The Distributed Nature of Self  Questions to keep in mind: - What causes a sense of self? - Does the left hemisphere ‘interpreter’ bring together a unified sense of self?

The Distributed Nature of the Self What is Self? Consciousness of your own identity (one’s own self) The total, essential, or particular being of each person Narratives that address our past, present, and future

 "Knowledge of the self, the disposition to focus one's ten senses of sight, hearing, taste, touch, smell, feeling, thought, consciousness, memory and experience upon the self, is a part of the process which brings about the cessation of the self." Do you really know yourself??

Is self knowledge its own entity?  fMRI study on brain activation under three conditions where participants made judgments on presented trait adjectives 1. self-descriptive adjectives 2. adjectives describing US President George W. Bush 3. words presented in uppercase font

Is self knowledge its own entity?  Results: * Increased Left Inferior Frontal Cortex Activation for judgments about the self or familiar individuals (George Bush)

Self as a Percept  Ability to recognize one’s own face  Is this seen in the right cerebral hemisphere or left pre-frontal cortex?  Seen in both, so does this contradict the split brain, left interpreter dominance theory?

The Self as an Associative Network  Cowell and Pleydell-Pearce(2000)  idea of self memory system  Knowledge base  Autobiographical knowledge  Abstract  conceptual  processes of access to the knowledge  Studies show left for retrieval in autobiographical memories

The Self as an Associative Network  However,  Markowitsch, 1998  During retrieval, right hemisphere more activated So… “One hemisphere sets retrieval goals while the other reconstructs the resultant episode.”

The Left Hemisphere Interpreter  Left:  Elaborations, associations, logical patterns  Right:  Just what it receives

The Left Hemisphere Interpreter  Metcalfe et al., 1995  When given :   Left and right respond differently….

The Left Hemisphere Interpreter  Metcalfe et al., 1995  When given :   RIGHT

The Left Hemisphere Interpreter  Metcalfe et al., 1995  When given :   Left

The Left Hemisphere Interpreter  Gazzaniga & LeDoux, 1978  Left hemisphere  Right hemisphere

The Left Hemisphere Interpreter  Left hemisphere  Right hand  Right hemispere  Left hand

The Left Hemisphere Interpreter  P.S. “Oh that’s simple. The chicken claw goes with the chicken, and you need a shovel to clean out the chicken shed.” &

The Left Hemisphere Interpreter  Explanation: The left hemisphere doesn’t have information about the snow scene so it explains the response from what it knows. &

The Left Hemisphere Interpreter  B.M. – damage to right parietal cortex  Caused damage to representation of left perceptual field  When asked to point, uses right hand  When asked why?  “because I didn’t want to” use the right.

The Left Hemisphere Interpreter  B.M. – even more….  Further explains that the hand doesn’t even belong to her! Since no input from right, the left makes up their own story. - Doesn’t happen with damage to left.

The Left Hemisphere Interpreter  Capgras’ syndrome  Emotional feeling not matched up with physical appearance.  “interpreter” assumes there is a problem and must be an imposter!  However, why?  How about when talking on the phone?

The Left Hemisphere Interpreter  Left hemisphere focus on elaboration looses reality.  Right hemisphere maintains authenticity  Normal brain compliments itself to “facilitate elaborative information processing”

The Left Hemisphere Interpreter  “The interpreter creates an explanation of reality based upon what it does know, no matter how bizzare.”

* Experiment done by Turk on split-brain patient to assess person-recognition. * Experiment tested hemispheric differences in person- recognition as information The Interpreter and Self-Recognition Test (Assessing person-recognition)

Experiment consisted of a split brain patient (JW) viewing morphed facial photographs * The morphed photos range from 0% to 100% with self images in increments of 10%. * Experiment was done in random order * Images of JW or a familiar doctor were presented 4 times to each cerebral hemisphere for 250ms each The Interpreter and Self-Recognition Test (Assessing person-recognition)

The Interpreter and Self-Recognition Test (Assessing person-recognition) Results * Double dissociation in J.W.’s face-recognition performance * Right hemisphere biased towards recognizing familiar faces not as self * Left hemisphere biased in self recognition

The Interpreter and Self-Recognition Test (Assessing person-recognition) Ensuring dissociation * Other targets used * Same double dissociation, and demonstrated again left hemisphere bias for self recognition and right hemisphere for other faces.

 Both hemispheres by themselves can recognize faces.  BUT cortical networks in the left hemisphere play a more significant role in self recognition.  This shows evidence that self recognition is dissociable from general face processing. This is important to take into account for building a model of social cognition! What does this mean?

If the left hemisphere can recognize self, it might play an important role in the self-memory system (SMS) Even in a disconnected brain, the self appears to be a unified construct and interpreter. When disconnected, the left hemisphere interpreter makes confabulated interpretation. FMRI Studies also show that left parietal areas may be involved in forming egocentric representations. The Left Hemisphere ….Further Thoughts

The article shows that self referential trait processing is unique from other forms of semantic and episodic representation. There also it showed evidence for a left hemisphere interpreter that generates unified sense of self. This was done in the person recognition process of JW - the split brain patient. This shows the importance of the left hemisphere interpreter in self recognition even in a disconnected brain. This interpreter may give rise to consciousness and a unified sense of self. But it is important to understand that while the split brain appears to be dual brains, it is one self! CONCLUSION