Historically, clinicians have used the Wechsler scales with deaf individuals by basing their estimate of intelligence on the Performance Scales.
While this may provide an adequate estimate for typically functioning deaf individuals, the neuropsychologist must consider the fact that it represents only half of the test, and is thus vulnerable to significant under- or over-estimates of cognitive functioning in individuals with specific strengths and weaknesses.
Individuals with non verbal learning disabilities may test as cognitively impaired, while those with language disorders may have their deficits overlooked.