Why do my feet look farther away when lying down?
Question
Hello Naked Scientists,
When I lay down, my feet appear farther away from me compared to when I am standing up. I wear contacts during the day and glasses during the evening. Could this be a product of my corrective eyewear or a manifestation of my brain due to different visual reference points? Thank you.
Chris Markley
Answer
We posed this question to Dr Rebecca Lawson from the University of Liverpool...
It seems unlikely that any effects of glasses or lenses would differ depending on whether you are standing or lying down. We do seem to overestimate vertical distances particularly if we're on top of a cliff looking down it. We overestimate and think that the height of the cliff is greater than if we were at the base of the same cliff looking upwards and in fact, agoraphobics seem particularly prone to this overestimation. However, this effect goes in the opposite direction. So really, I don't have a good account of why Chris's feet seem further away when he is lying down than standing, but I think that his question really nicely shows of the complexity of human distance estimation. Perhaps surprisingly, we still don't fully understand how we judge the size and distance of objects.
Comments
Big disc, long pole
I've noticed that when an object like a pole or disc is spun, the RPM of the center is the same as the outer edge or tip, one rotation of the center point is one rotation of the outer point, but the distance and speed traveled is much greater on the outer portion than it is in the center and even greater the larger the disc or pole is. If there was a long pole floating in space with no obstructions, or a disc large enough, what would happen if it were to rotate resulting in the outer edge exceeding the speed of light?
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