Chapter 6: Wechsler Scales PDF

Definitions of Intelligence 1. Operational Definition: FSIQ FSIQ stands for "Full-Scale Intelligence Quotient." It is a standardized score used to measure a person’s intelligence, typically through IQ tests like the Wechsler Intelligence Scale or Stanford-Binet tests. Thi...

Definitions of Intelligence 1. Operational Definition: FSIQ FSIQ stands for "Full-Scale Intelligence Quotient." It is a standardized score used to measure a person’s intelligence, typically through IQ tests like the Wechsler Intelligence Scale or Stanford-Binet tests. This score provides a practical, measurable way to assess intelligence for research or clinical purposes. 2. Real (Expert) Definitions These definitions reflect what intelligence truly means according to experts in the field. Spearman (1904): o Proposed the concept of a "general intelligence" factor (g-factor). o Suggested intelligence is the ability to identify patterns and relationships among different things. o Believed that general intelligence underlies performance in all intellectual tasks. Binet (1905): o Focused on intelligence as the ability to judge, reason, and understand well. o Developed the first intelligence test to help identify children who needed special educational assistance. Terman (1916): o Defined intelligence as the ability to form and understand concepts. o Adapted Binet’s test into the Stanford-Binet Intelligence Scale, which became widely used in the United States. Pintner (1921): o Emphasized the importance of adaptability in new and changing situations as a key part of intelligence. o Highlighted that intelligence is not just about knowledge but about applying it effectively in real-world challenges. Wechsler (1939): o Broadened the definition to include acting purposefully, thinking rationally, and dealing effectively with one’s environment. o Believed intelligence is a global capacity, meaning it encompasses a wide range of abilities, not just a single skill.  o Created the Wechsler Adult Intelligence Scale (WAIS), which is still used today. Piaget (1972): o Defined intelligence as the ability to optimize adaptation to one’s physical and social environment. o Believed intelligence develops through interaction with the environment and is tied to stages of cognitive development. 3. Layperson and Expert Conceptions of Intelligence There is often a gap between how the general public (laypeople) and psychologists (experts) view intelligence. o Layperson view: Intelligence may be seen in terms of practical skills, common sense, creativity, or academic success. o Expert view: Experts focus on theoretical and measurable aspects of intelligence, such as cognitive processes, problem-solving, and adaptability. This distinction helps highlight the diverse ways intelligence can be understood and applied in everyday life versus academic settings. Galton and Sensory Keenness 1. Theory: Intelligence and Sensory Abilities Sir Francis Galton proposed that intelligence is linked to sensory keenness, such as the ability to see, hear, or perceive stimuli with great accuracy. He believed that sharper sensory abilities reflected higher intelligence since they provided the foundation for acquiring and processing knowledge. 2. Psychometric Dead End The approach of linking intelligence to sensory perception ultimately failed to provide a useful or reliable measure of intelligence. This theory did not hold up under further scientific scrutiny and lacked predictive power for understanding complex intellectual abilities. 3. Vestiges in Modern Chronometric Analysis While Galton's sensory keenness theory is no longer valid, some ideas from his approach influenced modern methods of studying intelligence. Modern chronometric approaches analyze reaction times and cognitive processing speeds, concepts that echo Galton’s focus on basic mental functions. 4. Problems with Early Chronometric Approaches Early methods for measuring intelligence using reaction times or sensory tasks were inconsistent and poorly standardized. This lack of standardization made it difficult to compare results or draw meaningful conclusions about intelligence. Spearman and the g Factor 1. General Factor (g Factor) Charles Spearman proposed the g factor, which stands for "general intelligence." It represents a single underlying ability that influences performance across a wide range of cognitive tasks. The g factor explains why people who perform well in one type of intellectual task (e.g., math) often do well in others (e.g., problem-solving). This idea suggests intelligence is a broad, overall capacity rather than a collection of unrelated skills. 2. Specific Factors Spearman also acknowledged specific factors, which are abilities unique to particular tasks (e.g., artistic talent or physical coordination). These factors operate alongside the g factor, influencing performance in specialized areas. 3. Relation to Gardner’s Theory of Multiple Intelligences Howard Gardner later challenged Spearman's single general intelligence model by proposing Multiple Intelligences. Gardner’s theory identifies several distinct types of intelligence: o Linguistic: Ability to use language effectively (writers, poets). o Logical-Mathematical: Skill in math, reasoning, and problem-solving. o Spatial: Capacity to visualize and manipulate objects in space (architects, designers). o Musical: Sensitivity to sound patterns and rhythms (musicians, composers). o Bodily-Kinesthetic: Control of body movements and physical tasks (athletes, dancers). o Interpersonal: Understanding and interacting effectively with others. o Intrapersonal: Self-awareness and understanding one's emotions and motivations. The Wechsler Intelligence Scales 1. First Published in 1939 The Wechsler-Bellevue Intelligence Scale (W-B) was introduced in 1939. This was two years after the revision of the Binet Scale, a previous intelligence test developed by Alfred Binet. It marked a significant development in intelligence testing by focusing on broader aspects of intellectual abilities. 2. Wechsler-Bellevue Intelligence Scale (W-B) Created by David Wechsler, a psychologist aiming to improve upon existing intelligence tests. Named the test after himself and Bellevue Hospital, where he worked at the time. Focused on making the test more applicable to everyday adult functioning. 3. Moved Away from a Single-Number Summary Unlike earlier IQ tests (e.g., the Binet Scale), the Wechsler Scale did not just provide a single IQ score. It divided intelligence into different areas, measuring multiple abilities separately. o Examples include verbal comprehension, working memory, and processing speed. This allowed for a more detailed understanding of an individual’s strengths and weaknesses. 4. Adapted the Binet Scale for Adults The Wechsler Intelligence Scales were designed to assess adults, addressing a gap in earlier intelligence testing, which was mainly focused on children. Tasks were created to be more relevant to adult experiences and challenges. The Performance Scale Concept 1. Nonverbal Intelligence The Wechsler-Bellevue (W-B) Intelligence Scale introduced ways to assess nonverbal intelligence, which early Binet scales largely ignored. Nonverbal intelligence includes abilities like problem-solving, spatial reasoning, and visual- motor skills.  This was particularly valuable because it provided a better assessment for individuals beyond just children, as early tests were more child-focused. 2. Original W-B: Two Scales The original Wechsler-Bellevue test consisted of two main scales: o Verbal Scale: Assessed abilities requiring language, such as vocabulary and comprehension. o Performance Scale: Measured abilities that did not rely on language, such as puzzles, pattern recognition, or object assembly. 3. Modern Versions: Expanded Scales More recent versions of the Wechsler Intelligence Scale (e.g., WAIS) have expanded to include five major scales, such as: o Verbal Comprehension o Working Memory o Perceptual Reasoning o Processing Speed o Full-Scale IQ (overall score combining all areas) 4. Reducing Bias from Language and Culture The Performance Scale was designed to reduce cultural and linguistic biases that often affected verbal tests. How it reduced bias: o By using tasks that relied on nonverbal reasoning, visual patterns, or manual dexterity, individuals who spoke different languages or came from different cultural backgrounds could be assessed more fairly. o This made the test more inclusive and applicable across diverse populations. From the WAIS to the WAIS-IV: David Wechsler – Innovator or Borrower? 1. Wechsler-Bellevue Intelligence Scale (1939) This was David Wechsler’s original intelligence test. It set the foundation for modern IQ testing, emphasizing both verbal and performance (nonverbal) abilities. Initially built upon and improved the Binet scale by adapting it for adult use and incorporating nonverbal measures. 2. Wechsler Adult Intelligence Scale (WAIS) (1955) The WAIS replaced the original Wechsler-Bellevue test. It became the standard for assessing adult intelligence. Introduced more modern approaches to testing, including better age-specific norms. 3. Key Updates to the WAIS: WAIS-R (1981): Revised version of the WAIS. o Improved test reliability and validity. o Included updated norms to reflect a more modern population. WAIS-III (1997): o Expanded the number of cognitive areas tested, adding measures for working memory and processing speed. o Provided a more comprehensive assessment of intelligence. WAIS-IV (2008): o Further refined the structure with updated subtests. o Used an even more representative sample for standardization, ensuring better applicability across diverse populations. o Split IQ into four index scores: Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed. 4. WAIS-V – Stay Tuned! The slide hints at an upcoming version of the test (WAIS-V), possibly with further updates to subtests, scoring, and standardization techniques. 5. Later Versions: More Representative Standardization One major improvement in later versions was the use of a more representative standardization sample. o The early Wechsler-Bellevue scale had limitations due to less diverse sampling. o Later versions accounted for differences in age, gender, culture, and socioeconomic background, making the tests more accurate and fair. Age-Related Changes in Intelligence 1. Early Cross-Sectional Research Early studies using cross-sectional methods (comparing different age groups at one time) suggested that intelligence declines slowly with age.  These findings were limited because they didn’t account for differences between generations (cohort effects), such as education or access to resources. 2. More Sophisticated Studies Later studies, particularly longitudinal research (following the same people over time), showed minimal decline in intelligence with age. These findings indicated that cognitive decline may not be as inevitable or severe as earlier studies suggested. 3. Fluid vs. Crystallized Intelligence Fluid Intelligence: o Refers to problem-solving, reasoning, and the ability to adapt to new situations. o Peaks in early adulthood and begins to decline rapidly with age. o This decline is linked to changes in processing speed and memory capacity. Crystallized Intelligence: o Refers to accumulated knowledge, experience, and skills gained over time (e.g., vocabulary or general knowledge). o Gradually increases with age, as people continue to learn and draw on past experiences. 4. Differences Between Adult and Child/Adolescent Intelligence Adult intelligence is fundamentally different from intelligence in children and adolescents. The life experience and knowledge base of adults make direct comparisons between the two groups less meaningful. For example, while children excel in acquiring new information (fluid intelligence), adults may rely more on knowledge they’ve already acquired (crystallized intelligence). Generational Changes in IQ Scores 1. Flynn Effect: IQ Inflation The Flynn Effect describes a phenomenon where IQ scores have steadily increased over generations. Specific Increases: o Between 1965 and 1972, IQ scores increased by about 4 points. o Between 1932 and 1981, scores increased by 14 points.  This suggests that average intelligence (as measured by IQ tests) is rising over time, but it doesn’t necessarily mean people are inherently "smarter." 2. Explanations by Flynn IQ Tests Do Not Measure Intelligence: o Flynn argued that IQ tests primarily assess abstract problem-solving abilities rather than overall intelligence. Shifting Definitions of Intelligence: o Over time, what we consider "intelligence" has changed, and tests have been adjusted accordingly. o IQ tests may now place greater emphasis on skills like reasoning or problem- solving, which align with modern educational and societal demands. 3. Other Explanations for the Flynn Effect Several factors have been proposed to explain why IQ scores are increasing over generations: o Better Nutrition: ▪ Improved diets lead to better brain development and overall cognitive functioning. o Improved Healthcare and Reduced Environmental Risks: ▪ Advances in healthcare, cleaner living conditions, and reduced exposure to harmful substances (like lead) contribute to better mental development. o Greater Educational Access and Requirements: ▪ More people now have access to formal education, and schooling has become more rigorous, emphasizing critical thinking and abstract reasoning. o Increased Environmental Complexity: ▪ Modern environments (e.g., technology, media, problem-solving in everyday life) demand more abstract thinking, which boosts performance on IQ tests. WAIS-IV Subtests The Wechsler Adult Intelligence Scale (WAIS-IV) includes various subtests designed to measure specific cognitive functions. Here’s a breakdown of what each subtest measures: 1. Vocabulary  Major Function Measured: o Assesses word knowledge and verbal reasoning. o Evaluates a person's understanding and use of language. Example Task: o Define words or explain their meaning. 2. Similarities Major Function Measured: o Tests abstract thinking and verbal reasoning. o Measures the ability to identify how two things are alike conceptually. Example Task: o "How are a dog and a cat alike?" 3. Arithmetic Major Function Measured: o Focuses on attention, working memory, and strategy use for solving mental math problems. Example Task: o Solve a math problem without a calculator or paper. 4. Digit Span Major Function Measured: o Evaluates immediate memory, attention, and working memory. Example Task: o Repeat a series of numbers in order or reverse order. 5. Information Major Function Measured: o Tests the individual’s range of knowledge across various subjects. Example Task: o Answer general knowledge questions (e.g., "Who wrote Hamlet?"). 6. Coding Major Function Measured: o Measures visual-motor processing speed (fine motor coordination and speed). Example Task: o Copy symbols paired with numbers as quickly as possible. 7. Block Design Major Function Measured: o Assesses visuomotor construction and spatial reasoning. Example Task: o Recreate geometric patterns using blocks. 8. Matrix Reasoning Major Function Measured: o Tests nonverbal/perceptual reasoning. Example Task: o Choose the piece that completes a visual pattern. 9. Visual Puzzles Major Function Measured: o Another test of nonverbal/perceptual reasoning. Example Task: o Identify which pieces fit together to form a complete puzzle. 10. Symbol Search Major Function Measured: o Assesses visual-motor processing speed with a focus on scanning ability. Example Task: o Search for target symbols in a list as quickly as possible. Scales, Subtests, and Indexes 1. Index Scores on the WAIS  Index scores combine two or more subtests that measure similar skills (e.g., verbal comprehension or working memory). Combining subtests increases the reliability (rₓᵧ) of the score, making it more consistent across related tasks. Scores must be interpreted carefully to distinguish between actual cognitive improvements and statistical artifacts. o Statistical artifacts may occur due to: ▪ Regression Toward the Mean (Galton): Scores naturally move closer to the average over time. ▪ Standard Error of Measurement (SEM): SEM differs across test levels: ▪ FSIQ (Full-Scale IQ) has the lowest measurement error. ▪ Index scores have moderate error. ▪ Individual subtests have the highest error. 2. Not All Subtests Are Created Equal Subtests differ in how much they contribute to the overall intelligence score (FSIQ). Verbal Comprehension (VC) has the strongest correlation (rₓᵧ) with FSIQ compared to other subtests, making it a key component in measuring overall intelligence. 3. Change from the Original Two-Score Model The original Wechsler-Bellevue test divided intelligence into two broad scores: o Verbal Intelligence o Performance (Nonverbal) Intelligence The modern WAIS replaced this model with multiple index scores, providing a more detailed understanding of cognitive abilities and reflecting advances in psychological testing. WAIS-IV Indices 1. Verbal Comprehension Index (VCI) Measures the ability to understand and use language effectively. Subtests: o Vocabulary: Knowledge of word meanings and definitions. o Similarities: Ability to recognize how two things are conceptually alike. o Information: General knowledge about the world. 2. Perceptual Organization Index (POI)  Assesses nonverbal reasoning and spatial problem-solving skills. Subtests: o Picture Completion: Ability to identify missing elements in visual scenes. o Block Design: Using blocks to recreate specific visual patterns. o Matrix Reasoning: Identifying patterns and completing visual sequences. 3. Working Memory Index (WMI) Evaluates short-term memory, attention, and the ability to manipulate information mentally. Subtests: o Arithmetic: Solving math problems in your head. o Digit Span: Repeating number sequences forwards and backward. o Letter-Number Sequencing: Reordering sequences of mixed letters and numbers. 4. Processing Speed Index (PSI) Measures the ability to process simple tasks quickly and accurately. Subtests: o Digit Symbol-Coding: Copying symbols as quickly as possible. o Symbol Search: Identifying specific symbols within a set as quickly as possible. Raw Scores to Scaled Scores 1. Raw Scores Each subtest in the WAIS-IV produces a raw score, which is simply the total number of correct answers given by the test-taker. 2. Conversion to Scaled Scores The raw score is converted into a scaled score for easier comparison and interpretation. Scaled scores for each subtest have: o Mean = 10 (average score is 10 across the population). o Standard Deviation = 3 (most scores fall within 3 points of the mean). 3. Index Scores Scaled scores from multiple subtests are combined to calculate index scores (e.g., Verbal Comprehension Index, Working Memory Index). Index scores represent overall ability in specific cognitive areas and have: o Mean = 100 (average score is 100 across the population). o Standard Deviation = 15 (most scores fall within 15 points of the mean). Index Scores and FSIQ (M = 100, SD = 15) 1. Verbal Comprehension Measures crystallized intelligence, which reflects knowledge acquired through experience and education. Includes abilities like understanding and using language effectively, problem-solving with verbal reasoning, and accessing long-term knowledge. 2. Perceptual Organization Assesses fluid intelligence, which involves reasoning and problem-solving in novel situations. Focuses on spatial reasoning, pattern recognition, and visual-motor integration. 3. Working Memory (Auditory) Evaluates complex attention, multitasking, and the ability to process and manipulate information in real time. Specifically examines auditory processing and short-term memory capacity. 4. Processing Speed Measures psychomotor speed, or how quickly and accurately one can complete simple cognitive tasks. Reflects efficiency in processing and responding to visual and motor tasks. 5. Full-Scale IQ (FSIQ) Calculated by summing the four index scores (Verbal Comprehension, Perceptual Organization, Working Memory, and Processing Speed). Provides a composite measure of overall cognitive ability. 6. General Ability Index (GAI) Estimates pre-morbid ability, which refers to an individual’s cognitive functioning before any illness, injury, or decline. Excludes working memory and processing speed to focus on core reasoning and knowledge abilities. Pattern Analysis 1. What is Pattern Analysis?  Involves evaluating large discrepancies between subtest scaled scores in intelligence testing. These discrepancies can provide potential insights into emotional or psychological problems. 2. Challenges in Validity Research on the effectiveness and reliability of pattern analysis has been inconsistent and inconclusive. Specific issues include: o Lack of Standardized Methodology: No universal approach exists for conducting and interpreting pattern analysis. o Multiple Underlying Causes: A specific pattern in scores may result from different underlying issues, making interpretation difficult. o Statistical Artifacts: Discrepancies in scores may sometimes be random variations or statistical errors rather than meaningful patterns. 3. Current Use of Pattern Analysis Pattern analysis should primarily be used for hypothesis generation rather than definitive conclusions. It can be a tool to explore potential avenues for further assessment but should not be heavily relied upon until more research validates its use. 4. Limitations The inconsistent utility of pattern analysis likely stems from the combination of: o Lack of methodological rigor. o The complexity of interpreting patterns that may not have a single clear cause. o Statistical limitations that can obscure meaningful findings. Psychometric Properties of the Wechsler Adult Scale 1. Standardization The test is standardized using a sample of 2200 adults. These adults were divided into 13 age groups and 13 specialty groups to ensure the test results are representative of the general population and specific subgroups. Standardization helps to establish norms for interpreting scores. 2. Reliability  The Wechsler Adult Scale is known for high reliability, meaning it produces consistent results over time and across different testing situations. This includes: o Internal Reliability: Consistency of results across subtests within the same administration. o Temporal Stability: Consistency of results when the test is taken at different times by the same individual. 3. Validity The Wechsler Adult Scale is considered one of the most valid IQ tests in the world. Validity means the test accurately measures what it is designed to measure (intelligence) and provides meaningful and interpretable results. Downward Extensions of the WAIS Wechsler Intelligence Scale for Children (WISC) Designed as a child-specific adaptation of the WAIS to measure intelligence in younger age groups. Age Range: Suitable for children aged 6 to 16 years. First Developed: Introduced in 1949 by David Wechsler. Revisions: o Revised in 1974, 1991, 2003, and 2014 to improve its accuracy and adapt to evolving research in intelligence testing. Current Version: The test is now in its fifth edition (WISC-V). Downward Extensions of the WAIS Wechsler Preschool and Primary Scale of Intelligence (WPPSI) Designed to assess intelligence in very young children. Age Range: Suitable for children aged 2.5 years to 7 years, 7 months. First Developed: Introduced in 1967 by David Wechsler as a preschool adaptation of the WAIS. Revisions: o Revised in 1989, 2003, and 2012 to improve accuracy, adapt to developmental research, and include modern subtests.  Current Version: The test is in its fourth edition (WPPSI-IV). The WISC-V (Wechsler Intelligence Scale for Children – Fifth Edition) 1. Improvements Over Previous Versions The WISC-V includes enhanced psychometric properties, such as better reliability and validity compared to earlier versions. These improvements make the test more precise and adaptable for modern assessment needs. 2. Follows the Model of WAIS-IV The structure of the WISC-V is based on the framework of the WAIS-IV, focusing on index scores rather than a single IQ score. It provides a more comprehensive assessment of cognitive abilities by evaluating multiple domains. 3. Use of Pattern Analysis The WISC-V still utilizes pattern analysis and comparisons between index scores to identify potential cognitive strengths and weaknesses. However, these practices remain questionable due to inconsistent research findings and the risk of over-interpreting score discrepancies. 4. Validity With Special Groups The validity of the WISC-V has been extensively studied with various special populations, such as children with learning disabilities, ADHD, and other developmental conditions. This research ensures the test is effective and appropriate for diverse groups. The WPPSI-IV (Wechsler Preschool and Primary Scale of Intelligence – Fourth Edition) 1. Extended Age of Testability The WPPSI-IV expanded the range of children it can assess, now including very young children (starting at 2.5 years). Relative Concept: Tasks are designed to be developmentally appropriate, such as interpreting simple language ("I want ice cream") or identifying objects. 2. Flexibility The test is more adaptable to the specific needs and abilities of the child being assessed.  Adjustments can be made based on the child’s developmental level to ensure accurate results. 3. Hierarchical Structure The WPPSI-IV follows the same hierarchical model as the WISC-V, breaking down cognitive abilities into multiple indices for a comprehensive evaluation. 4. Compatibility With Adaptive Functioning The WPPSI-IV is designed to integrate with assessments of adaptive functioning, such as daily living skills, to provide more diagnostic insights. This is particularly useful in identifying developmental delays or other conditions. 5. Strong Psychometric Properties Research shows the WPPSI-IV has high reliability and validity, ensuring consistent and accurate assessments across diverse populations. Individual Tests of Achievement 1. Purpose of Achievement Tests These tests are designed to evaluate what a person has learned in school or through other educational experiences. They measure current knowledge and skills, often focusing on specific academic areas such as reading, math, or writing. 2. Identifying Learning Disabilities A learning disability is identified when there is a significant discrepancy between: o Intelligence (Potential): What the person is capable of achieving based on their intellectual ability. o Achievement (Current Skill Level): What the person has actually learned or can demonstrate in academic tasks. For example, a student with high intelligence but poor reading skills might be diagnosed with a reading disability if this gap is significant. Nature & Assessment of Learning Disabilities 1. Definitions A learning disability (LD) is characterized by:  o Discrepancy between Ability and Achievement: A significant gap between a person’s intellectual potential (ability) and their actual academic performance (achievement). o Significant Difficulties in Knowledge Acquisition: Challenges in learning and mastering new skills or information. o RTI (Response to Intervention): A diagnostic approach where interventions are provided, and the individual’s progress is monitored to determine if the issue stems from a learning disability. 2. Essential Features of Learning Disabilities Intra-Individual Discrepancy in Cognitive Functioning: o Learning disabilities often involve uneven cognitive abilities within an individual. For example, they may excel in some areas (e.g., reasoning) but struggle in others (e.g., reading or writing). Exclusionary Clause (What LD is NOT): o A learning disability is not due to: ▪ Intellectual Disabilities (ID): General intellectual impairments. ▪ Sensory Deficits: Vision or hearing impairments. ▪ Economic Disadvantage: Environmental factors like poverty. Heterogeneity: o Learning disabilities are not uniform; there is significant variation in how they present. o Subtyping efforts (e.g., Nonverbal Learning Disability (NVLD) by Byron Rourke) are ongoing to categorize specific types of LDs and their unique features.