Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

EPHE 456 > Human Factors- Vision > Flashcards

Human Factors- Vision Flashcards

1
Q

amplitude of wave =

wavelength of wave =

A
  • perceived as brightness

- perceived as hue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

light is ____________ _______ that is visible to our eyes

A

electromagnetic radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

smaller wave length =

  • order of colour from small wavelength to large
  • what wavelength colour do we perceive the strongest
  • wavelength colour impacts meletonin
A

the higher the energy of the wave and the further it will travel

  • blue- green-yellow-red
  • green
  • blue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

______ is the change in direction of propagation of a wave due to a change in its transmission medium

A

refraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

A lens that can focus parallel light rays to a point 1 meter from its axis has a refractive power of
- what is the refractive power of our eyes when viewing distant objects (48 from the cornea)

A

1 diopter

- 59 diopters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what changes our focal distance?

- the higher the diopter the _____ the refraction

A

the lens

- greater

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

when light enters the eye it is refracted through the ____ and the ____ and focused on the ____

A
  • cornea, lens, retina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how do we adjust the amount of light entering the eye

A

the pupil dilates and constricts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

o focus for near objects we need to increase the refractive power of the lens- this is called?

A

accommodation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how do we accommodate?

  • what does this cause?
  • when relaxed, the _______ ______ pull the lens back into a thinner flatter shape
A

Contraction of the Ciliary Muscle enables the lens to become rounder and have more refractive power

  • fatigue causing
  • suspensory ligament
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how many diopters of accommodation do we have?

- what happens with age? (what is it called)

A

15 diopters of accommodation

- decreases with age - presbyopia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

is accommodation an instantaneous experience?

A

no, you can experience temporarily with a sudden change in gaze

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

light focused in front of the retina is called? this is corrected with?
light focused behind the retina is called? this is corrected with?

A
  • myopia, concave lens

- hypermetropia, convex lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

if you have astigmitism you rely on ______ process to _____

A

cognitive processes to accomodate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what gets strained when squinting to see something, dim lighting, fatigue etc

A

ciliary muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Refractive error due to an unequal curvature of the refractive surface (either cornea and/ or lens)

A

astigmatism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Outer regions of the lens focus light at a point slightly ahead of the mid portion of the lens. This causes vision to be blurred

A

spherical aberration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

a typical eye has ____ microns of spherical aberration

- spherical aberration is reduced to ____ microns –> see it more clear

A

+0.15

+ 0.04

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Objects that are very close require muscular contraction to enable the eyes to ____ (and focus via accommodation) on the object

A

converge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Excessive convergence at a work station causes ?

A

fatigue and muscle imbalances to occur, making the task more difficult and causing strain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

downward gaze requires ____ vergence than an upward gaze

A

less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

3 things to do when working with near object:

A
  • minimize required vergence (closer then put it lower)
  • minimize the required accommodation (have to accommodate more when we gaze down)
  • avoid accommodation traps
    (objects right at the point of accommodation will cause them to constantly adjust in and out of focus)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

sharpness of vision, measured by ability to discern letters or numbers at given distance according to fixed standard, discriminate fine detail

A

visual acuity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

visual acuity is dependent on ?

A

accommodation

25
Q

checkerboard, letter target, landhold ring, parallel bars are example of what type of test

A

acuity measures

26
Q

what does a vision of 20/40 mean?

A

that a person can detect a critical detail at 20 feet that a person with normal vision could detect at 40 feet

27
Q

region of light sensitive receptors

A

the retina

28
Q

2 types of receptors and what they are sensitive to and how man are there

A

rods: light sensitive and responsible for night vision (120 mill)
cones: color sensitive cells densely located in the fovea provide photopic vision (6 mill)

29
Q

central pit composed of closely packed cones in the eye in the centre of the macula responsible for sharp central vision. Necessary for visual detail reading and driving

A

the fovea central

30
Q

___ types of cone types with different sensitivity to _______, any giving colour is perceive by the ________ of firings, Colour blindness is if ___ set of cells is missing

A

3, wavelengths
distributions
one

31
Q
  • what percent of people have normal vision

- what percent of people have deuteranomaly

A
  • 92%

- 2.7%

32
Q
  • Protanopia (< 1% of males) see in shades of?
  • Deuteranopia (<1% of males) see in shades of?
  • tritanomaly/tritanopia (very rare); _____-_______ deficiency blindness
  • monochromacy (extremely rare):
A
  • blue and yellow
  • blue and yellow
  • blue/yellow
  • inability to distinguish any colour
33
Q

rods are mostly distributed where?

- this means we cant do what in the periphery

A
  • in the periphery

- cant identify colour well in our periphery and have less acuity

34
Q

across the colour spectrum we are most sensitive to ? and least sensitive to?

A
  • green, blue/green

- pure red and blue

35
Q

we need very little _____ light to detect differences

A

green

36
Q

we can illuminate a room or sign with this color and not worry about bleaching out our ability to see in dark environments

A

red

37
Q

as we switch from cone to rod vision (day to night), shorter wavelengths appear brighter (green objects appear brighter, red objects appear darker

A

purkinje shift

38
Q

at night we see primarily with the ____ in our eyes and they are indeed more sensitive to all kinds of light than are the _____ which we use primarily for daylight

A

rods, cones

39
Q

our most sensitive light ranges are ______-_____ light during the day and _____ at night

A
  • yellowish green

- green

40
Q

at night sensitive to ___ is near zero

A

red

41
Q

____ ____ ____Contain melanopsin which is Sensitive to blue light and Can modify our circadian rhythm (releases melatonin)

A

retinal ganglion cells

42
Q

light _____ and ______ of exposure determine the impact of self- luminous tablets on melatonin suppression
–> greatest effect after ___ hours

A

level, duration

–> 2 hours (not after 1)

43
Q
  • total light emitted by a source:
  • light falling onto a surface:
  • light reflected by a surface:
A
  • luminous flux
  • illuminance
  • luminance
44
Q

what are the units for lumination/illuminance?

A

lux

45
Q

a common candle emits light with roughly ___cd luminous intensity

A

1

46
Q

common health effects associated with poor lighting include:

A
  • headache and eyestrain
  • neck, back, and shoulder
  • -> when staining to see items because poor lighting
  • falling, tripping, slipping
  • dropping materials or tools
  • depression
47
Q

the main causes of lighting problems are:

A

Insufficient light •  not enough light for the need •  Glare - too much light for the need •  Improper contrast •  Poor distribution, and •  Flicker

48
Q

how does lighting effect performance?

A
  • performance time decreases with increasing amounts of illumination
  • errors decrease as well
49
Q

what is the difference between direct glare and indirect glare

A
  • light sources in the field (direct)

- light sources (reflect, light sources outside the field)

50
Q

2 types of indirect glare

A
  • specular (smooth surface)

- Diffuse (matte surface - a white wall)

51
Q

what are the effects of glare on the work place?

A
  1. Discomfort: annoyance or pain causing discomfort, no change in performance
  2. disability: reduction in ability to perform task, phototropis- natural tendency to gaze at bright objects, transient adaptation- change in contrast
  3. blinding
52
Q

natural tendency to stare at bright lights

A

phototropism

53
Q

3 ways to reduce display reflection

A
  • indirect lighting system
  • blinds/drapes
  • low wattage direct light on documents
54
Q

in unpolarized light, which is most of the light we see, the fluctuations in the electric field are ?
- when light hits a flat surface such as water or the road, some of it become horizontally polarized, which causes glare

A

random- occur in all directions
- only safe, vertically polarized light passes through specifically treated polarized lens (only vertical wave lengths get through)

55
Q

polarized lenses have been chemically treated with a compound whose molecules naturally align parallel to one another, absorbing light and creating a ?

A

microscopic polarization filter

56
Q

ppl can see lights flashing on and off up to to about ? hz

A

50 hz (50 flashes per second)

57
Q

what are the light flicker health effects

A

flourecent lights, complaints about headaches, eye strain and general eye discomfort

58
Q

When compared to regular fluorescent lights with magnetic ballasts, the use of high frequency electronic ballasts (20,000Hz+) in fluorescent lights resulted in more than a___% drop in complaints of eye strain and headaches

A

50

59
Q

we basically can only identify colors we can _____

- why are russions better at separating out blues ?

A

name

- they have more categories for blue “siniy” “goluboy”

EPHE 456 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions