Superior Auditory Memory in Young Children with ASD? Results From a Non-Word Repetition Task and Relationships with Vocabulary

Background: While vocabulary development is generally delayed in children with autism spectrum disorders (ASD), some do achieve age-appropriate vocabularies.  Additionally, recent studies have reported that individuals with ASD display enhanced performance on auditory processing tasks (e.g., Bonnel et al., 2003) and moreover, demonstrate enhanced learning of the sound structure of novel words (Norbury et al., 2010).  We test the hypothesis that children with ASD have superior auditory memory abilities compared to typically-developing peers (TYP), and that they utilize these abilities to build their early vocabularies.

Objectives: First, we assessed auditory memory using a non-word repetition task, the Syllable Repetition Task (SRT) (Shriberg et al., 2009).  We also examined the type of sound substitution errors made in order to identify the role that auditory encoding skills had in SRT performance, independent of auditory memory abilities.  Substitutions which changed the manner of articulation (e.g., [t] to [m]) were interpreted as a failure to encode auditory information.  Substitutions that preserved the manner of articulation (e.g., [t] to [d]) were interpreted as evidence for partial encoding of the target sound and a functional auditory encoding system (Shriberg et al., 2009).  Second, we examined relationships between auditory memory and receptive language ability.  We answered the following research questions:

1a.  Do participants with ASD perform better than TYP participants on the SRT, specifically on the longest stimuli?

1b.  Do participants with ASD produce fewer manner change errors than TYP participants, reflecting better auditory encoding abilities?

2a.  Is there a correlation between concurrent receptive language and SRT scores?

2b.  Is earlier receptive language predictive of later SRT performance?

Methods: To date, twenty-eight TYP and ten ASD participants between the ages of 2-7 years have been tested.  By April 2012 thirty-one TYP and fifteen ASD participants will be included in the study sample.  Receptive language was assessed at two time points, approximately one year apart, using the Mullen Scales of Early Learning.  The groups did not differ in their receptive language abilities at Time 1.  At Time 2 the SRT was administered.  SRT responses were scored and errors were coded from video.   

Results: Preliminary analyses revealed:

1a.  No significant differences between ASD and TYP groups in overall SRT scores, but a trend for the ASD group to achieve higher scores on the longest stimuli.

1b.  Both groups produced manner change errors approximately half of the time, with no significant difference between groups.

2a.  Significant correlations between concurrent receptive language and SRT scores in both groups.

2b.  Significant correlations between earlier receptive language and SRT scores in both groups.

Conclusions: In the current sample, children with ASD did not demonstrate superior auditory memory ability as assessed by performance on the SRT.  However, the trend observed may prove significant once additional participants are included.  Groups did not differ in their proportion of manner change errors, suggesting similarities in auditory encoding.  Previous receptive language ability was predictive of later SRT scores in both groups, indicating that receptive language knowledge may similarly support auditory memory and, by extension, word learning in ASD.