Can Timing Tasks Successfully Differentiate Children with ASD from Those with SLI?

Background:  A perinatal disruption in cerebellar development has been proposed to be a direct cause of autism (ASD; Wang, Kloth, & Badura, 2014). Adults with cerebellar lesions exhibit timing deficits, as indicated by increased timing variability on a finger tapping task (Schlerf, Spencer, Zelaznik, & Ivry, 2007). Much like children with ASD, children with specific language impairment (SLI) show deficits in language and motor development. However, discrete timing is not implicated, because children with SLI do not show deficits in variability during single-effector timing tasks (Zelaznik & Goffman, 2010). Timing tasks that involve coordination of multiple effectors (e.g., clapping) are impaired in SLI (Vuolo, Goffman, & Zelaznik, accepted). Because of the overlap in symptoms, there has been some debate as to whether ASD and SLI are distinct developmental disorders (e.g., Bishop, 2010). We predicted that timing tasks, such as tapping and clapping, might be able to differentiate children with ASD from those with SLI.

Objectives:  The goal of our study was to determine whether children with ASD perform more similarly to an individual with cerebellar dysfunction or SLI on timing tasks with one and two-effectors. If children with ASD show impaired single-effector timing, the results would support the hypothesis of cerebellar dysfunction in children with ASD. If children with ASD do not show impaired single-effector timing, but do show bimanual (multi-effector) coordination difficulties on timing, then the results would indicate that ASD is more similar to SLI.

Methods:  Eleven children with ASD and 6 age-matched children with SLI (to date) participated in a tapping and a clapping task. Hand movements were recorded. Participants were trained to tap and clap to a 600 ms tone presented by a metronome, and to continue tapping and clapping at the same rate for 32 continuation intervals after the metronome disengaged. Six trials were completed for each task. The within-trial, within-participant variability (CV%) of the interval durations was calculated to provide a measure of timing precision. All children also completed the Movement Assessment Battery for Children – Second Edition to index general gross and fine motor skills.

Results: (Preliminary 11 ASD, 4 SLI) The children with ASD (M = 13.29 CV%, SD = 8.57) were more variable than their peers with SLI (M = 10.83 CV%, SD = 3.96) on the single-effector, finger tapping task, but equally variable on the multi-effector clapping task (ASD, M = 15.30 CV%, SD = 6.21; SLI, M = 15.00 CV%, SD = 6.07). The children with ASD also performed more poorly on the standardized test of gross and fine motor skills (M = 4.73, SD = 2.49) than their peers with SLI (M = 8.57, SD = 2.22).

Conclusions:  Unlike children with SLI, children with ASD exhibited a decrement in timing precision on the single-effector timing task. This finding lends support to the cerebellar sensitive period hypothesis of ASD put forth by Wang and colleagues (2014). It also highlights the role of timing tasks, and potentially fine and gross motor tasks, in differentiating children with ASD from those with SLI.