![]() ![]() ![]() In other cases, perception (which occurs in the brain) can be fooled by what the eye sees accurately. Optical Illusions: In some cases, as with the blind spot experiment, the brain fills in missing information to compensate for the "missing data" coming from the blind spot region, but it can only fill in a regular pattern by sampling the area around the missing data. Compensation: Is a blind person's sense of hearing or smell enhanced, or is a blind person just doing more with the same information than a sighted person does?Į. How has the sensitivity of your retina changed after staring at the dark geometric shape? How long do you continue to see the afterimage?ĭ. Describe what you see in the white circle. Then fixate on the black dot in the middle of the circle to the right. One interesting bit of trivia is that the cephalopod eye (found in the invertebrate molluscs like octopus and squid) evolved independently from the vertebrate eye and, because of a different internal design, lacks a blind spot.Īfterimage test With one eye covered, fixate on the white dot in the center of the "peace symbol" on the left for about 30 seconds. No visual information is sent to the brain from the part of your field of vision projected onto the papilla. There are no light sensitive cells in this area, which is called the blind spot. Within the retina however, there is a small area where the optic nerve connects to the eye this area is called the papilla. The Blind Spot: The retina is like a projection screen on which the image is focused by the lens of your eye. Why can you see but not easily identify colors in dim light? How does this relate to rods and cones? B. Can you make it out more clearly? How does this relate to rods and cones? Try this trick while stargazing and you'll see more!Įxperiment 2: Lay several colored objects in front of you, and very slowly bring up the lights from full darkness. Now look at it using your peripheral vision (from the side). In near darkness, stare directly at an object and attempt to make out the details. ![]() Experiment 1: Sit in the dark for a few minutes to let your eyes adjust. Cones are most densely concentrated in the center of the retina, while rods are more concentrated around the periphery of the retina. Rods are more light sensitive and work better in dim light but are not sensitive to color, so they are important to night vision. Rods and cones: The retina is a thin layer of neural tissue lining the back inside of the eyeball this tissue contains the receptors for vision that are called " rods" and " cones." Cones are color sensitive and work best in bright light. ![]()
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