PowerPoint® Presentation by Jim Foley

© 2013 Worth Publishers

Thinking, Language, and

Intelligence

Module 30: Assessing Intelligence

Topics that may test our intelligence

Binet’s mental age test: Predicting school learning challenges

Terman and the Stanford-Binet IQ test: innate intelligence Wechsler tests Aptitude vs. Achievement tests Standardization and Re-Standardization (Flynn Effect) Reliability and Validity Is intelligence stable over the lifespan? Cross-sectional vs. longitudinal studies Extremes of Intelligence

Assessing IntelligenceAssessment refers to the activity and the instruments used to measure intelligence.The challenge is to make these instruments valid (measure what they are supposed to measure) and reliable (yielding the same score if administered again, even if administered by someone else).

to study how (and why) people differ in ability

to match strengths and weaknesses to jobs and school programs

to help the “survival of the fittest” process; trying to select the people who have the greatest abilities. This was the position of eugenicist Francis Galton (1822-1911).

Why Try to Measure Intelligence?

Predicting School Achievement: Alfred Binet

Problem: in the late 1800s, a new law in France required universal education even for those without the ability to succeed with the current instruction.

Solution: Alfred Binet devised tests for children to determine which ones needed help.

Binet hoped to predict a child’s level of success in regular education.

Intelligence: Growing with Age?

Alfred Binet assumed that all children follow the same course of development, some going more quickly, and others more slowly.

Binet’s tests attempted to measure mental age--how far the child had come along on the “normal” developmental pathway.

The implication was that children with lower ability were delayed (with a mental age below their chronological age), and not disabled; with help, they could improve.

Binet Stanford-Binet

William Stern preserved Binet’s comparison of mental to chronological age as: ratio/quotient.

Lewis Terman, of Stanford University, adapted Alfred Binet’s test, adding new test items and extending the age range into adulthood.

Terman also tested many California residents to develop new norms, that is, new information about how people typically performed on the test.

The result was the Stanford-Binet intelligence test.

William Stern’s scoring (1914) of the Stanford-Binet test resulted in the concept of IQ, the Intelligence Quotient.

Binet reported scores as simply one’s mental age; a 10 year old with below average intelligence might have a mental age of 8.

Q: What IQ score do we get for

What do scores mean?

Lewis Terman, of Stanford University, began with a different assumption than Binet; Terman felt that intelligence was unchanging and innate (genetic).

Later, Terman saw how scores can be affected by people’s level of education and their familiarity with the language and culture used in the test.

What to do if you score low on an IQ test?

Binet

Terman

Study, and develop self-discipline and

attention span.

Remove your genes from the

population(eugenics).

IQ

SAT scores (verbal + quantitative)

Aptitude vs. Achievement Achievement tests measure what you already have learned. Examples

include a literacy test, a driver’s license exam, and a final exam in a psychology course.

Aptitude tests attempt to predict your ability to learn new skills. The SAT, ACT, and GRE are supposed to predict your ability to do well in

future academic work.

If the SAT is an aptitude test,

should it correlate with

IQ?

David Wechsler’s Tests: Intelligence PLUSThe Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Intelligence Scale for Children (WISC) measure “g”/IQ and have subscores for:

verbal comprehension.processing speed.perceptual organization.working memory.

In order for intelligence or other psychological tests to generate results that are considered useful, the tests (and their scores) must be:

standardized.

Principles of Test Construction

reliable.

valid.

Many intelligence tests generate a raw score based on the number of answers correct, but can we turn this into a number that tells us how smart/capable a person is compared to the general population?

Standardization

Standardization means defining the meaning of scores based on a comparison with the performance of others who have taken the test before.

William Stern compared our intelligence test score to others by finding a “mental age” of people who scored on average the way we did.A newer method of generating an intelligence test score is to determine where your raw score falls on a distribution of scores by people of your chronological age.

Standardization: How “Normal” is Your Score?

If we stacked a bunch of Weschler Intelligence Tests (by people your age) in a pile placed by raw score (number of test items correct), there would be a few very high scores and a few low scores, and a big pile in the middle; this bell-shaped pile is called the normal curve. We will call the average raw score “IQ 100.”

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Comparing your score to this standard set of

scores: if you score higher than 50

percent of people, you your IQ is 100.

If your score is higher than 98 percent of the

population, your IQ is around what

number?

Re-Standardization and the Flynn EffectRe-Standardization: Re-testing a sample of the general population to make an updated, accurate comparison group, in case people are smarter than they used to be when the test was first made.

The Flynn Effect:

 Performance on intelligence tests has improved over the years, worldwide.

Test your understandingYou took an intelligence test last week and were assigned a number of 120. Then, after decades of the Flynn effect, the test was restandardized this week. Today, you took the same test and got exactly the same number of items correct. Your new intelligence test score is most likely to be:

A. 105B. 120C. 128

A test or other measuring tool is reliable when it generates consistent results.

Reliability and Validity

Split-half reliability: do two halves of the test yield the same results?

Test-retest reliability: will the test give the same result if used again?

If your height was measured with a ruler made of stretchy material, what would be the problem?

A test or measure has validity if it accurately measures what it is supposed to measure. Content validity: the test

correlates well with the relevant criterion, trait, or behavior

Predictive validity: the test predicts future performance (e.g. an aptitude test relates to future grades)

If your height was measured with a yardstick on which the units were too small, what would be the problem?

At the higher range of weights and success, weight is less of a valid predictor of success of football linemen.

Predictive Validity: Only in Broad

Ranges

Dynamics of Intelligence

Are intelligence test scores stable or do they change with

age?

Stability of Intelligence during Aging

Cross-sectional studies examine people of different ages all at once.Older adults do not perform as well as younger adults on intelligence tests.What factors could explain this? What is different about these different populations other than their chronological age?

Evidence for stability

Evidence for change/decline

Longitudinal studies track the performance of one group of people, or cohort, over time.This method yields evidence that intelligence remains stable, or even increases, over time.What could account for this result? What are the shortcomings of this method?

Putting the evidence togetherCan we combine the information on this chart and form a general impression about whether intelligence declines with age?

Stability of Intelligence during Aging

Which type of intelligence?

Stability of Intelligence during Aging:

Based on this chart, at what age might you do best at completing a crossword puzzle quickly?

Fluid and Crystallized Intelligence

Fluid intelligence refers to the ability to think quickly and abstractly.

Crystallized intelligence refers to accumulated wisdom, knowledge, expertise, and vocabulary .

Stability of Intelligence Test ScoresOver the Lifespan

Pushing toddlers to learn does not seem to help much. Only by age four is a child’s performance on intelligence tests a predictor of future performance on intelligence tests.

Based on the results of a longitudinal study depicted in this chart, does intelligence test score at age 11 predict intelligence test score at age 80?

Intelligence and Longevity

In a Scottish longitudinal study, 11-year-olds with higher intelligence test scores lived longer and more independently and were less likely to develop Alzheimer’s Disease.

In a study of nuns , those with lower verbal ability were later more likely to develop Alzheimer’s Disease, which includes a shorter lifespan.

Extremes of Intelligence

The Wechsler Intelligence Scale is set so that about 2 percent of the population is above 130 and about 2 percent of the population is below 70.

Very High Intelligence,

GiftedIntellectual Disability

Extremes of Intelligence

“Intellectual disability” refers to people who have an IQ around 70 or below.have difficulty with adaptive skills, such as:

conceptual skills (literacy and calculation). social skills, including making safe social choices. practical daily living skills such as hygiene, occupational skills, and

using transportation.

Although some people with high intelligence test scores can seem socially delayed or withdrawn, most are “successful.”

“Gifted” children, like any children, learn best with an appropriate level of challenge.

Segregated, “tracked” programs, however, often unfairly widen achievement gaps.