Origins of IQ testing

General Intelligence (g, g-factor)

A statistical factor that captures what is common across lots of different mental tests. If you tend to do well on many different tests, you are said to have higher g

Specific intelligence

Abilities that are more narrow or specialised. Can be stronger in one area than another

savant syndrome

A condition where someone demonstrates exceptional aptitude in one domain, such as art or mathematics, with such aptitude often coinciding with some form of social or intellectual impairment

IQ (intelligence quotient)

A single score meant to summarise someone’s performance on an ‘intelligence test’ compared to the general population. Modern IQ scores are based on how far above or below the average (100) a person scores

Mental age

In early IQ tests: the age level at chich a child is performing.

Chronological / physical age

Your actual age in years

IQ ratio (stems formula)

IQ = Mental age / Physical age x 100

e.g. mental age 8 / physical age 10 × 100 = IQ 80

Norm-referenced / relative measure

Scores are meaningful only compared to a large group (the north sample) of people of the same age. IQ is defined relative to othersm not as an absolute quantity

Ordinal Measure

a scale that tells tou the order (who scored higher or lower), but not "how much” more ability someone has. IQ is treated as ordinal: 120 is higher than 100, but not 20% more intelligence

Independent criterion (of intelligence)

an external measure that we treat as a standard to jusge a test against

Consequential behaviour

Real-world outcomes we care about, such as school success or job performance, that we might want intelligence tests to predict

standarised tests

a test that is given and scored in the same way for eveyone, under the same conditions, so scores can be compared fairly across people

normal distribution/ “bell curve”

a common pattern of scores where most people are in the middle, and fewer people are very high or very low. IQ scores in a large sample tend to form a bell-shaped curve

Average IQ

abour 85-115 (68%)

Gifted

IQ around 145, less than 1%

Are the specific savant abilities evidence of high intelligence

Extrodinary but narrow mental ability is not what is usually considered evidence of high intelligence by many researchers

however research raises qustions on the existence of multiple intelligences in the areas were savants appear

Specific intelligences

Verbal

Mechanical

Spatial

Math

Normal distribution of IQ

IQ scores from a bell curve with mean 100 and SD 15

Sir Francis Galton contribution

• founder of differential psychology

• founder of experimental psychology

• forefather of intelligence test via sensory tasks

• wanted to measure differences in mental ability - founded psychometrics

James McKeen Cattel’s mental tests

Early sensory and reaction-time tests intended to measure intelligence

Cattells findings

mental tests scores did not correlate with eachother or with college grades

Alfred Binet

Created the first practical intelligence test for children, the Binet-Simon scale

Purpose of Binet-Simon scale

to identify children needing additional educational support using age-graded tasks

used childrens age as an indpendent citerion of intellectual competence

used a relative or normaltive measure of intelligence

Sterns contribution

coined the term IQ to see if child is developing normally - examine the ratio og child’s mental age to physical age

Lewis tERMANS ROLE

Revised binet’s test into the Stanford-Binet, popularisinf IQ testing in the US

Robert Yerkes Army Alpha/Beta tests

Large scale group intellligence tests used in WW1 for literature and illiterate recruits

why mental age becomes problemantic after 16

cognitive development plateaus, making age based comparisons meaningless

Why IQ must be age matched?

Scores only make sense relative to people of trhe same age group

Key limitation of IQ as a measure

it is not absolute; only ranks individuals and has no true zero

advantage of using tests

• easy to do

• less time consuming

• larger samples

• standardised