Sensation and Perception

Question 1

Sensation definition

Answer 1

Process by which sensory receptors and nervous system receive and represent stimuli

Question 2

Perception definition

Answer 2

Process of organizing and interpreting sensory information

Question 3

Bottom-up processing

Answer 3

1. Data-driven
2. Begins with incoming sensory information and continues to perception

Question 4

Top-down processing

Answer 4

1. Concept-driven
2. Using pre-existing interpretation to interpret incoming sensory information

Question 5

Vision

Answer 5

Light waves absorbed by photoreceptors in retina

Question 6

Two types of photoreceptors

Answer 6

1. Cones - bright lights, visual acuity, colors
2. Rods - dim lights, peripheral vision

Question 7

Visual acuity

Answer 7

Sharpness and precise detail

Question 8

Two main theories of color vision

Answer 8

1. Trichromatic theory
2. Opponent process theory

Question 9

Trichromatic theory

Answer 9

1. Retina contains red, blue, green cones
2. Related to initial processing in retina

Question 10

Opponent process theory

Answer 10

1. Red/green, blue/yellow, white/black cells
2. Related to processing beyond retina
3. Explains afterimages, blue/yellow colorblindness

Question 11

Color Blindness

Answer 11

1. Red/green most common - usually due to genetics but can be due to disease/injury
2. Blue/yellow - due to genetics

Question 12

Red/green color blindness (genetic mutation)

Answer 12

1. Recessive gene on X chromosome
2. More common in males (only have one X and only need one gene) than females (have two X and need gene on both)

Question 13

Blue/yellow color blindness (genetic mutation)

Answer 13

1. Autosomal (non-sex) dominant gene
2. Affects males and females equally

Question 14

Depth perception

Answer 14

Depends on binocular and monocular cues

Question 15

Binocular cues

Answer 15

1. Use both eyes
2. Depth perception of close objects
3. Retinal disparity and convergence

Question 16

Monocular cues

Answer 16

1. Use one eye
2. Depth perception of far objects
3. Size, overlap/position, linear perspective, texture, motion parallax

Question 17

Retinal disparity

Answer 17

1. Two eyes seeing objects from two different views
2. Closer object = greater disparity

Question 18

Convergence

Answer 18

Tendency of eyes to turn inward when an object is closer and vice versa

Question 19

Gate control theory

Answer 19

1. Pain perception
2. Differentiates two types of nerve fibers in spinal cord
3. “Gate” opens for pain signals (small unmyelinated) but closes for other sensory signals (large myelinated)

Question 20

Two types of nerve fibers in spinal cord (gate control theory)

Answer 20

1. Small unmyelinated - transmit most pain signals to brain
2. Large myelinated - transmit other sensory signals to brain

Question 21

Synesthesia

Answer 21

1. Sensations in one modality spontaneously trigger sensations in another modality
2. Most common = grapheme-color
3. May be genetic, increased cross-activation and cross-connectivity in brain’s sensory areas

Question 22

Grapheme-color synesthesia

Answer 22

Letters and numbers associated with colors

Question 23

Psychophysics

Answer 23

Study of relationship between magnitude of physical stimuli and psychological sensations

Question 24

Four psychophysics theories

Answer 24

1. Weber’s Law
2. Fechner’s Law
3. Stevens’s Power Law
4. Signal Detection Theory

Question 25

Weber’s Law

Answer 25

1. Just noticeable difference (JND) is a constant proportion regardless of object intensity
2. Only applies to some stimuli and mid-range intensities
3. Weight proportion = 2%

Question 26

Fechner’s Law (Fechner-Weber Law)

Answer 26

1. Logarithmic relationship (JND grows to increasingly greater degree with each increment in intensity)
2. Only applies to some stimuli and better than Weber’s for extreme intensities

Question 27

Stevens’s Power Law

Answer 27

1. Exponential relationship, with differing exponents based on stimuli
2. More accurate than Weber’s and Fechner’s laws
3. Developed from research on method of magnitude estimation

Question 28

Method of magnitude estimation

Answer 28

1. Participants assigned numbers to stimuli based on sensations elicited
2. Relationship between physical stimuli and sensation differs for different stimuli

Question 29

Signal Detection Theory

Answer 29

1. Perception (and accuracy) of a stimulus comes from both sensory and decision-making processes
2. Decision-making always uncertain due to background noise (other neural activity, fatigue, distractions)
3. Decision-making affected by sensitivity and decision criterion

Question 30

Sensitivity

Answer 30

Perceiver’s ability to differentiate between stimulus and background noise

Question 31

Decision criterion (decision bias, response bias)

Answer 31

Perceiver’s willingness or tendency to say a stimulus is present in ambiguous situations

Question 32

Signal Detection Theory research

Answer 32

1. Participants presented with weak or absent stimulus in a noisy background and then asked whether they detect signal or not
2. d-prime = estimate of sensitivity
3. ROC curve = how often hits and false alarms may occur for different levels of sensitivity, impact of changes in decision criterion

Question 33

Four possible outcomes in Signal Detection Theory experiments

Answer 33

1. Hit = says present (correct)
2. False alarm = says present (incorrect)
3. Miss = says not present (incorrect)
4. Correct rejection = says not present (correct)