Eli5: How do scientists determine the vision of a specific animal?
In: Biology
Often, the animals are trained to identify a color or object, rewarded for doing so, and then presented with a variety of colors and objects to see if they can distinguish between them. There was a short video floating around Reddit for a while of a chicken that had been taught to peck at a red circle to get a treat. Then, researchers mix up circles of a bunch of different colors and see if the chicken can find the red one. If the chicken consistently pecks at a different color – say, green – then it probably indicates that the chicken is unable to distinguish between those colors.
Similarly, you could train an animal to come to a target and then move a long distance away from the animal. If they can still identify the target and move towards it from that distance, it means their vision can still clearly see from that distance.
Dissecting the eyes and inspecting them also goes a long way today, since we have a plethora of tools to inspect organs and cells. Scientists can cut a section of a retina and then use a microscope to literally count the cones and rods to check their density. They can take individual cells and shine light with a specific wavelength on the cells to see if they react. Scientists can even look at the genes to find similar genes to what we know codes for certain proteins in our eyes or another, well-studied animal’s eyes, which we know are sensitive to a particular wavelength of light.
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