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Walking, Balance, depth perception and pattern recognition

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    Walking, Balance, depth perception and pattern recognition

    So I do fireplace service and a lot of the work is on new construction which these days means lots of stone.

    The other day we had a job where the steps and the driveway were made out of the same stone pattern. I stumbled and nearly fell 3 different times because I couldn't tell where the steps started and stopped. It is not something I ever noticed before but I remember reading once how cats judge distance by the pattern of the surface and that is kind of what it was like to me. Going down was worse than up since I was looking down on a uniform pattern going up there was a break at each step rise so it was easier.

    I also know that our depth perception is a result of both eyes working together and since I have had frequent bouts of ON one of my eyes is not as strong as the other so I am wondering if my depth perception may have been off for years and I never noticed due to pattern recognition.

    Just wondering anyone else notice anything like this, or now that I brought it up can you look at some of your times where you had balance issues and think if it might have been caused by similar patterns throwing your depth perception off?
    Rise up this mornin, Smiled with the risin sun, Three little birds Pitch by my doorstep Singin sweet songs Of melodies pure and true, Sayin, (this is my message to you-ou-ou

    #2
    Taowarrior

    Yuck! That is very disconcerting and troubling! And dangerous for you! Although I have not had any ON episodes in my MS journey, I have had issues with depth perception. Fortunately, it only happened a couple of times before I got new glasses.

    The first was when my DH was landing a Cessna. It seemed to me we weren't close enough to the runway when he pulled back to flare. Before I could say anything we landed. If I had been in the left seat, I would have made a pretty hard landing and probably damaged the landing gear! I don't have any problems in the air, just on the tarmac.

    The second time I remember was when I went to Cleveland Clinic for a complete neuro exam and testing. I almost fell flat on my face, because the carpet in the large waiting room had such a wild pattern my eyes went crazy trying to manage my depth perception. It was not fun! When I mentioned it to the examiner she said, " Oh yeah, lots of MS patients have trouble with this carpet."

    I wanted to say, then change the dang carpet! But I didn't. (They have since changed that carpet.)

    Anyway, I can understand your curiosity and concern. Not having spatial awareness messes with your mind and your confidence. Hopefully, it will clear up for you and if not, maybe a trip to the ophthalmologist would be helpful. My glasses now have prisms in them to help my eyes work together, and it helps.
    Echo
    DX 2007 Started Ocrevus on 2/14/2018

    "Some where over the rainbow...."

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      #3
      Originally posted by TaoWarrior View Post
      The other day we had a job where the steps and the driveway were made out of the same stone pattern. I stumbled and nearly fell 3 different times because I couldn't tell where the steps started and stopped.
      Maybe it will make you feel better to know that it isn't just you. That very issue of not knowing where stairs start and stop because they all look the same applies to pretty much everybody under the right conditions.

      That's why building codes require that all public access and industrial/business stairways have obvious markings on the top and bottom treads to indicate where the stairway starts and stops. And for the stairs in between, all treads and risers must be a uniform size and shape so there are no perceptual surprises.

      Originally posted by TaoWarrior View Post
      It is not something I ever noticed before
      It could just be the first time you were in a situation where there really weren’t enough visual cues available to allow you to tell one step from the other. It might not be that you didn't recognize a visual cue. It could be that there were no visual cues there to recognize.

      Originally posted by TaoWarrior View Post
      I remember reading once how cats judge distance by the pattern of the surface and that is kind of what it was like to me.
      Pattern is not the right word for what the brain (in any mammal, so the cat story was wrong) uses to perceive and judge depth. And besides that, pattern recognition is a completely different perceptual skill.

      By definition, a pattern is something that repeats in a predictable order. If anything, some patterns act as camouflage because everything looks the same. The brain can’t perceive depth if everything looks the same.

      For example, consider a stairway covered in plaid carpeting. Plaid is a pattern you can easily recognize. So there’s nothing wrong with your pattern recognition. Yet you could still trip on the stairs because the pattern, which you recognize, looks exactly the same on every stair and you can’t tell them apart.

      You said the same thing about the stone pattern on the steps and the driveway:
      Originally posted by TaoWarrior View Post
      the steps and the driveway were made out of the same stone pattern
      In order for you to know that the steps and the driveway had the same pattern, your pattern recognition has to be intact. There’s no indication of a problem there.

      Originally posted by TaoWarrior View Post
      Going down was worse than up since I was looking down on a uniform pattern going up there was a break at each step rise so it was easier.
      That’s how the brain visually perceives and judges depth. The brain perceives depth because of the recognition of differences, not the recognition of patterns.

      Going down, there wasn’t anything wrong with your pattern recognition. The problem was that the pattern was the same and there was no visual cue that there were individual steps there. Going up, your brain was able to perceive depth because there was a break – a difference -- at each rise. In order for you to have depth perception, there first has to be something there that can be perceived.

      In the kind of depth perception that comes from both eyes working together, the brain perceives a slight difference in spatial location caused by the space between the two eyes.

      But there are other visual cues to depth the brain gets from only one eye – differences in size, color, contrast, brightness/darkness and overlap. Because of this, people with only one functioning eye still have depth perception. (It’s not as good as binocular depth perception, but it’s quite functional.)

      That’s how the art of trompe l’oeil works. Shadings and variations in color saturation and other visual cues make a flat, one-dimensional painting appear to the brain to be three-dimensional. That's nice with art, but can be bad if someone gets in impulse to act based on perceived depth that isn't actually physically there.

      It sounds like the lighting on the stairs and driveway in the downward direction was uniform, so there weren’t enough differences in light and dark or color for you to be able to see any difference between the steps. Remember, that’s the purpose of the building codes that require top and bottom stairs to have obvious markings. If each step had been marked with something visually different, you wouldn’t have had any trouble identifying them.

      In the upward direction, the lighting was different, and it allowed you to see a shading or color difference at the step risers that allowed you to tell the steps apart and at different distances and depths. That shows you that your depth perception is working.

      It’s possible that your episodes of ON have diminished your contrast and/or sensitivity, and you weren’t able to see subtle shading differences between the steps that other people can see. Your brain needs to receive visual cues in order for it to perceive depth from them. But in this case, it sounds more like there weren’t enough cues there to begin with.

      And in the same way pattern recognition isn't the skill involved in depth perception, tripping over something because it wasn't seen doesn't have anything to do with a problem with balance.

      As disconcerting as this episode was for you, it sounds more like it was the suddenness with which you became aware of normal phenomena rather than there being anything significantly wrong with your depth perception or balance.

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        #4
        Thanks Jreagan,

        That sounds like exactly what happened so it does make me feel better. The other tech was with me on that job because it was a big one (5 fireplaces going into 1 house) and he commented on my repeated stumbling which made me more aware of it.

        Of course I was backing up the steps the first couple times while he was walking up forward so even if all senses are working and it was normal he would have seen things differently. Also of course I was the one walking backwards with the load up the steps which is tricky even baring all the other issues with that house.

        Echo,

        Thanks for your encouraging words. I am due my annual eye exam next month so I may have them double check my glasses but I suspect it was just one of those situations even a non-MS'er could have had issues with.
        Rise up this mornin, Smiled with the risin sun, Three little birds Pitch by my doorstep Singin sweet songs Of melodies pure and true, Sayin, (this is my message to you-ou-ou

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