Native Exposure to Sign Language Does Not Attenuate the Social-Cognitive Deficits of ASD
Objectives: To investigate the relationship between language, non-linguistic social cognition (ToM and visual perspective-taking), and non-linguistic spatial cognition (mental rotation) in a novel research population, native-signing children with ASD.
Methods: Sixteen native-signing children with a confirmed ASD diagnosis (12 male, 4 female; Mage = 9.91, SD = 2.43) and 18 typically-developing (TD) native-signing children (8 male, 10 female; Mage = 9.3, SD = 1.77) were tested. Groups were matched for chronological and mental age using the Test of Nonverbal Intelligence (TONI; Brown, Sherbenou, & Johnsen, 2010). Children were tested on the ASL Receptive Skills Test (ASL RST; Enns, Zimmer, Boudreault, Rabu, & Broszeit, 2013), two minimally-verbal social-cognitive tasks: false-belief (Pyers & Senghas, 2009) and visual perspective-taking, and a minimally-verbal mental rotation task (Martin, Senghas, & Pyers, 2013). All responses were coded by a trained coder fluent in ASL and blind to participant group.
Results: Native-signing children with ASD scored significantly lower than native-signing TD children on the receptive language task (ASD M = 85.6, SD = 10.9; TD M = 108.7, SD = 6.3; p <.001), false-belief ToM (ASD Maccuracy = 0.55, SD = 0.35, TD Maccuracy = 0.82, SD = 0.19; p = .01), and visual perspective-taking tasks (ASD Maccuracy = 0.24, SD = 0.4, TD Maccuracy = 0.71, SD = 0.42; p < .01). However, there was no significant group difference in mental rotation (ASD Maccuracy = 0.75, SD = 0.22, TD Maccuracy = 0.86, SD = 0.14; p = .23, ns).
Conclusions: Compared to TD deaf children, deaf children with ASD showed evidence of significant language, ToM, and visual perspective-taking delays, but intact mental rotation skills. Language delays in ASD are thus implicated in the development of social cognition, but not spatial cognition. These results fill gaps in the literature on the role of language in the development of social cognition, and provide additional evidence for deficits in language, ToM, and perspective-taking skills in ASD. We conclude that native exposure to sign is not sufficient to overcome the social-cognitive impairments implicated in ASD, and that signing children with ASD show a similar profile to speaking children with ASD.