Decoding the contents of consciousness from brain activity is one of most challenging frontiers of cognitive neuroscience. The ability to interpret mental content without recourse to behavior is most relevant for understanding patients who may be demonstrably conscious, but entirely unable to speak or move willfully in any way, precluding any systematic investigation of their conscious experience. Until recently, patient studies have used structured instructions to elicit willful modulation of brain activity according to command. Recent work has used a different approach, where the similarity of any given patient's brain activity to that of healthy controls during naturalistic paradigms can help detect high-level cognition and consciousness. This approach is easy to administer, brief, and does not require compliance with arbitrary task instructions. Therefore, it is suited to probing consciousness and revealing residual cognition in highly impaired comatose patients, thus helping to improve diagnosis and prognostication for this vulnerable patient group.