Using Time Perception to Explore Sensitivity to Emotional Stimuli in Autism Spectrum Disorder

Abstract

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by difficulties in social communication, including challenges in the understanding of emotion. In the temporal bisection task the duration of an emotionally expressive face is overestimated compared to a neutral facial expression (e.g., Droit-Volet et al., 2004). It is hypothesized that this effect is driven by stimulus-induced increases in arousal, which speed the rate of an ‘internal clock’ that meters time. To date, it is not known whether this implicit response to emotional stimuli is present in ASD. We tested 20 adults with an ASD and 26 matched controls. Participants were presented with the classic time bisection task in which they learnt two reference durations, one ‘short’ (400 ms) and one ‘long’ (1600 ms), and had to classify subsequent durations as either more similar to the short or long references. In two conditions, temporal judgements were assessed for face stimuli (angry, happy, fearful, and neutral faces) and a selection of natural images (snarling dog, puppy, spider, and flower) that varied in emotional salience. Like the control group, we found that the group with ASD overestimated the duration of both the emotional faces and the arousing natural images compared to the neutral face and flower. Similar results were found in a parallel study that assessed 85 undergraduate students whose degree of self-reported autistic traits were measured using the Autism Spectrum Quotient questionnaire (Baron-Cohen et al., 2001). Overestimation of the emotional stimuli did not correlate with self-reported autistic traits in this student population. Taken together, the data do not suggest a fundamental insensitivity to the arousing content of either facial or natural images in ASD, or in individuals with a high degree of autistic traits. These findings have implications for understanding how emotional stimuli are processed in ASD and illustrate how timing paradigms can be used to better understand the perceptual experience of clinical populations.