Differences in Fingerspelling Praxis Performance Between Deaf Children with Autism and Deaf Typically Developing Children Between 5 and 14 Years of Age

Background:   Fingerspelling – spelling out English words using hands – is an important part of American Sign Language (ASL) acquired early on by deaf children (Padden, 1991). Fingerspelling is a complex motor skill requiring high-levels of praxis, the ability to perform complex movement sequences. Children need to learn a different handshape for each letter of the alphabet and produce these handshapes in the correct order to accurately produce a fingerspelled word. Some deaf children with Autism Spectrum Disorder (ASD) have been shown to acquire fingerspelling in ASL by 5 years of age (Shield & Meier, 2012). However, children with ASD demonstrate significant impairments in motor coordination and praxis (Jansiewicz et al, 2006, Mostofsky et al, 2006). Therefore, these impairments may affect fingerspelling performance in children with ASD.

Objectives: In the present study, we compared the fingerspelling abilities of deaf school-age children with and without autism using a range of spatio-temporal errors described in the praxis literature.  

Methods:   22 deaf children between 5 and 14 years of age (11 typically developing (TD) children and 11 children with ASD) were videotaped during a finger spelling task involving a set of 15 common words. Children in both groups were matched on age and nonverbal intelligence measured by the Test of Nonverbal Intelligence (TONI; Brown et al., 2010). A blinded and trained ASL signer coded all videos using a coding scheme based on the current praxis literature (Dewey et al., 2007). We evaluated the various spatio-temporal errors produced during the fingerspelling sequences for each word. Specifically, we coded the fingerspelling time and errors in pace, accuracy, sequence precision, movement modulation, and body part use. We also correlated praxis performance (time and total errors during finger spelling) with the children’s nonverbal intelligence and receptive language based on a standard ASL comprehension measure (Enns et al., 2013).

Results:   TD deaf children fingerspelled words more quickly (Mean (SD) - TD: 1.23 (0.43), ASD: 2.38 (0.98)) and produced fewer errors in pace (TD: 3.18 (4.45), ASD: 11.09 (7.76)), sequence precision (TD: 1.73 (1.42), ASD: 4.91 (4.16)), and body part use (TD: 0.09 (0.30), ASD: 3 (3.90)) compared to deaf children with ASD (pvalues < 0.05). We found that total praxis errors correlated strongly with receptive language abilities (Pearson’s r = -0.74) but not intelligence (Pearson’s r = -0.20) in children with ASD, with no clear correlations seen in TD children.

Conclusions: Our findings suggest that praxis errors during fingerspelling are three-fold in high-functioning deaf children with ASD compared to age- and IQ-matched TD deaf children. These findings add to the current body of literature on motor planning and coordination impairments of children with ASD by describing a novel research population. Our results highlight the persistent motor deficits in school-age children with ASD and a clear need for motor interventions in this population. The fingerspelling system of ASL, with its complex motor demands, provides a unique opportunity for motor intervention in deaf children with ASD.