Prosodic Marking of Given, New, and Contrastive Information: Differences Between Children with and without ASD
Objectives: Better characterize the prosodic deficits associated with ASD, focusing on the information-status function of prosody. Identify mechanisms underlying prosodic production in children with and without ASD.
Methods: Children played a computer game with an experimenter. Both viewed a picture of four objects and four shapes per trial on their own computers (e.g., penny, tiger, doorknob, grapes, triangle, circle, square, star). The experimenter asked one of the following questions, and the child answered, e.g. “No, the tiger goes below the grapes.” The target (the tiger) and its movement were indicated by an arrow on the child’s screen.
(1) Given target: Does the tiger go below the triangle?
(2) New target: Does the penny go below the grapes?
(3) Contrastive target: Do the tiger and the doorknob go below the grapes?
Two blind coders rated the acoustic prominence of the target word pronunciation on a six-point scale (1=reduced; 6= prominent/emphatic).
We predicted higher ratings in the New than Given conditions. This is the simplest pragmatic distinction. The Contrastive condition is important because it should elicit prosodic prominence through mechanisms (1) or (3) above. However, it involves the recent mention of the target word, which facilitates pronunciation, and by (2) is predicted to lead to reduction.
Additionally, we tested the child’s sensitivity to the comprehension needs of the listener with a clarification filler half-way through the experiment (“Did you say dog or dock?”) We compared pronunciations before and after this question as a measure of their response to the needs of the addressee.
Results: Preliminary results (18 ASD, 16 typically-developing (TD) participants) reveal that both groups produced similar greater prosodic prominence when the target was New than when it was Given. Both groups also responded similarly to the clarification filler, producing more prominent pronunciations after the clarification than before (for both Given and New targets). However, the groups responded differently to the Contrastive condition: for TD participants, the Contrastive condition was as prominent as the New condition, but for ASD participants, it was less reduced, similar to the Given condition.
Conclusions: The information-status function of prosody was largely preserved in a group of high-functioning children with ASD. However, using prosody to mark contrast was impaired. This reduced prominence for the Contrastive condition in the ASD group may reflect either a lack of pragmatic rule understanding, or a reliance on production facilitation over the addressee’s needs.