Look at an optical illusion and you may think you're seeing things --
such as a curved line that's actually straight, or a moving object
that's standing still. You wonder if your eyes are playing tricks on
you.
It's not your eyes. An illusion is proof that you don't always see
what you think you do -- because of the way your brain and your entire
visual system perceive and interpret an image.
Visual illusions occur due to properties of the visual areas of the
brain as they receive and process information. In other words, your
perception of an illusion has more to do with how your brain works --
and less to do with the optics of your eye.
An illusion is "a mismatch between the immediate visual impression
and the actual properties of the object," said Michael Bach, a vision
scientist and professor of neurobiophysics at the University of Freiburg
Eye Hospital in Freiburg, Germany, who studies illusions and has a
large collection of them on a Web site.
Everything that enters the senses needs to be interpreted through the
brain -- and these interpretations occasionally go wrong, Bach told
ABCNews.com. Illusions, he said, may serve as a test bed to determine
whether scientists understand vision correctly.
Susana Martinez-Conde, director of the laboratory of visual
neuroscience at Barrow Neurological Institute in Phoenix, Ariz. offered a
similar definition. "An illusion is a phenomenon in which our
subjective perception doesn't match the physical reality of the world."
Although people popularly call some brain teasers "optical
illusions," this might not be the best term for them, as scientists make
a distinction between optical illusions and what they call visual
illusions.
An optical illusion suggests that the illusion arises because of some properties of the eye, Bach pointed out.
But since optical illusions are rare, a better and more accurate term
is "visual illusions," because this helps to explain why these
perceptions happen.
The Floaters
A good example of an optical illusion - one that actually occurs inside the eye - is floaters.
Floaters are small specks, spots or shadowy shapes that seemingly
float in your field of vision. To some, they look like a bright white
snow or flashes of light.
Floaters are caused by tiny irregularities in the fluid that fills
the eye. In other words, they're real. They become more common as one
gets older.
But nearly every other illusion happens at the brain level, which is
why scientists say they shouldn't be called "optical illusions," and why
the term "visual illusions" is more appropriate.
Instead of thinking that you cannot trust your eyes when you see an
illusion, you really should be saying, "I cannot always trust my visual
system," said Bach. The visual system includes not only the eyes but the
optic nerve, which links the eye to the brain; and the primary visual
cortex, the area of the brain that processes visual information.
Another example of an illusion is when you "see stars" after a hard blow to the head.
According to Bach, seeing stars results from a mechanical stimulation
and activation of the neurons in the eye, which your brain
misinterprets as light. Light does not enter the eye when you hit your
head, but your visual system perceives it that way.
Sunday, September 8, 2013
Sunday, January 18, 2009
THE MOOD DISORDER QUESTIONNAIRE
Please answer each question to the best of your ability.
YES - NO
1. Has there ever been a period of time when you were not your usual self and...
...you felt so good or so hyper that other people thought you were not your normal self or you were so hyper that you got into trouble?
...you were so irritable that you shouted at people or started fights or arguments?
...you felt much more self-confident than usual?
...you got much less sleep than usual and found you didn’t really miss it?
...you were much more talkative or spoke much faster than usual?
...thoughts raced through your head or you couldn’t slow your mind down?
...you were so easily distracted by things around you that you had trouble concentrating or staying on track?
...you had much more energy than usual?
...you were much more active or did many more things than usual?
...you were much more social or outgoing than usual, for example, you telephoned friends in the middle of the night?
...you were much more interested in sex than usual?
...you did things that were unusual for you or that other people might have thought were excessive, foolish, or risky?
...spending money got you or your family into trouble?
2. If you checked YES to more than one of the above, have several of these ever happened during the same period of time?
3. How much of a problem did any of these cause you – like being unable to
work; having family, money or legal troubles; getting into arguments or fights?
Please circle one response only.
No Problem
Minor Problem
Moderate Problem
Serious Problem
4. Have any of your blood relatives (i.e. children, siblings, parents, grandparents,
aunts, uncles) had manic-depressive illness or bipolar disorder?
5. Has a health professional ever told you that you have manic-depressive illness or bipolar disorder?
THE MOOD DISORDER QUESTIONNAIRE
Instructions: Please answer each question to the best of your ability.
© 2000 by The University of Texas Medical Branch. Reprinted with permission. This instrument is designed for screening purposes only and is not to be used as a diagnostic tool.
The MDQ was developed by a team of psychiatrists, researchers and consumer advocates to addressa critical need for timely and accurate diagnosis of bipolar disorder, which can be fatal if left untreated.
The questionnaire takes about five minutes to complete, and can provide important insights into diagnosis and treatment. Clinical trials have indicated that the MDQ has a high rate of accuracy; it is able to identify seven out of ten people who have bipolar disorder and screen out nine out of ten people who do not.
A recent National DMDA survey revealed that nearly 70% of people with bipolar disorder had received at least one misdiagnosis and many had waited more than 10 years from the onset of their symptoms before receiving a correct diagnosis. National DMDA hopes that the MDQ will shorten this delay and help more people to get the treatment they need, when they need it.
The MDQ screens for Bipolar Spectrum Disorder, (which includes Bipolar I, Bipolar II and Bipolar NOS).
If the patient answers:
1. “Yes” to seven or more of the 13 items in question number 1;
AND
2. “Yes” to question number 2;
AND
3. “Moderate” or “Serious” to question number 3;
you have a positive screen. All three of the criteria above should be met. A positive screen should be followed by a comprehensive medical evaluation for Bipolar Spectrum Disorder.
YES - NO
1. Has there ever been a period of time when you were not your usual self and...
...you felt so good or so hyper that other people thought you were not your normal self or you were so hyper that you got into trouble?
...you were so irritable that you shouted at people or started fights or arguments?
...you felt much more self-confident than usual?
...you got much less sleep than usual and found you didn’t really miss it?
...you were much more talkative or spoke much faster than usual?
...thoughts raced through your head or you couldn’t slow your mind down?
...you were so easily distracted by things around you that you had trouble concentrating or staying on track?
...you had much more energy than usual?
...you were much more active or did many more things than usual?
...you were much more social or outgoing than usual, for example, you telephoned friends in the middle of the night?
...you were much more interested in sex than usual?
...you did things that were unusual for you or that other people might have thought were excessive, foolish, or risky?
...spending money got you or your family into trouble?
2. If you checked YES to more than one of the above, have several of these ever happened during the same period of time?
3. How much of a problem did any of these cause you – like being unable to
work; having family, money or legal troubles; getting into arguments or fights?
Please circle one response only.
No Problem
Minor Problem
Moderate Problem
Serious Problem
4. Have any of your blood relatives (i.e. children, siblings, parents, grandparents,
aunts, uncles) had manic-depressive illness or bipolar disorder?
5. Has a health professional ever told you that you have manic-depressive illness or bipolar disorder?
THE MOOD DISORDER QUESTIONNAIRE
Instructions: Please answer each question to the best of your ability.
© 2000 by The University of Texas Medical Branch. Reprinted with permission. This instrument is designed for screening purposes only and is not to be used as a diagnostic tool.
The MDQ was developed by a team of psychiatrists, researchers and consumer advocates to addressa critical need for timely and accurate diagnosis of bipolar disorder, which can be fatal if left untreated.
The questionnaire takes about five minutes to complete, and can provide important insights into diagnosis and treatment. Clinical trials have indicated that the MDQ has a high rate of accuracy; it is able to identify seven out of ten people who have bipolar disorder and screen out nine out of ten people who do not.
A recent National DMDA survey revealed that nearly 70% of people with bipolar disorder had received at least one misdiagnosis and many had waited more than 10 years from the onset of their symptoms before receiving a correct diagnosis. National DMDA hopes that the MDQ will shorten this delay and help more people to get the treatment they need, when they need it.
The MDQ screens for Bipolar Spectrum Disorder, (which includes Bipolar I, Bipolar II and Bipolar NOS).
If the patient answers:
1. “Yes” to seven or more of the 13 items in question number 1;
AND
2. “Yes” to question number 2;
AND
3. “Moderate” or “Serious” to question number 3;
you have a positive screen. All three of the criteria above should be met. A positive screen should be followed by a comprehensive medical evaluation for Bipolar Spectrum Disorder.
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