International Meeting for Autism Research (London, May 15-17, 2008): Expressive prosody in autism: Effects of prosody function and processing demands

Saturday, May 17, 2008

Champagne Terrace/Bordeaux (Novotel London West)

J. Van Santen , Center for Spoken Language Understanding, OHSU, Beaverton, OR

E. Tucker Prud′hommeaux , Center for Spoken Language Understanding, OHSU, Beaverton, OR

R. Paul , Yale Child Study Center, and Southern Connecticut State University

L. Black , Center for Spoken Language Understanding, OHSU, Beaverton, OR

L. Shriberg , Waisman Institute, University of Wisconsin—Madison

Background:

Expressive prosody is often compromised in autism spectrum disorders (ASD). Less is known about which prosody functions are most affected (e.g., grammatical vs. pragmatic/affective functions) and the role of processing demands.

Objectives:

The purpose of the study was to compare performances of children with ASD vs. typical development (TD) in expressive prosody tasks varying in function (grammatical, pragmatic, affective) and processing demands (repetition vs. pictorial processing).

Methods:

Five experimental tasks were used:

(i) Lexical Stress Task (grammatical+repetition): repeating two-syllable words with initial or final stress.

(ii) Emphatic Stress Task (pragmatic+repetition) (EST): repeating “Bob may go home” with focus on different words.

(iii) Phrasing Task (grammatical+pictorial) (adapted from PEPS-C [Peppé & McCann, 2003]: describing a picture of, e.g., “chocolate, ice cream, and honey” vs. “chocolate-ice cream, and honey”.

(iv) Focus Task (pragmatic+pictorial) (adapted from PEPS-C): correcting focus in a recording describing, e.g., a blue sheep as a black sheep or a blue cow.

(v) Pragmatic Style Task (pragmatic/affective+pictorial): talking about a pictured object using prosody appropriate to address a baby vs. an adult.

The recordings were scored using automated digital methods.

Results:

Children with ASD performed as well as children with TD on any repetition or grammatical prosody task [(i)-(iii)], but worse on those picture processing tasks that required pragmatic or pragmatic/affective prosody [(iv), (v)]. The interaction of Focus vs. EST and ASD vs. TD indicates the importance of input processing demands vs. output demands, which were identical in these two tasks.

Conclusions:

Prosody function and processing demands differentially affect children with ASD. Weakness in prosody is confined to pragmatic/affective functions of prosody. Repeat tasks, regardless of type of prosody, do not tap into these weaknesses, which may be related to echolalia in ASD. This shows the importance of studying prosody generation at deeper levels of processing.

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