UNIT 2 - TOPIC 1

Intelligence

a hypothetical construct that is associated with human characteristics like ability to learn, remember, problem-solve and comprehend (cognitive skills).

Psychometric approach of intelligence

based on the belief that intelligence can be measured like physical attributes such as height or weight.

Two commonly used IQ tests or scales

the Stanford-Binet IQ test and the Wechsler Intelligence scale. These two are IQ tests which determine the IQ of a person.

Stanford-Binet IQ test

Measures skills needed for school success. Based on Binet’s idea that ability increases with age, so it uses age-graded, adaptive questions. IQ is calculated as IQ = MA (mental age) / CA (chronological age) x 100. Children's whose mental age = their chronological age are considered to have regular intelligence (about 100). It assesses 5 cognitive factors which are fluid reasoning, knowledge, quantitative reasoning, visual–spatial processing and working memory. The population that this test is aimed at is very broad and can vary from around 2-85 years.

Wechsler’s intelligence scales

by David Wechsler and is used to find the IQ of a person by testing their verbal comprehension, perceptual reasoning, working memory, and processing speed which provide a full-scale IQ score. There are two of these tests with one of them aimed at 6–16-year-olds and the other aimed at 16–90-year-olds.  

Reliability in intelligence tests

when the same results can be expected with the same subjects under the same conditions in different occasions.

Validity in intelligence tests

if the results measure what it was designed to measure. Also by checking how well the results correspond to established theories and other measures of the same concept.

What are traditional intelligence tests influenced by?

nature and nurture

Nature in intelligence

Genetic inheritance that influences a person’s IQ and sets their potential range of intelligence.

Nurture in intelligence

Environmental factors that influence where within the genetic range a person’s IQ will fall.

What studies help psychologists determine the roles of nature and nurture in intelligence?

family, twin and adoption studies

What is the Minnesota Study of Twins Reared Apart?

they measured IQ in over 100 pairs of MZ twins raised apart (MZA) and compared their IQ correlations to those of MZ twins raised together (MZT).”

What were the findings in the Minnesota Study of Twins Reared Apart?

The Minnesota study found IQ correlations of 0.76–0.88 for identical twins reared together and 0.64–0.78 for identical twins reared apart, showing that twins with the same genes tend to have very similar IQs (nature), even when raised in different environments. However, because the correlations were less than perfect, this also highlights the role of environment (nurture). Researchers estimated a heritability of about 0.70, suggesting that genetics accounts for roughly 70% of intelligence, while the rest is shaped by environmental influences, consistent with the reaction range theory.