Welcome to Natural Wonders! I hope you’ve had a chance to get outside and explore — when life gets busy or depressing or overwhelming, remember that getting outdoors can bring you back to yourself. There’s good research that supports the calming effects of greenspace. I hope you have a chance to enjoy it!
A couple more factors that influence depth perception. The distance between the eyes must influence the perceived depth. When the eyes are very close together, their effectiveness at depth perception is probably limited. It would be interesting to find out how this plays out in the animal world. How close can eyes be and still deliver binocular depth perception? Binocular depth depends on the difference between the images falling on the right and left eyes, and when these are very close together, the image differences would be small. The second factor is that distance (depth) can be estimated with a single eye by parallax, and a lot of birds (e.g. doves, chickens) seem to do that by moving their heads back and forth, especially while walking. Close objects then appear to move across a larger segment of the visual field than distant objects. It's easy to confirm this effect for oneself. Parallax might be more important for birds that have eyes on the sides of their head, and/or that move faster.
When I was diving off the coast of Venezuela, the guide told us that the sea gulls slam down into the water on one side of their body , especially eyes, causing eventual blindness and that they could no longer see to accurately catch fish and eventually fly away and die of starvation. After reading your article, I wonder if his information was true.
A couple more factors that influence depth perception. The distance between the eyes must influence the perceived depth. When the eyes are very close together, their effectiveness at depth perception is probably limited. It would be interesting to find out how this plays out in the animal world. How close can eyes be and still deliver binocular depth perception? Binocular depth depends on the difference between the images falling on the right and left eyes, and when these are very close together, the image differences would be small. The second factor is that distance (depth) can be estimated with a single eye by parallax, and a lot of birds (e.g. doves, chickens) seem to do that by moving their heads back and forth, especially while walking. Close objects then appear to move across a larger segment of the visual field than distant objects. It's easy to confirm this effect for oneself. Parallax might be more important for birds that have eyes on the sides of their head, and/or that move faster.
When I was diving off the coast of Venezuela, the guide told us that the sea gulls slam down into the water on one side of their body , especially eyes, causing eventual blindness and that they could no longer see to accurately catch fish and eventually fly away and die of starvation. After reading your article, I wonder if his information was true.
Laura L.