Wechsler Pre-school and Primary Scale of Intelligence
The Wechsler Pre-school and Primary Scale of Intelligence (WPPSI) is used to assess the intelligence of children aged 2:6 years through 7:3 years. It provides composite scores that represent intellectual functioning in specified cognitive areas e.g. Verbal Intelligence Quotient (VIQ) and Performance Intelligence Quotient (PIQ) as well as providing a composite score that represents an overall Intelligence Quotient (IQ). Processing Speed is measured by two supplemental tasks.
The scores obtained represent estimates of a child’s true scores. That is, they reflect a child’s abilities combined with some degree of measurement error. The Confidence Interval gives the range of probable scores.
- Composite Scores are Standardised Scores - have an average of 100 and a standard deviation of 15. The average range is between 85 and 115.
- The Confidence Interval represents the band of scores where a child’s true score is likely to be 90% or 95% of the time.
Performance on subtests can be reported in a number of ways, these include:
Percentile – the number of children of a similar age out of 100 that a child would have performed as well as or better than. 50 is the average score.
Scaled Scores - lie between 1 and 19, with the average range between 7 and 13 (standard deviation of 3). These represent a child’s performance relative to same-age peers.
Age Equivalent – the age at which 50% of children will achieve at this level.
Not all tasks on the WPPSI need to be completed on every occasion. However, a sufficient number of subtests need to be completed to report upon an area of ability. The selection of tasks will vary according to each specific situation. The tasks that make up the WPPSI-III are detailed below:
Verbal Tasks
| Task | Ability Measured | Description of Task |
|---|---|---|
Information |
Crystallised intelligence, long-term memory, and the ability to retain and retrieve knowledge from school and the environment |
The child responds to a question either by pointing or verbally. Where no verbal response is required, the child responds by choosing a picture from four response choices. |
Vocabulary |
Word knowledge, verbal concept formation, fund of knowledge, learning ability, long-term memory and degree of language development |
Children are either shown a picture or told a word. For picture items the child names the pictures. For the verbal items the child gives a definition of the word read out loud to them. |
Word Reasoning |
Verbal Comprehension, analogic and general reasoning ability, the ability to integrate and synthesize different types of information, verbal abstraction, domain knowledge and the ability to generate alternative concepts |
The child is asked to identify the common concept being described in a series of increasingly specific clues |
Comprehension |
Verbal Reasoning, and conceptualisation, the ability to evaluate and utilise past experience, verbal comprehension and expressions and the ability to demonstrate practical information |
The child answers questions based on his or her understanding of general principles and social situations. |
Similarities |
Verbal reasoning and concept formation |
The child is read an incomplete sentence containing two concepts that share a common characteristic. The child is asked to complete the sentence by providing a response that reflects the shared characteristic. |
Receptive Vocabulary |
Comprehension of verbal directives, auditory and visual discrimination, auditory memory, auditory processing and the integration of visual perception and auditory input. |
The child looks at a group of four pictures and points to the one the examiner reads out loud to them. |
Picture Naming |
Expressive language ability, word retrieval from long-term memory and association of visual stimuli with language |
The child names a picture that is displayed. |
Performance Tasks
| Task | Ability Measured | Description of Task |
|---|---|---|
Block Design |
Analyse and synthesize abstract visual stimuli |
The child views a constructed model or a picture and uses one or two colour blocks to re-create the design within a specified time limit. |
Matrix Reasoning |
Fluid Intelligence |
The child looks at an incomplete matrix and selects the missing piece from 4 or 5 response options. |
Picture Concepts |
Abstract and categorical reasoning |
The child is presented with two or three rows of pictures and chooses one picture from each row to form a group with a common characteristic. |
Picture Completion |
Visual perception and organization, concentration and visual recognition of essential details of objects |
The child views a picture and points to or names the important part missing from the picture |
Object Assembly |
Visual-perceptual organization, integration and synthesis of part-whole relationships, nonverbal reasoning and trial-and-error learning |
The child is presented with a standardised configuration of puzzle pieces and allowed 90 seconds to fit the pieces together to form a meaningful whole. |
Processing Speed
| Tasks | Ability Measured | Description of Task |
|---|---|---|
Coding |
Processing speed, short-term memory, learning ability, visual perception, visual-motor coordination, visual scanning ability, cognitive flexibility, attention and motivation |
The child copies symbols that are paired with simple geometric shapes. Using a key, the child draws each symbol in its corresponding shape. |
Symbol Search |
Processing speed, short-term visual memory, visual-motor coordination, cognitive flexibility, visual discrimination and concentration |
The child scans a search group and indicates whether a target symbol appears in the search group by marking the appropriate symbol with a pencil. |
