Module 30 Page 1
The Origins of Intelligence Testing: Alfred Binet: Predicting School Achievement
Intelligence Tests - a method for a assessing an individual's mental aptitudes and comparing
them with those of others, using numerical scores.
Mental Age - a measure of intelligence test performance devised by Alfred Binet; the
chronological age that most typically corresponds to a given level of performance. Thus, a child
who does as well as the average 8-year old is said to have a mental age of 8.
Binet hoped his test would be used to improve children's education, but feared it would be used
to label children and limit their opportunities.
Lewis Terman: The Innate IQ (1877 - 1956)
• Terman discovered the Paris developed questions and age norms worked poorly with
• Terman extended the upper end of the tests range from teenagers to superior adults
calling the revision the Stanford-Binet - the widely used American revision of Binet's
original intelligence test.
• German psychologists William Stern derived the famous Intelligence Quotient/IQ -
defined originally as the ratio of mental age (ma) to chronological age (ca) multiplied by
100. On contemporary intelligence tests, the average performance for a given age is
assigned a score of 100.
Modern Tests of Mental Abilities
Achievement Tests - a test designed to assess what a person has learned
Aptitude Tests - a test designed to predict a person's future performance, aptitude is the
capacity to learn.
Wechsler Adult Intelligence Scale (WAIS) - is the most widely used intelligence test; contains
verbal and performance (non-verbal) subtests.
The latest edition of WAIS consists of 15 subtests including;
Letter-number sequencing Module 30 Page 2
not only does it yield an overall intelligence score but also separate scores for verbal
comprehension, perceptual organization, working memory and processing speed.
Principles of Test Construction: Standardization
Standardization - defining meaningful scores by comparison with the performance of a
Normal Curve - the symmetrical, bell-shaped curve that describes the distribution of many
physical and psychological attributes. Most scores fall near the average, and fewer scores lie
near the extremes.
Reliability - the extent to which a test yields consistent results, as assessed by the consistency
of scores on two halves of the test or on retesting.
Validity - the extent to which a test measures or predicts what is supposed to.
Content Validity - the extent to which a test samples the behaviour that is of interest.
Predictive Validity - the success with which a test predicts the behaviour it is designed to
predict. It is assessed by computing the correlation between test scores and the criterion
• Intelligence scores correlate even more closely with scores on achievement tests.
• The SAT tests used in the USA are less successful in predicting first-year college
• When we validate a test using a wide range of people. but then use it with a restricted
range of people, it loses much of its predictive validity. Ex. GRE for those applying to
grad school. Why does the predictive power of aptitude scores diminish as students
move up the educational ladder?
The Dynamics of Intelligence
Stability or Change: Aging and Intelligence
Phase I: Cross-Sectional Evidence for Intellectual Decline
Discovering older adults give fewer correct answers on intelligence