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Homework Help: Perception of apparent (seeming) motion

  1. Jan 20, 2013 #1
    Hey everyone! I'm having hard times with one assignment and I just can't figure it out. I tried to answer these questions on my own and I sent the finished assignment to the professor. She answered me that I misunderstood the assignment and that I should try to solve it one more time. This assignment is about the Perception of apparent (seeming) motion. The assignment encompasses of two taks. The description of the first one is this:

    Use the public transportation and observe the landscape. Pick a point (a tree or a house) in the landscape and observe which direction is the landscape seemingly moving in front of this point and which direction is the landscape seemingly moving behind this point.

    I wrote that in front of the point it seems faster and behind it seems slower. However, this is incorrect.

    What do you think the answer might be?

    The description of the second task is this:

    During the Christmas some people set some blinking decorations around or on their houses. Some of them, for example look like the colored light is "running" around the house or branches of tree. Explain what caused this and what kind of apparent (seeming) motion this is.

    I correctly answered that the thing what causes this is consequent turning on and off of diodes. Thanks to that our eyes perceive that the light is running. Nonetheless, I couldn't figure out the name of this motion.

    Do you have any idea that the name of that seeming motion might be?

    Thank you for any help! And I am sorry for improper English - some terms here might be inaccurate.

    Have a great day!
  2. jcsd
  3. Jan 20, 2013 #2


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    Staff: Mentor

    "Faster" is not a direction.

    I didn't know that this has a specific name, but that might be language-specific.
  4. Jan 20, 2013 #3
    "Faster" and "slower" are not directions.

    What are the various kinds of apparent motion you learned about? As it's a question that is essentially just matching a description to a definition, there isn't really much in way we can help you without just giving you the answer. Maybe start by listing all the definitions you know.
  5. Jan 20, 2013 #4

    We learned about illusory motion, beta motion and Phi phenomenon. Edit: These terms might be inaccurate brcause I am an international student.
    Last edited: Jan 20, 2013
  6. Jan 20, 2013 #5

    That's true. Well I think that in front of this point the landscape moves back and behind it moves to the front. That's all I can think of.
  7. Jan 20, 2013 #6
    Well after another research, I think that the first task answer is that in front of the point it goes back and behind forward. The answer for the second task is Illusory motion is that right?
  8. Jan 20, 2013 #7
    No, illusory motion is when a static image appears to move. Like this. If you look at the Wikipedia pages for each of the three things you mentioned, there are examples on each page. One of the examples is exactly what you're describing. I think that's about as far as we can reasonably help you for that question, since it really is the exact same example.
  9. Jan 20, 2013 #8
    Edit: it is beta I just saw a picture and that's it. So thank you
    Last edited: Jan 20, 2013
  10. Jan 20, 2013 #9
    Ok, I can't figure out the first task does anyone know? Does the landscape in front of the object move seemingly back and the landscape behind the point forward?
  11. Jan 20, 2013 #10
    Yes. You said this earlier, I thought you had it figured out then? However, the important point is that you specify they are appearing to move relative to the fixed point in the middle.
  12. Jan 20, 2013 #11
    Ok thank You for all help!! I'm just being extremely cautious with this assignment because it is decisive for my grade=)
  13. Jan 20, 2013 #12


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    All of the landscape will appear to be moving backwards relative to the observer in the public transportation vehicle. The landscape in front of the reference point will appear to move backards relative to the refence point (not the observer), and the landscape behind the reference point will appear to move forwards relative to the reference point (not the observer).

    Illusionary motion. There seem to be conflicting definitions for the various terms used for illusionary motion, but best defintions I could find are:

    phi phenomenon - consists of three types of apparent movement: beta, delta, and gamma.

    beta - illusion of motion in a static image where nothing is changing or moving. More of an optical or perceptual illusion.

    delta - pictures displayed quickly in sequence with slight change (delta) in each picture to give the illusion of motion. This would include film, flip books, mutoscopes, zoetropes, ...

    gamma - light emitting devices (gamma) cycled or transitioned in patterns to give the illusion of motion. This would include digital projectors, monitors, led panels, televisions, oscilloscopes, ...

    For the Christmas displays, the blinking lights illusionary motion would be the gamma form of phi phenomenon.
    Last edited: Jan 20, 2013
  14. Jan 20, 2013 #13


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    It is not backwards/to the front. What about left and right? ;)
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