# What Do Rats See?
By studying rats' eyes and behavior, scientists have a pretty good idea of how a rat sees the world. In a nutshell, rats are dichromats: they perceive colors rather like a human with red-green colorblindness, but their color saturation may be quite faint, and color appears to be far less important to them than brightness. Rat vision is quite blurry, around 20/600 for normally pigmented rats. Albino rats, however, are probably blind or severely visually impaired, with about 20/1200 vision.
Human and rat retinas have two types of light receptors: cones are sensitive to bright light and color, and rods are sensitive to dim light and cannot see color. Human and rat retinas differ, however, in the types and density of cones in the retina, which has implications for color vision.
*Color vision in the retina:* Humans have three types of color cones in our retinas. We have "trichromatic" vision, consisting of short-wavelength "blue" cones, middle-wavelength "green" cones and long-wavelength "red" cones.
Rats have just two types of cones (called "dichromatic" vision): a short "blue-UV" and the middle "green" cones (Szel 1992). The "green" cones' peak sensitivity is around 510 nm (Radlwimmer 1998), but the "blue" cones are shifted toward even shorter wavelengths than human blue cones, peaking at 359 nm. This means rats can see into the ultraviolet, they can see colors we can't see (Jacobs et al. 1991; 2001).
About 88% of a rat's cones are the middle "green" type, and 12% are the long blue-UV cones (Jacobs et al. 2001), the blue-UV cones are located in a zone at the bottom of the retina (Szel et al. 1996). For more on how ultraviolet and red-green color vision evolved, see Shi et al. 2001; Yokoyama and Radlwimmer 1999, 2001; Shi and Yokoyama 2003.
*Color perception:* So, the rat's retina is sensitive to greens and to blue-ultraviolet. Can the rat actually perceive different colors, and distinguish between them? For a long time, rats were throught to be completely colorblind (e.g. Crawford et al. 1990). Recent behavioral experiments, however have shown that rats can indeed perceive ultraviolet light, and with training can distinguish between ultraviolet and visible light, and between different colors in the blue-green range (Jacobs et al. 2001).
What would such vision look like? Animals with red-green colorblindness would be able to distinguish blues from greens, but reds would appear dark to them. They would also have a "neutral" point in the blue-green area of the spectrum: they cannot distinguish these blue-green hues from certain shades of gray. The rat's color vision merges into the ultraviolet, however, so they can see ultraviolet shades that we cannot (see flowers under ultraviolet light to get an idea of what UV looks like).
Rats don't have many cones, though -- 99% of the rat retina consists of rods, which sense only light and dark, and only 1% consists of cones (LaVail 1976), compared to a human's 5% (Hecht 1987). So the rat's perception of color may be fainter than ours, and color cues may not be very important to rats. In fact, brightness appears to be far more important to rats than color. It is easy to train rats to behaviorally differentiate brightnesses, but difficult to train them to behaviorally differentiate colors (Jacobs et al. 2001).
[Rat Sensory World](http://www.ratbehavior.org/RatVision.htm#RetinalColorVision)
Also see: [What is a Visible Light?](https://byjus.com/physics/the-electromagnetic-spectrum-visible-light/)
By studying rats' eyes and behavior, scientists have a pretty good idea of how a rat sees the world. In a nutshell, rats are dichromats: they perceive colors rather like a human with red-green colorblindness, but their color saturation may be quite faint, and color appears to be far less important to them than brightness. Rat vision is quite blurry, around 20/600 for normally pigmented rats. Albino rats, however, are probably blind or severely visually impaired, with about 20/1200 vision.
Human and rat retinas have two types of light receptors: cones are sensitive to bright light and color, and rods are sensitive to dim light and cannot see color. Human and rat retinas differ, however, in the types and density of cones in the retina, which has implications for color vision.
*Color vision in the retina:* Humans have three types of color cones in our retinas. We have "trichromatic" vision, consisting of short-wavelength "blue" cones, middle-wavelength "green" cones and long-wavelength "red" cones.
Rats have just two types of cones (called "dichromatic" vision): a short "blue-UV" and the middle "green" cones (Szel 1992). The "green" cones' peak sensitivity is around 510 nm (Radlwimmer 1998), but the "blue" cones are shifted toward even shorter wavelengths than human blue cones, peaking at 359 nm. This means rats can see into the ultraviolet, they can see colors we can't see (Jacobs et al. 1991; 2001).
About 88% of a rat's cones are the middle "green" type, and 12% are the long blue-UV cones (Jacobs et al. 2001), the blue-UV cones are located in a zone at the bottom of the retina (Szel et al. 1996). For more on how ultraviolet and red-green color vision evolved, see Shi et al. 2001; Yokoyama and Radlwimmer 1999, 2001; Shi and Yokoyama 2003.
*Color perception:* So, the rat's retina is sensitive to greens and to blue-ultraviolet. Can the rat actually perceive different colors, and distinguish between them? For a long time, rats were throught to be completely colorblind (e.g. Crawford et al. 1990). Recent behavioral experiments, however have shown that rats can indeed perceive ultraviolet light, and with training can distinguish between ultraviolet and visible light, and between different colors in the blue-green range (Jacobs et al. 2001).
What would such vision look like? Animals with red-green colorblindness would be able to distinguish blues from greens, but reds would appear dark to them. They would also have a "neutral" point in the blue-green area of the spectrum: they cannot distinguish these blue-green hues from certain shades of gray. The rat's color vision merges into the ultraviolet, however, so they can see ultraviolet shades that we cannot (see flowers under ultraviolet light to get an idea of what UV looks like).
Rats don't have many cones, though -- 99% of the rat retina consists of rods, which sense only light and dark, and only 1% consists of cones (LaVail 1976), compared to a human's 5% (Hecht 1987). So the rat's perception of color may be fainter than ours, and color cues may not be very important to rats. In fact, brightness appears to be far more important to rats than color. It is easy to train rats to behaviorally differentiate brightnesses, but difficult to train them to behaviorally differentiate colors (Jacobs et al. 2001).
[Rat Sensory World](http://www.ratbehavior.org/RatVision.htm#RetinalColorVision)
Also see: [What is a Visible Light?](https://byjus.com/physics/the-electromagnetic-spectrum-visible-light/)
There are no replies made for this post yet.
Be one of the first to reply to this post!
Be one of the first to reply to this post!
