

Schizophrenic Brains Not Fooled by Optical Illusion - lockem
http://www.wired.com/wiredscience/2009/04/schizoillusion/


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dean
I love the irony that sufferers of a disease "characterized by hallucinations,
delusions", see the actual visual information while healthy viewers are
utterly unable to see it.

And this: "Schizophrenia patients, meanwhile, may be unable to modulate this
pathway, accepting the concave face as reality." is just too ironic,
considering that the concave face _is_ reality.

Maybe Schizophrenics are not the delusional ones.

~~~
wtallis
The way I think about it: our brains create perception by combining raw
observations with expectations derived from a mental model built on
experience, in a process similar to a Kalman filter. Most of the time, the
correction based on the mental model helps, such as when an object is
partially obscured. Cases like the concave face are false positives for normal
people, where experience overrides percpetion. Schizophrenics weight the
observations more heavily than the predictions, so they are less likely to
experience false positives, but I would expect them to be consequently more
likely to experience false negatives (ie. perceiving things too literally, in
spite of logic).

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defdac
"Schizophrenics aren’t the only ones who see the concave face — people who are
drunk or high can also ‘beat’ the illusion."

I had a three beers watching the video, and the first revolution was a concave
face. When the next revolution came I saw the illusion and now the illusion is
so powerful I can't see it as concave face anymore. I hope that rules me out
as schizofrenic...

~~~
defdac
Wait. Who wrote this.

~~~
samdk
Contrary to popular belief, schizophrenia is _not_ the same thing as
dissociative identity disorder/multiple personality disorder. (Which is I
believe what you were suggesting with that joke.)

From Wikipedia:

    
    
        Schizophrenia is a mental disorder characterized by a disintegration of the 
        process of thinking and of emotional responsiveness. It most commonly
        manifests as auditory hallucinations, paranoid or bizarre delusions,
        or disorganized speech and thinking, and it is accompanied by significant
        social or occupational dysfunction.
    

<http://en.wikipedia.org/wiki/Schizophrenia>
<http://en.wikipedia.org/wiki/Multiple_Personality_Disorder>

~~~
theblackbox
"dissociative identity disorder/multiple personality disorder" has been all
but dropped by mainstream psychology. It's considered to be an artifact
explained as being induced by a number of factors including attention seeking,
desire to please therapist, extreme hypochondria and mimicry.

~~~
wilzy
Whether or not it has been dropped by mainstream (source?) - you paint
dissociative identity disorder in such a poor light - choosing only to focus
on characteristics that make it controversial. I think you'll find that in
fact there is simply a lack of consensis amongst psychologists for its basis -
which happens to be the case for many 'disorders' in this arena.

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sp4rki
I actually saw a concave face until I read the article. Now I see a regular
face. I'm not drunk, high, or otherwise on any substance. I hope I'm not
schizophrenic, though for some reason I've always thought that it would be
awesome to have it like for a few days. So yeah. Concave faces.

~~~
wilzy
Given the absence of a highly detailed model, in this case a Charlie Chaplain
mask, the illusory effects may be due to the absence of sufficient visual
depth cues - similar to the effects seen in the "Spinning Dancer" effect. As a
further example, next time you see a plane in the air making a turn at a great
distance from you, there are actually two ways you could perceive its
direction - all dependant on what you convince your brain it to be first. I
would not draw too many conclusions from such a vague study.

~~~
sp4rki
I agree. It's all dependent on what your brain sees first. It so happens that
the absence of visual detail makes it easier to decide the mask as seen from
the front instead of from the back. The moment your brain is told that it
should not be seeing the concave face a switch turns on telling you how to
'see' the mask.

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DevX101
Am I the only one who has to always look up the definition (w/ example image)
for concave and convex to differentiate them?

~~~
runningdogx
It's probably one of those things people end up memorizing, when learning
about lenses or 3d figures like polyhedrons. It's like latitude and longitude.
You can try to derive meaning from e.g. "lat = lateral", but then, do the
lines go across or are they measuring distance across (which would make the
lines vertical)? Either you memorize the correct answer, or you can easily get
mixed up by over-analyzing the meaning.

concave -> (cave, cavity) -> hole

convex, you sort of just have to memorize. As best I can tell from
introspection, I've associated the sound/visual of "vex" with "outward"

~~~
rdrimmie
I've been doing a lot of geo-related work lately and confounding latitude and
longitude was a regular source of logic errors. Only useful for North America,
but my mnemonic for lat/lng is "latitude has a positive attitude". It doesn't
necessarily help when identifying which is which on a map, but when using them
for calculating proximity or drawing polygons on a map it works every time.

~~~
RiderOfGiraffes
The lines of longitude are always long, whereas the parallels of latitude can
be shorter, and are always "parallel" (in some sense).

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klocksib
Newscientist also covered this. They have a couple more masks to look at
[http://www.newscientist.com/article/dn16911-schizophrenics-s...](http://www.newscientist.com/article/dn16911-schizophrenics-
see-through-hollowmask-illusion.html)

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Trindaz
Maybe the fact that I'm the only one mentioning this means I'm a little less
intelligent than the rest of us, but...

Isn't a 'real' illusion one that causes you to see something that _isn't_
objectively there? For example, The Grid illusion
(<http://en.wikipedia.org/wiki/Grid_illusion>).

If you find an alternative way to create an _identical_ image, then it's
forgery, not an illusion.

Put another way, the Grid Illusion is to "worng sleplnig" what the Hollow Mask
is to "conversation" (a word in both the English and French languages)

~~~
davidmathers
Did you watch the video?

~~~
Trindaz
Yes. Continuing the word based analogy, the video is just permutations of
"conversation" leading up to it's correct spelling, then more permutations.

If you take the frame that show's the inside of the mask alone, is there a way
to prove the image is of a concave object? To see it as convex is arguably
'wrong' but it's a moot point because you're looking at something that is
objectively identical to a convex object anyway.

Couldn't I just extend your argument to say the fact that you see a face at
the very start of the movie is an illusion? After all it's a _mask_ , not an
actual face.

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ookblah
err, i was able to switch it back and forth at will. however, my mind
definitely kept wanting to visualize the concave face.

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pyre
I remember reading and article/post/whatever a while back that said that some
natives/tribes somewhere didn't see optical illusions. The implication was
that it might be a product of more industrialized living.

( I may be confusing this a bit here. The first part may have been an article,
and the second part may have been part of an HN discussion on it. )

~~~
apl
There are _certain_ (secluded) populations that do not report _certain_
illusions (e.g., Muller-Lyer effect) as strongly as Western subjects do.
Standard explanation is that, living in architecturally under-developed
environments, they lack experience with corners, thereby diminishing corner-
related illusions.

But that's not immunity, it's merely a highly interesting artifact. Goes to
show that psychology's biggest problem might be excessive reliance on college
students as test subjects.

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m0nastic
I'll have to show this to my girlfriend later. She's been diagnosed as
Schizophrenic, but has never agreed with that diagnosis.

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klbarry
I could only see it sticking out and couldn't change it back at all. My
girlfriend, who's much more much more of an empath and more artistic, could
switch it back and forth. Interesting...

