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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 ...
Hearing range. Hearing range describes the frequency range that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher ...
The LEA Vision Test System is a series of pediatric vision tests designed specifically for children who do not know how to read the letters of the alphabet that are typically used in eye charts. There are numerous variants of the LEA test which can be used to assess the visual capabilities of near vision and distance vision, as well as several ...
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 ...
Humans have a slightly over 210-degree forward-facing horizontal arc of their visual field (i.e. without eye movements), [5] [6] [7] (with eye movements included it is slightly larger, as you can try for yourself by wiggling a finger on the side), while some birds have a complete or nearly complete 360-degree visual field. The vertical range of ...
Visual acuity is a parameter that is frequently used to assess overall vision. However, diminished contrast sensitivity may cause decreased visual function in spite of normal visual acuity. [11] For example, some individuals with glaucoma may achieve 20/20 vision on acuity exams, yet struggle with activities of daily living, such as driving at ...
Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal. In visual neuroscience, spectral sensitivity is used to describe the different characteristics of the photopigments in the rod cells and cone cells in the retina of the eye.
Touch. The absolute threshold for touch is a bee's wing dropping onto a person's cheek from one centimeter (0.4 inches) away. Different parts of the body are more sensitive to touch, so this varies from one body part to the next (20). As people age, the absolute threshold for touch becomes larger, especially after age 65.