Sensitivity to probabilistic orthographic cues to lexical stress in adolescent speakers with autism spectrum disorder and typical peers.

Lexical stress refers to the opposition of strong and weak syllables within polysyllabic words and is a core feature of the English prosodic system. There are probabilistic cues to lexical stress present in English orthography. For example, most disyllabic English words ending with the letters "-ure" have first-syllable stress (e.g., "pasture", but note words such as "endure"), whereas most ending with "-ose" have second-syllable stress (e.g., "propose", but note examples such as "glucose"). Adult native speakers of English are sensitive to these probabilities during silent reading. During testing, they tend to assign first-syllable stress when reading a nonword such as "lenture" but second-syllable stress when reading "fostpose" (Arciuli & Cupples, 2006 ). Difficulties with prosody, including problems processing lexical stress, are a notable feature of autism spectrum disorder (ASD). The current study investigated the ability of adolescents with ASD (13-17 years of age) to show this sensitivity compared with a group of typically developing peers. Results indicated reduced sensitivity to probabilistic cues to lexical stress in the group with ASD. The implications of these findings are discussed.