L1-L3

Question 1

Perceptual illusion

Answer 1

a difference between what is perceived and what is physically present in the world

Question 2

Optical illusion

Answer 2

a difference between what is in the retinal image and what is physically present in the world

Question 3

Sensation

Answer 3

the ability to detect a stimulus and turn that detection into a private experience

Question 4

Perception

Answer 4

the act of giving meaning/purpose to those detected sensations

Question 5

3 stages of the sensation process

Answer 5

physical stimulus, physiological response, sensory experience

Question 6

Examples of techniques for studying the physiological response from a physical stimulus

Answer 6

animal single-unit recording, human brain imaging (e.g. MEG, PET, fMRI, ERPs)

Question 7

Examples of techniques for studying the sensory experience from a physiological response

Answer 7

animal lesion studies, human clinical studies, human brain imaging

Question 8

What is Fechner’s contribution to psychology?

Answer 8

invented psychophysics and believed to be the true founder of experimental psychology

Question 9

Psychophysics

Answer 9

the science of quantifying the relationship between physical and psychological experiences

Question 10

Just noticeable difference (JND)

i.e. difference threshold

Answer 10

the smallest change in a stimulus or difference between stimuli that can be detected 50% of the time

bigger JND needed for heavier standard weights relative to comparison

Question 11

Absolute threshold

Answer 11

minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time

Question 12

Psychometric function

Answer 12

a graph of stimulus value (e.g. intensity) on the horizontal axis versus the subject’s responses (e.g. proportion of “yes”) on the vertical axis

ogive or typical S shape

Question 13

Weber’s law

Answer 13

the size of the JND or the difference threshold (△I) is a constant proportion (K) of the physical magnitude of the stimulus (I)

△I = KI

Question 14

Fechner’s law

Answer 14

a principle describing the relationship between stimulus magnitude and the resulting sensation magnitude (i.e. scaling)

S = KlogR

Question 15

What does Fechner’s law predict?

Answer 15

stimulus intensity increases more rapidly than sensation intensity (i.e. a larger change is needed to produce a JND in sensation as stimulus intensity increases)

Question 16

Magnitude estimation

Answer 16

easier method for psychophysical scaling, wherein a participant assigns a number to describe stimulus intensity

Question 17

What do magnitude estimation experiments show?

Answer 17

once detected, the sensory magnitude of a stimulus increases with its physical magnitude, within limits

Question 18

Steven’s power law

Answer 18

the magnitude of subjective sensation (i.e. perceived intensity) is proportional to stimulus magnitude raised to an exponent (or power)

S = aI^b

Question 19

2 possible reasons for the discrepancy between Fechner’s law and Steven’s law

Answer 19

assumption that all JNDs are perceptually equal (Fechner’s) is violated for some sensory modalities; magnitude estimation is more subjective than determining JNDs

Question 20

3 classical psychophysical methods

Answer 20

method of constant stimuli, method of limits, method of adjustment

Question 21

Discrimination

Answer 21

the ability to tell the difference between two stimuli or if a stimulus has changed

Question 22

Suprathreshold stimulus

Answer 22

above the absolute threshold so always detectable

Question 23

Method of constant stimuli

Answer 23

standard and comparison stimuli presented together; magnitude of comparison (above and below standard) varies randomly from trial to trial

Question 24

Formula for JND

Answer 24

(upper limit - lower limit)/2

Question 25

Method of limits

Answer 25

standard and comparison stimuli are presented together, and you alternate between descending and ascending series while varying the starting point in each

Question 26

Method of adjustment

Answer 26

observer adjusts the comparison stimulus until it matches the standard stimulus while the experimenter randomly varies the starting point

Question 27

Advantages of method of constant stimuli

Answer 27

accurate and repeatable threshold values

Question 28

Disadvantages of method of constant stimuli

Answer 28

time-consuming; not good for children or clinical patients; not good for tracking thresholds over time; lots of data collected far from threshold

Question 29

Advantages of method of limits

Answer 29

saves time and not necessary to trace out the entire psychometric function

Question 30

Disadvantages of method of limits

Answer 30

habituation error (making the same response repeatedly) and anticipation error (changing response after a fixed number of trials)

Question 31

How to reduce habituation and anticipation errors in the method of limits?

Answer 31

alternate the series (requires extra series) and vary the starting point in each (requires extra stimulus levels)

Question 32

Advantages of method of adjustment

Answer 32

quick and participants like it

Question 33

Disadvantages of method of adjustment

Answer 33

not very accurate or repeatable

Question 34

2 modern improvements to the classic psychophysical methods

Answer 34

staircase method and 2-alternative forced-choice paradigm

Question 35

Staircase method

Answer 35

increase (or decrease) intensity of stimulus in equal steps until it can (or can’t) be detected

Question 36

Absolute threshold in the staircase method

Answer 36

the average of the cross-over points at response reversals

Question 37

Adaptive function of the staircase method

Answer 37

stimuli intensity keeps hovering around the absolute threshold by adapting the test sequence to the participant’s responses

Question 38

Advantages of using the staircase method

Answer 38

efficient, most data collected around the threshold (adaptive!), can be used to track threshold changes over time

Question 39

How do you reduce habituation and anticipation errors in the staircase method?

Answer 39

use randomly interleaved descending (strongest to weakest stimulus intensity) and ascending staircases

Question 40

What is the difference between a yes/no paradigm and the 2-alternative forced-choice paradigm?

Answer 40

former is subjective and the participant has to report whether they can detect or discriminate a stimulus; latter is more objective and the participant must prove that they can detect or discriminate the stimulus ## Footnote e.g. Was the tone in the first or second interval? (detection) or in which interval are the 2 tones different? (discrimination)

Question 41

Advantages of using a 2-alternative forced-choice paradigm

Answer 41

accurate thresholds and reduces non-sensory differences among participants (bias or criterion differences)

Question 42

Cross-modality matching

Answer 42

scaling method in which the intensities of sensations that come from different sensory modalities are matched (e.g. brightness and loudness)

Question 43

How does the signal detection method provide a bias-free estimate of sensitivity?

Answer 43

the use of a 2-alternative forced-choice paradigm reduces perceiver bias/criterion because bias is measured directly

Question 44

2 factors affecting perceptual measurements in signal detection method

Answer 44

motivational state and sensory capacities of the perceiver

Question 45

Catch trials

Answer 45

trials in a signal detection experiment wherein the stimulus/signal is absent

Question 46

Sensitivity

Answer 46

the ease with which a perceiver can tell the difference between the presence and absence of a stimulus

Question 47

d'

Answer 47

the statistic that reflects a perceiver's sensitivity

Question 48

What happens to the response outcome as you reduce stimulus intensity in a signal detection experiment?

Answer 48

reducing stimulus intensity decreases sensitivity (d'), so you make less hits and more false alarms

Question 49

2 reasons why people make false alarms

Answer 49

endogenous noise and criterion (β)

Question 50

Endogenous noise (sensory)

Answer 50

spontaneous neural activity that affects the measurement of thresholds and sensitivity

Question 51

Criterion (β)

Answer 51

response bias within a perceiver that depends on expectations and motivation ## Footnote level above which sensation is attributed to the signal and not the noise

Question 52

How can you manipulate criterion in a signal detection experiment?

Answer 52

varying the stimulus probability or expectations

Question 53

What happens to the response outcome as you reduce stimulus probability

Answer 53

reducing stimulus probability increases criterion strictness or β (e.g. say "no" more so low hits and false alarms) but doesn't affect sensitivity (d')