PSYC 213 Lecture Notes - Lecture 21: The Bell Curve, Iq Classification, Neuropsychological Assessment
11 May 2018
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PSYC 213 (April 10th) Intelligence: Measurements & Theories
“The true sign of intelligence is not knowledge but imagination.” - creativity
How does the idea of intelligence relate to cognitive processes.
“You are standing on the surface of Earth. You walk 1 mile south 1 mile west & 1 mile north. You end up exactly
where you started. →here are you?” – tries to measure people intelligence by measuring people inside ability for
problem solving.
• Intelligence is generally thought to related to efficient & appropriate decision-making
• Ability to learn from experience
• Adapting to ones environment
• Acting purposefully
• Intelligence is all about individual differences – measuring intelligence differentiate people from one another on a
cognitive level. – it represents individual differences
• Tests (IQ) have been designed to measure general intelligence differences.
• In cognition in general, we can measure differences in processes in a couple of ways
o Measure cognition by testing people’s performance on some task (objective measure)
o Ask people about their abilities (subjective, self-estimates)
Self-estimates of intelligence
• Men tend to give higher estimates of their intelligence than women
• American university students were asked to estimate their own IQ scores & parents.
• Compared to males, females students underestimated their scores – females attributed higher IQ scores to other
people compared to themselves more often than males.
• Both M/F gave higher IQ estimates for their fathers than their mothers
• Shows a gender bias that we have on how we think about intelligence
• Interpretation: there is a gender bias in how intelligence is viewed – as a masculine trait. What are the
consequences of this bias?
3 main uses of IQ scores.
1. Clinical & neuropsychological assessment – establish baseline levels of functioning
Scores can be used to help to see if theres any change in performance – when someone recover after stroke or
surgery.
2. Educational placement – see if a child needs more help than others to keep up in the class
3. Career assessment – determine a person cognitive strengths & help them find a career.
Measuring intelligence
• IQ scores are standardized tasks. The idea of standardized testing comes from the field of psychometrics – the
study of the theory & use psychological assessment
• Concepts related to psychometrics & testing
• Standardization 0 test scores are compared to pre-tested “standardization” or “norm groups”
• Scores are normally distributed
o The normal curve – symmetrical bell-shaped curve that describes how people scores are distributed in the
population, test score distribution.
o The psychometrics of IQ classification follow a normal distribution
o Mean (average) of 100 and standard deviation (variation) of 15. On average, a person will have an IQ 100
o The normal curve means that 95% are w/i 2s.d. of the mean – IQ scores between 70 & 130
o 60% of people are in 1 s.d. of the average score (85-115)
o If someone has an IQ > 140 = genius
The start of intelligence testing
• Francis GALTON (1822-1911) – intelligence can be measured scientifically by giving people reaction time tests
to identify stimuli (ex. sounds). The speed of reaction will tell you how intelligent you are.
• Founded the eugenics movement – racially-motivated view of how to “improve” society by using intelligence
measurements. He thought the upper white people had a higher mental ability. And according to him, this
individuals should have children. The low class non-white was thought to have a lower mental ability and should
not reproduce.
• Illustrates the influence of race & culture stereotypes in the development of intelligence tests.
• “The bell curve” book published in 1994 – intelligence is predicted by environmental & genetic factors
o Ethnicity & race can predict intelligence, which predicts jobs status, financial activity, even if a kid is born
outside of marriage
o There is a cognitive elite
find more resources at oneclass.com
find more resources at oneclass.com
o Heavily criticized both academically & in the greater community
Poor statistical support – not statistically supported
The ideas rest on false assumptions
• Alfred BINET – developed a test in response to the French government’s request to identify children that needed
special education. Only later used as an intelligence measure.
• For Binet, intelligence is important for:
o Practical life. He didn’t think intelligence could be measured by a test but more related to everyday life.
o Adapting to circumstances
o Judging and reasoning well
o He thought it was very complex, difficult to measure.
The Simon-Binet Test
• Uses the performance method: assess intellectual skills & knowledge by determining the ability to correctly
answer questions.
• Used empirical evidence to create questions to determine child’s mental age. He didn’t just make up what he
thought it should be included in the test to measure what the kids should be thought in school. But rather, he
gadered evidence about the type of knowledge & skills that the average school child of a given age would know
and use that to create questions.
• 30 questions given with increasing level of difficulty (easy hard)
• Easy items (to young children) – follow light beam, state your family name
• Difficult items( designed for more educated, older children) – repeat 7 digits, say the difference between 2 things,
describe abstract words.
• For the number of questions answered correctly, child was given a mental age calculated, compared to average
children.
• Stanford-Binet test was developed by Lewis Terman (at Stanford) – he adapted the Simon-Binet test with new
items to measure intelligence as the capacity to form concepts.
o His idea about intelligence suggest you can measure it (as opposed to Binet) & that you could give a number
that would tell you how intelligent someone is.
o Measures intellectual abilities at different ages.
• The basis of the modern day IQ test
o Item for a 4 y.o – repeat the following number: 3,6,7
o Item for an Adult – describe the difference between misery and poverty.
o IQ scores are calculated with the ratio method ((mental age)/Chronological age))*100
o If MA = CA – IQ is 100
o If MA > CA – ability is above average of peers (gifted)
o If MA < CS – ability is below average of peers (delated)
o The ratio method used to classify people based on their mental ability
o Test became very popular – popularized the idea that we need to measure intelligence
o The Army began using similar measures to recruit personnel
o This test was poorly standardized – the comparison group used to calculate the score was not well selected.
Weschler Tests – designed separate intelligence scales for children (WISC) & adults(WAIS)
• He thought that Stanford-Binet test didn’t measure intelligence bc initially, it was designed for children
• Separate/include 2 subscales to measures different types of intelligence.
• Test reports someone full IQ (FSIQ), which is made of Verbal IQ (VIQ) and Performance IQ (PIQ)
• 14 separate subtests used to compute that full scale IQ + verbal + performance
• Can compare someone’s performance on subscales in the verbal & non verbal component to see if there’s a
specific type of functioning that’s affected in the individual (diagnose mental deficiency).
o Similarities – explain what 2 words have in common “In what way are these 2 things alike”
o Easy item – Bus, Bike (both weels)
o Difficult item – bird, flower (both nature)
o Measures someone’s ability to analyze relationships & engage in abstract thinking
• Vocabulary – define words “ what does the following word mean?”
o Easy item – vacation
o Difficult item – panacea (cure for all diseases)
• Picture completion – determine what’s missing from a picture
• Picture arrangement – organize pictures in a logical, correct sequence, order.
• + This test is good for acknowledge different types of abilities
• - can be culturally biased & affected by language
Raven’s progressive matrices – try to assess someone’s intelligence w/o bias
• Thought to measure intelligence w/o influence of linguistic ability bc it’s a non verbal test
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Psyc 213 (april 10th) intelligence: measurements & theories. The true sign of intelligence is not knowledge but imagination. - creativity. How does the idea of intelligence relate to cognitive processes. You are standing on the surface of earth. Here are you? tries to measure people intelligence by measuring people inside ability for problem solving. Intelligence is generally thought to related to efficient & appropriate decision-making: ability to learn from experience, adapting to ones environment, acting purposefully. Intelligence is all about individual differences measuring intelligence differentiate people from one another on a cognitive level. It represents individual differences: tests (iq) have been designed to measure general intelligence differences. In cognition in general, we can measure differences in processes in a couple of ways: measure cognition by testing people"s performance on some task (objective measure, ask people about their abilities (subjective, self-estimates) Interpretation: there is a gender bias in how intelligence is viewed as a masculine trait.
