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Vision is the most important sense for birds, since good eyesight is essential for safe flight. Birds have a number of adaptations which give visual acuity superior to that of other vertebrate groups; a pigeon has been described as "two eyes with wings". [ 1] Birds are theropod dinosaurs, [ 2][ 3] and the avian eye resembles that of other ...
Tetrachromacy. The four pigments in a bird's cone cells (in this example, estrildid finches) extend the range of color vision into the ultraviolet. [ 1] Tetrachromacy (from Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types ...
Avian brain. The avian brain is the central organ of the nervous system in birds. Birds possess large, complex brains, which process, integrate, and coordinate information received from the environment and make decisions on how to respond with the rest of the body. Like in all chordates, the avian brain is contained within the skull bones of ...
Flicker fusion threshold. The flicker fusion threshold, also known as critical flicker frequency or flicker fusion rate, is the frequency at which a flickering light appears steady to the average human observer. It is a concept studied in vision science, more specifically in the psychophysics of visual perception.
Binocular vision. Principle of binocular vision with horopter shown. In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an animal has eyes on opposite ...
A bird's-eye view is an elevated view of an object or location from a very steep viewing angle, creating a perspective as if the observer were a bird in flight looking downward. Bird's-eye views can be an aerial photograph , but also a drawing, and are often used in the making of blueprints, floor plans and maps.
Blindness in animals. Visual perception in animals plays an important role in the animal kingdom, most importantly for the identification of food sources and avoidance of predators. For this reason, blindness in animals is a unique topic of study. In general, nocturnal or subterranean animals have less interest in the visual world, and depend ...
An example of the Landolt C eye chart (also known as the Japanese eye chart.). Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision, while the ETDRS chart is designed for use at 4 meters. [16]