IQ and Personality Assessment
Psychology 631
William P. Wattles, Ph. D.
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Exam One
• Why is the mean or average alone not
enough information to describe a
distribution?
• The mean doesn’t tell us about the
variability, that is how spread out the data
are.
2
Exam One Make-up
• Why do we need to calculate the standard
deviation?
• It tells us about the variability, that is how
spread out the data are.
3
Exam Two
• Jen reports means for different groups in her
research. Should she also report the
standard deviation? If so why?
• Yes, It tells us about the variability, that is
how spread out the data are.
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5
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• Intelligence is a very
difficult concept to
define. Intellect is
described as “the
power of the mind to
think in a logical
manner and acquire
knowledge”
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Wechsler Scales
• Sound psychometrics
– Long and extensive
history of continued
evaluation
• Produce relevant
information
8
IQ tests
• Assess individual’s
relative strengths and
weaknesses
• Compare with peers
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Accuracy of Prediction
• One of the main assets of intelligence tests
is their accuracy in predicting future
behavior.
• Academic achievement
• Occupational performance
• Neuropsychology deficits
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Correlation with IQ
•
•
•
•
Success for
Managers .53
Salespersons .61
Clerks .54
• For intellectually
demanding jobs nearly
half the variance can
be explained by IQ
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Personality variables and IQ
• Poor scores on digit
span, arithmetic and
digit symbol suggest
anxiety or ADHD.
• High on
Comprehension and
Picture arrangement
suggests good social
judgment
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Problems with IQ
• Does not measure
fixed innate ability
• Does not measure all
cognitive abilities
• Easily misused
• Highly personal
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Creativity
WAIS-3 Emphasizes
• Convergent
• Analytical
• Scientific modes of
thought
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Prediction
• Base line rates
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• Predictor variable
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Probabilistic Reasoning
• “The Achilles’ heel of
human cognition.”
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Probabilistic Reasoning
• “Men are taller than
women”
• “All men are taller
than all women”
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Probabilistic Reasoning
• A probabilistic trend
means that it is more
likely than not but
does not always hold
true.
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Probabilistic Reasoning
• “The Land of
sometimes and
perhaps”
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Probabilistic Reasoning
• Knowledge does not
have to be certain to
be useful.
• Individual cases
cannot be predicted
but trends can
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Intelligence in assessment
• Intelligence exists
• Can improve
understanding
• It is part of the person.
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Interpreting the WAIS-III
• Full Scale IQ, the single most valid and
reliable scale.
• Percentile scores or intelligence
classification may be harder to misuse.
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Intelligence Classifications
>129
120-129
110-119
90-109
80-89
70-79
<70
Higher extreme above average
Well above average
high average
average
low average
well below average
Lower extreme below average
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Percentile Rank examples
IQ
130
120
110
100
90
80
70
60
Percentile
98.0%
91.0%
75.0%
50.0%
27.0%
9.0%
2.0%
0.4%
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• Work Satisfaction
– Fit between ability and job
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• Compatibility in relationships
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• Leisure time pursuits
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• Example of behavior when person is
distracted from being conscious of being
watched.
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The End
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