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  » Types of Intelligence

  » Intelligence, Heredity, and Environment
        Evidence for Nature
        Evidence for Nurture
        Comments on Research

  » Neuropsychological Testing
        Normal Intelligence
        Abnormal Examination             and Brain Trauma

  » Spectroscopy Data

  » Disorders related to Intelligence

  »  Gender Differences
       Self-Estimated              Intelligence
       Anatomical Differences
       Gray vs. White Matter

  » Artificial Intelligence
        A Timeline of AI
        Ancient History of AI
        Modern History of AI
        The Future of AI

  » Age and Intelligence
        Areas of Function
        Effects of Lesions

  » References

Normal Intelligence

Normal intelligence can be measured using the WAIS (Wechsler Adult Intelligence Scale) neuropsychological test for ages 16 and older. The WAIS measures memory, knowledge, problem solving, calculation, abstract thinking, spatial orientation, planning, and speed of mental processing. This test is based on two scales: verbal and performance.

Verbal scales

1. General information and knowledge: 29 questions
2. Digit Span:  Participants are asked to repeat several sets of digits first in the same direction as said or forwards, and then backwards. This is a test of immediate auditory recall and level of distraction.
3. Vocabulary: The participant is asked to define 35 words that get progressively harder.  This is a measure of expressive word knowledge and correlates very highly with full scale IQ.
4. Arithmetic:  The participant is asked to solve 14 mental arithmetic brief story type problems. This tests overall distractibility as well as numerical reasoning.
5. Comprehension:
  This asks the participant to answer 16 questions which focus on issues of social awareness.
6. Similarities:
Participants are asked to find reasons for why two seemingly dissimilar items might actually be similar.

Performance WAIS scales

1. Picture Completion: The participant is presented with 20 pictures that all have one specific piece missing. This is a test of attention to fine detail.
2. Picture Arrangement:  The participant is shown 10 sets of small pictures that need to be arranged into a logical sequence following pattern.
3. Block Design: 
The participant is required to match sets of blocks together to match patterns on cards.
4. Digit Symbol:  A code is given for each number, and the participant is to copying the coding pattern respectively.
5. Object Assembly:
  The participant is to assemble four small jig-saw type puzzles.

General intelligence is measured from the total of verbal intelligence and performance intelligence scores to yield a full scale IQ.  The scores are tallied and the scores are classified into different ranges. The following are the classification of scores used by most neuropsychologists.

            130 and above   Very Superior

            120-129   Superior

            110-119   High Average

            90-109    Average

            80-89    Low Average

            70-79    Borderline

            69 and below   Extremely Low  

Additionally, this test is used to determine vocational ability, intellectual ability in the classroom, and to determine organic deficits.  The WAIS is the most widely used test for intelligence. 

Children’s intelligence can also be measured using a similar test called the Wechsler Intelligence Scale for Children (WISC).  The WISC can test children ages 7-16.  This test is used as a tool in school placement, in determining the presence of a learning disability or a developmental delay, in identifying giftedness, and in tracking intellectual development.


 Lower normal


 Upper normal






 Highly gifted


 Profoundly gifted

The test can also be used for children aged 3-7 years, and is called the Wechsler Pre-school and Primary Scale of Intelligence (WPPSI).

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