PSC 1 Lecture Notes - Lecture 12: Mental Age, Intellectual Disability, Twin
Intelligence
What is intelligence?
• Intelligence is what intelligence tests measure
What do intelligence test measure?
• Basic concepts in measurements
o Reliability
• When a test produces the same scores under the same conditions
• Unreliability: conditions stay the same, but score changes.
o Validity
• The measure is reliable
• But not valid
• Construct validity: a test measures what it claims to measure
• If test is valid, its scores should correlate with other measures of the same
construct
• E.g. Scholastic achievement
• Academic tests
â–Ş SAT
â–Ş CAT
• Correlates
â–Ş Grades
â–Ş Grade-level
• Predictive validity: scores at one time predict at a future time. Allows to predict
future results.
o Distributions
• Measures of central tendency: mean, median and mode
• Variability
How do IQ tests work?
Developed by Alfred Binet
• Step 1: test a large number of people
o Norming sample
o Result: A distribution
• Some perform low, most in the middle and some high. So we get a distribution
of results.
• Testing intelligence depends on distribution
• Affected by:
• variability
• Interpreting scores that assumes that your test is reliable
• Step 2: is the test reliable?
o Split- half: scores on one half compared to the other half
o Test -Retest: two or more separate testing sessions.
• Test 1 and 2 results line up.
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• Step 3: is your test valid?
o Does it have construct and predictive validity?
What is IQ (Intelligence Quotient)?
• IQ- ["mental age"/age] x 100
• Mental age:
o Step 1: Test many kids
o Step 2 : identify items that discriminate e between ages
• E.g.: a 5 yo get them right but not 4 yo.
o Step 3: test an individual kid.
• Deviation IQ
o Measure of an individual's generalized intelligence. analyzes a person's intelligence
relative to their age.
o Test only same age people
o You get a distribution
Why use Intelligence tests?
• Predictive validity
o IQ tests can identify children with mental retardation
o Intelligence tests predict achievement in school.
One intelligence (G) or many?
• G: one factor accounts for performance on numerous sub tests
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find more resources at oneclass.com
