The Reasoning Test Psychologists Still Can't Explain

The Rest Is Science

7 chapters6 takeaways12 key terms5 questions

Overview

This video explores the Wason selection task, a famous reasoning puzzle that most people fail, and delves into the psychology behind why it's so difficult. It highlights how abstract problems are harder than concrete, social ones, suggesting our reasoning evolved for social interaction rather than pure logic. The discussion touches on concepts like modus tollens, confirmation bias, and the social nature of human decision-making, using examples from everyday life and scientific inquiry to illustrate these points.

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Chapters

The Wason selection task, devised in 1966, is a single-question reasoning test that a vast majority of people fail.
It is considered a cornerstone in the study of human reasoning, with extensive research dedicated to understanding its difficulty.
In its original form, only about 10% of people solved it correctly, with later replications showing success rates closer to 4%.
Despite its difficulty in abstract forms, variations of the task can be made easily solvable by changing the context.

Understanding the Wason selection task is crucial because it reveals fundamental aspects of human reasoning and cognitive biases, showing how context dramatically affects our ability to solve problems.

The abstract version presents four cards (A, G, 7, 8) and the rule: 'If there is an A on one side, there is a 7 on the other.' Participants must choose which cards to flip to verify the rule.

When the Wason task is presented with abstract symbols (letters and numbers), most people struggle to identify the correct cards to check.
However, when the same logical structure is applied to a social scenario, like enforcing a drinking age rule in a bar, people intuitively know which cards to check.
The 'bar' version involves cards showing age (12, 35) and drinks (soda, beer) with the rule: 'If you are drinking alcohol, you must be over the drinking age.'
This stark difference suggests that human reasoning is more adept at handling social rules and obligations than abstract logical propositions.

This contrast demonstrates that our cognitive abilities are not uniformly applied; they are highly sensitive to the framing and context of the problem, particularly favoring social relevance.

In the bar scenario, people instinctively know to check the 12-year-old (to see if they are drinking alcohol) and the beer drinker (to see if they are underage), mirroring the logical requirements of the abstract version but with much higher success rates.

The Wason task tests understanding of conditional statements ('If P, then Q').
Modus Ponens is a valid inference where affirming the antecedent (P is true) allows you to conclude the consequent (Q is true).
Modus Tollens is another valid inference where denying the consequent (Q is false) allows you to conclude the antecedent is false (P is false).
Common errors include denying the antecedent (P is false, therefore Q is false - invalid) and affirming the consequent (Q is true, therefore P is true - invalid).

Understanding these logical forms is key to deconstructing the Wason task and recognizing why certain choices are logically sound while others are fallacious.

For the rule 'If you are drinking alcohol (P), you must be over 21 (Q)', Modus Ponens would be seeing someone drinking alcohol and concluding they are over 21. Modus Tollens would be seeing someone who is not over 21 and concluding they cannot be drinking alcohol.

Researchers propose that human reasoning evolved primarily for social interaction, focusing on detecting cheating and enforcing social contracts.
Deontic rules involve obligations or permissions ('may'), while descriptive rules describe factual states ('can').
People are much better at reasoning about deontic rules (like the drinking age) because they are inherently social and involve potential violations.
Abstract, descriptive rules (like 'If A, then 7') lack this social enforcement mechanism, making them harder to process.

This theory explains why social contexts make reasoning tasks easier, suggesting our brains are 'pre-wired' for social compliance and detection rather than abstract logical truth-finding.

The rule 'If you are drinking alcohol, you must be over the drinking age' is a deontic rule (an obligation), making it easier to process than the descriptive rule 'If there is an A, there is a 7'.

Humans exhibit a strong bias towards seeking confirming evidence rather than falsifying evidence.
In the Wason task, people tend to check cards that could confirm the rule (like flipping 'A' to see if it has '7') rather than those that could disprove it (like flipping '8' to see if it has 'A').
Studies, like the one with black and white boxes of shapes, show people prefer to test hypotheses by looking for confirming instances, often overlooking the critical counterexamples.
This confirmation bias is deeply ingrained, even affecting scientific inquiry where actively seeking to disprove one's own theories is crucial but not always instinctive.

Confirmation bias significantly hinders objective reasoning and problem-solving by leading us to overlook evidence that contradicts our beliefs or hypotheses.

In the 'all triangles are white' experiment, participants repeatedly asked to see white shapes (which confirmed the rule) instead of black shapes (which could falsify it).

The prevailing theory suggests reasoning evolved not for finding truth, but for social persuasion and cooperation.
We often arrive at conclusions intuitively and then construct reasons to justify them, a concept explored in books like 'The Enigma of Reason'.
Fatic communication, like saying 'How's it going?' or 'You too,' serves to establish social connection and acknowledge presence, rather than convey specific information.
These social functions of language and reasoning are more fundamental to human interaction than abstract logical analysis.

Recognizing reasoning's social function helps explain why we prioritize social harmony and persuasion over objective truth-seeking in many situations.

Responding 'You too' to a waiter saying 'Enjoy your meal' is fatic communication, a social ritual that acknowledges the shared human experience, even if illogical in context.

Many decisions, even those appearing logical, are rooted in emotional responses and social intuition.
The 'deficit model' of public communication, which assumes people lack knowledge and just need facts, is ineffective because it ignores worldviews and social factors.
Moral reasoning, as explored in Jonathan Haidt's work, often involves strong intuitive reactions followed by the construction of post-hoc justifications.
Harmless taboo violations, like eating a dog that died accidentally, feel wrong intuitively even when no harm or logical reason for offense exists.

This highlights that persuasion and understanding are not achieved through pure logic or data alone, but through social connection, shared values, and emotional resonance.

The story of a family eating their dog after it died in a car accident, while logically lacking harm, elicits a strong intuitive negative moral reaction in many people.

Key takeaways

1Abstract reasoning tasks like the Wason selection task are significantly harder than those involving social rules or obligations.
2Our reasoning abilities appear to have evolved primarily to facilitate social cooperation and persuasion, not for abstract truth-finding.
3Confirmation bias, the tendency to seek evidence that supports our existing beliefs, is a powerful cognitive shortcut that often hinders objective analysis.
4Fatic communication, used for social bonding and acknowledgment, is a vital but often unconscious aspect of human interaction.
5Persuasion and decision-making are deeply influenced by intuition, emotion, and social context, rather than solely by logic and data.
6Understanding the social nature of reasoning helps explain phenomena like the ineffectiveness of purely informational approaches to public communication and the persistence of certain beliefs.

Key terms

Wason selection taskConditional statementModus PonensModus TollensAntecedentConsequentDeontic ruleDescriptive ruleConfirmation biasFatic communicationSocial reasoningIntuition

Test your understanding

1Why does the Wason selection task become significantly easier when framed as a social rule (e.g., drinking age) compared to an abstract rule (e.g., letters and numbers)?
2Explain the difference between Modus Ponens and Modus Tollens and how they relate to solving the Wason selection task.
3What is confirmation bias, and how does it lead people to fail the Wason selection task?
4How does the concept of fatic communication illustrate the social function of human language and reasoning?
5According to the social theory of reasoning, why do humans construct reasons to justify conclusions rather than using reasons to arrive at conclusions?