Free Will, page-94

Furthermore, according to experiments in neuroscience: the narrator function.

''Experiments on split-brain patients reveal how readily the left brain interpreter can make up stories and beliefs. In one experiment, for example, when the word walk was presented only to the right side of a patients brain, he got up and started walking. When he was asked why he did this, the left brain (where language is stored and where the word walk was not presented) quickly created a reason for the action: I wanted to go get a Coke.
Even more fantastic examples of the left hemisphere at work come from the study of neurological disorders.

In a complication of stroke called anosognosia with hemiplegia, patients cannot recognize that their left arm is theirs because the stroke damaged the right parietal cortex, which manages our bodys integrity, position, and movement. The left-hemisphere interpreter has to reconcile the information it receives from the visual cortexthat the limb is attached to its body but is not movingwith the fact that it is not receiving any input about the damage to that limb.

The left-hemisphere interpreter would recognize that damage to nerves of the limb meant trouble for the brain and that the limb was paralyzed; however, in this case the damage occurred directly to the brain area responsible for signaling a problem in the perception of the limb, and it cannot send any information to the left-hemisphere interpreter.

The interpreter must, then, create a belief to mediate the two known facts I can see the limb isnt moving and I cant tell that it is damaged. When patients with this disorder are asked about their arm and why they cant move it, they will say Its not mine or I just dont feel like moving itreasonable conclusions, given the input that the left-hemisphere interpreter is receiving.

The left-hemisphere interpreter is not only a master of belief creation, but it will stick to its belief system no matter what. Patients with reduplicative paramnesia, because of damage to the brain, believe that there are copies of people or places.

In short, they will remember another time and mix it with the present. As a result, they will create seemingly ridiculous, but masterful, stories to uphold what they know to be true due to the erroneous messages their damaged brain is sending their intact interpreter. One such patient believed the New York hospital where she was being treated was actually her home in Maine. When her doctor asked how this could be her home if there were elevators in the hallway, she said, Doctor, do you know how much it cost me to have those put in?

The interpreter will go to great lengths to make sure the inputs it receives are woven together to make senseeven when it must make great leaps to do so. Of course, these do not appear asgreat leaps to the patient, but rather as clear evidence from the world around him or her.''   Michael Gazzaniga