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Vanessa D’silva
Clinical Psychologist, Learning Disability Clinic, KEM Hospital
What Is Intelligence?
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Ability to adjust to different situations.
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Ability to learn.
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Ability to engage in abstract thinking.
Definition By Wechsler
“The aggregate or global capacity of the individual
to act purposefully, think rationally and deal
effectively with the environment.”
Definition
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Aggregate and Global implies it is revealed by an
individual behaviour as a whole.
Purposeful implies that intelligent behaviour is goal
directed which is based on drives and incentives.
Theories Of Intelligence
Spearman’s ‘g’ Factor
Theory
Thurston’s Group
Factor Theory
Thorndike’s
Multifactor Theory
Spearman’s ‘g’ Factor
• All mental activity have the ‘g’ factor or the
mental ability.
• All individuals possess this, but in varying
degrees.
• The distinguishing feature of all mental tasks that
are high in ‘g’ is the ability to form abstract
linkages between apparently different things.
Spearmen’s ‘g’ Factor Theory
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Spearmen arrived at the concepts based on inter
correlations between different tests he administered
to his subjects. These were as follows:
 Analogies.
 Completion.
 Understanding
 Opposites.
 Instructions.
 Resemblances.
 Inferences.
Paragraphs.
Spearmen’s ‘g’ Factor Theory
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r = .55 Analogies and Opposites.
r = .32 Instructions and Resemblances.
However, the correlations were not perfect positive
correlations. This led Spearman to postulate the
existence of ‘s’ (specific) factors.
A specific factor is one that is characteristic of a
single mental task and is unique from other mental
tasks.
Thorndike’s Multifactor Theory
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Intelligence is composed of a multitude of highly
specific factors.
Two mental tasks will be highly correlated if they
shared these minute elements.
Thus Thorndike implicitly accepts the existence of
group factors.
Thorndike’s Multifactor Theory
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Thorndike developed the CAVD test i.e.
C
– Sentence Completion.
 A – Arithmetic Reasoning.
 V – Vocabulary.
 D – Following Directions.

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Each of the subtests measured different aspects of
Abstract Intelligence.
Significant
positive correlations were found
between subtests thus indirectly giving the ‘g’ factor.
Thurston’s Group Factor Theory
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According to Thurston mental action have in common
primary factors or group factors.
These primary factors are shared by some mental
tasks and not others.
They serve to bind mental activities into separate
groups and they are relatively pure in nature.
Thorndike’s Multifactor Theory
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He administered the following tests (Primary Mental
Abilities Test):
N – Number Fluency.
 W – Word Fluency.
 V – Verbal Comprehension.
 S – Spatial.
 M – Memory.
 R – Reasoning.
 P – Perceptual Speed.

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However, inter correlations were significant high positive
ones. This led Thurston to propose the existence of a
second order ‘g’ factor.
Conclusion
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All three theories ultimately arrive at considerable
agreement with each other.
Critics of such theories believe there no real
difference between ‘general’, ‘group’ and ‘specific’
factors.
These differences emerge simply because of the
number and nature of tests on which a factor
analysis is conducted.
DSM –IV TR Classification

IQ 71-84

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IQ 50 -55 to approx. 70

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Moderate Mental Retardation.
IQ 20-25 to approx. 35-40
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Mild Mental Retardation.
IQ 35-40 to approx. 50-55
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Borderline Intellectual Functioning.
Severe Mental Retardation.
IQ Below20-25

Profound Mental Retardation.
Wechsler’s IQ Classification
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IQ 90 – 110
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IQ 110-120
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Above Average Intelligence.
IQ 120-130
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Average Intelligence.
Superior Intelligence.
IQ 130 and above
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Very Superior Intelligence.
Salient Features Of IQ Tests
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Standardized instructions for test administration.
Time limit allotted to each items.
The item limit after which test is to be discontinued.
Evaluative criteria together with specimen answers.
Scheme of scoring.
Bonus scores to be given for rapid performance.
Wechsler’s Intelligence Scale For
Children By Dr M. Bhatt
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This scale includes
12 separate subtests.
Age 5+ to15+
It yields Verbal IQ,
Performance IQ
and Full Scale IQ.
Verbal Tests
• Information
• General
Comprehension
• Arithmetic
• Similarities
• Vocabulary
• Digit Span
Performance
Subtests
•
•
•
•
•
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Picture Completion
Picture Arrangement
Block Design
Object Assembly
Coding
Mazes
WISC Scoring
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Raw scores obtained for each subtest are converted
to Scaled Scores.
Scaled Scores are converted to Verbal IQ and
Performance IQ.
The sum of Verbal IQ and Performance IQ Scaled
Scores give the corresponding Full Scale IQ.
LD Features On The WISC
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The difference between Verbal IQ and Performance IQ
is 15 or greater it indicates presence of extraneous
factors.
Resulting Full Scale IQ obtained is considered not a true
indicator of intelligence.
Scores on the ACID profile lower than intra test average
i.e. the scores on Arithmetic, Information, Coding and
Digit Span.
WAIS-R Block Design Task
Seguin Form Board (SFB)
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Aim: The individual has to insert geometrical
shaped blocks into corresponding recesses as
quickly as possible.
Norms available from 3years to 20 years.
Used particularly for young children and
supplemented with other tests.
Advantages:
 Spontaneous
arousal in children.
 Amenable & brief.
 Valid ‘g’ obtained.
Kamat Binet Test Of Intelligence (KBI)
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The original test was the Stanford Binet scales.
This test was developed based on the concept of
age norm.
Kamat undertook a revision of the Stanford Binet
Scales to suit Indian conditions.
The tests has subtests from Age III to XXII.
Administering The KBI
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Begin with the tests of the year of the child.
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He/ She may pass on some but fail in few.
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Work upwards till the child fails on all items.
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Then work below the child’s chronological age until
all items are passed.
Scoring And Interpreting The KBI
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For each item passed the child earns a credit of
2 months, 4 months or 6 months depending on the
corresponding age.
IQ = Mental Age × 100
Chronological Age
The IQ thus obtained is classified.
Raven’s Progressive Matrices
Raven’s Progressive Matrices
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It is a test of observation and clear thinking.
Measures ability to form perceptual relations,
reason by analogy independent of language and
formal schooling.
It consists of 5 sets of 12 items each.
Each item contains a figure with a missing piece.
Norms are available for age 6 – 16.
Questions?
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Vanessa D’silva
Clinical Psychologist, Learning Disability Clinic, KEM Hospital