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Weschler Tests
WAIS: Adult Intelligence ScaleWISC: Intelligence Scale for Children
WPPSI: Preschool and Primary Scale of Intelligence
History 1939: Weschler Bellvue 1950: WISC 1955: WAIS 1974: WISC-R 1981: WAIS – R 1997: WAIS-III 2002: WPPSI-III 2003: WISC IV
Rationale for Weschler’s tests
More appropriate content for adults on the WAIS
Broader coverage the Stanford Binet
Separate scores for components of intelligence
Better norms
Stratified Sampling in WAIS
For an test to be used for all adults in the US, what variables should stratified on in the sampling?
Variables used to select a stratified sample in WAIS
Age: 13 age groups, 16 to 89 Sex: M, F Race: White, non-white Geographic region: 4 regions Occupation: 6 occupational groups Education Residence: urban, rural
Example using 1995 Census
Consideration of a combination of region, age, and sex
Structure of WAIS Scores on 19 scales in several
content areas: Information, Block Design, Word Reasoning
Scores on traditional theoretical organization of Verbal IQ, Performance IQ, and Full Scale IQ
Scores on four Indices resulting from factor analysis of the 19 content scales
Profile Analysis: pathologies show more scatter, e.g. schizo
Low Middle High Compre X Arith X Similarities X Vocab X Digit X
Block X Coding X Objec Assem X Digit Symbol X
Profile Analysis: Brain damage
Low Middle High
Compre X Arith X Similarities X Vocab X Digit X
Block X Coding X Objec Assem X Digit Symbol X
Profile Analysis: Psychopathic character disorder
Low Middle High
Compre X Arith X Similarities X Vocab X Digit X
Block X Coding X Objec Assem X Digit Symbol X
Group Tests of Cognitive Abilities
Can be administered to more than one person at a time
Historically called “paper and pencil” tests
Now can be administered electronically On computer On line, web-based systems (ISSUES!!)
Advantages
Standardization Examiner has no/small influence Mass testing Multiple choice format simplifies
scoring Scoring can be objective Adaptive testing Better norms
Disadvantages Examiner cannot make observations
about each individual, e.g. is person ill Restrictions on the response mode: just
make on paper (?) More difficult to have individuals take
different questions Difficult to measure certain attributes,
e.g., sensori-motor functions Not appropriate for certain individuals,
e.g., inexperienced with these formats
Scholastic Aptitude Tests
SAT ACT GRE MCAT LSAT
Some Paper and Pencil Tests of “g”
Hidden Figures Test -Gottschaldt Figures
Matrices Raven Progressive Matrices
Figural Patterns Cattell Culture Fair Intelligence Test
Wonderlic Personnel Test A measure of general mental ability “g” Short, timed, 12 minutes Several forms: 11 languages, Braille, large 50 items
Spiral omnibus format: gets more difficult, changing topics
Word comparisons, disarranged sentences, following directions, number comparisons, number series, story problems, spatial, logic
Primary Mental Abilities
Thurstone, 1938 Weschler 7 to 9 cognitive abilities Resulted from theory and research
finding showing clusters of behaviors
Examples of abilities and test items
Verbal comprehension
Vocabulary, synomyms, antonyms, reading
Verbal fluency
Rapid production of words
Number ability
Arith word problems, arith reasoning, arith computation
Spatial visualization
Mental manipulation of symbols and figures
Memory Recall of words, paired associates, coding tasks
Reasoning Analogies, series
Perceptual speed
Cross out “Ls” ALMJLBEL
Multiple Aptitude Test Batteries A “battery” is a coordinated set of tests
measuring several attributes Several test of related abilities
developed, normed, evaluated, and packaged by one publisher
Examples Differential Aptitude Tests (DAT) General Aptitude Test Battery (GATB) Armed Services Vocational Aptitude Battery
(ASVAB)
Differential Aptitude Test (DAT) Verbal Reasoning Numerical Ability Abstract Reasoning Space Relations Mechanical Reasoning Clerical Speed and Accuracy Language Usage Spelling
Psychometric Information on the DAT Norms: national sampling, ½ male and
female, Grades 8 to 12, workers Reliability
Parallel forms: .68 to .86, percentile bands Validity
Predictive of grades in math, science, social studies, English; Follow up study
Support material: brochures, profile forms, career planning using Career Planning Qst
Seven-Year Follow-up Study with DAT
1430 senior high school students examined with DAT, then followed for 7 years to learn what school level and what occupation
Criterion: Education level attained 7 years later
Educ level Advanced degree College graduate Some college Specialty school No further school
Criterion: Education level attained
Educ level Average Verbal Reasoning
Average Numerical
Advanced degree
86 84
College graduate 79 79
Some college 61 57
Specialty school 40 31
No further school
34 30
Criterion:Occupation entered
Job working in?
What test did they get highest score on? And what was mean
Engineers VR = 84, NA = 89
Drafting,engineer aide
SR = 67
Technicians MR = 53
Office jobs Clerical = 64
Sales AR = 58
Other multiple aptitude batteries
General Aptitude Test Battery (GATB) Used in US employment offices Controversy over race norming; CRA
of 1991 Armed Forces Vocational Test
Battery (ASVAB) Used in military induction centers
Guilford’s Structure of Intellect Model
“Search model” – has heuristic value 120 facets of intelligence 5 Operations: kinds of mental
processes 4 Contents:what you are thinking
about 6 Products: the form in which the
information occurs
Ex: Cognition of semantic…
Units: vocabulary, synonyms Classes: verbal classifications Relations: verbal analogies, order Systems: arithmetic operations Transformations: similarities Implications: “Effects” test
Creativity: Divergent Thinking about ….
Various Content <-->
Various Products
Figures Units
Symbols Classes
Word = semantics Relations
Behaviors Systems
Transformations
Implications
Other Tests of Specific Abilities
Emotional Intelligence Gardner’s Multiple Intelligences
Disabilities and Testing
Diagnosing disabilities Accommodating disabled
individuals in testing
Definitions
Child experiencing delays, or has condition which will result in delay Individuals With Disabilities Act
(1997) Adult with a physical or mental
impairment that limits a major life activity American With Disabilities Act (1990)
Diagnosing disabilities
Must be done by a qualified examiner
Must be documented in some formal, proven way
Poor performance is not necessarily the result of a disability
Assessing various types of disabilities Physical
Vision: optical expert Hearing: audiologist Motor: special ed person, PT, med doc
Mental/cognitive Mental retardation: “IQ” tests: WISC Adaptive behavior: Vineland Emotional: personality tests, behavioral
observations
Accommodations
Access Services Testing
Forms, mode of response, environment, aids, time allowed
Standards for Educ and Psych Tests Ethical Principles of Psychologists
Two Points of View
Tests are biased
Tests are not biased
Psychometric Terms related to test bias Adverse Impact
Mean difference in scores Disproportionate selection rates
Bias in measurement = slope bias Differential validity: difference in r
Bias in prediction = intercept bias Unfair discrimination Systematic under-prediction of success
“Tests are biased”
Arguments that cognitive ability tests are BIASED and should NOT be used to assess minorities
Tests are biased African Americans score 10-15 points
lower than whites; Hispanic/Latinos score 5 – 7 points lower than whites
5 point difference remains after using controls
IQ tests have white, anglo-saxon, middle class content
Ethnic minorities score lower because of differences in motivation and exposure to tests
Tests are biased, continued Tests are differentially valid (slope bias) Tests under-predict success for minorities
(“intercept bias”) Validation research has used poor criteria Test results induce negative expectations IQ is partially environmentally determined Use alternatives
Heritability Heritability is the proportion of total
variance in test scores due to genetic factors: h squared
Total test variance = variance due to genetics + variance due to environment
Estimates of heritability in cognitive ability: Some testing texts: 30- 40% General literature: 50 – 70% Older ages: 80%
Twins’ studies
Correlation of test scores
Identical twins reared together
.91
Identical twins reared apart .75
Fraternal twins reared together
.55
Fraternal twins reared apart .30
Siblings .50
Natural parent and child .44
Adoptive parent and child .02
Tests are not biased
Arguments that cognitive ability tests are NOT biased and should be used to assess minorities
Tests are not biased
African Americans and Hispanis score lower on numerous tests of cognitive ability
Test score differences persist even after controls for SES and even with the use of culture free and culture fair cognitive tests
Culturally different individuals from other groups do as well as whites
White examiners do not treat minority examinees differently
Tests are not biased Differential validity (“slope bias”)
occurs no more frequently than chance. Well developed tests are equally valid
Tests do not under-predict success for minorities; if any thing they over-predict success for minorities
Cognitive ability tests predict success in school, occupations, military, life
Tests are not biased Tests provide diagnosis and help
identify special educ and enrichment
Tests serve to evaluate outcomes of program; part of solution
IQ is partially (largely) genetically determined
Alternative are more biased; tests are “color blind”