An onlooker looks at a mountain, but the left half of it is gone. It’s not really gone—other folks looking from his location will say that there’s an entire, beautiful mountain there—but the onlooker will insist that he can only see the right half.
This onlooker has Hemispatial Neglect, a disorder characterized by lack of awareness of one side of space. It’s not the same as being blind; someone with Hemispatial Neglect can still have very good vision. It’s not even like you’re closing one eye. In that case, you’ll still be able to see pretty much the same thing as when both your eyes are opened, though the image is slightly shifted.
Put another way: instead of existing inside the world of a film, people with CBS are instead watching a silent production unfolding around them, a production of which they are not actually a part. Indeed, the fact that the hallucinations do not directly interact with the individuals themselves often distinguishes CBS from other disorders like schizophrenia. Patients with CBS are well aware that something isn’t quite right. They are lucid, articulate, intelligent; testing negative for a swath of possible psychiatric and neurological diagnoses.
Indeed, such experiences enabled me to better understand what exactly awareness entails. There exist so many different flavors, each appropriate for a different situation. Knowing what corresponds to a given mental disorder differs significantly from reading a personal blog or watching videos of the interactions between doctors, patients, and their families; and these video and Internet interactions, like talking to someone on Skype versus in real life, are still a far cry from actually being there.