Mar 21 Reasoning

• Event Boundaries: physical Boundaries (doorways) and Scenarios (before/after an exam) define separate events in episodic memory
• We forget items immediately after crossing an event boundary

• Doorway Effect: why we forget what we were thinking about upon entering a different room
• Scenario Boundary: why you may forget information before an exam
• Neuroeconomics: studying how we make decisions, formalizing theories and linking it to the development of the brain
• Heuristics: generalizations that we apply when reasoning

  • help us save on information processing
  • when over-applied, biases occur
• Biases: systematically inaccurate choices that don't reflect a current situation
• Representativeness Bias: probability that an item (person, object, event) is a member of a category because it resembles that category

  • idea that what we are observing, we try and match to categories/concepts we have in mind
  • overuse can lead to stereotyping, base-rate neglect, and conjunction fallacy
• Availability Bias: the easier it is to remember something, the more likely you'll think it is to happen in the future (memory-based bias)

  • we confuse the availability of a memory with frequency
  • ex. seeing things on news often makes you think it happens a lot more than it does
• Illusory Correlations: linking two co-occurring events and assuming a relationship
• Anchoring & Adjustment Heuristic: we are biased by initial value, so we adjust our assessment/value of the situation based on that initial anchor (mark)
• Gambler's Fallacy: false idea that whatever came before, even if random, will influence outcome of next

  • we assume outcomes are linked when they are random
  • relates to illusory correlation
• Hot Hand Belief: Thinking that a person who experiences success will keep having success

  • i.e. a 'winning streak'
• Heuristic processing is central for making intuitive and rapid judgments
• Over-application of heuristics can lead to serious errors in our judgments and reasoning
• Errors from over-reliance on heuristics

  • Stereotyping, Gambling addictions
• Post-mortem technique: learning from failures
• Pre-mortem technique: anticipating and preventing mistakes before they result in catastrophe

  • we imagine what could go wrong and identify how not to fall into that trap
• Inductive Reasoning: making general conclusions from specific observations

  • moves from specific observations to broader generalizations
  • reasoning with information
  • probable form of reasoning
  • when we are unaware of inductive reasoning, it can become availability heuristics
• Inductive reasoning conclusions can be false, thus is a "probably but not definitely true" type of reasoning
• Deductive Reasoning: using general theories to reason about specific observations

  • moves from broad generalizations to specific conclusions
  • ex. "All men are mortal. Socrates is a man. Therefore, Socrates is mortal."
• Inductive vs Deductive Reasoning

  • Inductive is concrete, Deductive is abstract
  • Inductive develops earlier (age 7-11), Deductive develops later (teenage years)
  • Inductive relies more on frontal cortex, Deductive relies on different brain networks
• System 1 vs System 2 Reasoning

  • System 1: automatic and effortless (inductive)
  • System 2: slower and requires more effort (deductive)
• Syllogisms: premises are presumed to be tru and will give information about

  • Major Premise (general) ex. all dogs are animals
  • Minor Premise (specific) ex. all animals have 4 legs
  • Conclusion (test) ex. thus all dogs have 4 legs
• Validity of Syllogisms


  Is the conclusion true given the premises' logical form?
• Types of Syllogisms

  • All Statements: All A are B
  • Negative Statements: No A is a B
  • Some Statements: Some A are B
• Atmosphere Effect: people rate a conclusion as valid when the qualifying word (e.g. 'all,' 'some') in the premise match those in the conclusion

  • we turn to our mood and what feels right to direct our thinking
• Mental Model Theory: people construct mental simulations of the world based on statements (e.g. syllogisms) to judge logic and validity

  • we can't imagine negative statements
• Omission Bias: people tend to have more trouble reasoning with negative information

  • inaction is harder to classify as wrong than action
• The Trolley Problem


  • Do nothing and kill 5 people, switch the train to another track and kill 1 person, stop the trolley and save the 5 people by pushing a large man to his death
  • although C is a utilitarian response, many do not choose C due to adverse emotion
• Ventromedial Prefrontal Lesions: less emotional response leads to more utilitarian response
• Belief Bias: the tendency to think a syllogism is valid if the conclusions are believable, even if it is logically invalid

  • if you believe something to be true, you are more likely to think the syllogistic argument is logical even if it isn't
• Syllogisms structure measures logical reasoning

  • incorrectly assessing syllogisms shows when we deviate from logical reasoning
• High-Functioning Autism: differences in emotional processing leads to more utilitarian response
• Wason's Task


  Testing the conditional statement "If a card has a vowel on one side, then it has an even number on the other side"
• Positive Emotion Induction: healthy individuals with heightened positive mood are more likely to say they would push the man (utilitarian response) than control group in trolley problem
• Falsification Principle: look for situations that would falsify a rule
• The Return Trip Effect: time judged returning on a route (now familiar) is rated as shorter than initial route
• Familiarity affects our judgment, even of time (the Return Trip Effect)
• our memories (challenges) are recalled easier than other people's memories experiences

  • thus making us think we have it harder than others