Participants

There were 29 children with reading disability (Poor Readers), 41 children with ASD, and 75 typically developing (TD) children recruited from the Boston area of the United States. After screening for data quality (see Image-data acquisition and analysis below) and matching for demographic characteristics, 64 children (19 Poor Readers, 25 children with ASD, and 20 TD children) ages 5-17 years were included in this study (Table 1). All children were native speakers of American English, right-handed, born at 32 or more weeks gestational age, had normal hearing and non-verbal cognitive ability, and no history of head injury or co-morbid psychiatric or neurological conditions, nor any genetic disorders associated with autism (e.g., fragile X syndrome). The three groups of children did not differ significantly on age (F_(2,61) = 0.91, P = 0.41), nonverbal IQ (Kaufman Brief Intelligence Test −2, F_(2,61) = 1.86, P = 0.16) (34), or gender ratio (K-W test, X² = 0.20, df = 2, P = 0.90). This study was approved by the Committee on the Use of Humans as Experimental Subjects (COUHES) at the Massachusetts Institute of Technology.

Group Characteristics

Note: Numbers outside and inside the bracket indicate mean and standard deviation, respectively. Statistical significance compared with TD:

Non-verbal IQ was measured by Kaufman Brief Intelligence Test Matrix subtest (34). Autism severity was measured with the standardized calibrated severity score, which ranges from 1 to 10 (38, 39). Word reading was measured with the average of the standard scores across four reading tests: word identification, word attack, sight word efficiency, and phonemic decoding proficiency. Sentence reading was measured with the standard score of the sentence reading fluency subtest of the Wookcock-Johnson 3 Test of Achievement (37). Language was measured with the core language score from CELF-4 (81) based on the sum of the scale scores of age-appropriate subtests, including concepts and following directions, recalling sentences, formulating sentences, word structure, word classes and word definitions.