Conscious perception of a stimulus is linked to a specific sequence of brain processes that unfold after about 270 milliseconds, involving superior parietal and superior frontal regions. Using EEG and MEG recordings during a task where participants reported the location and visibility of a brief visual target, multivariate pattern analysis showed that information about stimulus location is still processed in the cortex even when the stimulus is not consciously seen (blindsight). However, only consciously perceived stimuli trigger additional, time-limited neural activity in higher-order brain areas, whereas unconscious processing decays slowly without this chain of activity.
Error detection relies on two distinct brain systems: one tied to conscious awareness and another that operates without it. In people with schizophrenia, the conscious error-detection system is impaired, as shown by a reduced Error-Related Negativity (ERN) in EEG and MEG recordings during a speeded number comparison task. However, on trials where stimuli were presented unconsciously, both schizophrenia patients and healthy controls could still evaluate their own errors above chance levels. This dissociation indicates that non-conscious performance monitoring remains intact in schizophrenia, while conscious metacognition is specifically altered.