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Chapter 11

Intelligence

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Defining IntelligenceGlobal capacity to act purposefully, think rationally, and deal effectively with the environmentOperational Definition: Operations used to measure a conceptAptitude: Capacity for learning certain abilitiesMultiple Aptitude Test: Test that measures two or more abilitiesGeneral Intelligence Test: Test that measures a wide variety of mental abilities

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Fig. 11.1 Special aptitude tests measure a person’s potential for achievement in a limited area of ability, such as manual dexterity. Multiple aptitude tests measure potentials in broader areas, such as college work, law or medicine. Intelligence tests measure a very wide array of aptitudes and mental abilities

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Fig.11.2 Sample questions like those found on tests of mechanical aptitude. (The answers are A and the Driver.)

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Reliability

Reliability: A measure should give the same score each time the same person takes it

Test-Retest: Give test to a large group, then give exactly the same test to same group later

Split-Half: Making sure scores on one-half of a test match the scores on the other half

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Validity

Validity: Ability of a test to measure what it is purported to measureCriterion Validity: Comparing test scores to

actual performance Comparing SAT to college grades

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Testing Intelligence

Norm: Average score for a designated group of people

Stanford-Binet Intelligence Scale, Fifth Edition (SB5): Widely used individual intelligence test, derived directly from Alfred Binet’s first intelligence test; for ages 2-90!

Chronological Age: Person’s age in years

Mental Age: Average intellectual performance

Intelligence Quotient (IQ): Intelligence index; mental age divided by chronological age, then multiplied by 100 Average IQ in the USA is 100

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Fig.11.4 The stability or reliability of IQ scores increases rapidly in early childhood. Scores are very consistent from early adulthood to later middle age. (Source: Schuerger & Witt, 1989.)

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More IQ Terms

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

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

Terminal Decline: Abrupt decline in measured IQ about 5 years before death

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Wechsler Tests

Wechsler Adult Intelligence Test-Third Edition (WAIS-III): Adult intelligence test that rates verbal and performance intelligence and abilities Wechsler Intelligence Scale for Children-Third

Edition (WISC-III): Downscaled version of the WAIS-III; for children aged 6 years to 16 years 11 months, 30 days

SB5 is better suited for children and adolescents WISC-IV to be published in 2003

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Wechsler Scales

Performance Intelligence: Nonverbal intelligence; measured by solving puzzles, completing pictures, and assembling objects

Verbal Intelligence: Language intelligence; measured by answering questions involving vocabulary, information, arithmetic, and other language-oriented tasks

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Group Tests

These tests can be given to a large group of people with little supervision; usually contain multiple-choice itemsArmy Alpha was the first group intelligence

test; developed for those entering World War I in the USA

Normal (Bell-Shaped) Curve: Most scores fall close to the average, and very few are found at the extremes

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IQ Research

Men and women do not appear to differ in overall intelligence

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

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Giftedness

Having a high IQ (usually above 130) or special talents or abilities (playing Mozart at age 5)

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Mental Retardation (or Developmental Disabilities): Some Definitions

Presence of a developmental disability and an IQ score below 70; a significant impairment of adaptive behavior also figures into the definition Adaptive Behavior: Basic skills such as dressing,

eating, working, hygiene; necessary for self-care

Familial Retardation: Mild mental retardation that occurs in homes that have inadequate nutrition, intellectual stimulation, medical care, and emotional support

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Organic Causes of Mental Retardation

Related to physical disordersBirth Injuries: Lack of oxygen during deliveryFetal Damage: Congenital problem; prenatal damage from disease, infection, or drug use by the motherMetabolic Disorders: Disorder in metabolism; affects energy use and production in the bodyGenetic Abnormalities: Abnormality in the genes, such as missing genes, extra genes, or defective genes

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Types of Organic Causes

Phenylketonuria (PKU): Genetic disease in which the child lacks an important enzyme. Allows phenylpyruvic acid to accumulate in the body If untreated, severe retardation may occur by age 3 Routine medical tests at birth can detect PKU Treat with phenylalanine-free diet (found, for

example, in Aspartame, known as Nutrasweet)

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More Organic Causes of Mental Retardation

Microcephaly: Head and brain are abnormally small; brain is forced to develop in a limited spaceHydrocephaly: Buildup of cerebrospinal fluid within the ventricles (brain cavities); pressure can enlarge the head and damage the brainCretinism: Stunted growth and retardation caused by insufficient supply of thyroid hormone May also be caused by lack of iodine Easily detected in infancy

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Down Syndrome

Down Syndrome: Genetic disorder caused by presence of extra chromosome (usually on the 21st pair; trisomy 21); results in mental retardation and shorter life span Does not run in the family Older a woman is, greater the risk to produce a

Down’s child Older fathers also contribute (about 25% of the

time) No cure, but is detectable before birth

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Fragile X Syndrome

Fragile X Syndrome: Genetic form of retardation caused by defect in X chromosomeRuns in familiesSex-linked; mainly affects boysMost suffer from hyperactivity and attention

disordersBecome more severely retarded as adults

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Heredity and Environment

Eugenics: Selective Breeding for desirable characteristicsFraternal Twins: Twins conceived from two separate eggsIdentical twins: Twins who develop from a single egg and have identical genesMany researchers believe that intelligence is a combination of heredity (genes) and environment (upbringing); contributing percentage of each is not known yet

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New Ways of Viewing Intelligence

Speed of Processing: Brain’s speed and efficiency; how fast you and your brain can process informationInspection Time: Amount of time a person must look at a stimulus to make a correct judgment about itNeural Intelligence: Speed and efficiency of the nervous system; innateExperiential Intelligence: Specialized knowledge and skills acquired over time

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Fig.11.8 Attempts to measure the speed of mental processing have taken several forms. In this example, the person must make a rapid choice based on the position of a colored stimulus flashed on the computer screen. A faster reaction time is assumed to reflect faster processing of information. In some experiments, brain responses are measured directly, through electrodes attached to the scalp.

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Fig.11.9 Stimuli like those used in inspection time tasks.

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New Ways of Viewing Intelligence (cont.)

Reflective Intelligence: Ability to become aware of one’s own thinking habits

Metacognitive Skills: Ability to manage one’s own thinking and problem solving efforts

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Gardner’s Theory of Intelligence: Some Concepts

Multiple Intelligences: Theory posed by Howard Gardner that states we have several specialized types of intellectual ability

G-Factor: General ability factor; assumed to explain the high correlations among various intellectual measures

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Gardner’s Theory of Eight Multiple Intelligences

Language: Used for thinking by lawyers, writers, comediansLogic and Math: Used by scientists, accountants, programmersVisual and Spatial Thinking: Used by engineers, inventors, aviatorsMusic: Used by composers, musicians, music critics

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

Bodily-Kinesthetic Skills: Used by dancers, athletes, surgeonsIntrapersonal Skills (Self-Knowledge): Used by poets, actors, ministersInterpersonal Skills (Social Abilities): Used by psychologists, teachers, politiciansNaturalistic Skills (Ability to Understand Natural Environment): Used by biologists, organic farmers

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A Different Type of Intelligence Test

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

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Fig.11.10 No intelligence test can be entirely free of cultural bias. However, culture-fair intelligences test try to minimize the effects of growing up in various cultures. The following sample items are from a culture-fair test. 1. Which pattern is different from the remaining four? (Number 3.) 2. Which of the five figures on the right would properly continue the three on the left_that is, fill in the blank? (Number 5.) 3. Which of the figures on the right should go in the square on the left to make it look right? (Number 2.) 4. At left, the dot is outside the square and inside the circle. In which of the figures on the right could you put a dot outside the square and inside the circle? (Number 3) (Courtesy of R.B. Cattell).