WEEK 3 – Judgement and Reasoning

• Judgement


  A mental process by which we come to form beliefs about the world around us
• Forming judgement


  Precursors to making decisions
• Research shows that the rational, exhaustive, probabilistic, mathematical way of forming judgements is not common
• Heuristics


  Mental rules of thumb giving us shortcuts to making decisions that do not involve too much mental effort
• Many judgements made in everyday lives are formed on basis of heuristics
• What is probability distortion? People’s tendency to over-weight relatively rare events in their decision making and underweight relatively common events

  
• Shape of probability distortion

   

  e.g. a day at the beach, people more likely to overestimate likelihood of shark attack and underestimate likelihood of sunburn

  
• Why does probability distortion occur? Availability heuristic + other places
• What is illusory correlations? When people perceive a relationship between 2 variables (events or behaviours) where no relationship truly exists

  e.g. walking under lamppost and the light turns on right away having impression that it is because you walked by, that it turned on
• What is an outcome of illusory correlations? Superstitions

  e.g. eagles fan ran into pillar, eagles won after  man now runs into pillars before each eagle’s game in hopes they win
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  What happens when illusory correlations are applied to social groups? Can manifest as stereotypes.
• What is a stereotype? An illusory correlation between a social group and certain attributes/ behaviours
• Are stereotypes self-reinforcing? Yes, hard to dislodge if presence of stereotype or illusory correlation changes the way people interpret future information
• What is confirmation bias? Tendency to seek out and interpret information in a way that confirms a statement or hypothesis
• How does Confirmation Bias lead to bias judgement?

  Disconfirming evidence is typically much more useful in determining whether a hypothesis is supported, but we tend not to pay attention to this.

  When interpreting ambiguous information, we tend to interpret in a way that supports our existing beliefs
• What is base rate neglect? When we ignore underlying probabilities of events when considering event likelihood
• While the event is equally consistent with both probabilities (both events can cause headaches), scenario 2/ has a lower base rate thus we should think of scenario 1/

   
• What is base-rate fallacy? Worrying too much about scenario 2/, as she ignores base rate information and only paying attention to information that worries her
• What does it mean to draw conclusions from small samples? Frequent error of judgement to assume small sample size is representative of population that they are sampled from
• How do we avoid drawing incorrect conclusions from small samples? Take large samples from population before statistics of sample become similar to statistics of population even when sample is representative of population
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  What does it mean that biases are ubiquitous? We are all subject to them

  -              Awareness of blind spots can help us overcome them
• How do we draw valid conclusions about a population? Sample must be representative of the population thus accurate distributions of age, gender, locality, SES

   
• What is reasoning? Ways in which we draw inferences and conclusions about the world

  -              Mental processes which lead to valid conclusions

  -              Judgement studies processes that lead to error
• What is deductive reasoning? Process of drawing conclusions from premises by constructing valid arguments

  -              Includes using formal rules of proof to reason about syllogisms
• What are properties of deductive reasoning?

  -              Conclusions can be drawn with certainty (100% true or 100% false)

  -              Involves applying a general rule to specific case to draw specific conclusion

  -              Does not add new knowledge

  -              If premise 1 and premise 2 are true, the conclusion MUST be true
• What is a conditional syllogism? Deductive reasoning problem where one premise (the major premise) has the form ‘if P then Q’
• The second premise (minor premise) affirms or denies either the antecedent or the consequent
• What is the modus ponens conditional syllogism? The minor premise affirms the antecedent. These syllogisms are VALID
• What is an INVALID modus ponens conditional syllogism? Affirming the consequent
• What is modus tollens condition syllogism? The minor premise denies the consequent
• What is an INVALID modus tollens condition syllogism? Denying the antecedent
• -              Valid syllogisms are easier to reason about than invalid

  -              Within valid syllogisms, affirming the antecedent is easier to reason about than denying the consequent

   
• How is conditional syllogism a tool for reasoning?

  -              Strongest way to test conditional rule is to seek out disconfirming evidence

  -              Thus we should test a rule by BOTH affirming antecedent and denying consequent

   
• What did Wason’s selection task show?-              All cards had letters on one side and numbers on the other side

   

   

   

  -              Asked participants were asked to test rule that vowel cards had even numbers

  -              Which cards should they turn over to test this rule? Letter A and number 7

   

  
• Why should we turn over card A and 7?

   

  Premise = if there is a vowel on one side (P), then there is an even number on the other side (Q)   affirming antecedent to give a VALID conclusion

   

  Premise = if there is a vowel on one side (P), then there is an even number on the other side (Q). Q is not the case (no even number on the other side), therefore P is not the case  seeking disconfirming evidence to give a VALID conclusion
• Why is turning over 4 not valid? No rule saying that even numbers had vowels on the other side, rather that vowel cards MUST have even numbers on the back (so consonants could be on the other side of even numbers too)
• What is inductive reasoning? Process of drawing general conclusions from specific observations
• What are properties of deductive reasoning?

  -              Don’t draw conclusion with certainty, they are only probably true

  -              Adds new knowledge  involves coming up with general rule to explain set of specific observations

  -              Involves using specific observation to draw conclusion about a general rule

   

  e.g. observation  all people throughout history eventually died

  conclusion  all humans are mortal (only probably true, as new science may make humans immortal)
• What does it mean for inductive reasoning to lead to probably-true conclusions?

  -              Conclusions are produced based from observations thus ALWAYS a probability a new observation will prove previous conclusion false

   
• What are disconfirming observations sometimes called? Black Swans