What is an IQ test?What do you think it is measuring?

1.18.2011 DO NOW

Unit 6: Testing & Individual Differences

Standardization and normsReliability and ValidityTypes of testsEthics and standards in testingIntelligenceIntelligence testingKinds of intelligenceHeredity/environment and intelligenceHuman diversity

Key Ideas:

Psychometricians (measurement psychologists): focus on methods for acquiring and analyzing psychological data.

They measure mental traits, abilities, and processes.

Standardization & Norms

Constructs: hypothetical abstractions related to behavior and defined by groups of objects or events.

A good test is standardized, reliable, and valid.

Standardization & Norms

Standardization: two-part test development procedure

first establishes test norms from the test results of the large representative sample

second assures that the test is both administered and scored uniformly for all test takers.

Standardization & Norms

Norms: standards used to compare scores of test takers.

e.g. the mean score of the SAT is 500 and the standard deviation is 100.

the mean score for an IQ test is 100 and the standard deviation is 15.

Standardization & Norms

Reliability: consistency of results over time (repeatability).

Methods of measurement include test-retest, split-half, alternate form.

Reliability & Validity

Test-retest: the same exam is administered to the same group on two different occasions and the scores are compared.

The closer the correlation coefficient is to 1.0, the more reliable the test.

The second test may be better than the first because the test-takers are already familiar with the questions.

Reliability & Validity

Split-half: the score on one half of the test questions is correlated with the score on the other half of the questions to see if they are consistent.

Reliability & Validity

Alternate form/Equivalent form: two different versions of a test on the same material are given to the same test takers, and the scores are correlated.

e.g. If a SAT given on Saturday is different from a SAT given on Sunday, and someone took both and they have high reliability, they should get the same scores on both tests.

Reliability & Validity

Interrater reliability: the extent to which two or more scorers evaluate the responses in the same way.

Reliability & Validity

Validity: test measures what it is supposed to measure.

Methods of measurement include face, content, predictive, and construct.

face validity: does it seem to measure what it’s supposed to be measuring.e.g. giving math problems to test

math ability.

Reliability & Validity

Content validity: the content of the test measures all of the knowledge or skills that are supposed to be included within the domain being tested, according to expert judges.

Criterion related validity: a measure of the extent to which a test’s results correlate with other accepted measures of what is being tested.

Reliability & Validity

Predictive validity: a measure of the extent to which the test accurately forecasts a specific future result.

e.g. the ACT is designed to predict college preparedness.

High scores on the ACT should predict high grades in one’s first year of college.

Reliability & Validity

Construct validity: the extent to which the test actually measures the hypothetical construct or behavior it is designed to assess.

Does a clinical test for schizophrenia successfully discriminates people with schizophrenia from other subjects taking the same test.

Reliability & Validity

Briefly describe one type of reliability and one type of validity.

Reading notes (p. 430 – 467, Mod. 31-33 DUE Friday, Jan. 21st).

1.19.2011 DO NOW

Performance tests: test taker knows how to respond to questions and tries to succeed.e.g. ACT, AP exams

Speed tests: large number of relatively easy items in limited test periods.

Power tests: items of varying difficulty with adequate test period.

Types of Tests

Aptitude tests: assess person’s capacity to learn, predict future performance (e.g. ACT).

Achievement tests: assess what a person has already learned (e.g. AP exam).

Types of Tests

Group tests: test many people at one time.Test taker works aloneCheaperMore objective

Individualized tests: interaction of one examiner with one test taker.ExpensiveSubjective grading

Types of Tests

APA and other guidelines create standards to:promote best interests of client

guard against misuserespect client’s right to know results

Ethics and Standards in Testing

APA and other guidelines create standards to:safeguard dignity. Informed consent is needed.Confidentiality is guaranteed.

Ethics and Standards in Testing

Reification: construct treated as a concrete, tangible object.

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

Intelligence & Intelligence Testing

Stanford-Binet intelligence test: an individual intelligence quotient (IQ) test with IQ calculated using the ratio formula: mental age/chronological age x 100.

Now, IQ is based on deviation from the mean for children and for adults.

Five ability areas are assessed both verbally and nonverbally.

Intelligence & Intelligence Testing

So, if someone’s mental age is 8, and their chronological age is 8, what is their IQ?

Mental age of 15, chronological age of 30.

Mental age of 20, chronological age of 10.

Intelligence & Intelligence Testing

Intelligence & Intelligence Testing

Wechsler intelligence tests: three age-based individual IQ tests: WPPSI (Wechsler Preschool and Primary Scale of Intelligence), WISC (Wechsler Intelligence Scale for Children), WAIS (Wechsler Adult Intelligence Scale).

Intelligence & Intelligence Testing

Two scores: verbal and performanceDifference between the two is helpful for identifying learning disabilities

Deviation IQ score – mean/median/mode = 100; 15 point standard deviation

Good for extremes of gifted and mentally retarded or cognitively disabled.

Intelligence & Intelligence Testing

Degrees of cognitive disability (mental retardation):

Mild – IQ 50-70: can self-care, hold job, may live independently, form social relationships.

Moderate – IQ 35-49: may self-care, hold menial job, function in group home.

Intelligence & Intelligence Testing

Degrees of cognitive disability (mental retardation):

Severe – IQ 20-34: limited language and limited self-care, lack social skills, require care.

Profound – IQ under 20: require complete custodial care.

Intelligence & Intelligence Testing

Factor analysis: a statistical procedure that identifies common factors among groups of items by determining which variables have a high degree of correlation.

Charles Spearman used factor analysis to identify g: general factor underlying all intelligence.

s: less important specialized abilities

Intelligence & Intelligence Testing

Briefly describe one of the types of tests discussed yesterday AND GIVE AN EXAMPLE.

Reading notes (p. 430 – 467, Mod. 31-33 DUE Friday, Jan. 21st).

Online IQ test: www.intelligencetest.com/

1.20.2011 DO NOW

Thurstone’s primary mental abilities – seven distinct intelligence factors.

Intelligence & Intelligence Testing

John Horn and Raymond Cattell identified two intelligence factors:

Fluid intelligence: those cognitive abilities requiring speed or rapid learning that tend to diminish with adult aging.

e.g. math and science skills

Intelligence & Intelligence Testing

Crystallized intelligence: learned knowledge and skills, such as vocabulary, which tend to increase with age.

e.g. language and writing skills

Intelligence & Intelligence Testing

Multiple intelligences: Howard Gardner’s theory that people process information differently and intelligence is composed of many different factors, including at least eight intelligences: logical-mathematical, verbal-linguistic, spatial, bodily-kinesthetic, musical, interpersonal, intrapersonal, and naturalistic.

Intelligence & Intelligence Testing

Emotional intelligence: Peter Salovey and John Mayer’s construct defined as the ability to perceive, express, understand, and regulate emotions.

Similar to Gardner’s interpersonal and intrapersonal intelligences.

Intelligence & Intelligence Testing

Triarchic theory of intelligence: Robert Sternberg’s idea of three separate and testable intelligences: analytical (facts), practical (“street smarts”), and creative (seeing multiple solutions).

Intelligence & Intelligence Testing

Creativity: the ability to generate ideas and solutions that are original, novel, and useful is not usually measured by intelligence tests.

Threshold theory: a certain level of intelligence is necessary, but not sufficient for creative work.

Intelligence & Intelligence Testing

Both nature and nurture contribute to intelligence.

Down syndrome is primarily hereditary.

fetal alcohol syndrome (FAS) is primarily environmental.

Phenylketonuria (PKU) results form both nature and nurture.

Heredity/Environment & Intelligence

Cultural-familial retardation: retardation attributed to sociocultural deprivation.

In twin studies, correlation of IQs of identical twins was much higher than fraternal twins or siblings (favoring nature).

Heredity/Environment & Intelligence

Flynn effect: steady increase in performance on IQ tests over the last 80 years, possibly resulting from better nutrition, educational opportunities, and health care (favoring nurture).

Heritability: the proportion of variation among individuals in a population that results from genetic causes.Heritability for intelligence is 50 to

75%.

Heredity/Environment & Intelligence

Within-group differences: range of scores for variables being measured for a group of individuals.

Between-group differences: usually the difference between means of two groups of individuals for a common variable.

Human Diversity

Stereotype threat: Claude Steele’s concept that anxiety influences achievement of members of a group concerned that their performance on a test will confirm a negative stereotype.

This may account for lower scores of blacks on intelligence tests or girls on math tests.

Human Diversity