Materials

Emotionally evocative positive and negative musical examples from Western art music, and positive and negative nonmusical stimuli selected from the International Affective Digital Sound set (IADS) [48] were identified and validated through a separate rating study [49]. More than 400 10-second-duration audio clips from 12 pieces of Western art music were rated for emotional valence (positive-negative) and arousal (high-low) using the circumplex model of affect [50–52]. A final set of 36 musical (18 positive, 18 negative), 24 nonmusical (12 positive, 12 negative), and 9 neutral (pure tone) stimuli were used in this imaging study. These stimuli are fully described in a separate publication [49], and are available from the corresponding author (RL). In the previous rating study, positive and negative stimuli were rated significantly differently on valence. Additionally, musical and nonmusical stimuli were given comparable emotional valence and arousal ratings. Emotionally neutral pure tones were also identified and validated as intermediate between positive and negative stimuli. The three categories did not differ on arousal rating.

Anxiety was assessed with the Beck Anxiety Inventory (BAI) [53]. This twenty-one item questionnaire assesses severity of anxiety symptoms over the previous week. The Affect Intensity Measure (AIM), a brief, 40-item validated self-report tool for measuring strength of positive and negative emotions, was collected to assess affect intensity [54]. Each item is rated on a six-point scale (Never—Almost Always). The AIM returns a total score from all items (Range = 40–240) and three subscale scores: Positive Affectivity (AIMPA; 15 items), Negative Intensity (AIMNI; 6 items), and Negative Reactivity (AIMNR; 6 items) [54, 55]. All participants underwent both SCID administration and BDI-II testing as part of this study. The SCID was used prior to enrolment to determine eligibility. The BDI-II, BAI, and AIM were collected on the day of fMRI testing as a measure of current mood and depressive symptoms, and those ND participants who scored high on the BDI-II were excluded as noted above.