Leiter International Performance Scale
Leiter International Performance Scale or simply Leiter scale is an intelligence test in the form of a strict performance scale. It was designed for children and adolescents ages 2 to 18, although it can yield an intelligence quotient (IQ) and a measure of logical ability for all ages.
Leiter devised an experimental edition of the test in 1929 to assess the intelligence of those with hearing or speech impairment and with non English speaking examinees. This test purports to "provide a nonverbal measure of general intelligence by sampling a wide variety of functions from memory to nonverbal reasoning." A remarkable feature of the Leiter scale is that it can be administered completely without the use of oral language, including instructions, and requires no verbal response from the participant. Without any verbal subtests, the Leiter scale only measures nonverbal intelligence. Because of the exclusion of language, it claims to be more accurate than other tests when testing children who cannot or will not provide a verbal response. This includes children with any of these features: Non native speaking, autism, traumatic brain injury, speech impairment, and hearing problems.
The Leiter scale was mainly used as a nonverbal alternative to the Binet scale, which is verbally weighted. However, it is also used by researchers, and also very frequently by clinicians who assess the "intellectual function of children with pervasive developmental disorders."
The latest version of Leiter is called Leiter-R (Revised), revised in 1997. It has an age range of 2 years to 20 years and 11 months. Not all subtests are administered to every child. Although this scale does an excellent job as an "aid to clinical diagnosis in disabled children. . . the test user must exercise caution in interpreting. . . test results because the meaning of test scores requires more research."
The Leiter contains 20 subtests organized into four domains:
The four Reasoning subtests are:
- Sequential order
- Repeated patterns
- Design analogies
The six Visualization subtests are:
- Paper folding
- Figure rotation
- Picture context
- Form completion
The eight Memory subtests are:
- Memory span (Forward)
- Memory span (Backward)
- Immediate recognition
- Delayed recognition
- Associative memory
- Associative delayed memory
- Spatial memory
- Visual coding
The two Attention subtests are:
- Attention sustained (marking one kind of figures printed on a page with several different figures)
- Attention divided (observing a display and simultaneously sorting cards correctly)
- Kaplan, R. M., & Sacuzzo, D. P. (2010). Psychological Testing: Principles, Applications, & Issues, Eighth Edition. Belmont, CA: Wadsworth, Cengage Learning