======Blind Spot======


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**Alternative titles:** Locating the Blind Spot, Finding the Optic Nerve Gap
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====Summary====                   
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====Procedure====  
  - Give each student a 3 x 5 inch card (or other stiff paper) and a black marker.
  - Instruct students to draw a dot on the left side of the card and an X on the right side.
  - Hold the card at arm’s length, with the X on the right.
  - Close the right eye and look at the X with the left eye while staying aware of the dot.
  - Slowly move the card closer to the face until the dot disappears, then reappears.
  - Repeat by closing the left eye, looking at the dot with the right eye, and noticing when the X disappears.
  - Draw a straight line connecting the dot and the X with a ruler.
  - Repeat the activity; this time the brain fills in the missing part of the line, creating the illusion of a continuous line.



====Links==== 
Quick Blind Spot Test - Vision Vibes: 
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📄 Blind Spot- American Academy of Ophthalmology: [[https://www.aao.org/museum-eye-openers/experiment-blind-spot]]\\


====Variations====
  * Try using different shapes or colors instead of a dot and an X to see if the blind spot effect changes.
  * Test at different distances to compare how far away the card can be while still making the dot or X disappear.
  * Use both eyes open to observe how one eye compensates for the other’s blind spot.



====Safety Precautions====
  * Do not press objects into the eyes while performing the activity.
  * Avoid straining vision by taking breaks if eyes become tired.
  * Ensure students do not draw markers too close to their faces when testing.




====Questions to Consider====
  * Why does the dot or X disappear at certain points? (Because the image falls on the optic nerve, where there are no light-sensitive cells.)
  * Why don’t we normally notice our blind spot? (The brain fills in the gap, and the other eye compensates when both eyes are open.)
  * What happens when a line is drawn between the dot and X? (The brain fills in the missing section, creating the illusion of a continuous line.)
  * What does this activity reveal about how the brain processes vision? (It shows that vision is not just input from the eyes but also interpretation by the brain.)