Psychophysics

Question 1

psychophysics

Answer 1

sensory psychology that quantifies the relationship between “stimulus magnitude” and “responses”

Question 2

psychometrics

Answer 2

develops a scale or function which describes a person’s performance

Question 3

nominal data

Answer 3

NAMED variable, no quantitative relation

Question 4

ordinal data

Answer 4

Increasing number corresponds to a monotonic change in parameters - ORDERED Categories (ranking, order, or scaling)

Question 5

Efron scale

Answer 5

degree of conjunctival redness

Question 6

interval

Answer 6

difference between any two adjacent numbers is equal

Question 7

ratio

Answer 7

proportion of numerical measurement

Question 8

threshold measurement

Answer 8

minimum intensity of stimulus required for an individual to just detect

Question 9

absolute threshold

Answer 9

the presence of a stimulus

Question 10

relative threshold

Answer 10

the difference between two stimuli

Question 11

chance of seeing a stimulus at threshold

Answer 11

75 percent

Question 12

chance of seeing a stimulus at infrathreshold

Answer 12

50 percent

Question 13

intensity discrimination

Answer 13

subjects match multiple brightness or until just different from stimuli

Question 14

standard of deviation of intensity discrimination

Answer 14

just noticeable difference

Question 15

method of limits

Answer 15

vary stimulus magnitudes in fixed small steps until response changes

Question 16

descending limits

Answer 16

start above threshold - First no or last yes

ex: Snellen chart

Question 17

ascending limits

Answer 17

start below threshold - first yes or last no

Question 18

advantage(s) of method of limits

Answer 18

quick procedure

Question 19

disadvantage(s) of method of limits

Answer 19

criterion; error of expectation; error of habituation

Question 20

criterion

Answer 20

when subject decides a stimulus is present or absent (bias on on practicioner/patient)

Question 21

constant stimuli

Answer 21

randomly presents stimulus at various magnitudes

Question 22

advantage(s) of constant stimuli

Answer 22

no error of habituation or expectation

Question 23

disadvantage(s) of constant stimuli

Answer 23

criterion; long and boring

Question 24

method of adjustment

Answer 24

subject tracks or brackets between seeing and not seeing

Question 25

advantage(s) of adjustment method

Answer 25

quick and offers some randomization

Question 26

disadvantage(s) of adjustment method

Answer 26

criterion; apparatus artifacts (physical errors due to apparatus)

Question 27

adaptive staircase

Answer 27

change stimulus magnitude by a given ratio (“steps”) depending on previous responses

Question 28

advantage(s) of adjustment method

Answer 28

criterion-free

Question 29

classic techniques

Answer 29

based on threshold concept - all have problem of criterion

Question 30

modern techniques

Answer 30

criterion free (not biased free)

Question 31

forced choice

Answer 31

formulated questions so the subjects response is NOT DIRECTLY related to stimulus magnitude AND subject must always respond with one of the permissible answers

Question 32

Landolt C

Answer 32

Forced choice where the C is open

Question 33

Threshold percent correct

Answer 33

(100% + guess rate)/2

Question 34

Guess Rate

Answer 34

1/#of choices in %

Question 35

4 alternative-spatial forced choice

Answer 35

measure thresholds (brightness) to spots of light using 4 alternative-spatial forced choice “which quadrant”

Question 36

threshold determined by forced choice vs classical methods

Answer 36

forced choice is lower threshold than classical methods