Outline of one experimental session.
GILBERT
The 4-minute relaxation imagery involved the following components (i) closing one´s eyes, breathing deeply and bringing mindful awareness to the breath, (ii) relaxing the body and releasing tension, (iii) multisensory mental imagery of a beach or a forest (this alternated each session), for example, seeing sparkling water, feeling warm sand underfoot, hearing waves and smelling salty air, before settling down on a chair to further absorb the scene, (iv) noticing feelings of relaxation that may arise.The 4-minute self-compassion imagery script involved the following components: (i) informing participants that showing ourselves self-compassion is an effective emotional-regulation tool, and that it does not matter whether or not we believe ourselves to have the characteristics for being compassionate, the important thing is to imagine that we have them; (ii) closing one´s eyes, putting a hand on the heart, breathing deeply and attending mindfully to the breath, (iii) imagining oneself embodying the four characteristics of compassion according to Gilbert [Research assistants were not blinded to task type (as they were present in the room to collect HRV data) or to session number (as only two research assistants collected all data so were aware of how many sessions participants had already attended); however, all data was collected via self-report or physiological measures. The trial was registered retrospectively at clinicaltrials.gov (NCT04647318).