Two-Stroke Aparent Motion
source: http://www.lifesci.sussex.ac.uk/home/George_Mather/TwoStrokeFlash.htm
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- StrangE2U
- added this
This is a very cool principle of illusion.
If you were to take two frames that show forward motion, like you see in this image, and play them back, you would end up getting a staggered movement forwards then back, because the first frame is back in distance from where the 2nd frame is. However, if you add a 3rd blank frame, or inter-stimulus interval frame (ISI), the brain does not see the backward movement anymore. (see my 1st response to see the ISI effect)
The dramatic effect of the blank ISI is due to the visual system's temporal response - how it responds to sudden changes in illumination. In bright conditions the response to a sudden change shows an initial positive phase followed by a brief negative phase. The latter can be viewed as creating a negative neural image of whatever preceded the change. So during the brief ISI, a negative neural image of frame-2 is created in the visual system. This negative response combines with the positive response created by frame-1 to evoke apparent motion. The combination of positive and negative images in motion sequences is already known to produce reversed apparent motion, as can be seen in four-stroke motion.
Click the link for another example and also to see what four-stroke motion is.
If you were to take two frames that show forward motion, like you see in this image, and play them back, you would end up getting a staggered movement forwards then back, because the first frame is back in distance from where the 2nd frame is. However, if you add a 3rd blank frame, or inter-stimulus interval frame (ISI), the brain does not see the backward movement anymore. (see my 1st response to see the ISI effect)
The dramatic effect of the blank ISI is due to the visual system's temporal response - how it responds to sudden changes in illumination. In bright conditions the response to a sudden change shows an initial positive phase followed by a brief negative phase. The latter can be viewed as creating a negative neural image of whatever preceded the change. So during the brief ISI, a negative neural image of frame-2 is created in the visual system. This negative response combines with the positive response created by frame-1 to evoke apparent motion. The combination of positive and negative images in motion sequences is already known to produce reversed apparent motion, as can be seen in four-stroke motion.
Click the link for another example and also to see what four-stroke motion is.
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vicafri
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Nice.
- 2 years ago
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vicafri
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CalPerr
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awsome
- 2 years ago
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CalPerr
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Ryan_Edwards
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This will save me keyframes/render times haha!
- 2 years ago
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Ryan_Edwards
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StrangE2U
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Ryan_Edwards:
lol... that was the first thought that went through my head as well! Once you start down the road of after effects, you quickly realize how fast it consumes you... now if only there was a pick whip tool for the real world!
- 2 years ago
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StrangE2U
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StrangE2U
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Here we see the same two frames, but with a 3rd blank grey ISI frame inserted... notice there is no backward movement perceived.
- 2 years ago
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StrangE2U
