Pupil Dilation to Emotional Faces in Relation to Social Anxiety and Autistic Traits in Adolescents with Social Anxiety Disorder
Social anxiety and autistic traits are overlapping but distinguishable symptom dimensions, both in individuals with psychiatric conditions and in the general population. In social anxiety disorder (SAD), autistic traits may predict treatment response. Autistic traits may also be related to individual variation in attentional processes implicated in the development and maintenance of SAD. Both SAD and autism have been associated with atypical autonomic nervous system (ANS) arousal to emotional faces, although the literature is inconsistent. It is not known whether individual differences in autistic traits modulate ANS arousal to emotional faces in SAD. In the present study, we measured phasic pupil dilation, an index of ANS arousal that is modulated by the sympathetic and parasympathetic branches of the ANS.
To examine pupil responses in individuals with SAD as a function of autistic traits, controlling for self-rated level of social anxiety.
Participants were treatment-seeking adolescents with a diagnosis of Social Anxiety Disorder (SAD; N = 23; 3 Male; Mean age = 15 years; SD = 1). Participants viewed images of 10 happy and 10 angry faces presented for 4 seconds while pupil size was recorded at a sample rate of 120 hertz. Stimuli were matched for luminance and low-level visual characteristics. Pupil response was defined as relative change in pupil size from baseline (1 second preceding the stimuli). Samples where the gaze was within the face were included in the analysis. Autistic traits were measured dimensionally with the Social Responsiveness Scale (SRS)1. Social anxiety was measured dimensionally using the Social Phobia and Anxiety Inventory – Child version (SPAI-C)2. We analyzed data using a linear mixed effects model (LME) with random intercepts for individual and trial, and fixed effects for emotion, autistic traits, and social anxiety level.
Significant effects were found for emotion (larger pupil responses to angry vs happy faces; F = 14.66; p = .0002), and autistic traits (higher level of autistic traits predicted smaller pupil responses; F = 7.24 p =.008), but not for social anxiety level, (F = 2.31; p =.12).
Pupil dilation to emotional faces in individuals with SAD may be modulated by autistic traits. Our results suggest that this effect is independent of social anxiety level. This can inform theories about the overlap between autism and social anxiety.
1.Constantino, J. N., & Gruber, C. P. (2012). Social responsiveness scale (SRS). Torrance, CA: Western Psychological Services.
2. Beidel, D. C., Turner, S. M., Hamlin, K., & Morris, T. L. (2000). The Social Phobia and Anxiety Inventory for Children (SPAI-C): external and discriminative validity. Behavior Therapy, 31(1), 75-87.