Lecture 6 and Hoppe

Question 1

what does the perception of color depend on

Answer 1

the wavelength of the light, the wavelength change produces a color perception change

Question 2

how much of the population does color vision deficiency affect

Answer 2

about 4.5%

Question 3

what type is the most common in males

Answer 3

red-green deficiency

Question 4

what percentage of males are affected by color deficiency

Answer 4

8%

Question 5

what percentage of females are affected by color deficiency

Answer 5

0.40%

Question 6

how can a person acquire color vision loss

Answer 6

due to disease of the optic nerve or tract (optic neuritis, glaucoma, tumors)

Question 7

what is Kollners law

Answer 7

lesions of the outer layers of the retina cause a yellow-blue defect and the inner layers will cause a red-green defect

Question 8

what is stereopsis

Answer 8

binocular visual perception of 3D space based on retinal disparity

Question 9

can depth perception occur without binocular vision

Answer 9

yes, the brain can use monocular cues to aid in depth perception

Question 10

what is apparent size

Answer 10

small retinal images are further away

Question 11

what is interposition

Answer 11

nearer images conceal further away images

Question 12

what is clarity

Answer 12

water, vapor, and dust make a distant object indistinct and the color is desaturated

Question 13

what is shading

Answer 13

the shadow is interpreted as falling behind the object

Question 14

what is geometric perspective

Answer 14

physically parallel lines converge to a vanishing point

Question 15

what is relative velocity

Answer 15

the velocity of a distance object appears slower than a target moving at the same velocity that is closer

Question 16

what is motion parallax

Answer 16

when you head moves, near objects appear to move in the opposite direction and far objects move in the same direction

Question 17

what are the 5 static cues

Answer 17

apparent size, interposition, clarity, shading, and geometric perspective

Question 18

what are the 2 kinetic cues

Answer 18

relative velocity and motion parallax

Question 19

what is an example of a secondary prevetion

Answer 19

a screening

Question 20

what is a chronic condition

Answer 20

once you have the condition, it stays

Question 21

what is an acute condition

Answer 21

you get sick but always return to a healthy state

Question 22

what is better to screen for, a chronic condition or an acute one

Answer 22

a chronic condition

Question 23

what is prevelence

Answer 23

proportion of people in a given population that have a particular condition

Question 24

what is incidence

Answer 24

the rate at which new cases arise within a given population

Question 25

what can you use to evaluate a screening

Answer 25

a 2 x 2 table

Question 26

what is a false positive

Answer 26

no condition, but were referred (incorrectly identified)

Question 27

what is a false negative

Answer 27

missed the condition in the screening, not referred

Question 28

what is a true positive

Answer 28

they were correctly identified and referred

Question 29

what is a true negative

Answer 29

they do not have the condition and were not referred

Question 30

what is sensitivity

Answer 30

accuracy of the screening procedure to correctly identify all individuals in a population who have a particular condition

Question 31

what is a true positive rate

Answer 31

(sensitivity) how many actual positives were correctly identified

Question 32

what is the formula for the true positive rate

Answer 32

A/ A + B x 100

Question 33

what are the advantages of sensitivity

Answer 33

few false negatives, used for serious but treatable conditions, used early to rule out disease

Question 34

what is specificity

Answer 34

the accuracy of the screening procedure to correctly identify those who do not have the condition

Question 35

what is the true negative rate

Answer 35

(specificity) how many negatives were correctly identified as not having the condition

Question 36

what is the calculation for the true negative rate

Answer 36

C/ C + D x 100

Question 37

what are the advantages of a specificity test

Answer 37

few false positives, used for condition with serious consequences, used to rule in disease or confirm a suspected diagnosis

Question 38

what happens to specificity as sensitivity rises

Answer 38

it declines

Question 39

what is a positive predictive value

Answer 39

probability that someone who failed the screening really does have the condition

Question 40

what is the calculation for positive predictive value

Answer 40

A/ A + B x 100

Question 41

what is negative predictive value

Answer 41

probability that someone who passed the screening really does not have the condition

Question 42

what is the calculation for the negative predictive value

Answer 42

D/ C+D x 100

Question 43

what is yield

Answer 43

the measure of the previously unrecognized cases that are treated as a result of the screening

Question 44

how is yield related to sensitivity and specificity

Answer 44

if either are low, the yield will be low