Monday, August 19, 2019

Natural Night Vision Essays -- Biology

Admit it, night vision is an ability that we would all enjoy having. Who would not want to be able to see the world at night without the use of fancy instrumentation, like night-vision goggles? Unfortunately, humans become colorblind at night because their eyes switch from normal daytime vision to a color-insensitive rod system. Unlike humans, a lot of other animals have the ability to see in the dark. This nocturnal ability is a major subject of research because scientists want to know what causes it, what methodology lies behind it, and what limitations there are. Alnut Kelber, Anna Balkenius, and Eric. J. Warrant studied the night-time vision of a nocturnal hawkmoth, Deilephila elpenor. They wanted to know if the hawkmoths can truly see colors at night, or if they are using other means to find the right kind of flowers to feed from. For example, humans cannot see colors at night and therefore have a harder time differentiating between objects using vision alone. However, a person could find food in a dark room using his or her other senses, such as smell or taste, or could rely on colorless vision to choose food based on its shape. The scientists tested a series of experiments to show that hawkmoths use color-vision at night, as opposed to reverting to their other senses like humans do. Deilephila elpenor moths were trained to associate a sugar reward with a color, either blue or yellow by feeding from colored artificial flowers at a light intensity equivalent to late dusk. Deilephilia Elpenor Moth The moths were tested (without a sugar reward) at five different light intensities ranging from mid-dusk to dim starlight, to see if they could pick the training color from eight different shades of gray... ...we have a limited field of vision, and we can’t see in the back of our head. Continuous Visual Stream humans only get one shot to allow their photoreceptors to see an image, the images come through the eyes into the brain in a constant stream and are lost almost immediately, not stored. Advantages brain power that could be used to store up images to help see color in the dark can instead be used to make a clearer, better-resolved picture Disadvantages humans need more light to see color Photoreceptor Types humans also have 3 types, but: red, blue, and green Advantages we have trichromatic vision, which helps us differentiate objects and appreciate aesthetically pleasing sights Disadvantages we can’t see in the UV spectrum, and there are other animals such as butterflies which have 4 or 5 different photoreceptor types and can see more colors than us

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