I’ve been searching the web for a while trying to find statistics on how far an average human can see. I’ve found this information for dogs, of all things, but not humans, even after wrestling with multiple search engines (including multiple rewordings of my question at www.ask.com)..)
What I need to know is, in clear weather and average outdoor lighting, at what distance can a human with 20/20 vision distinguish between man-sized objects and creatures. I would prefer both ranges - that is, for being stationary and for being in motion(typically a longer range than stationary)- but either would be fine, as long as I can find this out.
I don’t technically need indoor ranges (want is another matter) but if those are different than outdoor and could be provided, that would be an absolutely super bonus.
Thanks in advance.
Brains! Once an illithid gets its first taste of “the other white meat,” there’s no going back.
G’ah… a couple things. First, it autolinked that url on me… it should be www.ask.com instead of that thing it did. Secondly, the stationary and in-motion are in reference to the viewee (the object or creature being looked at), not the viewer (I’m assuming the viewer is stationary). Thanks again.
The normal human eye’s resolution/acuity (last column) is about 60~/deg (spatial frequency in the arc of vision). If 2 nude black people, each 1.5 ft wide, are standing 1.5 ft apart, against a white wall – or 2 nude white people, each. . ., against a black wall (Now why would they be doing that?) – the figure of 60~/deg gives you a chance at distinguishing them at:
d = [60/tan (1 deg)]21.5 = 10, 309 ft = ~2 mi
, but only when there’s no blizzard and the sun is not baking the earth to produce air-convection waves, etc. Clearly (so to speak) the answer grossly depends on the target’s contrast and the state of the medium.
I don’t think, for that small an angular target (1 min), the optic nerve’s motion detection would kick in, so I think motion of the target relative to its background would only lessen the distance at which one could distinguish the same size target.
Ray (That’s the straight dope. Now, if you can see around corners. . .)
This seems like a reasonable place to post this. Does the architecture of the eye (i’m, thinking particularly of people of chinese/oriental descent) affect the field of vision?
Andy, I can’t cite this, but the archetecture of the eye does effect vision, but shouldn’t alter distance. Resolution (what measures distant viewing) is a function of the spacing of the rods and cones, and the focusing ability of the cornea (ie shape of the eye). Numerous PBS specials have discussed the shaping of the face and eye socket (not eye) between races and it is usually a reaction of the peoples environment. It will alter the lateral and vertical range of vision, and glare sensitivity, but not resolution.
The info above must be taken with a grain of salt. The definition of a “normal” eye is important. Is it considering a 20/20 vision eye, or the ‘average’ eye. The latter having poorer vision. Also the size of an eye is not constant and bigger eyes will have different characteristics than a smaller one. “Normal” is a loose term and it would behoove you to analyze the definition of such before making any definative proclimations.
Thank you. However… 2 miles doesn’t sound right. It sounds waaay too far. I read a study that indicates dogs can only see to about ~550 meters for stationary and ~750 meters for in-motion. While you might see large trees at 2 miles, I don’t think you could see a person. Take the example of going up in an airplane… even at 1 mile I bet you wouldn’t be able to see people (I can’t) and that even cars are hard to spot.
Ah well…
Brains! Once an illithid gets its first taste of “the other white meat,” there’s no going back.
This topic touches on a related question I wanted to ask a while back but never found time for. So while we’re at this, how does the vision of humans rate against the animal kingdom in general? I am thinking of the aspects of color, detail, and distance (near and far). From watching enough Nova and Nature on PBS, I know that some birds of prey have truly amazing long distance sight, and that many other animals, such as dogs, seems to have very poor color vision. Thus I’ve formed the idea that we have very excellent color vision with good detail at middle distances compared with the animal kingdom, but I’ve never done the research to prove or disprove this.
Micro, I can say from experience (private pilot) that you most certainly can make out people milling about on an airfield from distances well over a mile, likely nearing 2+ miles for moving people. A pilot will frequently operate at near 4,000 feet vertical altitude, and you can see personel walking around the airfield from distances, you could do the geometery and figure a mile or two of horizontal distance. Granted this is a person wearing contrasting colors (usually bright orange) against a dark consistent airfield. I have better than 20/20 vision, and believe that a 2 mile range is conservative, but your milage may vary.
Bus, good question, but it will need to be answered in parts. I would argue that people have the best overall vision in the animal kindom, hands down. The caveat being the use of the word overall. Birds of prey have exceptional vision at distance, and pack factors more rods and cones in their eyes than humans, but it has been shown they are nearly blind at short distances. Owls and Eagles attack their prey from above, but when they strike the prey, they rely on their ears to narrow it down if they miss. I saw a demonstration where an owl was filmed at high speeds striking a mouse in cover, it hit the mouse, but the mouse managed to slide out of its grasp. The owl then sat, unaware of the mouses location, until the mouse started to try and scurry away, then the owl was able to jump again to kill it. It demonstrated that the owl couldn’t resolve the object at short distances. Another factor in quality of sight, is the brains ability to decipher the optical images. Humans are unparalleled in this aspect, and I speculate than many animals are limited by the amount of gray matter dedicated to reading the impulses rather than by the size of the eye. Also many animals with good eyesight can’t see well in color, if at all, the practical applications of this are relative, but it is a important factor. Humans see well over a broad range of uses and by nature are very adaptable, animals more commonly develop specialized faculties, and can surpass humans in one or two catagories but in a visual decathalon humans I suspect are unmatched.
Thank you for your input. I’ll go with Nano’s earlier estimate then for an average person with 20:20 vision. Guess it’s time for me to go in for that lazik surgery.
What about squid, which communicate with light and color? I think I remember seeing somewhere that squid have the most highly developed eyes in the entire animal kingdom. Maybe I’m wrong though, if I was wrong about the visual range.
Again, thanks for your input.
Brains! Once an illithid gets its first taste of “the other white meat,” there’s no going back.
I apologive in advance for so horribly deviating from the original topic, but this does relate. I can’t answer the original question, but as far as the “visual decatholan” is concerned…
All animals have organs, including eyes, that have evolved to complement the way in which they live. We cannot say we have the very best vision in the animal kingdom. We may only say we have the best vision in the animal kingdom for living a HUMAN lifestyle. If a human was given a barred owl’s body, but with a human visual system, and sent to live as an owl, it wouldn’t last two weeks.
We cannot hold a “visual decathalon”. Because all animals are so different in lifestyle, there can’t be any kind of test or series of tests to rate all animal’s visual abilities on the same level. There are almost certainly uses for and aspects of vision that we, as humans, can’t even BEGIN to imagine.
The way in which we rate vision is hugely biased–the description Omniscent wrote glaringly overlooked several details. We have only begun in the last decade or so to realize that many, if not most, animals with eyes comparable to our own (ie, that have the vertebrate eye) can see ultra-violet light. Our lack in this ability would certainly make us lose in the “visual decathalon” in the same way that our small hearing range would be devastating to us in an “auditory decathalon”. Did anyone consider that?
I have two words I want all of you to look up in an unabriged dictionary:
anthropomorphism
anthropocentrism
They may shed some light onto my meaning.
“Whenever a man hears it
he is young, and Nature
is in her spring;
whenever he hears it, it
is a new world and a free
country, and the gates of
heaven are not shut
against him”
–Thoreau, on
the song of the wood thrush
In my psychology book, they mentioned that the human eye is sensitive enough to see a candle flame from thirty miles away. I can’t believe that number, even if you were in a pitch black environment which I assumed they were implying, there wouldn’t be enough photons hitting your retinas.
One of the interesting observations is that humans can see over a range of log14, from the dimmest we can see to the brightest light we can stand. I rembember a discussion about whether the human eye can detect a single photon but I haven’t found the source yet. I believe the answer was no.
