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Decision Making and Reasoning


Decision Making and Reasoning ... Term introduced by Herbert A. Simon in his Models of Man 1957 Simon noted that humans are rational but within limits ... – PowerPoint PPT presentation

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Title: Decision Making and Reasoning

Decision Making and Reasoning
  • Models of Decision Making/Reasoning
  • Biases in decision making
  • Confirmation bias seen in .
  • The use of heuristics in decision making/
  • A heuristic is a guiding ............ or
    .............. used in solving problems or making

Models of Decision Making
  • 2 different types of models for decision making
  • Prescriptive models
  • ..
  • ..
  • Descriptive models
  • Models describing the way decisions are actually
  • Cognitive psychologists are interested in how
    people .

High effort multi-attribute decision-making
Low effort use of heuristics
A Prescriptive ModelClassical Decision Theory
  • Assumed decision makers
  • Knew all the options available
  • Understood pros and cons of each option
  • Rationally made their final choice
  • Goal was to maximize value of decision

A descriptive modelSatisficing
  • To obtain an outcome that is
  • Term introduced by Herbert A. Simon in his Models
    of Man 1957
  • Simon noted that humans are rational but within
    limits (bounded rationality)

Effort and Decision Making
  • High effort multi-attribute decision-making
  • Low effort use of .....................
  • Heuristics can be accurate in some situations.
  • But can also lead to .

Heuristics Influencing Decision Making/Reasoning
  • Representativeness
  • Availability
  • Illusory correlation
  • Confirmation Bias

Representativeness Heuristic
  • Judgments strategy in which we make estimates of
    how similar (or representative) an
  • An object is judged by similarity, i.e. the
    degree to
  • which the object resembles a
  • Coin toss Which outcome is more representative
    (more likely)?
  • H H H H H H
  • H T H T H T

Representativeness Heuristic
  • Can be accurate
  • Can also
  • Kahneman Tversky (1972)
  • In general population birth rates are about 50
    boys and 50 girls.
  • There is a big hospital in a city (45 births per
    day), and a small hospital in a town (15 births
    per day)
  • For a period of 1 year, both the larger hospital
    and the smaller hospital recorded the number of
    days on which gt 60 of the boys born were boys.
  • Which hospital recorded more such days
  • Big hospital
  • Small hospital
  • About the same

Representativeness and the Gamblers Fallacy
  • Suppose you are at a roulette wheel and the last
    8 spins have come up red.
  • Do you bet on red or on black for the next spin?
  • Red and black are
  • No statistical reason to select .

Availability Heuristic
  • In the English language, are there more words
    beginning with the letter K or more words with K
    in the third position?
  • People often report 2 x as many words beginning
    with K
  • But there are

Availability Heuristic
  • The ease of bringing an example to mind is a
    means of estimating
  • An event is judged by accessibility, i.e. by the
    ease with which instances are .
  • Bias -- tendency to overestimate rare events

Availability Heuristic
  • Actual frequency influences how easily evidence
    comes to mind but so do other factors
  • .
  • - Media more likely to report sensational events
    such as hurricanes, terrorist acts, airplane
  • People are more likely to think they will die
    from rare causes (airplane crash) than common
    causes (automobile accident)
  • Famous vs. not so famous names study (Tversky).
  • Ps given names of 19 famous people and 20
    not-so-famous people.
  • Later asked which type of name had occurred more
  • Most Ps said ..

Illusory Correlations
  • An illusory correlation is a perceived
    relationship that does not in fact .
  • Illusory correlations are formed by the pairing
    of two distinctive events
  • Redelmeier and Tversky (1996)
  • 18 arthritis patients observed over 15 months
  • The weather was also recorded
  • Most of the patients were certain that their
    condition was correlated with the weather
  • The actual correlation was .
  • What illusory correlations may affect your

Confirmation Bias
  • Confirmation bias -- tendency to seek (and find)
    information that

Confirmation Bias and the Wason Selection Task
  • Which cards do you need to turn over to obtain
    conclusive evidence of the following rule A
    card with a vowel on it will have an even number
    on the other sideE K 4 7

Logical Reasoning
  • A card with a vowel on it will have an even
    number on the other sideE K 4 7
  • Answer
  • E -- search for positive evidence
  • 4 only search for positive .
  • 33 say E only (missing .
  • 46 say E 4
  • 4 is

Wason Selection Task (continued)
  • People do better on this task if it is placed in
    an everyday ..
  • Task Pick cards that need to be looked at to
  • If the person is drinking a beer then the person
    must be over 19 yrs. old
  • Drinking a beer 16 years old Drinking a
    coke 22 years old

  • Research has demonstrated a number of errors in
    reasoning/decision making based on the use of
  • Also logical errors as in the Wason selection
  • We may not be as rational as we like to think we

A cautionary note
  • While research shows that biases and errors are
    common in human decision making, some
    psychologists argue that this is due to the
    laboratory tasks used.
  • Evolutionary psychologists argue that traditional
    decision research has imposed an unrealistic
    standard in that questions are asked in ways that
    have nothing to do with the adaptive problems
    that humans have evolved to solve.
  • Consistent with this theory, many reasoning
    errors disappear when problems are presented in
    ways that resemble ...............................

Cautions (continued)
  • Gigerenzer (2000) argues that humans do not have
    the time, resources, or capacities to gather all
    information, consider all alternatives, calculate
    all probabilities and risks, and then make the
    statistically optimal decision.
  • Instead, we use the fast and frugal route, making
    quick, one-reason decisions which yield
    inferences that are often just as accurate as
    much more elaborate and time-consuming