A visual neglect patient

A classic case of visual neglect, a condition typically associated with damage to the right parietal cortex due to stroke or other injury.

<< opening instrumental music >>

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

She should be able to copy this star easily.

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

[Narrator] But something odd is happening.

One whole side of the star is missing.

Peggy has a condition called
visual neglect.

Although her eyesight is fine,

half of her visual world
no longer seems to matter.

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

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

with creating a three-dimensional representation

of the spatial layout of the world
allowing a person to walk around

to navigate, to avoid bumping into things.

When the right side is damaged

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

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

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

it even determines the spatial look our memories.

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

"Alright, a daisy it shall be"

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

[Peter] It is like a radar system whereby

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

If someone comes into my left hand side now

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

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

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

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

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

that we would normally be aware of.

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

until it's pointed out to her.

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

[Peggy ]"Oh, dear."

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

with the left side missing
same this one and this one

look at this one this is a very good example"

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

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

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

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

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

a problem of consciousness"

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

It is attention really is taking this taken away this

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

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

<< closing instrumental music >>