Resolution and Acuity Flashcards Preview

psychopysics > Resolution and Acuity > Flashcards

Flashcards in Resolution and Acuity Deck (28):
1

Define Spatial Acuity ?

The smallest spatial detail can be detected, resolved or identified

2

What types of Spatial acuity are there?

Detection acuity
Hyperacuity
Resolution acuity
Identification Acuity

3

What is detection acuity ?

Angular size of the smallest spot or width of line that can just be detected
is it there or is it not (2AFC)

4

What are small objects detection depend on?

Illuminance of the retinal image and not size
increment threshold delta L/L

5

What is retinal image size limited for small objects?

differaction and abberation

6

What is increment threshold?

The ability to detect if one stimulus intensity differs from another

7

What is increment threshold dependent on?

Stimulus size, duration wavelength, and retinal location

8

What is detection acuity of spot?

0.25-0.33' arc

9

What is detection acuity of a line ?

0.0083-0.017' arc

10

What happens to retinal luminance as object gets smaller ?

Retinal luminance decreases

11

How can you detect really small spots/lines?

If they are sufficientyly intense

12

Define hyperacuity?

Smallest spatial offset or difference in location that can be resolved

13

Give examples of hyperacuity?

Displacement
vernier
tilt
stereoacuity

14

What is displacement hyperacuity?

Relative location or displacement of dots or lines

15

What is vernier acuity?

Smallest spatial offset or difference in location that can be resolved

16

What is tilt?

Smallest spatial difference in location that can be resolved

17

What is stereoacuity ?

Smallest spatial difference in location that can be resolved

18

What are results of Hyperacuity?

Under opimum condition with high contrast stimuli 2-6' arc

19

When is hyperacuity suggested to be used?

Media opacities to test neural function- cataract

20

What is resolution acuity?

Smallest separation of two points or lines that can be discriminated

21

What condition does resolution acuity need to be in?

Under optimum conditions 0,5' arc

22

How is it hard to do resolution acuity>?

> need lines of different size, and thickness otehrwise px will know
high luminance causes smaller pupil size more deffraction
astigmatism repeat test on all orientation with lines

23

What does high luminance cause?

Smaller pupil size
diffraction
reduced resolution

24

How does grating resolve problems?

Highest spatial frequency gratings (thin) that subject can detect

25

What is gratings not good for?

Testing resolution acuity

26

What is the advantages of identification acuity?

Highly familiar and easily identified targets
quick and reliable
sensitive to ametropia
less effected by guessing

27

What is high contrast?

Allows for variation in the stimulus or lighting without affecting results significantly

28

What confidence intervals do test have?

95% and VA wil fall within +/- 1 line