Estimation of distance, time

Stand a half-step away from a blank wall and stare at it. Note how far away the wall seems.

• This is not a normal thing to do, people do not like staring at blank walls.
• It makes me feel slightly dizzy.

Now raise your hand and touch the wall. Was it where you expected?

I usually find there's some discrepancy. The effect would be most pronounced if the wall had absolutely no texture, not even a slight roughtness to the paint. The eye can not estimate the distance to a blank surface because there are no points of reference to compare using binocular vision, no optimal focal depth, and no shapes that can be compared to past experience to work out their distance.

Buildings with large blank walls make me feel queasy, sometimes to the extent of having to go and lie down. Too many straight lines can also be problematic, my eyes tend to glide along them unsettlingly. I prefer environments that have lots of irregular shapes and patches. These give the eye points of reference, and therefore a better sense of the space's dimensions.

Might it not be similarly difficult estimate the passage of time in a still, quiet space, or a space filled with a featureless sound such as white noise?

Suppose we do estimate the passage of time from our environment. Further suppose we have some kind of mental clock rate (see my essay on over-clocking). In a temporally featureless environment our clock rate might drift fast or slow. If it drifts too fast, we might become anxious. If it drifts too slow, we might start blanking out. Or something. Not likely to be good in any case.

Some things that could be used to judge the passage of time:

• Music with a beat, especially if you have heard it before and know how fast it goes. A metronome would also suffice.
• Walking. If you are bouncing along like a balloon you're probably clocked pretty high. If you are taking leaden steps, you're probably clocked pretty low. (this can also be applied to other physical activities)
• Driving. You know your speed from the speedometer (or as a passenger from your knowledge of road rules and from passing signs). You can compare this to the rate objects are passing to infer your own clock rate.

Perhaps this is part of why these activities are popular, especially to "unwind".

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