INTELLIGENCEINTELLIGENCE

Chapter 8

What is IntelligenceWhat is Intelligence??Typical Definitions1.mental abilities needed to select, adapt to, and shape environments

2. abilities to: – profit from experience– solve problems– reason effectively– meet challenges and achieve goals

–Formal definition proves elusive.

Is intelligence a single reasoning Is intelligence a single reasoning ability?ability?

• Charles Spearman’s g-factor (general intelligence)– Speed of mental processing

• Separate reasoning skills – Robert Sternberg– Analytical, practical, creative (Triarchic)

• Multiple abilities – Howard Gardner– Linguistic, mathematical, musical, kinesthetic,

intrapersonal, interpersonal, spatial, naturalist

Origins of IQ ScoreOrigins of IQ Score

• (MA/CA) x 100

• MA = Mental Age– a measure of intelligence test performance

devised by Binet where a given level of test performance is represented by the average age of children who perform at that level.

– (For example, a child who does as well as the average 8-year-old is said to have a mental age of 8.)

• CA = Chronological Age, or the age of the test taker

Intelligence TestsIntelligence Tests• Most popular – Wechsler 1939• WAIS-IV – adults

– Wechsler Adult Intelligence Scale• WISC-IV – children

– Weschler Intelligence Scale for Children• WPPSI-III - preschoolers

– Wechsler Preschool & Primary Scale of Intelligence

• Stanford - Binet

Assessing IntelligenceAssessing Intelligence– Standardization– Today meaningful IQ scores are defined by

comparison with the performance of a pretested “standardization group”

– Normal Curve – the symmetrical bell-shaped curve that

describes the distribution of many physical and psychological attributes including IQ

– most scores fall near the average; fewer and fewer scores lie near the extremes

The Normal CurveThe Normal Curve

Ninety-five percent of all people fall within 30 points

of 100

Number of

scores

55 70 85 100 115 130 145 Wechsler intelligence score

Sixty-eight percentof people score within 15 points

above or below 100

Is intelligence inherited?Is intelligence inherited?• Partially – This is a nature-nurture

question.

• Are differences in ethnic group averages hereditary?– No. this is best explained culturally.

Plant-Pot AnalogyPlant-Pot Analogy

Early InterventionsEarly Interventions• High-quality center-based interventions

improve intelligence & school achievement

– Effects strongest for poor children with uneducated parents

– Positive effects linger into adolescence, but get smaller

– Effects best sustained where programs continue into middle school

Tests of Infant IntelligenceTests of Infant Intelligence

• Less verbal, more perceptual-motor

• Do not correlate well with later measures of IQ

• Often called DQ (Developmental Quotient)

Tests of Infant IntelligenceTests of Infant Intelligence

• Gesell (1934) detect abnormal infants for adoption agencies– Motor, language, adapative, personal-

social

• Bayley Scales of Infant Development (1969)– Mental, motor & behavior measures– Diagnose developmental delays 1 to 42

mos.

FaganFagan Test of Infant Intelligence Test of Infant Intelligence (1992)(1992)

• Encoding attributes

• Detecting similarities & differences among objects

• Forming mental representations

• Retrieving mental representations

FaganFagan Test of Infant Intelligence Test of Infant Intelligence (1992)(1992)

• Works well across cultures

• Predicts intelligence in childhood & adolescence

• Quicker habituation & more looking in dishabituation reflects more effective information processing.

Stability of IntelligenceStability of Intelligence

• Using groups of different ages (6, 8, 10, & 18), get high correlations (+.70 - +.90) across ages 2-18

• One study testing the same children between the ages of 2 ½ & 17 found changes of up to 40 points in one-third of them (average range = 28 points)

Intelligence in AdulthoodIntelligence in Adulthood

• Horne (1980s)• Cross sectional• Groups differed in educational

opportunities• Problem of cohort effects• Found fluid intelligence to decline;

crystallized intelligence not to

Changes in Mental Abilities Changes in Mental Abilities in Adulthoodin Adulthood

• Crystallized intelligence: skills that use accumulated knowledge & experience, good judgment & mastery of social conventions.

– IQ test: vocabulary, general information, logical reasoning, verbal analogy

– These skills maintain or increase.

Changes in Mental Abilities Changes in Mental Abilities in Adulthoodin Adulthood

Fluid intelligence: detecting relationships among stimuli, speed of processing, working memory; abstract reasoning

– IQ test: number series, spatial visualization, picture sequencing

– These skills decline from middle adulthood.

The Seattle Longitudinal The Seattle Longitudinal StudyStudy

• Midlife is a period of peak performance on 5 abilities..

• Vocabulary• Verbal memory• Number• Spatial orientation• Inductive reasoning

• Perceptual speed drops from the 20s

K. Werner Schaie

Changes in IQ Test Changes in IQ Test Performance in AdulthoodPerformance in Adulthood

• Cognitive mechanics: neurological hardware of the brain; affected by biology & health; prone to decline with age

• Cognitive pragmatics: skills, comprehension; cultural experience; may improve with age

Paul Baltes (1990s; 2000s)

Changes in IQ Test Changes in IQ Test PerformancePerformance

• Many studies show that crystallized intelligence increases, fluid processing speed declines.

• General Conclusion: Declines are due to a general slowing of the Central Nervous System.

• There are large individual differences.

Use It or Lose ItUse It or Lose It

Factors correlating with less decline, better performance on cognitive tests:

above-average educationhighly complex occupationsstimulating leisure pursuits

better social situationabsence of disease