The DFA task (see Coan et al., 2001 and Levenson, Ekman, and Friesen, 1990) was performed by participants in between the first and second blocks of resting EEG recording on each day of EEG assessment. Facial movements described below are numbered according to the Facial Action Coding System (FACS; Ekman & Friesen, 1978). Individual facial movements are referred to as action units (AU) in FACS. Four facial expressions were performed, representing the following emotions: anger (AUs 4 + 5 + 7 + 23/24), fear (AUs 1 + 2 + 4 + 5 + 15 + 20), happiness (AUs 6 + 12 + 25), and sadness (AUs 1 + 6 + 15 + 17). Facial expressions were each held for 1 minute, during which time EEG was recorded. The experimenter communicated with participants via microphone regarding how to make each facial movement, and participants’ faces were closely observed via video monitor to ensure that each facial movement was performed correctly. Participants had no visual feedback, and auditory feedback consisted of describing the intended facial movement again (e.g., “raise your upper eyelid”).
