty framed as a "loss" than to an identical amount framed as a "discount", and homeowners delay selling their houses in a falling market rather than accept a price below what they originally paid. The asymmetry is so consistent that it is now treated as a universal feature of human judgement, rather than an artefact of the laboratory setting.

C. A second, equally counterintuitive finding was how people handle probabilities. Rather than weighting each outcome by its true likelihood, people apply a distorted "decision weight": they over-weight very small probabilities, which is why lottery tickets and insurance policies both sell, and they under-weight probabilities that are merely high. A ninety-five per cent chance of winning a hundred dollars is treated as if it were worth less than ninety-five dollars — because the small chance of disappointment itself is painful. Conversely, when faced with a ninety-five per cent chance of losing a hundred dollars, people become willing gamblers, preferring a risky gamble that might wipe out the loss to a certain smaller loss. The same person is risk-averse in the domain of gains and risk-seeking in the domain of losses, depending only on how the problem is framed. Tversky and Kahneman called this the "reflection effect", and it meant that no coherent preference between two options could be inferred until the experimenter knew which way the options were described. The effect is robust enough that advertisers and political campaigns now routinely exploit it, framing policies as either losses or gains depending on which they want voters to prefer.

D. These effects have proved remarkably robust across cultures, age groups and decision contexts. They appear in laboratory gambles with small sums, in financial markets over decades, in medical decisions between surgery and radiation, and in environmental choices about whether to pay a carbon tax. Yet recent work has also exposed limits. Not every person shows the same degree of loss aversion — some individuals appear almost neutral — and some experiments with very large stakes find weaker effects, suggesting that when money matters enough, deliberation can override intuition. Neuroscientists, using functional magnetic resonance imaging, have traced loss aversion to activity in the amygdala and insula — regions associated with threat and disgust — while effortful "deliberative" thinking, housed in the prefrontal cortex, can partly override it. The two-system model that emerged from this work, popularised in Kahneman's later book Thinking, Fast and Slow, distinguishes an automatic, emotional "System 1" from a slow, calculating "System 2". Critics have argued that the two systems are more overlapping than the model suggests, but the broad distinction remains influential in psychology and economics.

E. The practical stakes are large. Public policy has begun to borrow directly from prospect theory. Pension schemes automatically enrol workers, with the option to opt out, because people are more sensitive to the loss of money taken from a pay packet than to the gain of a pension contribution. Energy companies send householders reports comparing their consumption to neighbours', because a "you are using more than your peers" letter works better than an exhortation to save. Tax authorities send letters emphasising that non-compliance is already the exception, not the rule. At the same time, critics warn that the same tools can be used to manipulate: a default option chosen by a regulator can quietly nudge citizens toward choices they would never have made freely, and the European Commission has proposed rules requiring that defaults be transparent and reversible. Prospect theory, in other words, describes not a flaw in human rationality to be corrected, but a feature of how the mind actually works — one that governments, firms and doctors ignore at their peril. Whether that feature is ultimately wise is another question, but it is undeniable.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. The asymmetry between losses and gains ii. How the two-system model was first disproved iii. Why people distort probabilities iv. The limits of the theory and its neural basis v. How prospect theory is now applied in policy vi. A brief history of stock market crashes vii. Why insurance companies went bankrupt

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. According to prospect theory, how do people evaluate outcomes? A. By their final wealth alone. B. By changes relative to a reference point. C. By the advice of financial experts. D. By ignoring probabilities entirely.

6. What is the approximate loss-aversion coefficient? A. About 0.5. B. About 1.0. C. About 2.25. D. About 10.

7. Why do people buy both lottery tickets and insurance? A. They over-weight very small probabilities. B. They under-weight all probabilities. C. They are indifferent to risk. D. They calculate expected value perfectly.

8. How do policy-makers use prospect theory? A. They ban automatic enrolment in pensions. B. They use default options and social comparisons to nudge behaviour. C. They forbid energy reports. D. They require everyone to gamble.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. Kahneman and Tversky published prospect theory in 1979.
10. Tversky shared the Nobel Prize with Kahneman in 2002.
11. People tend to become risk-seeking when facing probable losses.
12. Loss aversion has been shown to be identical in every human population studied.
13. Kahneman and Tversky were both born in the United States.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

The (14) __________ effect describes why sellers ask more for an object they already own than buyers will pay for the same one, and arises because (15) __________ loom larger than equivalent gains.

答案与解析

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