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56 Cards in this Set
- Front
- Back
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Light is focused on the _____ located in the ____ of the eye...
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Retina, Back
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___ are for nighttime vision
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Rods
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___ are for peripheral vision
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Rods
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___ are for daylight vision
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Cones
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Cones are concentrated where?
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in the center of the retina
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Used for "Foveal" vision...
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Cones
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____ are used for color vision
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Cones
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Ability to perceive or discriminate detail is called?
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Acuity
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What is visual acuity?
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Ability to discriminate or perceive detail
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Where does the highest visual acuity occur?
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Highest acuity is at the fovea
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What changes shape in order to focus an image?
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The lens
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Myopia is also known as...
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Nearsightedness
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If an individual has Myopia, he/she cannot see ___ objects
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Distant
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If an individual had Hyperopia he/she cannot see ___ objects
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Close
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When the far point is too close it is called...
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Myopia/ Nearsightedness
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When the near point is too far away it is called?
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Farsightedness/ Hyperopia
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Presbyopia is also known as...
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Normal aging retreat of the near point
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Normal aging retreat of the near point?
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Presbyopia
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The near point is how far away?
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20 cm
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The far point is how far away?
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6 m
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What affect does luminance level have on visual acuity and contrast sensitivity?
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As luminance level increases, so does visual acuity and contrast sensitivity
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Does visual acuity ever change with age?
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Yes, visual acuity decreases with age
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Can visual acuity be improved by training?
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Yes, visual acuity can be improved by training people to control their focus
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What is the difference btwn visibility and contrast?
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Contrast is not affected by illumination, but visibility is.
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What are fast, jerky movements of the eyes called?
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Saccades
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What are stationary periods of eye motion called?
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Fixations
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What are reverse movements of the eye called?
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Regressions
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How is legibility different than visibility?
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Legibility is the attribute of characters that makes each one of them identifiable from the others, while visibility is the quality of the characters that make them visible from their surroundings.
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How is readability different from legibility?
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Readability refers to a group of informational content and how it is presented.
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When referring to topography, how large is one pt?
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.25 mm
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What is the most optimal font size proven by studies?
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11 pt
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What is the purpose of the term luminance?
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To state that lights of equal energy, but different wavelengths do not all appear to be equally bright.
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Why do lights of equal energy, but different wavelengths not appear equally bright? and what is this called?
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It is called Luminance.
Our visual system is not equally sensitive to all wavelengths of light, therefore different wavelengths may appear to be brighter than others. |
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Around what wavelength does brightness appear greatest to our visual system?
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Between 500 and 600 nm.
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Does light adaptation or dark adaptation take longer?
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Dark adaptation is longer. ( May take up to 40 minutes)
Light adaptation takes around 90 seconds for 50% of recovery |
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What does the Purkinje Shift describe?
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As illumination goes from bright to dim, some colors appear lighter and some darker.
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As illumination goes from bright to dim, the change in green is what?
What is this process called again? |
Green goes from dark to light.
Purkinje Shift |
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During the Purkinje Shift, you go from using ___ vision to ____ vision...
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Photopic
Scotopic |
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People with normal vision are also called?
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Trichromats
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Typical colorblindness is called?
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Dichromacy
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When Parallel lines appear to converge at far distances this monocular cue is known as?
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Linear Perspective
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Interposition, a monocular cue, is what?
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When distant objects are obscured by those far away
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When eyes are seperated to yield slightly different views, this binocular cue is also known as?
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Retinal Disparity
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What is autokinesis?
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When a static light is stared at in the dark, the light appears to move.
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When a static light is stared at in the dark, the light appears to move. This is known as...
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Autokinesis
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When the movement of a car next to you is mistaken as your car moving this is known as?
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Relative Motion
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Cloud formations may be confused with the horizon or ground. This real-life visual illumination is also known as...
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False Horizon
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Bodies that offer light as a source, and are not just reflecting light are known as...
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Incandescent bodies
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Bodies that reflect light as a source are considered...
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Luminescent bodies
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What is the difference between illuminance and luminance?
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Illuminance is the amount of light striking a surface
Luminance is the amount of light leaving a surface (generated or reflected from) |
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Define Lumen...
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Measure of light from an energy source
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Define Footcandle...
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One lumen / sq foot
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Define Lux
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One lumen/ sq meter
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Name ways to reduce glare from luminaries...
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* Select luminaries with low DGR
* Use shield, hoods, visors * Resort to indirect lighting |
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Name some problems with aging that affect vision...
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* Lens thickens and can cause farsightedness
* Lens thickens and becomes yellow, inhibiting blue light from passing through * Lens thickens and causes light to scatter |
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What is the fovea's purpose?
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For sharp, central vision
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