Intelligence and Intelligence Quotient Test

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the idea of developing a physiological measure, he ended up with a test he called "aptitude for academic achievement” this test was constructed to be relevant in academic settings. Simple procedures used identified behaviors for each age (important - this test was age specific - also known as the "age-standard method"). This made it possible to establish range of normality ("norms"), then checked to see if the child/person possessed these abilities

a) 3 years: show eyes, nose, mouth, name objects in a picture, repeat figures, repeat a sentence of 6 syllables, give last name

b) 5 years: compare 2 boxes of different weights, copy a square, repeat a sentence of 10 syllables, put together 2 pieces of a game

c) 7 years: indicate omissions in drawings, copy a written sentence, copy a triangle and a diamond, etc.

d) 9 years: give the date complete, name days of the week, give definitions, memory

this measure proved highly successful in predicting school success.

( Psychology Class Notes > Intelligence

http://www.alleydog.com/101notes/intelligence.html#.VyDjSUeI8nZ )

the calculation of this test was very simple. Alfred Binet gave the test to normal children at multiple ages and score were divided to their age

• mental age vs. chronological age

this test was more concentrated on academics. And was not valid for everyone, it was not fair.

Wechsler tests

Wechsler test was developed by scholar David Wechsler. Which is contain several tests like:

Wechsler Adult Intelligence Scale (WAIS)

Wechsler Adult Intelligence Scale for

Children (WISC)

Verbal Subtests and Performance Subtests

Each test was designed for difference ages as you can understand from names. Test’s scale compares a person’s intelligence test scores with those of the mean scores of their age peers. Those who perform exactly the same as their age peers would receive the score of 100. But Several times the test’s scale was changed and normalized to increase accuracy.

WAIS content

• Verbal Subtests

Vocabulary- define words

Similarities- how are an airplane and a car alike

Arithmetic -simple operations

Digit Span -digits in STM capacity

Information -who was Martin Luther King, Jr.?

Comprehension- why are there taxes?

• Performance Subtests (nonverbal)

Picture Completion- what is missing?

Digit-Symbol Coding

Block Design

Matrix Reasoning

Picture Arrangement- order pictures

Analyzing WAIS in perspective of Standardized Test

• standardized sample - random population

• normal distribution

• norming (raw score vs. standardized score)

mean = 100 standard deviation(sd) = 15 for

WAIS

67% of people are +/- 1sd (85-115); more than 2sd = 4.54%

Standardized Test (Intelligence, Introduction to Psychology Brain and Cognitive Sciences MIT Open Courseware lecturer John Gabriel 2011)

Now Intelligence tests are no longer scored by using the Mental Age/ Chronical Age ratio. Instead, IQ is calculated by comparing a one person to the average of other people of the same age.

Average is still 100.

Validity and reliability of IQ test

Validity and reliability is very important for each standardized test in order to test to be Reliable (same score on two occasions) and Valid (measures what it is supposed to measure).

As mentioned before test is depend on age. If someone take the test before 6th birth day and retakes it after he is 6 years old. There will be huge gap. For that reason, we cannot fully say that it is so reliable but still it is one of the best ways to measure.

For validity of IQ test we can say that it is correlated with GPA in school, college and salary income, career success and stability in marriage. And there is 25% of variation caused by personality, culture and education differences.

Theories of Intelligence

Different researchers have proposed a several theories to explain the nature of intelligence. There are some of the major theories of intelligence that have emerged during the last century.

Charles Spearman - General Intelligence

British psychologist Charles Spearman (1863-1945) described a theory he pointed to view as general intelligence or the g factor. After using a way known as factor analysis to test some mental aptitude tests, Spearman realized that scores on these tests were significantly similar. People who performed well on one cognitive test supposed to perform well on other tests while those who scored badly on one test supposed to score badly on others. He concluded that intelligence is general cognitive ability that could be measured and numerically expressed. Spearman divides the tests to g – general intelligence and s – specific intelligence

(Spearman, C. (1904). "General intelligence," objectively determined and measured. American Journal of Psychology 15, 201-293.)

Louis L. Thurstone - Primary Mental Abilities

Psychologist Louis L. Thurstone (1887-1955) offered a differing theory of intelligence. Instead of viewing intelligence as a single, general ability, Thurstone’s theory concentrated on seven different "primary mental abilities." The abilities that he was referring were: Verbal comprehension, Reasoning, Perceptual speed, Numerical ability, Word fluency, Associative memory, Spatial visualization.