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Sensation and Perception > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

Additive Color Mixing

A

Mixing that happens when lights of different wavelengths are perceived by the eye
- Red, Green, Blue

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2
Q

Subtractive Color Mixing

A

Physical process of color mixing that happens within the stimulus (paint)
- Red, Yellow, Blue

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3
Q

Visible Lights

A
  • wavelengths of light are either absorbed or reflected (what we see)
  • White reflects all colors of light
  • Black absorbs all colors of light
    Ex: Red/Blue absorbs, Green reflects
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4
Q

Sclera

A

White of the eye

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5
Q

Eye muscle

A

1 of 6 surrounding muscles to help rotate the eye in all directions

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6
Q

Iris

A

Colored area containing muscles that control the pupil

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7
Q

Pupil

A

Opening at the center of the iris that lets light in
- Light reflected from objects)

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8
Q

Lens

A

Transparent disk that focuses light rays for near or distant vision (20% of light is focused)

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9
Q

Cornea

A

Curved, transparent dome that bends incoming light (80% of light is focused)

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10
Q

Retina

A

Innermost layer of the eye, where incoming light is converted into nerve impulses
- 120 million rods
- 6 million cones

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11
Q

Fovea

A

Part of the retina where incoming light rays are most sharply focused
- Size of 12pt font “o”
- Contains only cones (50,000 or 1%)

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12
Q

Optic Nerve

A

Transmits impulses from the retina to the rest of the brain

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13
Q

Blind Spot

A

Place where the optic nerve leaves the eye (No receptors)

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14
Q

How to find your Blind Spots

A
  • Fills in the space where the image disappears
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15
Q

Macula

A

fovea and small area surrounding fovea

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16
Q

Macular Degeneration

A
  • age related
  • fovea is destroyed because the cones are breaking down
  • blurry on what you are trying to focus on
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17
Q

Retinitis Pigmentosa

A
  • genetic disease
  • attacks the rods (dark spots indicate damaged rods)
  • can lead to blindness
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18
Q

Focusing Light on Receptors

A
  • upside down and backwards
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19
Q

Accommodation

A
  • process occurs unconsciously
  • change in shape of the lens
  • muscles at front of the eye tighten/contract –> increases the curvature of the lens and gets THICKER
  • eye is constantly adjusting based on distances
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20
Q

Myopia

A

corneas too steep or eyes too long
(Nearsightedness)
- visual focus at the front of retina

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21
Q

Hyperopia

A

corneas too flat or eyes too short
(Farsightedness)
- visual is behind retina

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22
Q

How do we get it corrected?

A
  • brain converts raw date and makes sense of it
  • occipital lobe
  • doesn’t rotate image back in place
  • takes account location cues based on head orientation
  • newborns may see inverted
  • Corpus callosum –> linking left and right hemispheres
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23
Q

Pathway to the brain (Left)

A
  1. left visual signal
  2. right side of retina along the optic nerve
  3. right thalamus
  4. right visual cortex (occipital lobe)
24
Q

Pathway to the brain (Right)

A
  1. right visual field
  2. left sides of retinas along optic nerve
  3. left thalamus
  4. left visual field (occipital lobe)
25
Q

Visual Transduction

A
  • light into electricity
  • 2 visual pigment molecules (opsin and retinal)
  • occurs when retinal absorbs light
26
Q

Opsin

A

a large protein

27
Q

Retinal

A

light sensitive molecule
- changes shape from bent to straight “isomerization”

28
Q

Visual Pigment Bleaching

A
  • original color is dark
  • when bleached it is not useful for vision
  • ## retinal needs to become bent and reattach the opsin for transduction (visual pigment regeneration)
29
Q

Dark Adaptation

A
  • cones adapt in 3-4 mins (sharp/focus/color)
  • rods adapt in 20-30 mins (low light–> shape & form)
30
Q

Color Perception: Trichromatic Color Theory

A
  • 3 kinds of cones
  • each sensitive to various wavelengths
  • Blue (short), Green (medium), Red (long)
    – Helps understand color blindness
31
Q

Trichromats

A

Human, monkey, apes

32
Q

Dichromats

A

Dogs, most humans that have color blindness

33
Q

Monochromats

A

rare, no color vision, only 1 type of cone

34
Q

Opponent Process Theory

A
  • neurons have an excitatory and inhibitory response to various wavelengths
  • Opponents:
    — Red/Green, Yellow/Blue, White/Black
35
Q

Afterimage

A
  • Eyes adapt to colors when the specific cones for those colors receive the light and fire
  • if the color isn’t there, the neurons will not fire
  • Absolute refractory
  • Result is perception of opposite color
36
Q

Absolute Refractory

A

when you remove stimulus you have fatigued cells
- ones that aren’t overworked will fire, fatigued won’t fire

37
Q

3 Parts to Visual Pathway

A
38
Q

Parts of a Neuron

A
  • nerve fiber
  • synapse
  • cell body
  • dendrite
  • axon/nerve fiber
  • mylin
39
Q

Action Potentials

A
  • electrical signals that take place in a neuron
    (know how to label an action potential pathway)
40
Q

Know the cellular level of a action potential!

A

:)

41
Q

Features of Action Potentials

A
  • Propagated Response
  • Refractory Period
  • Spontaneous Activity
42
Q

Propagated Response

A

When triggered, continues down axon at the same strength

43
Q

Refractory period

A

~ 1 ms recovery time
- when one nerve impulse occurs and another can be generated

44
Q

Spontaneous Activity

A

baseline firing
- AP occur in absence of stimuli from environment

45
Q

How to Change rate of firing

A
  • Changing stimulus intensity changes, NOT size of AP
  • max 500-800 impulses per sec
46
Q

Responses at Receptor Sites

A

Excitatory and Inhibitory

47
Q

Excitatory response

A
  • closer to positive
  • increase chance of AP
  • Depolarization (more positively charged)
48
Q

Inhibitory Response

A
  • closer to negative
  • decreases chance of AP
  • Hyperpolarization (becoming negatively charged)
49
Q

A Response Depends on…

A
  1. type of neurotransmitter released
  2. properties of the receptor site (receiving neuron)
50
Q

Glutamate

A
  • Primary Excitatory NT
  • Receptor Sites: NMDA, AMPA, Kainate
  • Na+ ions flow into cell
  • Depolarization
51
Q

GABA

A
  • Primary Inhibitory NT
  • GABAa: Ion channel opens
    – Cl- ions flow into cell
  • GABAb: Protein –> Ion channel opens
    – K+ ions leave cell
  • Hyperpolarization
52
Q

Each Eye Contains

A
  • 126 million receptors (120 rods, 6 cones)
  • 1 million ganglion cells (per eye)
  • ratio for rods to ganglion (120:1)
  • ratio for cones to ganglion (6:1)
  • cones in fovea are 1:1 ratio
53
Q

Convergence

A
  • when a number of neurons synapse onto a single neuron
  • signals form rods converge MORE and cones converge LESS
    resulting in rods being more sensitive to light and cones having better detailed vision (acuity)
54
Q

SHORT ANSWER Question

A
55
Q

Convergence Summary

A
  • High convergence: high sensitivity and low acuity (ROD)
  • Low convergence: low sensitivity and high acuity (CONE)
56
Q

Testing Visual Acuity

A
  • reading symbols on an eye chart
  • babies need specialized methods
    — Preferential Looking (PL) Technique
    — Visual Evoked Potential (VEP)

Sensation and Perception (4 decks)

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