The present study investigated how Chinese children with autism spectrum disorder (ASD) understand mental terms, especially their knowledge of verb factivity. We examined these children's ability to understand mental terms representing true belief (i.e., zhi1dao4, know) and false belief (i.e., yi3wei2, thought) and compared their ability with that of typically developing (TD) children matched with age, and TD children matched with verbal mental age (VMA). Children were asked to participate in a game to find a toy according to the experimenter's testimony, which involved these mental terms. Results showed that all children from these three groups understood zhi1dao4 better than yi3wei2. Particularly, children with ASD performed statistically significantly worse in understanding mental terms than their age-matched TD children, but not differently from VMA-matched TD children. The understanding of mental verbs was correlated with the language ability of children with ASD, and with age, language ability and executive function of TD children. After controlling for the effects of age, general language ability, and executive functions, the group difference of mental verb understanding still existed.
Human languages provide tools for their speakers to communicate mental states. These tools, often referred to as mental terms, provide linguistic labels for the conceptual categories for mental experiences (e.g., Tardif & Wellman, 2000). Mental terms, in many languages, are often used to lead embedded propositions which represent the content of the mental states (de Villiers & Pyers, 2002). Therefore, the meaning of a mental term determines how the subsequent clause is interpreted. The verb factivity of mental terms, defined as the degree of the mental verbs presuppose the veracity of their clauses, and determines the interpretations of the clauses, that is, the likelihood of a belief being true (Cheung et al., 2009, Lee et al., 1999 and Scoville and Gordon, 1980). Strong factive verbs affirm the following clause, and non-factive verbs negate their clauses (Cheung et al., 2009 and Scoville and Gordon, 1980). For example, in the sentence “I know that there is a marble in the box,” know has a high verb factivity, so the clause “there is a marble in the box” is more likely to be true; while in the sentence “I thought that there was a marble in the box”, thought has a low verb factivity, so its clause is less likely to be true. Knowledge about verb factivity, especially the understanding of nonfactive verbs, uniquely correlates with children's understanding of people's false belief ( Cheung et al., 2009, Lee et al., 1999 and Papafragou et al., 2007).
The current study examined how Chinese-speaking children with ASD understand Chinese mental terms, especially the subtle differences in the verb factivity, compared to their age- or VMA-matched TD children. We found that children with ASD showed lower ability in understanding mental terms, compared to the age-matched TD children, even after controlling for the effects of age, general language ability and executive functions. However, both TD children and children with ASD could understand the factive mental verb in the true belief situation, but have difficulty in understanding the non-factive mental verb in the false belief situation.
