What Colors do Horses See?

I once conducted a scientific project inquiring which colors lovebirds could differentiate between. I thought it ideal seeing as I liked animals, our family owned a small flock of lovebirds, and I had never seen the question answered. I would have won first place if I had not been very sick on the day the judges conducted interviews. I do have red ribbon for my hard work. Not bad for sixth grade, ey?

Can horses pick up different colors? Yes. A journal study was conducted in which scientists conducted tests – approved by the Institutional Animal Care and Use Facility of the University of Wisconsin-Madison – to illicit responses from the receptors in the eyes of six ponies. Another is a study was conducted by Tania Blackmore, a graduate student at the Department of Psychology at the University of Waikato. This was a research study she conducted for her Masters thesis in which a special stall with colored treat prompts was constructed in order to Measure results from four horses. These studies showed that horses can differentiate colors on a dichromatic scale whereas humans and other primates perceive on a trichromatic color scale.

What is the difference?

click image to see more interpretations

This is the trichromatic color scale that humans and other primates perceive with cone cells in their eyes. Cone cells are photoreceptors that perceive different wavelengths which we identify as colors. Our photoreceptors take in three primary colors: red, blue, and yellow – and four basic hues, red, blue, yellow, and green. The differentiation in our scotopic vision varies between people, hence the disagreements over the grade of red or blue an object appears to be.

click image to see original study
click image to see original study

Dichromatic vision as experienced by horses features blue and yellow photoreceptive cone cells. Neither of the referenced studies are sure if horses can see the green hue between yellow and blue. This perception  would be similar to a person who is color blind to red and green hues:

click image to see original study
click image to see original study


Figures A and B show unaltered images as we would perceive them. Figures C and D show the same images as a horse would seem them. As you can see though the images are clear the color creates a blurred effect in figures C and D. This would also explain why horses will react differently to things than we would, especially if they do not understand what they are seeing. This is also why horses have to use all their senses to perceive the world around them – touch, smell, sight, sound, and taste~

Until next week, happy exploring!


Other Ratified Research Posts:

  1. People, Horses, and Halitosis
  2. The Headless Horseman
  3. The Luckdragon
  4. (more coming soon)

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