Give Me a Sine: Can Sinusoidal Patterns of Nonverbal Synchrony Differentiate between Individuals with Social Anxiety Disorder and Panic Disorder?

• We examined nonverbal synchrony during diagnostic sessions of individuals with SAD and PD. • We used Motion Energy Analysis to objectively derive nonverbal synchrony from videos. • Temporal changes in nonverbal synchrony were best modelled by a sinusoidal wave. • Individuals with SAD had greater sine wave amplitudes compared to individuals with PD. • Implications for psychopathology and diagnosis of SAD are discussed. Individuals with social anxiety disorder (SAD) have been found to have distinct patterns of nonverbal synchrony with others. In the present study, we examined whether patterns of nonverbal synchrony differ between individuals with SAD and individuals with panic disorder (PD). We examined diagnostic interviews of 29 individuals with SAD and 22 individuals with PD, and assessed nonverbal synchrony using motion energy analysis (MEA). We divided interviews into 10 segments and derived nonverbal synchrony indices for each segment to capture changes in nonverbal synchrony over the course of the interview. According to our first hypothesis, we found that nonverbal synchrony was best modelled by a sinusoidal model ( r 2 = .59) which explained significantly more variance than linear, quadratic and logarithmic models. This suggests that nonverbal synchrony is best characterized by a repeating pattern of increases and decreases. According to our second hypothesis, we found that sine wave amplitudes were greater among individuals with SAD compared to those with PD. Thus, individuals with SAD experienced greater fluctuations in nonverbal synchrony during the interview, compared to individuals with PD. We discuss these findings in the context of models of SAD and models of synchrony, as well as suggest implications for research and clinical practice.