Gesture and Speech Production Indicate Audience Hypersensitivity in ASD
Communication and perspective taking are problematic for individuals with autism spectrum disorder (ASD). Although these phenomena have been studied individually in ASD, little research has investigated the intersection between them. When speaking to a face-to-face interlocutor, individuals with ASD produce more pauses than their typically developing (TD) counterparts (Lake, Humphreys, & Cardy, 2011), suggesting that spoken communication is taxing for them. Gesture is particularly informative because it communicates conjointly with speech (Kendon, 1980; McNeill, 2005) and reflects speakers’ sensitivity to listeners’ needs (Alibali, Heath, & Myers, 2001). However, few studies have investigated how individuals with ASD produce it in conjunction with speech. In order to determine whether audience awareness affects verbal and non-verbal communication in ASD, it is necessary to examine how individuals with ASD gesture when communicating with visible and non-visible interlocutors.
In this study, we examined ASD and TD adolescents’ gesture and speech production when speaking to a visible or non-visible interlocutor.
37 adolescents were recruited and tested individually: 16 diagnosed with ASD (age: M=15.53, SD=0.79; FSIQ: M=104, SD=4.25), and 21 TD controls (age: M=16.0, SD=0.50; FSIQ: M=108.6, SD=1.84). Participants viewed a short cartoon video clip and retold what happened in the clip to an experimenter sitting across a table who was either unobstructed or behind an opaque cardboard screen. This process was then repeated with another clip from the same video, and the experimenter in the opposite condition (visible or non-visible). Sessions were discreetly video recorded and were later transcribed and coded using ELAN software (http://www.mpi.nl/tools/). To facilitate comparison with other studies, McNeill’s (2005) gesture coding scheme was used, and gesture production was normalized by speech production.
Overall, participants produced more gesture in the visible than the non-visible condition, and participants with ASD produced less speech and gesture than their TD counterparts. Between-group differences were smaller in the non-visible condition, with participants with ASD producing more speech and gestures when their interlocutor was not visible. ASD and TD participants were similar in iconic and pointing gesture production within the visible and non-visible conditions. However, TD participants produced more metaphorical and emphasis gestures than participants with ASD in both the visible and non-visible conditions. Additionally, across conditions, ASD participants proposed fewer discourse markers (um, uh, etc.) and more pauses in their speech than TD participants.
This work provides evidence that differences in gesture production observed in individuals with ASD are caused by hypersensitivity to the presence of a listener, rather than general speech or motor problems. The results suggest that some of the communication abnormalities associated with ASD may arise from reduced perspective-taking ability. The findings that the gestures of adolescents with ASD were less numerous in the visible condition relative to the non-visible condition suggest that face-to-face interactions are cognitively taxing for individuals with ASD, which negatively affects their communication ability. These data suggest that speech and gesture in high functioning individuals with ASD show relatively mild abnormalities that become greatly exacerbated when they become visibly aware of their listeners.