2.ERGO-INFERG - ERGONOMICS INFORMATION ERGONOMICS...

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ERGONOMICS INFORMATION ERGONOMICS
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2 INFORMATION INPUT PROCESSES Human beings receive stimuli from many resources People can sense those level of stimuli that are within the spectra to which they are sensitive Five classic senses (vision, audition, smell, taste, and touch) are known as the exteroceptors Proprioceptors are stimulated by the actions of the body itself, such as a reach or a sudden turn. They are embedded within the muscles and tendons, around the joints, and in the inner ear.
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3 The external stimuli that are within the sensitivity ranges excite the appropriate exteroceptors on a selective basis. There is difference between what is sensed and what is perceived. Perception differs from sensation in that perception involves attaching meaning to stimuli A special category of the proprioceptors is the kinesthetic sense
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4 THE EXTEROCEPTORS Eye Light is visually evaluated radiant energy People require 80% of the information through the visual channels Six muscles attach to the eyeball move the eyeball Cones provide color, daylight vision. Cones are more sensitive to some wavelengths of light than others. Rods provide black and white, night vision. Rods are more sensitive to light than are cones.
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5 Violet Blue Green Yellow Orange Red Gamma rays X-rays Ultraviolet rays Infrared Radar Radio waves AC Wave length (m) 10 -14 10 -12 10 -8 10 -4 10 -2 10 4 10 8 Visible spectrum 308 500 600 700 800 (nm) 1 nm = 10 -9 m
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6 EFFECTIVENESS OF VISUAL FUNCTIONING Internal Factors Visual Acuity: It is the sharpness of vision It depends on several factors, including the shape of the eyeball and the flexibility of the lens Snellen scale 20/100 (poor vision) indicates that the person being checked can see a detail from 20 m whereas a person with perfect vision can see the same detail from a distance of 100 m 20/15 vision is better than perfect since a detail that can normally be seen at a distance of 15 m can be detected by the subject at a distance of 20 m.
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7 Depth perception: It is the ability to see depth Person sees an object with two eyes, thus from different angles, allows one to see depth An observer uses pictorial, kinetic (motion parallax), and physiological cues in perceiving depth If a job requires the ability to see depth, it is a normal expectation that the workers assigned to that job have adequate depth perception Can you name a job?
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8 Near point of accommodation: As an object is brought close to the eyes, after some point, the object will be seen as two objects. This point is known as the near point of accommodation. Phorias: When one looks at an object, the two eyes converge on the object so as to form the two images on the corresponding positions on the two retinas. The two images are fused and one sees only one object Some people’s eyes converge too much, some tend not to converge enough People with phorias do not see double images.
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2.ERGO-INFERG - ERGONOMICS INFORMATION ERGONOMICS...

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