Chapter 6: More Vision

Question 1

Law of Specific Nerve Energies

Answer 1

Johannes Muller; regardless of the type of stimulus, activity in the nerve always leads to the same psychological experience.

Question 2

Photons

Answer 2

packets of energy with oscillating electromagnetic fields that travel through space at 3.0e8 m/s. Brightness of a light source depends on how many photons it emits

Question 3

Wavelength

Answer 3

based on the frequency of electromagnetic oscillation taking into account the speed of light. Color of a light source depends on wavelengths of the photons

Question 4

Electromagnetic Spectrum

Answer 4

light makes up small portion; x-rays to radio waves

Question 5

Choroid Coat

Answer 5

found behind retina; heavily pigmented to absorb scatteredlight; provides oxygen and nutrients for parts of retina; maintains photoreceptors

Question 6

Cornea

Answer 6

main refractive surface of the eye; bends the light; fluid filled

Question 7

Lens

Answer 7

Does bend light; provides visual accommodation; siscilary muscles contract and pull the ligament and make lens thinner, relax to make it more round

Question 8

Visual accommodation

Answer 8

provides fine focus by changing thickeness

Question 9

Presbyopia

Answer 9

condition in which the lens lose resiliency with age

Question 10

Iris

Answer 10

radial muscle tissue which constricts or expands the size of the pupil. Determines eye color

Question 11

Humors

Answer 11

provide structural and functional support for the eye

Question 12

Aqueous Humor (fluid)

Answer 12

in anterior chamber. Behind the cornea, in front of the lens

Question 13

Vitreous humor

Answer 13

in posterior chamber. located behind the lens; helps eye maintain shape (thicker)

Question 14

Retina

Answer 14

contains the visual photoreceptors and neurons that process and transmit visual information to the brain

Question 15

Fovea

Answer 15

indentation in the retina, contains only cones (point of central focus)

Question 16

Macula

Answer 16

has a lot of cones, surrounds the fovea

Question 17

Photoreceptors

Answer 17

hyperpolarize in response to light (depolarize in response to dark), and synapse with horizontal cells and bipolar cells (RODS AND CONES)

Question 18

Horizontal cells

Answer 18

have large dendritic trees that make inhibitory contaact with many nearby photoreceptors; responsible for phenomena of lateral inhibition (no action potentials)

Question 19

Bipolar Cells

Answer 19

each stimulated by a group of surrounding photoreceptors forming a receptive field. synapse with ganglion cells (no action potentials)

Question 20

ganglion cells

Answer 20

each stimulated by a group of surrounding bipolar cells forming a receptive field; convergence of input through the visual pathway; axons form optic nerve

Question 21

amacrine cells

Answer 21

modulate the output of bipolar cells

Question 22

Trichromatic Theory of Color Vision

Answer 22

color vision is based on ratio of responses from 3 different types of cones that have peak absorption of light at different wavelengths

Question 23

Opponent Process Theory of Color Vision

Answer 23

the way the information is organized in the visual system appears to be based on two opponent processes: Red vs. Green; Yellow vs. Blue

Question 24

Psychological evidence

Answer 24

no reddish-green or blueish-yellow color perceptions

Question 25

Electrophysiological evidence

Answer 25

Some bipolar cells, ganglion cells, LGN cells, and cortical cells have center-surround receptive fields that are organized in opponent process way

Question 26

Retinex THeory

Answer 26

suggests the cortex compares information from various parts of the retina to determine the brightness and color for each area. Better explains color constancy

Question 27

magnocellular pathway

Answer 27

named after the large cell bodies of the retinal ganglion cells and LGN cells of the pathway

Question 28

Parvocellular pathway

Answer 28

named after the small cel bodies of the retinal ganglion cells and LGN cells of the pathway

Question 29

Parvocellular ganglion cells

Answer 29

have small cell bodies, small receptive fields, are dense and near fovea

Question 30

Magnocellular ganglion cells

Answer 30

large cell bodies, large receptive field, and are uniformly distributed in the retina

Question 31

koniocellular ganglion cells

Answer 31

small cell bodies, mixed receptive field size, and are distributed uniformly throughout retina

Question 32

simple cells

Answer 32

small receptive fields, bar or edge shaped, excitatory and inhibitory zones, spots of light can produce weak excitatory or inhibitory responses

Question 33

complex cells

Answer 33

larger receptive fields, no clear cut inhibitory zones, spots of light are relatively ineffective, responds to bars of light of a specific orientation anywhere in receptive field

Question 34

occular dominance

Answer 34

cells in particular column respond best to input from left eye and from right eye