Quiz 5 Review

Question 1

Sensation

Answer 1

the detection of physical energy by sense organs (by cells in eye, nose, ear, skin, and tongue)

Question 2

Transduction

Answer 2

Conversion of stimulus of electrical signal

Question 3

Perception

Answer 3

the brain’s interpretation of raw sensory input

Question 4

What do sensation and perception do?

Answer 4

Sensation gathers info from the external world, and perception helps us make sense of the info

Question 5

Absolute threshold

Answer 5

the smallest amount of stimulus we can detect at least 50% of the time

Question 6

Just noticeable difference (JND)

Answer 6

the smallest change we can detect in stimulus strength

Question 7

Sensory adaption

Answer 7

a decrease in the noticeability of a stimulus over time
- happens at the sensory receptor level (e.g. candle scent)

Question 8

True or False: our perceptual experience is a direct translation of sensory input

Answer 8

• False
• We use more than just sensory input to make sense of the world
• perception = sensory input+past perceptions+context+guesses
• we need this, partly, bc the sensory input isn’t always clear or complete

Question 9

Signal-to-noise ratio

Answer 9

sometimes the stimulus is unclear so our brain makes its best guess

Question 10

Perceptual constancy

Answer 10

the process by which we perceive stimuli consistently across varying conditions

Question 11

Shape constancy

Answer 11

where an object is perceived as having the same shape when viewed at different angles (e.g. door)

Question 12

Color constancy

Answer 12

our ability to perceive colors as relatively constant over varying illuminations (light sources)

Question 13

Visible light

Answer 13

wavelength: 400nm - 700 nm of light

Question 14

Pupil

Answer 14

a hole that allows light into the eye

Question 15

Iris

Answer 15

colored part, muscle that controls pupil

Question 16

Cornea

Answer 16

outside covering that helps protect and focus light

Question 17

lens

Answer 17

a disc that focuses light on the back of the eye
- lens inverts the image as it focuses it

Question 18

Retina

Answer 18

membrane on the back of the eye containing sensory receptors

Question 19

Optic nerve

Answer 19

transmits visual signals to the rest of the brain

Question 20

Fovea

Answer 20

area of the retina where light is focused

Question 21

Why care about fovea?

Answer 21

• light focused on the fovea controls how well you see

Question 22

Myopia

Answer 22

nearsighted: light focuses too soon

Question 23

Hyperopia

Answer 23

farsighted: light focuses too late

Question 24

Visual System

Answer 24

• the eye
• photoreceptors
• color vision

Question 25

Visual Perception

Answer 25

top-down/ bottom-up processing, feature integration theory

Question 26

Photorecpetors

Answer 26

• located in the retina
• visual sensory receptors (two types: cones, rods)
• rods and cones connect to ganglion cells

Question 27

Cones

Answer 27

• sense bright light and color, work best in bright light
• cones are connected at fovea (very high acuity)

Question 28

Rods

Answer 28

• sense dim light, become oversaturated in bright light
• rods are concentrated in the periphery (low acuity, might improve night vision, need time to recover if exposed to too much light, dark adaption takes approx 30 minutes)

Question 29

Ganglion cells

Answer 29

• carry visual info from eye to brain
• form optic nerve
• blind spot: filled in through brain’s perception/ guesses

Question 30

Color vision

Answer 30

• light (sunlight) has all wavelengths in it
• some wavelengths are absorbed by surfaces, others are reflected

Question 31

Reflected Light

Answer 31

–> color
- subtractive vs. additive color mixing

Question 32

Subtractive color mixing

Answer 32

mixing pigment absorbs more light (looks darker) –> color

Question 33

Additive color mixing

Answer 33

mixing colored lights gives off more light (gets brighter) –> light

Question 34

Trichromatic theory of color vision

Answer 34

• idea that color vision is based on three primary colors: blue, green, red
• 3 types of cones: tuned to respond to blue, green, red
• patterns of activity between different cones types allows us to see all possible colors

Question 35

Color blindness

Answer 35

• occurs when one cone is missing
• called dichromatic vision
• 5% of men and 0.25 % of women are color blind

Question 36

Opponent process theory of color vision

Answer 36

• we perceive things in terms of opponent color pairs
• ganglion cells pool incoming info from cones
  (send one signal about the color to the brain)
• explains afterimages
  (cones get oversaturated, we see opposite color)