Retinal Fatigue (Jess Herr)

Jessica Herr

1. Function of the neural layer of the retina

2. Effects of neural fatigue

3. Function of rods and cones

Prior knowledge & experience:

Students are already aware that they can see colors and may also be aware that some people cannot see certain colors.

Students may have experience an after-image effect without clear recognition and understanding of what occurred. However, most students are probably familiar with "seeing spots" after being photographed with a bright flash.

Root question:

What will you see after staring at an image for 30 seconds and then looking at at white page?

Do the after-images appear to have the same colors or different colors than the original?

Target response:

Staring at the image fatigues the photoreceptive cells in your retina so they are temporarily unresponsive to light. As a result, when you look at a white paper or screen after staring at the image, you will see the object in complementary colors. Light reflected from white paper normally stimulates the red, green and blue cones of the retina, but if you have first fatigued the red cones by staring at a red object, these cells temporarily will not respond to red light. As a result, only green and blue cones in the region of the retina are stimulated, causing the image to appear cyan, the complementary color of red.

The image on the right is an example of what students would stare at, and the image on he right is a representation of what would be seen as they stare at a blank screen. The left images shows the complementary colors that would result from retinal fatigue.