User:Skoch3

2013-05-19T13:28:41Z

Skoch3: Created page with "User page on wikipedia: http://en.wikipedia.org/wiki/User:Skoch3"

User page on wikipedia: http://en.wikipedia.org/wiki/User:Skoch3

1213: Combination Vision Test

2013-05-19T13:27:43Z

Skoch3: /* Explanation */ Adding links to wikipedia articles on specific forms of synaesthesia

{{comic
| number = 1213
| date = May 17, 2013
| title = Combination Vision Test
| image = combination vision test.png
| titletext = If you see two numbers but they're both the same and you have to squint to read them, you have synesthesia, colorblindness, diplopia, and myopia.
}}

==Explanation==

There are two numbers embedded in the big circle of numbers, in a similar way to a common {{w|color perception test}}. But this test can not work for colors because it is just a Black and White picture. Nobody can see it. But at this point the joke is just starting:

The numbers are four and two, forming the number {{w|42 (number)|42}}, which is the famous “{{w|Answer to the Ultimate Question of Life, the Universe, and Everything}}”, according to the book {{w|The Hitchhiker's Guide to the Galaxy}}.

The number 4 is formed by digits 2, 3, 5 and 7, which are the only {{w|Prime number|prime numbers}} in the range 0–9.
The number 2 is formed by digits 3, 5, 7 and 9, apparently all odd numbers in the range 0–9, except for 1.

A normal person does not readily see the big numbers, obviously. However, there is a neurological condition called {{w|synesthesia}}, in which perception in one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. Common examples are experiencing colors when seeing numbers or words ({{w|Grapheme-color synesthesia}}), hearing tones or music while reading words or text, seeing sequences of numbers or month names in a distinct and fixed shape ({{w|Number form}}), etc. If we give some numbers a color, such as how a person with number to color synesthesia would see it, we get this:

[[File:BLIQR6w.png|center]]

The comic playfully suggests that if you have synesthesia as well as {{w|colorblindness}}, then some of the colors might appear identical and so one number would not be visible, only leaving the other number.

The alt-text brings in two more conditions: {{w|diplopia}}, or double vision, and {{w|myopia}}, or near-sightedness. Those who are near-sighted sometimes see distant objects more clearly while squinting. Then they would be able to see the one large number still visible from the synesthesia/colorblindness combination, but because of double vision they see a second copy of it, hence two numbers that are the same.

Since each number would appear in a different color with synesthesia (unlike above where 2,3,5,7,9 are all the same color), the following image better demonstrates how the image might appear to some viewers.

[[File:combination_vision_test_fullcolor.png|center]]

==Transcript==
: Combination Vision Test
: ''a circle filled with several hundred numeric digits''
: If you can see one big number but not the other, you have synesthesia ''and'' colorblindness.

{{comic discussion}}
[[Category:Math]]

explain xkcd - User contributions [en]

User:Skoch3

1213: Combination Vision Test