Thinking through Decisions Memory and Language

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Thinking through Decisions(Memory and Language)

• PS 111 Spring 2007
• March 21, 2007

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Implicit and Explicit Tests of Memory

• Free Recall
• Cued Recall
• Recognition
• Word stem completion
• Word fragment completion
• Perceptual Identification

Explicit
CHA___
Implicit
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(No Transcript)
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Language Perception and Comprehension
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The procedure is actually quite simple. First
you arrange items into different groups. Of
course one pile may be sufficient depending on
how much there is to do. If you have to go
somewhere else due to lack of facilities that is
the next step otherwise, you are pretty well
set. It is important not to overdo things. That
is, it is better to do too few things at once
than too many. In the short run this may not
seem important but complications can easily
arise. A mistake can be expensive as well. At
first, the whole procedure will seem complicated.
Soon, however, it will become just another facet
of life. It is difficult to foresee any end to
the necessity for this task in the immediate
future, but then, one never can tell. After the
procedure is completed one arranges the materials
into different groups again. Then they can be
put into their appropriate places. Eventually
they will be used once more and the whole cycle
will then have to be repeated. However, that is
a part of life. (Bransford Johnson, 1972)
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Bransford and Johnson (1972)Comprehension
Recall in a familiar context
2.3 2.8
4.5 5.3
2.1 2.7
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How Do We Understand Language

• Form a coherent mental representation
• Inference generation
• Role of context

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Inference Generation

• inferences integrate information from the text
  with knowledge (e.g. scripts)
• inferences are used to construct a coherent
  mental representation
• inferences are used to construct the meaning of a
  text

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instrument inference

• The man swept the floor.
• --gt broom
• Inferences made about the thing (the instrument)
  used to perform the action

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Judgment and Decision Making
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Representative Heuristic Base Rates

• Steve is very shy and withdrawn, invariably
  helpful, but with little interest in
• people or the world of reality. A meek and tidy
  soul, he has a need for order
• and structure, and a passion for detail.
• How likely is it that Steve is a librarian? A
  farmer?
• If you guessed farmer because there are more
  farmers than librarians,
• You were using base rate or prior probability
• If you didnt,
• You were showing base rate neglect

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What is a heuristic?

• Mental shortcut used in judgment and decision
  -making
• essential for living in an uncertain world
• but can lead to faulty beliefs and suboptimal
  decisions
• Optimizing vs. satisficing

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Base Rates
The use of base rates is critical in everyday
reading of statistics "our circulation has
doubled in the last year, making it the fastest
growing magazine in the country." (But they only
had 4 readers)

Base rate information Overall likelihood that a
particular case will be in one category or another
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Inverse Error Due to Base Rate Neglect
P( Characteristics Librarian)
does NOT equal P( Librarian Characteristics)
P(CL) P(C and L)/P(L) P(LC) P(C and
L)/P(C) The two are equal only if base-rates are
equal


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Need to Account for Prevalence

Mamogram indicates Cancer No cancer
Total
Mamogram indicates Cancer No cancer
Total
Cancer
No Cancer
Baserate .01
P (CM) 850/(850 9,900)
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Availability

• Making judgments about the frequency or
  likelihood of an event based on the ease with
  which evidence or examples come to mind
• Actual frequency certainly influences how easily
  evidence comes to mind, but other factors play a
  role as well.

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We use the heuristics because they usually work

• Are there more words that begin with the letter r
  or have r as the 3rd letter?

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Sources of inappropriate bias in using
availability

• Vividness (and memory factors in general)
• Ease with which cues bring examples to mind
• Unrepresentative experience

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Another influence on availability Media Coverage
and bad news bias

• Plane crashes
• It's 22 times safer flying in a commercial jet
  than traveling by car (comparing accident
  fatalities per million passenger-miles traveled
  in the U.S.)
• More than 3,000,000 people fly safely on
  commercial airliners world-wide each day.
• Stranger abductions
• less than 1 of the 800,000 children abducted in
  2001 were abducted by strangers
• "It strikes at your fears. When you have
  children, you worry about them ... When are you
  ever safe? The media and people seem to get off
  on the fear. ... The media love to play with
  anything that gets people excited.
• Will C. Kennedy

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Impact on risk assessment
Which in each pair causes more deaths per year?
Stomach Cancer vs. Motor Vehicle
Accidents Tuberculosis vs. Fire and Flames
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Impact on risk assessment
Which causes more deaths per year?
(Russo Shoemaker, 1989)