A Burden Shared is a Burden Halved: The Load of Role Sharing on the Brain's Threat Response

Relationships support health and well-being, in part by buffering the effects of stress-related physiological activity (Beckes & Coan, 2011). Load sharing, a process by which two or more individuals distribute (and thus decrease) their effort in responding to environmental demands, is hypothesized to reduce the burden of vigilance for, and response to threats in, the immediate environment (Coan, Beckes, & Allen, 2013; Coan, Schaefer, & Davidson, 2006). This dissertation study investigates the neural threat response in friend dyads (N = 106) facing threats both individually and simultaneously using electroencephalography (EEG). Participants experienced four conditions during threat of shock: while alone, while receiving supportive handholding, while giving supportive handholding, and while facing a threat simultaneously (i.e., joint). By measuring the effects of social support with EEG, we can pinpoint changes in attenuation and threat response to the millisecond thereby better understanding the dynamic interactions of giving and receiving support.

Study 1 tested the effects of social condition on averaged early and late ERPs (i.e., OSN, P300, and LPP) to determine whether experiencing a threat simultaneously with a partner differed from experiencing it alone, when supporting their partner, or when receiving support from their partner. I also investigated the moderation of self-reported perceived social support, relationship quality, and trait empathy. Results indicated that higher perceived support corresponded with decreases in early and later ERPs (i.e., OSN and LPP, respectively) when giving support, higher friendship quality corresponded with decreases in later ERPs (i.e., P300 and LPP) when experiencing threats together, and higher perspective taking corresponded with faster OSN regardless of condition.

Study 2 evaluated how a participant’s neural activity at one time point is predicted by her own neural activity at the prior time point (the stability effect) and by her partner’s neural activity at the prior time point (the influence effect) by using the Stability and Influence Model (SIM), a version of the Actor-Partner Interdependence Model (APIM). Results indicated that 1) neural threat response habituates over time regardless of social condition, and 2) that participant’s neural threat response corresponds with their partner’s threat response at a prior time point. Specifically, partner’s faster and increased neural threat response corresponded with participant’s slower and increased neural threat response, suggesting both overlap and regulation patterns. Results of Study 1 support a load sharing hypothesis when relationship quality is high. Study 2 expands these finding indicating that threat response decreases over time and dyadic interactions suggest overlap and regulation models of processing threat.