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Sheaffer Snorkel. Does it really write more words than do larger pens?


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#41 Hugh

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Posted 15 September 2010 - 02:25 AM

Pholemy? Posted Image

-d





Oh no! not again!! I should wear my glasses when doing thisPosted Image while no spell checker...at least the edit function saves further embarrassmentPosted Image Thanks David

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Hugh
Hugh Cordingley

#42 J Appleseed

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Posted 15 September 2010 - 04:48 PM

Furthermore, though the size of the moon does not change, the angle subtended by the moon at the horizon in the vertical dimension is, in fact, smaller than when it is high in the sky. This is not an illusion.

--Daniel


Technically, I believe that optical illusions are divided into 3 main types:

Physical illusions, which are optical effects caused by the physical properties of light and the interaction of light and objects (eg the way a stick appears to bend when it enters water due to refraction; heat ripples; mirage)

Physiological illusions, which are caused by the physiology of the eye and neural processing of visual information (eg. the blind-spot effect, false-color after images, etc.)

Cognitive illusions, which are caused by the cognitive interpretation of visual information based on learned and assumed experience (eg, pictures that shift between a duck and rabbit depending on how you interpret the picture; distortions caused by false perspective).

The visual angle subtended by the moon at the horizon would fit neatly as a physical illusion. The illusion that the moon appears to be larger at the horizon is a cognitive one.

John

#43 Hugh

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Posted 15 September 2010 - 09:45 PM

It is interesting that the moon illusion is not seen by all people, a stumbling block for most theories. As John has said it's cognitive illusion,and it would appear that not only does the moon look bigger on the horizon but also smaller at the zenith than is really the case. The thinking is that this is "distance-cue" related, which means that the eye focus point changes with a cue such as occurs when looking at the horizon (making object look bigger) where as looking up the cues aren't there so the eye tends to a closer "resting" focus (making objects look smaller).

I'll have to take greater care with the examples i use Posted Image , little did I expect the consequences!!


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Hugh
Hugh Cordingley




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