Evans – in two minds: dual-process accounts of reasoning
Summary of "In Two Minds: Dual-Process Accounts of Reasoning" (Evans, 2003)
This paper discusses dual-process theories of reasoning, which propose two distinct cognitive
systems: System 1 (intuitive, automatic thinking) and System 2 (deliberate, analytical reasoning).
The study connects these theories to behavioral economics, judgment, and decision-making,
which align with your midterm study guide topics.
1. Dual-Process Theory Overview
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System 1 (Intuitive, Fast Thinking)
o Evolutionarily older, shared with animals.
o Automatic, unconscious, and relies on heuristics.
o Based on associative learning and past experiences.
o Prone to cognitive biases (e.g., belief-bias, matching bias).
System 2 (Analytical, Slow Thinking)
o Unique to humans, evolved more recently.
o Requires working memory and cognitive effort.
o Allows abstract, hypothetical thinking.
o Can override System 1 but is limited in capacity.
2. Evidence for Dual Processes in Reasoning
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Belief-Bias Effect (Box 1)
o People judge arguments based on believability rather than logic.
o Example:
 Valid argument with an unbelievable conclusion → harder to accept.
 Invalid argument with a believable conclusion → often wrongly accepted.
Wason Selection Task (Box 3)
o Logical reasoning problem showing System 1’s heuristic influence.
o Abstract version: Few solve it correctly.
o Real-world version (police checking underage drinkers): Higher success.
Neuropsychological Evidence (Box 2)
o fMRI studies show different brain regions activate for System 1 vs. System 2.
o Logical reasoning (System 2) is associated with the right prefrontal cortex.
o Intuitive, belief-driven reasoning (System 1) activates the ventral medial prefrontal
cortex.
3. Individual Differences in Reasoning Ability
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System 2 requires working memory capacity, which varies between individuals.
Higher cognitive ability (measured by SAT scores) correlates with:
o Better logical reasoning (System 2)
o Better resistance to cognitive biases
Aging reduces System 2 function, leading to more reliance on System 1.
4. Dual-Processes in Judgment and Decision-Making
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Connections to Prospect Theory (aligns with your study guide!)
o People rely on heuristics and biases (System 1) when making decisions.
o Example: Overweighing small probabilities (lotteries, insurances).
Bayesian Reasoning and Base Rate Neglect
o People ignore base rates in statistical problems because System 2 reasoning is
required.
o If base rates are framed as personal experiences, System 1 processes them better.
5. Evolutionary Arguments
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System 2 evolved later, allowing abstract reasoning and future planning.
System 1 consists of modular, domain-specific processes (e.g., recognizing danger).
Evolutionary psychology debates whether System 2 is truly general-purpose or if cognition
is massively modular.
6. Key Takeaways for Your Midterm
1. System 1 vs. System 2: Understand their differences and applications.
2. Cognitive Biases: Belief-bias effect, matching bias, and how System 1 interferes with logical
reasoning.
3. Prospect Theory Connection: Overweighting small probabilities, framing effects.
4. Neuroscientific Evidence: Different brain areas for belief-based vs. logic-based reasoning.
5. Applications in Decision-Making: Heuristics, biases, risk aversion, and rationality.