"Brain research has shown that systems occupying the posterior convexity of the cerebral hemisphere are innvolved in organizing
Brentano's duality. When the parietal lobe systems are injured, the patient may no longer feel the arm on th e side opposite the brain injury to be his own. One of my students who sufferred such an injury dubbed her arm "Alice" and stated "Alice doesn't live here any more". Despite the loss of belongingness, the arm routinely performs many tasks , such as bringing a cup of coffee to the person's mouth, much to the surprise of the person when she realizes what has happened. Damage further back in the convexity produces "blind sight". Here again the person can perform many rountine tasks that demand an optical input from the blind side, but the patient is unaware of, is blind to, the input. With an intact brain , we are aware of ourselves as "seers" and of what is being seen.
In these and similar instances, awareness of one's bodily self and the environment is impaired. "Alice" isn't any longer part of me; this blind-sighted optically guided behavious isn't "mine". From such observations one can infer that ordinarily these brain systems operate to allow awareness of a corporeal "me" to occur. When impairment takes place, the distinction in awareness between perceiver and perceived no longer exists - much as a colourblind person cannot differentiate between red and green. In the absence of difference between perceiver and perceived (hand and cup; eye and colour) neither of them exists.
My main idea is to show where the different viewpoints come from, and then to have not only just an ontological monism, but also an epistemological pluralism. And the ontological monism comes essentially from one's experience"