Day 084 — Reading: The Psychology of Decision-Making

2026-07-07 Phase 2 — Band 6.0 目標 Reading（火曜） T/F/NG + Matching Headings + Short Answer | 13問 | 20分

背景知識

Reading Day — 火曜

今日は Academic Reading — Psychology & Economics（意思決定の心理学） の練習です。テーマは Behavioural Economics（行動経済学） — IELTS 本番でも頻出するアカデミック分野で、科学・社会・経済が交差する読み応えのあるパッセージです。

設問形式今日の出題数攻略ポイント
True / False / Not Given6問（Q1〜6）「矛盾」と「情報なし」を区別する
Matching Headings4問（Q7〜10）各段落の main idea をつかむ
Short Answer3問（Q11〜13）NO MORE THAN THREE WORDS でパッセージから抜き出す
今日のテーマ: 行動経済学（Behavioural Economics）
cognitive bias（認知バイアス）・heuristic（経験則）・loss aversion（損失回避）・nudge policy（ナッジ政策） などの語彙が登場します。ソフトウェアエンジニアとしてAI/UXにも繋がる知識なので、背景理解を活かしましょう。

T/F/NG 採点基準

判定条件判定方法
TRUE本文の内容と一致する本文に同じ意味の記述がある
FALSE本文の内容と矛盾する本文に逆の意味の記述が明確にある
NOT GIVEN本文に情報がない本文から判断できない（常識・推論は不可）
最頻出ミス: NOT GIVEN と FALSE の混同
NOT GIVEN = 「本文に書かれていない」。FALSE = 「本文と正反対のことが明確に書かれている」。
自分で推論・常識で判断した結果は必ず NOT GIVEN。

パッセージ

⏰ 目安: パッセージ読解 8分 / 設問 12分
READING PASSAGE

THE PSYCHOLOGY OF DECISION-MAKING

A For centuries, economists assumed that human beings were fundamentally rational actors — individuals who carefully weigh available information, calculate potential outcomes, and consistently choose the option that maximises their benefit. This model, known as Homo economicus, formed the bedrock of classical economic theory. However, from the mid-twentieth century onwards, a growing body of research began to challenge this assumption, revealing that human decision-making is far more complex, inconsistent, and influenced by psychological factors than previously believed.
B Among the pioneers of this challenge were psychologists Daniel Kahneman and Amos Tversky, whose collaborative research in the 1970s laid the foundations of what would later become behavioural economics. Their landmark work introduced the concept of cognitive biases — systematic errors in thinking that affect the judgements and decisions people make. Unlike random errors, cognitive biases follow predictable patterns, meaning that under certain conditions, most people will make the same type of mistake. This insight had profound implications not only for economics but also for fields ranging from medicine and law to public policy.
C One of the most well-known biases identified by Kahneman and Tversky is the availability heuristic. This refers to the tendency for people to judge the likelihood of an event based on how easily relevant examples come to mind. For instance, after seeing extensive media coverage of aeroplane accidents, many individuals overestimate the risk of flying while simultaneously underestimating the far greater statistical danger posed by car travel. The information that is most mentally accessible — rather than the most statistically accurate — disproportionately shapes our perception of risk.
D Closely related is the concept of anchoring, which describes the human tendency to rely heavily on the first piece of information encountered when making decisions. In a seminal experiment, Kahneman and Tversky asked participants to estimate the percentage of African countries in the United Nations after first watching a wheel of fortune spin to a random number. Remarkably, participants who saw a high number (such as 65) provided significantly higher estimates than those who saw a low number (such as 10), despite the wheel result being entirely arbitrary. The initial figure, even when irrelevant, had anchored their subsequent judgement.
E Another influential concept from behavioural economics is loss aversion, which was central to Kahneman and Tversky’s Prospect Theory, introduced in 1979. This theory argues that humans experience the psychological pain of losing something as approximately twice as powerful as the pleasure of gaining an equivalent amount. In practical terms, this means that a person would typically demand to win around £200 to justify accepting a 50% chance of losing £100. Loss aversion helps explain a wide range of seemingly irrational behaviours, from investors holding on to poorly performing stocks to avoid realising a loss, to consumers refusing to switch utility providers despite potential savings.
F The implications of behavioural economics extend well beyond academic research. Governments and organisations around the world have applied its insights through the design of nudge policies — subtle changes to the environment or choice architecture that steer people towards more beneficial decisions without restricting freedom. One notable example is the shift from opt-in to opt-out pension enrolment. Studies conducted in the United Kingdom and the United States showed that when employees were automatically enrolled in workplace pension schemes and required to actively opt out if they did not wish to participate, enrolment rates increased dramatically — in some cases from below 50% to over 90%. The change did not compel anyone to save; it simply altered the default option.
G Critics of behavioural economics, however, argue that nudge policies can be manipulative, as they exploit psychological weaknesses rather than encouraging genuine informed choice. Furthermore, some researchers contend that the field overestimates the universality of cognitive biases. Cross-cultural studies have suggested that the strength and prevalence of certain biases vary significantly between societies, raising questions about whether findings from Western laboratory settings can be reliably applied globally. Proponents, meanwhile, counter that even an imperfect tool for improving public welfare is more valuable than theoretical models that bear little resemblance to actual human behaviour.

設問

Questions 1–6: True / False / Not Given
Do the following statements agree with the information given in the reading passage?

Write TRUE if the statement agrees with the information
Write FALSE if the statement contradicts the information
Write NOT GIVEN if there is no information on this topic
1
Classical economic theory assumed that people always make logical and self-interested decisions.
2
Cognitive biases produce random, unpredictable errors in human judgement.
3
Kahneman and Tversky began their influential collaboration in the 1980s.
4
The availability heuristic causes people to overestimate risks that receive heavy media attention.
5
In the anchoring experiment, participants were told to ignore the wheel of fortune result.
6
Prospect Theory suggests that people feel more strongly about losing money than gaining the same amount.
Questions 7–10: Matching Headings
The passage has seven paragraphs, A–G. Choose the correct heading for each paragraph from the list of headings below.
  • i. A critique of nudge-based approaches
  • ii. The origin of traditional economic assumptions
  • iii. When irrelevant information shapes our estimates
  • iv. The asymmetry between gains and losses
  • v. The birth of behavioural economics
  • vi. Applying psychological insights to public policy
  • vii. How media exposure distorts our judgement of risk
7
Paragraph B
8
Paragraph D
9
Paragraph E
10
Paragraph F
Questions 11–13: Short Answer
Answer the following questions using NO MORE THAN THREE WORDS from the passage.
11
What term describes the model of a perfectly rational economic decision-maker?
12
In the opt-out pension experiment, what happened to enrolment rates after the change in policy?
13
According to critics, what do cross-cultural studies suggest varies significantly between societies?

有用な語彙・表現

語彙・表現日本語訳使用例
bedrock of〜の基盤・礎the bedrock of classical economic theory
cognitive bias認知バイアスcognitive biases follow predictable patterns
heuristic経験則・ヒューリスティックthe availability heuristic
anchoringアンカリング（初期値への依存）the initial figure had anchored their judgement
loss aversion損失回避loss aversion helps explain irrational behaviours
nudge policyナッジ政策governments have applied nudge policies
opt-in / opt-out能動的参加 / 能動的離脱the shift from opt-in to opt-out pension enrolment
choice architecture選択設計subtle changes to the choice architecture
seminal画期的な・先駆的なa seminal experiment
arbitrary恣意的な・無根拠なthe wheel result being entirely arbitrary

ヒント

T/F/NG の最大の罠は「常識で答える」こと。パッセージに根拠があるかどうかだけを判断する。

  • Q2: "random" というキーワードに注目。パッセージには "predictable" という語がある。
  • Q3: 年代（decade）が問われている。パッセージには "1970s" という記述がある。
  • Q5: 実験の手順の詳細（「無視するよう指示された」かどうか）はパッセージに書かれているか確認。

各段落の 最初の文と最後の文 を重点的に読む。段落の main idea を1〜2語で言い換えてから headings リストと照合する。

  • Q7（段落B）: Kahneman と Tversky の研究と behavioural economics の誕生について説明している。
  • Q8（段落D）: anchoring の実験（無関係な数字が推定に影響する）について説明している。
  • Q9（段落E）: loss aversion と Prospect Theory（得と損の非対称性）について説明している。
  • Q10（段落F）: nudge policies と年金制度への応用（実社会への適用）について説明している。

Short Answer のコツ: パッセージの中の "known as"・"called"・"termed" などの定義表現の近くに答えがあることが多い。

  • Q11: 段落 A に "This model, known as ___" という定義表現がある。
  • Q12: 段落 F の opt-out pension の説明の中に "enrolment rates ___" という結果が書かれている。
  • Q13: 段落 G の "the ___ of certain biases vary significantly" がそのまま答えになる。

解答・解説

問解答パッセージの根拠
1 TRUE Paragraph A: "carefully weigh available information…consistently choose the option that maximises their benefit"
"benefit を最大化する選択を一貫して行う" = 合理的行動者の仮定と一致
2 FALSE Paragraph B: "Unlike random errors, cognitive biases follow predictable patterns"
設問の "random, unpredictable" は本文の "predictable" と正反対
3 FALSE Paragraph B: "collaborative research in the 1970s"
設問の "1980s" は本文の "1970s" と矛盾
4 TRUE Paragraph C: "after seeing extensive media coverage of aeroplane accidents, many individuals overestimate the risk of flying"
メディア報道量 → リスク過大評価 という因果関係と一致
5 NOT GIVEN Paragraph D: 実験の手順については記述あるが、「無視するよう指示された」という内容はない
パッセージに「指示の詳細」は書かれていない → NOT GIVEN
6 TRUE Paragraph E: "losing something as approximately twice as powerful as the pleasure of gaining an equivalent amount"
損失の痛み = 利益の喜びの約2倍 → 損失に対してより強く感じる
問段落解答理由
7 B v. The birth of behavioural economics Kahneman と Tversky の研究が behavioural economics を生み出したことを説明
8 D iii. When irrelevant information shapes our estimates wheel of fortune という無関係な数字が推定値に影響した anchoring の実験を説明
9 E iv. The asymmetry between gains and losses Prospect Theory: 損失の痛み ≒ 利益の喜びの2倍という非対称性を説明
10 F vi. Applying psychological insights to public policy nudge policies・opt-out 年金制度という実社会への政策応用を説明
使用しなかった headings:
i（批判は段落G）/ ii（伝統的仮定は段落A）/ vii（メディアとリスクは段落C）
これらは段落A・C・Gに対応するが、今回の設問には含まれていない。
問解答根拠（パッセージ）
11 Homo economicus Paragraph A: "This model, known as Homo economicus" — 「完全合理的な経済人」モデルの名称
12 increased dramatically Paragraph F: "enrolment rates increased dramatically" — そのまま抜き出し（2語）
13 the strength and prevalence Paragraph G: "the strength and prevalence of certain biases vary significantly" — 3語以内で抜き出し
Short Answer のポイント: Q13 は "the strength and prevalence" (3語) または "strength and prevalence" (2語) どちらも正答。"of certain biases" まで含めると4語になり制限オーバーなので注意。

よくある日本人のミス

ミス原因正しいアプローチ
Q2 を TRUE にしてしまう 「バイアスは予測可能」という本文の記述を見落とす "Unlike random errors, cognitive biases follow predictable patterns" → FALSE
Q5 を FALSE にしてしまう 「どこかに書いてあるはず」と思い込む パッセージに「指示の有無」は明記なし → NOT GIVEN
Matching Headings で段落 D に "vii" を選ぶ D に wheel（車輪）が出てくるため "media" と混同 段落 D は「無関係な数字が判断に影響する」= iii. When irrelevant information...
Q13 で "the strength and prevalence of certain biases" と書く NO MORE THAN THREE WORDS の制限を忘れる "the strength and prevalence" (3語) で止める
スキャニングせず全文精読する 時間管理の意識が低い 設問のキーワードをチェック後、パッセージをスキャン。20分で13問は約1.5分/問

次のステップ

発展: 段落 G の批判的視点（nudge policies are manipulative）を踏まえて「行動経済学のナッジ政策に賛成か反対か」でWriting Task 2 の Outline を書いてみる（"I believe nudge policies are justifiable because…"）
次回予告（水曜）: Writing Task 1 — Line Graph（折れ線グラフ: スマートフォン普及率の推移）

自己評価

問題を解いた後に記入してください。データはブラウザのローカルストレージに保存されます。

気づき・メモ（間違えた問題・理由・次回への課題）: