76 terms


1 Weschler's View of Intelligence
The capacity of a person to act purposefuly, to think rationally, and to deal effectively with his or her environment.
2 Crystallized Intelligence
Acquired intelligence (Acquired after birth)
is closest to verbal. it depends on education & experience. remains stable through old age.
3 Fluid Intelligence
Involves adaptive an new learning capabilities, related to mental nonverbal operation and processes, increases in strength and peaks after adolescents, and then begins gradual and slow degeneration. Decreases over time. Closest to performance. ability to solve problems,
4 WAIS-IV percentile rankings
Interpret the Full Scale IQ and percentile rankings

Standard scores Scale Scores Rankings
130 and above 17+ very superior
120 - 129 15-16 superior
110 - 119 13-14 high average
90 - 109 8-12 average
80 - 89 7-6 low average
70 - 79 5-4 borderline
69 and below =<3 extremely low

Standard score MEAN: 100 SD: 15
Scale Score MEAN: 10 SD: 3 (sub-tests)
T-Score MEAN: 50 SD: 10
raw score: sum of correct answers.
standard score: based on standard population so we can compare with others same age.
IQ: mental age / Chronological age X 100
5 composite scores
VCI=Verbal Comprehension Index (4 scales)
PRI=Perceptual Reasoning Index (5 Scales)
WMI=Working Memory Index (3 Scales)
PSI= Processing Speed Index (3 Scales )
FSIQ= Full Scale Intelligence Quotient. Based on 10 scales. Overall current level of cognitive ability
3 VCI subtests +3 PRI subtests

GAI is used when examiners want to calculate a summary score that does NOT include the working memory or processing speed. Must met two conditions
1. too much variability among 4 indexes
2. Standard scores on the 2 scales differ by less than 1.5 SD.
7 Discrepancies
If there are 1 or 2 discrepancies and one of them is VCI-PRI or if there are at least 3 discrepancies (even if not VCI-PRI you would say "the current measure of global capacity is NOT a true and reliable measure of the client's current cognitive functioning"

If only 1 or 2 discrepancies and they are not VCI-PRI then you would say "The current measure of global capacity is a true and reliable measure of the client's current cognitive functioning.
8 Determining Strengths and Weakness
If the absolute value of the difference is greater than the critical value (.05) then YES there is a significant difference

To determine if this significant difference is a strength or weakness: See if actual number for the difference is negative (-) or positive (+). If it is negative (-) it is a weakness and positive (+)it is a strength.
17 Similarities (VCI)
-Measure of verbal concept formation and reasoning
-Involves: crystallized intelligence, abstract reasoning, auditory comprehension, memory
-Also involves: associative and categorical thinking, distinction between nonessential and essential features, verbal expression
18 Vocabulary (VCI)
-Word knowledge and verbal concept formation
-Measure of examinees crystallized intelligence, fund of knowledge, learning ability, long-term memory, and degree of language development
-Other abilities used include auditory comprehension and verbal expression
19 Information (VCI)
-Measure ability to acquire, retain, and retrieve general factual knowledge
-Also involves: crystallized intelligence and long-term memory
-Other skills include verbal perception, verbal comprehension, and verbal expression
20 Comprehension (VCI)
-Measures verbal reasoning and conceptualization, verbal comprehension and expression, ability to evaluate and use past experience, and ability to demonstrate practical knowledge and judgment
-Also involves crystallized intelligence, knowledge of conventional standards of behavior, social judgment, long-term memory, and common sense
31 Block Design (PRI)
-Measures ability to analyze and synthesize abstract visual stimuli
-Also involves nonverbal concept formation and reasoning, broad visual intelligence, fluid intelligence, visual perception and organization, simultaneous processing, visual-motor coordination, learning, and the ability to separate figure-ground in visual stimuli
32 Matrix Reasoning (PRI)
Generally measures visual/spatial organization
Pattern recognition
Analogic reasoning
Serial reasoning
Perceptual reasoning
Spatial ability
33 Picture Completion (PRI)
Measures visual perception and organization, concentration to detail, visual recognition of essential details of objects
34 Visual Puzzles (PRI)
Nonverbal reasoning
Ability to analyze and synthesize abstract visual stimuli
Fluid intelligence
Ability to anticipate relationships among parts
35 Figure Weights (PRI)
-Emphasis on quantitative reasoning
-Assesses Visual perception and organization, concentration, and visual recognition of essential details of objects
43 Digit Span (WMI)
-Forward involves rote learning and memory, attention, encoding, and auditory processing
-Backward involves working memory, transformation of information, mental manipulation, and visuospatial imaging
-Sequencing is similar to other tasks that are designed to measure working memory and mental manipulation
44 Arithmatic (WMI)
-Measures mental manipulation, concentration, attention, short and long-term memory, numerical reasoning ability and mental alertness
-May also involve: sequential processing, fluid, quantitative, and logical reasoning, and quantitative knowledge
45 Letter-Number Sequencing (WMI)
-Involves sequential processing, mental manipulation, attention, concentration, memory span, short-term auditory memory
-May also involve info processing, cognitive flexibility, and fluid intelligence
52 Symbol Search (PSI)
-Measure of processing speed, short-term visual memory, visual-motor coordination, cognitive flexibility, visual discrimination, psychomotor speed, speed of mental operation, attention, and concentration
-May also involve auditory comprehension, perceptual organization, fluid intelligence, and planning and learning ability
One of the most important uses for this subtest is score comparison with Coding
-Allows pulling out fine motor (graphomotor) speed from mental processing speed
53 Coding (PSI)
-Measures short-term visual memory, learning ability, psychomotor speed, visual perception, visual-motor coordination, visual scanning ability, cognitive flexibility, attention, concentration, and motivation
-May also involve visual sequential processing and fluid intelligence
54 Cancellation (PSI)
-Measures processing speed, visual selective attention, vigilance, perceptual speed, and visual-motor ability
-In neuropsych settings, cancellation tasks commonly used as measures of visual neglect, response inhibition, and motor perseveration
15 VCI Cognitive Capacities Primary
Retrieval of verbal information from long-term storage
retrieval of word meanings (Vocabulary)
retrieval of facts from various content areas (Information)
Reasoning with orally presented verbal information
reasoning with conceptually related words (Similarities)
reasoning with real-world cause-effect relationships (Comprehension)
16 VCI Cognitive Capacities Secondary
Auditory Acuity
Auditory Attention
Auditory Discrimination
Auditory Comprehension (Receptive Language)
Auditory Processing Speed
Initial Registration of auditorily presented verbal information
Working Memory applied with auditorily presented verbal information
Expressive Language Production
Executive Function cueing and directing of receipt of input, internal processing of
input, and production of responses
42 WMI Cognitive Capacities Primary
Primary Capacities Targeted for Assessment
Initial registration of stimuli
Mental Manipulation of stimuli
29 PRI Cognitive Capacities Primary
Reasoning with visually presented nonverbal stimuli
reasoning with visual quantitative information (Figure Weights)
reasoning with conceptually-related concrete visual stimuli
reasoning with conceptually-related abstract visual stimuli
reasoning about how to integrate visual elements to create a model
30 PRI Cognitive Capacities Secondary
Visual Acuity
Visual Discrimination
Visual Processing Speed
Initial registration of nonverbal visual stimuli
Working memory applied with nonverbal visual stimuli
Executive Function cueing and directing of receipt of input, internal processing,
and production of responses
41 WMI Cognitive Capacities Secondary
Auditory discrimination
Attention to auditory stimuli
Auditory processing speed
Mental processing speed
Retrieval of verbal information from long-term storage
Organization/sequencing ability
Math skills
Expressive language ability
Executive Function cueing and directing of receipt of input, internal processing,
and production of responses
50 PSI Cognitive Capacities Primary
Visual processing speed
Motor processing speed
Visual-motor processing speed
51 PSI Cognitive Capacities Secondary
Visual perception
Visual discrimination
Attention to visual details
Organization ability/skills
Graphomotor ability/skill
Use of working memory with visual stimuli
Language representation of visual stimuli
Executive Function cueing and directing of receipt of input, internal processing,
and production of responses
65 CHC Theory
Fluid intelligence/reasoning (Gf)
Crystallized intelligence/knowledge (Gc)
Visual-spatial abilities (Gv)
Auditory processing (Ga)
Short-term memory (Gsm)
Cognitive processing speed (Gs)
Decision/reaction time or speed (Gt)
Quantitative knowledge (Gq)
Reading/writing (Grw)
Long-term storage and retrieval (Glr)
66 (Gf)
Fluid intelligence/reasoning:
-The use of deliberate and controlled mental operations to solve novel on the spot problems (i.e., tasks that cannot be performed automatically).
-ability to hold and manipulate information in memory
67 (Gc)
-Crystallized intelligence/knowledge: Can be thought of as the intelligence of the culture that is incorporated by individuals through a process of acculturation.
-Gc is typically described as a person's wealth (breadth and depth) of acquired knowledge of the language, information and concepts of specific a culture, and/or the application of this knowledge.
-ability to reason w/ previously learned info
68 (Gv)
Visual-spatial abilities:
-The ability to generate, retain, retrieve, and transform well-structured visual images.
-the generation, storage, retrieval and transformation (e.g., mentally reverse or rotate shapes in space) of visual images.
-ability to reason using visual stimuli
69 (Ga)
Auditory processing:
-abilities that depend on sound as input and on the functioning of our hearing apparatus
-the extent an individual can cognitively control the perception of auditory information
-the ability to analyze, manipulate, comprehend and synthesize sound elements, groups of sounds, or sound patterns.
70 (Gsm)
Short-term memory:
-The ability to apprehend and maintain awareness of elements of information in the immediate situation (events that occurred in the last minute or so).
71 (Gs)
Cognitive processing speed:
-The ability to automatically and fluently perform relatively easy or over-learned cognitive tasks, especially when high mental efficiency (i.e., attention and focused concentration) is required.
-Perform simple, clerical-type tasks quickly
72 (Gt)
Decision/reaction time or speed:
-The ability to react and/or make decisions quickly in response to simple stimuli.
73 (Gq)
Quantitative knowledge:
-A person's wealth (breadth and depth) of acquired store of declarative and procedural quantitative knowledge.
74 (Grw)
-A person's wealth (breadth and depth) of acquired store of declarative and procedural reading and writing skills and knowledge. --Grw includes both basic skills (e.g., reading and spelling of single words) and the ability to read and write complex connected discourse (e.g., reading comprehension)
75 (Glr)
Long-term storage and retrieval:
-The ability to store and consolidate new information in long-term memory and later fluently retrieve the stored information (e.g., concepts, ideas, items, names) over hours, days, months, years.
-concerned with retrieving stored facts, and the reconstruction of material based on stored rules.
76 CPI
Cognitive Proficiency Index:
-Uses the WMI and PSI indexes to compute a score that reflect speed and motor control
55 Subtest deficits in Brain injured patients:
There is no single pattern/profile for brain injured patients.
In general, a way to understand brain damage is to compare scores as compared to their SES, age, education, occupation, etc.
Left Hemisphere damage is associated with lower verbal abilities (lower VCI) and right hemisphere damage is associated with lower non-verbal abilities (PRI).
A general finding is that inter subtest scatter likely occurs with focal lesions or recent origin and a generally lowering of all abilities is often associated with chronic lesions or diffuse degenerating diseases.
Working Memory and Perceptual Reasoning were lowered among the brain-injured groups. This indicates the decrease in processing speeds in brain injured populations (seen with both Alzheimer's and TBI's)
Processing Speed Index Scores, Block Design (right and left hemisphere), Digit Span (Left Hem), Arithmetic (left-hem)
Vocabulary, Information, and Picture Completion are noted to be a general estimate of premorbid level of functioning. However, Information and Vocabulary were lowered with left-temporal damage.
Picture Completion deficits may indicate visual agnosia (difficulties recognizing objects) and visual neglect may be present.
Similarities can be lowered with left-frontal lesions
Qualitative errors such as poor judgment and impulsivity, concrete thoughts, clang responses, etc. may provide data to help understand the deficits.
Increased performance with multiple choice options may indicate retrieval difficulties.
Backwards sequencing tasks are more sensitive to brain injury deficits.
• Brown ADD model: small inverse relationship with WMI (mostly related to effort issues and need sustained effort to perform these tests).
• Cancellation mostly highly and consistently correlated with Brown ADD as it requires inhibitory control and ADHD includes impulsivity. See table 5. 14
• PSI and WMI more affected than VCI and PRI effect sizes (normal vs. ADHD groups).
• Saw sig differences in Coding, Arithmetic, Matrix Reasoning, and Figure Weights subtests (working memory deficits in fluid memory tasks).
57 Moderate to Severe TBI --WAIS-IV
• Evaluated by comparing to D-KEFS (Table 5.16)
• Processing speed (PSI) significantly impacted
• Symbol Search, Coding, and Cancellation (loss of ability to switch tasks and rack relevant data) had high correlations with D-KEFS scores
• Highly variable depending on type of injury as may affect language, attention, working memory, processing speed, visual perception and processing, and abstract reasoning.
• TBI vs. control large effect sizes for PRI, PSI, and FSIQ. PSI had largest effect sizes. VCI and WMI had moderate effects.
• Subtests most strongly affected included Symbol Search, Figure Weights, Visual Puzzles, Arithmetic, and Matrix Reasoning. Moderate effects for Block Design, Digit Span, Information, Coding, Letter-Number Sequencing, Cancellation, and Picture Completion.
• Verbal Abilities are relatively preserved.
58 Autism (excluded IQ below 60) -- WAIS-IV
• Four times higher rates for males vs. females
• Females tend to have lower IQ with Autism
• lower mean scores of all composites, especially PSI, FSIQ, and VCI (verbal and process task deficits but intact perceptual task performance).
• Subtest evaluation indicated deficits in Symbol Search, Vocabulary, Comprehension, Similarities, and Coding. Highest scores were seen on Matrix reasoning, Visual Puzzles, Block Design, and Figure Weights indicating better performance on perceptual tasks.
59 Asperger's Disorder (excluded if 2 SD below mean)
• Lower mean scores of on WMI and FSIQ (lower processing speed performance as compared to other areas of processing).
• Subtest evaluation indicated deficits in Coding, Cancellation, and Symbol Search (speed subtests). Moderate effects for Comprehension (impairment in social interactions, judgment, and conventions of behavior).
60 Gifted Groups --WAIS-IV
(2 SD above average or MENSA/Gifted Services)
• Tend to score higher in Verbal, Nonverbal, and overall cognitive ability as compared to general population.
• Some have large discrepancies between verbal and nonverbal scores
• Lowest scores found on Cancellation and Symbol Search Subtests (processing speed subtests).
• 77% of intellectually gifted had FSIQ of 120 + verses 18% of matched control groups.
61 Lower IQ Groups--WAIS-IV
• In normal distribution of IQ, 2.2 % obtain IQ scores lower than 2 SD's below mean but 2.5 to 3.0 % prevalence of intellectual disability noted in GP.
• Tend to see less variability in scores.
• Mild severity subgroup scores ranged from 58.5 (FSIQ) to 65.9 (VCI) and all scores sig. lower than control group. SD's for composite scores ranged from 6.3 (VCI) to 12.6 (PSI).
• Moderate severity group scores ranged from 48.2 (FSIQ) to 56.8 (VCI). SD's for composite scores ranged from 4.6 (WMI) to 7.3 (PSI).
• Borderline Intelligence ranged from 72.7 (FSIQ) to 80.9 (PSI) and all means were sig. lower than control groups. SD's for composite scores ranged from 7.2 (FSIQ) to 11.1 (PSI). Sig. deficits on Block Design, Matrix Reasoning, Vocabulary, and Arithmetic.
62 Learning Disorders -- reading -- WAIS-IV
• Reading Disorders: lower mean scores of all composites, especially WMI. Moderate effects for VCI and FSIQ. Relationship appears to exist between reading achievement and difficulties with tasks requiring short-term or working memory.
• Subtest evaluation indicated deficits in Letter-Number Sequencing, Arithmetic (working memory issues), and Vocabulary, which may indicate lack of general fund of info related to reading deficits.
63 Learning Disorders -- Math --WAIS-IV
• Mathematics Disorders: lower mean scores of all composites, especially WMI (contains math questions), PRI, and FSIQ. Relationship appears to exist between reading achievement and difficulties with tasks requiring short-term or working memory.
• Subtest evaluation indicated deficits in Arithmetic, Letter-Number Sequencing, and Figure Weights indicating an association between working memory and math learning disorders.
64 Depression-alzheimer's -- WAIS-IV
• Small effect size for PSI
• Lowered processing speed in older adults with depression.
• Small effect sizes for Visual Puzzles, Coding, Figure Weights, and Cancellation (all related to processing speed).
• Alzheimer's Disorder
• Most common form of dementia in older adults.
• Scores ranged from 76.6 (PSI) to 86.2 (VCI) and all scores were significantly lower than control group scores.
• Lower subtest means for all subtests with largest effects seen with Symbol Search, Information, Coding, and Arithmetic. Digit Span Sequencing was also significantly deficit (sensitivity to digit ordering tasks found in Alzheimer's Dementia).
• Showed lower performance scales than controls.
Verbal Comprehension Index: measures Gc verbal conceptualization abilities, knowledge and expression.

Core Subtest (Vocabulary, Similarities, and Information) Supplemental (Comprehension)

VCI is a measure of verbal abilities and the understanding of factual knowledge, meaning of words, and ability to express materials in words. This subtest taps: abstract information processing, verbal memory abilities, verbal fluency, and the amount a person has learned from their educational background.
Person with high VCI scores tends to have a verbally fluent presentation, may work in verbally fluent occupations, easily constructs sentences, and understands spoken language.
Person with low VCI scores may have difficulties communicating orally with others, may have work finding difficulties to express their thoughts, and may have low interest in academic pursuits.
This subtest is most influenced by cultural factors.
If VCI > PRI by at least 9 points = tendency toward overachievement, psychomotor retardation related to depression, difficulties working with practical tasks, nonverbal deficits, a high level of education, poor visual-motor integration, or a quick impulsive style.
Similarities: Measures verbal concept formation and abstract reasoning of routine activities. Long-term memory is also a component of this subtest. High levels of abstraction are noted if subjects successfully answer the last series of questions. High scores could indicate high insight and introspection abilities that could indicate a favorable psychotherapy prognosis.
Low scores could indicate a psychotic disorder, rigid or inflexible thought styles, poor abstraction abilities, literalness, and memory loss conditions.
High scores tend to indicate the presence of intellectualizing abilities and verbal concept formation.
This subtest is most sensitive to left-hemisphere lesions (especially left temporal or left frontal region) deficits in adults.
Vocabulary: Measures word knowledge, language development, language skills and verbal learning ability, educational background, ranges of ideas and experiences, and general verbal intelligence. This test also measures long-term memory and concept formation. It is known as a measure of verbal sophistication and effects and level of education.
It is the most reliable Verbal Comprehension subtest and is the best predictor of general intelligence. This subtest tends to be resistant to neurological damage and psychological impairment. Because of this, it is considered a measure of premorbid functioning.
This tends to be a stable subtest over age unless a person is more focused on visual-skills development.
High scores: high general knowledge, good recall of past knowledge, wide range of interests, high needs for achievement, and a good fund of information. In clinical populations it may indicate compulsive and intellectualizing patterns.
Low scores: Limited educational experiences, poor language development, lack of English language mastery, poor motivation, or low general intelligence.
Information: Measures general factual knowledge, alertness to routine events, long-term memory, data learned in school, and intellectual curiosity levels. This measures general alertness to one's environment and remote memory
This subtest is also resistant to neurologic al deficits or psychological disturbances and tends to be a relatively stable subtest over the lifespan. It tends to be correlated with general intelligence and educational levels. It does not tend to be affect by anxiety and fatigue as are test such as Arithmetic, Coding, and Block Design.
This subtest has been correlated with college GPA levels and college aptitude test scores.
High scores: good long-term memory, well-developed cultural background, an interest in school, strong verbal abilities, use of intellectualizism as a defense mechanism, and cultural interests.
Low scores: superfical interests, cultural deprivation, lack of curiosity, lack of acculturation to US values.
If a person fails earlier questions but correctly responds to more difficult questions it may indicate data retrieval, malingering, or poor motivation.
Comprehension: Demonstration of conventional behaviors, practical knowledge, ability to learn from past experiences and knowledge, generalization, abstract thinking abilities, social judgment, common sense, and reality awareness. This subtest has also been noted to relate the development of a conscience and problem solving abilities.
If comprehension is significantly below Information then the patient may not be effectively using his/her knowledge gained through education and experience.
If a person fails earlier questions but correctly responds to more difficult questions it may indicate impaired judgment.
Emotional responsiveness is also a factor to be subjectively/qualitatively evaluated during this subtest as highly analytical responders may avoid emotions in this subtest.
High scores: Social compliance, good judgment, emotionally relevant of information, and reality awareness.
Low scores: (especially if scores 4 or more points lower than Vocabulary) indicate poor judgment, hostility towards their environment, impulsiveness, or possible antisocial tendencies, idiosyncratic thinking, or psychosis.
Perceptual Reasoning Index/Subtests (Block Design, Matrix Reasoning, and Visual Puzzles)
Perceptual Reasoning Index: measures nonverbal thinking and visual-motor coordination
This index measures nonverbal, fluid reasoning skills. It also measures a person's attention to details, ability to work in concrete situations, use of visuospatial information, and integration of stimuli and motor skills. This subtest is less effected by level of education and relates to practical skills such as reading a map, finding objects, drawing a design, correctly assembling objects, etc.
Low scores: difficulties following spatial directions, estimating distances, or repairing broken objects.
If PRI > VCI by at least 9 points this may indicate superior perceptual organization skills, low academic achievement/focus, acting out behavior, being a doer rather than a thinker, language deficits, low socioeconomic background, poorly developed auditory/conceptual processing skills, or developed problems solving skills noted based on accumulated knowledge.
Block Design: Measures ability to identify parts into a whole component, spatial abilities, nonverbal concept formulation, perceptual organization, visuomotor coordination, shifting frame of reference, concentration abilities, and perceptual speed.
Correlates high with general intelligence and is stable over lifetime but can be affected by depression and organic impairment.
Processing styles and behavioral observations can be made in this subtest in areas such as hand preference, coordination, speed of processing, impulsiveness under frustration, holistic vs. sequential problem solving styles, or impulsivity with tasks.
If a client places blocks outside the perimeters of the designs it indicates poor visuospatial skills.
It is minimally affected by culture or educational backgrounds.
Deficits could indicate right-hemisphere brain damage, especially right parietal lesions where patients may distort designs perceive aspects or become disoriented in their experience with the blocks. Left-lesion patients are not as likely to have poor block design scores but they may have design simplification, confusion or a concrete approach to design reproduction.
Low scores: may indicate Alzheimer's disorder as it is sensitive to the early phases of the disease. Low scores suggest poor perceptual abilities, difficulties with visual integration, and maintaining sustained effort.
High scores: good visuospatial skills, visuomotor skills, concentration, and nonverbal concept formation.
Matrix Reasoning: Visual processing and organization, wholes into parts analysis skills, and abstract reasoning. It is not timed so it is useful for older clients or those who are cautious in their problem solving approach.
High scores: good nonverbal abstract reasoning abilities, simultaneous visual processing skills, and visual information processing skills.
Low scores: Low visual concept formation, poor or rigid visual reasoning, or poor concentration which may be related to negativism.
Visual Puzzles: Visual recognition, parts to whole perceptions, fluid reasoning, sustained visual effort, visual spatial reasoning. It is solely based on visual reasoning.
High scores: good nonverbal reasoning and visuospatial integration, and ability to concentration.
Low scores: Problems integrating visuospatial information, visual neglect, or problems with concentration.
Figure Weights: Nonverbal test of mathematical reasoning involving quantitative and analytical reasoning to induce or deduce logical solutions. It also measures ability to sustain motivation and effort.
High scores: Good nonverbal organization of data and quantitative reasoning and excellent concentration.
Low scores: poor nonverbal quantitative reasoning skills or poor concentration.
If Figure Weights = Arithmetic it indicates quantitative abilities are equal for both verbal and nonverbal information.
If Arithmetic is > Figure Weights by at least 3 points = verbal quantitative abilities are better developed than nonverbal quantitative abilities.
Picture Completion: Visual concentration, nonverbal test of general information, and relates to a patient's experience with their culture.
If a person is not acculturated to US culture they may make errors because of lack of experiences rather than lack of intelligence.
People who are unable to emotionally detached from the stimuli (passive, dependent personalities) may make errors. (there's nobody holding the pitcher).
High scores: recognize essential visual information, visual acuity, attentive/alert.
Low scores: poor concentration inadequate visual organization and may indicate impulsiveness.
Working Memory Index/Subtests (Digit Span, Arithmetic, Letter-Number Sequencing)

Working Memory Index: measures number ability and sequential processing. It also measures attention, concentration, but also anxiety, sequencing abilities, planning skills and executive functioning.
More complex and controversial than other index measures. Relates to concentration, short-term memory, and attention. It does not just measure memory and must be interpreted cautiously. You should never indicate that if a person does well they have good memory and vice versa, rather, auditory aspects of memory and sequencing /executive functioning are measured. Motivation also impacts this index score.
High scores would indicate good recall for numbers, ability to follow sequential instructions, ability to concentrate without distraction, and may be able to simultaneously complete tasks.
Low scores could indicate difficulties paying attention, following a series of instructions, or being able to do simultaneous tasks. This measure is also sensitive to the effects of anxiety.
Digit Span: Immediate recall, concentration, attention auditory sequencing, and ability to reverse thoughts.
Digit forward is considered resistant to deterioration.
High scores: good auditory memory, unimpaired attention, and free of anxiety.
Low scores: difficulties concentrating on tasks or anxiety. Differences between digits forward vs. backwards may indicate organic deficit.
Arithmetic: computational skills, auditory short-term memory, ability to sequence information, school learning, concentration, logical reasoning, abstraction for numerical concepts.
Anxiety may decrease performance, especially since it is timed.
Information + Arithmetic = School Achievement.
High scores: tend to be from higher SES, are obedient to teacher instructions, and have intellectualizing tendencies. Indicates alertness, concentration for tasks, and good short term auditory memory.
Low scores: May be antisocial and lack of desire to learn rules found in math, indicates poor mathematical reasoning, distractibility, poor concentration, anxiety,
Letter-Number Sequencing: Auditory short-term memory, concentration abilities, and ability to sequence data.
High score: good short-term memory, working memory, ability to sequence auditory information, and has persistence/concentration.
Low scores: Difficulties with auditory sequencing and poor short term auditory data recall. May also indicate poor attention, anxiety, impulsiveness, or poor motivation.
Processing Speed Index/Subtests (Symbol Search, Cancellation, and Coding)

Processing Speed Index: measures response speed with non-verbal tasks. It also measures fine motor coordination, motivation, visual and working memory and compulsiveness
Measures motor and mental speed when solving non-verbal problems. Planning, organizing, and developing problem solving strategies are also measured. Test taking attitudes and poor motivation can lower scores in this domain.
This domain is most sensitive to cognitive problems such as dementia, TBI, ADHD, and Learning Disorders.
As people age, this index tends to decline in 20's and a larger drop in mid 30's; whereas Verbal Comprehension is more resistant to the effects of aging. Among gifted groups, this tends to be the lowest index.
High scores: good problem solving skills, can read fast, have good memory for numerical recall and can identify items easily.
Low scores: May need extra time to learn tasks, may be slow readers, may be hesitant, and may have difficulties picking out objects. This can also indicate poor motor control and sensory acuity difficulties.
Coding: Measures psychomotor speed, clerical speed, visual short-term memory, ability to follow directions, ability to learn a new task, concentration, attention, and sequencing abilities. Specifically, to perform well on this test a client needs to have good recall for symbol-digit pairs and have intact psychomotor processing speed.
High scorers: excellent visuomotor abilities, capacity to learn new materials, and quick psychomotor processing.
Low scores: difficulties with visuomotor functioning, poor mental alertness, and difficulties with visual associated learning tasks.
Symbol Search: Information processing speed, planning, encoding information, learning, visuomotor coordination, and visual search speed are measured on this test.
High scores: can rapidly learn and integrate information, good visuomotor coordination, short-term visual memory, attention, concentration, and general learning abilities are measured.
Low scores: difficulties with visual-perceptual processing, poor motivation, anxiety, short term visual memory problems, perfectionistic, and obsessive problem-solving.

Cancellation: Perceptual recognition, speed and accuracy, attention, concentration, visuomotor coordination, perceptual scanning ability, and perceptual discrimination abilities.
High scores: good processing speed, attention, concentration, scanning abilities, and perceptual recognition.
Low scores: visual neglect, difficulties inhibiting responses, and motor perseveration may be present. Poor distractibility noted in ADHD and TBI may been noted on this subtest. Slow processing speeds, poor perceptual recognition, poor scanning abilities, and poor motivation.