Directing attention toward the body's internal signals (interoception) versus external sounds (exteroception) produces distinct brain activity patterns. Exteroceptive attention flattened overall brain wave power, while interoceptive attention reduced brain signal complexity, increased frontal connectivity and theta oscillations, and modulated the heartbeat-evoked potential (HEP). Classifiers using HEP features correctly identified the attentional state in 17 of 20 healthy participants; power spectral density features classified all 20. In five brain-injured patients, one with unresponsive wakefulness syndrome and one with locked-in syndrome showed willful modulation of the HEP, suggesting they could follow commands. These findings highlight how attention shapes sensory processing and may aid diagnosis in disorders of consciousness.
Mind blanking—a state of apparent mental emptiness—produces distinct brain signatures that separate it from mind wandering and focused attention. In 62 participants performing a sustained attention task, mind blanking was associated with behavioral lapses, reduced fast brain oscillations and complexity over posterior electrodes, and decreased long-range connectivity compared to both mind wandering and on-task states. Event-related potentials showed disrupted visual processing beginning 200 milliseconds after a stimulus, suggesting a breakdown in conscious access to sensory information. Brain activity patterns predicted mental states on individual trials, revealing dynamics that subjective reports alone miss. These findings indicate that being awake does not guarantee consciousness of something; mind blanking reflects genuine gaps in the stream of thought, arising from disruptions in generating or accessing thought content.