This is a good opportunity to educate the general [HN] community about dogs:
1. They can only see blue/yellow. Not like humans' RGB.
2. They are short sighted. For far away objects, their sight is like a T-Rex, they can see moving objects, not stationary objects. Remain still, and they can't see you. Then again, they can smell you, especially if it's downwind.
3. Their flicker fusion threshold is higher than humans. If you show them a cute mobile picture of a baby, they'll see a lot of flickering. As well, did you know lights have a flicker? If you think it's bad, it's even worse for dogs which can lead to stress.
My 12 year old labrador is in excellent shape, but his hearing is no longer quite up to scratch, and to avoid embarrassing levels of shouting when we are out and about, I increasingly use pointing and other signs at my end of our communication. Also, his left eye has been problematic for many years, and apparently only registers the haziest of outlines these days.
And yet, he contantly amazes me by the range and precision of his vision. Downwards pointing with my left arm means come here at once, which he will reliably register at a distance more than a hundred meters. Other dogs he will recognize at distances further than that, and he will unerringly home in on thrown stick bobbing on the water, as long as it's on the right, where his good eye can see.
Clearly, there's more to it than just they are short sighted.
As a nearsighted human who didn't get glasses as early as he should have, I used to use people's gait or clothing to recognize them at long distances. You know your dog best, just saying there can be ways to compensate.
Without a doubt, yes, all sorts of compensation are at play. Still, the fact remains that he reliably picks up my relatively subdued sign language at great distance. And swimming, even in rough sea, if he can't pick out the floating stick, he'll look to me, I'll point, he will scan as directed, and head straight for the thing. One way or the other, all this is decent visual performance, nothing nearsighted about it.
We all compensate for the handicaps we have. I'm also was very nearsighted since I was about 11. I did get glasses but didn't use them while skiing, not very confy under the helmet. But I could still see who of my classmates were at the bottom of the mountain, about 300 m away, because of the movement pattern. I have no clue how we know how dogs have bad eye sight, I can't even begin to imagine how we know about T-Rex. I have to look at that link someone posted.
Another dog sense I've wondered about is hearing. What is our music like to them?
Let's consider live music, first. A lot of instruments have significant harmonics well above 20 KHz. So let's say you are practicing your violin or trumpet, and your dog is in the room. The maker of your instrument took great care to get the sound right, which mainly consists of making sure that the various harmonics are at the right relative amplitudes.
Does the instrument maker take any care to get the harmonics above 20 KHz right? They don't affect how the instrument sounds to humans, so I'd expect not. That could mean that your beautiful violin has a horrible screech that only your dog hears.
How about recorded music? If my guess is right and our instruments sound bad above 20 KHz, recorded music may be an improvement from the dog's point of view, because we filter out those highs when recording.
But if live instruments do actually sound OK above 20 KHz, then to a dog our record are going to seem limited at best.
> Another dog sense I've wondered about is hearing. What is our music like to them?
This is a thing I've wondered about too. Their frequency range is only part of it. There's also the frequency weighted sensitivity; it's why we humans perceive music the way we do. A dog might be able to hear a tone at 45kHz, but it might require significant amplitude, e.g. threshold of perception at 45kHz might be 80 dB SPL. The ISO 226:2003 equal loudness contours shows that human sensitivity for high frequencies falls off very sharply after about 16kHz[1]. Looking stuff up for dogs, I'm finding mixed results, so I'm less confident in my assertion here, but it seems to me that dog hearing still falls off sharply near the upper end of it's range. From the charts I find, a dog's sensitive band seems to be wider than humans and centered higher[2], but there's still that sharp upper cutoff.
> Let's consider live music, first. A lot of instruments have significant harmonics well above 20 kHz.
This is heavily dependent on the nature of the instrument. A bass instrument like a tuba or a bass guitar isn't going to have much frequency content once it gets into the mid-to-high hundreds of Hz. A guitar is going to be done between 10-15kHz, and most of it's frequency content that defines its character is going to be down in the mid-range (mid-hundreds to low thousands of Hz). Cymbals? Yeah, I'd be in no way surprised if those contain tons of content above 20kHz that's only detectable with lab equipment or a dog's ears.
> Does the instrument maker take any care to get the harmonics above 20 KHz right? They don't affect how the instrument sounds to humans, so I'd expect not. That could mean that your beautiful violin has a horrible screech that only your dog hears.
Instruments with significant frequency content in our most sensitive bands (e.g. human voice, eletric guitar, trumpet) are often considered 'lead' instruments, and they're are also the ones where getting the frequency balance right to sound good instead of harsh is the trickiest. So, my intuition is that a similar thing plays out with dogs. Those instruments that do contain significant frequency content in the high kHz to low 10s of kHz (e.g. cymbals) are more likely to sound harsh, IMO. Something like a tuba, a dog probably cares less.
> How about recorded music? If my guess is right and our instruments sound bad above 20 KHz, recorded music may be an improvement from the dog's point of view, because we filter out those highs when recording.
> But if live instruments do actually sound OK above 20 KHz, then to a dog our record are going to seem limited at best.
My guess here is that our recordings probably sound unnaturally muffled. In my own study of recording and mixing, it seems common to filter sharply above 20Khz, or maybe a little less, because their's no sense in frying the tweeters with content nobody can hear anyway. Additionally, the DACs in modern recording gear are going to have their filters set to filter sharply above 20kHz anyway, to keep digital aliasing noise from impairing an accurate reproduction of the original analog signal from the digital one. It might not sound bad to the dog, but I'm pretty sure a dog would be able to easily tell the difference between a recording of a cymbal, and a live cymbal.
> Looking stuff up for dogs, I'm finding mixed results, so I'm less confident in my assertion here
I was kind of surprised at how little information I could find a while back when I searched online for information about animal hearing and animal vision. I was playing around with making a camera to automatically take a photo whenever an animal stopped by to eat the seeds and nuts I put out for them.
I've got a sensor that measures the distance to an object by bouncing an infrared laser off it. It's a class 1 laser, which basically means that it is not possible to exceed safe exposure by looking at it, even with a microscope or telescope. But that's for humans. What if a curious bird decided to get right up to it and take a look?
I couldn't find anything on laser safety for birds or squirrels or other animals likely to visit.
I've also got a distance sensor that uses a 40 KHz ultrasonic pulse. I couldn't find anything on the safety of that, either, for animals.
I did some tests with the IR laser and found that it didn't work very well for this application. It worked great at detecting when my hand was in front of it, but was very flaky with birds and squirrels. I guess features and fur just doesn't reflect IR light well enough.
Ultrasonic worked better, and so that's still in the running if I ever get time to finish this thing. I still don't know about safety of that for the animals, but figure that if the animal can hear it they will stay away if it is loud enough to harm them.
Alternatively, I may just go with having the camera take a photo every second, and try to figure out in software which ones have an animal in them. No risk of harming the animal that way, and also the camera could then be in my house looking out a window instead of outside, which would make power a lot easier and get rid of the need for weatherproofing it.
Technically speaking, a similar kind of solution that exists for LEDs also exist for fluorescent tubes: using high frequency ballasts that do not perceptibly flicker (not even (near)subconsciously - which is true for a lot of LED and fluorescent lights). Those are more expensive, hard to find and not the default though.
Candles generate soot, which is not good for your health. The soot will also stain walls and ceilings, similar to cigarette smoke. Natural waxes like beeswax candles have a cleaner burn, but they're very expensive.
If you're going to go non-electrical, I think an oil lamp (e.g. paraffin) is your best bet. Very cheap, safer than candles in the right lantern, and clean-burning (assuming a quality oil that doesn't have a lot of sulfur and other pollutants).
3. The flicker fusion issue mostly applies to cathode ray displays and moving pictures. Many LCDs use flickering light (PWM) for backlight, but usually at more than 200Hz. Better LCDs use linear current sources for backlight, so there's no flicker at all. An LCD should be fine even for dogs when static images are displayed.
Cheap LED bulbs actually flicker significantly, which I realized when I filmed using my camera's "slow motion" capture at 240 frames per second.
In our bedroom, I put in some LEDs, not realizing there could possibly be a difference between cheap and expensive ones. One night I filmed my cat doing something dumb in slow motion, and when I looked at the playback the whole room was strobing.
It was pretty wild. I might even still have the video, and could see about posting it somewhere.
You don't need slow motion camera, it's enough with most normal catch the worst offenders in the store if they have those led display sets where you can see the lightbulb lit. Just shove the camera real close to the lightbulb and watch the stripes. If no stripes, put it even closer (almost touching) and if it's still ok, buy it :-)
well now i’m curious, since we have a handful of LED bulbs throughout the house. they flicker no doubt, detectable through the slow motion setting on my phone camera.
any suggestions on what energy efficient bulbs to replace them with?!
There are plenty of flicker free LEDs available, you just have to check beforehand. AFAIK all Philips LEDs are flicker free now, or at least those branded as “EyeCare”.
That's interesting. We switched to LED bulbs in our living room and after that our eldest dog would not settle, I thought maybe the bulbs had a low humming noise he didn't like but it could have been a flicker instead. We switched back and he was fine again.
Or both. Some cheap LEDs have terrible high-pitched humming noises from bad AC to DC converters/transformers.
(A big reason that there's a growing movement questioning if we should have more dedicated DC wires/plugs/sockets in our homes and do AC to DC conversion once for entire circuits instead at the socket/in the plug "wall wart" for every single device. Also interesting that USB A sockets are probably the closest we have to a ubiquitous home standard actually moving in that direction.)
My wife was sensitive to the flickering of CFLs and LEDs running on AC, so we installed some dedicated 12V DC circuits in our house and they are really great. We run strings of DC LEDs from them, and they are bright and flicker-free.
You can run the lights off of 12V batteries and charge those from a few solar panels, or just have one dedicated high-quality AC-DC transformer for the DC circuits.
hmmm, the first 2 months of my (rescued) dog being in my home (a year ago) were anxiety-filled for her, and now i wonder if it was due to the led bulbs. she’s mostly settled now, realizing that home is good for sleep, though still gets nervous here and there. she likes being outside more but that seems to be true of dogs in general.
The flickering thing has always made me feel bad for my dog and dogs in general. My entire office room is monitors/TVs and I can only imagine what she sees, like a rave 24/7. But she will still sleep in here when she can go anywhere else in the house.
I actually got curious about this a year ago when I got a dog and she was watching me paint a wall. I made an iOS app* that allows you to see the color spectrum a dog sees, as well as take video and photos.
Some weekend I hope to make enough time to add something to represent the short sightedness using image depth data as well as a few other features I would like to add.
I actually had not heard about the flicker fusion threshold being different, thanks for the links!
The funny thing with my dog, who we've done some scent work with, is that his nose seems to need to be focused and 'switched on' to really work.
If I throw him a treat and he misses it, he will default to looking around with his eyes and missing it until I point it out. But give him the ready cue, and he can find a tiny piece of food or odour hidden in a drawer in a room in under a minute.
So my take on that is it takes a lot of processing power to run the nose, and after a search session it's definitely nap time.
And side note, I'd like to see AI efforts aiming at the level of a dog before we go for humans. It's amazing what they can do but it takes so long to train them and you have to start from scratch each time.
But, they might find your latent scent on the ground or on objects and follow that to you. So, being downwind at the moment is different from having a downwind approach to a new area...
So, is fluorescent lighting in an area with dogs would be bad, or not? Is there method to determine which type of lighting is best? I expect even LED bulbs could flicker based on quality of the line.
Am I wrong in assuming incandescent bulbs would be better
Incandescent bulbs flicker at the rate of the AC current, but the flickering is brighter/dimmer rather than on/off because they stay radiant while hot and cool slowly.
Yes but I guess the amplitude of the flicker must be very low? I'd have thought that if it was at all significant it would be very visually obvious at 50-60Hz
But you can stabilize the current quite nicely if you know how. This is almost never done on cheap LEDs. Except IKEA's leds, they were surpricingly good in some test lately.
I fully believe that they can also "see" scents, like a cartoon character floating to a pie on a window sill following a path of inhaled visible scent fumes, but I have no evidence of that.
1. They can only see blue/yellow. Not like humans' RGB.
2. They are short sighted. For far away objects, their sight is like a T-Rex, they can see moving objects, not stationary objects. Remain still, and they can't see you. Then again, they can smell you, especially if it's downwind.
3. Their flicker fusion threshold is higher than humans. If you show them a cute mobile picture of a baby, they'll see a lot of flickering. As well, did you know lights have a flicker? If you think it's bad, it's even worse for dogs which can lead to stress.
More:
https://dog-vision.com/
https://www.dogwalkersmelbourne.com.au/articles-dog-walking-...