This study examined grammatical judgment and production in 22 male participants with idiopathic autism spectrum disorder (ASD) who had a range of nonverbal IQ from 44 to 111 (mean = 72.23) and were between 9.42 and 16.75 years of age (mean = 13.45). Relationships between grammatical judgment and production and nonverbal IQ were examined. Participants completed the Test of Early Grammatical Impairment (TEGI) to describe relative strengths and weaknesses in their ability to judge and produce grammatical tense. Participants also completed the Leiter-R to assess the relationship between nonverbal IQ and grammatical judgment and production. Relative strengths were found across participants in judging correct use of subject-verb agreement in sentences, and correctly producing verbs that linked sentences (e.g., auxiliaries and copulas of be "Is she resting?"). Participants had the greatest difficulty judging the correctness of a sentence using a dropped verb tense marker (e.g., "He look happy now") and producing irregular verb tense markers. Nonverbal IQ did not contribute to the variance in performance on any tasks of grammaticality judgment or production. Grammatical markers that mark tense in past tense verbs as well as the production of auxiliary do may be an important focus of language intervention for boys with ASD.
Keywords: Autism spectrum disorder; grammar; intellectual disability; language comprehension; language production; vocabulary.