Affective Signaling of Children with Autism: Listeners Prefer the Laughs of Children with Autism

Background: Despite a growing body of research on the emotional expressions of children with autism, comparatively little is known about the impact of these expressions on others. Understanding the impact of emotional expressions is vital because many expressions, such as laughter, are critical for developing and maintaining relationships with peers and caregivers. Objectives: The purpose of this study was to investigate the impact of laugh sounds produced by children with and without autism on naïve listeners. Given that qualitative differences have been observed between the laughs of children with autism and those of typically developing (TD) children, we also hypothesized that listeners would be attentive to subtle differences between the laughs, thus allowing them to correctly judge which child produced the laugh. Methods: Participants consisted of 135 college-aged individuals (M age = 19.2, 66% Female). In the first part of the study, participants listened to 40 laugh sounds (half were produced by a child with autism and half by a TD child matched on chronological age). Laughs were randomly selected from a sample of 765 laughs obtained from a prior investigation. Participants rated their affective response after listening to each laugh. In the second half of the study, participants were told that laughs were produced by one of the two groups. Listeners heard 76 laughs and were asked to judge which child produced each laugh. Like the first half of the study, children with autism produced 50% of the laughs, and laughs were randomly selected. Before completing the study, participants were asked to describe the criteria they used to make their judgments and how much experience they had with autism. Results: Results showed that listeners rated the laughs of children with autism more positively than the laughs of TD individuals (p<.001), and that they were above chance levels at judging whether the laughs were produced by children with autism (p<.01). Females preferred the laughs of both children with autism and those of TD children significantly more than males (p<.05). Grounded theory analysis revealed that most participants were listening for acoustic qualities of the laughs such as pitch, volume, or length when making judgments. Despite their accurate judgments, only 19% of participants thought that they could tell the difference between the laughs. No measured variables predicted accuracy. Conclusions: Results from our study suggest that listeners prefer the laughs of children with autism to those of TD children. This preference may be due to subtle acoustic differences in the laughs that mark of the presence of genuine positive affect in children with autism. In contrast with some claims suggesting that children with autism exhibit deficits in their emotional abilities, the current data provide evidence that laughter represents one area where these children are relatively unimpaired. More importantly, our results show that children with autism posses an innate tool that may promote the formation of relationships.