Pupillary contagion in Williams syndrome

Eye contact is essential in our ability to connect with people. It enhances our understanding of other’s emotions and thoughts and boosts positive feelings around social interaction. When two people lock eyes, their pupils adapt in size to match the pupils of the person they are interacting with. This phenomenon is known as pupillary contagion. It emerges as early as four months old and contributes to building social connections, empathy, and mutual trust during social interactions. 

Williams syndrome (WS) is a genetic condition characterized by high social motivation, emphasized attention to others’ faces, and enjoyment of social interactions. Despite their social drive, individuals with WS often struggle to socialize effectively. They face challenges in understanding people’s emotions and thoughts, forming social bonds, and evaluating the trustworthiness of others.  

The pupillary contagion phenomenon might hold the key to unraveling the underlying reasons for the social difficulties experienced by individuals with WS despite their hyper-social personalities.  

A group of scientists from Swedish and UK universities, led by the first author Johan Lundin Kleberg (Ph.D.), examined pupil contagion in individuals with WS and compared it with that of typically developing infants, children, and adults. The participants were shown images of human eyes with different pupil sizes – constricted, medium, and dilated, while their gaze behavior and pupil size were recorded with Tobii Pro eye trackers.  

Participants with WS did not exhibit pupillary contagion effect, unlike control groups. When a higher pupillary contagion effect was observed in some participants with WS, it correlated with milder symptoms of autism related to social communication, such as gaze dynamics during social interactions.  

The findings of this study propose that the absence of pupillary contagion during social interactions might be one of the key factors contributing to the social challenges faced by individuals with WS. These individuals often struggle with building trust during social interactions, and this ability is intricately linked to pupillary contagion.  

Cited publications

Kleberg, J.L., Hallman, A.E.Z., Galazka, M.A. et al. No transfer of arousal from other’s eyes in Williams syndrome. Sci Rep 13, 18397 (2023)