Measuring Intelligence Intelligence tests try to measure general mental abilities not “book smarts” or knowledge in a specific area

Origins of Intelligence Testing: Alfred Binet

Binet’s “Mental Age” Hired by the French government to develop a test to determine students who had special needs. His test focused on mental abilities like memory, attention, and the ability to understand similarities and differences NOT math and reading. Arranged questions in order of difficulty with simplest first. Compared student’s performance with those of other kids their age. Developed the term, “mental age” which meant the age of the child’s mental abilities. A seven year old operating at a 9 year old’s level would have a mental age of 9. Binet never meant for his test to be used to measure intelligence. He only wanted to identify kids with special needs. He felt intelligence was too complex to capture in a test.

Intelligence Testing: Lewis Terman ( )

Lewis Terman  Found that intelligence alone is not enough to be a success.  Only those that had personality factors that were more goal- oriented, greater perseverance, energetic, conscientious, well- connected = Grit.  Essentially, those with a willingness to work hard were successful. Intelligence is no guarantee of success in professional life. Terman believed that IQ was a fixed, inborn characteristic and would equate in to school success (this against what Binet believed). Terman did a longitudinal study of children whose average IQ scores were 150 (140 is genius level).

Lewis Terman & William Stern Stanford-Binet IQ Test Stanford-Binet Intelligence Test IQ=(MA/CA)*100 IQ=Intelligence Quotient MA=Mental Age CA=Chronological Age A score of 100 would be considered average Formula has been replaced with modern versions Intelligence Quotient - The number that results from Terman and Stern’s formula for computing the level of a person’s intelligence

Calculating Intelligence For an average 7 yr old… MA=7 CA=7 IQ=(MA/CA)*100 IQ=(7/7)*100 IQ=1*100 IQ=100 (average)

Calculating Intelligence For an average 11 yr old… MA=11 CA=11 IQ=(MA/CA)*100 IQ=(11/11)*100 IQ=1*100 IQ=100

Calculating Intelligence For an above average 10 yr old… MA=12 CA=10 IQ=(MA/CA)*100 IQ=(12/10)*100 IQ=1.2*100 IQ=120

Calculating Intelligence For a below average 8 yr old… MA=6 CA=8 IQ=(MA/CA)*100 IQ=(6/8)*100 IQ=.75*100 IQ=75

Calculating Intelligence A glitch… MA levels off at about 18 Average 18 yr old MA=18 CA=18 IQ=(18/18)*100 IQ=(1/1)*100=100 Average 36 yr old MA=18 CA=36 IQ=(18/36)*100 IQ=(1/2)*100=50

Problems with Intelligence Testing Army Alpha written test and the Army Beta oral test used in WWI to test the IQ of recruits and draftees. These later used by immigration and resulted in certain nationalities being labeled as “unfit” resulting in quotas. Play “Pros and Cons of Intelligence Tests” (6:29) Segment #17 from Psychology: The Human Experience. –This is a good review of what you’ve read and highlights how IQ tests have been used in a variety of ways by the government and other agencies.

How Much Stock can we put into IQ Scores? Not too much. To regard an abstract concept as if it were a real, concrete thing is called reification.

Modern Intelligence Tests

Types of Tests Achievement test—designed to measure level of knowledge, skill, or accomplishment in a particular area –classroom tests at the end of a unit Aptitude test—designed to predict your ability to learn a new skill –ACT and SAT Interest test—measures self-reported vocational interests and skills –PLAN Test

David Wechsler ( ) Developed the Wechsler intelligence scales which included: –Different tests for different age groups –Separate verbal and nonverbal scores –Subtests and subtest scores

The Wechsler tests Modeled after Binet’s but improved it in two ways. 1.Designed test for both adults and children. –WISC-IV = Wechsler Intelligence Scale for children –WAIS-IV = Wechsler Adult Intelligence Scale 2.Provided scores in 11 different subtests for 11 abilities which were grouped to show a performance and verbal score. It showed an individual’s strengths and weaknesses in a variety of areas.

The Subtests of the Wechsler Test and how they’re used Verbal score – obtained from subtests in vocab, comprehension, knowledge and general info. Performance score – obtained by nonverbal subtests like identifying the missing part in a picture, arranging pictures into a story, arranging blocks to match a pattern. Discrepancies in certain scores (high score in one area with a low score in another area can indicate a learning disability). It can also mean there was a cultural disadvantage for the person taking the test. IQ Global score determined by comparing to the average score of others in your same general age group rather than by mental age. Average score is fixed for each age group at 100. Average or 2/3 of all scores fall between

Subtests of Wechsler

Testing Spatial Reasoning

Principles of Test Construction

Qualities of Good Tests Standardized—administered to large groups of people under uniform conditions to establish norms that can be compared to Reliable—ability to produce consistent results when administered on repeated occasions under similar conditions Valid—ability to measure what the test is intended to measure

Standardized scores fall on the Normal Curve with the most common scores falling in the middle. 100 = average score

Standardized Scoring of Wechsler Tests To keep the average on the IQ test at 100, tests must be restandardized to account for the… Flynn Effect – the fact that intelligence test performance tends to increase over time. –(A score of 100 in 1920 would only be worth a 76 today!) This more than likely caused by environmental effects: better nutrition, schooling, smaller families, more parental investment

Types of Reliability Test-retest reliability - taking the same test and receiving a similar score Split-half - the score on one half of a test’s questions is similar to the score on the other half Scorer reliability – the score of the test should be similar no matter which scorer is scoring the test

Test Validity The extent to which a test measures or predicts what it is suppose to Does an achievement test accurately measure accomplishments? Content Validity Does an aptitude test accurately predict the person’s future performance? Predictive Validity One needs to know the purpose of the test

What do IQ tests measure about your mind? Mental speed and span of working memory –typically use a digit span test to measure this –more recent studies find significant correlations between reaction times and IQ scores Why is this important? –mental quickness may expand capacity of working memory which aids in problem solving

IQ Tests do a good job measuring: –Logical & Abstract thinking –Problem solving –Capacity to acquire knowledge IQ Tests however do not measure: –Creativity – artistic ability –Achievement motivation –Goal-oriented behavior –Ability to adapt to one’s environment Academic aptitude tests are good predictors of achievement for children ages 6-12 but their predictive values drops the older you get.