The Wechsler Preschool and Primary Scale of Intelligence (WPPSI) is a standardized assessment aimed to measure the cognitive development for children ages 2 years and 6 months to 7 years and 7 months. This version of the Wechsler intelligence test is currently in its fourth edition (often referred to as WPPSI-IV).
History of the WPPSI Test
While other versions of the Wechsler Intelligence Scale have been around since the 1940s, the WPPSI was introduced much more recently in 1967. The original version of this IQ test was designed for children in the age range of 4 to 6.5 years old. The first revision of the test came in the form of the WPPSI-R in 1989. This test expanded the age range to 3 years to 7 years 3 months and retained the original eleven subtests. Greater change took place with the updated version of the test in 2002 when additional subtests were adapted from the WISC-III test to test fluid reasoning and processing speed and included additional subtests for Coding & Symbol Search. The current version of the test has been in place since 2012.
The Wechsler Preschool and Primary Scale of Intelligence consists of 14 subtests split into three categories: core subtests, supplemental subtests and optional subtests. The core subtests are required to develop the three main index scores:
- Verbal
- Performance
- Full Scale IQ
The supplemental subtests are in place to provide additional information about a child’s cognitive functions and intellectual abilities, as well as acting as a replacement if certain subtests are inappropriate for certain children. The optional subtests are similar to the supplemental subtests except for the fact that they cannot be used to replace a core subtest.
WPPSI-IV Subtests
There are 14 total subtests included in the WPPSI. Children between the ages of 2 years and 6 months to 3 years and 11 months take the following five subtests:
- Block Design
- Information
- Object Assembly
- Picture Naming
- Receptive Vocabulary
Children that are between the ages of 4 and 7 years 7 months are administered the five subtests listed above and the nine additional subtests below:
- Coding
- Comprehension
- Matrix Reasoning
- Picture Completion
- Picture Concepts
- Similarities
- Symbol Search
- Vocabulary
- Word Reasoning
WPPSI IQ Test Scoring
When the test is complete the results from the individual subtests are used to develop Verbal, Performance, and Full Scale IQ scores along with a General Language Composite Score for children in each age band. For children who take all 14 subtests (aged 4 and older), a Processing Speed Quotient score can also be determined.
Children receive a score for each of the subtests and a score for overall intellectual ability. Each subtest provides a score from 1 to 19 with scores between 7 and 12 being average with subtest scaled scores having a mean of 10. Additionally, a percentile rank is provided for each area. This score indicates how the child did compared to other children of the same age. This would be reported as PR = 25, which means that the child scored as well or better than 25% of children the same age. The average for the overall intelligence is a score between 90 and 109 with a standard deviation of 15. Scores are determined by the child’s ability to give correct answers or successfully complete tasks that require the manipulation of objects to demonstrate a correct response, such as copying a pattern with blocks. Quotient and composite scores can be broken down into the following score report:
| Score | Performance Level |
|---|---|
| Below 70 | Extremely Low |
| 70-79 | Borderline |
| 80-89 | Low Average |
| 90-109 | Average |
| 110-119 | High Average |
| 120-129 | Superior |
| 130 and Over | Very Superior |
Test Reliability
The results of the WPPSI are considered to be reliable at an 89-95% confidence interval which is a high level of reliability for this type of evaluation. A trained professional follows an established protocol when giving the assessment to ensure that the results are valid and reliable. This includes a period of time to ensure that the child is comfortable with the examiner before the test begins. Overall, this assessment is the most widely accepted by professionals when it comes to evaluating the intellect of young children.