Warning: call_user_func_array() expects parameter 1 to be a valid callback, no array or string given in /home3/linda/public_html/straydogscampaign.com/wp-includes/class-wp-hook.php on line 298
Donations
Both PayPal and the Donation button charge us a fee for each donation. Sometimes its more economic to donate by bankwire
Subscribe to our newsletter

your name (required)

Your E-mail (required)

Dogs looking for friends

IBAN NL62INGB0004011891 BIC / SWIFT-Code: INGBNL2A ING Bank-Amsterdam. ActieZwerfhonden Zonnemaire The Netherlands

Canine vision

Summary

Dogs are red-green color blind. They see a brighter and less detailed world when compared to humans. Peripheral vision is better than humans (dogs see more of the world), but distance is not judged quite as well. Dogs excel at night vision and the detection of moving objects.
Figure 1 is a rough guesstimate of what a dog and human might see when viewing a color band (the electromagnetic spectrum).

dogvis
figure 1

These differences in visual ability make sense in light of evolutionary theory. Good depth perception and visual acuity are necessary for a primate (from which humans evolved) jumping from tree limb to tree limb. Good color vision enabled this primate to choose the ripest and most nutritious fruit. The canine, on the other hand, is well adapted as a nocturnal hunter of camouflaged prey.

Particulars

1. Color

Dogs see something like a human deuteranope, that is, they are red-green color blind (occurs in 4% of male humans). Simply put, this is due to having only 2 cone types rather than 3 (light
sensitive cells include cones and rods).

Detail or Acuity

Since dogs have no fovea (or area with 100% cones), their estimated eye for detail is (roughly) 6 times poorer
than in an average human.

Night Vision

Dogs have much better night vision for
2 reasons:

°The have more rods (which enable night vision).

°They have a structure called the Tapetum Lucidum

This is a reflective surface behind the retina (area including the light
sensitive cells) that reflects light back through it (gives the eerie
shine at night).

Sensitivity to Movement

Dogs are better able to detect movement.

5. Depth & Field

Figure 2 show the field of view of a human and a dog. Due to the placement of the 2 eyes, humans have an overlap of the field of each eye of 140; in dogs, it is about 100.

figure 2
dfield
This results in the dog having limited ability to accommodate focus on items at different distances), but a wider overall field allowing
them to see more of the world.

This article first appeared on http://www.uwsp.edu/psych/dog and was placed on our website with the kind permission of the
author Mark Plonsky, Ph.D.