Use of Evidentials in Turkish-Speaking Children with High Functioning Autism

Background: Turkish is an agglutinative language, with a rich and regular morpho-syntactic system. One of the structures of this system, the indirect evidential –mis, requires both syntactic and pragmatic knowledge to be used properly. Syntactically, –mis is produced after the verb but negation and/or tense/aspect markers can intervene (compare Ali gelmis = ‘Ali come + evidential marker' = Ali came, apparently with acmayacakmis = ‘(He) + open + negation + future + evidential marker' = He will not open, evidently). As a full syllable, -mis is a perceptually salient morpheme. Pragmatically, –mis conveys indirect past experience, which is based on inference or hearsay, and encodes information which happens outside conscious awareness. Thus, the indirect evidential –mis presupposes presence of theory of mind skills, which are necessary to attribute mental states to oneself and to others. The interplay between the pragmatic and morpho-syntactic systems in Turkish makes -mis an interesting structure to study with individuals with high functioning autism, because these individuals have mostly intact grammatical skills coupled with impaired social-pragmatic skills. Objectives: Investigate the use of the indirect evidential –mis in Turkish high functioning children with autism, as a salient grammatical structure that taps into theory of mind abilities. Methods: We tested five children with high functioning autism (mean age = 9.4 years, SD = 3.78). Our control group consisted of four children with Down syndrome (mean age = 11.5, years SD = 2.38), and five typically developing children (mean age = 6.3 years, SD = 2.33). Children were administered a wordless picture book: “Frog, where are you?”, and were told to tell the story that they saw in the pictures. Children's performance was videotaped, and the number of times children used the indirect evidential –mis, as well as their total mean length of utterance in morphemes (MLU), were calculated from the videotapes. Results: Children in all three groups did not differ from each other in their MLUs (M(ASD) = 4.18, M(DS) = 4.20, M(TYP) = 4.23). In contrast, children in all three groups significantly differed from each other in their use of the indirect evidential -mis, χ2 (2) = 7.66, p < .05. Children with autism produced significantly fewer utterances with –mis (M = 1.5) than both the typically developing children (M = 27.4) Mann-Whitney U = 1.00, p < .05, and the children with Down syndrome (M = 27.0), Mann-Whitney U = 1.50, p < .05. No significant differences were found between the typical and the Down syndrome groups. Conclusions: High-functioning children with autism have difficulty with the indirect evidential –mis, demonstrating how pragmatic skills in Turkish influence aspects of morpho-syntactic development.