Galton: statistical analysis as applied to mental and behavioral phenomena.
"The only information that reaches us concerning outward events appears to pass through the avenues of our senses; and the more perceptive the senses are of difference, the larger is the field upon which our judgement and intelligence can act."
- believed that a person's reputation could be used to measure ability
- ... that hereditary plays an important role in intelligence
- studied several prominent men of his time concluded that intelligence was hereditary
- the higher one's intelligence, the higher one's level of sensory discrimination (derived from John Locke's empiricist assumption that all knowledge came through the senses)
- "the most capable individuals have the most acute senses... lowest grade of idiots often have sensory deficits seemed to confirm this line of thinking" (Loevinger, 1987, p. 98)
- set up an Anthropometric Laboratory in 1884 at an International Health Exhibition (ane he is believed to be the only psychologist to be paid by the experimentees)
- pre-dated current physiological research on speed of neural conductivity and intelligence
- One of the first to employ questionnaire and survey methods, to investigate mental imagery in different groups.
Piaget: Stages of Mental Growth in Children
"The child can grasp a certain operation only if he is capable, at the same time, of correlating operations by modifying them in different well-determined ways for instance, by inverting them."
- distinguished four stages to the mental growth of children
- sensorimotor stage (birth to age 2) child is concerned with gaining motor control and learning about physical objects - develops object permanence
- preoperational stage (2 to 7) child is preoccupied with verbal skills. At this point the child can name objects and reason intuitively
- concrete operational stage (7 to 12) begins to deal with abstract concepts such as numbers and relationships - conservation
- formal operational stage (12 to 15) the child begins to reason logically and systematically.
- Piaget's 2 Mental Operations
- Assimilation: actively organizing new information so that it fits in with what already is perceived and thought.
- Accommodation: changing already perceived thoughts to fit in with new information.
Binet: the first major "Test of Intelligence"
"The scale, properly speaking, does not permit the measure of the intelligence, because intellectual qualities are not superposable, and therefore cannot be measured as linear surfaces are measured" (Gould, p.181)."
- Associationism - the operations of intelligence were nothing more than diverse forms of the laws of association
- argued that what ever intelligence was, it could never be isolated from the true experiences, circumstances, and personal associations of the individual.
- developed and tried all kinds of tests and puzzles out on his own daughters
- began to discover the importance of attention span on the development of adult intelligence.
- studied the effect of suggestibility in experiments with children
- New universal education laws required that all French children be given an education, and the subject of mental retardation aroused much official interest
- Binet and Simon (his grad student) attempted to develop a test that would roughly estimate intelligence
- developed a series of exercises called "mental orthopedics" to raise not only the intellectual levels but also the actual intelligence of retarded children.
Spearman: Two-Factor Theory of Intelligence "g" & "s"
- completed his Ph.D. under Wilhelm Wundt, but was also influenced by the works of Francis Galton and his case for the importance of intelligence testing
- set out to estimate the intelligence of twenty-four children in the village school
- realized that any empirically observed correlation between two variables will underestimate the "true" degree of relationship
- if inaccuracy or unreliability in the measurement of those two variables is precisely known, it is possible to "correct" the attenuated observed correlation
- r (true) = r (observed) /reliability of variable 1 X reliability of variable 2
- found "perfect" relationships and inferred that "General Intelligence" or "g" was in fact something real
- two-factor theory of intelligence: performance of any intellectual act requires some combination of
- "general factors" "g", which is available to the same individual to the same degree for all intellectual acts
- "specific factors" or "s" which are specific to that act and which varies in strength from one act to another
- If you know how a person performs on one task that relies on "g", you can predict a similar level of performance for a another highly "g" saturated task.
- Prediction of performance on tasks with high "s" factors are less accurate.
Cattell: Fluid and Crystallized Intelligence
Cattell gave special significance to issues of cultural bias in mental testing, and outlined his Two Factor Theory of Intelligence:
- Fluid Intelligence - non-verbal relatively culture free, independent of specific instruction (i.e. memory of digits).
- Crystallized Intelligence - acquired skills and knowledge that are dependant on exposure to a culture as well as to formal and informal education (i.e. vocabulary).
Thurstone: Primary Mental Abilities
Believed intelligence to be a composition of distinct abilities known as Primary Mental Abilities (PMA's), made up of:
- verbal meaning.
- perceptual speed.
- number facility.
- role memory.
- word fluency.
- spatial relations.
E. L. Thorndike: Multifactor Theory
Defined intelligence as a large number of interconnected intellectual elements representing a distinct ability, known as the Multifactor Theory, with 3 clusters of intelligence:
- social: deals with people.
- concrete: deals with objects.
- abstract: deals with verbal & mathematical symbols.
Terman: Identification of gifted children
Followed 1,528 children whose IQ score was above 140.
- Gifted tended to maintain their superior ability.
- Lower mortality rates.
- Maintained better physical and mental health.
- Held moderate political views.
- Successful in educational and vocational pursuits.
- Committed less crime.
Wechsler: Grandfather of Intelligence Testing
Intelligence is an aspect of the total personality, rather than an isolated entity.
- administered and interpreted exams developed for use in assigning army recruits to military jobs suited for them
- noted a discrepancy between the intellectual abilities in civilian life and performance on the mental tests used to judge soldiers
- Spearman's two factor theory of 'g' and many s's to be simplistic
- "the global capacity to act purposefully, to think rationally, and to deal effectively with his environment"
- introduced the Deviation Quotient, computed by the individual's mental ability in comparison with the norm group.