Class 11
XIX-XX c. developments in:
Psychometrics and Psychophysics
Psychometrics
Sir Francis GALTON 1822 - 1911
"grandfather" of modern psychology
Only ten years older than Wilhelm Wundt
yet his concepts started earlier and were fundamental for modern psychology.
Measurement of “immeasurable”
Prediction of “unpredictable
weather forecast
fingerprint
boredom
IQ and the career
correlation coefficient
comparative studies among relatives
word association, questionnaires
positive eugenics
Anthropometric Laboratory London 1884
The measurement of individual differences
PSYCHOMETRICS
Individual differences in skills, talents and personality traits
Pioneers: F. Galton 1884
A. Binet 1905 and
D. Wechsler 1934
F. Galton: The manifestations of intelligence in:
the speed and acuity
of sensory & motor responses.
Ph. Vernon 1987: speed of inspection & processing
Comparative studies and correlations
Scores versus real-life careers (questionnaires)
to validate the intelligence tests
“English man of science” 1874
- Correlating the scores from relatives (of various proximity)
to verify the heredity hypothesis
“Hereditary genius” 1869
- Statistics “Co-relations and their measurement –
chiefly from anthropological data” 1888
Statistical analysis “Co-relations and their measurement –
chiefly from anthropological data” 1888
Correlation coefficient
… and more contributions to modern psychology
The Word Association method
The recurrent associations
are not random,
they are meaningfully linked to
the forgotten past.
see later Freudian free association method
Jungian Word Association Test
Eugenics - a prototype of selective breeding
& genetic engineering
Negative eugenics: e.g., abortion of Down Syndrome fetus
Positive biological eugenics: promotion of extraordinarily
talented woman and man to marry
and to have gifted children
Non-biological “eugenics”: promotion and financial support for
talented people through:
stipends, grants, Dean's list, position
Nobel Prize and artistic awards
Criteria of intelligence
Francis Galton and later Phillip Vernon:
The fast processing of
information and fast response.
Intelligence depends on heredity.
Alfred Binet and later David Wechsler:
The logical and pragmatic reasoning.
Intelligence depends on experience (age).
Raymond Cattell: fluid vs. crystallized intelligence
Alfred Binet 1857 – 1911
A capacity for logical and pragmatic judgement.
Links to life experience
age group.
The tasks pre-tested on pupils grouped by their teacher as “typical for age,” “relatively retarded,” or “ relatively advanced"
- Correct performance of the set of tasks “typical-for-the-age”
as the indicator of Mental Age (MA) in the Binet-Simon Test
- The MA÷CA ratio is the indicator of intelligence, thus
MA = CA average e.g., MA 10 in a 10-year-old
MA > CA advanced e.g., MA 12 in a 10-year-old
MA < CA retarded e.g., MA 8 in a 10-year-old
* CA – chronological age
William Stern IQ = (MA ÷ CA) x 100. e.g., (12÷10) x 100 = 120
Louis Terman Stanford Univ. USA Stanford-Binet Scale
William Stern IQ = (MA ÷ CA) x 100. e.g., (12÷10) x 100 = 120
Louis Terman Stanford Univ. USA Stanford-Binet Scale
David Wechsler,
Bellevue Hospital, New York 1934
IQ scores in the population follow a normal distribution within different age groups.
2/3 of the population will have scores falling between the mean (M) plus or minus one standard deviation (SD)
If we assume that M = 100 and S.D. = 15, then 2/3 of the population would have an IQ between 85 and 115.
Wechsler Adult Intelligence Scale W.A.I.S. is designed for 16 – 74 years old
Wechsler Intelligence Scale for Children W.I.S.C. is for children.
W.A.I.S.
6 verbal scales: Comprehension, Vocabulary,
Information, Similarities, Arithmetics, Digit span
5 performance scales: Object assembly,
Block design, Picture completion,
Picture arrangement and Digit symbol.
Raw scores (within the age group)
converted into Scaled Scores 1-19.
The impact of schooling on the Binet and Wechsler test results
A remedy:
The Raven Matrices Test
An independent from the level of schooling test
A “culture-free” intelligence test
Charles Raven Matrices’ Test
A culture-free test measuring fluid intelligence (inborn talent independent from training and learning)
The subject has to figure out the rules by which the pattern changes from column to column and from row to row and then pick the pattern that belongs in the blank space from the set of eight choices.
Factor-analytical approach to the measurement of mental skills and traits
Factor analysis = a procedure for finding patterns of correlations among scores or tests to identify underlying factors (mental skills and traits).
Charles Spearman (1927) Purely mathematical definition of intelligence as a factor “g” – a general factor contributing to many intellectual specific abilities (s).
Charles Spearman (1927)
factorial theory of intelligence:
g = a general factor and s1 – sn = specific abilities
The factor g is a hypothetical factor that accounts for the positive
correlations among scores on different tests.
The s1, and s2 - specific abilities are required by a particular test,
e.g. spatial imagination
American authors:
L. Thurstone 1938 Seven primary abilities.
Ph. Vernon 1961 verbal vs. practical intelligence
The factors – reshuffled by Philip Vernon (1961)
G = general intelligence as a major factor for two sub-factors:
V = verbal abilities and
P = practical abilities
F. Galton’s theory of intelligence (acuity and speed of cognitive processes)
revisited and redefined by Ph. Vernon in terms of inspection time needed to detect essential relationships between stimuli
Raymond Cattell:
- fluid intelligence = inborn predisposition or talent; manifests itself in logical thinking
- crystallized intelligence = a skill based on the learning and training