Intellectual Dysfunction (‘Mental retardation’)
Intelligence is defined as the ability to comprehend ideas and their relationships and to reason about them.
Measurement of intelligence:
Many psychological testing methods are used in an attempt to quantify intelligence and developmental level – many have poor repeatability and do not allow for cultural and educational differences, motivation and effort. But, it is the only available method.
More common tests include:
• Wechsler Adult Intelligence Scale Revised (WAIS-R) – provides a verbal, nonverbal and an overall intelligence quotient (IQ)
• Wechsler Intelligence Scale for Children Revised (WISC-R) – for children aged 6-16.
• Stanford-Binet test – gives mental age (MA) and IQ values. More heavily weighted to verbal tests may underestimate MA and IQ in those with communication disorders
• Denver II – measures 4 areas (gross motor, fine motor, language, personal-social) – not an IQ test, but a screening tool for developmental assessment in young children