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Theory of the moon illusion that says objects appear smaller when the head is tilted up than when held parallel to the ground |
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The earth's terrain causes the moon to look further away, and thus bigger when at the horizon. |
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Two lights blinking on & off will, at the proper frequency, appear to be one moving light. |
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if a stationary light in otherwise complete darkness is fixated upon, it will eventually give the appearance of moving erratically. |
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After adapting to motion in a particular direction, the visual world appears to move in the opposite direction |
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disorder in which lines of one orientation are in focus, but lines of other orientations are not |
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inability to focus on objects in old age |
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the nearest point at which someone can bring objects into focus |
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the furthest point at which someone can bring objects into focus |
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a period of neural plasticity when particular environmental stimulation must be available for normal brain development |
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pressure changes in a medium which are capable of being detected by auditory organs |
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the set of all positions that could produce a particular time & intensity difference between the two ears. |
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What two factors determine an object's perceived size? |
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Definition
1. The retinal size of the stimulus
2. one's perceived distance to the stimulus |
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What did Kaufman and Rock find was the best predictor of the magnitude of the moon illusion? |
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Definition
The perceived distance to the horizon |
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Definition
certain kinds of cells on the retina and some distance apart from each other, will, when stimulated at a particular delay interval, excite a complex cell.
The phi effect simulates this pattern of stimulation. |
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cause of the autokinetic effect |
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Definition
when fixating the light, eye muscles become tired.
To compensate for this, the brain must send abnormally strong signals to muscles in the eye to continue fixation.
These signals are the same as would be required to track a moving object, so the brain assumes the light is moving. |
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what sort of brain damage can lead to motion blindness |
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Definition
Damage to area MT in the visual cortex can cause Akinetopsia (motion blindness) |
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Name the four kinds of eye care specialists and their specialties: |
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Definition
1. Opthalmologist: MD who specializes in diagnosing & treating disorders of the visual system
2. Optometrist: Measures the refractive state of the eye & tests for certain diseases. They also prescribe lenses.
3. Optician: makes optical instruments & lenses
4. Orthopist: works with people who have problems with binocular co-ordination |
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Anatomical problem that lead to astigmatism: |
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Definition
Lack of a spherical cornea |
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anatomical problems that lead to presbyopia: |
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Definition
hardening of the lens & weakening of the ciliary muscles |
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What kind of lens is required to correct myopia? |
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Definition
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What kind of lens is required to correct hypermetropia? |
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What does acuity testing measure? (visual) |
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Definition
The ability to detect high spatial frequency information (small things). |
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In the lines of the eyechart, each line is expressed as a fraction. What do the numerators and denominators of these fractions mean? |
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Definition
# in numerator: Distance (in feet) at which the test was (should be) conducted.
# in denominator: Distance (in Ft) at which the critical feature (gap in the letter 'C') of the test symbol covers one minute of visual angle |
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Term
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Definition
PRK- (Photorefractive Keratectomy) The epithelial tissue of the cornea is removed, and then a laser beam reshapes the cornea.
LASIK: (Laser In Situ Keratomtomilensis) 25% of the cornea is cut into a flap & folded back. Then, a laser reshapes the cornea.
Intacts: Pieces of plastic are placed in the cornea to change its shape. |
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Cause (3) & treatments (2) of Cataracts: |
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Definition
Causes: Congenital defect, acquired by injury/disease, old age
treatments: artificial implants, or lens removal & cataract spectacles |
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cause & treatment of Retinitis Pigmentosa |
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Definition
Caused by an inherited disorder of the photoreceptors, whereby rods degenerate starting in the periphery, and eventually spreading to all rods.
Treatment: none at present |
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cause & treatment of Diabetic retinopathy: |
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Definition
Cause: Leaking walls of the blood vessels serving the retina.
Leads to detached retina, blood in the vitreous humor & new blood vessel growth across the retina.
Treatment: Laser photocoagulation |
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cause & treatment of detached retina: |
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Definition
Cause: Photoreceptors become detached from the pigment epithelium
Treatment: purposeful injury of the eye to create scar tissue that locks the retina into place |
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cause & treatments (2) of Glaucoma |
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Definition
cause: ganglion cell death caused by increased pressure on the blood vessels serving the retina, which is in turn caused by problems draining the aqueous humor.
Treatment: Drugs that either remove blockage of the aqueous humor drains or decrease production of the humor.
Surgery if the drugs fail. |
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Term
Hubel & Weisel kitten visual development experiment:
A) how did it effect the eye itself
B)" The LGN Cells
C)" cells in V1 |
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Definition
A)Eye completely normal
B) Fewer LGN cells devoted to the eye, but remaining cells responded normally
C) V1 Cells abnormally preferred the open eye (only 15% responded to the closed eye at all) |
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Two reasons why environmental stimulation might be necessary for normal perceptual development: |
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Definition
1. For binocular cells, neural plasticity may allow for adjustments due to the changing distance between the eyes.
2. It may be wise for the body to kill unused cells in the brain as a survival mechanism |
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disadvantage and three advantages of a compound eye: |
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Definition
Dis: Very poor acuity
Adv: 1.Equal visibility across the visual field
2.Always in focus
3. Higher Flicker Fusion Frequency (eye framerate) |
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Flicker Fusion Frequency for Humans:
For insects? |
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Definition
Humans: 10-24 Hz
Insects: ~300Hz |
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Two physiological reasons why birds have higher visual acuity than humans: |
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Definition
- More densely packed photoreceptors
- Very high ratio of Ganglia to Photoreceptors compared to humans |
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Three ways different nocturnal animals have developed to navigate the dark: |
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Definition
1. By having very sensitive eyes
2. By having organs that read Infrared wavelengths
3. By using echolocation |
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What is the frequency range bats use for echolocation |
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Definition
30,000 to well over 100,000 Hz |
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how do bats prevent damage to their eardrums when using echolocation? |
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Definition
They suppress the vibration of the eardrum prior to sending the signal |
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which visual abilities are best in humans, relative to other animals? |
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Definition
1. Best form vision
2. Best stereovision |
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Illusion causes:
1. Poggendorf 2. Wundt-Hering 3. Ponzo 4. Ames window 5. Wagon Wheel |
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Definition
1. Poggendorf: Combination of blur by the optic media, retinal lateral inhibition , & processing strategies
2. Wundt-Hering: Seems to be a large number of Poggendorff illusions
3. Ponzo: Linear perspective & texture gradients make the top bar look further away, & thus bigger
4.Ames Window: The retinal image is consistent with both a) a trapezoidal window rotating 360, b) a rectangular window flipping directions every 180.
Since we're used to seeing rectangular windows, the brain prefers that interpretation.
5.Wagon Wheel: The framerate of the movie is out of sync with the wheel, and the image on the film appears to be more consistent with the wheel moving backwards. |
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Units for measuring sound frequency?
Amplitude? |
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Frequency (Hz) The number of times a wave repeats itself.
Amplitude (dB): Difference between the atmospheric pressure & the maximum pressure exerted by the sound wave |
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Term
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Definition
dB = P / (20 Log P-nought)
Where:
P = Amplitude of the wave being measured
P-nought = reference pressure
dB = Decibels |
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what are the psychological correlates for frequency and amplitude? |
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Definition
Frequency = Pitch
Amplitude = Loudness |
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To what frequency range is the human auditory system able to respond? |
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Definition
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Structures of the outer ear (3), and functions |
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Definition
Pinna - Amplifies and localizes high frequency sound
Meatus - function not required for exam
Tympanic Membrane - vibrates in response to pressure changes in the atmosphere |
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Two functions of the Ossicles: |
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Definition
1. Amplify tympanic vibrations
2. Protect the inner ear from loud sounds |
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Term
Functions of the Oval Window, Basilar membrane, and the Hair cells |
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Definition
oval window: transmit vibrations to the fluid in the cochlea
Basilar membrane: vibrates deferentially, depending on the frequency of the stimulus
hair cells-when the region beneath a given hair cell vibrates, the cell bends & releases neurotransmitters that stimulate corresponding cells in the auditory nerve. |
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Term
What happens if we bilaterally remove the auditory cortex (4 things)? |
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Definition
In cats, it resulted in inability to:
1. Discriminate different tunes (the word TUNES is important)
2. Discriminate changes in the duration of TONES (not tunes)
3. Localize sound
4. Determine which ear was stimulated |
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Explain Von Beckesey's Place Theory of frequency perception |
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Definition
Different locations on the basiliar membrane vibrate in responce to different frequencies; the hair cells being stimulated with the greatest amount of vibration indicate the frequency. |
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Evidence (2) of Von Beckesey's Place Theory |
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Definition
1. A strong relationship exists betweeen the fequency of the sound & the place where the basilar membrane vibrates most during that sound.
2. Selective deafness experiments show that damage is restricted to certain hair cells. |
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Explain Rutherford's Frequency Theory of frequency perception |
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Definition
The basilar membrane vibrates at the same frequency as the stimulus.
Every time the basilar membrane vibrates, it causes an action potential in the auditory nerve.
So, then, the firing rate of the auditory nerve should indicate the frequency of the stimulus. |
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What happens when two separate tones are played simultaneously, and:
1) The tones are separated by 1-15Hz
2) The tones are separated by more than 15Hz, but less than the critical bandwidth
3) the tones are separated by more than the critical bandwidth |
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Definition
1) A tone midway between the presented tones is perceived, which oscillates in loudness at the same frequency as the difference between the tones (the "beats" phenomenon)
2)A single tone, midway in frequency between the presented tones that sounds "rough"
3) two separate tones |
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List two monaural cues for localizing sounds: |
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Definition
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Two binaural cues for localizing sounds: |
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Inter-aural time difference (different ear time delay)
Inter-aural intensity difference (the head's sound shadow differential between the ears) |
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When is inter-aural intensity difference most effective for localizing sounds? |
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Definition
High frequency sound (cause higher frequencies are more affected by obstructions) |
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How can we overcome the Cone of Confusion? |
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Definition
Moving our heads to triangulate the sound origin. |
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