Psychophysical Methods

Question 1

what is the independent variable in psychophysics

Answer 1

controlling/changing the physical stimuli

best to change randomly

Question 2

what is the dependent variable in psychophysics

Answer 2

measuring the perceptual/behavioral response

Question 3

the minimum value of a stimulus required to elicit a perceptual response or an altered perceptual response

Answer 3

threshold

Question 4

the lowest level of a stimulus for which a response is elicited (under ideal conditions)

Answer 4

absolute threshold

Question 5

the minimum difference in stimulus levels between two stimuli that can be detected

Answer 5

difference/ increment threshold

Question 6

the description of the stimulus in terms of luminance and spatial (or temporal) extent is called

Answer 6

luminance profile

Question 7

luminance profile x-axis

Answer 7

spatial extent

-in visual angle (degree) or linear angle (mm)

Question 8

luminance profile y-axis

Answer 8

luminance

-in cd/m^2

Question 9

(-) target / (+) polarity are when

Answer 9

target is darker than the background (like standard VA chart)

Question 10

original threshold theory / Fechner stated that

Answer 10

• threshold is all or non

- static (single) threshold

Question 11

classical theory of threshold stated that

Answer 11

• threshold is a sigmoid (S-shaped) curve

- threshold varies

Question 12

modern theory of threshold states that

Answer 12

• there is no threshold

- signal detection theory

Question 13

4 reasons why threshold varies

Answer 13

1. stimulus
2. neural activity
3. attention
4. psychological bias

Question 14

typically, the best most accurate method

Answer 14

method of constant stimuli

Question 15

what is the only method that gives the sigmoid (S-shape)?

Answer 15

method of constant stimuli

Question 16

pros and cons of method of constant stimuli

Answer 16

pros: very accurate, addresses attention issue of variability
cons: very slow and inefficient, does not get rid of bias

Question 17

presenting each stimulus level in increasing or decreases order is called

Answer 17

method of limits

Question 18

disadvantages of method of limits

Answer 18

patient bias/attention

• bases current judgement on previous responses
• anticipates transition point

Question 19

descending limits: we think it is ___ than it actually is

Answer 19

lower

Question 20

ascending limits: we think its ___ than it actually is

Answer 20

higher

Question 21

simplest method but usually the worst

Answer 21

method of adjustment

Question 22

2nd fastest method

Answer 22

staircase

Question 23

best method in the table is

Answer 23

staircase

Question 24

what method requires a lot of computation

Answer 24

signal detection theory

Question 25

what has magnitude but no obvious scale or units

Answer 25

sensations

Question 26

how can you measure sensations?

Answer 26

• ratio scaling (ratio production or ratio estimation)

- magnitude scaling (magnitude production or magnitude estimation)