Assessment of Assessment of IntelligenceIntelligence

General Definitions of General Definitions of IntelligenceIntelligence

►Capacity to learn.Capacity to learn.►Ability to solve abstract & novel Ability to solve abstract & novel

problems.problems.►Ability to understand complex ideas.Ability to understand complex ideas.►General knowledge of one’s culture.General knowledge of one’s culture.►Adaptation to environment.Adaptation to environment.►Social judgment.Social judgment.

E.G. Boring’s DefinitionE.G. Boring’s Definition

► Intelligence represents “whatever is Intelligence represents “whatever is measured by an intelligence test.”measured by an intelligence test.”

Purposes of Intellectual Purposes of Intellectual Assessment:Assessment:

►Psychoeducational Assessment: Psychoeducational Assessment: identification & placement of special-needs identification & placement of special-needs students. students.

►Predict academic and work performance.Predict academic and work performance.►Evaluate for Mental Retardation & Learning Evaluate for Mental Retardation & Learning

Disabilities.Disabilities.►Evaluate for neurological impairment.Evaluate for neurological impairment.►Career Counseling.Career Counseling.►Research.Research.

History of Intelligence History of Intelligence TestingTesting

► Charles Darwin’s theory of evolution sparked interest Charles Darwin’s theory of evolution sparked interest in the study of differences in mental abilities.in the study of differences in mental abilities.

► Francis Galton, cousin of Charles Darwin, studied Francis Galton, cousin of Charles Darwin, studied family trees to try to demonstrate a hereditary basis family trees to try to demonstrate a hereditary basis for intelligence.for intelligence.

► Early intelligence tests measured sensorimotor Early intelligence tests measured sensorimotor functions, such as reaction time.functions, such as reaction time.

► 1905: Alfred Binet & Theodore Simon developed a test 1905: Alfred Binet & Theodore Simon developed a test to identify mentally retarded students in Paris, France.to identify mentally retarded students in Paris, France.

► 1916: Lewis Terman published the first version of the 1916: Lewis Terman published the first version of the Stanford-Binet Intelligence Scale.Stanford-Binet Intelligence Scale.

► 1939: David Wechsler published the Wechsler-Bellevue 1939: David Wechsler published the Wechsler-Bellevue Scale.Scale.

Study of Intelligence: Two Study of Intelligence: Two EmphasesEmphases

►Theoretical CampTheoretical Camp: What is the true : What is the true nature of intelligence? What nature of intelligence? What components or processes are components or processes are responsible for intelligent behavior? responsible for intelligent behavior? Focus on Construct Validity.Focus on Construct Validity.

►Pragmatic CampPragmatic Camp: What are the : What are the practical benefits of using IQ tests? practical benefits of using IQ tests? Focus on concurrent and predictive Focus on concurrent and predictive validity. validity.

Psychometric Models of Psychometric Models of IntelligenceIntelligence

►GoalGoal: identification of the general & : identification of the general & specific abilities underlying performance specific abilities underlying performance on IQ tests. on IQ tests.

►MethodMethod: these models have been : these models have been developed from the results of factor developed from the results of factor analyses & other statistical procedures.analyses & other statistical procedures.

►RationaleRationale: scores on cognitive ability : scores on cognitive ability tests tend to be highly correlated with tests tend to be highly correlated with one another.one another.

Other Popular ModelsOther Popular Models

► Information Processing ModelsInformation Processing Models: focus on the : focus on the cognitive processes used by the brain to cognitive processes used by the brain to represent information and solve problems.represent information and solve problems.

► Developmental TheoriesDevelopmental Theories: emphasize similarities : emphasize similarities in cognitive development rather than individual in cognitive development rather than individual differences.differences.

Ex. Piaget’s Model of Cognitive Development: Ex. Piaget’s Model of Cognitive Development: intelligence develops as children accommodate intelligence develops as children accommodate and assimilate new information into cognitive and assimilate new information into cognitive maps, which help them understanding the world maps, which help them understanding the world & guide their behavior. & guide their behavior.

Spearman’s Two-Factor Model Spearman’s Two-Factor Model (1927)(1927)

►gg = general ability that influences = general ability that influences performance on all intellectual tasks; performance on all intellectual tasks; this represents the general factor of this represents the general factor of what measures of cognitive ability what measures of cognitive ability have in common.have in common.

►ss = specific factors or intellectual = specific factors or intellectual abilities, such as memory or visual-abilities, such as memory or visual-spatial reasoning.spatial reasoning.

““g”: a statistical entity g”: a statistical entity

Example of Psychometric Example of Psychometric Model by VernonModel by Vernon

V e rb a l F lu e n cy N u m e rc ia l A b ility

V e rba l-E du ca tio n a l

S p a tia l R e a son ing M e cha n ica lC o m pre h en s ion

P sych o m o to r S k ills

P ra c tica l-M e ch a n ica l-S p a tia l

"g "G e ne ra l In te llige n ce

Raymond Cattell: Two-Factor Raymond Cattell: Two-Factor TheoryTheory

►Fluid IntelligenceFluid Intelligence: the ability to solve novel : the ability to solve novel problems, usually measured by nonverbal problems, usually measured by nonverbal tasks. Considered to be influenced more tasks. Considered to be influenced more by genetics and brain physiology than by genetics and brain physiology than environment. Example: Block Design environment. Example: Block Design (WISC-III.)(WISC-III.)

►Crystallized IntelligenceCrystallized Intelligence: problem-solving : problem-solving ability using specific knowledge acquired ability using specific knowledge acquired from the environment. Dependent upon from the environment. Dependent upon education and cultural assimilation. education and cultural assimilation. Example: Similarities Subtest (WASI).Example: Similarities Subtest (WASI).

Calculating IQ ScoresCalculating IQ Scores

Old School Approach:Old School Approach:

Ratio IQRatio IQ

IQ = IQ = Mental AgeMental Age (100)(100)

Actual Age Actual Age

Modern Approach:Modern Approach:

Deviation IQDeviation IQ

IQ = z(15) + 100IQ = z(15) + 100

Wechsler IQ TestsWechsler IQ Tests►Verbal, Performance, & Full Scale IQ’s.Verbal, Performance, & Full Scale IQ’s.►Standard Scores: M = 100 & SD = 15. Standard Scores: M = 100 & SD = 15.

Subscale Scores: M = 10 & SD = 3.Subscale Scores: M = 10 & SD = 3.►Verbal: information, digit span, Verbal: information, digit span,

arithmetic, comprehension, similarities, arithmetic, comprehension, similarities, & vocabulary.& vocabulary.

►Performance: picture completion, picture Performance: picture completion, picture arrangement, block design, object arrangement, block design, object assembly, coding, & mazes. assembly, coding, & mazes.

Qualitative Interpretation of IQ Qualitative Interpretation of IQ Scores Scores

130 and above = 130 and above = “Very Superior”“Very Superior”

120-129 120-129 = = “Superior”“Superior”

110-119110-119 = = “High Average”“High Average”

90-10990-109 = = “Average”“Average”

80-8980-89 = = “Low Average”“Low Average”

70-7970-79 == “Borderline”“Borderline”

Below 70Below 70 = = “Extremely Low”“Extremely Low”

Mental RetardationMental Retardation

► Sub-average intellectual functioning (typically Sub-average intellectual functioning (typically IQ scores below 70, which puts one at the 2IQ scores below 70, which puts one at the 2ndnd percentile) and deficits in adaptive behavior percentile) and deficits in adaptive behavior (e.g., language, self-care skills, home living, (e.g., language, self-care skills, home living, social skills, functional academic skills).social skills, functional academic skills).

► Impairment must occur before age 18.Impairment must occur before age 18.► Approximately 2% of US population.Approximately 2% of US population.

► Mild MR: 50-55 to 70.Mild MR: 50-55 to 70.► Moderate MR: 35-40 to 50-55.Moderate MR: 35-40 to 50-55.

► Severe MR: 20-25 to 35-40.Severe MR: 20-25 to 35-40.► Profound MR: < 20-25.Profound MR: < 20-25.

Mental GiftednessMental Giftedness

►Typically, giftedness is defined as IQ Typically, giftedness is defined as IQ scores above 130 or in the top 2% of the scores above 130 or in the top 2% of the population.population.

►Terman’s Giftedness Study: individuals Terman’s Giftedness Study: individuals with high IQ’s were found to be healthier with high IQ’s were found to be healthier and more successful in school, careers, & and more successful in school, careers, & personal relationships than those with personal relationships than those with lower IQ’s. lower IQ’s.

►However, those with extremely high IQ’s However, those with extremely high IQ’s (>150) may be more likely to experience (>150) may be more likely to experience personal and intrapersonal problems personal and intrapersonal problems

Group Intelligence TestsGroup Intelligence Tests

► Paper-and-Pencil examinations frequently used Paper-and-Pencil examinations frequently used to screen applicants & identify those in need of to screen applicants & identify those in need of more thorough evaluations.more thorough evaluations.

1.1. WWI: Army Alpha & Beta Tests.WWI: Army Alpha & Beta Tests.

2.2. Wonderlic Personnel Test: 50-item instrument Wonderlic Personnel Test: 50-item instrument that provides a quick estimate of cognitive that provides a quick estimate of cognitive ability. Popular in organizational settings to ability. Popular in organizational settings to screen job applicants or make placement screen job applicants or make placement decisions.decisions.

Examples of items: analogies, definitions, Examples of items: analogies, definitions, logical reasoning, math, spatial reasoning, logical reasoning, math, spatial reasoning,

Remember: Errors of PredictionRemember: Errors of Prediction

ED

2018161412108

IQ140

130

120

110

100

90

80

70

60

Bell Curve by Herrnstein and Bell Curve by Herrnstein and Murray (1994)Murray (1994)

► IQ is a legitimate construct, it can be reliably IQ is a legitimate construct, it can be reliably measured, and it has important implications for measured, and it has important implications for individuals and society.individuals and society.

► In our advanced technological society, IQ has In our advanced technological society, IQ has become increasingly more valued and become increasingly more valued and economically rewarded.economically rewarded.

► IQ has become the new means for segregating IQ has become the new means for segregating individuals into different social classes. individuals into different social classes. Recently, there has been the creation of a new Recently, there has been the creation of a new social class: the “cognitive elite.”social class: the “cognitive elite.”

► Americans with lower ability will be increasingly Americans with lower ability will be increasingly cared for by a custodial welfare system. cared for by a custodial welfare system.

Bell Curve . . . . Bell Curve . . . .

► IQ is substantially heritable (40-80%). IQ is substantially heritable (40-80%). ► IQ is positively correlated with success IQ is positively correlated with success

in life as measured by education, in life as measured by education, social status, income, & job social status, income, & job performance.performance.

► IQ is negatively correlated with several IQ is negatively correlated with several social problems, such as poverty, social problems, such as poverty, unemployment, welfare dependency, unemployment, welfare dependency, & crime.& crime.

Overlapping Distributions Overlapping Distributions from “The Bell Curve” from “The Bell Curve”

ResearchResearch

Bell Curve . . . .Bell Curve . . . .► The The averageaverage IQ scores of various racial/ethnic IQ scores of various racial/ethnic

groups differ from one another.groups differ from one another.► White supremacists will be disappointed to learn White supremacists will be disappointed to learn

that Jews score the highest, followed by Eastern that Jews score the highest, followed by Eastern Asians, with whites coming in third.Asians, with whites coming in third.

► The differences among individuals are greater The differences among individuals are greater than the differences between racial/ethnic than the differences between racial/ethnic groups.groups.

► To some extent, the etiology of the racial/ethnic To some extent, the etiology of the racial/ethnic differences is not important. (1) We do not know differences is not important. (1) We do not know how to improve IQ scores and (2) it should make how to improve IQ scores and (2) it should make no difference in how we treat other people. no difference in how we treat other people.

Intelligence: Knowns & Intelligence: Knowns & Unknowns Unknowns

(APA Task Force, 1996).(APA Task Force, 1996).► As a As a groupgroup, IQ scores are relatively stable , IQ scores are relatively stable

after early childhood, but individuals’ after early childhood, but individuals’ scores may change over time. scores may change over time.

► Predictor of school achievement (r Predictor of school achievement (r .50). .50).► Predictor of educational attainment (r Predictor of educational attainment (r

.55). .55).► Predictor of social status & income, but Predictor of social status & income, but

these correlations tend to be much lower.these correlations tend to be much lower.► Predictor of general job performance (rPredictor of general job performance (r

.30 to .50), what Hunter & Schmidt call .30 to .50), what Hunter & Schmidt call validity generalizationvalidity generalization..

Continued. . . . Continued. . . . ► Much of the population variation in IQ Much of the population variation in IQ

scores is related to genetic differences (hscores is related to genetic differences (h2 2 .50), but it is difficult to pinpoint exact .50), but it is difficult to pinpoint exact strength of the relationship.strength of the relationship.

► In general, the major intelligence tests are In general, the major intelligence tests are notnot biased against racial/ethnic minorities biased against racial/ethnic minorities (i.e., equal predictive validity). However, (i.e., equal predictive validity). However, these tests may under-predict the these tests may under-predict the performance of Asian-Americans.performance of Asian-Americans.

► Some evidence indicates that the group Some evidence indicates that the group differences between whites and minority differences between whites and minority groups have been shrinking in recent years. groups have been shrinking in recent years.

Continued . . . Continued . . .

► Males score better on visual-spatial tasks and Males score better on visual-spatial tasks and quantitative reasoning; females score better on quantitative reasoning; females score better on verbal tasks. verbal tasks.

► Schools do affect IQ scores by transmitting Schools do affect IQ scores by transmitting information and cultivating intellectual skills.information and cultivating intellectual skills.

► Intervention programs have been found to Intervention programs have been found to influence IQ scores in short-run, but long-term influence IQ scores in short-run, but long-term changes are not very stable.changes are not very stable.

► IQ scores may be decreased by prenatal IQ scores may be decreased by prenatal exposure to alcohol, malnutrition, & exposure to exposure to alcohol, malnutrition, & exposure to lead. lead.

Intelligence & HeredityIntelligence & Heredity

►Cognitive ability is likely a polygenetic Cognitive ability is likely a polygenetic characteristic. characteristic.

►Heritability Index (hHeritability Index (h22) = proportion of test ) = proportion of test score variance associated with genetic score variance associated with genetic differences among individuals.differences among individuals.

► hh22 typically ranges from .45 to .75; the typically ranges from .45 to .75; the magnitude of the coefficient increases with magnitude of the coefficient increases with age. age.

►Caveat : hCaveat : h2 2 applies to populations, not applies to populations, not individuals.individuals.

Intelligence over the LifespanIntelligence over the Lifespan

► Rankings (deviation IQ’s) tend to stable Rankings (deviation IQ’s) tend to stable throughout life; raw scores typically increase throughout life; raw scores typically increase from childhood to adulthood and then decline from childhood to adulthood and then decline in later adulthood.in later adulthood.

► Those with lower IQ’s or those who are not Those with lower IQ’s or those who are not intellectually engaged are more likely to intellectually engaged are more likely to experience a decline in IQ during middle and experience a decline in IQ during middle and late adulthood.late adulthood.

► Performance on visual-spatial tasks (fluid Performance on visual-spatial tasks (fluid abilities) are more likely to decline with age abilities) are more likely to decline with age than performance on verbal tasks (crystallized than performance on verbal tasks (crystallized abilities).abilities).

►Flynn Effect: average IQ scores increase Flynn Effect: average IQ scores increase about 3 points per decade; this is one about 3 points per decade; this is one reason why tests are re-standardized. reason why tests are re-standardized.

Potential Explanations: greater Potential Explanations: greater complexity & improved nutrition.complexity & improved nutrition.

►Terminal DropTerminal Drop: deterioration in cognitive : deterioration in cognitive and sensory-motor functioning during and sensory-motor functioning during the last few months or years of a the last few months or years of a person’s life.person’s life.