BackgroundWhen receiving mismatching nonverbal and verbal signals, most people tend to base their judgment regarding the current emotional state of others primarily on nonverbal information. However, individuals with high-functioning autism (HFA) have been described as having difficulties interpreting nonverbal signals. Recognizing emotional states correctly is highly important for successful social interaction. Alterations in perception of nonverbal emotional cues presumably contribute to misunderstanding and impairments in social interactions.MethodsTo evaluate autism-specific differences in the relative impact of nonverbal and verbal cues, 18 adults with HFA (14 male and four female subjects, mean age 36.7 years (SD 11.4) and 18 age, gender and IQ-matched typically developed controls [14 m/4 f, mean age 36.4 years (SD 12.2)] rated the emotional state of speakers in video sequences with partly mismatching emotional signals. Standardized linear regression coefficients were calculated as a measure of the reliance on the nonverbal and verbal components of the videos for each participant. Regression coefficients were then compared between groups to test the hypothesis that autistic adults base their social evaluations less strongly on nonverbal information. Further exploratory analyses were performed for differences in valence ratings and response times.ResultsCompared to the typically developed control group, nonverbal cue reliance was reduced in adults with high-functioning autism [t(23.14) = −2.44, p = 0.01 (one-sided)]. Furthermore, the exploratory analyses showed a tendency to avoid extreme answers in the HFA group, observable via less positive as well as less negative valence ratings in response to emotional expressions of increasingly strong valence. In addition, response time was generally longer in HFA compared to the control group [F (1, 33) = 10.65, p = 0.004].ConclusionThese findings suggest reduced impact of nonverbal cues and longer processing times in the analysis of multimodal emotional information, which may be associated with a subjectively lower relevance of this information and/or more processing difficulties for people with HFA. The less extreme answering tendency may indicate a lower sensitivity for nonverbal valence expression in HFA or result from a tendency to avoid incorrect answers when confronted with greater uncertainty in interpreting emotional states.

IntroductionDeficits in emotional perception are common in autistic people, but it remains unclear to which extent these perceptual impairments are linked to specific sensory modalities, specific emotions or multisensory facilitation.MethodsThis study aimed to investigate uni- and bimodal perception of emotional cues as well as multisensory facilitation in autistic (n = 18, mean age: 36.72 years, SD: 11.36) compared to non-autistic (n = 18, mean age: 36.41 years, SD: 12.18) people using auditory, visual and audiovisual stimuli.ResultsLower identification accuracy and longer response time were revealed in high-functioning autistic people. These differences were independent of modality and emotion and showed large effect sizes (Cohen’s d 0.8–1.2). Furthermore, multisensory facilitation of response time was observed in non-autistic people that was absent in autistic people, whereas no differences were found in multisensory facilitation of accuracy between the two groups.DiscussionThese findings suggest that processing of auditory and visual components of audiovisual stimuli is carried out more separately in autistic individuals (with equivalent temporal demands required for processing of the respective unimodal cues), but still with similar relative improvement in accuracy, whereas earlier integrative multimodal merging of stimulus properties seems to occur in non-autistic individuals.