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Intelligence and IQ Cheat Sheet (DRAFT) by

Intelligence and IQ summary sheet Includes: Measurements Validity Causes of Individual Differences

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Why study intell­igence?

Basic science
As psycho­logical students, it is our duty to understand why people vary in this trait
Your life depends on it
Intell­igence is a very important predictor of a number of important outcomes in life. By better unders­tanding individual differ­ences in intell­igence, we can help build better societies.
Intell­igence is the solution to every single problem that is soluble.
Every problem that exists-and every problem that permits of a soluti­on-can be solved provided we have sufficient intell­igence.

History of Intell­igence

Pioneered in 19th century by:
Alfred Binet (French)
Binet developed the first test of intell­igence in 1905=asked by the French government to develop a method to identify children in need of special ed.
Collab­orating with Theodore Simon, he created the Binet-­Simon Scale = included 30 tasks of increasing diffic­ulty. It was developed to be approp­riate to the develo­pment of children aged 3-10.
Francis Galton (English)
Galton was interested in the hereditary nature of intell­igence. He was also the first to propos­e-and test- that there were individual differ­ences in intell­igence.
Stanfo­rd-­Binet test
For US children.
Used this test with repres­ent­ative samples of children.
Standa­rdized testing
one child's score could be meaningful compared to others.
Intell­igence Quotient (IQ)
William Stern
Stern noticed that the child's mental age (measured by the Binet-­Simon scale) varied propor­tio­nally to their chrono­logical age.
A 5 year old child with the mental age of 4 year old, will have mental age of an 8 year old when 10 years old.
Stern developed formula for calcul­ating IQ: (mental age/ chrono­logical age) x 100
The ratio one's mental age divided by their chrono­logical age is their IQ
This permitted a "­nor­mal­" IQ to be 100
Raymond Cattel
Cattel accepted the validity of g, but suggested that g is compro­mised of two related but distinct forms of general intell­igence.
Crysta­lised and Fluid Intell­igence
Crysta­lised Intell­igence (GC) reflects aquired knowledge and skills i.e. factual knowledge. Measured with tasks indicatin breadth and depth of the knowledge of the dominant cultue. Measures of compre­hension and vocabulary ability are indicators of crysta­lised intell­igence. It is also expectedto increase over one's lifespan as as cumulative learning increases
Fluid Intell­igence (Gf)= represents reasoning that is indepe­ndent of cultural influence/ It is the ability to arrive at unders­tanding relations among stimuli, comprehend implic­ations, and draw infere­nces. It measures of acquis­ition of new knowledge, patter recogn­ition, and analogous reasoning and indicators of fluid intell­igence. It is expected to be present at birth and be stable throughout adulthood.

How We Measure Intell­igence?

There are three measures of intell­igence that are predom­inately used in psycho­logy.
The Stanfo­rd-­Binet Test
The Wechsler Test
Raven's Progre­ssive Matrices
The Stanfo­rd-­Binet Test
Designed to be used with people ages 2-20+ years.
Measures five Stratum II abilities: fluid reasoning, knowledge, quanti­tative reasoning, visual­-sp­atial proces­sing, and working memory.
Also measures General Intell­igence ( g )
Wechsler Tests
Wechsler Adult Intell­igence Scale (WAIS)= 16-90
Wechsler Intell­igence Scale for Children (WISC) = 6-16
WAIS-IV = is admini­stered online or using a paper-­and­-pencil format. It includes 10 core subtests and 5 supple­mentaal tests. Takes 60-90mins to complete. WAIS-IV measures 4 strantum II dimensions of Intell­igence: Verbal Compre­hen­sion, Perceptual Reasoning, Working Memory and Processing Speed. Also measures general intell­igence (g)
WISC can be admini­stered digitally or usingpaper and pencil format. Takes approx­imately 60mins to complete. Five Stratum II dimensions are measured: Verbal Compre­hen­sion, Visual Spatial Reasoning, Fluid Reasoning, Working Memory and Processing Speed.
Raven's Progre­ssive Matrices
First published in 1938
Different to Wechsler's Tests but they too are designed to measure general intell­igence.
John Raven believed that the best way to measure the abstract phenomenon of g was a scale free of all cultural influe­nces, partic­ularly language.
The Raven's matrices require non-verbal problem solving skills.
Test Includes 60 itens distri­buted across five sets of items
The items are ordered in increasing levels of difficulty
Can be used with child and adult samples.
Takes 40mins to complete.

What are These Tests Measuring?

General intell­igence (g)
However, each tests measures no more than 3-5 of the broad domains of intell­igence
A thorough assessment of intell­igence requires the admini­str­ation of one or more additional intell­igence tests measuring different abilities at Stratum II.
Do IQ tests actually measure intell­igence?
A consistent finding in criminal psychology is that lower levels of IQ are strongly associated with an increased risk of criminal behaviour. Most research suggests that low IQ is casual factor in criminal behaviour.

Causes of Individual Differ­ences

What Causes variation in IQ
Geneti­cs=­ove­rwh­elming evidence that genetic factorsare important in expanding variation in IQ scores. Genetics become more important as people age. As people age they can shape their enviro­nment to greater degree- a person with an aptitude for mathem­atical reasoning might focuson math based subjects in school, study math based subjects in univer­sity, and go on to work as a computer engineer. Your enviro­nment becomes shaped by your underlying aptitudes which are themselves genetical influe­nced.
The American Psycho­logical Associ­ation taskforce for intell­igence highli­ghted four enviro­nmental factors for relevance:
Biological Factors: Better nutrition leads to increased levels of IQ. Iodine supple­men­tation in deficient areas leads to higher IQ. Supple­men­tation with different vitamins, iron and magnesium increased children's fluid intell­igence by 9 points (Bento and Roberts 1988). Exposure to lead in the enviro­nment has been shown to decrease IQ levels through childhood and adoles­cence.
School and Education: education and IQ are highly correl­ated, and there is longit­udinal evidence that better education leads to increased levels for IQ.

The Flynn Effect

Discovery that mean IQ levels are increasing over time all over the world
Why us The Flynn Effect occurring?
Pieysching and Voracek (2015) have provided several sugges­tions
Educat­ion­=more years spent in education likely explains gains in crysta­llised intell­igence (not fluid)
Exposure to techno­log­y=more stimul­ating enviro­nments could explain gains in fluid intell­igence
Decreasing family sizes=rise of 1.4 points per decade can be attributed to smaller family sizes
Test Taking behavi­our­=in­creased frequently of test taking may improve perfor­mance on IQ tests.
Hybrid vigour=the mating of indivi­duals from dissimilar subpop­ula­tions
Blood lead-level reduct­ion­s=r­educed amounts of lead in the enviro­nment could explain gains in IQ.
Genomic imprin­tin­g=e­nvi­ron­mental conditions affect reprod­uction inform­ation (i.e., male sperm) and ultimately genetic expres­sions in children and even in grandc­hil­dren.
Improved Nutrit­ion­=better nutrition can bolster IQ.
Reduced pathogen stress­=in­creased hygiene leads to fewer infectious diseases in childhood. This means more bodily resources devoted to cognitive develo­pment.
Decreased IQ variab­ility= reduced nr of people at the extremes of IQ (low end) would lead to increased mean IW levels.
Social multip­lie­rs=­env­iro­nmental gains lead to higher IQ and higher IQ leads to better enviro­nments which leads to higher IQ and so on.
Life History speed-­'slow life history' indivi­duals are typically charac­terized to have fewer lifetime sexual partners, fewer offspring and later parent­hood, as compared with 'fast life history' indivi­duals.
When pathogen stress is reduced and adequate nutrition is ensured, the develo­pment of slower life history speed is encour­aged, thus allowing the emergence of differ­ent­iated cognitive abilities.