Open Access

Nico Bast, Tobias Banaschewski, Isabel Dziobek, Daniel Brandeis, Luise Poustka, Christine M. Freitag

• Progression of pupil dilation (PD) in response to visual stimuli may indicate distinct internal processes. No study has been performed on PD progression during a social cognition task. Here, we describe PD progression during the Movie for the Assessment of Social Cognition (MASC) test in n = 23 adolescents with Autism Spectrum Disorder (ASD) and n = 24 age, IQ and sex‐matched neurotypical controls (NTC). The MASC consists of 43 video sequences depicting human social interactions, each followed by a multiple‐choice question concerning characters' mental states. PD progression data were extracted by eye tracking and controlled for fixation behavior. Segmenting PD progression during video sequences by principal component analysis, three sequential PD components were unveiled. In ASD compared with NTC, a distinct PD progression was observed with increased constriction amplitude, increased dilation latency, and increased dilation amplitude that correlated with PD progression components. These components predicted social cognition performance. The first and second PD components correlated positively with MASC behavioral performance in ASD but negatively in NTC. These PD components may be interpreted as indicators of sensory‐perceptual processing and attention function. In ASD, aberrant sensory‐perceptual processing and attention function could contribute to attenuated social cognition performance. This needs to be tested by additional studies combining the respective cognitive tests and the outlined PD progression analysis. Phasic activity of the locus coeruleus–norepinephrine system is discussed as putatively shared underlying mechanism.