Intelligence Flashcards
What did Prof Sir Godfrey Thomson do?
Obtained only record of IQ-type scores from full national year-of-birth cohorts (Scotland 1932 & 1947)
By 1948 - 1.25 million Moray House Tests were sold
Advocate of universal education - saw his mental ability tests as useful means to give poor children a chance in life by looking past pupils’ social status
What did Prof Ian Deary unearth?
The Scottish Mental Surveys Test in 1997
How many 11 y/o children were tested in the original Scottish Mental Surveys?
1932 - 87, 498
1947 - 70,805
What research did Ian Deary carry out?
He gathered 1641 people from the two original cohorts and retested them on the mental ability test at around 80 years old
What did the retesting of Scottish Mental Survey investigate?
- How thinking skills change as we age
- How to maintain a healthy brain throughout life (cognitive functions ageing well) - examining health, lifestyles, genetics etc
- How did intelligence scores at 11 relate to later life outcomes
What is a fundamental purpose of intelligence assessment?
Prediction
What is the main definition of intelligence? (Gottfredson, 1997)
Intelligence is a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broader and deeper capability for comprehending our surroundings - ‘catching on’, ‘making sense’ of things, or ‘figuring out’ what to do.
Is intelligence a general or specific mental ability?
General
What are two common themes in definitions of intelligence? (experience and environment)
Capacity to learn from experience
Capacity to adapt to environment
Why is it difficult to understand how the brain processes complex cognitive constructs?
Because the brain is not likely to adhere to the boundaries imposed by our inherited terms (provided by people who knew nothing about brain activity).
What is boxology and why is it a problem in psychology?
- Psychologists love boxing off areas of the brain
- PFC - everything complex is claimed to happen here
- Connections between areas are also crucial
What is a hypothetical construct and operationalisation?
A hypothetical construct is an explanatory variable which is not directly observable
Operationalisation is making a concept clearly distinguishable and measurable, to understand it in terms of empirical observations
What are examples of operationalising hypothetical constructs?
Intelligence - e.g. Number of questions on IQ test
Aggression - e.g. Number of verbal attacks in a conversation
Overconfidence - e.g. Perceived vs ACTUAL performance
What are implicit theories of intelligence?
Data comes from asking people their notion of intelligence
Constructs in a person’s mind
Used for formulating cross-cultural views about intelligence
Can help understand or provide basis for explicit theories
Drive the way ppl. evaluate their own & other ppl.’s intelligence
What are explicit theories of intelligence?
Conducted by scientists
Based on data collected
Performance on tasks presumed to measure intelligence
Constructs – could be factors, components, schemata
Been tricky to agree on operational definition of intelligence
How did Sternberg (1981) investigate individual conceptions of intelligence in groups of laypersons? (Participants)
People studying in a college library
People entering a supermarket
People waiting for a train in a railway station
How did Sternberg (1981) investigate individual conceptions of intelligence in groups of laypersons? (Method)
Phase 1: People were asked to list behaviour that were characteristic of
- Intelligence
- Academic intelligence
- Everyday intelligence
- Unintelligence
Phase 2: Other people were asked to rate how well each of behaviours listed reflected aspects of intelligence.
What did Sternberg find were the three dimensions of intelligence in laypersons?
Practical problem solving ability
Verbal ability
Social competence
What is practical problem solving ability? (laypersons ideas of intelligence)
Ability to be practical and logical with regard to daily problems in various situations and relationships, especially when one cannot see a way out.
What is verbal ability? (laypersons ideas of intelligence)
Ability to express yourself and converse with others confidently and with some eloquence.
What is social competence? (laypersons ideas of intelligence)
Skills necessary to be accepted and fulfilled socially. High levels of knowledge, understanding, competency, motivation and confidence in terms of themselves and others.
What were experts’ three dimensions of intelligence? (Sternberg, 1981)
Verbal intelligence
Problem solving ability
Practical intelligence
How did experts’ and laypersons’ dimensions of intelligence differ?
Both agreed on problem solving and verbal abilities
Practical intelligence in experts, but social competence in laypersons
However they did agree on this somewhat
What are laypersons’ implicit conceptions of an intelligent person in Western culture?
Emphasis on the speed of mental processing and the ability to gather, assimilate and sort quickly and efficiently.
Intelligent person:
- Can see answers to problems quickly and then act on them
- Comes up with the solution first
- Articulates these ideas verbally, clearly, fluently and in a precise manner
What are laypersons’ implicit conceptions of an intelligent person in Eastern (non-Western) culture?
Good cognitive skills, good memory but also social, historical and spiritual aspects of everyday interaction.
Problem solving skills include not only the individual but also considers
(a) family and friends (seeking advice)
(b) knowledge of history (knowing how people have approached this problem in the past)
(c) own spiritual needs (consequences for the human soul)
How has Korea’s cultural definition of intelligence changed?
Unintended effect of reshaping cultural definitions introduced by Western IQ tests in Korea.
How did US adults describe ideal intelligent persons at 6 months? (Siegler and Richards, 1982)
(Ideal intelligent baby):
- Able to recognize people and objects
- Shows signs of motor coordination
- Shows levels of awareness
- Makes some verbalisations
How did US adults describe ideal intelligent persons at 2 years? (Siegler and Richards, 1982)
Verbal abilities
Evidence of an ability to learn
Awareness of people and environment
Motor coordination
Curiosity
How was average intelligence in all age groups defined? (Berg and Sternberg, 1982)
(a) ability to deal with novelty
(b) everyday competence
(c) verbal competence
How was ability to deal with novelty and everyday competence related to age for exceptional intelligence? (Berg and Sternberg, 1992)
Ability to deal with novelty was emphasised as important for a hypothetical young adult (30 years)
Everyday competence was emphasised as important for a hypothetical older adult (70 years).
How did Arts professors see an ideal intelligent person? (Sternberg, 1985)
Knowledge
Ability to use knowledge
To weigh up possible alternatives
To see analogies
How did Philosophy professors see an ideal intelligent person? (Sternberg, 1985)
Critical and logical abilities
Ability to follow complex arguments
To find errors in arguments and generate new arguments
How did Physics professors see an ideal intelligent person? (Sternberg, 1985)
Precise mathematical thinking
Ability to relate physical phenomena to the concepts of physics
To grasp the laws of nature quickly
How did Buisness professors see an ideal intelligent person? (Sternberg, 1985)
Ability to think logically
To focus on essential aspects of a problem
To follow others’ arguments and see where they lead
What is Savant syndrome?
Special ability usually accompanied by prodigious memory
Approx. 1 in 10 persons with autistic disorder show some savant skills - Treffert (2009)
What are examples of people with Savant syndrome?
Nadia Chomyn - struggled to talk but had exceptional drawing skills at 5 years old
Brittany Maier - was mute but started to sing beautifully and could memorise songs very quickly
Kim Peek - could memorise thousands of facts, read one page with left eye and one page with right eye, but could not dress himself and struggled socially
Are specific savant abilites considered evidence of high intelligence?
Usually no
Extraordinary but narrow mental ability is not what is usually considered evidence of high intelligence by many researchers
However, savant research raises questions on the existence of multiple intelligences in the areas where savants appear, e.g. music, mathematics, art, mnemonics etc., even in the face of low IQ scores
What are specific intelligences and general intelligence?
Specific - verbal, mechanical, spatial, maths
General intelligence (g) - combination
What does doing well on one mental ability predict?
People tend to do well on everything else
What does IQ measure?
Test score based on subset of mental abilities for everyday intelligence - good predictor of intelligence
What is the g factor?
A statistical result
Used to refer to:
general intelligence
general cognitive ability
general mental ability
Some posit g-factor is more biological / genetic
e.g. Haier (2022)
What is the intelligence quotient or IQ?
Single score representing range of mental abilities
Can be influenced by social & cultural factors, for example
Large sample of IQ scores are normally distributed
What is the normal distribution of IQ scores?
The bell curve
What is the mean IQ score and what are the standard deviations?
Mean = 100
SD = 15
What is the average IQ range? What percent of people have this?
Between 85 - 115
68% of people
What percentages of people are in each SD of IQ score?
40-55 = 0.1%
55-70 = 2%
70-85 = 14%
85-100 = 34%
100-115 = 34%
115-130 = 14%
130-145 = 2%
145-160 = 0.1%
Which branches of psychology did Sir Francis Galton find?
Differential psychology
Experimental psychology (together with Wundt)
What did Galton conceive intelligence to be? What was his interest within this?
Intelligence = dealing with information gained through the senses (‘idiotic’ people are unable to distinguish colours, heat and cold, etc.)
Galton’s interest: showing that individuals differ in intelligence
What was Galton the forefather of?
The intelligence test (response to sensory information, reaction times)
Studied families - hereditary intelligence
What is psychometrics and who founded it? How did he study it?
Measuring differences in mental ability - Galton
“Anthropometric Laboratory”, London 1885
9000 sets of data for different ppl. to obtain representative sample
Galton figured his statistical analyses would only be reliable with large sample
How did James McKeen Cattell measure simple mental processes?
Taking Galton’s view on the importance of the ‘senses’ for intelligence
Began to measure “simple mental processes”
He published a provisional list of 10 ‘mental tests’ designed to measure individual differences
e.g. sensation, weight discrimination, reaction times (whatever tests were at his disposal)
What did Wissler (1901) compare Cattell’s mental test scores to?
Wissler (1901) using new correlation stats perfected by Karl Pearson (from Galton’s ideas) compared Cattell’s ‘mental test’ scores in UG’s with their college grades.
What was the fall of Cattell’s mental tests?
Wissler found no correlation between these tests, and tests did not correlate with college grades (though grades on one course corelated well with grades on others)
What did Galton and Cattell’s research show about what is important when trying to devise and intelligence test?
When trying to devise a test of intelligence, one must have some independent criterion of intelligence with which the test can agree
What did the French government commission Alfred Binet to do?
French government commissioned Binet to design an intelligence test for children to identify students requiring alternative educational provision
Pragmatic approach, relying more on practicality, common sense, coping with the day-to-day world
What was Binet’s intelligence test? (1905)
1905 Binet created the first intelligence test (for children)
The Binet-Simon scale included 30 short everyday-related tasks:
Following a light match with your eyes
Naming parts of the body
Counting coins
Naming objects in a picture
Recalling a number of digits after being shown a long list
Word definitions
Filling in missing words in a sentence
What did the Binet-Simon scale use children’s age as?
An independent criterion of intellectual competence
e.g. 4 year olds can copy a square but not a diamond - build up characterisation for each population to create a figure of normal intelligence
Final set of tests (Binet & Simon 1911) from 3 – 10 years of age
What does it mean to say that Binet used a relative or normative measure of intelligence?
A mental age of 6 was the average score obtained by lots of 6-year-olds
A 5-year-old with a mental age of 6 was advanced, but a 10-year-old with a mental age of 6 was behind
What did the Binet scales form the basis of? Binet’s lasting contribution?
The Binet Scales formed the basis for modern IQ tests, just as mental age formed the basis for IQ scores
The use of age in psychological testing is one of Binet‘s lasting contributions
What term did William Stern coin?
Coined the term intelligence quotient (IQ)
What is IQ score a measure of? (Stern)
To see if child is developing normally – examine the ratio of child’s mental age to physical age
IQ Score:
(Mental age ÷ Physical age) x 100
Mental age is averaged across all subtests, (x 100) avoids dealing with fractions
If John is 10 years old, and his test score is the same as an average 8 year old, what is his IQ score?
80
What is a problem with measuring mental age?
Hard to assess after age 16
If two people of different ages have the same IQ score, are they equally intelligent?
No
They both score above average relative to their peers of the same age
IQ scores are only meaningful relative to people of same age
What does it mean to say IQ is an ordinal measure?
IQ scores are not absolute measures, like centimetres of height or kilometres of distance
IQ is an ordinal measure where we are simply rank-ordering people
There is no zero for IQ, as there is for height or distance
Someone with an IQ of 120 is not twice as intelligent as another with an IQ of 60
To say that someone has an IQ of 130 is to say their score lies in the top 2.5% of a representative sample of people of the same age
What is the Stanford-Binet test? (Terman, 1916)
1916: Lewis Terman produced a Stanford revision of the Binet-Simon scale:
the Stanford-Binet test (now on 5th edition) still remains one of the standard tests of intelligence to this day
Virtually a new test for Binet’s with forty new items added with far more children tested in each age group
What was a problem with the Stanford-Binet test? (1916)
These tests with trained examiners were clunky to administer and certain answers open to interpretation
Who designed an IQ test for the US army and what was this like?
Yerkes with the help of Terman and Goddard designed a new IQ test for use by US army
2 tests - alpha and beta
Questions were timed and multiple-choice style
Beta test designed for illiterate groups
Simple tasks as quickly as possible
What was the impact of Yerkes army IQ tests?
The army tests transformed public opinion to mental tests
Yerkes published a new Intelligence Test in 1919
Tests were used everywhere (schools, universities, business firms, clinical settings)
1.75M were tested – huge sample
What is the logic behind generating an operational definition?
e.g. measuring aggression in children - instead of following them around for a week and counting the number of shoving behaviours, better solution might be to develop a set of questions or tasks highly correlated with shoving:
- Do you think most people need a good punch in the face from time to time?
- How quickly can you decapitate this doll?
Hypothetical property of anger leads to a consequential behaviour of shoving which correlates with response to answers to questions or performance on task
e.g. Hypothetical property of intelligence, consequential behaviour of job performance, response to IQ test (performance)
What are advantages of using a test over measuring consequential behaviour?
Measuring consequential behaviour is usually not very efficient
Using a test has several advantages:
Easy to do
Less time consuming
Larger samples
Standardised
What happened to IQ tests in the 20s and 30s?
Exapnded - Especially in US – great expansion in IQ tests – lots of rival tests
What did Buros publish?
Buros started publishing a yearbook, listing all mental tests, e.g. 1978 edition included 100 intelligence / mental tests
What are the Weschler tests? (David Weschler)
1939 Wechsler-Bellevue Scale. Revised in 1955 Wechsler Adult Intelligence Scale
Taken over the Stanford-Binet test as the most widely used IQ test today
What are the two versions of the Weschler tests?
Wechsler Adult Intelligence Scale (WAIS) – latest edition (IV) standardised among 2200 adults (16-90 years)
Wechsler Intelligence Scale for Children (WISC) – for children (5-16 years)
Why did Weschler create his tests to build on Stanford-Binet test?
Created to profile his patients in the clinic
Wechsler was sceptical that the Stanford-Binet relied heavily on verbal ability and only used a single score
His test tapped into range of cognitive abilities (reflecting his believe there were many aspects to intelligence) - wanted to capture multiple intelligences
Current version WAIS-IV released in 2008 with fifth edition set for release in 2024
WAIS-R Subtests to measure several different aspects of intelligence (including 6 verbal and 5 performance tests)
15 varied tests given to 1800 adults found people who were good at one of the 15 tests tended to be good at the other 14
How are verbal and performance IQ obtained in WAIS-R tests?
Verbal - information, comprehension, arithmetic, digit span, similarities, vocabulary
Performance - picture arrangement, picture completion, block design, object assembly, symbol search (perceptual speed)
What four types of intelligence does the Weschler Adult Intelligence Scale IV measure?
Verbal comprehension
Perceptual reasoning
Working memory
Processing speed
What does the WAIS-IV contain and how is it obtained and administered?
15 different mental tests (wide range of mental effort)
Many hundreds of pounds to buy
Can only be bought by certified people, e.g. educational, clinical, occupational psychologists
Administered by trained psychological tester working one to one for up to 2 hours
Like a clinical performance interview of the patient for two hours
Which 15 subtests is the WAIS-IV comprised of?
Similarities
Vocabulary
Information
Comprehension
Block design
Matrix reasoning
Visual puzzles
Figure weights
Picture completion
Digit span
Arithmetic
Letter-number sequencing
Symbol search
Coding
Cancellation
How are similarities measured? (WAIS-IV)
Say what two words have in common. For example: In what way are an apple and a pear alike? In what way are a painting and a symphony alike? How are whales and lions similar? (18 questions)
How is vocabulary measured? (WAIS-IV)
Tell the tester what certain words mean. For example: chair (easy), hesitant (medium), presumptuous (hard). (30 words)
How is information measured? (WAIS-IV)
General knowledge questions covering people, places, and events. For example: How many days are in a week? What is the capital of France? Name three oceans. Who wrote The Iliad? What imaginary line divides the planet earth into north and south hemisphere?
(26 questions)
How is comprehension measured? (WAIS-IV)
Answer questions about everyday-life problems, aspects of society, and proverbs. For example: Tell me some reasons why we put food in a refrigerator. Why do people require driving licences? What does it mean to say ‘a bird in the hand is worth two in the bush’? (18 questions)
How is block design measured? (WAIS-IV)
While looking at a two-dimensional pattern made up of red and white squares and triangles, try to reproduce the pattern using cubes with red and white faces, and faces that are diagonally half-red and half-white.
(14 patterns)
How is matrix reasoning measured? (WAIS-IV)
Find the missing element in a pattern that is built up in a logical manner. (26 questions)
How are visual puzzles measured? (WAIS-IV)
There is a shape at the top of each page. Below it are six part-shapes. Find the three part-shapes that can be put together to make the shape at the top of the page.
(26 questions)
How are figure weights measured? (WAIS-IV)
Choose the correct objects to balance a scale in weight. (27 questions)
How is picture completion measured? (WAIS-IV)
Spot the missing element in a series of colour drawings. For example: that spokes are missing from one wheel in a picture of a bicycle; that one buttonhole is missing from a jacket in a picture of a person. As in the earlier tests in the collection, the questions become progressively more difficult. (24 drawings)
How is digit span measured? (WAIS-IV)
Repeat a sequence of numbers to the examiner. Sequences run from 2 to 9 numbers in length. An easy example is to repeat 3–7–4; harder is
3–9–1–7–4–5–3–9. In the second part of this test the sequences must be repeated in reverse order, e.g. 24-3-7-12 backwards is 12-7-3-24
(Maximum of 16 forward and 16 reversed sequences)
How is arithmetic measured? (WAIS-IV)
Solve mental arithmetic problems. These involve simple counting, addition, subtraction, multiplication, division, and percentages.
(22 questions)
How is letter-number sequencing measured? (WAIS-IV)
The examiner reads a list (as short as two, or as long as eight) of alternate letters and numbers. The person being tested must repeat them, putting the numbers first and in numerical order, followed by the letters in alphabetical order. (Maximum of 30 trials)
How is symbol search measured? (WAIS-IV)
Identify, from a list of abstract symbols, which symbol in a given pair of target symbols is contained in the list. Assesses information processing speed and visual perception.
(As many as can be completed correctly in two minutes)
How is coding measured? (WAIS-IV)
Write down the symbol that corresponds to a given number.
(As many as can be completed correctly in two minutes)
How is cancellation measured? (WAIS-IV)
In a large sheet of paper with pink triangles and squares and blue triangles and squares, put a pencil line through each blue square and each pink triangle. There is a second sheet with red or yellow stars and circles. (The time to finish each sheet is taken)
What mental function does the WAIS-IV test?
Seeing similarities and differences
Working out and applying rules
Drawing inferences
Working out how to construct shapes
Working with numbers, attending to details
Explaining practical actions in everyday life
Recalling general knowledge
Articulating the meaning of words
Processing simple information at speed
Remembering and manipulating mental material
What is the average correlation between all mental ability test scores on the WAIS-IV?
0.45
Highest = 0.74 (vocab and comprehensions)
Lowest = 0.21
All positive correlations
Which cognitive domains did correlations cluster into on the WAIS-IV?
Verbal comprehension (0.7)
Perceptual reasoning (0.52)
Working memory (0.62)
Processing speed (0.51)
What is the three level hierarchy of mental ability test scores on WAIS-IV?
Level 1 = individual cognitive tests
Level 2 = cognitive domains
Level 3 = g
Who were the Weschler intelligence tests designed for?
Assess intelligence for all people and all ages
What is deviation IQ? (Weschler)
Wechsler carefully stratified by age as well as by other standard demographic characteristics (sex, social class, region of the country), so an IQ score on WAIS is simply a reflection of an individual’s relative standing with respect to others within the same cohort
What is the WAIS IQ formula?
(Actual test score ÷ expected test score for that age) × 100
> All ranges for intelligence scores for all ages were transformed so they had a middle score of 100
What are Raven’s progressive matrices?
Standard Progressive Matrices first published 1938
Non-verbal approach. Identify missing elements in pattern (in the form of matrices)
Paper and pencil, multiple choice test (large groups can be tested at same time). 60 items increasing in difficulty in each of the 5 blocks
What are advantages of Raven’s progressive matrices over other IQ tests?
Freer of cultural, language differences, and better for deaf (minimum of instructions)
What abilities do Raven’s progressive matrices measure?
Focussed on one class of test believed to measure abstract reasoning and nothing else. Very different from Wechsler tests.
Eductive ability (Latin “educere” meaning to “to draw out”) – think clearly, make sense of complexity
Reproductive ability – to store and reproduce ability
Figuring out the underlying rules that explain the progression of shapes
What are correlations like between WAIS and Raven’s progressive matrices?
Very different from WAIS – yet still the correlations between WAIS and Raven’s between 0.40 and 0.75 (Burke, 1958, 1985; Court and Raven, 1995)
What is the hierarchy of mental abilities, intelligence, IQ, g?
Mental abilities encompass
Intelligence which encompasses
IQ which encompasses
g
Does IQ really measure intelligence?
It is predictive of intelligence, but just a score
What is factor analysis?
Task of factor analysis is to group variables that are most related, or correlated
Measure the hidden/latent variable by grouped observed variables
More complex method of defining an operational definition – not using a single variable (but several) to define the unobservable factor, e.g. g-factor or general cognitive ability
What is psychometrics?
Measure / quantify psychological phenomenon
Trying to use measurable items to capture unseen psychological process:
- Behavioural observations
- Questionnaires
- Patient assessment
- Test scores
How can constructs like depression or intelligence be measured? (items)
To measure constructs like depression or intelligence - need to find items that relate closely to these constructs (validity)
Items need to be consistent across samples and time
If items reliably measuring the same process, e.g. depression or intelligence, they should all be related to each other
Because we often want to create a single score for each person and trust that score is measuring e.g. high depression
g factor as driving unobserved test results
50% of variance in intelligence worldwide is attributed to g factor
What are communalities?
How much variance in the construct is explained by the group of factors
What is a rotated component matrix?
Gives us the loadings of the factors (row) on the variables (column) – this rotation clusters the variables so that certain variables load as high as possible (and other variables load as low as possible) on each factor
What did Spearman find out about school subject ability?
1904 Spearman observed children’s performance ratings, across seemingly unrelated subjects, were positively correlated
Is the g factor common to all mental tests?
Yes
What did Spearman’s 1904 seminal paper on factor analysis of intelligence find?
Followed pioneering work by Galton using correlations
Developed the earliest version of factor analysis
Coined the term g or the g-factor
Developed his 2-factor theory of intelligence
What is Spearman’s two factor theory of intelligence?
‘Under certain conditions the score of a person at a mental test can be divided into two factors, one of which is always the same in all tests (g factor), whereas the other varies from one test to another (specific factor)
What are specific intelligences examples? Spearman
Verbal
Mechanical
Spatial
Math
What is g and what does it determine?
Underlying all the positive correlations. g is the intelligence required for performance of intelligence tests of all types.
The mental energy/ cognitive horsepower that underlies specific factors of intelligence.
A person’s mathematical ability is not only affected by one‘s specific ability to perform a mathematical task but is also largely determined by that person‘s general intelligence
What did Cattell say general intelligence (g) could be subdivided into?
Fluid and crystallized intelligence
What is fluid intelligence? (Cattell)
Primary reasoning ability
Abstract
Not cultural
Better tested by Raven’s matrices
e.g. inductive reasoning in abstract sequences
Fluid intelligence refers to reasoning and novel problem-solving ability - strongly associated with working memory
What is crystallized intelligence? (Cattell)
Acquired knowledge/skills
Related to cultural/historical background of individuals
Better tested by Weschler scales
e.g. vocabulary, social rules
Crystallized intelligence refers to overlearned skills and static knowledge such as vocabulary and factual knowledge
It is generally related to a person’s stored information and to their cultural influences…Crystallised intelligence (for example knowledge) is intelligence that increases throughout life and is a reflection of one’s cumulative learning experience
What is g? (Spearman and psychometric approach)
Single process of general intelligence (g) which permeates all intellectual activities
g is a mathematical construct = level of correlations between cognitive tasks
What is our reminiscing ability?
To take knowledge that might be adaptive to help us survive and store it for later use
What is the barrier between physiology and psychology?
Average human brain has about 86 billion neurons
Each neuron can be connected to up to 10,000 other neurons
Estimates of between 100 and 1,000 trillion synapses!!!
How can we begin to understand how this complex network gives rise to complex psychological phenomena?
What were Skinner’s behaviourist beliefs?
Breaking down psychology to its simplest elements
Stimulus-response associations
Brain is a sealed black box that you can’t look inside
Input stimulus and output stimulus (some kind of observable behaviour)
Indifferent to what went on in the brain - just theoretical
What are signs of higher intelligence in brain physiology?
Brain cell size to detect oscillations, myelin, higher IQ = longer and more complex dendrites
Is g only present in the frontal lobes?
No - brain wide process
What does the psychometric approach to intelligence do and explain?
Based on the findings of factor-analytic studies that have looked at the various psychometric properties of intelligence scales.
Describes how people tend to differ but it cannot explain why.
Focused on whether people answer items correctly
What is the cognitive approach to intelligence?
The cognitive approach is based on another set of intelligence tests that highlight biological and physiological processes involved in intelligence (lab based).
Focused on how people answer the items, and why some people are better than others at various mental abilities.
Underlying cognitive information-processing
Like a computer - efficiency of problem-solving will be partly dependent on the limits of memory storage and speed of processing.
What are elementary cognitive tasks?
Elementary cognitive tasks (ECTs) are simple tasks to measure cognitive processes, such as understanding stimulus, stimulus discrimination, visual search, retrieval of information / perceptual speed, etc.
- How well a person can manipulate information in the abstract rather than influences by prior knowledge
- Measuring ‘simple decisions’ (small number of mental processes)
- IQ could be broken down into these building blocks
How do elementary cognitive tasks measure response time?
- Median reaction time (average response time over a number of trials)
- Standard deviation of reaction time (RTSD) (individual variability in response time over a number of trials)
- Inspection time (IT) / Evoked potential (EP) – the time people take to process (visual or auditory) information.
What amount of delay between stimulus and response is thought to represent higher intelligence?
A shorter delay
However - Variability of reaction time more crucial than average reaction time
What is the correlation between ECTs and intelligence?
With traditional measures of intelligence, correlations average at about r = .35
Overall scores based on the use of various ECTs with different measures of response times are found to correlate with scores on general intelligence tests of between r = .50 and r = .70
Do ECTs involve past learned information?
No - this makes them useful
What is the Hick reaction time task? (Cognitive approach)
Common procedure in psychometric testing
Measuring people’s choice reaction times with various numbers of choices
- Slope indicates efficiency of a person’s mental processing
- Hypothesis: high psychometric intelligence = flatter slope….however
- Being steady is important! Higher IQ scores = less variable response times
- Conclusion: simple cognitive processes underpin complex thinking
Quick reaction time as task gets more complex - less steep slope - higher intelligence
Higher IQ’s = less variability
Is working memory a measure of g?
Working memory is basic to intelligence differences (Miyake et al., 2001)
General fluid intelligence and working memory both reflect the ability to keep a representation active, particularly in the face of interference and distraction (Kyllonen & Christal, 1990)
What is the N back task?
A typical measurement of working memory
List of letters, have to remember a certain amount of letters previous
What are correlations between working memory tasks and psychometric intelligence?
High correlations between working memory tasks and psychometric intelligence
Tests of working memory are very similar in format and content to standard psychometric tests
What was working memory’s correlation with g? (Colom et al, 2004)
0.96
How did Thurstone challenge Spearman’s unitary g factor?
1938: Thurstone applied a different statistical method – involved weighing the observed variables (e.g. scores on different ability subtests) differently
This yielded not one but a set of “primary mental abilities”
Most tests were positively correlated BUT scores on verbal tests were more highly correlated with other scores on other verbal tests than with scores on spatial tests
Verbal and verbal correlate, spatial and spatial correlate
What does individuals having strengths and relative weaknesses in some cognitive domains suggest about g?
This might suggest that there is no such thing as “g”
- Clusters of correlations suggest primary mental abilities.
(Not specific abilities)
What were Thurstone’s 7 primary mental abilities?
Word fluency
Verbal comprehension
Numerical ability
Spatial visualisation
Perceptual speed
Memory
Inductive reasoning
What was Thurstone’s view of g? How does his own evidence contradict this?
Thurstone de-emphasised ‘g’ and suggested instead that there were a number of stable and independent mental abilities, which were not general like g – e.g. a person might have weak verbal ability and strong numerical ability.
He suggested each person possesses different levels of these seven factors, and these levels do not depend on one another (however the seven were positively correlated even in his own dataset!!)
What is domain general and domain specific intelligence?
g is domain general and primary mental abilities are domain specific
What is emergence of mid-level abilities? (Thurstone)
Using scissors and juggling abilities are highly correlated and have the mid level ability of physical co-ordination
Same with essay writing and time management - academic skill
What was John Carroll’s book (1993)
John Carroll book (1993) 800 pages long! – mammoth task of reanalysing over 400 sets of reliable data on human mental ability testing
130,000 healthy adults, school children, infants, university students, people with learning disabilities and people with mental and physical illness
His analysis was summarised in a diagram he called the ‘three stratum model’ of human cognitive ability
What did John Carroll’s book say about Spearman Thurstone debate?
They were both kind of right
What is Carroll’s three stratum model of human cognitive ability?
g = stratum 3
Cognitive domain (e.g. fluid or crystallised intelligence) = stratum 2
Cognitive task (several narrower abilities from each domain) = stratum 1
Why do people do well on intelligence tests? (Carroll)
They are good overall (have high general intelligence)
They are good at that sort of test (high ability for that cognitive domain)
They are good at that specific test (high ability for specific cognitive task)
Chance favoured them on that particular testing day
Criticises Spearman’s idea of g as genetic and relatively unchanging
Is universal positive correlations among mental tests, i.e. Spearman’s g, a much-replicated empirical finding?
Cross-culturally?
Yes:
Warne and Burningham (2019)
31 non-western nations
97 samples with 52,340 people tested almost all of them showed a general cognitive factor
g accounted for 46% of variance (same as western samples)
What are the three main applications of intelligence tests?
Education
Workplace
Health
How were intelligence tests used for schooling in 1944?
1944: In UK, intelligence tests widely used to select children at 11+ years into an educational ‘strand’ (academic, technical or functional)
Idea was that skills were more important than a pupil’s financial resources and that different skills required different schooling
Results of the tests used to match children’s abilities to their schools
What was the 11+ and why did this become a problem?
Intention was for the 11+ to be like an IQ test consisting of 3 papers: Arithmetic, Writing, General Problem Solving (sometimes with an added Verbal paper). Most tests multiple choice (40-60 minutes long)
The reality was that the required specialist schools were not available at the scale required so the 11+ came to be a fierce competition for places at desirable grammar schools
The passing or failing took on extra emphasis and become resented by many (was phased out by most of UK by 1976)
What are CAT tests used for?
Used for estimating student progress within the context of how well a school is performing
Is the CAT test at 11 a good predictor of GCSE results? (Deary et al, 2007)
74,403 children (37,509 girls, 36,894 boys)
973 secondary schools across 103 LEAs (1/5 of total national dataset)
CAT test scores 1997 vs GCSEs 2002
Correlation of 0.81
However, no difference in CAT scores at 11 but huge sex differences in GCSE’s at 16
What sex differences are there in GCSE results? (Deary et al, 2007)
There were significant sex differences (p<0.001) in virtually all GCSE scores
Girls performed better in every topic except Physics. The effect sizes of the sex differences were often substantial (Art & Design had a Cohen’s d of 0.61!!)
Girls and boys did not differ in g but girls scored higher on residual verbal factor
Are GCSE’s a good predictor of life chances and wellbeing?
Yes
What is the aim of intelligence tests in the workplace?
- Companies use a lot of money in recruiting - especially if they recruit the wrong person
- Issues with work trials - could be not used to the role yet, could find out the role is not for them
- Main issue - very expensive to conduct - not very logistically possible
- Intelligence tests are a lot cheaper and easier
- Gold standard - cognitive ability and psychometric test, supplement with work placements and other tests if you can
What did Schmidt and Hunter (1998) find were good and bad predictors of job competence?
Psychometric intelligence test = good
Age and job experience = bad
What criticisms are there of the psychometric view of cognitive ability playing a big role in occupational sorting?
Much criticism of this view based on lack of representative samples (lots of military data and adult UK and US data) and poor quality data
What is the link between IQ and occupation?
Higher IQ for higher ranking occupations and vice versa
Difference between the highest and lowest mean intelligence estimates amounts to almost two standard deviations
(physical scientists, with 114 vs. packers, bottlers, canners and fillers,
with 87)
Do people with lower IQ scores have poorer life outcomes?
Yes
How similar are intelligence scores between 11 and 77 years?
Prof Sir Godfrey Thomson and cohort of Moray house tests (Scottish mental surveys test)
Ian Deary
On average people did better at 77 than they did at age 11
11 vs 77 scores = 0.63 (large correlation)
This lifetime-long intelligence association been replicated lots with larger samples (correlation ~0.70)
As sample increased - correlation got higher
However there were outliers
Why does some people’s intelligence age better than others? Risks (Brenda Plasman)
Systematic review – found 150ish studies looking for risks or protections against cognitive decline
Found some evidence of risks:
> APOE gene = higher cognitive decline
> Smoking
> Depression
> Diabetes
Why does some people’s intelligence age better than others? Protective factors (Brenda Plasman)
> Mediterranean diet
Eating more vegetable
Being in more professional occupations
Taking part in some leisure activities
What was found about health related to the Scottish mental surveys
Traced the Aberdeen sample (2792 children – 79.9%) via health records to vital status as of January 1997
Basically, looked to see if they were dead or alive up to 76 years
On average a girl with a 30 point disadvantage in IQ at age 11 was half as likely to be alive
(More intelligent men entered 2nd World War)
What did the Scottish mental survey 1947 find about the link between cardiovascular disease and intelligence?
As intelligence decreases, the risk of CVD is higher
As the intelligence test score at age 11 becomes higher and higher, the risk of death from this cause by age 79 steadily lowers.
What did Deary find was the biggest predictor of late life cognitive ability?
Intelligence score at 11
Why might there be a link between intelligence and life longevity?
Intelligence test scores at childhood already hint at departure from optimum health
Higher childhood intelligence leads to better education, jobs, and might have health advantages including being in safer environments
Intelligence test scores at childhood might represent better wired body overall, from birth or even earlier
‘system integrity’
Higher childhood intelligence associated with uptake of healthier behaviours and lifestyles
Did 11 year old IQ predict vascular dementia?
Yes, but not alzheimer’s disease
What did Wraw et al (1979) find out about health and intelligence?
Higher intelligence test scores in youth were associated with lower risk of:
High blood pressure (20%)
Diabetes (15%)
Lung Disease (29%)
Congestive Heart failure (34%)
Stroke (35%)
Also reported that those with 15 IQ point youth advantage less likely at 50 to smoke, drink heavily but more likely to workout etc
What sex differences were found between the 40k boys and 40k girls from the Scottish mental surveys?
Data was taken from 3 intelligence tests: the Moray House Test No 12 and two non-verbal tests (picture tests) – scores on all 3 were summed to give an overall IQ score (mean of 100 and SD of 15)
Larger number of girls in middle-scoring groups (90-110). Only small % difference
Larger number of boys in lower scoring group
(just under 60). % difference between girls and boys = 17.2 percent
Larger number of boys in higher scoring group
(130-140). % difference between girls and boys (red arrow) 15.4 percent
No difference in average intelligence of females (n = ~40k) and males (n = ~40k) at age 11 years
However, there were sex differences in the spread of IQ scores
More girls have IQ scores around the mean
Boys IQ scores more distributed at the lower and higher levels of intelligence
What did the National Longitudinal survey of youth (1979) find about sex differences in intelligence?
More recent study – post-adolescent American adults
Selected opposite-sex siblings from the overall sample to look at sex differences between them
Selecting opposite sex siblings matches them on family background and to some extent genetic factors
Participants took intelligence test called the Armed Forces Qualification Test with four subtests: arithmetic, word knowledge paragraph comprehension and mathematics knowledge.
A general intelligence score was calculated
Males show very small but significant advantage on the g factor extracted from the Armed Forces Qualification Test. Note, the effect size was tiny (Cohen’s d = 0.064).
Mean IQ scores were also significant but the difference equated to less than 1 IQ point between males and females – negligible!
A more marked difference was again in the spread of scores. Like the Scottish 11 year olds these more recently born US adults showed more males at the lower and higher extremes than females (but the overall means were the same).
What did the CAT test (2001) show about sex differences in intelligence?
Huge dataset representative of UK school children aged 11-12 years.
Overall intelligence test score favoured girls by about three quarters of an IQ point.
However, as with the Scottish 1932 11 year olds, there is a greater proportion of girls around the middle and greater proportion of boys around the extreme ends
Why are there more males with intellectual disabilities than females?
x linked mutations
Are there male-female difference for g based on Raven’s Progressive Matrices?
RPM assumed to be good measure of general intelligence (non reliance on language)
- Review of 120 studies prior to 1980 concluded there were no male-female differences in RPM (Court 1983)
- 2 meta-analyses concluded that in adults, men score higher than women by around 4.5-5 IQ points (Lynn & Irwing 2004, Irwing & Lynn 2005)
However, the male:female ratio in each sample didn’t match the male:female ratio for that country (recruitment effect could distort results)
Conclusions are therefore limited
Claimed that the male-female difference in RPM scores favouring males emerges from age 15 years onwards
However, while the sex difference in RPM scores is significant, the effect is small.
Conclusion: average difference between male and female Raven’s scores (g) if existent is very small. Otherwise, it would show up more clearly in national samples.
Is RPM a good measure of sex differences in g?
Issue with using RPM as a pure measure of g for male-female differences is that the scores contain a significant visuospatial reasoning component (which we will find out, there are moderate to large male-female differences in some types of visuospatial reasoning, which could drive the differences instead of g).
Are there sex differences in specific cognitive abilities? Verbal reasoning:
CAT3 has nine tests broken down into 3 cognitive domains: verbal reasoning, quantitative reasoning and non-verbal reasoning
> Verbal reasoning
Girls did better than boys by 0.15 of a standard deviation in verbal ability, which is equivalent to just over 2 IQ points.
More girls at the higher end. More boys at the lower end.
Are there sex differences in specific cognitive abilities? (Quantitative reasoning)
> Quantitative reasoning
Boys did better than girls by 0.03 of a standard deviation in quantitative reasoning, which is equivalent to less than half an IQ point
Are there sex differences in specific cognitive abilities? (Non verbal reasoning)
> Non-verbal reasoning
Girls did better than boys by 0.03 of a standard deviation in non-verbal reasoning, which is equivalent to less than half an IQ point
What are men and women on average better at: reading comprehension, perceptual speed and associative memory, mathematics and visuospatial reasoning?
On average, women do better than men (-ve values) in tests of reading comprehension, perceptual speed and associative memory
On average, men do better than women (+ve values) in tests of mathematics and visuospatial reasoning
What did the National Assessment of Educational Progress (NAEP) find out about sex differences in academic achievement?
Large sex differences in writing (females better than males)
Which spatial and verbal reasoning tasks are men vs women better at?
Men: (mainly spatial)
Visualisation
Spatial orientation (mental rotation)
Throwing accuracy
Visual interference
Mathematical reasoning
Women: (mainly verbal)
Perceptual speed
Object location memory
Word fluency
Fine motor coordination
Numerical calculation
Do men or women score higher on spatial abilites?
Meta-analysis:
Across all ages, men score higher on spatial abilities (small to medium effect size)
→ medium to large effect size for mental rotation
On average, men perform better on tests of spatial ability than women do
→ Spatial ability is the ability to visualise spatial relationships and to mentally manipulate objects
→ … such as spatial visualisation, visual interference and mental rotation
Do men or women score higher on verbal abilites?
Meta-analysis:
In women of all ages, the only effect size above .20 is for verbal production
→ effect size for verbal abilities is so small that it can be considered not to exist
On average, women do better on verbal ability than men.
→ … such as comprehension (the act of understanding the meaning, nature or importance of things) and language vocabulary (knowledge of words in a particular language)
What does PCOS tell us about a biological basis for cognitive ability differences?
Polycystic ovary syndrome (PCOS) is an endocrine disorder associated with elevated levels of free testosterone.
- Polycystic women demonstrated worse performance on tests of verbal fluency, verbal memory, manual dexterity, and visuospatial working memory than healthy control women.
- No differences between groups were found on tests of mental rotation, spatial visualization, spatial perception, or perceptual speed.
→ Women with elevations in testosterone levels reveal poorer performance on cognitive tests that show a female advantage.
What is the effect of stereotype threat on sex differences between maths ability?
Girls performed better in maths test when they were told that any anxiety could result from negative stereotypes that have nothing to do with their actual ability
What are evolutionary perspectives on sex differences in spatial ability?
Males
- Hunting - navigating back from covering great differences - hippocampus differences, requiring to track prey - constantly changing orientation
- Range size
- Warfare
Females
- Foraging - details over large open spaces
What is DNA described as by Denis Noble?
‘On its own, DNA is not a cause in an active sense. Ithink it is better described as a passive data base which is used by the organism to enable it to make the proteins that it requires.’
What is epigenetics?
Environmental factors influence the expression of genetic code generations later
Why are twin studies useful?
Comparing different twins provides natural experiment
Can compare people of the same age
In some cases they have same genetic make-up and in some they share half
If identical twins are more similar to each other on intelligence test scores than non-identical twins, we can infer that genes play a role
How is the environment divided in twin studies?
Common in twin studies to divide the environment into:
> Shared (common to both)
> Non-shared (unique to each)
Effect of genes on measurable traits (height, extraversion, intelligence etc.)
How is the extent of resemblance in intelligence measured in monozygotic twins?
One compares the variation of IQ scores within a twin pair, and the variation of IQ scores between multiple twin pairs
(Same calculations can be done for dizygotic twins)
What does calculating correlations for both monozygotic and dizygotic twin pairs tell us?
How similar identical and non-identical twins tend to be on the trait in question
What is genetic effect similarity in MZ twins compared to DZ twins?
Shared environment makes the same contribution
Assumed that genetic effect similarity has twice as much effect in monozygotic twins (therefore reported differences multiplied by 2)
What did Claire Hayworth find in her twin study of intelligence?
Dataset from multiple twin studies
4809 monozygotic twin pairs and 5880 dizygotic twin pairs
Four web-based cognitive tests. Three from WAIS for children and one Raven’s Matrices
General intelligence score calculated
Mean correlation (MZ) = 0.78
Mean correlation (DZ) = 0.51
Difference between twin types:
= 0.78 – 0.51 = 0.27
Therefore 54% of the differences in intelligence caused by genetic differences
(Twice the difference between MZ and DZ correlations, i.e. 0.27 x 2 = 0.54)
24% of differences caused by shared environment
(MZ correlation of 0.78 minus the genetic effect of 0.54)
22% of differences caused by non-shared environment
(1 minus MZ correlation of 0.78)
Roughly how genetic is intelligence?
About half the differences in intelligence are caused by genetic differences, half by environment
How does the genetic component of intelligence change with age?
% of intelligence differences caused by genetic factors increases with age
Genetic contribution to people’s differences in intelligence is larger in adulthood (66%) than in childhood (41%) and larger in adolescence (55%) than childhood
Contribution of shared environment declines from 33% in childhood to 18% in adolescence and to 16% in adulthood
Contribution of non-shared environment remains quite stable (around a 1/4th or 1/5th across the age range)
Why does heritability of intelligence increase with age?
One theory is that environments are more similar for any given pair of 65 year olds than a pair of 4 year olds so any differences in older people must be due to their genes
Another theory is that as children grow up, they increasingly select, modify and even create their experiences, which are based on their genetic propensities
What did the Minnesota Study of Twins reared apart (MISTRA) find?
139 twins pairs raised apart
76% intelligence concordance
(MZ twins raised together have 86%)
What happened to twins raised apart Jack and Oskar?
Jack and Oskar - Jack raised as a Jew in Trinidad and Oskar grew up in Nazi Germany and joined the Hitler youth
Reunited - other sides of political spectrum, but probably would have behaved in the same way if they were in opposite situations
What is the order of concordance rates of intelligence rom highest to lowest?
MZ twins reared together
MZ twins reared apart
DZ twins reared together
Biological siblings reared together
Parents and children living together
Biological siblings reared apart
What is the human genome and what are genome-wide association studies?
Human genome estimated to comprise of 3 billion nucleotides of DNA within 23 chromosome pairs
3 billion stretch has some structure
Genes – stretches of DNA coding for proteins
About 19,000 genes in human DNA
Genes code for proteins (made of amino acids)
Across the 3 billion stretch there are differences between ppl. At any one site, there is the commonest nucleotide for a given population.
Ppl. have a different nucleotide at about 1 in every thousand places, so a person likely to have 4-5 million places in DNA differing from the most usual nucleotide (called single nucleotide polymorphisms - SNPs)
What did Davies et al (2018) find out about SNPs and intelligence?
There were 11,600 significant SNPs, i.e. the number of single nucleotide variants related to intelligence test scores
Large numbers of genetic variants in a large number of genes related to people’s intelligence scores
The heritability of intelligence using this method (25%) is about half of that found using twin studies – gap should shorten with more genetic variation studies
Using people’s DNA, one can predict better than chance their intelligence differences - currently prediction not strong but should get better with more and more data
Still early days with other genetic variants other than SNPs to be studied
Also found some of the genetic variants related to intelligence also related to body and health traits including brain volume and longevity
What is the stability of intelligence like across our lifetime?
Cognitive abilities remain relatively stable from 25 to 65 years of age, then there is a decline
What is validity?
Validity refers to the question of whether the test measures what it claims to measure.
What is face validity?
An IQ test is said to have face validity if it “looks like” it is going to measure what it is supposed to measure
What is concurrent validity?
Intelligence test shows concurrent validity if it shows a (positive) relationship with other measures of intelligence.
What is predictive validity?
Intelligence tests have been used to predict ‘real-world‘ measures of intelligence or achievement (e.g. school achievement, job performance, etc.)
What is internal reliability?
Any measure of intelligence with good internal reliability will have a number of items that correlate positively with one other, this suggests they are measures of the same construct.
What is test-retest reliability?
A good intelligence test will show a good level of reliability over time. Your general intelligence is thought to be relatively stable over time. You would expect IQ scores to be very similar across test sessions.
What is the Flynn effect?
The scores on intelligence tests have a tendency to fluctuate.
The scores of intelligence tests change continuously from year to year.
Flynn (1981) discovered a year-on-year rise of intelligence test scores (whenever a new/revised IQ test was compared to an older/previous IQ test).
In particular, Flynn found that if a group of participants averaged an IQ of 100 on the original WISC (1947/1948), they averaged 108 on the WISC-R (1972).
→ in a period of 24 years the IQ gain from WISC to WISC-R was ~8 IQ points
What were the results of Flynn’s meta-analysis?
The highest rise in IQ occurred in the non-verbal tests (fluid intelligence; 5.9 IQ points per decade) and lowest gains were in verbal tests (crystallised intelligence; 3.7 IQ points per decade)
→ Due to better schooling? (However, IQ gains in verbal vs. non-verbal IQ should be reversed)
What are explanations of the Flynn effect?
NOT Generations are getting more and more intelligent
→ unlikely, we would expect to find more geniuses in the world
→ these gains are far too rapid to result from genetic changes
NOT Length of schooling
→ important, but mainly relevant for verbal tests
NOT Test-taking sophistication (people become more familiar with IQ tests)
→ does not explain the difference between verbal and non-verbal IQ tests
PROBABLY NOT Child-rearing practices (parents are more interested in their children‘s intellectual development)
→ some evidence, but educational programs have probably no lasting effects on IQ
PROBABLY NOT Cognitive stimulation hypothesis (visual and technical environment, TV learning)
→ little direct evidence
PROBABLY Nutrition (e.g. nutrition has been linked to brain size)
Nutrition as most plausible - cortical thickening and bigger brain - more intelligence in humans
What ways are there to measure the brain?
Brain structure (MRI)
> different types of brain tissue a person has
> can indicate how healthy brain tissue is
Brain function (fMRI)
> blood flow changes during mental tasks
Electroencephalographic (EEG, or brain waves) and brain evoked response methods
> electrical activity at rest / in response to stimuli
Magnetoencephalography (MEG) methods
> magnetic activity from electrical activity of brain
What do more intelligent brains look like? (Ritchie et al, 2015)
672 people around the age of 73 years
15 cognitive tests – many of them from WAIS
General intelligence (g) score calculated
MRI scans to measure to measure different types of structure in the brain
Correlations with g:
Total brain volume = 0.31
Brain cortical thickness = 0.24
Brain white matter integrity = 0.24
Brain white matter intensities = -0.20
What is total brain volume?
Total volume inside skull minus cerebrospinal fluid. How much brain, of any type of tissue, inside skull
What is brain cortical thickness?
Thickness of the brains’ grey matter – largely the neurons of the brain (info. processors)
What is brain white matter integrity?
Connecting network of ‘wires’ in the brain – the axons connecting nerve cells to one another. Lies mostly below grey matter of the cortex
What are brain white matter intensities?
Scars in the brain’s connections. More develop as we age. Could interrupt efficient processing
What is intellectual ability and cortical development like in children and adolescents?
Superior IQ group has a thinner superior prefrontal cortex at the earliest age
Rapid increase in cortical thickness in the superior IQ group (peaking at age 13, waning in late adolescence
(Dynamic neuroanatomical expression of intelligence)
- Thickening of cerebral cortex - closest measure to intelligence of participants
- Trajectory for superior IQ = thinning then thickening
What is the straw analogy for white matter?
- White matter - like straws - no holes, no dints, so that info (liquid) can flow through it well - or like a motorway
- Myelin sheath - white colour - fatty, makes info processing faster
- White matter intensities - scars in straws/motorway
What correlations have been found between brain volume and general intelligence?
0.29 and 0.28
Overall, what brain features predict higher intelligence?
Thicker grey matter on surface of brain
Healthier white matter connections overall
Fewer white matter scars causing ‘leakage’
A larger brain overall. Why? Answer not fully known – possibly greater numbers of nerve cells
How many brain cells do we have and what do they do?
Brain made up of around 100 billion brain cells (building blocks of cognition)
Each one acts like a small chip – collect, process and pass on information via electrical signals
What are dendrites?
Long projections on cells to collect signals
How did Goriounova et al (2018) conduct their study of whether smarter brains are equipped with faster and larger brain cells?
Studied 46 people who needed surgery for brain tumours or epilepsy
Each took a WAIS IQ test before the operation, and a block of brain tissue was obtained away from the epileptic focus or tumour, and displayed no structural / functional abnormalities
Vast number of brain cells in human neocortex, so even slight change in neuronal efficiency could translate to large differences in mental ability
What do dendrites of people with higher IQs look like?
Goriounova et al. (2018) - biological cellular evidence that individuals with a higher IQ possess larger / more complex dendrites and are able to sustain faster action potentials
In conditions of high cognitive demand, like during an IQ test, larger and faster neurons can help to process information quickly and efficiently
What did Goriounova et al (2018) find from their study of whether smarter brains are equipped with faster and larger brain cells?
IQ scores positively correlate with cortical thickness of the temporal lobe
Average total dendritic length in pyramidal cells correlates with cortical thickness in temporal lobe
Indicates that dendritic structure of individual neurons contributes to the overall thickness of cortex
Average total length and number of dendritic branches in pyramidal cells correlates with IQ scores
Higher IQ scores are accompanied by faster action potentials
What is the role of pyramidal cells in intelligence?
Pyramidal cells – abundant in cerebral cortex of virtually every mammal studied
Primarily found in brain structures associated with advanced cognitive functions, e.g. intelligence
Pyramidal cells are the primary excitation units in cortex - integrators and accumulators of synaptic information
What is working memory and which type of intelligence is this crucial for?
Widely accepted theory that working memory is crucial for fluid intelligence (gf), that is the ability to use inductive, deductive, and quantitative reasoning to solve novel, “on-the-spot” problems
How did Gray et al (2003) test whether fluid intelligence (gf) was mediated by neural mechanisms supporting working memory?
48 healthy participants
Raven’s Advanced Progressive Matrices, widely used measure of gf, was administered before fMRI session
They probed individual differences in general fluid intelligence and looked to see if these differences corresponded to differences in brain activity
Measured performance on the n back task (included lures to increase attentional demand)
What did Gray et al (2003) find out about whether fluid intelligence (gf) was mediated by neural mechanisms supporting working memory?
There was a positive correlation (0.36) between accuracy on ‘Lure’ trials (higher interference working memory) and fluid intelligence (Raven’s)
fMRI showed that activity in left lateral Prefrontal cortex in correct ‘Lure’ trials correlates with fluid intelligence on Raven’s Matrices (r=0.46)
Conclusion: Participants scoring higher on Raven’s Matrices Tests (fluid intelligence) were more accurate in a challenging working memory task during which left Prefrontal cortex was heavily engaged
A good working memory supports fluid intelligence (gf) with left lateral Prefrontal cortex activity partly mediating this cognitive process
How did Seidlitz et al (2018) investigate whether smarter brains were more connected than others?
Mapping the connections in the brain – known as the connectome
296 healthy adults / adolescents (14-24 years) and validated with a second cohort of 124 volunteers
Used multimodal MRI to build ‘morphometric similarity networks (MSNs)’ to show how well connected an individual’s brain regions are
Built a map showing how well connected the ‘hubs’ were
Investigated relationship between interindividual differences in brain network topology and interindividual differences in general intelligence
Predicted specifically that individual differences in IQ should be related to individual differences in nodal degree
What are hubs in the brain?
High number of pyramidal neurons that can simultaneously capture multi dimension info during higher cognitive functions
Hubs can coordinate activity of large populations of globally distributed neurons
What did Seidlitz et al (2018) find out about whether smarter brains were more connected than others?
MSN degree related to verbal and non verbal IQ
High degree (highly connected) hubs identified in left frontal and temporal cortex, which were highly predictive of higher IQ score
We saw a clear link between the ‘hubbiness’ of higher-order brain regions – in other words, how densely connected they were to the rest of the network – and an individual’s IQ. This makes sense if you think of the hubs as enabling the flow of information around the brain – the stronger the connections, the better the brain is at processing information.”
Jakob Seidlitz
Broadly, what are all of the brain elements that higher intelligence scores correlate with?
Larger whole-brain volume
Thicker grey matter on brain surface (cortical thickness)
Larger / more complex dendrites and faster action potentials
Good working memory (partly mediated by PFctx)
Highly connected higher-order brain networks
(hubs)
