McCarthy Scales of Children's Abilities are appropriate for children between the ages of two and one-half through eight and one-half years. This test battery is comprised of six sections: Verbal Scale, Perceptual-Performance Scale, Quantitative Scale, Memory Scale, Motor Scale, and General Cognitive Scale. The results do not provide an IQ score. Instead, a General Cognitive Index (GCI), which is similar but broader than a simple IQ, is computed. The McCarthy Scales also provide individual ability scores (verbal, non verbal reasoning, number aptitude, short-term memory, and coordination). The profile of these scores helps assessors to determine if learning problems are present in young children.
Bayley Scales of Infant Development are used to assess the development of infants and toddlers. Subjects may range in age between two months to three and one-half years of age. There are three sections: mental (including tests of recognition memory, object permanence, shape discrimination, attention, nonverbal communication and vocalization, receptive and expressive language), motor (including tests of gross and fine motor skills), and behavior (including tests of emotion and observed testing behavior). This test may be used with chronologically older children who are unable to take age-appropriate tests.
Tests measuring adaptive functioning are also used to establish how socially and emotionally mature a child is in comparison with his or her peers. Tests used for this purpose are described below.
The Woodcock-Johnson Scales of Independent Behavior is used to measure independent behavior in children.
The Vineland Adaptive Behavior Scale (VABS) is used to test social skills in individuals from birth to nineteen years of age. The test is not administered directly to the subject. Questions are directed to primary caretakers or other individuals who are familiar with the subject. The test contains four sections: Communication, Daily Living Skills, Socialization, and Motor Skills. An Adaptive Behavior Composite is determined through a combination of scores from each section of the test. There are separate norms available for individuals with mental retardation, behavior disorders, and physical handicaps.
The American Association on Mental Retardation Adaptive Behavior Scale is used to measure adaptive behaviors in people participating in residential and community settings. This test is often used to help determine and clarify goals for treatment plans.
Tests of IQ and adaptive functioning provide a sufficient basis for making a diagnosis of mental retardation. Other tests (e.g., neuropsychological tests) may provide further detail, which is not necessary for diagnosis. Information including test scores and medical and social history is gathered by a diagnosing physician and brought together to make the diagnosis. The test scores are weighed heavily but are not the sole basis for a diagnosis of mental retardation. If social observational data significantly contradict test results (e.g., if the child appears to be smarter or more adaptive than testing indicates), there is some leeway in how the diagnosis may be made.
The diagnosing physician needs to consider all of the data from tests, observations, and histories to see if the following formal criteria for mental retardation, as laid out in the DSM-IV, are met. If all formal criteria are met to that physician's satisfaction, then the diagnosis of mental retardation is made.
