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<< opening instrumental music >>

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[Narrator] Unlike Graham,[br]Peggy Palmer has normal vision.

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She should be able to copy this star easily.

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[Peggy] "I'll never get this star[br]I'm hopeless at this."

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[Narrator] But something odd is happening.

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One whole side of the star is missing.

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Peggy has a condition called [br]visual neglect.

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Although her eyesight is fine, [br]

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half of her visual world[br]no longer seems to matter.

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Ten years ago, Peggy suffered a stroke[br]in the parietal lobes of her brain.

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[V.S. Ramachandran][br]"The parietal lobes are concerned mainly

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with creating a three-dimensional representation

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of the spatial layout of the world [br]allowing a person to walk around

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to navigate, to avoid bumping into things.

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When the right side is damaged

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the patient is unable to[br]deal with the left side of the world.

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[Narrator] This condition has fascinated[br]neurologists for more than a century

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because it reveals not only how the[br]brain shapes the way we perceive space in the present

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it even determines the spatial look our memories.

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This became apparent when Peggy was asked[br]to draw a daisy from memory.

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"Alright, a daisy it shall be"

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[Narrator] For neuropsychologist Peter Halligan[br]Peggy's drawings reveal exactly what's gone wrong.

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[Peter] It is like a radar system whereby

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the actual radar system on the left hand[br]side is no longer working well.

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If someone comes into my left hand side now

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or I hear a sound my eyes will immediately[br]move to left hand side

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that makes me, for evolutionary [br]purposes very aware of my environment

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because I wasn't aware of those things I[br]would have accidents

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I'd get hurt or I might get eaten by wild[br]animals and whatever.

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Now, in Peggy's case she will not attend[br]to those things

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that we would normally be aware of.

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[Narrator] Peggy thinks she's drawn her daisies right

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until it's pointed out to her.

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[Peter] "You've noticed that, have you?"

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[Peggy ]"Oh, dear."

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[Peter][br]"So what Peggy's drawn for us is several nice daisies

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with the left side missing [br]same this one and this one

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look at this one this is a very good example"

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[Peggy] "I've done it on all of them"

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[V.S. Ramachandran] Which means she's not only[br]neglecting events in the world but when she

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conjures up a mental image she's ignoring[br]the left side of that mental image.

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[Peggy][br]"I thought I was going all the way around you see"

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[MD] "And the shows you that this is not[br]simply a sensory problem but

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a problem of consciousness"

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[Peggy] "It's cause I was so concentrated on[br]that side takes everything away, you see

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It is attention really is taking this taken away this

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there must be two attentions somewhere in your[br]body one side's taking another one away.

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I can't make it out at all, very odd"

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<< closing instrumental music >>