3: Psychophysics

Question 1

sensation

Answer 1

simple conscious experience associated with a stimulus

Question 2

perception

Answer 2

conscious experience of objects/object relations

Question 3

psychophysics

Answer 3

quantitative investigation of relationship between physical stimuli and sensations/perceptions produced

Question 4

psychophysical problems

Answer 4

detection (is there)
identification (what)
discrimination (different)
scaling (how much)

Question 5

absolute threshold

Answer 5

min. amount of stimulus energy necessary for detection (50% of the time)

Question 6

fixed/constant set of stimuli

Answer 6

chosen beforehand

Question 7

psychometric function

Answer 7

relates an observer’s performance to an independent variable

stimulus intensity vs. perceived % of time

Question 8

noise

Answer 8

all other stimuli in environment

Question 9

payoff matrix

Answer 9

how the responses are rewarded

C, N, L

Question 10

signal detection theory

Answer 10

quantifies response of observer to the presentation of a signal in the presence of noise

Question 11

sensitivity d’

Answer 11

a value that defines the ease of an observation of the difference between presence/absence of a stimuli or difference between two

Question 12

criterion

Answer 12

internal threshold (set by observer) 
(above = yes, below = no)
low = alert for every, no misses but many false alarms
high = alert for only, no false alarm but many misses

Question 13

ROC curve

Answer 13

receiver operating characteristic curve

plot of the hit rate as a function of false-alarm rate

Question 14

difference threshold

Answer 14

DL/DT/just noticeable difference (JND, delta S)

smallest detectable diff between 2 stimuli

Question 15

point of subjective equality

Answer 15

.

Question 16

weber’s law

Answer 16

weber fraction is the same for any intensity of standard stimulus
deltaS/S = K
deltaS = JND (diff thresh)
S = standard stimulus
K = weber fraction/constant

Question 17

scale

Answer 17

nominal, ordinal, interval, ratio

rule in which we assign numbers to objects/events

Question 18

magnitude estimation procedure

Answer 18

standard stimulus
assign value to standard stim.
present diff intensity stim.
ask part. to assign a number proportional to intensity

Question 19

response compression

Answer 19

doubling results in less perceived stimuli

Question 20

response expansion

Answer 20

doubling results in more perceived stimuli

Question 21

stevens’ power law

Answer 21

relationship between stimulus magnitude and resulting sensation magnitude

Question 22

psychophysical function

Answer 22

magnitude of physical stimulus vs magnitude of sensory response evoked