consciousness

Consciousness is the state of being aware of and able to think about oneself and the surrounding environment. It encompasses qualitative experiences (phenomenal consciousness) and the ability to access information for reasoning and reporting (access consciousness). It also includes varying levels of wakefulness and arousal.

Historically, consciousness has been a central concern of philosophy and, since the 19th century, of cognitive science and neuroscience. Debates have focused on whether consciousness can be reduced to physical processes or requires something extra, and on how subjective experience relates to objective description.

Major theories include physicalist accounts, which seek to explain consciousness in terms of brain processes; dualist or non-physicalist views; and specific proposals such as global workspace theory (conscious experience as widespread broadcasting of information in the brain) and integrated information theory (consciousness as integrated information with a certain structure). Other approaches include higher-order thought theories and predictive processing or embodied cognition.

Neuroscientific research identifies neural correlates of consciousness, typically involving widespread cortical networks and coordinated activity with the thalamus. No single brain region suffices; conscious states are associated with patterns of activity and communication across regions. Methodologies include neuroimaging, electrophysiology, and pharmacological manipulations that alter consciousness (sleep, anesthesia, coma).

Consciousness comprises awake states, sleep and dreaming, and altered states. Philosophical problems include the hard problem of why and how subjective experience arises from physical processes, and the 'easy' problems of listing functions. The study informs ethics and AI debates about machine consciousness and the status of non-human animals and patients with impaired consciousness.