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Wechsler Intelligence and Memory Scales

Brief outline of Wechsler's Memory and Intelligence Scales

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Wechsler Intelligence and Memory Scales

  1. 1. Wechsler Intelligence and Memory Scales
  2. 2. Wechsler Intelligence Scales
  3. 3. Introduction • Developed by Dr. David Wechsler, a clinical psychologist • These are individually administered, composite intelligence tests in a battery format. • Assessment is done in different areas of intellectual ability – Observation of personality in different situations • Three versions of the test provide 3 different IQ scores – performance IQ – verbal IQ – full scale IQ • Considered one of the best psychological tests and are frequently used in clinical practice.
  4. 4. History and Development • In the 1930’s Wechsler studied various standardized tests and initially selected 11 subtests. • “Premise-intelligence” global in nature and represents some part of personality. • 1939: development of the Wechsler Bellevue • 1955: development of the Wechsler Adult Intelligence Scale (WAIS) • 1981: development of WAIS-R
  5. 5. History and Development • 1997 development of (WAIS) – The Wechsler Bellevue originally intended for adults • 1949 Wechsler Intelligence Scale for Children (WISC) developed. • WISC revised in 1974 to WISC-R and in 1991 to WISC-IV • 1967 the development of Wechsler Preschool and Primary School of Intelligence (WPPSI). • Later revised to WPPSI-R in 1989 then to WPPI-IV in 2002
  6. 6. Forms of the Test • Wechsler –Bellevue – Has been revised several times leading to various Editions = WAIS; WAIS R, WAIS III, WAIS IV – Initially developed in 1939, and revised in 1946 • Wechsler Adult Intelligence Scale (WAIS ) - Developed in 1955 due to deficiencies primarily linked to both reliability of the subsets and size of Wechsler –Bellevue • WAIS - R = Developed in 1981 and was based on 1,880 individuals, considered generally more representative. – Wechsler Adult Intelligence Scale - III (WAIS -III ) = Developed in 1997 as a revision to WAIS-R. – Reason = to update norms, extend age range, modify items, develop higher IQ “ceiling” and “Floor”, decrease reliance on timed performance, develop/index factor scores etc. • WAIS - IV = released in 2008, composed of 10 core subtests and five supplemental subtests, with the 10 core subtests comprising the Full Scale IQ
  7. 7. Forms of the Test Wechsler Intelligence Scale for Children (WISC) - Four Editions: – WISC – 1949, WISC-R 1974, WISC III 1991, WISC IV 2003 & WISC V 2014, – 6-16 yrs – Wechsler Intelligence Scale for Children (WISC)- developed for assessing children between 0 and 6 years. Was revised in 1974 – WISC-R. – WISC-R = was standardized on a new sample that was more accurately representative. • (WISC- III)- Developed 1991, revision of WISC. – Major Change = inclusion of four factor/index scores = Verbal Compensation, Perpetual organization, Freedom from Distractibility, and Processing speed. – More reliability and standardization on 2,200 children between 6 and 16 years. • (WISC-IV) – General cognitive abilities: general problem-solving/reasoning skills (verbal, nonverbal, and visual domains) – Working memory and processing speed
  8. 8. Forms of the Test Wechsler Preschool and Primary Scale of Intelligence (4-6yrs) • Wechsler Preschool and Primary Scale of Intelligence (WPPSI) – A downward extension of WISC, Developed in 1967. – In response to an increasing need for the assessment of preschoolers. – Wechsler Preschool and Primary Scale of Intelligence- Revised (WPPSI - R) = A revision of WPPSI in 1989. – expanded the age range to 3–7 years 3 months and introduced a new subtest, Object Assembly. • (WPPSI - III) – Additional subtests to enhance the measurement of Fluid Reasoning. (Matrix Reasoning, Picture Concepts, Word Reasoning and Measures of Processing Speed) • (WPPSI - IV) – Working Memory subtests added (Picture Memory and Bug Search) – Processing Speed subtests added ( Bug Search, Animal Coding, and Cancellation) • provides Verbal and Performance IQ scores as well as a Full Scale IQ score
  9. 9. Test Description (WAIS) • The WAIS-III is composed of 14 subtests. • Eleven of the subtests produce the three summary scores of Verbal IQ, Performance IQ, and Full Scale IQ. • The verbal subtests include: – Vocabulary, Similarities, Arithmetic, Digit Span, Information, and Comprehension. The performance subtests include Picture Completion, Digit Symbol (Coding), Block Design, Matrix Reasoning, and Picture Arrangement. • Two additional subtests: Letter–Number Sequencing and Symbol Search, are supplemental and included in index scores. • The index scores : – Verbal Comprehension (Vocabulary, Similarities, and Information), – Perceptual Organization (Picture Completion, Block Design, and Matrix Reasoning), – Working Memory (Arithmetic, Digit Span, and Letter–Number Sequencing), – Processing Speed (Digit Symbol and Symbol Search)
  10. 10. Test Description (WISC) • Generates a Full Scale IQ which represents a child's general intellectual ability. • Provides five primary index scores – Verbal Comprehension Index – Visual Spatial Index – Fluid Reasoning Index – Working Memory Index – Processing Speed Index
  11. 11. Test Duration • Administration of the 11 subtests approx. 75 mins – range of 60 to 90 min. • The time needed to administer the 13 subtests required to generate all of the summary and index scores is 80 min – range of 65 to 95 min
  12. 12. What it measures/ How it’s used • Three tests were developed: – The Wechsler Adult Intelligence Scale (WAIS) – Wechsler Intelligence Scale for Children (WISC) – Wechsler Preschool and Primary Scale of intelligence (WPPSI) • Measures intellectual performance through observation of personality in various settings • Measures a full scale IQ (an individual's complete cognitive capacity – verbal and performance) • Measures several variables • academic achievement, • occupational performance etc.
  13. 13. What it measures/ How it’s used • WAIS and WISC provide information on an individual’s cognitive strengths and weaknesses. • Helps also check for cognitive changes – Recovery following after surgery • Provides clinicians, researchers and educators with baseline measures on determining the degree of change in them over time. – evaluate the effectiveness of an educational programme – evaluate changing abilities of a person.
  14. 14. What it measures/ How it’s used • Wechsler scales are scored administered and scored in a similar way • Each test has two batteries of subtests grouped into two general areas: – Verbal scales – measure general knowledge, language, reasoning and memory – Performance scales - measure spatial, sequencing and problem-solving skills. • Trained examiners use a set of complex test materials, test takes approx. 90mins. Raw scores are converted into standard scores.
  15. 15. Intelligence Quotient (IQ) • “Intelligence” Is an individual's ability to adapt and constructively solve problems in the environment. • IQ originally developed by Lewis Terman (1916), proposed this scale for classifying IQ scores: – Over 140 :Genius or near genius – 120-140 : Very superior intelligence – 110-119:Superior intelligence – 90-109: Normal or average intelligence *MA is the mental age *CA is the chronological
  16. 16. IQ Classifications. WAIS: • 130+ Very Superior • 120–129 Superior • 110–119 High Average • 90–109 Average • 80–89 Low Average • 70–79 Borderline • 69- Extremely Low WISC: • 130 + Extremely High • 120–129 Very High • 110–119 High Average • 90–109 Average • 80–89 Low Average • 70–79 Very Low • 69- Extremely Low
  17. 17. Average adult IQ vs. real-life accomplishments Accomplishment IQ • MDs, JDs, and PhDs 125 • College graduates 112 • 1–3 years of college 104 - 110 • Clerical and sales workers 100–105 • High school graduates, skilled 97-100 • 1–3 years of high school 90-95 • Semi-skilled workers 90–95 • Elementary school graduates 90 • Elementary school dropouts 80–85 • Have 50/50 chance of reaching high school 75
  18. 18. Assets • Extensive history of continuous evaluation. • Easy to administer with clear guidelines that limit the possibility of error. • WAIS-III and WISC-III both normed and WAIS-III is co- normed with the WMS-III • Has a very extensive population range. • Great accuracy in predicting academic and occupational performance. • It is possible to gain considerable information on cognitive strengths and weaknesses. • Very useful in tracking cognitive changes over time or after injury/ illness. In individuals and various populations. • Reveals important personality and clinical variables.
  19. 19. Limitations • Reductionist interpretations of test scores label and stereotype. • Very limited capacity in predicting non-academic activity. • They measure present level functioning so can only be used to make short term predictions. • Emphasizing convergent, analytical and scientific modes of thought. • Focus on the outcome of cognition rather than the process • Limited ability in assessing minority groups. • The meaning of some of the subset scores is still not well understood • A degree of subjectivity when scoring • Complexities in calculating scores creates potential for errors • Not much change has been made to the tests despite advancements in theories of intelligence
  20. 20. General Uses • These tests are used not only as intelligence tests, but as a clinical tools • Used as part of an assessment to diagnose ADHD/ADD and learning disabilities • Can be used to show discrepancies between a child's intelligence and his/her performance at school • Can be used as part of an assessment battery to identify intellectual giftedness/ cognitive strengths and weaknesses • To predict future academic achievement • Contribute information concerning a child's developmental and psychological well-being – Very high/ low scores may suggest contributing factors for adjustment difficulties in social contexts
  21. 21. Wechsler Memory Scale
  22. 22. Introduction • Individually administered, composite batteries designed to understand the various components of a person’s memory better. • Currently in the third edition WMS-III and provides full range memory functioning. • Based on current theories of memory and plays a pivotal role in cognitive assessment.
  23. 23. History and Development • There are three editions of the WMS, each has incorporated advances in theoretical understanding of memory. • WMS composed of brief procedures on memory for paired words, simple visual designs, texts and sequences. • The WMS-R had significant improvements such as including age-related norms. • The WMS-IV effectively addresses issues of behaviour and brain relationships involved in memory and learning.
  24. 24. Test Description • The WMS has three primary indexes: – Immediate Memory (immediate recall scores from Logical Memory, Faces, Verbal Paired Associates, and Family Pictures) – General (i.e., delayed) Memory (Auditory Recognition Delay) – Working Memory (Letter/Number Sequencing and Spatial Span) • Additional subtests include Orientation, Word List learning, and Visual Reproduction
  25. 25. Test Duration • Administration time for primary subtests is 30 to 35 min, • Administration of all of the supplemental subtests was estimated to take 15 to 20 min of actual testing time. • Together, administration of the complete WMS should take 45 to 55 min
  26. 26. What it measures/ How it’s used • Used for age group 16-90years. The WMS-IV is designed to measure different memory functions in a person. Checks: – logical memory, – verbal paired associates, – visual reproduction, – spatial addition, – symbol span, – design memory – cognitive screener. • Tests for conditions such as dementia or mild learning difficulties.
  27. 27. What it measures/ How it’s used • The index scores focus on – auditory memory – visual memory – visual working memory – immediate memory – delayed memory
  28. 28. What it measures/ How it’s used • Gives a Brief Cognitive Status Exam – helps to assess global cognitive functioning (memory deficits/ neural, psychiatric, developmental disorders) • Differentiates clinical groups i.e. dementia vs. normal memory functioning. • Can be self administered or by a clinician. – Brief cognitive assessment test (21-point BCAT-SF) six item test/ administered in <5mins , – client is asked to perform simple tasks e.g. show orientation to time, incidental recall, mental control etc. – The test information is presented both verbally and visually.
  29. 29. Assets • Working visual and auditory memory indices are distinct and measurable. • The original WMs was quite short (15 mins) • The complexity of the WMS-III allows it to measure a wide range of memory functions. • Norming of WMS-III with WAIS- III and it’s superior standardization • Mostly has clear guidelines on scoring and administration.
  30. 30. Limitations • Some of the indices are redundant (general and immediate memory indices) • WMS-R and WMS-III take very long to administer (45- 100 minutes). Sometimes practitioners use only subsets introducing a probability of error. • High degree of cultural loading in Logical memory subset I and II. • Lack of guidelines on how to administer Logical memory subsets may lead to variations that affect scores.