Last week, a question was posed about whether dogs notice their reflection in the mirror (the short answer: yes, but they typically don’t pay attention because it offers nothing to them, and sight isn’t as important to dogs as it is to humans.)
The reader who asked about that also had more dog-related questions and, since I’ve received a lot of response to last week’s question (I’ve noticed anything animal related creates a lot of interest), I thought I’d explore those.
Q: Are dogs colorblind?
A: I’ve found several sources that basically agree on this one. A good summary is from the website, dogtime.com.
It explains that dogs see more than black, white and gray, but have a more limited color range than people.
“To put it in very basic terms, the canine color field consists mostly of yellows, blues and violets,” the article states.”
What we see as reds, greens and oranges are not distinguishable to dogs, which see them on a yellow-to-blue spectrum.
To explain why, the article states the retina has two photoreceptors: rods and cones. The human eye has more types of cones while a dog’s has more rods (providing better night vision) but no fovea, which humans have. The fovea is responsible for sharp visual details, such as colors.
Q: Can dogs tell what’s happening on television?
A: Psychologist Stanley Coren tackled this one in a June 2011 edition of Psychology Today.
Coren explains the motions on television, in simplest form, are a “moving pattern of light across the retina.”
He explains, “At the level of single cells on the retina, a moving target appears to be a flicker.”
When the flickers occur quickly enough, something called flicker fusion occurs. That basically means it looks like a steady moving picture.
For example, a fluorescent light flashes at 120 cycles of light and dark per second but looks like it glows continuously
Humans can’t see flickering above a speed of 55 cycles per second. A study conducted on beagles indicated they see flickers up to 75 cycles per second.
A television flickers at 60 times per second, so to a dog it’s more flickers than pictures so it’s not that interesting.
Staff Writer Bernie Delinski writes Just Ask, which runs Wednesdays in the TimesDaily. If you’ve got a question, e-mail it to bernie.delinski@TimesDaily.com, call him at 256-740-5739, fax it to 256-740-4717 or send it to Just Ask, c/o TimesDaily, P.O. Box 797, Florence, AL 35631.