Cognitive Development and the Psychological Evaluation
by Margaret B. Pulsifer, Ph.D.
Children with Down syndrome are frequently given a psychological evaluation as part of their multidisciplinary assessment. Formal psychological testing is usually administered beginning between 2 and 3 years of age or just prior to placement in preschool. The psychological evaluation is useful for four reasons: 1) to identify the strengths and weaknesses of a child and to identify developmental delays; 2) to determine the best intervention for the child; 3) to monitor the child's progress and the effectiveness of treatment; and 4) to give parents' insight about the child's abilities and what they can do for their child.
A psychological evaluation assesses cognitive abilities, adaptive skills, and behavior (temperament). Cognitive abilities, often called "intelligence," include skills involving verbal expression and comprehension, judgment, memory, and visual-motor skills. These abilities are assessed by using tasks such as naming pictures and defining words, answering common sense reasoning questions, repeating sentences, and manipulating blocks. Adaptive skills are the abilities children need to function daily in their world. These include communication and motor skills, self-help skills such as dressing and toilet training, and socialization skills like sharing and playing with peers. Information about adaptive skills comes mostly from parents' reports. Aspects of behavior that are addressed include activity level, attention span and cooperation. These are assessed both by direct observation and by reports from others (parents and teachers).
Cognitive abilities consist of a large number of specific skills. Intelligence tests assess a child's capabilities in many different areas, and the "IQ score" from these tests represent the child's overall performance in all areas. Children with identical IQ scores can have quite different cognitive profiles; for example, one child might be strong in verbal skills and weaker in memory, and another child might be strong in memory but weaker in verbal skills. Generally, the different cognitive skills develop fairly evenly, but some children show variability, or a particular strength or weakness in one area relative to the overall score. Children with Down syndrome often show variability, with verbal skills being less developed than visual-motor skills.
Scores from cognitive and adaptive tests are usually expressed as a "standard score," where most children in the general population will score between 80 and 120. A score below 70 indicates significant delay. When there is significant delay in both cognitive and adaptive skills, a diagnosis of mental retardation is made. Children with Down syndrome may show little delay in cognitive development until the end of the first year (Cicchetti & Beeghly, 1990). Thereafter, cognitive skills develop at a slower rate than in other children their age. Major delays often emerge at around 20 to 24 months of age, particularly within the area of language production (Nadel, 1988). By school age, children with Down syndrome most frequently score between 40 and 69 on cognitive tests, and have somewhat higher scores on measures of socialization and self-help skills. A common cognitive strength in children with Down syndrome is the ability to manipulate objects; common weaknesses are verbal skills and abstract reasoning.
A common reason of referral for developmental assessment with all children is behavior problems. The child's behavior is important both in his relationship to parents, teachers and peers, and also in terms of how he treats himself. Common behavior concerns in children with Down syndrome include short attention span, overactivity, and self-stimulating or repetitive behavior. One way of describing behavior is in terms of temperament, which is the behavioral style of the child, or the way the child reacts to the environment. Just as children vary in cognitive development, behavior and temperament are different in each child. Some children demonstrate regular patterns of eating and sleeping and adapt positively to change, while other children are irregular, tend to withdraw from new objects and are often irritable. Researchers have described temperament in children as either "easy," "slow-to-warm-up," or "difficult" (Thomas & Chess, 1977). The child's basic temperament is relatively stable, at least to 10 years of age. Children with Down syndrome are frequently stereotyped as being affectionate and "easy" in temperament. However, research indicates that temperament in children with Down syndrome is not uniform and that these children demonstrate a wide range of behavior concerns and temperament profiles (Cicchetti & Beeghly, 1990).
Many of the common tests used in psychological assessment with children with Down syndrome are listed below. Knowing the nature of the tests may help parents better understand the results of an evaluation. It is important to know that for any one child, the number and type of tests administered varies, depending on the child's developmental functioning and referral concerns. A complete psychological evaluation usually takes about 2 hours.
A. Tests of Cognitive Development or Intelligence
Bayley Scales of Infant Development (Mental Scale)
The Bayley Mental Scale is given to young children between the ages of 2 to 30 months. It follows the development of verbal communication, visual-motor problem solving skills, and object constancy and memory. Results are a developmental age-equivalent and a standard score called the Mental Development Index (MDI).
Stanford-Binet Intelligence Scale: Fourth Edition
The Stanford-Binet is used for ages 2 years through adulthood. It measures abilities in 4 areas, including verbal and visual reasoning, quantitative abilities, and short-term memory. Results are age-equivalent scores and a standard score, the Test Composite score ("IQ").
Wechsler Preschool and Primary Scale of Intelligence—Revised (WPPSI-R)
The WPPSI-R is used for ages 3 years through 7 years, 3 months. Skills assessed include verbal abilities (e.g., vocabulary) and visual reasoning skills (e.g., psychomotor speed). There are 3 standard scores: a Verbal IQ, a Performance IQ, and a Full Scale IQ.
Wechsler Intelligence Scale for Children - III (WISC-III)
The WISC-III is used for ages 6 years through 16 years, 11 months. It measures verbal abilities and visual reasoning skills similar to the WPPSI-R. There are 3 standard scores: Verbal IQ, Performance IQ, and a Full Scale IQ.
B. Tests of Specific Verbal Skills
Three tests are commonly used to assess specific verbal abilities:
The Expressive One-Word Picture Vocabulary Test —Revised assesses single word expressive language skills. The Peabody Picture Vocabulary Test —Revised assesses single word receptive language. Both of these tests are used for ages 2 years through adulthood. Both give standard scores and age-equivalent scores. The Receptive-Expressive Emergent Language Scale (REEL) is based on a parental interview. It is used to identify either expressive or receptive language delay from birth to 36 months of age. Results are age-equivalent scores.
C. Tests of Adaptive Skills
Adaptive skills are usually assessed with the Vineland Adaptive Behavior Scales. Results come from parental interview or teacher report. It is applicable for all ages. Results are age-equivalent scores and standard scores in four areas: communication, daily living, socialization and motor skills.
D. Assessment of Temperament and Behavioral Style
Parent questionnaire and direct observation are the major methods for assessing temperament characteristics in young children. The Carey Infant Temperament Questionnaire and the Toddler Temperament Questionnaire are two instruments completed by the parent that classify a child's temperament style into three groups: easy, difficult, and slow-to-warm-up. The Bayley Infant Behavior Record is completed by the psychologist, based on the child's behavior during the test administration.
E. Assessment of Academic Skills
School-aged children with Down syndrome are sometimes referred for evaluation to determine if their acquisition of academic skills is commensurate with cognitive abilities. Comparing academic abilities with cognitive skills can help identify relative learning problems. Brief screening of reading, spelling, and arithmetic skills can be performed by using the Wide Range Achievement Test-Revised. A more comprehensive evaluation can be conducted using the Woodcock-Johnson Psycho-Educational Battery—Tests of Academic Achievement. For both of these tests, the child's performance is expressed in standard scores, percentiles and grade-equivalents.
With the results of the child's psychological evaluation, the psychologist is able to provide information to parents and professionals to assist them in obtaining appropriate services. Recommendations by the psychologist are generally of four types: special education placement, specific services (e.g., speech and language therapy); behavior management at school or home; and referral to community services for parent support.
A federal law (Public Law 99-457), which went into effect in 1987, guarantees free public education to all children who need special education services. Children with Down syndrome qualify for early intervention services within the first months of life, because they have a high probability for later developmental delay. In Maryland, the Infants and Toddlers Program provides early intervention services for children to 3 years of age.
For school-aged children with Down syndrome, recommendations are made for education services that provide for the "least restrictive school environment" for each student. This is required by federal law (Public Law 94-142). The law also requires that each child be given an Individualized Education Plan (IEP), designed by the school in collaboration with the child's parents. Included in the IEP are the child's educational goals and required services, such as weekly physical therapy or a speech and language program. Both psychological re-evaluation and review of educational goals are required by law to monitor development and the appropriateness of the child's educational services.
The recommendations made from the psychological evaluation are primarily for the child. However, at times, parents may feel overwhelmed by their child's needs or behaviors. Information about community resources for parent support and guidance can be obtained through the Kennedy Krieger Social Work Department.
Cicchette, D., & Beeghly, M. (Eds.). (1990). Children with Down syndrome: A developmental perspective Cambridge: Cambridge University Press. Nadel, L. (Ed.). (1988).
The psychobiology of Down syndrome. Cambridge: MIT Press. Thomas, A., & Chess, S. (1977). Temperament and development. New York: Brunner/Mazel.
The article above is reproduced from the Down Syndrome Guide disseminated by the Down Syndrome Clinic at Kennedy Krieger Institute. In accordance with federal copyright restrictions, the contents of this booklet may not be reproduced by photocopying or any other means without written permission from the copyright holder. © 1999 George Capone, M.D.
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