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  • Created by: Ross Hill
  • Created on: 18-05-16 11:06

What is Intelligence?

Intelligence --> the global capacity to profit from experience and to go beyond given info about the environment 

Intelligence Quotient (IQ)--> index derived from standardised tests of intelligence, originally obtained by individual mental age/chronological age x100. Now it is directly computed as an IQ test score

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History of Intelligence Testing

Alfred Binet; Identify children who would benefit from remedial education

  • Binet assumed that intelligence= capacity that matters for many tasks --> good at many tasks means you are intelligent
  • IQ scores reflected a composite of performance on all tasks --> general ability

William Stern's Intelligence Quotient;

  • IQ= Mental Age/Chronological Age X100
  • Mental Age--> level of development reflected in test performance 
  • Chronological Age --> expected score at current age of test
  • Same Mental & Chronological Age=100
  • 8yr old answering 10yr old questions= 125
  • BUT... 50 year old with mental age of 20yr old cant have and iq of 40

Recent IQ Tests;

  • Weschler Intelligence Scale for Children v4 (WISC-IV)
  • Weschler Adult Intelligence Scale (WAIS-IV)--> Variety of verbal and performance tasks. Seperate sub tests assess WM and speed of intellectural processing
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Recent IQ Tests- Raven's Progressive Matrices

Test single specific capacities like the ability to perceive patterns

Minimise influence from verbal skills/ background knowledge

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Principles of Test Construction

Reliability --> Need to evaluate how consistent a measure is in its results

  • Using test-retest reliability
  • Intelligence tests have a high test-retest reliability e.g. age 6 and 18
  • HOWEVER.... substantial change in environment can affect stability

Validity --> Does the test really measure what its intneded to measure

  • Predictive Validity --> Assesement of whether a test measures what its suppost to measure, based on whether test score correlates with another relevant criterion measured later
  • Results= Good predictive validity for academic and workplace performance in more complex jobs

IQ Heavily influences life outcomes--> larger earnings, higher prestige careers, live longer, less likely to die in accident, less likely to struggle to follow doctor's instructions

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What is Intelligence?/General Vs Specific

Binet--> IQ= Singular ability that can apply to any context

      Score= General Intelligence--> a capacity that would provide an advantage on any mental task    

Alternative View;

          IQ= Level of achievement produced by a person's collection of more specific talents

          Strengths and Weaknesses. 1 Score=Crude Summary

Psychometric Approach to Intelligence--> looking for patterns of actual test scores

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Factor Analysis


  • Scores on subtests tend to be highly correlated with each other
  • Tests not independent of each other overlap in what they measure

Factor Analysis;

  • Statistical method for studying interrelations among tests
  • Distils from a pattern of correlations a broad summary of how they are all related
  • Common factors shared by several scores
  • 2 subtest scores are correlated they are influenced by the same factor
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General Intelligence

A general factor (g) is general intelligence --> mental attribute that is hypothesised as contributing to performance of virtually any intellectual task

Spearman thought g was the core of human intelligence

g's give a huge advantage

Spearman argued that each subtest depends on g and specialised ability

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Mental Speed

IQ takes time as it requires complex mental processes

Hypotheses suggest high IQ people are fster in all mental steps or those needed for mental retrieval

HOWEVER.... could be differences in brain structure that lead to differences in mental speed;

  • Greater myelination in brain neurons
  • Greater availabilty of metabolic fuel for neurons

Simple and choice reaction times are negativly correlated with intelligence. Suggests that intelligent people have brains that operate quiker and more efficiently 

Less energy consumption with a higher IQ- more efficient brain

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Working Memory Capacity

Working Memory Capacity --> measure of how efficiently a person can manage multiple mental processes at once

Tasks can involve;

  • Multiple bits of info that need to be kept track of
  • Multiple steps which demand a shif of focus from one moment to the next

Intelligent people may have;

  • Good working memories- keep multiple goals in mind
  • Good control of attention

Executive Control --> launch mental actions, redirect attention, shift strategies

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P-FIT Theory of Intelligence

Parieto-Frontal Integration Theory of Intelligence (Jung and Haier, 2007);

  • Intelligence arises from integration of activity among a network of brain slices associated with attention, working memory and language proessing among others 
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Beyond IQ Test: Practical Intelligence

Important predictor of business success

Analytic Intelligence--> ability measured by IQ Tests and crucial for academic success

Practical Intelligence --> ability to solve everyday problems through skilled reasoning that relies on tacit knowledge 

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Beyond IQ Test: Emotional Intelligence

The ability to understand your own and others emotions and control your own emotions appropriately 

Emotion plays a role in;

  • Guiding problem solving and decision making
  • Guiding our attention
  • Shaping what we remember

Emotion and Cognition interact

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Beyond IQ Test: Multiple Intelligences

Lingustic, Logical-Mathematical, Spatial, Musical

Bodily Kinesthetic -->ability to learna and create, Complex patterns of movement 

Interpersonal --> ability to understand other people

Interpersonal --> ability to understand ourselves

Naturalistic --> ability to understand patterns in nature

Gardner, 1983 & 1999

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Beyond IQ Test: Culture and Intelligence

Understanding of intelligence needs to take into account cultural context

Different Cultures have;

different concpetions of intelligence

different ideas on proper procedure for assesing intelligence

affects how cultures respond to westernised test


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Origins of Intelligence: Nature vs Nurture


Extent of contribution from each varies person to person;

  • Genetics- eye colour
  • Environment - language spoken (ability to learn language depends on genetics)
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Origins of Intelligence: Genetic Influence

Correlation between IQ of parent and child is +40

Correlation btween IQ of biological siblings +40

Similar genetics or environment?

Mz Twins have more similar IQs (.86) than Dz Twins (.60)--> must be a genetic component

Mz Twins have similar IQ regardless of whether the twins were raised in the same household oR apart (.75)

Adopted children have an IQ more in common with bith parents and not adoptive parents--> Genetics more important than environment 

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Origins of Intelligence: Environmental Influence

Correlation between sibling IQ is less when born further apart--> family circumstances may have changed grew up in seperate environments

Impoverished environments can impede intellectural development;

  • Longer a child has no/little schooling the lower IQ
  • Correlation of 0.40 between IQ Scores and Socio-economic status
  • Improved environment can improve Intelligence

IQ of children adopted out of horrible environments in which they had been abused or neglected --> after adoption IQ was markedly higher especially if adopted into a family with higher Socio-economic status

Flynn Effect--> worldwide improvement in IQ scores observed over the last few decades

             Many countries. Stronger fluid intelligence

             Better nutrition and healthcare?

             More exposure to info and perspectives

             Cannot be genetic as the increase is too quick

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Heritability Ratio

Heritability Ratio (H)--> a measure of the relative weight of genetic and environmental factors in determinng variability of a given characteritic within a population 

Value of H depends on particular population & degree to which variability within a population can be attributed to genetic variance

Fall between .40 and .70;

  • 40-70% variance=genetic
  • Genetics and environment equally important 
  • Middle class children lower heritability than middle class

Example--> phenylketonuria (PKU)= Cant digest phenyalanine so its converted to a toxin --> mental retardation 

          Genetic origin but variation is largely due to the environment 

H only reflects certain circumstances in particular groups

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IQ Comparisons

Between group differences may be due to environmental factors 

Within group differences reflects genetic variation 

Sources of differences can be diminished by approrpriate changes to the environment;

  • Improving nutrition
  • Health Care
  • Education
  • Combating Stereotypes 
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