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Leiter International Performance Scale – Third Edition (Leiter-3)

The Leiter International Performance Scale – Third Edition (Leiter-3; Roid, Miller, Pomplun, & Koch, 2013) is a standardized, individually administered, nonverbal test designed to assess cognitive functions in children, adolescents, and adults ages 3 to 75 years.


The Leiter-3 includes two groupings of subtests: the Cognitive Scales that measure fluid intelligence and the Attention and Memory Scales.

The Leiter-3 IQ score is not significantly impacted by language skills or by experiences (educational, social, family). The Leiter-3 is designed for use with individuals who are non- English-speaking, hearing impaired, speech impaired, cognitively delayed, or on the autism spectrum.


Author (yr) Age Range (yrs) Method of Administration/Format Approx. Time to Administer Subscales
Leiter International Performance Scale – Third Edition (Leiter-3) Roid, Miller Pomplun, & Koch (2013) 3–75+

Individually administered, norm-referenced measure of nonverbal cognition 10 subtests in 2 domains, Cognitive Scales (Fluid Intelligence) and Attention and Memory Scales.

Yields subtest and composite scores given in scaled scores, percentiles, and age equivalents. Also yields Growth Scores to indicate small improvements in people with significant cognitive disabilities.

20–45 min.

Sequential Order; Form Completion; Classification and Analogies; Figure-Ground; Matching/Repeated Patterns (optional); Forward Memory; Reverse Memory; Attention Sustained; Attention Divided; Nonverbal Stroop

Availability: Western Psychological Services,


<p>This table provides information regarding misconceptions surrounding cognitive assessment in general and is not specific to this assessment. </p>
Myth Reality
Full-scale IQ is a good description of a student’s cognitive ability. Students with autism typically demonstrate a scattered profile on comprehensive cognitive measures, performing better on tasks involving rote skills than on tasks involving problem solving, conceptual thinking, and social knowledge (Mayes & Calhoun, 2008; Meyer, 2001-2002).
If a student has an average IQ, an adaptive behavior measure is unnecessary. Although a student has an average IQ and may even be doing well academically, it does not mean that an adaptive measure is not necessary. Research indicates that many students with autism have deficits in communication, daily living skills, and socialization (Lee & Park, 2007; Myles et al., 2007). Klin and Volkmar (2000) stated that adaptive behavior is a critical area of planning for students with Asperger Syndrome (now referred to as autism spectrum disorder, Level 1) to facilitate transition from the school environment to work and community environments.
If a student demonstrates a well-below-average IQ, the student does not have any cognitive skills. A flat profile of skills may indicate difficulty accessing what the student knows. Formal cognitive assessments may not yield valuable information for assessing current level of functioning and needs for programming. In addition, students with autism spectrum disorder may not be able to generalize skills from the classroom setting to the testing environment, or the manner in which the information is being assessed may prohibit the child from demonstrating mastery of skills. For example, if the student has learned to perform a task in one way with a certain prompt and the assessment asks for it in a different way, the student may not be able to demonstrate knowledge of the skill.
Formal IQ is more valid than informal data from the classroom. Informal classroom data provide information about how the student functions on a daily basis. Analyzing formal and informal data to determine patterns of skills and learning is a key component of assessment (Hagiwara, 2001-2002). Informal data from the classroom may be more valuable than information gathered in a contrived one-on-one setting when determining programming for a student with autism spectrum disorder.


Author (yr) Sample Size Topic(s) Addressed Outcome
Tsatsanis, Dartnall, Cicchetti, Sparrow, Klin, & Volkmar (2003) 26 Concurrent validity

Researchers examined the relationship of the Leiter-R with the Leiter on a group of individuals with autism. The mean Leiter IQ score was not statistically different from the Leiter-R Brief IQ (t(21) = 1.37, p = .18) and Leiter IQ or Leiter Full IQ (t(21) = 0.37, p = .71).

Scores did not significantly differ between the Leiter-R Brief IQ and Leiter IQ (t(21) = 1.37, p = .

18) and Leiter R Full IQ (t(21) = .37, p = .71).

Classification into levels of functioning was examined. High agreement was found (kappa = .69, p < .0001)


Author (yr) Sample Size Topic(s) Addressed Outcome
​Grondhuis & Mulick (2013).​ 1,071 Validity

Differences in scores on the SB5 and Leiter-R were compared for a sample of children with autistic disorder and PDD-NOS. Results suggest that they are not equivalent measures of cognitive functioning when administered to individuals with ASD. As a result, depending on the measure used, misclassification of intellectual functioning could occur. Key results are summarized below.

A significant difference in scores were found between the Leiter-R and the SB5 (F(1,40) = 58.99, p < .001). The Leiter-R was, on average,

22.45 points higher than the SB5. The mean score on the Leiter-R was 87.11 while the mean on the SB5 was 64.66.

Diagnostic differences were found. Autistic disorder (Leiter-R mean IQ = 79.42; SB5 mean

= 59.12); PDD-NOS (Leiter-R mean = 96.61;

SB5 mean 71.52). Differences were not significant (F(1,40) = 3.16, p < .08). The discrepancy was significantly greater (Leiter-R IQ scores higher than SB5) in preschool children compared to those in grade school (F(1,40) = 4.88, p < .033.

Scores on the Nonverbal domain of the SB5 (mean = 70.40) were significantly lower than the Leiter-R full-scale composite (mean = 87.12); t(46) = 7.751, p <.001.

Scores on the Verbal domain of the SB5 (mean

= 62.00) was significantly lower than the Leiter- R total score (mean = 87.24); t(44) = 10.020, p