Page 147 - Demo

Interoception and Facial Emotion Perception1455see Measurements section). This fixed task order was chosen to avoid biases in the lab study which might not have been present in the online study or might influence task responses. More specifically, the heartbeat discrimination task was always the second task to avoid priming participants to listen to their body signals while performing the emotion recognition task. We also did not want participants to be biased in their responses in the heartbeat discrimination task by activating beliefs about general interoceptive abilities via the questionnaires. Therefore, the questionnaires were always completed last. Experimenters were always present in the room during the instruction and practice phases of each task, and left the room for the main task as well as for the questionnaires.The trial structure of the emotion recognition task in the lab study was the same as in the online study: After a central fixation cross lasting 1s, a randomly selected facial expressions video (see Stimuli section) was presented in the centre of the screen for 2s (720 x 480 pixels, average visual angle: 22.12%u00b0 horizontal and 14.85%u00b0 vertical). A 100ms blank screen was then followed by a screen with questions on the emotion label, on confidence in the emotion label decision and on the perceived emotional intensity of the expression (see Procedure section of Study 1). Upon completion of the emotion recognition task, the fEMG electrodes were removed from the participants%u2019 faces, and three electrodes for the electrocardiogram (ECG) were applied to the participants%u2019 upper bodies (see Supplemental Materials). To perform the heartbeat discrimination task (Whitehead et al., 1977), participants were given the instruction to judge whether a set of five tones is played %u201cin sync%u201d or %u201cout of sync%u201d with their own heartbeats via key press. Auditory feedback on R-peaks with a delay of 200ms is typically perceived as synchronously by participants with a high cardiac interoceptive accuracy, and a delay of 500ms is perceived as delayed (Ring & Brener, 2018). The usage of multiple delays can provide a better and more individualized estimate of a participant%u2019s cardiac interoceptive accuracy (method of constant stimuli (Kleckner et al., 2015)). When piloting the task used in the current study, colleagues found that the interoceptive accuracy index resulting from the two interval method was more closely linked to other measures of interoception than the interoceptive accuracy index from the method of constant stimuli, while the two measures were correlated. As it also requires less time to complete, we decided to use the two interval method for the current study. After a 2min baseline heart rate recording, \\ participants judged the synchronicity of five black dots appearing simultaneously (or delayed) with five tones as a