Chapter 9

Intelligence

Defining Intelligence

• Intelligence: global capacity to act purposefully, think rationally, and deal effectively with the environment

• g-factor: general ability factor, or core of general intelligence that involves reasoning, problem-solving ability, knowledge, memory, and successful adaptation to one’s surroundings

• Operational definition: operations used to measure a concept; in the case of intelligence, creating an intelligence test

Aptitudes

• Aptitude: capacity for learning certain abilities• Special aptitude test: test that predicts whether

you will succeed in a single area• Multiple aptitude test: test that measures two or

more types of ability• General intelligence test: test that assesses a

wide variety of mental abilities

Reliability and Validity

• Psychometric test: any measurement of a person’s mental functions

• Reliability: a reliable psychometric test must give approximately the same score each time a person takes it

• Validity: a valid psychometric should measure what it claims to measure

Objective Testing

• Objective test: a test (IQ or otherwise) is objective if it gives the same score when corrected by different people

• Test standardization: first, it means standard procedures are used in giving the test and, second, individual test scores are compared to norms, or average scores made by a large group of people like those for whom the test was designed

Testing Intelligence: The Stanford-Binet

• Stanford-Binet Intelligence Scale, Fifth Edition (SB5): widely used individual intelligence test, derived directly from Alfred Binet’s first intelligence test; items are age-ranked

SB5: Five Cognitive Factors

• Fluid reasoning• Knowledge• Quantitative reasoning• Visual-spatial processing• Working memory

Wechsler Tests

• Wechsler Adult Intelligence Test, 4th Edition (WAIS-IV)

• Wechsler Intelligence Scale for Children, 4th Edition (WISC-IV)

• Like the SB-5, the Wechsler tests yield– a single overall intelligence score– a separate score for performance (nonverbal)

intelligence– a separate score for verbal (language- or

symbol-oriented) intelligence.

Group Tests

• Individual intelligence test: designed to be given to a single person by a trained specialist (e.g., SB5 and the Wechsler tests)

• Group intelligence tests can be given to a large group of people with minimal supervision (e.g., Army Alpha, SAT Reasoning Test, American College Test, (ACT), College Qualification Test (CQT))

Intelligence Quotient (IQ)

• Mental age: average intellectual performance• Chronological age: person’s age in years• Intelligence index: mental age divided by

chronological age, then multiplied by 100– Average IQ in the USA is 100

• Deviation IQ: scores based on a person’s relative standing in his or her age group; how far above or below average a person’s score is, relative to other scores

Stability of IQ

• IQ scores are not dependable until a child reaches age 6

• After age 6, IQ scores become more stable• Fluid intelligence: solving novel problems

involving perceptual speed or rapid insight; declines rapidly after middle age

• Crystallized intelligence: solving problems using already acquired knowledge—can actually increase or at least decline very little until advanced age

Other Variations in IQ

• Normal (bell-shaped) curve: distribution of observed IQ scores; most scores fall close to the average, and very few are found at the extremes

• Men and women do not appear to differ in overall intelligence

• A strong correlation (about .50) exists between IQ and school grades

Gifted Children

• Have a high IQ (usually above 130) or special talents or abilities (play Mozart at age 5)

• Gifted or not, successful people are persistent and motivated to learn

Intellectual Disability

• An IQ score below 70 and a significant impairment of adaptive behavior together define intellectual disability– Adaptive behavior: basic skills such as

dressing, eating, working, hygiene; necessary for self-care

Causes of Intellectual Disability

• Familial intellectual disability: mild intellectual disability that occurs in homes that have inadequate nutrition, intellectual stimulation, medical care, and emotional support; accounts for 30-40% of cases

• Organic intellectual disability: intellectual disability related to physical disorders

Organic (Physical) Causes of Intellectual Disabilities

• Birth injuries: lack of oxygen during delivery• Fetal damage: prenatal damage from disease,

infection, or drug use • Metabolic disorders: affect energy use and

production in the body• Genetic abnormalities: missing genes, extra

genes, or defective genes

Down Syndrome (Trisomy 21)

• Most common form of genetic intellectual disability; occurs In 1/800 babies

• Down syndrome children have an extra 21st chromosome; genetic problem but not hereditary

• Reproductive cells of older parents more prone to errors during cell division

• Down children are usually loving and responsive

Fragile X Syndrome

• Second most common form of genetic intellectual disability; occurs In 1/3,800 boys

• Fragile X is hereditary; sex-linked to x-chromosome and affects boys more often

• Fragile X males generally have long, thin faces and big ears and suffer from hyperactivity and attention disorders

• They are only mildly intellectually disabled during early childhood, severely intellectually disabled as adults

Phenylketonuria (PKU)

• Genetic disease involving lack of an important enzyme, causing buildup of phenylpyruvic acid (a destructive chemical)– Untreated, it leads to severe intellectual

disability by age 3

Microcephaly (“Smallheadedness”)

• A rare abnormality in which the skull is extremely small or fails to grow– Forces brain to develop in a limited space,

causing severe intellectual disability

Hydrocephaly (“Water on the Brain”)

• Pressure from excess buildup of cerebrospinal fluid within brain cavities damages brain and enlarges the head– Tube can be implanted to drain fluid from the

brain to the stomach and minimize brain damage

Cretinism

• Due to an insufficient supply of thyroid hormone– Untreated, will cause stunted physical and

intellectual growth– Can be treated with thyroid hormone

replacement before permanent damage occurs

Heredity and Environment: Hereditary Influences

• Eugenics: selective breeding for desirable characteristics– Suggests that some traits are highly

influenced by heredity

Twin Studies

• Comparison of characteristics of twins who were raised together or separated at birth; used to identify relative impact of heredity and environment– IQs of identical twins (twins who develop from

a single egg and have identical genes) are more similar than IQs of fraternal twins (two separate eggs fertilized at the same time)

Heredity and Environment: Environmental Influences

• Children from high socioeconomic status (SES) homes develop higher IQs

• Children adopted out of low SES homes experience IQ gains

• Flynn effect: dramatic IQ gains made by Western industrialized nations over the last 30 years

• Early childhood education programs produce long-term gains in IQ

Heredity and Environment: Conclusion

• Most researchers believe that intelligence is a combination of heredity (genes) and environment (upbringing)– Degree of contribution of each is not known

yet

The Intelligent Nervous System

• People with higher IQs perform faster on reaction time tasks– Reaction time: the time it takes people to

respond to a stimulus– Speed of processing: measured with reaction

time, which is assumed to reflect the brain’s speed and efficiency

The Intelligent Nervous System (cont’d)

– Parts of frontal cortex are larger in people with higher IQs

– The same is true for other parts of cortex

Intelligent Information Processing (Perkins)

• Three factors determining intelligence– Neural intelligence: speed and efficiency of

the nervous system– Experiential intelligence: specialized

knowledge and skills acquired over time– Reflective intelligence: ability to become

aware of one’s own thinking habits• Metacognitive skills: the ability to manage your

own thinking and problem-solving

Artificial Intelligence (AI)

• Artificial intelligence (AI): computer programs that perform humanlike problem-solving or intelligent responding

• Computer simulations: programs that attempt to duplicate human behavior, especially thinking, problem-solving, or decision-making

• Expert systems: computer programs that respond as a human expert would

Multiple Intelligences: Howard Gardner

• Multiple intelligences: theory posed by Howard Gardner that states we have several specialized types of intellectual ability

Gardner’s Theory of Eight Multiple Intelligences

• Language: linguistic abilities; used by writers, lawyers, comedians

• Logic and math: numeric abilities; used by scientists, accountants, programmers

• Visual and spatial: pictorial abilities; used by engineers, inventors, artists

• Music: musical abilities; used by composers, musicians, music critics

Gardner’s Theory of Eight Multiple Intelligences (cont’d)

• Bodily-kinesthetic: physical abilities; used by dancers, athletes, surgeons

• Intrapersonal: self-knowledge; used by poets, actors, ministers

• Interpersonal: social abilities; used by psychologists, teachers, politicians

• Naturalistic: ability to understand natural environment; used by biologists, medicine men, organic farmers

Intelligent Intelligence Testing

• Culture-fair test: test designed to minimize importance of skills and knowledge that may be more common in some cultures than in others

IQ and Race

• Historically, African Americans scored lower on IQ tests than European Americans

• Asian Americans scored higher than European Americans

• Attempts to explain in genetic terms have been criticized

IQ and Race (cont’d)

• Standard IQ tests do not always allow meaningful comparisons between ethnic, cultural, or racial groups

• African Americans are more likely than European Americans to live in impoverished environments

• “Race” is a concept that makes no genetic sense; external markers, like skin color, have little to do with underlying genetic differences

Wisdom

• Intelligence reflects development as well as potential, nurture as well as nature

• People can be intelligent without being wise• Wisdom represents a mixture of convergent

thinking, intelligence, and reason, spiced with creativity and originality

• People who are wise approach life with openness and tolerance