Whenever I’m in a vehicle that’s zipping down the interstate in open country, I notice something curious when I look out my side window: Things that are close in distance (barns, cornfields, cows, shredded semi tires) zip past in a backward direction, as you’d expect. However, things further away (mid-field of vision to the horizon line), appear to travel in a forward direction, more or less trying to keep up with me. I always thought this was pretty weird since you’d figure everything would appear to travel in a backward direction, and probably why it’s a good idea to lay off the drugs when you’re driving during the daytime at least. So, why does this happen?
It’s optical flow.
I would have said it’s parallax: the displacement or difference in the apparent position of an object viewed along two different lines of sight. The effect is pretty clearly demonstrated in the animation included near the top of that Wikipedia article.
It’s psychological. Everything does “move backwards” but it’s only apparent for close objects. The further away something is, the less the angle of view is changing and your brain interprets this lack of change (and/or possibly their apparent change of position relative to the foreground objects) as the objects moving along with you.
Yes, it’s simply that more distant objects appear to be passing by (“backwards”) more slowly than closer objects. So, relative to those closer objects, they’re moving forwards.
Really distant objects, like, say, the moon or a bright star, appear not to be moving at all, to the extent that they can seem to be following you - resulting in plenty of UFO sightings…
I had no idea what you were talking about until I reached the words “trying to keep up with me.” That’s when I realized you’re describing the same illusion as when the sun or stars seem to follow us no matter how far we go or which way we turn.
I don’t know the technical description, but I understand the cause of it to be our expectation that we WILL pass it, just like we pass everything else. But logically, because it is so distant, we never do pass the object. Our minds aren’t so logical, and if we aren’t passing it, the brain decides that it must be keeping us with us.
Someone needs to mention angles.
I was obsessed with this question at age 3 or 4. Played with blocks and legos representing various objects and a popsicle stick representing the car to figure out that I was watching blades of grass, fenceposts, and hedge trees that were very close together rush by, while the things I saw moving more slowly were all larger and farther apart objects like cows, big trees, and farmhouses.
Smart move. Keep the intoxicated driving for the nighttime. Safer in every measure.