Measuring Intelligence

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• A Psychometric Test is a standardised measure of of a selected aspect of an individuals behaviour, used to identify individual differences in psychological functioning among people.

• Intelligence tests are standardised measures of a persons general mental ability.

Functions:

• Measure a selected aspect of an individuals intellectual functioning

• Provide a score to allow an individual to be compared with other people

• Allow predictions to be made about an individuals performance or behaviour

• Used by psychologists as part of an assessment process, either for a group of people or individuals

Types of Tests:

Intelligence test: Measures intellectual ability of an individual

Aptitude test: Measures specialised skills such as hand-eye coordination

Personality test: Measures traits, qualities, or behaviours that make up a persons individuality

Achievement test: Measures a person's learning, success, or accomplishment in a subject or task, such as school achievement

Creativity test: Measures original thinking and the person's capacity to problem solve in novel situations

Motivational test: Measures interest and drive of an individual

Diagnostic test: Measures psychopathology (psychological disorders) and learning deficits

Interest Inventories: Measures a person's preference for certain activities or subjects to help in career guidance

Neuropsychological Test: Measures brain functioning and damage

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Intelligence Quotient

• Scores for intelligence tests are usually standardised so that the median score is 100, with 68% of the population obtaining IQ scores between 85-115, and 90% obtaining scores between 70-130.

• If a person has an IQ of 115, it means they answered 115 questions correctly - means they have an IQ of 15 above average score, and is in the 84th percentile.

• IQ scores are based upon deviations from the average score; how far their score differed from the average intelligence of the population.

• Average IQ is within one SD (15 IQ points) of the average IQ score (100 points)

• Two of the most commonly used intelligence tests are the Stanford-Binet intelligence scales and the Wechsler intelligence scales for adults (WAIS-IV) and children (WISC-IV).

Stanford-Binet Intelligence Scales

• Originally designed in 1905 by French physiologist Alfred Binet.

• Revised in 1916 by Lewis Terman psychology professor at Stanford university.

•Designed to assess individuals according to age

• Starts by asking them questions for one age below them and then slowly works their way up the ages until they reach a level the person cannot answer

• Then computes the IQ by comparing the person's scores with the norms for their age.

• The mean IQ for each age is 100

• Provides a single IQ score and also scores for various aspects of intelligence:

- Fluid reasoning

- Knowledge

- Qualitative Processing

- Visual-spacial processing

- Working memory

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Wechsler's Intelligence Scales

• Designed in 1939 by David Wechsler, a psychologist at New York's Bellevue Hospital

• Provides a general IQ score plus scores for four separate aspects of intelligence

• Broken into 3 separate tests according to age:

1. Wechsler Adult Intelligence Scales (for 16+ years)

2. Wechsler Intelligence Scales for Children (for 6-17 years)

3. Wechsler Pre-School and Primary scale of Intelligence (for 2.5-7 years)

• Advantage of it being broken into (subject/category) sections is that is makes it possible for people to demonstrate their cognitive strengths and limitations

Categories:

1. Verbal Comprehension Index: Ability to process verbal information, think and reason with words and previously learned information

2. Perceptual Reasoning Index: Ability to think in visual images, to reason without the use of words, and to interpret visual material

3. Working Memory Index: Short term memory and attention

4. Processing Speed Index: Mental efficiency, including attention, concentration, short-term visual memory and the ability to perform simple, clerical-type tasks quickly