Passive conditions
During Passive Exteroception, participants were asked to visually monitor a circle as it expanded and contracted periodically on the MRI-compatible visual display without making any behavioral responses. The circle’s pulse frequency was set to match participants’ in-scanner breathing frequency, obtained from a respiration belt worn by participants in the scanner (usually ∼12 Hz). During Passive Interoception, participants viewed a stationary circle on the screen while attending to sensations of the breath.