Assessing Intelligence

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• Chapter 11
• Assessing Intelligence

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Origins of Intelligence Testing

• Mental Age
• a measure of intelligence test performance
  devised by Binet
• chronological age that most typically corresponds
  to a given level of performance
• child who does as well as the average 8-year-old
  is said to have a mental age of 8

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Origins of Intelligence Testing

• Stanford-Binet
• the widely used American revision of Binets
  original intelligence test
• revised by Terman at Stanford University

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Origins of Intelligence Testing

• Intelligence Quotient (IQ)
• defined originally the ratio of mental age (ma)
  to chronological age (ca) multiplied by 100
• IQ ma/ca x 100)
• on contemporary tests, the average performance
  for a given age is assigned a score of 100

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Assessing Intelligence

• Aptitude Test
• a test designed to predict a persons future
  performance
• aptitude is the capacity to learn
• Achievement Test
• a test designed to assess what a person has
  learned

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Assessing Intelligence

• Wechsler Adult Intelligence Scale (WAIS)
• most widely used intelligence test
• subtests
• verbal
• performance (nonverbal)

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Assessing Intelligence Sample Items from the WAIS
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Assessing Intelligence

• Standardization
• defining meaningful scores by comparison with the
  performance of a pretested standardization
  group
• Normal Curve
• the symmetrical bell-shaped curve that describes
  the distribution of many physical and
  psychological attributes
• most scores fall near the average, and fewer and
  fewer scores lie near the extremes

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The Normal Curve
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Getting Smarter?
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Assessing Intelligence

• Reliability
• the extent to which a test yields consistent
  results
• assessed by consistency of scores on
• two halves of the test
• alternate forms of the test
• retesting
• Validity
• the extent to which a test measures or predicts
  what it is supposed to

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Assessing Intelligence

• Content Validity
• the extent to which a test samples the behavior
  that is of interest
• driving test that samples driving tasks
• Criterion
• behavior (such as college grades) that a test
  (such as the SAT) is designed to predict
• the measure used in defining whether the test has
  predictive validity

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Assessing Intelligence

• Predictive Validity
• success with which a test predicts the behavior
  it is designed to predict
• assessed by computing the correlation between
  test scores and the criterion behavior
• also called criterion-related validity

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Assessing Intelligence

• As the range of data under consideration narrows,
  its predictive power diminishes

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The Dynamics of Intelligence

• Mental Retardation
• a condition of limited mental ability
• indicated by an intelligence score below 70
• produces difficulty in adapting to the demands of
  life
• varies from mild to profound
• Down Syndrome
• retardation and associated physical disorders
  caused by an extra chromosome in ones genetic
  makeup

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The Dynamics of Intelligence