Stimulating Compassion UsingTranscutaneous Vagus Nerve Stimulation

This experimental proof-of-concept study in healthy volunteers investigates whether a specific form of self-relating, namely, self-compassion, can be controlled through non-invasive stimulation of the vagus nerve. The vagus nerve is part of the parasympathetic nervous system (the 'rest and digest' system) and its fibers are spread throughout the upper body, face, and neck, including a branch that innervates parts of the external ear (e.g. the tragus), close to the surface of the skin. This allows the 'auricular branch' of the vagus nerve to be readily stimulated electrically. Importantly, this can be achieved non-invasively using a transcutaneous vagus nerve stimulation (tVNS) device. The investigators will test the effects of tVNS alone and in combination with a meditation-like technique that is intended to increase participants' feelings of self-compassion (self-compassion imagery). In particular, the investigators will assess participants' experience of self-compassion and self-criticism, as well as other outcome measures, before and during stimulation, and again after they perform the self-compassionate imagery exercise. These effects will be compared to three other groups: one that receives tVNS along with a control (sham) imagery procedure, another that receives sham tVNS and self-compassion imagery, and a final group that receives sham tVNS and sham imagery. It is expected that the group that receives active tVNS and the self-compassion imagery exercise will experience the largest average increases in self-compassion and decreases in self-criticism. The findings of this study will help us better understand the role of the vagus nerve in complex cognitive-emotional experiences - like compassion - and may also motivate the development of bioelectronic stimulation methods that can be used alongside psychological techniques for improving self-compassion and reducing self-criticism, particularly among people with certain psychological disorders.