Persistence of Vision Explained: How Movie Cameras Trick Our Brains

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Discussion Overview

The discussion revolves around the concept of persistence of vision and how it relates to the perception of motion in film and video. Participants explore the mechanisms by which movie cameras and projectors create the illusion of smooth motion despite displaying a series of still images at a rapid rate. The conversation touches on both theoretical and psychological aspects of visual perception.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that the brain takes about one-tenth of a second to process a new image, questioning how movie cameras exploit this to create the illusion of motion despite showing 24 images per second.
  • Another participant explains that film projectors display images at approximately 30 frames per second, allowing for a new frame to appear before the previous one has completely faded, contributing to the sensation of smooth motion.
  • It is mentioned that the effectiveness of this illusion may depend on lighting conditions, with darker environments enhancing the persistence effect, while bright light can reveal flicker on monitors.
  • A participant references research suggesting that the persistence of vision theory may not fully explain the phenomenon, proposing that it could be more accurately described as a psychological effect rather than a purely physiological one.
  • Another contribution highlights the complexity of visual perception, suggesting that individual experiences of motion in film may vary significantly due to the brain's processing time and memory, leading to subjective interpretations of reality.

Areas of Agreement / Disagreement

Participants express differing views on the validity of the persistence of vision theory, with some supporting it while others challenge its relevance, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Some claims rely on specific conditions such as lighting and individual differences in perception, which may not be universally applicable. Additionally, the discussion references research that questions established explanations without reaching a consensus on the underlying mechanisms of visual perception.

DeathKnight
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I know it is used to refer to the property of brain/eye that it takes them one-tenth of a second to process a new image after processing one but I just can't figure out how does a movie camera takes advantage of it and fool our brain so that it thinks that its waching a smooth motion though i know that most of them change 24 images a second. I've tried google but coundnt find anything convincing.
Thanks in advance for any help. :smile:
Abdullah
 
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A film projector flashes images at about 30 frames per sec. So each frame is on the screen for a period of time which is less then the persistence of the eye. Before 1 frame has faded a new one is present. Thus you get the feeling of smooth motion.
 
DeathKnight said:
change 24 images a second.
This only works well under dark light, with your pupils dialated and your retina getting just enough over-saturation that the persistance increases.

Under bright light, you can see 60hz flicker on a monitor, but part of this is that the persitance of the monitor is set for faster refresh rates.
 
here is a neat page with a simple explanation and demonstrative animations:
http://www.privatelessons.net/2d/sample/m01_03.html

however, it seems that the persistence of vision 'theory' may not be correct at all according to research done in the 1980s and that it is really a psychological phenomenon. here is a rather interesting (and surprising - to me at any rate) article on that matter:

it has in fact long been determined that the so-called 'persistence of vision' is also probably irrelevant to the effect of (1), a continuous, flickerless image.
PERSISTENCE OF VISION by Stephen Herbert
http://www.grand-illusions.com/percept.htm

it would seem that the commonly propagated explanation of illusion, may itself be an illusion!
 
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Given that the brain takes at least 50mS to process data and somtimes never it's hardly surprising that persistence should be more complex than retina saturation , it is often the case that what you remember is totally different from reallity --- so I guess you can say that everbodies movie is probably different antway.
Ray.
 

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