EigoPro 1級 読解 — The Calculus of Choice: Inside the Deciding Brain

For centuries, decision-making was the philosopher's preserve, conceived as the deliberation of a rational agent weighing costs against benefits with dispassionate precision. Contemporary neuroscience has dismantled this tidy fiction. Far from issuing from a single seat of reason, every choice we make emerges from a fractious negotiation among competing neural circuits, each vying to impose its valuation on the body's motor apparatus. The brain, it turns out, does not so much decide as adjudicate. Central to this account is the notion of value computation. When confronted with options, the brain does not retrieve fixed worths from some internal ledger; instead, regions such as the ventromedial prefrontal cortex assign provisional values on the fly, integrating expected reward, effort, risk, and the corrosive influence of delay. A reward deferred is a reward discounted, and the steepness of this temporal discounting varies markedly across individuals, predicting everything from dietary lapses to financial improvidence. Crucially, these valuations are not computed in a vacuum: the orbitofrontal cortex continually recalibrates them against context, so that a glass of water commands extravagant value in the desert and scarcely any at the dinner table. Value, in the brain's grammar, is irreducibly relative. Yet computation is only half the story. Dopaminergic neurons, long miscast as the simple couriers of pleasure, in fact encode prediction error—the discrepancy between anticipated and actual outcomes. It is this signal, not reward itself, that tutors the system, nudging future valuations toward accuracy. Herein lies a paradox the older models could not accommodate: the very mechanism that renders us adaptive learners also renders us exquisitely manipulable, for any environment engineered to lavish unpredictable rewards—the slot machine, the social feed—hijacks this circuitry with ruthless efficiency. What philosophy framed as a failure of will, neuroscience reframes as a feature of design operating precisely as evolution intended, merely in a habitat it never anticipated. The deciding brain, then, is neither the sovereign reasoner of Enlightenment portraiture nor a mere bundle of reflexes, but something stranger: a parliament of valuations, perpetually provisional, forever susceptible to the architecture of its surroundings.

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この単元の問題を3問、解説つきで公開しています

1級 · 読解 · 全5問

問 1

Which statement best captures the central argument of the passage?

  • Decision-making arises from the competitive interaction of multiple value-computing neural systems rather than from a single rational faculty.
  • Modern environments such as social media have permanently damaged the brain's capacity to make sound decisions.
  • Neuroscience has confirmed the classical philosophical view that humans deliberate as rational agents weighing costs and benefits.
  • Dopamine functions principally as a chemical reward that motivates the brain to pursue pleasurable outcomes.
Phrase

a parliament of valuations

1級読解主旨把握論旨
⚡ひとことで

意思決定は単一の理性ではなく複数の価値計算回路の競合から生じる。

選択肢の解説Choice Analysis

「Decision-making arises from the competitive interaction of multiple value-computing neural systems rather than from a single rational faculty.」

正解

本文は冒頭で「単一の理性」という古典的見解を tidy fiction として退け、選択は competing neural circuits の fractious negotiation から生じると述べる。結論でも a parliament of valuations と表現し、複数回路の競合が中心論旨であることを明示している。よってこれが本文全体を最も適切に要約する。

  • 「Neuroscience has confirmed the classical philosophical view that humans deliberate as rational agents weighing costs and benefits.」

    = 人は理性的に損得を計ると神経科学が裏付けた ━ 本文はその見解を dismantled this tidy fiction と明言し否定しているため逆。

  • 「Dopamine functions principally as a chemical reward that motivates the brain to pursue pleasurable outcomes.」

    = ドーパミンは快楽を伝え動機づける ━ 本文は long miscast as couriers of pleasure とし prediction error を符号化すると訂正している。

  • 「Modern environments such as social media have permanently damaged the brain's capacity to make sound decisions.」

    = 現代環境が脳の意思決定を恒久に損なった ━ 本文は hijack を語るが permanent damage には言及せず、設計上の特徴と位置づける。

▦Collocation
パターン意味例
weigh costs against benefits損得を秤にかけるRational agents are said to weigh costs against benefits.
emerge from〜から生じるEvery choice emerges from a neural negotiation.
impose X on YXをYに押し付けるEach circuit vies to impose its valuation on the body.
far from doing〜どころかFar from issuing from one seat of reason, choice is distributed.
a negotiation among〜間の交渉A fractious negotiation among competing circuits unfolds.
❝例文

  • The verdict emerged from a long negotiation among the jurors.

    評決は陪審員たちの長い交渉から生じた。

  • Far from being settled, the debate had only just begun.

    議論は決着どころか、まだ始まったばかりだった。

  • They tried to impose their standards on every department.

    彼らは自分たちの基準を全部門に押し付けようとした。

  • The brain adjudicates rather than simply decides.

    脳は単に決めるというより裁定する。

💡Tip · 覚えるコツ

主旨問題では冒頭と末尾のパラフレーズを照合せよ。C2 の論説はしばしば「旧説を却下→新説を提示」の構造を取るので、dismantled / reframes などの転換動詞が論旨の向きを示す。部分的に正しい詳細（ドーパミン等）を主旨と取り違えないこと。

問 2

According to the passage, how does the brain assign value to options?

  • It generates provisional values on the fly by integrating reward, effort, risk, and delay, recalibrated according to context.
  • It computes absolute values that remain stable regardless of circumstances.
  • It retrieves predetermined worths stored in a fixed internal ledger.
  • It relies solely on dopamine signals to determine the pleasure each option will yield.
Phrase

value computation

1級読解詳細価値計算
⚡ひとことで

脳は報酬・努力・リスク・遅延を統合しその都度暫定的に価値を付ける。

選択肢の解説Choice Analysis

「It generates provisional values on the fly by integrating reward, effort, risk, and delay, recalibrated according to context.」

正解

第2段で the brain does not retrieve fixed worths ではなく assign provisional values on the fly、integrating expected reward, effort, risk, and delay と明記される。さらに orbitofrontal cortex が context に応じて recalibrates し、Value is irreducibly relative と結ぶ。よって暫定的かつ文脈依存が正解。

  • 「It retrieves predetermined worths stored in a fixed internal ledger.」

    = あらかじめ保存された価値を引き出す ━ 本文は does not retrieve fixed worths from some internal ledger と明示的に否定。

  • 「It relies solely on dopamine signals to determine, in advance, the quantity of pleasure that each available option will eventually yield.」

    = 価値付けはドーパミン信号だけに依る ━ ドーパミンは prediction error であり価値計算は vmPFC・OFC が担うと区別されている。

  • 「It computes absolute values that remain stable regardless of circumstances.」

    = 文脈に依らず安定した価値を計算 ━ Value is irreducibly relative・砂漠と食卓の水の例と正反対。

▦Collocation
パターン意味例
on the flyその都度・即座にThe cortex assigns values on the fly.
integrate A, B and CA・B・Cを統合するIt integrates reward, effort and risk.
recalibrate X against YXをYに照らし再調整するThe OFC recalibrates value against context.
command value価値を持つ・集めるWater commands extravagant value in the desert.
irreducibly relative本質的に相対的Value is irreducibly relative in the brain.
❝例文

  • Prices are set on the fly according to demand.

    価格は需要に応じてその都度設定される。

  • The model integrates cost, time and risk into one score.

    そのモデルはコスト・時間・リスクを一つのスコアに統合する。

  • We had to recalibrate our estimate against new data.

    新しいデータに照らし見積もりを再調整せざるを得なかった。

  • In a drought, clean water commands enormous value.

    干ばつでは清潔な水が莫大な価値を持つ。

💡Tip · 覚えるコツ

詳細問題では本文の動詞（retrieve ではなく assign）の否定・肯定に注意。「not X but Y」構造は誤答に X をそのまま使う罠を仕掛けやすい。fixed / absolute / stable といった語は本文の provisional / relative と正反対なので警戒。

問 3

What does the passage identify as the actual function of dopaminergic neurons?

  • They deliver pleasure directly in proportion to the size of a reward received.
  • They suppress impulsive behaviour by counteracting the influence of delay.
  • They assign provisional values to options before a choice is made.
  • They encode prediction error—the gap between anticipated and actual outcomes—which guides future valuations toward accuracy.
Phrase

prediction error

1級読解詳細ドーパミンの機能
⚡ひとことで

ドーパミンニューロンは快楽ではなく予測誤差を符号化し学習を導く。

選択肢の解説Choice Analysis

「They encode prediction error—the gap between anticipated and actual outcomes—which guides future valuations toward accuracy.」

正解

第3段で dopaminergic neurons は long miscast as couriers of pleasure だが実際は encode prediction error—the discrepancy between anticipated and actual outcomes と明記される。さらに it is this signal, not reward itself, that tutors the system とあり、将来の価値を精度へ導くと述べられるためこれが正解。

  • 「They deliver pleasure directly and immediately, in strict proportion to the magnitude of the reward that is actually received.」

    = 報酬の大きさに比例し快楽を与える ━ long miscast as couriers of pleasure / not reward itself と明示的に否定される旧説。

  • 「They assign provisional values to options before a choice is made.」

    = 選択肢に暫定価値を割り振る ━ それは vmPFC/OFC の役割でありドーパミンの機能と混同している。

  • 「They suppress impulsive behaviour by counteracting the influence of delay.」

    = 遅延の影響を打ち消し衝動を抑える ━ 本文にそのような記述はなくもっともらしいが無関係。

▦Collocation
パターン意味例
miscast as〜と誤って位置づけられたDopamine was long miscast as a pleasure courier.
encode XXを符号化するThe neurons encode prediction error.
the discrepancy between A and BAとBの乖離the discrepancy between expected and actual reward
nudge X toward YXをYへ促すThe signal nudges valuations toward accuracy.
tutor the system仕組みを調教するIt is this signal that tutors the system.
❝例文

  • The thermostat responds to the discrepancy between target and actual temperature.

    サーモスタットは目標と実温の乖離に反応する。

  • He was miscast as the villain when he is really the hero.

    彼は実は主役なのに悪役と誤って見なされていた。

  • Small rewards nudged the students toward better habits.

    ささやかな報酬が生徒をより良い習慣へ促した。

  • Feedback, not praise, is what truly tutors a learner.

    学習者を本当に調教するのは賛辞ではなくフィードバックだ。

💡Tip · 覚えるコツ

C2 では「long miscast as…, in fact…」のような「誤解→実態」の言い回しが頻出。誤解の側（pleasure courier）をそのまま正解として提示する誤答に注意。not X itself, but Y の構造で Y を拾えば良い。

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