Prior research indicates that individual differences in RSA are an important predictor of aversive emotional responding. One indicator of aversive responding is an exaggerated potentiated startle to threat. While a few studies have shown an association between RSA and abnormal startle potentiation, no study to date has distinguished predictable from unpredictable threat. This is an important distinction given that separable aversive states are elicited by each type of stimulus. Thus, in the present study, we examined whether resting RSA predicts startle response and/or self-reported anxiety during threat of predictable and unpredictable shock in 92 college students. Resting RSA was collected for a total of 6 minutes. Afterwards, participants completed a 10 minute computerized shock task in which predictable and unpredictable electric shocks were delivered. Results indicated that those with lower resting RSA evidenced exaggerated potentiated startle in response to unpredictable, but not the predictable, threat. These findings are in line with a growing body of literature noting that individual differences in resting RSA are an important indicator of anxious responding and extend previous work by highlighting the specificity of the relationship between low RSA and contextual anxiety/unpredictable threat. These results also implicate potential shared underlying mechanisms between low RSA and clinical anxiet
