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Can you please tell me why motion pictures look like they're in motion when we view them, when in reality the film is made up of single frames (photographs) that aren't moving at all? And along the same lines, why do we see "flip-books" as action in motion? (I'm looking for a scientific phrase and/or term to help me describe the how and why of the process.)
Question Date: 2003-11-22
Answer 1:

The reason we can enjoy movies and actually see them as moving images instead of just a series of pictures is because we are fooling our brains.

When our eyes detect an image it takes a certain amount of time to send the image to the brain. The brain then processes the images and determines what it is. However, if the images are coming at the brain very fast (between 25 and 60 images per second), the brain does not have enough time to process each individual image so instead it just interprets it as motion (If you are curious, movies are shown at 24 frames per second and TV is broadcast at 30 frames per second).

The concept was discovered in 1834 by William George Horner. Horner invented the first basic motion picture projector, also called a "Zoetrope". A zoetrope is a cylinder with slits along the edge and images painted on the inside. As it spins, the images appear to moving. This link has great instructions on building your own Zoetrope:

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