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Journalism / Mass Communication QUESTION #6365
Question 1
The phi phenomenon and persistence of vision are two optical principles that underlie the illusion of motion in cinema. Which of the following BEST distinguishes the two?
  • Persistence of vision creates the illusion of motion between successive frames; phi phenomenon explains why the intervals between frames appear continuous
  • The phi phenomenon explains why a rapid sequence of slightly different still images creates an <em>illusion of movement in the transition</em> between them; persistence of vision explains why the intervals between frames appear to merge because the eye retains one image long enough for the next to take its place✔️
  • Both are identical phenomena described by different scientists
  • Phi phenomenon applies to silent films while persistence of vision applies to sound films only
Correct Answer Explanation

These two phenomena are the optical and perceptual foundations of cinema:

  • Phi Phenomenon: When a series of slightly different still images is shown in rapid succession, the human brain perceives movement in the transition between images, even though no real movement exists. The brain “fills in” the gap.
  • Persistence of Vision: The human eye retains a visual image for a brief fraction of a second after the source is removed. This means the interval between successive film frames appears to the brain as a continuous image rather than a series of individual snapshots.

Together, these two phenomena create the complete illusion of motion in cinema. Motion picture projectors show 24 frames per second, each flashed twice, making the transitions invisible. Eadweard Muybridge's famous 1877 photographic experiment — settling a bet about whether a galloping horse ever had all four feet off the ground — inadvertently demonstrated these principles and laid the foundation for the invention of cinema.