What is consciousness, and why do cognitive scientists still struggle to study some aspects of it?

What is consciousness? Coming up with an all-encompassing definition is daunting, but we can actually come up with fairly straightforward definitions if we approach consciousness from more specific angles (Koch 2012).

• A common sense definition is that consciousness is the awareness we experience when we are awake and not when we are asleep (or severely inebriated, in a coma, etc.)
• A behavioral definition specifies a checklist of observable actions that qualify as consciousness, for example being able to control movements on verbal command.
• A neuronal definition specifies minimal physiological mechanisms involved in specific conscious sensations.

JR Searle (1998) further identifies consciousness as:

• inner (occurring in the brain and not externally observable),
• qualitative (every conscious state feels a certain way -- experiences called "qualia"),
• and subjective (someone has to experience consciousness).

Chalmers (1995) identifies "easy problems" related to consciousness, which question how information is accessed and deployed and is relatively easy to study; and the "hard problem" of what conscious experiences actually are and how or why they occur.

Jackson (1986) illustrates the hard problem and the difference between processing information and conscious experience with the following thought experiment: consider someone raised in a black-and-white environment, carefully deprived of all exposure to color. Even if the person is educated about the sciences and fully theoretically understands color, they will find actually seeing color for the first time to a novel and unpredictable experience. This experience is what cognitive scientists are still struggling to study.

What is clear, though, is that cognition involves separate conscious and unconscious processes. This is demonstrated by cases of brain damage where patients' conscious and unconscious cognition become dissociated -- blindsight and unilateral spatial neglect are good examples of this, where patients are consciously blind but can still unconsciously navigate spaces, identify objects, and even make decisions based on information that's not consciously available. Ramachandran also presents many examples.