Why Do Deaf Children Score Differently on Performance vs. Motor-Reduced Nonverbal Intelligence Tests?

Abstract

Children who are deaf and hard of hearing (DC) and children with normal hearing (HC) have similar Performance IQs. However, DC score lower than HC on motor-reduced nonverbal intelligence tests (e.g., figural matrices tests). The difference between motor-reduced and motor-intensive (i.e., performance) nonverbal tests may be affected by psychomotor speed. This issue was investigated by comparing DC and HC on motor-intensive and motor-reduced nonverbal intelligence tests and on tests of psychomotor speed. Results show similar WISC-III Performance IQs for DC and HC and lower motor-reduced scores (from the Matrix Analogies Test-Short Form) for DC. This similar performance of HC and DC on an experimental motor-intensive nonverbal test, and on psychomotor speed measures, suggests that speed does not influence intelligence test results. We suspect that impulsivity, not speed per se, leads to the difference between motor-intensive and motor-reduced nonverbal test scores.