Reasoning and Decision Making or The Shortcuts of the Human Mind (a.k.a Heuristics) by Elan Dubrofsky and Dina Tsirlin

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Reasoning and Decision MakingorThe Shortcuts of
the Human Mind(a.k.a Heuristics)by Elan
Dubrofsky and Dina Tsirlin
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Reasoning

• Cognitive processes by which people start with
  information and come to conclusions that go
  beyond that information

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Deductive Reasoning

• Syllogism
• Two statements called premises
• Third statement called conclusion
• Categorical Syllogism
• Describe relation between two categories using
  all, no, or some
• Premise 1 All computer scientists are nerds.
• Premise 2 All nerds can name all six Star Wars
  movies.
• Conclusion All computer scientists can name all
  six Star War movies.

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Deductive Reasoning

• Syllogism is valid if conclusion follows
  logically from its two premises
• Aristotles perfect syllogism
• Premise 1 All A are B
• Premise 2 All B are C
• Conclusion Therefore, All A are C

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Deductive Reasoning

• If two premises of a valid syllogism are true,
  the syllogisms conclusion must be true.
• Do not confuse validity with truth
• The following syllogism is valid but not true
• All birds are animals
• All animals have four legs
• All birds have four legs

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How Well Can People Judge Validity?

• Errors in evaluation
• Atmosphere effect use of words all, some or
  no in premises increase the probability of a
  conclusion with those words

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Belief bias if syllogism is true or agrees with
a persons beliefs, more likely to be judged valid
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• How do people go about determining whether a
  syllogism is valid/invalid?

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Mental Models of Deductive Reasoning

• Specific situation that is represented in a
  persons mind that can be used to help determine
  the validity of syllogisms
• Iterative process
• Look for exceptions
• if no exception accept model and establish
  validity
• if exception modify the model until can be
  satisfied

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Deductive Reasoning

• Conditional syllogisms
• If p, then q.
• If I lend Emt 20, Then I wont get it back.
• I lent Emt 20. Therefore, I wont get my 20
  back
• Four types of conditional syllogisms
• Affirming the antecedent
• Denying the consequent
• Affirming the consequent
• Denying the antecedent

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The Wason Four-Card Problem

• Effect of using real-world items in a
  conditional-reasoning problem
• Determine minimum number of cards to turn over to
  test If there is a vowel on one side, then there
  is an even number on the other side.

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• Caption The Wason four-card problem (Wason,
  1966).

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The Wason Four-Card Problem

• Falsification principle to test a rule, you must
  look for situations that falsify the rule
  (exception)
• Most participants fail to do this
• When problem is stated in concrete everyday
  terms, correct responses greatly increase

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The Wason Four-Card Problem

• Pragmatic reasoning schema thinking about cause
  and effect in the world as part of experiencing
  everyday life
• Permission schema if A is satisfied, B can be
  carried out
• Used in the concrete versions
• People are familiar with rules

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Evolutionary Perspective on Cognition

• Evolutionary principles of natural selection
• Wason task governed by built-in cognitive program
  for detecting cheating

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Evolutionary Perspective on Cognition

• Cosmides and Tooby (1992)
• Created unfamiliar situations where cheating
  could occur
• Participants did well
• Evidence against permission schema

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Inductive Reasoning

• Premises are based on observation and we
  generalize from these cases to more general
  conclusions with varying degrees of certainty

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Inductive Reasoning

• Strength of argument
• Representativeness of observations
• Number of observations
• Quality of observations

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ACTIVITY Which argument is stronger? Why?

1. Observation All sushi places Ive seen in
   Vancouver charge a lot for sashimi. When I
   visited my family in Ottawa, the sashimi was
   expensive too. Conclusion All sushi
   places charge a lot for sashimi.
2. Observation Here in Ottawa, the sun has risen
   every morning. Conclusion The sun is
   going to rise in Ottawa tomorrow.

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Inductive Reasoning

• Used to make scientific discoveries
• Hypotheses and general conclusions
• Used in everyday life
• Make a prediction about what will happen based on
  observation about what has happened in the past

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Heuristics

• Availability heuristic events more easily
  remembered are judged as being more probable than
  those less easily remembered
• Is it easier to die for car accident of plane
  crash?

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• Caption Likely-causes-of-death experiment
  results. Pairs of causes of death are listed
  below the graph, with the least likely cause on
  the left. The number in parentheses on the right
  indicates how many more times more people were
  actually killed by the cause on the right. The
  bars in the graph indicate the number of people
  who judged the least likely alternative in each
  pair as causing the most deaths. (Adapted from
  Lichtenstein et al., 1978).

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Heuristics

• Illusory correlations correlation appears to
  exist, but either does not exist or is much
  weaker than assumed
• Stereotypes

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A little experiment...

• Rate info Among 100 people, 70 are lawyers, 30
  are engineers

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A little experiment...

• Description Jack, 45 yrs old, 4 kids,
  conservative, careful. Not interested in
  politics, many hobbies math puzzles carpentry
  Lawyer or engineer?

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Heuristics

• Representativeness Heuristic the probability
  that A comes from B can be determined by how well
  A resembles properties of B
• Use base rate information if it is all that is
  available
• Use descriptive information if available and
  disregard base rate information

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Heuristics

• Violation of Conjunction rule
• Conjunction rule probability of two events
  cannot be higher than the probability of the
  single constituents

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• Caption Because feminist bank tellers are a
  subset of bank tellers, it is always more likely
  that someone is a bank teller than a feminist
  bank teller.

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Heuristics

• The Confirmation Bias tendency to selectively
  look for information that conforms to our
  hypothesis and overlook information that argues
  against it

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Heuristics

• The Confirmation Bias
• Lord and coworkers (1979)
• Had those in favor of capital punishment and
  those against capital punishment read the same
  article
• Those in favor found the article in favor
• Those against found the article against

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Decision Making

• Economic utility theory
• People are rational and if they have all relevant
  information they will make a decision which
  results in the maximum expected utility

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Decision Making

• Utility outcomes that are desirable because they
  are in the persons best interest
• Maximum monetary payoff

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Decision Making

• Problems for Utility Approach
• Not necessarily money, people find value in other
  things
• Many decisions involve payoffs that cannot be
  calculated
• Good enough philosophy (Herb Simon,
  Psychologist Nobel Prize!!!)

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• Caption Behavioral results of Sanfey and
  coworkers (2003) experiment, showing responders
  acceptance rates in response to different offers
  made by human partners and computer partners.

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Decision Making

• Focusing illusion focus on just one aspect of
  situation and ignore other aspects that may be
  important
• Dating and happiness
• California versus Midwest living

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Decision Making

• Decisions depend on how choices are presented
• Opt-in procedure
• active step to be organ donor
• Opt-out procedure
• Organ donor unless request not to be
• Subjects consent to research participation
• Active Consent
• Passive consent

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Decision Making

• Risky decisions
• Risk-aversion strategy used when problem is
  stated in terms of gains
• Risk-taking strategy when problem is stated in
  terms of losses

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Decision Making

• Framing effect decisions are influenced by how a
  decisions is stated
• Can highlight one aspect of situation

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Decision Making

• Decision-making process includes looking for
  justification so a rationale presented with
  decision

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Decision Making

• Tversky and Shafir (1992)
• pass - go on trip
• fail - do not
• I dont know yet wait to find out results
  before making decision to go on trip or not

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In Conclusion...

• We're only human... therefore our thinking is
  very flawed.
• Be careful to make sure that when you use a
  heuristic, it's not leading you down a dangerous
  path.