Lecture 2 Measurement of Intelligence

Question 1

Wechsler tests (1939)

Answer 1

Wechsler (1939): Wechsler-Bellevue Scale
standardised on 1500 adults

Revised as two tests (1955):
Wechsler Adult Intelligence Scale (WAIS)
Wechsler Intelligence Scale for Children (WISC)

All administered on a one-to-one basis

Widely used today, now the WAIS-IV and WISC-V

Improvement on previous intelligence tests:
Single set of tests: Designed so that people of different ages could take them
The idea of ‘deviation IQ’

Deviation IQ: based on how people score relative to the average scores of other people of the same age
IQ = Test score/Expected score for age X 100

Question 2

Deviation IQ

Answer 2

Two steps to standardised scores:

Determine the expected score for each age

Transform the scores to a standardised form

Wechsler transformed the data for each age band so that IQ is normally distributed, with a mean of 100 and a standard deviation of 15

Question 3

Verbal comprehension index

Answer 3

Vocabulary
What do certain words mean?
chair, hesitant, presumptuous

Similarities
What do two things have in common?
In what way are a lion and a tiger alike?

Information
(general knowledge)
Covering people, places and events
Name three oceans

Comprehension (understanding verbal info)
Everyday life problems
Why do people require driving licences?

Question 4

Working memory index

Answer 4

Arithmetic
(mental arithmetic problems)
If you have 15 apples and give 7 away, how many are left?

Digit span
Repeat digits in exact or reverse order (2 – 9)
3 – 9 – 1 – 7 – 4 – 5

Letter-number sequencing
Repeat numbers then letters, in numeric / alphabetical order
F – 7 – K – 2 – E – 8

Question 5

Perceptual Reasoning Index

Answer 5

Picture completion, block design, matrix reasoning

Question 6

Processing Speed Index

Answer 6

Digit-symbol coding (change symbols to numbers)

Symbol search (search for a symbol)

Question 7

The Wechsler tests for children

Answer 7

Wechsler Intelligence Test for Children (WISC-V)
for children aged 5 - 16 years old

Wechsler Primary and Preschool Scale of Intelligence (WPPI- IV)
for children 2 - 7 years old

Similar tasks to the WAIS. Takes around 1 hour

Full-scale IQ plus 5 index scores:
Verbal Comprehension Index
Visual–Spatial Index
Fluid-Reasoning Index
Working Memory Index
Processing Speed

Question 8

The Stanford-Binet Intelligence Scale

Answer 8

Last week: original developed in 1916 by Lewis Terman

Recent versions can be used with children (age 2+) and adults (up to 85 years old)

Administered one to one with
a psychologist

SB5 (2003) maps onto
CHC theory

Question 9

Raven’s Progressive Matrices

Answer 9

Raven’s matrices are based ‘g’

Test abstract ability
free of culture
free of language influences

Non-verbal problems
Abstract reasoning
Require no knowledge of a particular culture

Question 10

Summary of Raven’s Progressive Matrices

Answer 10

Intelligence assessed by ability to work out the underlying rules

60 items of increasing difficulty (used on all ages)

Overall IQ: deviation from a standardized score

Question 11

Psychometric vs. cognitive approaches to intelligence

Answer 11

WAIS, Stanford-Binet and Raven’s matrices are all examples of Psychometric approaches to intelligence

-Based on the findings of factor analytic studies

-Look at the psychometric properties of intelligence scales

Cognitive approach to intelligence focusses on biological and physiological processes

Question 12

Cognitive and biological measures

Answer 12

Simple biological and physiological factors may be good indicators of intelligence
Advantages:
-quick and easy to administer
-Measures abilities that underlie performance on psychometric tests
brain size and elementary cognitive tasks

Question 13

Brain size

Answer 13

Tiedmann (1836) suggested that there is an “indisputable” link between brain size and mental energy

Magnetic resonance imaging
(MRI) scans have made it possible
to test this hypothesis

McDaniel (2005) Meta analysis of 37 studies: correlation between brain size and IQ to be 0.33

Causation?
Does a large brain cause
high IQ, or does having a
high IQ create a large brain?

Question 14

Cognitive approach to intelligence

Answer 14

Suggests that ‘g’ is supported by multiple cognitive mechanisms

-Working memory
Maintain, update, and manipulate information

-Processing speed
Speed at which cognitive operations can be performed

-Explicit associative learning
Ability to remember associations between stimuli

Question 15

Multiple Cognitive mechanisms

Answer 15

Included in factor-analysis theories of intelligence (e.g., CHC has measures of speed, short term memory, etc.)

All are correlated with ‘g’
people with high ‘general intelligence’ tend to have good working memory, fast processing speed and are good at learning

Question 16

Elementary cognitive tasks (ECTs)

Answer 16

Simple tasks that measure cognitive processes
Understanding and identifying a stimulus
Discrimination tasks
Visual Search tasks
Memory tasks

Assessed using Reaction Times (RT), Standard Deviations in Reaction Times (SDRT) and Inspection Times (IT)

Reaction times on ECTs correlates with IQ test performance (around 0.35)

Jensen (1998) ECTs are more accurate and analytical than IQ tests - not dependent on past learning

Question 17

What makes a good IQ test?

Answer 17

Sattler (2002): three main qualities that good intelligence tests have in common
A variety of tasks
Standardisation of administration
Norm referencing

Also need good reliability (consistent results) and validity (they measure what they say they measure)

Question 18

Variety of tasks

Answer 18

To assess a full range of abilities: need a number of different tasks e.g., 12 subtests on the WAIS, 10 subtests on SB5

Provides fuller understanding of overall intelligence
Also highlights strengths and weaknesses

Question 19

Standardisation of administration

Answer 19

Important to have control over the intelligence test environment

Setting: Comfortable setting, no distractions e.g. noise in the testing room, number of people present

Administration: Instructions, Wording of questions, consistency in the time taken to complete the test, supervised by a qualified administrator

Question 20

Norm referencing

Answer 20

A good intelligence test needs to have ‘norms’

Based on the average score for people in each age group – large numbers needed

It is then possible to compare an individual’s intelligence score with the expected score on the test for a particular age group

Question 21

Reliability and validity

Answer 21

Reliability: Does the test consistently measure intelligence?

Validity: Does the test measure intelligence?

Question 22

Reliability

Answer 22

There are two types of reliability we are interested in when considering intelligence tests:

Internal reliability – positive correlation between items on test – assesses whether they are measuring the same construct

Test-retest reliability – a good intelligence test will show good reliability across time

Question 23

Internal reliability

Answer 23

Developers of standardised intelligence tests focus on ensuring high internal reliability
i.e., they remove items that do not positively correlate with other items

On tests such as the WAIS and Stanford-Binet, internal reliability is likely to be high

Question 24

Reliability over time

Answer 24

Short-term IQ test fluctuation: up to 15 IQ points (Benson, 2003)

BUT: longitudinal studies suggest that IQ is reasonably stable over long-term
-Berkeley growth study – longitudinal study looking at people in Berkeley born between 1928 and 1929
-Children tested yearly on a number of intelligence tests
-IQ scores at 18 years of age positively correlated with those at 12 years (0.89) and 6 years (0.77)

Question 25

Reliability over time

Answer 25

Similarly, Deary et al. (2000) found a strong correlation between IQ at 11 and 77 years old (r = 0.73)

Question 26

Validity of intelligence tests

Answer 26

Validity = does the test measure what it claims to measure?
Do intelligence tests measure intelligence?

Three types of validity:
-face validity
-concurrent validity
-predictive validity

Question 27

Face validity

Answer 27

‘On the face of it’, does the intelligence test appear to measure what it sets out to measure?

IQ tests undergo substantial development work
- an item that requires mental
arithmetic probably does measure
mental arithmetic ability

Question 28

Concurrent validity

Answer 28

Refers to the relationship the intelligence test has to other intelligence tests

A good intelligence test should correlate well with other intelligence tests

Question 29

Predictive validity

Answer 29

Predictive validity refers to whether the test can predict future performance

A good intelligence test has to be able to predict future performance

Question 30

Do intelligence tests measure intelligence?

Answer 30

Tend to have all three types of validity

But depends on the definition of intelligence used by the test developers

Benson (2003) Many tests based on ‘g’, but still debate over whether ‘g’ exists

Question 31

Boring (1923)

Answer 31

“Intelligence as a measurable capacity must at the start, be defined as the capacity to do well in an intelligence test. Intelligence is what the tests test”

Question 32

Gardner’s multiple intelligences evaluation

Answer 32

But… very time consuming to evaluate all of them

Little research on validity and reliability

Question 33

Salovey & Mayer’s (1990) model

Answer 33

Four-branch model
perceiving, facilitating, understanding, managing

Mayer-Salovey-Caruso Emotional Intelligence Test version 2, (MSCEIT2),

141-item scale, produces an overall score of emotional intelligence plus subscale scores

Perceiving: ability to identify emotion

Facilitation: Ability to use emotion
What mood(s) might be helpful to feel when meeting in-laws for the first time?

Understanding: ability to understand emotion

Managing: ability to manage emotions

Question 34

Goleman’s theory of emotional intelligence

Answer 34

Measured using the Emotional Competence Inventory (Goleman and Boyatzis, 2005)
designed for use in the workplace

360° instrument – other people evaluate individuals on their emotional intelligence

e.g., the assessor determines whether the person:
respects, treats with courtesy and relates well to people of diverse backgrounds
accurately reads people’s moods, feelings or non-verbal cues

Question 35

Emotional-social intelligence model

Answer 35

Emotional Quotient Inventory (EQ-i; Bar-On, 1997)
First measure of emotional intelligence
Scores can be converted into standard scores, mean of 100 and s.d. of 15

133 items, e.g., “I’m in touch with my emotions”

Five-point response scale
very seldom or not true of me (1) to
very often true of me or true of me (5)

Question 36

Tests of emotional intelligence evaluation

Answer 36

No objective measure for validity of emotional intelligence tests

Less research, so less information on reliability and validity

What else is missing?

What else contributes to the ability to perform tasks?

What else affects success and achievement?

Question 37

Summary

Answer 37

Typically, IQ tests measure a specific type of problem-solving, verbal, mathematical ability
This ignores many other traits that could be considered ‘intelligent’
Practical difficulties in measuring multiple intelligences
Emotional intelligence scales do exist but are difficult to validate
Several other things could be considered (e.g., creativity)