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Informal Experiment:

  1. I look up at a wooden beam on the ceiling, or I look at the office door; both the door and the ceiling are about 2 meters from my face.
  2. I rotate my face 90 degrees left or right at a rate of about 90 degrees per second. (You may have to adjust this rate to experience the flicker. Too fast or too slow, and you won't experience the flicker.)

Results:

  • My visual perception (of the edge of the door or ceiling) flickers rather than being smooth and continuous.
  • I typically perceive 4 (but sometimes 5 or 6) images during the rotation, which translates to 1/3 second between images or one image per 30 degrees of rotation.

Notes:

  • Ensure that ambient illumination doesn't flicker. Sunlight is suitable. Most electrical light that runs on AC is not.
  • I understand that not everyone who tries this experiment will experience this phenomenon.
  • This phenomenon also occurs when viewing a sheet of paper held at arm's length and pressed against a contrasting wall (e.g., white paper on brown wall). Rotating the paper instead of your face does not generate the phenomenon.
  • The intention of the linked YouTube video is only to show which plane to rotate.
  • I recorded a video of my face during the experiment. Reviewing the video, I see no eye movement.

Question:

Is there any research on this phenomenon? (I have been unable to find anything on it, perhaps because I don't know the proper terminology.)

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  • $\begingroup$ I would suspect lag or "stuttering" in eyeball rotation to be a dominant factor in this phenomenon before looking to less externally measurable components. $\endgroup$
    – msw
    May 19, 2012 at 16:14
  • $\begingroup$ See cogsci.stackexchange.com/questions/8716/… $\endgroup$
    – John Pick
    Dec 4, 2014 at 2:00

1 Answer 1

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I'm guessing that you are experiencing the interplay of two mechanisms: When you start to turn your head, the "vestibulo-ocular reflex" tries to hold the visual scene steady by counteracting your head movement. But as you continue to turn your head (apparently at about 30 deg. intervals), a "saccade" kicks in to restore your gaze to a point straight in front of your face.

A similar effect can be observed when the visual scene moves, as when you look out a train window, but in this case, rather than the vestibulo-ocular reflex, it would be "smooth pursuit eye movement" that tries to hold the visual scene steady. (Wikipedia has good articles for all three of the quoted terms.)

An interesting way to check this hypothesis would be to videotape your face as you perform the experiment and observe your eye movements in the video. I'm looking forward to a YouTube posting...

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  • $\begingroup$ I took your suggestion. I recorded myself and reviewed the video: my eyes were stable -- no saccades and no vestibulo-ocular reflex. I wouldn't have expected the vestibulo-ocular reflex because eye muscles can't rotate the eyes about their pupils, right? I wonder if the phenomenon I experience is saccadic masking without any eye movement. $\endgroup$
    – John Pick
    May 21, 2012 at 2:25
  • $\begingroup$ Oh, I misunderstood what you meant by rotating your head: I thought it was rotation around the vertical (superior-inferior) axis, but you are talking about the anterior-posterior axis. - Perhaps this is related to Wagon-wheel effect with continuous illumination - although you did state that the effect doesn't happen when rotating the image, only when rotating your head. $\endgroup$
    – Peter Helfer
    May 21, 2012 at 14:26

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