At the same time, our results demonstrated an equally important finding, that all participant groups were sensitive to the same discourse context and cognitive constraints. It is well established that mentalizing tasks are difficult for people with autism, even high-functioning individuals (Hale and Tager-Flusberg, 2005
; Tager-Flusberg, 2001b
). It is also frequently claimed that speakers choose referential forms based on judgments about their addressee’s knowledge and focus of attention (Gundel et al., 1993
; Chafe, 1995; Levelt, 1989
). If reference production truly does involve this kind of mentalizing, we might expect individuals with autism to show a significantly different pattern of choosing referential expressions. Why then did we not find greater differences?
There are two possible explanations. One possibility is that our particular participants with autism did not in fact have any difficulty with mentalizing tasks. Since we did not conduct any theory-of-mind assessments, we cannot ignore this possibility. It is known that theory-of-mind abilities vary on a continuum in autistic populations (Tager-Flusberg, 2001b
), and that theory of mind abilities correlate with linguistic abilities (Fisher, Happé, & Dunn, 2005
; Happé, 1993
). However, other studies have found that high-functioning people with autism score lower on mentalizing tasks than control participants, both in childhood and adolescence (Brent et al., 2004
; Kaland et al., 2008
), as well as through adulthood (Kleinman et al., 2001
; Rutherford et al., 2002
). Based on this literature, it seems likely that our participants with autism had at least some degree of difficulty with higher-order mentalizing abilities.
A second possibility is that reference production does not require on-line calculations about the mental state of the addressee, or at least not as much as implied by the literature. This idea is consistent with reports that very young children also tend to use pronouns appropriately (Hickman & Hendricks, 1999), even though they have not fully developed their theory-of-mind abilities at this age (Wellman, 1990
; Wellman & Liu, 2004
). Gundel, Ntelitheos, and Kowalsky (2007)
describe a number of examples of reference from very young children, which attest appropriate usage of a variety of referential forms (pronouns, definite NPs, etc.) by age 3. They propose that this correct usage indicates that “children… are sensitive to the memory and attention state of their interlocutors” (p. 16). While this conclusion seems to be at odds with the tendency for children of this age to fail false-belief tasks, Gundel et al. suggest that the kind of information needed for reasoning about the addressee’s current focus of attention may be different, and easier, than what is needed to pass a false-belief task.
A more extreme version of their proposal, which is consistent with their results and ours, is that reference production does not always, or even typically, require explicit representations of the addressee’s mental state. Even though speakers do monitor for cues to their addressee’s focus of attention, like eye gaze (Clark & Krych, 2004
), the discourse often provides enough information for speakers to produce appropriate expressions without engaging in sophisticated audience design. We therefore speculate that the choice between pronouns/zeros and more explicit expressions involves fewer mentalizing processes than previously suggested (e.g., Bard & Aylett, 2004
; Brennan, 1995
; Gundel et al., 1993
; Levelt, 1989
). Although our participants with autism are likely to have some mentalizing deficit, it is clearly within the limits of what is required for reference production – particularly for the older children, but even for the majority of references by the younger children. This idea can be tested in future research by assessing whether pronoun use correlates with direct measures of theory of mind.
While we can only speculate about the degree to which mentalizing influenced reference production in our participants, our results clearly supported the claim that reference production is modulated by speaker-internal constraints (i.e., the effects of cognitive load). Participants in all groups produced fewer pronouns in utterances that were disfluent (indicating some level of production difficulty), or while under the load of planning a longer utterance. This supports other findings that speakers produce more pronouns when there are fewer characters in the discourse to compete with each other (Arnold & Griffin, 2007
), and when memory resources are not devoted to a secondary task (Griffin & Arnold, 2008
). Likewise, speakers’ prosodic choices are influenced by both communicative goals and speaker-internal processing load (Watson et al., 2008). Thus, while our findings do not preclude the possibility that speakers sometimes choose expressions on the basis of the addressee’s needs, they are also consistent with a growing body of evidence that production choices are often more sensitive to speaker-internal constraints (Arnold, Wasow, Asudeh, & Alrenga, 2004
; Ferreira & Dell, 2000
; Ferriera, 2003
; Ferreira, Slevc, & Rogers, 2005
; Horton & Keysar, 1996
In summary, the results of our study have implications for both questions about how autism impacts language production processes, and the processes involved in reference production more generally. Our study provides arguably the most detailed (to date) discourse analysis of referential choices for individuals with autism. With this approach, we identified the tendency for our younger participants with autism to overspecify references in the conditions where the discourse context was less constraining. This finding demonstrated the importance of utilizing fine-grained linguistic analyses to identify specific areas where the speech of autism is likely to be affected.
The focus of our study was identifying potential processing differences between children with and without autism. But our results also have implications for the understanding of the processes involved in reference production more generally. There was clear support for recent suggestions that cognitive load affects referential choices (Arnold & Griffin, 2007
; Griffin & Arnold, 2008
; Watson, et al., 2008). If we assume that our autism group was representative of the overall population and had some degree of mentalizing deficit, our results also suggest that theory-of-mind problems do not result in a wholesale failure to choose contextually appropriate expressions.
We also established that referential problems for high-functioning children with autism are likely to occur in the direction of overspecification. This runs counter to the prediction that referential failure is most likely to result in uninterpretable references. Instead, it suggests that the differences associated with autism are not really failures at all. Overspecified references may sound clumsy or pedantic, but ultimately result in the listener successfully understanding the message. This is consistent with other descriptions of the pragmatic linguistic choices associated with autism (e.g., Ghaziuddin & Gerstein, 1996
; Wing, 1981
), but is not evidence of insensitivity to the appropriate use of reference. The identification of this processing difference establishes a contrast that may assist in the development of a language phenotype for autism, as well as the development of clinical treatments.