Flicker

Question 1

Temporal Frequency

Answer 1

1/Temporal Period

Question 2

TCSF

Answer 2

defines visual sensitivity to time-varying stimuli

Question 3

CFF

Answer 3

highest detectable TF (temporal frequency)

Question 4

Granit-Harper Law

Answer 4

CFF increases with log target area
(CFF is directly proportional to the log of stimulus luminance)

Question 5

Ferry-Porter Law

Answer 5

CFF increases linearly with log luminance over much of the photopic range
(CFF is directly proportional to the log of stimulus area)

Question 6

Peak CS (Photopic TCSF)

Answer 6

100-200 (intermediate TF)

Question 7

Talbot-Plateau Law

Answer 7

received brightness of flickering light depends on TF

Question 8

Brucke-Bartley Brightness Enhancement

Answer 8

perceived brightness increases for intermediate TFs of flicker, below the CFF (peak at 8 Hz)

Question 9

Broca-Sulzer Effect

Answer 9

Enhanced brightness also occurs for single temporal pulses of 50-100 ms

Question 10

For small dim targets, where is CFF the highest?

Answer 10

fovea

Question 11

For large dim targets, where is CFF the highest?

Answer 11

peripherally

Question 12

How does the shape of the TCSF function change with decreasing luminance?

Answer 12

1. Peak moves to lower TF
2. Maximum CS declines
3. Photopic function band pass
4. Scotopic function low pass
5. CFF decreases

Question 13

Visual Masking

Answer 13

temporal summation of target with spatially overlapping masking stimulus effectively reduces target contrast

Question 14

Backward Masking

Answer 14

target -> masker (masker comes after) (+)

Question 15

Forward Masking

Answer 15

masker -> target (masker comes before) (-)

Question 16

Metacontrast

Answer 16

form of backwards masking

Question 17

Paracontrast

Answer 17

form of forward masking

Question 18

What accounts for the shape of the TCSF?

Answer 18

1. Delayed inhibition (low drop at low TF)
2. Delayed inhitbton increases modulation (intermediate peak @ 8 Hz)
3. Persistance (temporal summation) (CFF cut-off)

Question 19

Temporal Summation/Persistance

Answer 19

When flicker cycle is shorter than persistence, neural signals add, no resulting modulation ( CFF cut-off)

Question 20

Delayed Inhibition

Answer 20

Low Temporal Frequency = destructive interference