There are many theories put forth to explain human consciousness and experiments are running to test them. With all the discussion around AGI, it’s timely to keep an eye on them.
Higer-order theory
Humans become conscious of a thing (like what they are seeing) when there is a meta representation of it in the higher-order parts of the brain. This is kind of like the “symballs” analogy from I Am a Strange Loop.
Global workspace theory
Information enters consciousness when it is accessed and broadcast in a “workspace”, moving information from local processing units to the brain-wide workspace.
Integrated information theory
Concsciousness arises from the integration of information in a system where the greater degree of integration (more connections) the higher the level of consciousness.
See also: Consciousness is categories but as Douglas Hofstadter would argue, it is conscious or it is not, there is no unit of consciousness
Recurrent processing theory
There needs to be a loop of information flow from higher-order cognitive areas to lower sensory processing areas in both directions—top-down and bottom-up.
See also: Presence of a feedback loop shifts perception from mechanics to desires