PSY 250 Lecture Notes - Lecture 55: Methylphenidate, Ventricular System, Information Processing
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Chapter 13: Intelligence and Cognitive Functioning Book Notes
A. Introduction Information
a. People call Stephen Hawking the most brilliant person living today
b. He has developed theories of the origin of the universe that are altering the way scientists think
c. He lectures around the world, mixing high-powered physics with a keen sense of humor
d. He has Lou Gehrig’s Disease (Amyotrophic Lateral Sclerosis [ALS])
i. Degenerative disease that impairs voluntary movement
ii. Confined to a wheelchair, makes small facial movements, writes and speaks by moving a cursor on the
screen of a computer equipped with a voice synthesizer
B. The Nature of Intelligence
a. Intelligence: the ability to reason, to understand, and to profit from experience
b. We do not completely know what intelligence is
c. What Does “Intelligence” Mean?
i. Intelligence Quotient (IQ): the measure of intelligence is typically expressed as this
ii. Term originated with the scoring on early intelligence tests designed for used with children
iii. Tests produced a score in the form of a mental age, which was divided by the child’s chronological age and
multiplied by 100
iv. Tests were designed to produce a score of 100 for a child performing at the average fro his or her
chronological age
v. Scoring is different now because scoring has been extended to adults
vi. Most people are near the average (only 2% of the population score above 130 points or below 70 points)
vii. Alfred Binet created the first intelligence test
viii. IQ is related to school performance, job performance, income, socioeconomic level, and negatively,
juvenile delinquency
ix. Sternberg argues that intelligence doesn’t exist in the sense we usually conceive of it but is “a cultural
invention to account for the fact that some people are able to succeed in their environment better than
others”
d. The Structure of Intelligence
i. Another controversy that is critical to biological understanding of intelligence is whether intelligence is a
single capability or a collection of several independent abilities
ii. Intelligence theorists fall into two groups
1. Lumpers
a. Claim that intelligence is a single, unitary capability, which is usually called the general
factor, or simply g
b. General factor theorists admit that there are separate abilities that vary somewhat in
strength in an individual, but they place much greater weight on the underlying g factor
c. Point out that a person who is high in one cognitive skill is usually high in others
d. Believe that a measure of g is adequate by itself to describe a person’s intellectual ability
e. General intelligence is assessed by overall IQ score from a traditional intelligence test
(Wechsler Adult Intelligence Scale) whose 11 subjects measure more specific abilities
f. Prefer to use other tests (Raven Progressive Matrices) because they emphasize reasoning
and problem solving and are relatively freer from specific abilities such as verbal skills
2. Splitters
a. Hold that intelligence is made up of several mental abilities that are more or less
independent of each other
b. They are more interested in scores on the subtests of standard IQ tests or scores from tests
of specific cognitive abilities
c. May agree that there is a general factor, but they give more emphasis to separate abilities
and to differences among them in an individual
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d. An accurate description of a person’s intelligence would require the scores on all the
subtests of these abilities
e. Point to cases of brain damage in which one capability is impaired without affecting
others and to the savant’s exceptional abilities there are
f. A review of intelligence tests identified more than 70 different abilities that can be
measured by available tests
C. The Biological Origins of Intelligence
a. Avoiding two popular assumptions
i. Intelligence tests are the only way to define intelligence
ii. Intelligence is a single entity
b. Consider performance and achievement as additional indicators of intelligence
c. The Brain and Intelligence
i. Albert Einstein’s brain was preserved to be examined again and again by neuroscientists
ii. His brain was almost 200 g lighter than the average weight of a normal brain, the number of neurons did
not differ from normal, and studies have disagreed about whether neurons were more densely packed or the
cortex was thinner
iii. One study found a higher ratio of glial cells to neurons in the left parietal lobe
iv. Each of Einstein’s hemispheres were a full centimeter wider than those of a normal brain
v. Researchers scanned brains of 241 individuals with brain damage and correlated location of their lesions
with their scores on a set of intelligence subtests chosen to measure g
1. Found that g requires a distributed system, a network that spans the frontal, parietal, and temporal
lobes
2. Concluded that g involves brain’s ability to pull together different kinds of processing
a. Visual-spatial processing
b. Working memory
3. Ability to integrate these functions depends on quality of connections between areas, which is
highly heritable, up to 84% in some parts of brain
vi. Brain Size
1. Brain size itself does not determine intelligence
2. What is more important is ratio of brain’s size to body size (this ratio adjusts for proportion of
brain needed for managing body and tells us how much is left over for intellectual functions
3. Many MRI studies have found correlations between brain size and measures of intelligence
a. A compilation of 37 studies involving 1,530 people found a modest correlation of 0.33
b. Squaring the correlation coefficient tells us that about 11% of the differences among
people in intelligence is related to brain size
4. Men have larger brains than women, which we have assumed was related to men’s greater body
size (men’s brains are on average 118 g heavier than women’s)
5. Men are no smarter than women (difficult to tell because intelligence tests were designed to avoid
gender bias)
6. There are 2 hypothesis as to what the extra brain matter functions as in men’s brains
a. Women’s brains are more efficient, because of a greater density of neurons and a higher
ratio of gray matter to white matter
b. Male’s superior spatial intelligence requires greater brain capacity
7. MRI studies of fraternal and identical twins found that general intelligence was correlated with
both volume of gray matter and volume of white matter
8. Volume of gray matter and frontal area appears to be particularly important to general intelligence
9. How the brain matter is distributed and organized appears to be more important than size
10. Computer modeling has shown that smaller columns provide for better discrimination between
signals during information processing
11. General intelligence is moderately correlated with cortical thickness in most association areas
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vii. Neural Conduction Speed and Processing Speed
1. Cognitive process require person to apprehend, select, and attend to meaningful items from a
welter of stimuli arriving at sensory organs
2. Person must retrieve information from memory, relate new information to it, and then manipulate
mental representation of combined information
3. Francis Galton suggested that higher intelligence depends on greater “mental speed”
a. Attempted to relate measures of intellectual achievement like course grades and
occupational status to people’s reaction times, but no relationship was found
4. A number of researchers have shown that IQ scores do correlate with reaction time
a. Relationship isn’t due to fact that most intelligence tests emphasize speed, because
reaction time and IQ scores are still correlated when IQ test is given without a time limit
5. IQ scores are also correlated with nerve conduction velocity, even more than with reaction time
6. People who are more intelligent excel on task in which stimuli are presented for an extremely
short interval and on tasks that require choices
viii. Processing Efficiency
1. Intelligence comes down to how well information travels throughout the brain
2. One of the most obvious contributors to this efficiency is myelination (increases conduction speed
and protects against “cross-talk” between neurons)
3. Humans have a greater proportion of white matter (myelinated processes) to gray matter than other
animals, and IQ varies among individuals with the degree of myelination
4. One indicator of role of brain efficiency in intelligence is that individuals who are higher in IQ use
less brain energy (indicated by a lower rate of glucose metabolism during a challenging task
[playing Tetris])
5. After reviewing 37 imaging studies related to intelligence, Rex Jung and Richard Haier proposed
the Parieto-Frontal Integration Theory (P-FIT)
a. Information processing takes place in four stages in parietal and frontal lobes
i. After sensory information has been processed in secondary areas, it is passed
onto
ii. Parietal areas, which abstract the information and integrate it, and then
iii. These areas interact with frontal areas in problem solving and evaluation
iv. Finally, the anterior cingulate cortex selects the response and inhibits alternative
responses
b. Studies have lent support to the theory, identifying these areas as central to intelligence
and the parietal cortex as the main hub
c. The brains of more intelligent individuals were more efficient, with more numerous
interconnections within clusters of neural activity and shorter paths between clusters
d. Specific Abilities and the Brain
i. Brain size, speed, and efficiency can reasonably be viewed as contributors to general intelligence
ii. Factor analysis has been useful in identifying possible components
1. Procedure involves giving a group of people several tests that measure cognitive abilities that
might be related to intelligence
2. Tests may be intelligence tests, or they may be measures of more limited abilities such as verbal
skills or reaction time
3. Correlations are calculated among all combinations of the tests to locate “clusters” of abilities that
are more closely related with each other than with the others
iii. Three capabilities have emerged frequently as major components of intelligence
1. Linguistic
2. Logical-Mathematical
3. Spatial
iv. Some people believe that the brain is hardwired for functions like mathematics and language
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Document Summary
Confined to a wheelchair, makes small facial movements, writes and speaks by moving a cursor on the screen of a computer equipped with a voice synthesizer: the nature of intelligence. Intelligence: the ability to reason, to understand, and to profit from experience: we do not completely know what intelligence is, what does intelligence mean? ix. Intelligence quotient (iq): the measure of intelligence is typically expressed as this. Term originated with the scoring on early intelligence tests designed for used with children. Tests produced a score in the form of a mental age, which was divided by the child"s chronological age and multiplied by 100. Tests were designed to produce a score of 100 for a child performing at the average fro his or her chronological age. Scoring is different now because scoring has been extended to adults: most people are near the average (only 2% of the population score above 130 points or below 70 points)
